diff options
Diffstat (limited to 'drivers/leds/uleds.c')
| -rw-r--r-- | drivers/leds/uleds.c | 235 |
1 files changed, 235 insertions, 0 deletions
diff --git a/drivers/leds/uleds.c b/drivers/leds/uleds.c new file mode 100644 index 000000000..0c43bfac9 --- /dev/null +++ b/drivers/leds/uleds.c @@ -0,0 +1,235 @@ +/* + * Userspace driver for the LED subsystem + * + * Copyright (C) 2016 David Lechner <david@lechnology.com> + * + * Based on uinput.c: Aristeu Sergio Rozanski Filho <aris@cathedrallabs.org> + * + * 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. + */ +#include <linux/fs.h> +#include <linux/init.h> +#include <linux/leds.h> +#include <linux/miscdevice.h> +#include <linux/module.h> +#include <linux/poll.h> +#include <linux/sched.h> +#include <linux/slab.h> + +#include <uapi/linux/uleds.h> + +#define ULEDS_NAME "uleds" + +enum uleds_state { + ULEDS_STATE_UNKNOWN, + ULEDS_STATE_REGISTERED, +}; + +struct uleds_device { + struct uleds_user_dev user_dev; + struct led_classdev led_cdev; + struct mutex mutex; + enum uleds_state state; + wait_queue_head_t waitq; + int brightness; + bool new_data; +}; + +static struct miscdevice uleds_misc; + +static void uleds_brightness_set(struct led_classdev *led_cdev, + enum led_brightness brightness) +{ + struct uleds_device *udev = container_of(led_cdev, struct uleds_device, + led_cdev); + + if (udev->brightness != brightness) { + udev->brightness = brightness; + udev->new_data = true; + wake_up_interruptible(&udev->waitq); + } +} + +static int uleds_open(struct inode *inode, struct file *file) +{ + struct uleds_device *udev; + + udev = kzalloc(sizeof(*udev), GFP_KERNEL); + if (!udev) + return -ENOMEM; + + udev->led_cdev.name = udev->user_dev.name; + udev->led_cdev.brightness_set = uleds_brightness_set; + + mutex_init(&udev->mutex); + init_waitqueue_head(&udev->waitq); + udev->state = ULEDS_STATE_UNKNOWN; + + file->private_data = udev; + nonseekable_open(inode, file); + + return 0; +} + +static ssize_t uleds_write(struct file *file, const char __user *buffer, + size_t count, loff_t *ppos) +{ + struct uleds_device *udev = file->private_data; + const char *name; + int ret; + + if (count == 0) + return 0; + + ret = mutex_lock_interruptible(&udev->mutex); + if (ret) + return ret; + + if (udev->state == ULEDS_STATE_REGISTERED) { + ret = -EBUSY; + goto out; + } + + if (count != sizeof(struct uleds_user_dev)) { + ret = -EINVAL; + goto out; + } + + if (copy_from_user(&udev->user_dev, buffer, + sizeof(struct uleds_user_dev))) { + ret = -EFAULT; + goto out; + } + + name = udev->user_dev.name; + if (!name[0] || !strcmp(name, ".") || !strcmp(name, "..") || + strchr(name, '/')) { + ret = -EINVAL; + 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) + goto out; + + udev->new_data = true; + udev->state = ULEDS_STATE_REGISTERED; + ret = count; + +out: + mutex_unlock(&udev->mutex); + + return ret; +} + +static ssize_t uleds_read(struct file *file, char __user *buffer, size_t count, + loff_t *ppos) +{ + struct uleds_device *udev = file->private_data; + ssize_t retval; + + if (count < sizeof(udev->brightness)) + return 0; + + do { + retval = mutex_lock_interruptible(&udev->mutex); + if (retval) + return retval; + + if (udev->state != ULEDS_STATE_REGISTERED) { + retval = -ENODEV; + } else if (!udev->new_data && (file->f_flags & O_NONBLOCK)) { + retval = -EAGAIN; + } else if (udev->new_data) { + retval = copy_to_user(buffer, &udev->brightness, + sizeof(udev->brightness)); + udev->new_data = false; + retval = sizeof(udev->brightness); + } + + mutex_unlock(&udev->mutex); + + if (retval) + break; + + if (!(file->f_flags & O_NONBLOCK)) + retval = wait_event_interruptible(udev->waitq, + udev->new_data || + udev->state != ULEDS_STATE_REGISTERED); + } while (retval == 0); + + return retval; +} + +static __poll_t uleds_poll(struct file *file, poll_table *wait) +{ + struct uleds_device *udev = file->private_data; + + poll_wait(file, &udev->waitq, wait); + + if (udev->new_data) + return EPOLLIN | EPOLLRDNORM; + + return 0; +} + +static int uleds_release(struct inode *inode, struct file *file) +{ + struct uleds_device *udev = file->private_data; + + if (udev->state == ULEDS_STATE_REGISTERED) { + udev->state = ULEDS_STATE_UNKNOWN; + devm_led_classdev_unregister(uleds_misc.this_device, + &udev->led_cdev); + } + kfree(udev); + + return 0; +} + +static const struct file_operations uleds_fops = { + .owner = THIS_MODULE, + .open = uleds_open, + .release = uleds_release, + .read = uleds_read, + .write = uleds_write, + .poll = uleds_poll, + .llseek = no_llseek, +}; + +static struct miscdevice uleds_misc = { + .fops = &uleds_fops, + .minor = MISC_DYNAMIC_MINOR, + .name = ULEDS_NAME, +}; + +static int __init uleds_init(void) +{ + return misc_register(&uleds_misc); +} +module_init(uleds_init); + +static void __exit uleds_exit(void) +{ + misc_deregister(&uleds_misc); +} +module_exit(uleds_exit); + +MODULE_AUTHOR("David Lechner <david@lechnology.com>"); +MODULE_DESCRIPTION("Userspace driver for the LED subsystem"); +MODULE_LICENSE("GPL"); |