/* $Id$ */ /* libi2c Implementation */ #if HAVE_CONFIG_H #include "config.h" #endif #include #include #include #include #include #include #include #include #include #define DRVNM "libi2c:" #define MAX_NO_BUSSES 8 /* Also limited by the macro building minor numbers */ #define MAX_NO_DRIVERS 16 /* Number of high level drivers we support */ #define MINOR2ADDR(minor) ((minor)&((1<<10)-1)) #define MINOR2BUS(minor) (((minor)>>10)&7) #define MINOR2DRV(minor) ((minor)>>13) /* Check the 'minor' argument, i.e., verify that * we have a driver connected */ #define DECL_CHECKED_BH(b, bh, m, s)\ unsigned b = MINOR2BUS(m); \ rtems_libi2c_bus_t *bh; \ if ( b >= MAX_NO_BUSSES || 0 == (bh=busses[b].bush) ) { \ return s RTEMS_INVALID_NUMBER; \ } #define DECL_CHECKED_DRV(d, b, m) \ unsigned d = MINOR2DRV(m); \ unsigned b = MINOR2BUS(m); \ if ( b >= MAX_NO_BUSSES || 0 == busses[b].bush \ || d > MAX_NO_DRIVERS || (d && 0 == drvs[d-1].drv )) {\ return RTEMS_INVALID_NUMBER; \ } #define DISPATCH(rval, entry, dflt) \ do { \ rtems_driver_address_table *ops = drvs[--drv].drv->ops; \ rval = ops->entry ? ops->entry(major,minor,arg) : dflt; \ } while (0) rtems_device_major_number rtems_libi2c_major; static struct i2cbus { rtems_libi2c_bus_t *bush; volatile rtems_id mutex; /* lock this across start -> stop */ volatile short waiting; volatile char started; char *name; } busses[MAX_NO_BUSSES] = { { 0 } }; static struct { rtems_libi2c_drv_t *drv; } drvs[MAX_NO_DRIVERS] = { { 0} }; static rtems_id libmutex = 0; #define LOCK(m) assert(!rtems_semaphore_obtain((m), RTEMS_WAIT, RTEMS_NO_TIMEOUT)) #define UNLOCK(m) rtems_semaphore_release((m)) #define LIBLOCK() LOCK(libmutex) #define LIBUNLOCK() UNLOCK(libmutex) #define MUTEX_ATTS \ ( RTEMS_PRIORITY \ | RTEMS_BINARY_SEMAPHORE \ |RTEMS_INHERIT_PRIORITY \ |RTEMS_NO_PRIORITY_CEILING \ |RTEMS_LOCAL ) static rtems_id mutexCreate (rtems_name nm) { rtems_status_code sc; rtems_id rval; if (RTEMS_SUCCESSFUL != (sc = rtems_semaphore_create (nm, 1, MUTEX_ATTS, 0, &rval))) { rtems_error (sc, DRVNM " unable to create mutex\n"); return 0; } return rval; } /* Lock a bus avoiding to have a mutex, which is mostly * unused, hanging around all the time. We just create * and delete it on the fly... * * ASSUMES: argument checked by caller */ static void lock_bus (int busno) { struct i2cbus *bus = &busses[busno]; LIBLOCK (); if (!bus->waiting) { /* nobody is holding the bus mutex - it's not there. Create it on the fly */ if (! (bus->mutex = mutexCreate (rtems_build_name ('i', '2', 'c', '0' + busno)))) { LIBUNLOCK (); rtems_panic (DRVNM " unable to create bus lock"); } } /* count number of people waiting on this bus; only the last one deletes the mutex */ bus->waiting++; LIBUNLOCK (); /* Now lock this bus */ LOCK (bus->mutex); } static void unlock_bus (int busno) { struct i2cbus *bus = &busses[busno]; LIBLOCK (); UNLOCK (bus->mutex); if (!