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path: root/drivers/scsi/device_handler/scsi_dh.c
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Diffstat (limited to 'drivers/scsi/device_handler/scsi_dh.c')
-rw-r--r--drivers/scsi/device_handler/scsi_dh.c162
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");