ses: Add power_status to SES device slot

Add power_status to SES device slot, so we can power on/off the
HDDs behind the enclosure.

Check firmware status in ses_set_* before sending control pages to
firmware.

Signed-off-by: Song Liu <songliubraving@fb.com>
Acked-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Jens Axboe <axboe@fb.com>
Cc: Hannes Reinecke <hare@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>
diff --git a/drivers/misc/enclosure.c b/drivers/misc/enclosure.c
index b62314d..38552a3 100644
--- a/drivers/misc/enclosure.c
+++ b/drivers/misc/enclosure.c
@@ -148,6 +148,7 @@
 	for (i = 0; i < components; i++) {
 		edev->component[i].number = -1;
 		edev->component[i].slot = -1;
+		edev->component[i].power_status = 1;
 	}
 
 	mutex_lock(&container_list_lock);
@@ -583,6 +584,40 @@
 	return count;
 }
 
+static ssize_t get_component_power_status(struct device *cdev,
+					  struct device_attribute *attr,
+					  char *buf)
+{
+	struct enclosure_device *edev = to_enclosure_device(cdev->parent);
+	struct enclosure_component *ecomp = to_enclosure_component(cdev);
+
+	if (edev->cb->get_power_status)
+		edev->cb->get_power_status(edev, ecomp);
+	return snprintf(buf, 40, "%s\n", ecomp->power_status ? "on" : "off");
+}
+
+static ssize_t set_component_power_status(struct device *cdev,
+					  struct device_attribute *attr,
+					  const char *buf, size_t count)
+{
+	struct enclosure_device *edev = to_enclosure_device(cdev->parent);
+	struct enclosure_component *ecomp = to_enclosure_component(cdev);
+	int val;
+
+	if (strncmp(buf, "on", 2) == 0 &&
+	    (buf[2] == '\n' || buf[2] == '\0'))
+		val = 1;
+	else if (strncmp(buf, "off", 3) == 0 &&
+	    (buf[3] == '\n' || buf[3] == '\0'))
+		val = 0;
+	else
+		return -EINVAL;
+
+	if (edev->cb->set_power_status)
+		edev->cb->set_power_status(edev, ecomp, val);
+	return count;
+}
+
 static ssize_t get_component_type(struct device *cdev,
 				  struct device_attribute *attr, char *buf)
 {
@@ -614,6 +649,8 @@
 		   set_component_active);
 static DEVICE_ATTR(locate, S_IRUGO | S_IWUSR, get_component_locate,
 		   set_component_locate);
+static DEVICE_ATTR(power_status, S_IRUGO | S_IWUSR, get_component_power_status,
+		   set_component_power_status);
 static DEVICE_ATTR(type, S_IRUGO, get_component_type, NULL);
 static DEVICE_ATTR(slot, S_IRUGO, get_component_slot, NULL);
 
@@ -622,6 +659,7 @@
 	&dev_attr_status.attr,
 	&dev_attr_active.attr,
 	&dev_attr_locate.attr,
+	&dev_attr_power_status.attr,
 	&dev_attr_type.attr,
 	&dev_attr_slot.attr,
 	NULL