summaryrefslogtreecommitdiffstats
path: root/cpukit/libblock/src/flashdisk.c
blob: b778ab5a19bb0966d7702b5f7afb2e81878dbdc8 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
2369
2370
2371
2372
2373
2374
2375
2376
2377
2378
2379
2380
2381
2382
2383
2384
2385
2386
2387
2388
2389
2390
2391
2392
2393
2394
2395
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417
2418
2419
2420
2421
2422
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
2451
2452
2453
2454
2455
2456
2457
2458
2459
2460
2461
2462
2463
2464
2465
2466
2467
2468
2469
2470
2471
2472
2473
2474
2475
2476
2477
2478
2479
2480
2481
2482
2483
2484
2485
2486
2487
2488
2489
2490
2491
2492
2493
2494
2495
2496
2497
2498
2499
2500
2501
2502
2503
2504
2505
2506
2507
2508
2509
2510
2511
2512
2513
2514
2515
2516
2517
2518
2519
2520
2521
2522
2523
2524
2525
2526
2527
2528
2529
2530
2531
2532
2533
2534
2535
2536
2537
2538
2539
2540
2541
2542
2543
2544
2545
2546
2547
2548
2549
2550
2551
2552
2553
2554
2555
2556
2557
2558
2559
2560
2561
2562
2563
2564
2565
2566
2567
2568
2569
2570
2571
2572
2573
2574
2575
2576
2577
2578
2579
2580
2581
2582
2583
2584
2585
2586
2587
2588
2589
2590
2591
2592
2593
2594
2595
2596
2597
2598
2599
2600
2601
2602
2603
2604
2605
2606
2607
2608
2609
2610
2611
2612
2613
2614
2615
2616
2617
/*
 * flashdisk.c -- Flash disk block device implementation
 *
 * Copyright (C) 2007 Chris Johns
 *
 * The license and distribution terms for this file may be
 * found in the file LICENSE in this distribution or at
 * http://www.rtems.com/license/LICENSE.
 *
 * $Id$
 */

/*
 * The use of pages can vary. The rtems_fdisk_seg_*_page set
 * routines use an absolute page number relative to the segment
 * while all other page numbers are relative to the number of
 * page descriptor pages a segment has. You need to add the
 * number of page descriptor pages (pages_desc) to the page number
 * when call the rtems_fdisk_seg_*_page functions.
 *
 * You must always show the page number as relative in any trace
 * or error message as device-segment-page and if you have to
 * the page number as absolute use device-segment~page. This
 * can be seen in the page copy routine.
 *
 * The code is like this to avoid needing the pass the pages_desc
 * value around. It is only used in selected places and so the
 * extra parameter was avoided.
 */

#if HAVE_CONFIG_H
#include "config.h"
#endif

#include <rtems.h>
#include <rtems/libio.h>
#include <errno.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <inttypes.h>

#include "rtems/blkdev.h"
#include "rtems/diskdevs.h"
#include "rtems/flashdisk.h"

/**
 * Control tracing. It can be compiled out of the code for small
 * footprint targets. Leave in by default.
 */
#if !defined (RTEMS_FDISK_TRACE)
#define RTEMS_FDISK_TRACE 1
#endif

/**
 * The start of a segment has a segment control table. This hold the CRC and
 * block number for the page.
 *
 * @todo A sequence number for the block could be added. This would
 *       mean a larger descriptor size. Need to make the sequence
 *       large like 20+ bits so a large file system would not have
 *       more blocks available than the sequence number.
 */
typedef struct rtems_fdisk_page_desc
{
  uint16_t crc;       /**< The page's checksum. */
  uint16_t flags;     /**< The flags for the page. */
  uint32_t block;     /**< The block number. */
} rtems_fdisk_page_desc;

/**
 * Flag the page as active.
 */
#define RTEMS_FDISK_PAGE_ACTIVE (1 << 0)

/**
 * Flag the page as used.
 */
#define RTEMS_FDISK_PAGE_USED (1 << 1)

/**
 * Flash Segment Control holds the pointer to the segment, number of
 * pages, various page stats and the memory copy of the page descriptors.
 */
typedef struct rtems_fdisk_segment_ctl
{
  /**
   * Segments with available pages are maintained as a linked list.
   */
  struct rtems_fdisk_segment_ctl* next;

  /**
   * The descriptor provided by the low-level driver.
   */
  const rtems_fdisk_segment_desc* descriptor;

  /**
   * The device this segment resides on.
   */
  uint32_t device;

  /**
   * The segment in the device. This must be within the
   * segment descriptor.
   */
  uint32_t segment;

  /**
   * The in-memory ocpy of the page descriptors found at
   * the start of the segment in the flash device.
   */
  rtems_fdisk_page_desc* page_descriptors;

  /*
   * Page stats.
   *
   * A bad page does not checksum or is not erased or has invalid flags.
   */
  uint32_t pages;         /**< Total number of pages in the segment. */
  uint32_t pages_desc;    /**< Number of pages used for page descriptors. */
  uint32_t pages_active;  /**< Number of pages flagged as active. */
  uint32_t pages_used;    /**< Number of pages flagged as used. */
  uint32_t pages_bad;     /**< Number of pages detected as bad. */

  uint32_t failed;        /**< The segment has failed. */

  uint32_t erased;        /**< Counter to debugging. Wear support would
                               remove this. */
} rtems_fdisk_segment_ctl;

/**
 * Segment control table queue.
 */
typedef struct rtems_fdisk_segment_ctl_queue
{
  rtems_fdisk_segment_ctl* head;
  rtems_fdisk_segment_ctl* tail;
  uint32_t                 count;
} rtems_fdisk_segment_ctl_queue;

/**
 * Flash Device Control holds the segment controls
 */
typedef struct rtems_fdisk_device_ctl
{
  rtems_fdisk_segment_ctl*       segments;      /**< Segment controls. */
  uint32_t                       segment_count; /**< Segment control count. */
  const rtems_fdisk_device_desc* descriptor;    /**< Device descriptor. */
} rtems_fdisk_device_ctl;

/**
 * The Block control holds the segment and page with the data.
 */
typedef struct rtems_fdisk_block_ctl
{
  rtems_fdisk_segment_ctl* segment; /**< The segment with the block. */
  uint32_t                 page;    /**< The page in the segment. */
} rtems_fdisk_block_ctl;

/**
 * The virtual block table holds the mapping for blocks as seen by the disk
 * drivers to the device, segment and page numbers of the physical device.
 */
typedef struct rtems_flashdisk
{
  rtems_device_major_number major;         /**< The driver's major number. */
  rtems_device_minor_number minor;         /**< The driver's minor number. */

  uint32_t flags;                          /**< configuration flags. */

  uint32_t compact_segs;                   /**< Max segs to compact at once. */
  uint32_t avail_compact_segs;             /**< The number of segments when
                                                compaction occurs when writing. */

  uint32_t               block_size;       /**< The block size for this disk. */
  rtems_fdisk_block_ctl* blocks;           /**< The block to segment-page
                                                mappings. */
  uint32_t block_count;                    /**< The number of avail. blocks. */
  uint32_t unavail_blocks;                 /**< The number of unavail blocks. */
  uint32_t starvation_threshold;           /**< Erased blocks starvation threshold. */
  uint32_t erased_blocks;                  /**< The number of erased blocks. */

  rtems_fdisk_device_ctl* devices;         /**< The flash devices for this
                                                disk. */
  uint32_t                device_count;    /**< The number of flash devices. */

  rtems_fdisk_segment_ctl_queue available; /**< The queue of segments with
                                                available pages. */
  rtems_fdisk_segment_ctl_queue used;      /**< The list of segments with all
                                                pages used. */
  rtems_fdisk_segment_ctl_queue erase;     /**< The list of segments to be
                                                erased. */
  rtems_fdisk_segment_ctl_queue failed;    /**< The list of segments that failed
                                                when being erased. */
  rtems_id lock;                           /**< Mutex for threading protection.*/

  uint8_t* copy_buffer;                    /**< Copy buf used during compacting */

  uint32_t info_level;                     /**< The info trace level. */

  uint32_t starvations;                    /**< Erased blocks starvations counter. */
} rtems_flashdisk;

/**
 * The array of flash disks we support.
 */
static rtems_flashdisk* rtems_flashdisks;

/**
 * The number of flash disks we have.
 */
static uint32_t rtems_flashdisk_count;

/**
 * The CRC16 factor table. Created during initialisation.
 */
static uint16_t* rtems_fdisk_crc16_factor;

/**
 * Calculate the CRC16 checksum.
 *
 * @param _b The byte to checksum.
 * @param _c The current checksum.
 */
#define rtems_fdisk_calc_crc16(_b, _c) \
  rtems_fdisk_crc16_factor[((_b) ^ ((_c) & 0xff)) & 0xff] ^ (((_c) >> 8) & 0xff)

/**
 * Generate the CRC table.
 *
 * @param pattern The seed pattern for the table of factors.
 * @relval RTEMS_SUCCESSFUL The table was generated.
 * @retval RTEMS_NO_MEMORY The table could not be allocated from the heap.
 */
static rtems_status_code
rtems_fdisk_crc16_gen_factors (uint16_t pattern)
{
  uint32_t b;

  rtems_fdisk_crc16_factor = malloc (sizeof (uint16_t) * 256);
  if (!rtems_fdisk_crc16_factor)
    return RTEMS_NO_MEMORY;

  for (b = 0; b < 256; b++)
  {
    uint32_t i;
    uint16_t v = b;
    for (i = 8; i--;)
      v = v & 1 ? (v >> 1) ^ pattern : v >> 1;
    rtems_fdisk_crc16_factor[b] = v & 0xffff;
  }
  return RTEMS_SUCCESSFUL;
}

