NVMe: Export NVMe attributes to sysfs group

Adds all controller information to attribute list exposed to sysfs, and
appends the reset_controller attribute to it. The nvme device is created
with this attribute list, so driver no long manages its attributes.

Reported-by: Sujith Pandel <[e-mail]>
Cc: Sujith Pandel <sujithpshankar@ gmail.com>
Cc: David Milburn <[e-mail]>
Signed-off-by: Keith Busch <[e-mail]>
Signed-off-by: Jens Axboe <[e-mail]>

drivers/nvme/host/core.c

···
 	.is_visible	= nvme_attrs_are_visible,
 };
 
+#define nvme_show_function(field)						\
+static ssize_t  field##_show(struct device *dev,				\
+			    struct device_attribute *attr, char *buf)		\
+{										\
+        struct nvme_ctrl *ctrl = dev_get_drvdata(dev);				\
+        return sprintf(buf, "%.*s\n", (int)sizeof(ctrl->field), ctrl->field);	\
+}										\
+static DEVICE_ATTR(field, S_IRUGO, field##_show, NULL);
+
+nvme_show_function(model);
+nvme_show_function(serial);
+nvme_show_function(firmware_rev);
+
+static struct attribute *nvme_dev_attrs[] = {
+	&dev_attr_reset_controller.attr,
+	&dev_attr_model.attr,
+	&dev_attr_serial.attr,
+	&dev_attr_firmware_rev.attr,
+	NULL
+};
+
+static struct attribute_group nvme_dev_attrs_group = {
+	.attrs = nvme_dev_attrs,
+};
+
+static const struct attribute_group *nvme_dev_attr_groups[] = {
+	&nvme_dev_attrs_group,
+	NULL,
+};
+
 static int ns_cmp(void *priv, struct list_head *a, struct list_head *b)
 {
 	struct nvme_ns *nsa = container_of(a, struct nvme_ns, list);
···
 
 void nvme_uninit_ctrl(struct nvme_ctrl *ctrl)
  {
-	device_remove_file(ctrl->device, &dev_attr_reset_controller);
 	device_destroy(nvme_class, MKDEV(nvme_char_major, ctrl->instance));
 
 	spin_lock(&dev_list_lock);
···
 	if (ret)
 		goto out;
 
-	ctrl->device = device_create(nvme_class, ctrl->dev,
+	ctrl->device = device_create_with_groups(nvme_class, ctrl->dev,
 				MKDEV(nvme_char_major, ctrl->instance),
-				dev, "nvme%d", ctrl->instance);
+				dev, nvme_dev_attr_groups,
+				"nvme%d", ctrl->instance);
 	if (IS_ERR(ctrl->device)) {
 		ret = PTR_ERR(ctrl->device);
 		goto out_release_instance;
···
 	get_device(ctrl->device);
 	dev_set_drvdata(ctrl->device, ctrl);
 
-	ret = device_create_file(ctrl->device, &dev_attr_reset_controller);
-	if (ret)
-		goto out_put_device;
-
 	spin_lock(&dev_list_lock);
 	list_add_tail(&ctrl->node, &nvme_ctrl_list);
 	spin_unlock(&dev_list_lock);
 
 	return 0;
-
-out_put_device:
-	put_device(ctrl->device);
-	device_destroy(nvme_class, MKDEV(nvme_char_major, ctrl->instance));
 out_release_instance:
 	nvme_release_instance(ctrl);
 out: