diff options
Diffstat (limited to 'drivers/scsi/device_handler/scsi_dh.c')
| -rw-r--r-- | drivers/scsi/device_handler/scsi_dh.c | 162 |
1 files changed, 162 insertions, 0 deletions
diff --git a/drivers/scsi/device_handler/scsi_dh.c b/drivers/scsi/device_handler/scsi_dh.c new file mode 100644 index 000000000000..ab6c21cd9689 --- /dev/null +++ b/drivers/scsi/device_handler/scsi_dh.c @@ -0,0 +1,162 @@ +/* + * SCSI device handler infrastruture. + * + * This program 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., + * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. + * + * Copyright IBM Corporation, 2007 + * Authors: + * Chandra Seetharaman <sekharan@us.ibm.com> + * Mike Anderson <andmike@linux.vnet.ibm.com> + */ + +#include <scsi/scsi_dh.h> +#include "../scsi_priv.h" + +static DEFINE_SPINLOCK(list_lock); +static LIST_HEAD(scsi_dh_list); + +static struct scsi_device_handler *get_device_handler(const char *name) +{ + struct scsi_device_handler *tmp, *found = NULL; + + spin_lock(&list_lock); + list_for_each_entry(tmp, &scsi_dh_list, list) { + if (!strcmp(tmp->name, name)) { + found = tmp; + break; + } + } + spin_unlock(&list_lock); + return found; +} + +static int scsi_dh_notifier_add(struct device *dev, void *data) +{ + struct scsi_device_handler *scsi_dh = data; + + scsi_dh->nb.notifier_call(&scsi_dh->nb, BUS_NOTIFY_ADD_DEVICE, dev); + return 0; +} + +/* + * scsi_register_device_handler - register a device handler personality + * module. + * @scsi_dh - device handler to be registered. + * + * Returns 0 on success, -EBUSY if handler already registered. + */ +int scsi_register_device_handler(struct scsi_device_handler *scsi_dh) +{ + int ret = -EBUSY; + struct scsi_device_handler *tmp; + + tmp = get_device_handler(scsi_dh->name); + if (tmp) + goto done; + + ret = bus_register_notifier(&scsi_bus_type, &scsi_dh->nb); + + bus_for_each_dev(&scsi_bus_type, NULL, scsi_dh, scsi_dh_notifier_add); + spin_lock(&list_lock); + list_add(&scsi_dh->list, &scsi_dh_list); + spin_unlock(&list_lock); + +done: + return ret; +} +EXPORT_SYMBOL_GPL(scsi_register_device_handler); + +static int scsi_dh_notifier_remove(struct device *dev, void *data) +{ + struct scsi_device_handler *scsi_dh = data; + + scsi_dh->nb.notifier_call(&scsi_dh->nb, BUS_NOTIFY_DEL_DEVICE, dev); + return 0; +} + +/* + * scsi_unregister_device_handler - register a device handler personality + * module. + * @scsi_dh - device handler to be unregistered. + * + * Returns 0 on success, -ENODEV if handler not registered. + */ +int scsi_unregister_device_handler(struct scsi_device_handler *scsi_dh) +{ + int ret = -ENODEV; + struct scsi_device_handler *tmp; + + tmp = get_device_handler(scsi_dh->name); + if (!tmp) + goto done; + + ret = bus_unregister_notifier(&scsi_bus_type, &scsi_dh->nb); + + bus_for_each_dev(&scsi_bus_type, NULL, scsi_dh, + scsi_dh_notifier_remove); + spin_lock(&list_lock); + list_del(&scsi_dh->list); + spin_unlock(&list_lock); + +done: + return ret; +} +EXPORT_SYMBOL_GPL(scsi_unregister_device_handler); + +/* + * scsi_dh_activate - activate the path associated with the scsi_device + * corresponding to the given request queue. + * @q - Request queue that is associated with the scsi_device to be + * activated. + */ +int scsi_dh_activate(struct request_queue *q) +{ + int err = 0; + unsigned long flags; + struct scsi_device *sdev; + struct scsi_device_handler *scsi_dh = NULL; + + spin_lock_irqsave(q->queue_lock, flags); + sdev = q->queuedata; + if (sdev && sdev->scsi_dh_data) + scsi_dh = sdev->scsi_dh_data->scsi_dh; + if (!scsi_dh || !get_device(&sdev->sdev_gendev)) + err = SCSI_DH_NOSYS; + spin_unlock_irqrestore(q->queue_lock, flags); + + if (err) + return err; + + if (scsi_dh->activate) + err = scsi_dh->activate(sdev); + put_device(&sdev->sdev_gendev); + return err; +} +EXPORT_SYMBOL_GPL(scsi_dh_activate); + +/* + * scsi_dh_handler_exist - Return TRUE(1) if a device handler exists for + * the given name. FALSE(0) otherwise. + * @name - name of the device handler. + */ +int scsi_dh_handler_exist(const char *name) +{ + return (get_device_handler(name) != NULL); +} +EXPORT_SYMBOL_GPL(scsi_dh_handler_exist); + +MODULE_DESCRIPTION("SCSI device handler"); +MODULE_AUTHOR("Chandra Seetharaman <sekharan@us.ibm.com>"); +MODULE_LICENSE("GPL"); |