#if RTEMS_FDISK_TRACE
/**
 * Print a message to the flash disk output and flush it.
 *
 * @param fd The flashdisk control structure.
 * @param format The format string. See printf for details.
 * @param ... The arguments for the format text.
 * @return int The number of bytes written to the output.
 */
static int
rtems_fdisk_printf (const rtems_flashdisk* fd, const char *format, ...)
{
  int ret = 0;
  if (fd->info_level >= 3)
  {
    va_list args;
    va_start (args, format);
    fprintf (stdout, "fdisk:");
    ret =  vfprintf (stdout, format, args);
    fprintf (stdout, "\n");
    fflush (stdout);
    va_end (args);
  }
  return ret;
}

static bool
rtems_fdisk_is_erased_blocks_starvation (rtems_flashdisk* fd)
{
  bool starvation = fd->erased_blocks < fd->starvation_threshold;

  if (starvation)
    fd->starvations++;

  return starvation;
}

/**
 * Print a info message to the flash disk output and flush it.
 *
 * @param fd The flashdisk control structure.
 * @param format The format string. See printf for details.
 * @param ... The arguments for the format text.
 * @return int The number of bytes written to the output.
 */
static int
rtems_fdisk_info (const rtems_flashdisk* fd, const char *format, ...)
{
  int ret = 0;
  if (fd->info_level >= 2)
  {
    va_list args;
    va_start (args, format);
    fprintf (stdout, "fdisk:");
    ret =  vfprintf (stdout, format, args);
    fprintf (stdout, "\n");
    fflush (stdout);
    va_end (args);
  }
  return ret;
}

/**
 * Print a warning to the flash disk output and flush it.
 *
 * @param fd The flashdisk control structure.
 * @param format The format string. See printf for details.
 * @param ... The arguments for the format text.
 * @return int The number of bytes written to the output.
 */
static int
rtems_fdisk_warning (const rtems_flashdisk* fd, const char *format, ...)
{
  int ret = 0;
  if (fd->info_level >= 1)
  {
    va_list args;
    va_start (args, format);
    fprintf (stdout, "fdisk:warning:");
    ret =  vfprintf (stdout, format, args);
    fprintf (stdout, "\n");
    fflush (stdout);
    va_end (args);
  }
  return ret;
}
#endif

/**
 * Print an error to the flash disk output and flush it.
 *
 * @param format The format string. See printf for details.
 * @param ... The arguments for the format text.
 * @return int The number of bytes written to the output.
 */
static int
rtems_fdisk_error (const char *format, ...)
{
  int ret;
  va_list args;
  va_start (args, format);
  fprintf (stderr, "fdisk:error:");
  ret =  vfprintf (stderr, format, args);
  fprintf (stderr, "\n");
  fflush (stderr);
  va_end (args);
  return ret;
}

/**
 * Print an abort message, flush it then abort the program.
 *
 * @param format The format string. See printf for details.
 * @param ... The arguments for the format text.
 */
static void
rtems_fdisk_abort (const char *format, ...)
{
  va_list args;
  va_start (args, format);
  fprintf (stderr, "fdisk:abort:");
  vfprintf (stderr, format, args);
  fprintf (stderr, "\n");
  fflush (stderr);
  va_end (args);
  exit (1);
}

/**
 * Initialise the segment control queue.
 */
static void
rtems_fdisk_segment_queue_init (rtems_fdisk_segment_ctl_queue* queue)
{
  queue->head = queue->tail = 0;
  queue->count = 0;
}

/**
 * Push to the head of the segment control queue.
 */
static void
rtems_fdisk_segment_queue_push_head (rtems_fdisk_segment_ctl_queue* queue,
                                     rtems_fdisk_segment_ctl*       sc)
{
  if (sc)
  {
    sc->next = queue->head;
    queue->head = sc;

    if (queue->tail == 0)
      queue->tail = sc;
    queue->count++;
  }
}

/**
 * Pop the head of the segment control queue.
 */
static rtems_fdisk_segment_ctl*
rtems_fdisk_segment_queue_pop_head (rtems_fdisk_segment_ctl_queue* queue)
{
  if (queue->head)
  {
    rtems_fdisk_segment_ctl* sc = queue->head;

    queue->head = sc->next;
    if (!queue->head)
      queue->tail = 0;

    queue->count--;

    sc->next = 0;

    return sc;
  }

  return 0;
}

/**
 * Push to the tail of the segment control queue.
 */
static void
rtems_fdisk_segment_queue_push_tail (rtems_fdisk_segment_ctl_queue* queue,
                                     rtems_fdisk_segment_ctl*       sc)
{
  if (sc)
  {
    sc->next = 0;

    if (queue->head)
    {
      queue->tail->next = sc;
      queue->tail       = sc;
    }
    else
    {
      queue->head = queue->tail = sc;
    }

    queue->count++;
  }
}

/**
 * Remove from the segment control queue.
 */
static void
rtems_fdisk_segment_queue_remove (rtems_fdisk_segment_ctl_queue* queue,
                                  rtems_fdisk_segment_ctl*       sc)
{
  rtems_fdisk_segment_ctl* prev = 0;
  rtems_fdisk_segment_ctl* it = queue->head;

  /*
   * Do not change sc->next as sc could be on another queue.
   */

  while (it)
  {
    if (sc == it)
    {
      if (prev == 0)
      {
        queue->head = sc->next;
        if (queue->head == 0)
          queue->tail = 0;
      }
      else
      {
        prev->next = sc->next;
        if (queue->tail == sc)
          queue->tail = prev;
      }
      sc->next = 0;
      queue->count--;
      break;
    }

    prev = it;
    it = it->next;
  }
}

/**
 * Insert into the segment control queue before the specific
 * segment control item.
 */
static void
rtems_fdisk_segment_queue_insert_before (rtems_fdisk_segment_ctl_queue* queue,
                                         rtems_fdisk_segment_ctl*       item,
                                         rtems_fdisk_segment_ctl*       sc)
{
  if (item)
  {
    rtems_fdisk_segment_ctl** prev = &queue->head;
    rtems_fdisk_segment_ctl*  it = queue->head;

    while (it)
    {
      if (item == it)
      {
        sc->next = item;
        *prev = sc;
        queue->count++;
        return;
      }

      prev = &it->next;
      it = it->next;
    }
  }

  rtems_fdisk_segment_queue_push_tail (queue, sc);
}

/**
 * Count the number of elements on the list.
 */
static uint32_t
rtems_fdisk_segment_queue_count (rtems_fdisk_segment_ctl_queue* queue)
{
  return queue->count;
}

/**
 * Count the number of elements on the list.
 */
static uint32_t
rtems_fdisk_segment_count_queue (rtems_fdisk_segment_ctl_queue* queue)
{
  rtems_fdisk_segment_ctl* sc = queue->head;
  uint32_t                 count = 0;

  while (sc)
  {
    count++;
    sc = sc->next;
  }

  return count;
}

/**
 * See if a segment control is present on this queue.
 */
static bool
rtems_fdisk_segment_queue_present (rtems_fdisk_segment_ctl_queue* queue,
                                   rtems_fdisk_segment_ctl*       sc)
{
  rtems_fdisk_segment_ctl*  it = queue->head;

  while (it)
  {
    if (it == sc)
      return true;
    it = it->next;
  }

  return false;
}

/**
 * Format a string with the queue status.
 */
static void
rtems_fdisk_queue_status (rtems_flashdisk*         fd,
                          rtems_fdisk_segment_ctl* sc,
                          char                     queues[5])
{
  queues[0] = rtems_fdisk_segment_queue_present (&fd->available, sc) ? 'A' : '-';
  queues[1] = rtems_fdisk_segment_queue_present (&fd->used, sc)      ? 'U' : '-';
  queues[2] = rtems_fdisk_segment_queue_present (&fd->erase, sc)     ? 'E' : '-';
  queues[3] = rtems_fdisk_segment_queue_present (&fd->failed, sc)    ? 'F' : '-';
  queues[4] = '\0';
}

/**
 * Check if the page descriptor is erased.
 */
static bool
rtems_fdisk_page_desc_erased (const rtems_fdisk_page_desc* pd)
{
  return ((pd->crc == 0xffff) &&
          (pd->flags == 0xffff) &&
          (pd->block == 0xffffffff)) ? true : false;
}

/**
 * Check if the flags are set. The flags are inverted as we can
 * only set a flag by changing it from 1 to 0.
 */
static bool
rtems_fdisk_page_desc_flags_set (rtems_fdisk_page_desc* pd, uint16_t flags)
{
  return (pd->flags & flags) == 0 ? true : false;
}

/**
 * Check if the flags are clear. The flags are inverted as we can
 * only set a flag by changing it from 1 to 0.
 */
static bool
rtems_fdisk_page_desc_flags_clear (rtems_fdisk_page_desc* pd, uint16_t flags)
{
  return (pd->flags & flags) == flags ? true : false;
}

/**
 * Set the flags. Setting means clear the bit to 0.
 */
static void
rtems_fdisk_page_desc_set_flags (rtems_fdisk_page_desc* pd, uint16_t flags)
{
  pd->flags &= ~flags;
}

/**
 * Get the segment descriptor for a device and segment. There are
 * no range checks.
 */
static const rtems_fdisk_segment_desc*
rtems_fdisk_seg_descriptor (const rtems_flashdisk* fd,
                            uint32_t               device,
                            uint32_t               segment)
{
  return fd->devices[device].segments[segment].descriptor;
}

/**
 * Count the segments for a device.
 */
static uint32_t
rtems_fdisk_count_segments (const rtems_fdisk_device_desc* dd)
{
  uint32_t count = 0;
  uint32_t segment;
  for (segment = 0; segment < dd->segment_count; segment++)
    count += dd->segments[segment].count;
  return count;
}

/**
 * Calculate the pages in a segment give the segment size and the
 * page size.
 *
 * @param sd The segment descriptor.
 * @param page_size The page size in bytes.
 */
static uint32_t
rtems_fdisk_pages_in_segment (const rtems_fdisk_segment_desc* sd,
                              uint32_t                        page_size)
{
  return sd->size / page_size;
}