--bus->waiting) { rtems_semaphore_delete (bus->mutex); } LIBUNLOCK (); } /* Note that 'arg' is always passed in as NULL */ static rtems_status_code i2c_init (rtems_device_major_number major, rtems_device_minor_number minor, void *arg) { rtems_status_code rval; DECL_CHECKED_DRV (drv, busno, minor) if (0 == drv) { rval = 0; } else { /* this is probably never called */ DISPATCH (rval, initialization_entry, RTEMS_SUCCESSFUL); } return rval; } static rtems_status_code i2c_open (rtems_device_major_number major, rtems_device_minor_number minor, void *arg) { rtems_status_code rval; DECL_CHECKED_DRV (drv, busno, minor) if (0 == drv) { rval = RTEMS_SUCCESSFUL; } else { DISPATCH (rval, open_entry, RTEMS_SUCCESSFUL); } return rval; } static rtems_status_code i2c_close (rtems_device_major_number major, rtems_device_minor_number minor, void *arg) { rtems_status_code rval; DECL_CHECKED_DRV (drv, busno, minor) if (0 == drv) { rval = RTEMS_SUCCESSFUL; } else { DISPATCH (rval, close_entry, RTEMS_SUCCESSFUL); } return rval; } static rtems_status_code i2c_read (rtems_device_major_number major, rtems_device_minor_number minor, void *arg) { int rval; /* int so we can check for negative value */ rtems_libio_rw_args_t *rwargs = arg; DECL_CHECKED_DRV (drv, busno, minor) if (0 == rwargs->count) { rwargs->bytes_moved = 0; return RTEMS_SUCCESSFUL; } if (0 == drv) { rval = rtems_libi2c_start_read_bytes (minor, (unsigned char *) rwargs->buffer, rwargs->count); if (rval >= 0) { rwargs->bytes_moved = rval; rtems_libi2c_send_stop (minor); rval = RTEMS_SUCCESSFUL; } else { rval = -rval; } } else { DISPATCH (rval, read_entry, RTEMS_NOT_IMPLEMENTED); } return rval; } static rtems_status_code i2c_write (rtems_device_major_number major, rtems_device_minor_number minor, void *arg) { int rval; /* int so we can check for negative value */ rtems_libio_rw_args_t *rwargs = arg; DECL_CHECKED_DRV (drv, busno, minor) if (0 == rwargs->count) { rwargs->bytes_moved = 0; return RTEMS_SUCCESSFUL; } if (0 == drv) { rval = rtems_libi2c_start_write_bytes (minor, (unsigned char *) rwargs->buffer, rwargs->count); if (rval >= 0) { rwargs->bytes_moved = rval; rtems_libi2c_send_stop (minor); rval = RTEMS_SUCCESSFUL; } else { rval = -rval; } } else { DISPATCH (rval, write_entry, RTEMS_NOT_IMPLEMENTED); } return rval; } static rtems_status_code i2c_ioctl (rtems_device_major_number major, rtems_device_minor_number minor, void *arg) { rtems_status_code rval; DECL_CHECKED_DRV (drv, busno, minor) if (0 == drv) { rval = RTEMS_NOT_IMPLEMENTED; } else { DISPATCH (rval, control_entry, RTEMS_NOT_IMPLEMENTED); } return rval; } /* Our ops just dispatch to the registered drivers */ static rtems_driver_address_table libi2c_io_ops = { initialization_entry: i2c_init, open_entry: i2c_open, close_entry: i2c_close, read_entry: i2c_read, write_entry: i2c_write, control_entry: i2c_ioctl, }; int rtems_libi2c_initialize () { rtems_status_code sc; if (!(libmutex = mutexCreate (rtems_build_name ('l', 'I', '2', 'C')))) return -1; sc = rtems_io_register_driver (0, &libi2c_io_ops, &rtems_libi2c_major); if (RTEMS_SUCCESSFUL != 0) { fprintf (stderr, DRVNM " Claiming driver slot failed (rtems status code %i)\n", sc); rtems_semaphore_delete (libmutex); libmutex = 0; return -1; } return 0; } int rtems_libi2c_register_bus (char *name, rtems_libi2c_bus_t * bus) { int i; rtems_status_code err; char *nmcpy = malloc (name ? strlen (name) + 1 : 20); char tmp, *chpt; struct stat sbuf; strcpy (nmcpy, name ? name : "/dev/i2c"); /* check */ if ('/' != *nmcpy) { fprintf (stderr, "Bad name; must be an absolute path starting with '/'\n"); return -RTEMS_INVALID_NAME; } /* file must not exist */ if (!stat (nmcpy, &sbuf)) { fprintf (stderr, "Bad name; file exists already\n"); return -RTEMS_INVALID_NAME; } /* we already verified that there is at least one '/' */ chpt = strrchr (nmcpy, '/') + 1; tmp = *chpt; *chpt = 0; i = stat (nmcpy, &sbuf); *chpt = tmp; if (i) { fprintf (stderr, "Bad name '%s'; parent directory doesn't exist\n", nmcpy); return -RTEMS_INVALID_NAME; } /* should be a directory since name terminates in '/' */ if (!libmutex) { fprintf (stderr, DRVNM " library not initialized\n"); return -RTEMS_NOT_DEFINED; } if (bus->size < sizeof (*bus)) { fprintf (stderr, DRVNM " bus-ops size too small -- misconfiguration?\n"); return -RTEMS_NOT_CONFIGURED; } LIBLOCK (); for (i = 0; i < MAX_NO_BUSSES; i++) { if (!busses[i].bush) { /* found a free slot */ busses[i].bush = bus; busses[i].mutex = 0; busses[i].waiting = 0; busses[i].started = 0; if (!name) sprintf (nmcpy + strlen (nmcpy), "%i", i); if ((err = busses[i].bush->ops->init (busses[i].bush))) { /* initialization failed */ i = -err; } else { busses[i].name = nmcpy;; nmcpy = 0; } break; } } LIBUNLOCK (); if (i >= MAX_NO_BUSSES) { i = -RTEMS_TOO_MANY; } free (nmcpy); return i; } static int not_started (int busno) { int rval; lock_bus (busno); rval = !busses[busno].started; unlock_bus (busno); return rval; } rtems_status_code rtems_libi2c_send_start (uint32_t minor) { int rval; DECL_CHECKED_BH (busno, bush, minor, +) lock_bus (busno); rval = bush->ops->send_start (bush); /* if this failed or is not the first start, unlock */ if (rval || busses[busno].started) { /* HMM - what to do if the 1st start failed ? * try to reset... */ if (!busses[busno].started) { /* just in case the bus driver fiddles with errno */ int errno_saved = errno; bush->ops->init (bush); errno = errno_saved; } else if (rval) { /* failed restart */ rtems_libi2c_send_stop (minor); } unlock_bus (busno); } else { /* successful 1st start; keep bus locked until stop is sent */ busses[busno].started = 1; } return rval; } rtems_status_code rtems_libi2c_send_stop (uint32_t minor) { rtems_status_code rval; DECL_CHECKED_BH (busno, bush, minor, +) if (not_started (busno)) return RTEMS_NOT_OWNER_OF_RESOURCE; rval = bush->ops->send_stop (bush); busses[busno].started = 0; unlock_bus (busno); return rval; } rtems_status_code rtems_libi2c_send_addr (uint32_t minor, int rw) { rtems_status_code sc; DECL_CHECKED_BH (busno, bush, minor, +) if (not_started (busno)) return RTEMS_NOT_OWNER_OF_RESOURCE; sc = bush->ops->send_addr (bush, MINOR2ADDR (minor), rw); if (RTEMS_SUCCESSFUL != sc) rtems_libi2c_send_stop (minor); return sc; } int rtems_libi2c_read_bytes (uint32_t minor, unsigned char *bytes, int nbytes) { int sc; DECL_CHECKED_BH (busno, bush, minor, -) if (not_started (busno)) return -RTEMS_NOT_OWNER_OF_RESOURCE; sc = bush->ops->read_bytes (bush, bytes, nbytes); if (sc < 0) rtems_libi2c_send_stop (minor); return sc; } int rtems_libi2c_write_bytes (uint32_t minor, unsigned char *bytes, int nbytes) { int sc; DECL_CHECKED_BH (busno, bush, minor, -) if (not_started (busno)) return -RTEMS_NOT_OWNER_OF_RESOURCE; sc = bush->ops->write_bytes (bush, bytes, nbytes); if (sc < 0) rtems_libi2c_send_stop (minor); return sc; } static int do_s_rw (uint32_t minor, unsigned char *bytes, int nbytes, int rw) { rtems_status_code sc; rtems_libi2c_bus_t *bush; if ((sc = rtems_libi2c_send_start (minor))) return -sc; /* at this point, we hold the bus and are sure the minor number is valid */ bush = busses[MINOR2BUS (minor)].bush; if ((sc = bush->ops->send_addr (bush, MINOR2ADDR (minor), rw))) { rtems_libi2c_send_stop (minor); return -sc; } if (rw) sc = bush->ops->read_bytes (bush, bytes, nbytes); else sc = bush->ops->write_bytes (bush, bytes, nbytes); if (sc < 0) { rtems_libi2c_send_stop (minor); } return sc; } int rtems_libi2c_start_read_bytes (uint32_t minor, unsigned char *bytes, int nbytes) { return do_s_rw (minor, bytes, nbytes, 1); } int rtems_libi2c_start_write_bytes (uint32_t minor, unsigned char *bytes, int nbytes) { return do_s_rw (minor, bytes, nbytes, 0); } int rtems_libi2c_register_drv (char *name, rtems_libi2c_drv_t * drvtbl, unsigned busno, unsigned i2caddr) { int i; rtems_status_code err; rtems_device_minor_number minor; if (!libmutex) { fprintf (stderr, DRVNM " library not initialized\n"); return -RTEMS_NOT_DEFINED; } if (name && strchr (name, '/')) { fprintf (stderr, "Invalid name: '%s' -- must not contain '/'\n", name); return -RTEMS_INVALID_NAME; } if (busno >= MAX_NO_BUSSES || !busses[busno].bush || i2caddr >= 1 << 10) { errno = EINVAL; return -RTEMS_INVALID_NUMBER; } if (drvtbl->size < sizeof (*drvtbl)) { fprintf (stderr, DRVNM " drv-ops size too small -- misconfiguration?\n"); return -RTEMS_NOT_CONFIGURED; } /* allocate slot */ LIBLOCK (); for (i = 0; i < MAX_NO_DRIVERS; i++) { /* driver # 0 is special, it is the built-in raw driver */ if (!drvs[i].drv) { char *str; dev_t dev; uint32_t mode; /* found a free slot; encode slot + 1 ! */ minor = ((i + 1) << 13) | RTEMS_LIBI2C_MAKE_MINOR (busno, i2caddr); if (name) { str = malloc (strlen (busses[busno].name) + strlen (name) + 2); sprintf (str, "%s.%s", busses[busno].name, name); dev = rtems_filesystem_make_dev_t (rtems_libi2c_major, minor); mode = 0111 | S_IFCHR; if (drvtbl->ops->read_entry) mode |= 0444; if (drvtbl->ops->write_entry) mode |= 0222; /* note that 'umask' is applied to 'mode' */ if (mknod (str, mode, dev)) { fprintf (stderr, "Creating device node failed: %s; you can try to do it manually...\n", strerror (errno)); } free (str); } drvs[i].drv = drvtbl; if (drvtbl->ops->initialization_entry) err = drvs[i].drv->ops->initialization_entry (rtems_libi2c_major, minor, 0); else err = RTEMS_SUCCESSFUL; LIBUNLOCK (); return err ? -err : minor; } } LIBUNLOCK (); return -RTEMS_TOO_MANY; }