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
|
/* ckinit.c
*
* This file provides a template for the clock device driver initialization.
*
* COPYRIGHT (c) 1989-1999.
* On-Line Applications Research Corporation (OAR).
*
* The license and distribution terms for this file may be
* found in the file LICENSE in this distribution or at
* http://www.OARcorp.com/rtems/license.html.
*
* $Id$
*/
#include <stdlib.h>
#include <rtems.h>
#include <rtems/libio.h>
#include <bsp.h>
void Clock_exit( void );
rtems_isr Clock_isr( rtems_vector_number vector );
/*
* The interrupt vector number associated with the clock tick device
* driver.
*/
#define CLOCK_VECTOR PPC_IRQ_DECREMENTER
/*
* Clock_driver_ticks is a monotonically increasing counter of the
* number of clock ticks since the driver was initialized.
*/
volatile rtems_unsigned32 Clock_driver_ticks;
/*
* Clocks_per_tick is the number of clocks of the decrementer needed
* to fill BSP_Configuration.microseconds_per_tick.
*
* The clock rate is 1/4 the bus clock, or 16.666667 MHz, so:
*
* Clocks_per_tick = ((50/3)*1E6 clocks/sec) * (1 sec/1E6 us) * (X us/tick)
* = X * 50 / 3 clocks/tick
* where X = BSP_Configuration.microseconds_per_tick
*/
rtems_signed32 Clocks_per_tick;
/*
* These are set by clock driver during its init
*/
rtems_device_major_number rtems_clock_major = ~0;
rtems_device_minor_number rtems_clock_minor;
/*
* The previous ISR on this clock tick interrupt vector.
*/
rtems_isr_entry Old_ticker;
void Clock_exit( void );
/*
* Inline assembly routines to access the decrementer register
*/
static inline rtems_signed32 read_decrementer(void) {
rtems_signed32 result;
asm volatile ("mfdec %0" : "=r" (result) :);
return result;
}
static inline void write_decrementer(rtems_signed32 value) {
asm volatile ("mtdec %0" : : "r" (value));
}
/*
* Isr Handler
*/
rtems_isr Clock_isr(
rtems_vector_number vector
)
{
rtems_signed32 count, repeat = 0;
const rtems_signed32 period = Clocks_per_tick;
/*
* bump the number of clock driver ticks since initialization
*/
Clock_driver_ticks++;
/*
* be very paranoid and count number of "ticks" in case we missed some
*
* update the decrementer and signal rtems the appropriate number of times
*/
count = read_decrementer();
while (count < 0) {
count += period;
repeat++;
}
write_decrementer(count);
while (repeat-- > 0) {
rtems_clock_tick();
}
}
/*
* Install_clock
*
* Install a clock tick handler and reprograms the chip. This
* is used to initially establish the clock tick.
*/
void Install_clock(
rtems_isr_entry clock_isr
)
{
/*
* Initialize the clock tick device driver variables
*/
Clock_driver_ticks = 0;
switch (Falcon_SYSCR.SystemClock) {
case SYSCLK_50_MHZ:
Clocks_per_tick =
(BSP_Configuration.microseconds_per_tick * 25 + 1) / 2;
break;
case SYSCLK_60_MHZ:
Clocks_per_tick = BSP_Configuration.microseconds_per_tick * 15;
break;
case SYSCLK_67_MHZ:
Clocks_per_tick =
(BSP_Configuration.microseconds_per_tick * 50 + 1) / 3;
break;
}
/*
* If ticks_per_timeslice is configured as non-zero, then the user
* wants a clock tick.
*/
if ( BSP_Configuration.ticks_per_timeslice ) {
Old_ticker = (rtems_isr_entry) set_vector( clock_isr, CLOCK_VECTOR, 1 );
/*
* Hardware specific initialize goes here
*/
write_decrementer(Clocks_per_tick);
}
/*
* Schedule the clock cleanup routine to execute if the application exits.
*/
atexit( Clock_exit );
}
/*
* Clean up before the application exits
*/
void Clock_exit( void )
{
if ( BSP_Configuration.ticks_per_timeslice ) {
/* XXX: turn off the timer interrupts */
/* we can't really disable the timer without disabling all external
interupts. we'll slow down the decrementer to it's minimum speed. */
write_decrementer(~0);
/* XXX: If necessary, restore the old vector */
}
}
/*
* Clock_initialize
*
* Device driver entry point for clock tick driver initialization.
*/
rtems_device_driver Clock_initialize(
rtems_device_major_number major,
rtems_device_minor_number minor,
void *pargp
)
{
Install_clock( Clock_isr );
/*
* make major/minor avail to others such as shared memory driver
*/
rtems_clock_major = major;
rtems_clock_minor = minor;
return RTEMS_SUCCESSFUL;
}
rtems_device_driver Clock_control(
rtems_device_major_number major,
rtems_device_minor_number minor,
void *pargp
)
{
rtems_unsigned32 isrlevel;
rtems_libio_ioctl_args_t *args = pargp;
if (args == 0)
goto done;
/*
* This is hokey, but until we get a defined interface
* to do this, it will just be this simple...
*/
if (args->command == rtems_build_name('I', 'S', 'R', ' '))
{
Clock_isr(CLOCK_VECTOR);
}
else if (args->command == rtems_build_name('N', 'E', 'W', ' '))
{
rtems_interrupt_disable( isrlevel );
(void) set_vector( args->buffer, CLOCK_VECTOR, 1 );
rtems_interrupt_enable( isrlevel );
}
done:
return RTEMS_SUCCESSFUL;
}
|