/**
 * Calculate the number of pages needed to hold the page descriptors.
 * The calculation need to round up.
 *
 * The segment control contains the number of pages used as descriptors
 * and should be used rather than this call where possible.
 */
static uint32_t
rtems_fdisk_page_desc_pages (const rtems_fdisk_segment_desc* sd,
                             uint32_t                        page_size)
{
  uint32_t pages = rtems_fdisk_pages_in_segment (sd, page_size);
  uint32_t bytes = pages * sizeof (rtems_fdisk_page_desc);
  return ((bytes - 1) / page_size) + 1;
}

/**
 * The number of available pages is the total pages less the
 * active, used and bad pages.
 */
static uint32_t
rtems_fdisk_seg_pages_available (const rtems_fdisk_segment_ctl* sc)
{
  return sc->pages - (sc->pages_active + sc->pages_used + sc->pages_bad);
}
/**
 * Find the next available page in a segment.
 */
static uint32_t
rtems_fdisk_seg_next_available_page (rtems_fdisk_segment_ctl* sc)
{
  rtems_fdisk_page_desc* pd = &sc->page_descriptors[0];
  uint32_t               page;

  for (page = 0; page < sc->pages; page++, pd++)
    if (rtems_fdisk_page_desc_erased (pd))
      break;

  return page;
}

/**
 * Find the segment on the queue that has the most free pages.
 */
static rtems_fdisk_segment_ctl*
rtems_fdisk_seg_most_available (const rtems_fdisk_segment_ctl_queue* queue)
{
  rtems_fdisk_segment_ctl* sc      = queue->head;
  rtems_fdisk_segment_ctl* biggest = queue->head;

  while (sc)
  {
    if (rtems_fdisk_seg_pages_available (sc) >
        rtems_fdisk_seg_pages_available (biggest))
      biggest = sc;
    sc = sc->next;
  }

  return biggest;
}

/**
 * Is the segment all used ?
 */
#if 0
static bool
rtems_fdisk_seg_pages_all_used (const rtems_fdisk_segment_ctl* sc)
{
  return sc->pages == (sc->pages_used + sc->pages_bad) ? true : false;
}
#endif

/**
 * Calculate the blocks in a device. This is the number of
 * pages less the pages hold page descriptors. This call be used
 * early in the initialisation process and does not rely on
 * the system being fully initialised.
 *
 * @param dd The device descriptor.
 * @param page_size The page size in bytes.
 */
static uint32_t
rtems_fdisk_blocks_in_device (const rtems_fdisk_device_desc* dd,
                              uint32_t                       page_size)
{
  uint32_t count = 0;
  uint32_t s;
  for (s = 0; s < dd->segment_count; s++)
  {
    const rtems_fdisk_segment_desc* sd = &dd->segments[s];
    count +=
      (rtems_fdisk_pages_in_segment (sd, page_size) -
       rtems_fdisk_page_desc_pages (sd, page_size)) * sd->count;
  }
  return count;
}

/**
 * Read a block of data from a segment.
 */
static int
rtems_fdisk_seg_read (const rtems_flashdisk*         fd,
                      const rtems_fdisk_segment_ctl* sc,
                      uint32_t                       offset,
                      void*                          buffer,
                      uint32_t                       size)
{
  uint32_t                           device;
  uint32_t                           segment;
  const rtems_fdisk_segment_desc*    sd;
  const rtems_fdisk_driver_handlers* ops;
  device = sc->device;
  segment = sc->segment;
  sd = rtems_fdisk_seg_descriptor (fd, device, segment);
  ops = fd->devices[device].descriptor->flash_ops;
#if RTEMS_FDISK_TRACE
  rtems_fdisk_printf (fd, "  seg-read: %02d-%03d: o=%08x s=%d",
                      device, segment, offset, size);
#endif
  return ops->read (sd, device, segment, offset, buffer, size);
}

/**
 * Write a block of data to a segment. It is assumed the
 * location in the segment is erased and able to take the
 * data.
 */
static int
rtems_fdisk_seg_write (const rtems_flashdisk*   fd,
                       rtems_fdisk_segment_ctl* sc,
                       uint32_t                 offset,
                       const void*              buffer,
                       uint32_t                 size)
{
  int ret;
  uint32_t                           device;
  uint32_t                           segment;
  const rtems_fdisk_segment_desc*    sd;
  const rtems_fdisk_driver_handlers* ops;
  device = sc->device;
  segment = sc->segment;
  sd = rtems_fdisk_seg_descriptor (fd, device, segment);
  ops = fd->devices[device].descriptor->flash_ops;
#if RTEMS_FDISK_TRACE
  rtems_fdisk_printf (fd, "  seg-write: %02d-%03d: o=%08x s=%d",
                      device, segment, offset, size);
#endif
  ret = ops->write (sd, device, segment, offset, buffer, size);
  if (ret)
    sc->failed = true;

  return ret;
}

/**
 * Blank check the area of a segment.
 */
static int
rtems_fdisk_seg_blank_check (const rtems_flashdisk*   fd,
                             rtems_fdisk_segment_ctl* sc,
                             uint32_t                 offset,
                             uint32_t                 size)
{
  uint32_t                           device;
  uint32_t                           segment;
  const rtems_fdisk_segment_desc*    sd;
  const rtems_fdisk_driver_handlers* ops;
  device = sc->device;
  segment = sc->segment;
  sd = rtems_fdisk_seg_descriptor (fd, device, segment);
  ops = fd->devices[device].descriptor->flash_ops;
#if RTEMS_FDISK_TRACE
  rtems_fdisk_printf (fd, "  seg-blank: %02d-%03d: o=%08x s=%d",
                      device, segment, offset, size);
#endif
  return ops->blank (sd, device, segment, offset, size);
}
/**
 * Verify the data with the data in a segment.
 */
static int
rtems_fdisk_seg_verify (const rtems_flashdisk* fd,
                        uint32_t               device,
                        uint32_t               segment,
                        uint32_t               offset,
                        const void*            buffer,
                        uint32_t               size)
{
  const rtems_fdisk_segment_desc*    sd;
  const rtems_fdisk_driver_handlers* ops;
  sd  = rtems_fdisk_seg_descriptor (fd, device, segment);
  ops = fd->devices[device].descriptor->flash_ops;
#if RTEMS_FDISK_TRACE
  rtems_fdisk_printf (fd, "  seg-verify: %02d-%03d: o=%08x s=%d",
                      device, segment, offset, size);
#endif
  return ops->verify (sd, device, segment, offset, buffer, size);
}

/**
 * Blank check a page of data in a segment.
 */
static int
rtems_fdisk_seg_blank_check_page (const rtems_flashdisk*   fd,
                                  rtems_fdisk_segment_ctl* sc,
                                  uint32_t                 page)
{
  return rtems_fdisk_seg_blank_check (fd, sc,
                                      page * fd->block_size, fd->block_size);
}

/**
 * Read a page of data from a segment.
 */
static int
rtems_fdisk_seg_read_page (const rtems_flashdisk*   fd,
                           rtems_fdisk_segment_ctl* sc,
                           uint32_t                 page,
                           void*                    buffer)
{
  return rtems_fdisk_seg_read (fd, sc,
                               page * fd->block_size, buffer, fd->block_size);
}

/**
 * Write a page of data to a segment.
 */
static int
rtems_fdisk_seg_write_page (rtems_flashdisk*         fd,
                            rtems_fdisk_segment_ctl* sc,
                            uint32_t                 page,
                            const void*              buffer)
{
  if ((fd->flags & RTEMS_FDISK_BLANK_CHECK_BEFORE_WRITE))
  {
    int ret = rtems_fdisk_seg_blank_check_page (fd, sc, page);
    if (ret)
      return ret;
  }
  --fd->erased_blocks;
  return rtems_fdisk_seg_write (fd, sc,
                                page * fd->block_size, buffer, fd->block_size);
}

/**
 * Verify a page of data with the data in the segment.
 */
static int
rtems_fdisk_seg_verify_page (const rtems_flashdisk* fd,
                             uint32_t               device,
                             uint32_t               segment,
                             uint32_t               page,
                             const void*            buffer)
{
  return rtems_fdisk_seg_verify (fd, device, segment,
                                 page * fd->block_size, buffer, fd->block_size);
}

/**
 * Copy a page of data from one segment to another segment.
 */
static int
rtems_fdisk_seg_copy_page (rtems_flashdisk*         fd,
                           rtems_fdisk_segment_ctl* src_sc,
                           uint32_t                 src_page,
                           rtems_fdisk_segment_ctl* dst_sc,
                           uint32_t                 dst_page)
{
  int ret;
#if RTEMS_FDISK_TRACE
  rtems_fdisk_printf (fd, "  seg-copy-page: %02d-%03d~%03d=>%02d-%03d~%03d",
                      src_sc->device, src_sc->segment, src_page,
                      dst_sc->device, dst_sc->segment, dst_page);
#endif
  ret = rtems_fdisk_seg_read_page (fd, src_sc, src_page,
                                   fd->copy_buffer);
  if (ret)
    return ret;
  return rtems_fdisk_seg_write_page (fd, dst_sc, dst_page,
                                     fd->copy_buffer);
}

/**
 * Write the page descriptor to a segment. This code assumes the page
 * descriptors are located at offset 0 in the segment.
 */
static int
rtems_fdisk_seg_write_page_desc (const rtems_flashdisk*       fd,
                                 rtems_fdisk_segment_ctl*     sc,
                                 uint32_t                     page,
                                 const rtems_fdisk_page_desc* page_desc)
{
  uint32_t offset = page * sizeof (rtems_fdisk_page_desc);
  if ((fd->flags & RTEMS_FDISK_BLANK_CHECK_BEFORE_WRITE))
  {
    int ret = rtems_fdisk_seg_blank_check (fd, sc,
                                           offset,
                                           sizeof (rtems_fdisk_page_desc));
    if (ret)
      return ret;
  }
  return rtems_fdisk_seg_write (fd, sc, offset,
                                page_desc, sizeof (rtems_fdisk_page_desc));
}

