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226 lines
4.7 KiB
226 lines
4.7 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* |
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* Userspace driver for the LED subsystem |
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* |
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* Copyright (C) 2016 David Lechner <[email protected]> |
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* |
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* Based on uinput.c: Aristeu Sergio Rozanski Filho <[email protected]> |
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*/ |
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#include <linux/fs.h> |
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#include <linux/init.h> |
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#include <linux/leds.h> |
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#include <linux/miscdevice.h> |
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#include <linux/module.h> |
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#include <linux/poll.h> |
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#include <linux/sched.h> |
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#include <linux/slab.h> |
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#include <uapi/linux/uleds.h> |
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#define ULEDS_NAME "uleds" |
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enum uleds_state { |
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ULEDS_STATE_UNKNOWN, |
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ULEDS_STATE_REGISTERED, |
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}; |
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struct uleds_device { |
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struct uleds_user_dev user_dev; |
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struct led_classdev led_cdev; |
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struct mutex mutex; |
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enum uleds_state state; |
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wait_queue_head_t waitq; |
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int brightness; |
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bool new_data; |
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}; |
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static struct miscdevice uleds_misc; |
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static void uleds_brightness_set(struct led_classdev *led_cdev, |
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enum led_brightness brightness) |
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{ |
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struct uleds_device *udev = container_of(led_cdev, struct uleds_device, |
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led_cdev); |
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if (udev->brightness != brightness) { |
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udev->brightness = brightness; |
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udev->new_data = true; |
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wake_up_interruptible(&udev->waitq); |
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} |
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} |
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static int uleds_open(struct inode *inode, struct file *file) |
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{ |
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struct uleds_device *udev; |
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udev = kzalloc(sizeof(*udev), GFP_KERNEL); |
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if (!udev) |
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return -ENOMEM; |
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udev->led_cdev.name = udev->user_dev.name; |
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udev->led_cdev.brightness_set = uleds_brightness_set; |
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mutex_init(&udev->mutex); |
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init_waitqueue_head(&udev->waitq); |
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udev->state = ULEDS_STATE_UNKNOWN; |
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file->private_data = udev; |
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stream_open(inode, file); |
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return 0; |
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} |
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static ssize_t uleds_write(struct file *file, const char __user *buffer, |
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size_t count, loff_t *ppos) |
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{ |
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struct uleds_device *udev = file->private_data; |
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const char *name; |
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int ret; |
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if (count == 0) |
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return 0; |
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ret = mutex_lock_interruptible(&udev->mutex); |
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if (ret) |
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return ret; |
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if (udev->state == ULEDS_STATE_REGISTERED) { |
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ret = -EBUSY; |
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goto out; |
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} |
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if (count != sizeof(struct uleds_user_dev)) { |
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ret = -EINVAL; |
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goto out; |
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} |
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if (copy_from_user(&udev->user_dev, buffer, |
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sizeof(struct uleds_user_dev))) { |
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ret = -EFAULT; |
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goto out; |
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} |
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name = udev->user_dev.name; |
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if (!name[0] || !strcmp(name, ".") || !strcmp(name, "..") || |
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strchr(name, '/')) { |
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ret = -EINVAL; |
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goto out; |
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} |
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if (udev->user_dev.max_brightness <= 0) { |
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ret = -EINVAL; |
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goto out; |
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} |
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udev->led_cdev.max_brightness = udev->user_dev.max_brightness; |
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ret = devm_led_classdev_register(uleds_misc.this_device, |
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&udev->led_cdev); |
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if (ret < 0) |
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goto out; |
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udev->new_data = true; |
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udev->state = ULEDS_STATE_REGISTERED; |
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ret = count; |
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out: |
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mutex_unlock(&udev->mutex); |
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return ret; |
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} |
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static ssize_t uleds_read(struct file *file, char __user *buffer, size_t count, |
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loff_t *ppos) |
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{ |
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struct uleds_device *udev = file->private_data; |
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ssize_t retval; |
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if (count < sizeof(udev->brightness)) |
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return 0; |
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do { |
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retval = mutex_lock_interruptible(&udev->mutex); |
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if (retval) |
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return retval; |
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if (udev->state != ULEDS_STATE_REGISTERED) { |
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retval = -ENODEV; |
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} else if (!udev->new_data && (file->f_flags & O_NONBLOCK)) { |
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retval = -EAGAIN; |
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} else if (udev->new_data) { |
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retval = copy_to_user(buffer, &udev->brightness, |
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sizeof(udev->brightness)); |
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udev->new_data = false; |
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retval = sizeof(udev->brightness); |
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} |
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mutex_unlock(&udev->mutex); |
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if (retval) |
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break; |
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if (!(file->f_flags & O_NONBLOCK)) |
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retval = wait_event_interruptible(udev->waitq, |
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udev->new_data || |
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udev->state != ULEDS_STATE_REGISTERED); |
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} while (retval == 0); |
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return retval; |
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} |
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static __poll_t uleds_poll(struct file *file, poll_table *wait) |
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{ |
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struct uleds_device *udev = file->private_data; |
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poll_wait(file, &udev->waitq, wait); |
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if (udev->new_data) |
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return EPOLLIN | EPOLLRDNORM; |
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return 0; |
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} |
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static int uleds_release(struct inode *inode, struct file *file) |
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{ |
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struct uleds_device *udev = file->private_data; |
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if (udev->state == ULEDS_STATE_REGISTERED) { |
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udev->state = ULEDS_STATE_UNKNOWN; |
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devm_led_classdev_unregister(uleds_misc.this_device, |
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&udev->led_cdev); |
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} |
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kfree(udev); |
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return 0; |
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} |
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static const struct file_operations uleds_fops = { |
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.owner = THIS_MODULE, |
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.open = uleds_open, |
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.release = uleds_release, |
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.read = uleds_read, |
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.write = uleds_write, |
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.poll = uleds_poll, |
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.llseek = no_llseek, |
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}; |
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static struct miscdevice uleds_misc = { |
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.fops = &uleds_fops, |
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.minor = MISC_DYNAMIC_MINOR, |
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.name = ULEDS_NAME, |
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}; |
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static int __init uleds_init(void) |
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{ |
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return misc_register(&uleds_misc); |
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} |
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module_init(uleds_init); |
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static void __exit uleds_exit(void) |
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{ |
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misc_deregister(&uleds_misc); |
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} |
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module_exit(uleds_exit); |
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MODULE_AUTHOR("David Lechner <[email protected]>"); |
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MODULE_DESCRIPTION("Userspace driver for the LED subsystem"); |
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MODULE_LICENSE("GPL");
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