staging: line6: use default sysfs attribute macros

Move to use the DEVICE_ATTR_RW/RO macros, making it easier to audit the
sysfs file permissions, and get rid of the "empty" callback for
read-only files, saving lines of code.

Cc: Stefan Hajnoczi <stefanha@gmail.com>
Cc: Laurent Navet <laurent.navet@gmail.com>
Cc: Johannes Thumshirn <morbidrsa@googlemail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/line6/driver.c

@@ -567,15 +567,6 @@ ssize_t line6_nop_read(struct device *dev, struct device_attribute *attr,
 	return 0;
 }
 
-/*
-	No operation (i.e., unsupported).
-*/
-ssize_t line6_nop_write(struct device *dev, struct device_attribute *attr,
-			const char *buf, size_t count)
-{
-	return count;
-}
-
 /*
 	Generic destructor.
 */

drivers/staging/line6/driver.h

@@ -190,9 +190,6 @@ extern char *line6_alloc_sysex_buffer(struct usb_line6 *line6, int code1,
 				      int code2, int size);
 extern ssize_t line6_nop_read(struct device *dev,
 			      struct device_attribute *attr, char *buf);
-extern ssize_t line6_nop_write(struct device *dev,
-			       struct device_attribute *attr,
-			       const char *buf, size_t count);
 extern int line6_read_data(struct usb_line6 *line6, int address, void *data,
 			   size_t datalen);
 extern int line6_read_serial_number(struct usb_line6 *line6,

drivers/staging/line6/pcm.c

@@ -34,7 +34,7 @@ static struct snd_line6_pcm *dev2pcm(struct device *dev)
 /*
 	"read" request on "impulse_volume" special file.
 */
-static ssize_t pcm_get_impulse_volume(struct device *dev,
+static ssize_t impulse_volume_show(struct device *dev,
 				   struct device_attribute *attr, char *buf)
 {
 	return sprintf(buf, "%d\n", dev2pcm(dev)->impulse_volume);
@@ -43,7 +43,7 @@ static ssize_t pcm_get_impulse_volume(struct device *dev,
 /*
 	"write" request on "impulse_volume" special file.
 */
-static ssize_t pcm_set_impulse_volume(struct device *dev,
+static ssize_t impulse_volume_store(struct device *dev,
 				    struct device_attribute *attr,
 				    const char *buf, size_t count)
 {
@@ -64,11 +64,12 @@ static ssize_t pcm_set_impulse_volume(struct device *dev,
 
 	return count;
 }
+static DEVICE_ATTR_RW(impulse_volume);
 
 /*
 	"read" request on "impulse_period" special file.
 */
-static ssize_t pcm_get_impulse_period(struct device *dev,
+static ssize_t impulse_period_show(struct device *dev,
 				   struct device_attribute *attr, char *buf)
 {
 	return sprintf(buf, "%d\n", dev2pcm(dev)->impulse_period);
@@ -77,7 +78,7 @@ static ssize_t pcm_get_impulse_period(struct device *dev,
 /*
 	"write" request on "impulse_period" special file.
 */
-static ssize_t pcm_set_impulse_period(struct device *dev,
+static ssize_t impulse_period_store(struct device *dev,
 				    struct device_attribute *attr,
 				    const char *buf, size_t count)
 {
@@ -91,11 +92,7 @@ static ssize_t pcm_set_impulse_period(struct device *dev,
 	dev2pcm(dev)->impulse_period = value;
 	return count;
 }
-
-static DEVICE_ATTR(impulse_volume, S_IWUSR | S_IRUGO, pcm_get_impulse_volume,
-		   pcm_set_impulse_volume);
-static DEVICE_ATTR(impulse_period, S_IWUSR | S_IRUGO, pcm_get_impulse_period,
-		   pcm_set_impulse_period);
+static DEVICE_ATTR_RW(impulse_period);
 
 #endif
 

drivers/staging/line6/pod.c

@@ -192,7 +192,7 @@ static int pod_set_system_param_int(struct usb_line6_pod *pod, int value,
 /*
 	"read" request on "serial_number" special file.
 */
-static ssize_t pod_get_serial_number(struct device *dev,
+static ssize_t serial_number_show(struct device *dev,
 				  struct device_attribute *attr, char *buf)
 {
 	struct usb_interface *interface = to_usb_interface(dev);
@@ -203,9 +203,8 @@ static ssize_t pod_get_serial_number(struct device *dev,
 /*
 	"read" request on "firmware_version" special file.
 */
-static ssize_t pod_get_firmware_version(struct device *dev,
-					struct device_attribute *attr,
-					char *buf)
+static ssize_t firmware_version_show(struct device *dev,
+				     struct device_attribute *attr, char *buf)
 {
 	struct usb_interface *interface = to_usb_interface(dev);
 	struct usb_line6_pod *pod = usb_get_intfdata(interface);
@@ -216,7 +215,7 @@ static ssize_t pod_get_firmware_version(struct device *dev,
 /*
 	"read" request on "device_id" special file.
 */
-static ssize_t pod_get_device_id(struct device *dev,
+static ssize_t device_id_show(struct device *dev,
 			      struct device_attribute *attr, char *buf)
 {
 	struct usb_interface *interface = to_usb_interface(dev);
@@ -274,11 +273,9 @@ static void pod_startup4(struct work_struct *work)
 }
 
 /* POD special files: */
-static DEVICE_ATTR(device_id, S_IRUGO, pod_get_device_id, line6_nop_write);
-static DEVICE_ATTR(firmware_version, S_IRUGO, pod_get_firmware_version,
-		   line6_nop_write);
-static DEVICE_ATTR(serial_number, S_IRUGO, pod_get_serial_number,
-		   line6_nop_write);
+static DEVICE_ATTR_RO(device_id);
+static DEVICE_ATTR_RO(firmware_version);
+static DEVICE_ATTR_RO(serial_number);
 
 /* control info callback */
 static int snd_pod_control_monitor_info(struct snd_kcontrol *kcontrol,