/**
 * Write the page descriptor flags to a segment. This code assumes the page
 * descriptors are located at offset 0 in the segment.
 */
static int
rtems_fdisk_seg_write_page_desc_flags (const rtems_flashdisk*       fd,
                                       rtems_fdisk_segment_ctl*     sc,
                                       uint32_t                     page,
                                       const rtems_fdisk_page_desc* page_desc)
{
  uint32_t offset = ((page * sizeof (rtems_fdisk_page_desc)) +
                     ((uint8_t*) &page_desc->flags) - ((uint8_t*) page_desc));
  if ((fd->flags & RTEMS_FDISK_BLANK_CHECK_BEFORE_WRITE))
  {
    uint16_t flash_flags;
    int      ret;
    ret = rtems_fdisk_seg_read (fd, sc, offset,
                                &flash_flags, sizeof (flash_flags));
    if (ret)
      return ret;
    if ((flash_flags & page_desc->flags) != page_desc->flags)
    {
      rtems_fdisk_error ("  seg-write-page-flags: %02d-%03d-%03d: "
                         "flags not erased: 0x%04 -> 0x%04x",
                         sc->device, sc->segment, page,
                         flash_flags, page_desc->flags);
      return ret;
    }
  }
  return rtems_fdisk_seg_write (fd, sc, offset,
                                &page_desc->flags, sizeof (page_desc->flags));
}

/**
 * Erase a device.
 */
static int
rtems_fdisk_device_erase (const rtems_flashdisk* fd, uint32_t device)
{
  const rtems_fdisk_driver_handlers* ops;
  ops = fd->devices[device].descriptor->flash_ops;
#if RTEMS_FDISK_TRACE
  rtems_fdisk_printf (fd, " device-erase: %02d", device);
#endif
  return ops->erase_device (fd->devices[device].descriptor, device);
}

/**
 * Erase all flash.
 */
static int
rtems_fdisk_erase_flash (const rtems_flashdisk* fd)
{
  uint32_t device;
  for (device = 0; device < fd->device_count; device++)
  {
    int ret;

#if RTEMS_FDISK_TRACE
    rtems_fdisk_info (fd, " erase-flash:%02d", device);
#endif

    ret = rtems_fdisk_device_erase (fd, device);

    if (ret != 0)
      return ret;
  }
  return 0;
}

/**
 * Calculate the checksum of a page in a segment.
 */
static uint16_t
rtems_fdisk_page_checksum (const uint8_t* buffer, uint32_t page_size)
{
  uint16_t cs = 0xffff;
  uint32_t i;

  for (i = 0; i < page_size; i++, buffer++)
    cs = rtems_fdisk_calc_crc16 (cs, *buffer);

  return cs;
}

/**
 * Erase the segment.
 */
static int
rtems_fdisk_erase_segment (rtems_flashdisk* fd, rtems_fdisk_segment_ctl* sc)
{
  int                                ret;
  uint32_t                           device;
  uint32_t                           segment;
  const rtems_fdisk_segment_desc*    sd;
  const rtems_fdisk_driver_handlers* ops;
  device = sc->device;
  segment = sc->segment;
  sd = rtems_fdisk_seg_descriptor (fd, device, segment);
  ops = fd->devices[device].descriptor->flash_ops;
  ret = ops->erase (sd, device, segment);
  if (ret)
  {
    rtems_fdisk_error (" erase-segment:%02d-%03d: "      \
                       "segment erase failed: %s (%d)",
                       sc->device, sc->segment, strerror (ret), ret);
    sc->failed = true;
    if (!rtems_fdisk_segment_queue_present (&fd->failed, sc))
      rtems_fdisk_segment_queue_push_tail (&fd->failed, sc);
    return ret;
  }

  fd->erased_blocks += sc->pages;
  sc->erased++;

  memset (sc->page_descriptors, 0xff, sc->pages_desc * fd->block_size);

  sc->pages_active = 0;
  sc->pages_used   = 0;
  sc->pages_bad    = 0;

  sc->failed = false;

  /*
   * Push to the tail of the available queue. It is a very
   * simple type of wear reduction. Every other available
   * segment will now get a go.
   */
  rtems_fdisk_segment_queue_push_tail (&fd->available, sc);

  return 0;
}

/**
 * Erase used segment.
 */
static int
rtems_fdisk_erase_used (rtems_flashdisk* fd)
{
  rtems_fdisk_segment_ctl* sc;
  int                      latched_ret = 0;

  while ((sc = rtems_fdisk_segment_queue_pop_head (&fd->erase)))
  {
    /*
     * The segment will either end up on the available queue or
     * the failed queue.
     */
    int ret = rtems_fdisk_erase_segment (fd, sc);
    if (ret && !latched_ret)
      latched_ret = ret;
  }

  return latched_ret;
}

/**
 * Queue a segment. This is done after some of the stats for the segment
 * have been changed and this may effect the order the segment pages have in
 * the queue of available pages.
 *
 * @param fd The flash disk control table.
 * @param sc The segment control table to be reallocated
 */
static void
rtems_fdisk_queue_segment (rtems_flashdisk* fd, rtems_fdisk_segment_ctl* sc)
{
#if RTEMS_FDISK_TRACE
  rtems_fdisk_info (fd, " queue-seg:%02d-%03d: p=%d a=%d u=%d b=%d f=%s n=%s",
                    sc->device, sc->segment,
                    sc->pages, sc->pages_active, sc->pages_used, sc->pages_bad,
                    sc->failed ? "FAILED" : "no", sc->next ? "set" : "null");
#endif

  /*
   * If the segment has failed then check the failed queue and append
   * if not failed.
   */
  if (sc->failed)
  {
    if (!rtems_fdisk_segment_queue_present (&fd->failed, sc))
      rtems_fdisk_segment_queue_push_tail (&fd->failed, sc);
    return;
  }

  /*
   * Remove the queue from the available or used queue.
   */
  rtems_fdisk_segment_queue_remove (&fd->available, sc);
  rtems_fdisk_segment_queue_remove (&fd->used, sc);

  /*
   * Are all the pages in the segment used ?
   * If they are and the driver has been configured to background
   * erase place the segment on the used queue. If not configured
   * to background erase perform the erase now.
   *
   */
  if (rtems_fdisk_seg_pages_available (sc) == 0)
  {
    if (sc->pages_active)
    {
      /*
       * Keep the used queue sorted by the most number of used
       * pages. When we compact we want to move the pages into
       * a new segment and cover more than one segment.
       */
      rtems_fdisk_segment_ctl* seg = fd->used.head;

      while (seg)
      {
        if (sc->pages_used > seg->pages_used)
          break;
        seg = seg->next;
      }

      if (seg)
        rtems_fdisk_segment_queue_insert_before (&fd->used, seg, sc);
      else
        rtems_fdisk_segment_queue_push_tail (&fd->used, sc);
    }
    else
    {
      if ((fd->flags & RTEMS_FDISK_BACKGROUND_ERASE))
        rtems_fdisk_segment_queue_push_tail (&fd->erase, sc);
      else
        rtems_fdisk_erase_segment (fd, sc);
    }
  }
  else
  {
    /*
     * The segment has pages available so place back onto the
     * available list. The list is sorted from the least number
     * of available pages to the most. This approach means
     * the pages of a partially filled segment will be filled
     * before moving onto another emptier segment. This keeps
     * empty segments longer aiding compaction.
     *
     * The down side is the wear effect as a single segment
     * could be used more than segment. This will not be
     * addressed until wear support is added.
     *
     * @note Wear support can be added by having counts for
     * for the number of times a segment is erased. This
     * available list is then sorted on the least number
     * of available pages then empty segments are sorted
     * on the least number of erases the segment has.
     *
     * The erase count can be stored in specially flaged
     * pages and contain a counter (32bits?) and 32 bits
     * for each segment. When a segment is erased a
     * bit is cleared for that segment. When 32 erasers
     * has occurred the page is re-written to the flash
     * with all the counters updated with the number of
     * bits cleared and all bits set back to 1.
     */
    rtems_fdisk_segment_ctl* seg = fd->available.head;

    while (seg)
    {
      if (rtems_fdisk_seg_pages_available (sc) <
          rtems_fdisk_seg_pages_available (seg))
        break;
      seg = seg->next;
    }

    if (seg)
      rtems_fdisk_segment_queue_insert_before (&fd->available, seg, sc);
    else
      rtems_fdisk_segment_queue_push_tail (&fd->available, sc);
  }
}

static int
rtems_fdisk_recycle_segment (rtems_flashdisk*         fd,
                                    rtems_fdisk_segment_ctl* ssc,
                                    rtems_fdisk_segment_ctl* dsc,
                                    uint32_t *pages)
{
  int      ret;
  uint32_t spage;
  uint32_t used = 0;
  uint32_t active = 0;

  for (spage = 0; spage < ssc->pages; spage++)
  {
    rtems_fdisk_page_desc* spd = &ssc->page_descriptors[spage];

    if (!dsc && ssc->pages_active > 0)
    {
      rtems_fdisk_error ("recycle: no available dst segment");
      return EIO;
    }

    if (rtems_fdisk_page_desc_flags_set (spd, RTEMS_FDISK_PAGE_ACTIVE) &&
        !rtems_fdisk_page_desc_flags_set (spd, RTEMS_FDISK_PAGE_USED))
    {
      uint32_t               dst_pages;
      rtems_fdisk_page_desc* dpd;
      uint32_t               dpage;

      dpage = rtems_fdisk_seg_next_available_page (dsc);
      dpd   = &dsc->page_descriptors[dpage];

      active++;

      if (dpage >= dsc->pages)
      {
        rtems_fdisk_error ("recycle: %02d-%03d: " \
                           "no page desc available: %d",
                           dsc->device, dsc->segment,
                           rtems_fdisk_seg_pages_available (dsc));
        dsc->failed = true;
        rtems_fdisk_queue_segment (fd, dsc);
        rtems_fdisk_segment_queue_push_head (&fd->used, ssc);
        return EIO;
      }

