[PATCH] leds: uleds: make max_brightness configurable

[David Lechner]

This adds support for configuring max_brightness when setting up a
userspace LED device. It also requires changing the brightness value
returned from a single byte to an integer. Since the uleds driver has
not made it into the mainline kernel yet, this is not breaking userspace.

Signed-off-by: David Lechner <da...@lechnology.com>
---
 drivers/leds/uleds.c       | 16 +++++++++++-----
 include/uapi/linux/uleds.h |  1 +
 tools/leds/uledmon.c       |  5 +++--
 3 files changed, 15 insertions(+), 7 deletions(-)

diff --git a/drivers/leds/uleds.c b/drivers/leds/uleds.c
index 2bbc73a..5e9e8a1 100644
--- a/drivers/leds/uleds.c
+++ b/drivers/leds/uleds.c
@@ -39,7 +39,7 @@ struct uleds_device {
        struct mutex            mutex;
        enum uleds_state        state;
        wait_queue_head_t       waitq;
-       unsigned char           brightness;
+       int                     brightness;
        bool                    new_data;
 };
 
@@ -67,7 +67,6 @@ static int uleds_open(struct inode *inode, struct file *file)
                return -ENOMEM;
 
        udev->led_cdev.name = udev->user_dev.name;
-       udev->led_cdev.max_brightness = LED_FULL;
        udev->led_cdev.brightness_set = uleds_brightness_set;
 
        mutex_init(&udev->mutex);
@@ -117,6 +116,12 @@ static ssize_t uleds_write(struct file *file, const char 
__user *buffer,
                goto out;
        }
 
+       if (udev->user_dev.max_brightness <= 0) {
+               ret = -EINVAL;
+               goto out;
+       }
+       udev->led_cdev.max_brightness = udev->user_dev.max_brightness;
+
        ret = devm_led_classdev_register(uleds_misc.this_device,
                                         &udev->led_cdev);
        if (ret < 0)
@@ -138,7 +143,7 @@ static ssize_t uleds_read(struct file *file, char __user 
*buffer, size_t count,
        struct uleds_device *udev = file->private_data;
        ssize_t retval;
 
-       if (count == 0)
+       if (count < sizeof(udev->brightness))
                return 0;
 
        do {
@@ -151,9 +156,10 @@ static ssize_t uleds_read(struct file *file, char __user 
*buffer, size_t count,
                } else if (!udev->new_data && (file->f_flags & O_NONBLOCK)) {
                        retval = -EAGAIN;
                } else if (udev->new_data) {
-                       retval = copy_to_user(buffer, &udev->brightness, 1);
+                       retval = copy_to_user(buffer, &udev->brightness,
+                                             sizeof(udev->brightness));
                        udev->new_data = false;
-                       retval = 1;
+                       retval = sizeof(udev->brightness);
                }
 
                mutex_unlock(&udev->mutex);
diff --git a/include/uapi/linux/uleds.h b/include/uapi/linux/uleds.h
index 2545b79..3788d5e 100644
--- a/include/uapi/linux/uleds.h
+++ b/include/uapi/linux/uleds.h
@@ -18,6 +18,7 @@
 
 struct uleds_user_dev {
        char name[LEDS_MAX_NAME_SIZE];
+       int max_brightness;
 };
 
 #endif /* _UAPI__ULEDS_H_ */
diff --git a/tools/leds/uledmon.c b/tools/leds/uledmon.c
index 44d8634..163da85 100644
--- a/tools/leds/uledmon.c
+++ b/tools/leds/uledmon.c
@@ -22,7 +22,7 @@ int main(int argc, char const *argv[])
 {
        struct uleds_user_dev uleds_dev;
        int fd, ret;
-       unsigned char brightness;
+       int brightness;
        struct timespec ts;
 
        if (argc != 2) {
@@ -31,6 +31,7 @@ int main(int argc, char const *argv[])
        }
 
        strncpy(uleds_dev.name, argv[1], LEDS_MAX_NAME_SIZE);
+       uleds_dev.max_brightness = 100;
 
        fd = open("/dev/uleds", O_RDWR);
        if (fd == -1) {
@@ -46,7 +47,7 @@ int main(int argc, char const *argv[])
        }
 
        while (1) {
-               ret = read(fd, &brightness, 1);
+               ret = read(fd, &brightness, sizeof(brightness));
                if (ret == -1) {
                        perror("Failed to read from /dev/uleds");
                        close(fd);
-- 
2.7.4