diff options
Diffstat (limited to 'drivers/staging/meilhaus/medlock.c')
| -rw-r--r-- | drivers/staging/meilhaus/medlock.c | 195 |
1 files changed, 195 insertions, 0 deletions
diff --git a/drivers/staging/meilhaus/medlock.c b/drivers/staging/meilhaus/medlock.c new file mode 100644 index 000000000000..f649e3da4f05 --- /dev/null +++ b/drivers/staging/meilhaus/medlock.c @@ -0,0 +1,195 @@ +/** + * @file medlock.c + * + * @brief Implements the device lock class. + * @note Copyright (C) 2006 Meilhaus Electronic GmbH (support@meilhaus.de) + * @author Guenter Gebhardt + */ + +/* + * Copyright (C) 2007 Meilhaus Electronic GmbH (support@meilhaus.de) + * + * This file is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. + */ + +#include <linux/spinlock.h> + +#include "medefines.h" +#include "meerror.h" + +#include "medebug.h" +#include "meslist.h" +#include "mesubdevice.h" +#include "medlock.h" + +int me_dlock_enter(struct me_dlock *dlock, struct file *filep) +{ + PDEBUG_LOCKS("executed.\n"); + + spin_lock(&dlock->spin_lock); + + if ((dlock->filep) != NULL && (dlock->filep != filep)) { + PERROR("Device is locked by another process.\n"); + spin_unlock(&dlock->spin_lock); + return ME_ERRNO_LOCKED; + } + + dlock->count++; + + spin_unlock(&dlock->spin_lock); + + return ME_ERRNO_SUCCESS; +} + +int me_dlock_exit(struct me_dlock *dlock, struct file *filep) +{ + PDEBUG_LOCKS("executed.\n"); + + spin_lock(&dlock->spin_lock); + dlock->count--; + spin_unlock(&dlock->spin_lock); + + return ME_ERRNO_SUCCESS; +} + +int me_dlock_lock(struct me_dlock *dlock, + struct file *filep, int lock, int flags, me_slist_t * slist) +{ + int err = ME_ERRNO_SUCCESS; + int i; + me_subdevice_t *subdevice; + + PDEBUG_LOCKS("executed.\n"); + + spin_lock(&dlock->spin_lock); + + switch (lock) { + + case ME_LOCK_RELEASE: + if ((dlock->filep == filep) || (dlock->filep == NULL)) { + dlock->filep = NULL; + + /* Unlock all possibly locked subdevices. */ + + for (i = 0; i < me_slist_get_number_subdevices(slist); + i++) { + subdevice = me_slist_get_subdevice(slist, i); + + if (subdevice) + err = + subdevice-> + me_subdevice_lock_subdevice + (subdevice, filep, ME_LOCK_RELEASE, + flags); + else + err = ME_ERRNO_INTERNAL; + } + } + + break; + + case ME_LOCK_SET: + if (dlock->count) { + PERROR("Device is used by another process.\n"); + err = ME_ERRNO_USED; + } else if ((dlock->filep != NULL) && (dlock->filep != filep)) { + PERROR("Device is locked by another process.\n"); + err = ME_ERRNO_LOCKED; + } else if (dlock->filep == NULL) { + /* Check any subdevice is locked by another process. */ + + for (i = 0; i < me_slist_get_number_subdevices(slist); + i++) { + subdevice = me_slist_get_subdevice(slist, i); + + if (subdevice) { + if ((err = + subdevice-> + me_subdevice_lock_subdevice + (subdevice, filep, ME_LOCK_CHECK, + flags))) { + PERROR + ("A subdevice is locked by another process.\n"); + break; + } + } else { + err = ME_ERRNO_INTERNAL; + } + } + + /* If no subdevices are locked by other processes, + we can take ownership of the device. Otherwise we jump ahead. */ + if (!err) + dlock->filep = filep; + } + + break; + + case ME_LOCK_CHECK: + if (dlock->count) { + err = ME_ERRNO_USED; + } else if ((dlock->filep != NULL) && (dlock->filep != filep)) { + err = ME_ERRNO_LOCKED; + } else if (dlock->filep == NULL) { + for (i = 0; i < me_slist_get_number_subdevices(slist); + i++) { + subdevice = me_slist_get_subdevice(slist, i); + + if (subdevice) { + if ((err = + subdevice-> + me_subdevice_lock_subdevice + (subdevice, filep, ME_LOCK_CHECK, + flags))) { + PERROR + ("A subdevice is locked by another process.\n"); + break; + } + } else { + err = ME_ERRNO_INTERNAL; + } + } + } + + break; + + default: + PERROR("Invalid lock.\n"); + + err = ME_ERRNO_INVALID_LOCK; + + break; + } + + spin_unlock(&dlock->spin_lock); + + return err; +} + +void me_dlock_deinit(struct me_dlock *dlock) +{ + PDEBUG_LOCKS("executed.\n"); +} + +int me_dlock_init(me_dlock_t * dlock) +{ + PDEBUG_LOCKS("executed.\n"); + + dlock->filep = NULL; + dlock->count = 0; + spin_lock_init(&dlock->spin_lock); + + return 0; +} |