#if RTEMS_FDISK_TRACE
      rtems_fdisk_info (fd, "recycle: %02d-%03d-%03d=>%02d-%03d-%03d",
                        ssc->device, ssc->segment, spage,
                        dsc->device, dsc->segment, dpage);
#endif
      ret = rtems_fdisk_seg_copy_page (fd, ssc,
                                       spage + ssc->pages_desc,
                                       dsc,
                                       dpage + dsc->pages_desc);
      if (ret)
      {
        rtems_fdisk_error ("recycle: %02d-%03d-%03d=>" \
                           "%02d-%03d-%03d: "             \
                           "copy page failed: %s (%d)",
                           ssc->device, ssc->segment, spage,
                           dsc->device, dsc->segment, dpage,
                           strerror (ret), ret);
        rtems_fdisk_queue_segment (fd, dsc);
        rtems_fdisk_segment_queue_push_head (&fd->used, ssc);
        return ret;
      }

      *dpd = *spd;

      ret = rtems_fdisk_seg_write_page_desc (fd,
                                             dsc,
                                             dpage, dpd);

      if (ret)
      {
        rtems_fdisk_error ("recycle: %02d-%03d-%03d=>"   \
                           "%02d-%03d-%03d: copy pd failed: %s (%d)",
                           ssc->device, ssc->segment, spage,
                           dsc->device, dsc->segment, dpage,
                           strerror (ret), ret);
        rtems_fdisk_queue_segment (fd, dsc);
        rtems_fdisk_segment_queue_push_head (&fd->used, ssc);
        return ret;
      }

      dsc->pages_active++;

      /*
       * No need to set the used bit on the source page as the
       * segment will be erased. Power down could be a problem.
       * We do the stats to make sure everything is as it should
       * be.
       */

      ssc->pages_active--;
      ssc->pages_used++;

      fd->blocks[spd->block].segment = dsc;
      fd->blocks[spd->block].page    = dpage;

      /*
       * Place the segment on to the correct queue.
       */
      rtems_fdisk_queue_segment (fd, dsc);

      /*
       * Get new destination segment if necessary.
       */
      dst_pages = rtems_fdisk_seg_pages_available (dsc);
      if (dst_pages == 0)
        dsc = rtems_fdisk_seg_most_available (&fd->available);

      (*pages)--;
    }
    else if (rtems_fdisk_page_desc_erased (spd))
    {
      --fd->erased_blocks;
    }
    else
    {
      used++;
    }
  }

#if RTEMS_FDISK_TRACE
  rtems_fdisk_printf (fd, "ssc end: %d-%d: p=%ld, a=%ld, u=%ld",
                      ssc->device, ssc->segment,
                      pages, active, used);
#endif
  if (ssc->pages_active != 0)
  {
    rtems_fdisk_error ("compacting: ssc pages not 0: %d",
                       ssc->pages_active);
  }

  ret = rtems_fdisk_erase_segment (fd, ssc);

  return ret;
}

/**
 * Compact the used segments to free what is available. Find the segment
 * with the most available number of pages and see if we have
 * used segments that will fit. The used queue is sorted on the least
 * number of active pages.
 */
static int
rtems_fdisk_compact (rtems_flashdisk* fd)
{
  int ret;
  rtems_fdisk_segment_ctl* dsc;
  rtems_fdisk_segment_ctl* ssc;
  uint32_t compacted_segs = 0;
  uint32_t pages;

  if (rtems_fdisk_is_erased_blocks_starvation (fd))
  {
#if RTEMS_FDISK_TRACE
    rtems_fdisk_printf (fd, " resolve starvation");
#endif

    ssc = rtems_fdisk_segment_queue_pop_head (&fd->used);
    if (!ssc)
      ssc = rtems_fdisk_segment_queue_pop_head (&fd->available);

    if (ssc)
    {
      dsc = rtems_fdisk_seg_most_available (&fd->available);
      if (dsc)
      {
        ret = rtems_fdisk_recycle_segment (fd, ssc, dsc, &pages);
        if (ret)
          return ret;
      }
      else
      {
        rtems_fdisk_error ("compacting: starvation");
        return EIO;
      }
    }
    else
    {
      rtems_fdisk_error ("compacting: nothing to recycle");
      return EIO;
    }
  }

  while (fd->used.head)
  {
    uint32_t                 dst_pages;
    uint32_t                 segments;

#if RTEMS_FDISK_TRACE
    rtems_fdisk_printf (fd, " compacting");
#endif

    dsc = rtems_fdisk_seg_most_available (&fd->available);

    if (dsc == 0)
    {
      rtems_fdisk_error ("compacting: no available segments to compact too");
      return EIO;
    }

    ssc = fd->used.head;
    dst_pages = rtems_fdisk_seg_pages_available (dsc);
    segments = 0;
    pages = 0;

#if RTEMS_FDISK_TRACE
    rtems_fdisk_printf (fd, " dsc:%02d-%03d: most available",
                        dsc->device, dsc->segment);
#endif

    /*
     * Count the number of segments that have active pages that fit into
     * the destination segment. Also limit the number of segments that
     * we handle during one compaction. A lower number means less aggressive
     * compaction or less delay when compacting but it may mean the disk
     * will fill.
     */

    while (ssc &&
           ((pages + ssc->pages_active) < dst_pages) &&
           ((compacted_segs + segments) < fd->compact_segs))
    {
      pages += ssc->pages_active;
      segments++;
      ssc = ssc->next;
    }

    /*
     * We need a source segment and have pages to copy and
     * compacting one segment to another is silly. Compaction needs
     * to free at least one more segment.
     */

    if (!ssc || (pages == 0) || ((compacted_segs + segments) == 1))
    {
#if RTEMS_FDISK_TRACE
      rtems_fdisk_printf (fd, " nothing to compact");
#endif
      break;
    }

#if RTEMS_FDISK_TRACE
    rtems_fdisk_printf (fd, " ssc scan: %d-%d: p=%ld, seg=%ld",
                        ssc->device, ssc->segment,
                        pages, segments);
#endif

    rtems_fdisk_segment_queue_remove (&fd->available, dsc);

    /*
     * We now copy the pages to the new segment.
     */

    while (pages)
    {
      ssc = rtems_fdisk_segment_queue_pop_head (&fd->used);

      if (ssc)
      {
        ret = rtems_fdisk_recycle_segment (fd, ssc, dsc, &pages);
        if (ret)
          return ret;
      }
    }

    compacted_segs += segments;
  }

  return 0;
}

/**
 * Recover the block mappings from the devices.
 */
static int
rtems_fdisk_recover_block_mappings (rtems_flashdisk* fd)
{
  uint32_t device;

  /*
   * Clear the queues.
   */
  rtems_fdisk_segment_queue_init (&fd->available);
  rtems_fdisk_segment_queue_init (&fd->used);
  rtems_fdisk_segment_queue_init (&fd->erase);
  rtems_fdisk_segment_queue_init (&fd->failed);

  /*
   * Clear the lock mappings.
   */
  memset (fd->blocks, 0, fd->block_count * sizeof (rtems_fdisk_block_ctl));

  /*
   * Scan each segment or each device recovering the valid pages.
   */
  fd->erased_blocks = 0;
  fd->starvation_threshold = 0;
  for (device = 0; device < fd->device_count; device++)
  {
    uint32_t segment;
    for (segment = 0; segment < fd->devices[device].segment_count; segment++)
    {
      rtems_fdisk_segment_ctl*        sc = &fd->devices[device].segments[segment];
      const rtems_fdisk_segment_desc* sd = sc->descriptor;
      rtems_fdisk_page_desc*          pd;
      uint32_t                        page;
      int                             ret;

#if RTEMS_FDISK_TRACE
      rtems_fdisk_info (fd, "recover-block-mappings:%02d-%03d", device, segment);
#endif

      sc->pages_desc = rtems_fdisk_page_desc_pages (sd, fd->block_size);
      sc->pages =
        rtems_fdisk_pages_in_segment (sd, fd->block_size) - sc->pages_desc;
      if (sc->pages > fd->starvation_threshold)
        fd->starvation_threshold = sc->pages;

      sc->pages_active = 0;
      sc->pages_used   = 0;
      sc->pages_bad    = 0;

      sc->failed = false;

      if (!sc->page_descriptors)
        sc->page_descriptors = malloc (sc->pages_desc * fd->block_size);

      if (!sc->page_descriptors)
        rtems_fdisk_abort ("no memory for page descriptors");

      pd = sc->page_descriptors;

      /*
       * The page descriptors are always at the start of the segment. Read
       * the descriptors off the device into the segment control page
       * descriptors.
       *
       * @todo It may be better to ask the driver to get these value
       *       so NAND flash could be better supported.
       */
      ret = rtems_fdisk_seg_read (fd, sc, 0, (void*) pd,
                                  sc->pages_desc * fd->block_size);

      if (ret)
      {
        rtems_fdisk_error ("recover-block-mappings:%02d-%03d: " \
                           "read page desc failed: %s (%d)",
                           device, segment, strerror (ret), ret);
        return ret;
      }

      /*
       * Check each page in the segement for valid pages.
       * Update the stats for the segment so we know how many pages
       * are active and how many are used.
       *
       * If the page is active see if the block is with-in range and
       * if the block is a duplicate.
       */
      for (page = 0; page < sc->pages; page++, pd++)
      {
        if (rtems_fdisk_page_desc_erased (pd))
        {
          /*
           * Is the page erased ?
           */
          ret = rtems_fdisk_seg_blank_check_page (fd, sc,
                                                  page + sc->pages_desc);

          if (ret == 0)
          {
            ++fd->erased_blocks;
          }
          else
          {
#if RTEMS_FDISK_TRACE
            rtems_fdisk_warning (fd, "page not blank: %d-%d-%d",
                                 device, segment, page, pd->block);
#endif
            rtems_fdisk_page_desc_set_flags (pd, RTEMS_FDISK_PAGE_USED);

            ret = rtems_fdisk_seg_write_page_desc (fd, sc,
                                                   page, pd);

            if (ret)
            {
              rtems_fdisk_error ("forcing page to used failed: %d-%d-%d",
                                 device, segment, page);
            }

            sc->pages_used++;
          }
        }
        else
        {
          if (rtems_fdisk_page_desc_flags_set (pd, RTEMS_FDISK_PAGE_USED))
          {
            sc->pages_used++;
          }
          else if (rtems_fdisk_page_desc_flags_set (pd, RTEMS_FDISK_PAGE_ACTIVE))
          {
            if (pd->block >= fd->block_count)
            {
#if RTEMS_FDISK_TRACE
              rtems_fdisk_warning (fd,
                                   "invalid block number: %d-%d-%d: block: %d",
                                   device, segment, page, pd->block);
#endif
              sc->pages_bad++;
            }
            else if (fd->blocks[pd->block].segment)
            {
              /**
               * @todo
               * This may need more work later. Maybe a counter is stored with
               * each block so we can tell which is the later block when
               * duplicates appear. A power down with a failed wirte could cause
               * a duplicate.
               */
              const rtems_fdisk_segment_ctl* bsc = fd->blocks[pd->block].segment;
              rtems_fdisk_error ("duplicate block: %d-%d-%d: " \
                                 "duplicate: %d-%d-%d",
                                 bsc->device, bsc->segment,
                                 fd->blocks[pd->block].page,
                                 device, segment, page);
              sc->pages_bad++;
            }
            else
            {
              /**
               * @todo
               * Add start up crc checks here.
               */
              fd->blocks[pd->block].segment = sc;
              fd->blocks[pd->block].page    = page;

              /*
               * The page is active.
               */
              sc->pages_active++;
            }
          }
          else
            sc->pages_bad++;
        }
      }

      /*
       * Place the segment on to the correct queue.
       */
      rtems_fdisk_queue_segment (fd, sc);
    }
  }

  return 0;
}

/**
 * Read a block. The block is checked to see if the page referenced
 * is valid and the page has a valid crc.
 *
 * @param fd The rtems_flashdisk control table.
 * @param block The block number to read.
 * @param buffer The buffer to write the data into.
 * @return 0 No error.
 * @return EIO Invalid block size, block number, segment pointer, crc,
 *             page flags.
 */
static bool
rtems_fdisk_read_block (rtems_flashdisk* fd,
                        uint32_t         block,
                        uint8_t*         buffer)
{
  rtems_fdisk_block_ctl*   bc;
  rtems_fdisk_segment_ctl* sc;
  rtems_fdisk_page_desc*   pd;

#if RTEMS_FDISK_TRACE
  rtems_fdisk_info (fd, "read-block:%d", block);
#endif

  /*
   * Broken out to allow info messages when testing.
   */

  if (block >= (fd->block_count - fd->unavail_blocks))
  {
    rtems_fdisk_error ("read-block: block out of range: %d", block);
    return EIO;
  }

  bc = &fd->blocks[block];

  if (!bc->segment)
  {
#if RTEMS_FDISK_TRACE
    rtems_fdisk_info (fd, "read-block: no segment mapping: %d", block);
#endif
    memset (buffer, 0xff, fd->block_size);
    return 0;
  }

  sc = fd->blocks[block].segment;
  pd = &sc->page_descriptors[bc->page];

#if RTEMS_FDISK_TRACE
  rtems_fdisk_info (fd,
                    " read:%d=>%02d-%03d-%03d: p=%d a=%d u=%d b=%d n=%s: " \
                    "f=%04x c=%04x b=%d",
                    block, sc->device, sc->segment, bc->page,
                    sc->pages, sc->pages_active, sc->pages_used, sc->pages_bad,
                    sc->next ? "set" : "null",
                    pd->flags, pd->crc, pd->block);
#endif

  if (rtems_fdisk_page_desc_flags_set (pd, RTEMS_FDISK_PAGE_ACTIVE))
  {
    if (rtems_fdisk_page_desc_flags_clear (pd, RTEMS_FDISK_PAGE_USED))
    {
      uint16_t cs;

      /*
       * We use the segment page offset not the page number used in the
       * driver. This skips the page descriptors.
       */
      int ret = rtems_fdisk_seg_read_page (fd, sc,
                                           bc->page + sc->pages_desc, buffer);

      if (ret)
      {
#if RTEMS_FDISK_TRACE
        rtems_fdisk_info (fd,
                          "read-block:%02d-%03d-%03d: read page failed: %s (%d)",
                          sc->device, sc->segment, bc->page,
                          strerror (ret), ret);
#endif
        return ret;
      }

      cs = rtems_fdisk_page_checksum (buffer, fd->block_size);

      if (cs == pd->crc)
        return 0;

      rtems_fdisk_error ("read-block: crc failure: %d: buffer:%04x page:%04x",
                         block, cs, pd->crc);
    }
    else
    {
      rtems_fdisk_error ("read-block: block points to used page: %d: %d-%d-%d",
                         block, sc->device, sc->segment, bc->page);
    }
  }
  else
  {
    rtems_fdisk_error ("read-block: block page not active: %d: %d-%d-%d",
                       block, sc->device, sc->segment, bc->page);
  }

  return EIO;
}

/**
 * Write a block. The block:
 *
 *  # May never have existed in flash before this write.
 *  # Exists and needs to be moved to a new page.
 *
 * If the block does not exist in flash we need to get the next
 * segment available to place the page into. The segments with
 * available pages are held on the avaliable list sorted on least
 * number of available pages as the primary key. Currently there
 * is no secondary key. Empty segments are at the end of the list.
 *
 * If the block already exists we need to set the USED bit in the
 * current page's flags. This is a single byte which changes a 1 to
 * a 0 and can be done with a single 16 bit write. The driver for
 * 8 bit devices should only attempt the write on the changed bit.
 *
 * @param fd The rtems_flashdisk control table.
 * @param block The block number to read.
 * @param block_size The size of the block. Must match what we have.
 * @param buffer The buffer to write the data into.
 * @return 0 No error.
 * @return EIO Invalid block size, block number, segment pointer, crc,
 *             page flags.
 */
static int
rtems_fdisk_write_block (rtems_flashdisk* fd,
                         uint32_t         block,
                         const uint8_t*   buffer)
{
  rtems_fdisk_block_ctl*   bc;
  rtems_fdisk_segment_ctl* sc;
  rtems_fdisk_page_desc*   pd;
  uint32_t                 page;
  int                      ret;

#if RTEMS_FDISK_TRACE
  rtems_fdisk_info (fd, "write-block:%d", block);
#endif

  /*
   * Broken out to allow info messages when testing.
   */

  if (block >= (fd->block_count - fd->unavail_blocks))
  {
    rtems_fdisk_error ("write-block: block out of range: %d", block);
    return EIO;
  }

  bc = &fd->blocks[block];

  /*
   * Does the page exist in flash ?
   */
  if (bc->segment)
  {
    sc = bc->segment;
    pd = &sc->page_descriptors[bc->page];

#if RTEMS_FDISK_TRACE
    rtems_fdisk_info (fd, " write:%02d-%03d-%03d: flag used",
                      sc->device, sc->segment, bc->page);
#endif

    /*
     * The page exists in flash so see if the page has been changed.
     */
    if (rtems_fdisk_seg_verify_page (fd, sc->device, sc->segment,
                                     bc->page + sc->pages_desc, buffer) == 0)
    {
#if RTEMS_FDISK_TRACE
      rtems_fdisk_info (fd, "write-block:%d=>%02d-%03d-%03d: page verified",
                        block, sc->device, sc->segment, bc->page);
#endif
      return 0;
    }

    /*
     * The page exists in flash so we need to set the used flag
     * in the page descriptor. The descriptor is in memory with the
     * segment control block. We can assume this memory copy
     * matches the flash device.
     */

    rtems_fdisk_page_desc_set_flags (pd, RTEMS_FDISK_PAGE_USED);

    ret = rtems_fdisk_seg_write_page_desc_flags (fd, sc, bc->page, pd);

    if (ret)
    {
#if RTEMS_FDISK_TRACE
      rtems_fdisk_info (fd, " write:%02d-%03d-%03d: "      \
                        "write used page desc failed: %s (%d)",
                        sc->device, sc->segment, bc->page,
                        strerror (ret), ret);
#endif
    }
    else
    {
      sc->pages_active--;
      sc->pages_used++;
    }

    /*
     * If possible reuse this segment. This will mean the segment
     * needs to be removed from the available list and placed
     * back if space is still available.
     */
    rtems_fdisk_queue_segment (fd, sc);

    /*
     * If no background compacting then compact in the forground.
     * If we compact we ignore the error as there is little we
     * can do from here. The write may will work.
     */
    if ((fd->flags & RTEMS_FDISK_BACKGROUND_COMPACT) == 0)
      rtems_fdisk_compact (fd);
  }

  /*
   * Is it time to compact the disk ?
   *
   * We override the background compaction configruation.
   */
  if (rtems_fdisk_segment_count_queue (&fd->available) <=
      fd->avail_compact_segs)
    rtems_fdisk_compact (fd);

  /*
   * Get the next avaliable segment.
   */
  sc = rtems_fdisk_segment_queue_pop_head (&fd->available);

  /*
   * Is the flash disk full ?
   */
  if (!sc)
  {
    /*
     * If compacting is configured for the background do it now
     * to see if we can get some space back.
     */
    if ((fd->flags & RTEMS_FDISK_BACKGROUND_COMPACT))
      rtems_fdisk_compact (fd);

    /*
     * Try again for some free space.
     */
    sc = rtems_fdisk_segment_queue_pop_head (&fd->available);

    if (!sc)
    {
      rtems_fdisk_error ("write-block: no available pages");
      return ENOSPC;
    }
  }

#if RTEMS_FDISK_TRACE
  if (fd->info_level >= 3)
  {
    char queues[5];
    rtems_fdisk_queue_status (fd, sc, queues);
    rtems_fdisk_info (fd, " write:%d=>%02d-%03d: queue check: %s",
                      block, sc->device, sc->segment, queues);
  }
#endif

  /*
   * Find the next avaliable page in the segment.
   */

  pd = sc->page_descriptors;

  for (page = 0; page < sc->pages; page++, pd++)
  {
    if (rtems_fdisk_page_desc_erased (pd))
    {
      pd->crc   = rtems_fdisk_page_checksum (buffer, fd->block_size);
      pd->block = block;

      bc->segment = sc;
      bc->page    = page;

      rtems_fdisk_page_desc_set_flags (pd, RTEMS_FDISK_PAGE_ACTIVE);

#if RTEMS_FDISK_TRACE
      rtems_fdisk_info (fd, " write:%d=>%02d-%03d-%03d: write: " \
                        "p=%d a=%d u=%d b=%d n=%s: f=%04x c=%04x b=%d",
                        block, sc->device, sc->segment, page,
                        sc->pages, sc->pages_active, sc->pages_used,
                        sc->pages_bad, sc->next ? "set" : "null",
                        pd->flags, pd->crc, pd->block);
#endif

      /*
       * We use the segment page offset not the page number used in the
       * driver. This skips the page descriptors.
       */
      ret = rtems_fdisk_seg_write_page (fd, sc, page + sc->pages_desc, buffer);
      if (ret)
      {
#if RTEMS_FDISK_TRACE
        rtems_fdisk_info (fd, "write-block:%02d-%03d-%03d: write page failed: " \
                          "%s (%d)", sc->device, sc->segment, page,
                          strerror (ret), ret);
#endif
      }
      else
      {
        ret = rtems_fdisk_seg_write_page_desc (fd, sc, page, pd);
        if (ret)
        {
#if RTEMS_FDISK_TRACE
          rtems_fdisk_info (fd, "write-block:%02d-%03d-%03d: "  \
                            "write page desc failed: %s (%d)",
                            sc->device, sc->segment, bc->page,
                            strerror (ret), ret);
#endif
        }
        else
        {
          sc->pages_active++;
        }
      }

      rtems_fdisk_queue_segment (fd, sc);

      if (rtems_fdisk_is_erased_blocks_starvation (fd))
        rtems_fdisk_compact (fd);

      return ret;
    }
  }

  rtems_fdisk_error ("write-block: no erased page descs in segment: %d-%d",
                     sc->device, sc->segment);

  sc->failed = true;
  rtems_fdisk_queue_segment (fd, sc);

  return EIO;
}

/**
 * Disk READ request handler. This primitive copies data from the
 * flash disk to the supplied buffer and invoke the callout function
 * to inform upper layer that reading is completed.
 *
 * @param req Pointer to the READ block device request info.
 * @retval 0 Always.  The request done callback contains the status.
 */
static int
rtems_fdisk_read (rtems_flashdisk* fd, rtems_blkdev_request* req)
{
  rtems_blkdev_sg_buffer* sg = req->bufs;
  uint32_t                buf;
  int                     ret = 0;

  for (buf = 0; (ret == 0) && (buf < req->bufnum); buf++, sg++)
  {
    uint8_t* data;
    uint32_t fb;
    uint32_t b;
    fb = sg->length / fd->block_size;
    data = sg->buffer;
    for (b = 0; b < fb; b++, data += fd->block_size)
    {
      ret = rtems_fdisk_read_block (fd, sg->block + b, data);
      if (ret)
        break;
    }
  }

  req->status = ret ? RTEMS_IO_ERROR : RTEMS_SUCCESSFUL;
  req->req_done (req->done_arg, req->status);

  return 0;
}

/**
 * Flash disk WRITE request handler. This primitive copies data from
 * supplied buffer to flash disk and invoke the callout function to inform
 * upper layer that writing is completed.
 *
 * @param req Pointers to the WRITE block device request info.
 * @retval 0 Always.  The request done callback contains the status.
 */
static int
rtems_fdisk_write (rtems_flashdisk* fd, rtems_blkdev_request* req)
{
  rtems_blkdev_sg_buffer* sg = req->bufs;
  uint32_t                buf;
  int                     ret = 0;

  for (buf = 0; (ret == 0) && (buf < req->bufnum); buf++, sg++)
  {
    uint8_t* data;
    uint32_t fb;
    uint32_t b;
    fb = sg->length / fd->block_size;
    data = sg->buffer;
    for (b = 0; b < fb; b++, data += fd->block_size)
    {
      ret = rtems_fdisk_write_block (fd, sg->block + b, data);
      if (ret)
        break;
    }
  }

  req->status = ret ? RTEMS_IO_ERROR : RTEMS_SUCCESSFUL;
  req->req_done (req->done_arg, req->status);

  return 0;
}

/**
 * Flash disk erase disk.
 *
 * @param fd The flashdisk data.
 * @retval int The ioctl return value.
 */
static int
rtems_fdisk_erase_disk (rtems_flashdisk* fd)
{
  uint32_t device;
  int      ret;

#if RTEMS_FDISK_TRACE
  rtems_fdisk_info (fd, "erase-disk");
#endif

  ret = rtems_fdisk_erase_flash (fd);

  if (ret == 0)
  {
    for (device = 0; device < fd->device_count; device++)
    {
      if (!fd->devices[device].segments)
        return ENOMEM;

      ret = rtems_fdisk_recover_block_mappings (fd);
      if (ret)
        break;
    }
  }

  return ret;
}

/**
 * Flash Disk Monitoring data is return in the monitoring data
 * structure.
 */
static int
rtems_fdisk_monitoring_data (rtems_flashdisk*          fd,
                             rtems_fdisk_monitor_data* data)
{
  uint32_t i;
  uint32_t j;

  data->block_size     = fd->block_size;
  data->block_count    = fd->block_count;
  data->unavail_blocks = fd->unavail_blocks;
  data->device_count   = fd->device_count;

  data->blocks_used = 0;
  for (i = 0; i < fd->block_count; i++)
    if (fd->blocks[i].segment)
      data->blocks_used++;

  data->segs_available = rtems_fdisk_segment_count_queue (&fd->available);
  data->segs_used      = rtems_fdisk_segment_count_queue (&fd->used);
  data->segs_failed    = rtems_fdisk_segment_count_queue (&fd->failed);

  data->segment_count = 0;
  data->page_count    = 0;
  data->pages_desc    = 0;
  data->pages_active  = 0;
  data->pages_used    = 0;
  data->pages_bad     = 0;
  data->seg_erases    = 0;

  for (i = 0; i < fd->device_count; i++)
  {
    data->segment_count += fd->devices[i].segment_count;

    for (j = 0; j < fd->devices[i].segment_count; j++)
    {
      rtems_fdisk_segment_ctl* sc = &fd->devices[i].segments[j];

      data->page_count   += sc->pages;
      data->pages_desc   += sc->pages_desc;
      data->pages_active += sc->pages_active;
      data->pages_used   += sc->pages_used;
      data->pages_bad    += sc->pages_bad;
      data->seg_erases   += sc->erased;
    }
  }

  data->info_level = fd->info_level;
  return 0;
}

/**
 * Print to stdout the status of the driver. This is a debugging aid.
 */
static int
rtems_fdisk_print_status (rtems_flashdisk* fd)
{
#if RTEMS_FDISK_TRACE
  uint32_t current_info_level = fd->info_level;
  uint32_t total;
  uint32_t count;
  uint32_t device;

  fd->info_level = 3;

  rtems_fdisk_printf (fd,
                      "Flash Disk Driver Status : %d.%d", fd->major, fd->minor);

  rtems_fdisk_printf (fd, "Block count\t%d", fd->block_count);
  rtems_fdisk_printf (fd, "Unavail blocks\t%d", fd->unavail_blocks);
  rtems_fdisk_printf (fd, "Starvation threshold\t%d", fd->starvation_threshold);
  rtems_fdisk_printf (fd, "Starvations\t%d", fd->starvations);
  count = rtems_fdisk_segment_count_queue (&fd->available);
  total = count;
  rtems_fdisk_printf (fd, "Available queue\t%ld (%ld)",
                      count, rtems_fdisk_segment_queue_count (&fd->available));
  count = rtems_fdisk_segment_count_queue (&fd->used);
  total += count;
  rtems_fdisk_printf (fd, "Used queue\t%ld (%ld)",
                      count, rtems_fdisk_segment_queue_count (&fd->used));
  count = rtems_fdisk_segment_count_queue (&fd->erase);
  total += count;
  rtems_fdisk_printf (fd, "Erase queue\t%ld (%ld)",
                      count, rtems_fdisk_segment_queue_count (&fd->erase));
  count = rtems_fdisk_segment_count_queue (&fd->failed);
  total += count;
  rtems_fdisk_printf (fd, "Failed queue\t%ld (%ld)",
                      count, rtems_fdisk_segment_queue_count (&fd->failed));

  count = 0;
  for (device = 0; device < fd->device_count; device++)
    count += fd->devices[device].segment_count;

  rtems_fdisk_printf (fd, "Queue total\t%ld of %ld, %s", total, count,
                      total == count ? "ok" : "MISSING");

  rtems_fdisk_printf (fd, "Device count\t%d", fd->device_count);

  for (device = 0; device < fd->device_count; device++)
  {
    uint32_t block;
    uint32_t seg;

    rtems_fdisk_printf (fd, " Device\t\t%ld", device);
    rtems_fdisk_printf (fd, "  Segment count\t%ld",
                        fd->devices[device].segment_count);

    for (seg = 0; seg < fd->devices[device].segment_count; seg++)
    {
      rtems_fdisk_segment_ctl* sc = &fd->devices[device].segments[seg];
      uint32_t                 page;
      uint32_t                 erased = 0;
      uint32_t                 active = 0;
      uint32_t                 used = 0;
      bool                     is_active = false;
      char                     queues[5];

      rtems_fdisk_queue_status (fd, sc, queues);

      for (page = 0; page < sc->pages; page++)
      {
        if (rtems_fdisk_page_desc_erased (&sc->page_descriptors[page]))
          erased++;
        else if (rtems_fdisk_page_desc_flags_set (&sc->page_descriptors[page],
                                                  RTEMS_FDISK_PAGE_ACTIVE))
        {
          if (rtems_fdisk_page_desc_flags_set (&sc->page_descriptors[page],
                                               RTEMS_FDISK_PAGE_USED))
            used++;
          else
          {
            active++;
            is_active = true;
          }
        }

        for (block = 0; block < fd->block_count; block++)
        {
          if ((fd->blocks[block].segment == sc) &&
              (fd->blocks[block].page == page) && !is_active)
            rtems_fdisk_printf (fd,
                                "    %ld\t not active when mapped by block %ld",
                                page, block);
        }
      }

      count = 0;
      for (block = 0; block < fd->block_count; block++)
      {
        if (fd->blocks[block].segment == sc)
          count++;
      }

      rtems_fdisk_printf (fd, "  %3ld %s p:%3ld a:%3ld/%3ld" \
                          " u:%3ld/%3ld e:%3ld/%3ld br:%ld",
                          seg, queues,
                          sc->pages, sc->pages_active, active,
                          sc->pages_used, used, erased,
                          sc->pages - (sc->pages_active +
                                       sc->pages_used + sc->pages_bad),
                          count);
    }
  }

  {
    rtems_fdisk_segment_ctl* sc = fd->used.head;
    int count = 0;
    rtems_fdisk_printf (fd, "Used List:");
    while (sc)
    {
      rtems_fdisk_printf (fd, "  %3d %02d:%03d u:%3ld",
                          count, sc->device, sc->segment, sc->pages_used);
      sc = sc->next;
      count++;
    }
  }
  fd->info_level = current_info_level;

  return 0;
#else
  return ENOSYS;
#endif
}

/**
 * Flash disk IOCTL handler.
 *
 * @param dd Disk device.
 * @param req IOCTL request code.
 * @param argp IOCTL argument.
 * @retval The IOCTL return value
 */
static int
rtems_fdisk_ioctl (rtems_disk_device *dd, uint32_t req, void* argp)
{
  dev_t                     dev = rtems_disk_get_device_identifier (dd);
  rtems_device_minor_number minor = rtems_filesystem_dev_minor_t (dev);
  rtems_blkdev_request*     r = argp;
  rtems_status_code         sc;

  errno = 0;

  sc = rtems_semaphore_obtain (rtems_flashdisks[minor].lock, RTEMS_WAIT, 0);
  if (sc != RTEMS_SUCCESSFUL)
    errno = EIO;
  else
  {
    errno = 0;
    switch (req)
    {
      case RTEMS_BLKIO_REQUEST:
        if ((minor >= rtems_flashdisk_count) ||
            (rtems_flashdisks[minor].device_count == 0))
        {
          errno = ENODEV;
        }
        else
        {
          switch (r->req)
          {
            case RTEMS_BLKDEV_REQ_READ:
              errno = rtems_fdisk_read (&rtems_flashdisks[minor], r);
              break;

            case RTEMS_BLKDEV_REQ_WRITE:
              errno = rtems_fdisk_write (&rtems_flashdisks[minor], r);
              break;

            default:
              errno = EINVAL;
              break;
          }
        }
        break;

      case RTEMS_FDISK_IOCTL_ERASE_DISK:
        errno = rtems_fdisk_erase_disk (&rtems_flashdisks[minor]);
        break;

      case RTEMS_FDISK_IOCTL_COMPACT:
        errno = rtems_fdisk_compact (&rtems_flashdisks[minor]);
        break;

      case RTEMS_FDISK_IOCTL_ERASE_USED:
        errno = rtems_fdisk_erase_used (&rtems_flashdisks[minor]);
        break;

      case RTEMS_FDISK_IOCTL_MONITORING:
        errno = rtems_fdisk_monitoring_data (&rtems_flashdisks[minor],
                                             (rtems_fdisk_monitor_data*) argp);
        break;

      case RTEMS_FDISK_IOCTL_INFO_LEVEL:
        rtems_flashdisks[minor].info_level = (uintptr_t) argp;
        break;

      case RTEMS_FDISK_IOCTL_PRINT_STATUS:
        errno = rtems_fdisk_print_status (&rtems_flashdisks[minor]);
        break;

      default:
        rtems_blkdev_ioctl (dd, req, argp);
        break;
    }

    sc = rtems_semaphore_release (rtems_flashdisks[minor].lock);
    if (sc != RTEMS_SUCCESSFUL)
      errno = EIO;
  }

  return errno == 0 ? 0 : -1;
}

/**
 * Flash disk device driver initialization.
 *
 * @todo Memory clean up on error is really badly handled.
 *
 * @param major Flash disk major device number.
 * @param minor Minor device number, not applicable.
 * @param arg Initialization argument, not applicable.
 */
rtems_device_driver
rtems_fdisk_initialize (rtems_device_major_number major,
                        rtems_device_minor_number minor,
                        void*                     arg __attribute__((unused)))
{
  const rtems_flashdisk_config* c = rtems_flashdisk_configuration;
  rtems_flashdisk*              fd;
  rtems_status_code             sc;

  sc = rtems_disk_io_initialize ();
  if (sc != RTEMS_SUCCESSFUL)
    return sc;

  sc = rtems_fdisk_crc16_gen_factors (0x8408);
  if (sc != RTEMS_SUCCESSFUL)
      return sc;

  rtems_flashdisks = calloc (rtems_flashdisk_configuration_size,
                             sizeof (rtems_flashdisk));

  if (!rtems_flashdisks)
    return RTEMS_NO_MEMORY;

  for (minor = 0; minor < rtems_flashdisk_configuration_size; minor++, c++)
  {
    char     name[] = RTEMS_FLASHDISK_DEVICE_BASE_NAME "a";
    dev_t    dev = rtems_filesystem_make_dev_t (major, minor);
    uint32_t device;
    uint32_t blocks = 0;
    int      ret;

    fd = &rtems_flashdisks[minor];

    name [sizeof(RTEMS_FLASHDISK_DEVICE_BASE_NAME)] += minor;

    fd->major              = major;
    fd->minor              = minor;
    fd->flags              = c->flags;
    fd->compact_segs       = c->compact_segs;
    fd->avail_compact_segs = c->avail_compact_segs;
    fd->block_size         = c->block_size;
    fd->unavail_blocks     = c->unavail_blocks;
    fd->info_level         = c->info_level;

    for (device = 0; device < c->device_count; device++)
      blocks += rtems_fdisk_blocks_in_device (&c->devices[device],
                                              c->block_size);

    /*
     * One copy buffer of a page size.
     */
    fd->copy_buffer = malloc (c->block_size);
    if (!fd->copy_buffer)
      return RTEMS_NO_MEMORY;

    fd->blocks = calloc (blocks, sizeof (rtems_fdisk_block_ctl));
    if (!fd->blocks)
      return RTEMS_NO_MEMORY;

    fd->block_count = blocks;

    fd->devices = calloc (c->device_count, sizeof (rtems_fdisk_device_ctl));
    if (!fd->devices)
      return RTEMS_NO_MEMORY;

    sc = rtems_semaphore_create (rtems_build_name ('F', 'D', 'S', 'K'), 1,
                                 RTEMS_PRIORITY | RTEMS_BINARY_SEMAPHORE |
                                 RTEMS_INHERIT_PRIORITY, 0, &fd->lock);
    if (sc != RTEMS_SUCCESSFUL)
    {
      rtems_fdisk_error ("disk lock create failed");
      free (fd->copy_buffer);
      free (fd->blocks);
      free (fd->devices);
      return sc;
    }

    sc = rtems_disk_create_phys(dev, c->block_size,
                                blocks - fd->unavail_blocks,
                                rtems_fdisk_ioctl, NULL, name);
    if (sc != RTEMS_SUCCESSFUL)
    {
      rtems_semaphore_delete (fd->lock);
      rtems_disk_delete (dev);
      free (fd->copy_buffer);
      free (fd->blocks);
      free (fd->devices);
      rtems_fdisk_error ("disk create phy failed");
      return sc;
    }

    for (device = 0; device < c->device_count; device++)
    {
      rtems_fdisk_segment_ctl* sc;
      uint32_t                 segment_count;
      uint32_t                 segment;

      segment_count = rtems_fdisk_count_segments (&c->devices[device]);

      fd->devices[device].segments = calloc (segment_count,
                                             sizeof (rtems_fdisk_segment_ctl));
      if (!fd->devices[device].segments)
      {
        rtems_disk_delete (dev);
        rtems_semaphore_delete (fd->lock);
        free (fd->copy_buffer);
        free (fd->blocks);
        free (fd->devices);
        return RTEMS_NO_MEMORY;
      }

      sc = fd->devices[device].segments;

      for (segment = 0; segment < c->devices[device].segment_count; segment++)
      {
        const rtems_fdisk_segment_desc* sd;
        uint32_t                        seg_segment;

        sd = &c->devices[device].segments[segment];

        for (seg_segment = 0; seg_segment < sd->count; seg_segment++, sc++)
        {
          sc->descriptor = sd;
          sc->device     = device;
          sc->segment    = seg_segment;
          sc->erased     = 0;
        }
      }

      fd->devices[device].segment_count = segment_count;
      fd->devices[device].descriptor    = &c->devices[device];
    }

    fd->device_count = c->device_count;

    ret = rtems_fdisk_recover_block_mappings (fd);
    if (ret)
    {
      rtems_disk_delete (dev);
      rtems_semaphore_delete (fd->lock);
      free (fd->copy_buffer);
      free (fd->blocks);
      free (fd->devices);
      rtems_fdisk_error ("recovery of disk failed: %s (%d)",
                         strerror (ret), ret);
      return ret;
    }

    ret = rtems_fdisk_compact (fd);
    if (ret)
    {
      rtems_disk_delete (dev);
      rtems_semaphore_delete (fd->lock);
      free (fd->copy_buffer);
      free (fd->blocks);
      free (fd->devices);
      rtems_fdisk_error ("compacting of disk failed: %s (%d)",
                         strerror (ret), ret);
      return ret;
    }
  }

  rtems_flashdisk_count = rtems_flashdisk_configuration_size;

  return RTEMS_SUCCESSFUL;
}