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Message-id: <80597ded-f4b4-2990-3eae-e72276296d1a@samsung.com>
Date: Mon, 12 Sep 2016 10:18:39 +0200
From: Jacek Anaszewski <j.anaszewski@...sung.com>
To: David Lechner <david@...hnology.com>,
Richard Purdie <rpurdie@...ys.net>
Cc: linux-kernel@...r.kernel.org, linux-leds@...r.kernel.org,
Marcel Holtmann <marcel@...tmann.org>
Subject: Re: [PATCH v3] leds: Introduce userspace leds driver
Hi David,
Thanks for addressing the issues. I've applied the patch to the
for-next branch of linux-leds.git, after making few more
modifications indicated below.
Thanks,
Jacek Anaszewski
On 09/09/2016 06:49 PM, David Lechner wrote:
> This driver creates a userspace leds driver similar to uinput.
s/leds/LED class/
Also in the commit title:
s/leds/LED class/
>
> New leds are created by opening /dev/uleds and writing a uleds_user_dev
s/leds/LED class devices/
> struct. A new leds class device is registered with the name given in the
s/leds/LED/
> struct. Reading will return a single byte that is the current brightness.
> The poll() syscall is also supported. It will be triggered whenever the
> brightness changes. Closing the file handle to /dev/uleds will remove
> the leds class device.
s/leds/LED/
>
> Signed-off-by: David Lechner <david@...hnology.com>
> ---
>
> v2 changes:
>
> * sort #includes
> * fix typo in Kconfig
> * Add Documentation text file
>
> v3 changes:
>
> * fix typos in docs
> * rename "leds class" to "LED class" in docs
> * rebase on linux-leds/for-next
>
>
> Documentation/leds/uleds.txt | 105 ++++++++++++++++++++
> drivers/leds/Kconfig | 8 ++
> drivers/leds/Makefile | 3 +
> drivers/leds/uleds.c | 224 +++++++++++++++++++++++++++++++++++++++++++
> include/uapi/linux/Kbuild | 1 +
> include/uapi/linux/uleds.h | 23 +++++
> 6 files changed, 364 insertions(+)
> create mode 100644 Documentation/leds/uleds.txt
> create mode 100644 drivers/leds/uleds.c
> create mode 100644 include/uapi/linux/uleds.h
>
> diff --git a/Documentation/leds/uleds.txt b/Documentation/leds/uleds.txt
> new file mode 100644
> index 0000000..de11dbb
> --- /dev/null
> +++ b/Documentation/leds/uleds.txt
> @@ -0,0 +1,105 @@
> +Userspace LEDs
> +==============
> +
> +The uleds driver supports userspace LEDs. This can be useful for testing
> +triggers and can also be used to implement virtual LEDs.
> +
> +
> +Usage
> +=====
> +
> +When the driver is loaded, a character device is created at /dev/uleds. To
> +create a new LED class device, open /dev/uleds and write a uleds_user_dev
> +structure to it (found in kernel public header file linux/uleds.h).
> +
> + #define ULEDS_MAX_NAME_SIZE 80
> +
> + struct uleds_user_dev {
> + char name[ULEDS_MAX_NAME_SIZE];
> + };
> +
> +A new LED class device will be created with the name given. The name can be
> +any valid file name, but consider using the LED class naming convention of
> +"devicename:color:function".
> +
> +The current brightness is found by reading a single byte from the character
> +device. Values are unsigned: 0 to 255. Reading does not block and always returns
> +the most recent brightness value. The device node can also be polled to notify
> +when the brightness value changes.
> +
> +The LED class device will be removed when the open file handle to /dev/uleds
> +is closed.
> +
> +
> +Example
> +=======
> +
> +/*
> + * uledmon.c
> + *
> + * This program creates a new userspace LED class device and monitors it. A
> + * timestamp and brightness value is printed each time the brightness changes.
> + *
> + * Usage: uledmon <device-name>
> + *
> + * <device-name> is the name of the LED class device to be created. Pressing
> + * CTRL+C will exit.
> + */
> +
> +#include <fcntl.h>
> +#include <poll.h>
> +#include <stdio.h>
> +#include <string.h>
> +#include <time.h>
> +#include <unistd.h>
> +
> +#include <linux/uleds.h>
> +
> +int main(int argc, char const *argv[])
> +{
> + struct uleds_user_dev uleds_dev;
> + int fd, ret;
> + struct pollfd pfd;
> + unsigned char brightness;
> + struct timespec ts;
> +
> + if (argc != 2) {
> + fprintf(stderr, "Requires <device-name> argument\n");
> + return 1;
> + }
> +
> + strncpy(uleds_dev.name, argv[1], ULEDS_MAX_NAME_SIZE);
> +
> + fd = open("/dev/uleds", O_RDWR);
> + if (fd == -1) {
> + perror("Failed to open /dev/uleds");
> + return 1;
> + }
> +
> + ret = write(fd, &uleds_dev, sizeof(uleds_dev));
> + if (ret == -1) {
> + perror("Failed to write to /dev/uleds");
> + close(fd);
> + return 1;
> + }
> +
> + pfd.fd = fd;
> + pfd.events = POLLIN;
> + pfd.revents = 0;
> +
> + while (!(pfd.revents & (POLLERR | POLLHUP | POLLNVAL))) {
> + ret = read(fd, &brightness, 1);
> + if (ret == -1) {
> + perror("Failed to read from /dev/uleds");
> + close(fd);
> + return 1;
> + }
> + clock_gettime(CLOCK_MONOTONIC, &ts);
> + printf("[%ld.%09ld] %u\n", ts.tv_sec, ts.tv_nsec, brightness);
> + poll(&pfd, 1, -1);
> + }
> +
> + close(fd);
> +
> + return 0;
> +}
> diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
> index 7a628c6..5fd3f4c 100644
> --- a/drivers/leds/Kconfig
> +++ b/drivers/leds/Kconfig
> @@ -659,6 +659,14 @@ config LEDS_MLXCPLD
> This option enabled support for the LEDs on the Mellanox
> boards. Say Y to enabled these.
>
> +config LEDS_USER
> + tristate "Userspace LED support"
> + depends on LEDS_CLASS
> + help
> + This option enables support for userspace LEDs. Say 'y' to enable this
> + support in kernel. To compile this driver as a module, choose 'm' here:
> + the module will be called uleds.
> +
> comment "LED Triggers"
> source "drivers/leds/trigger/Kconfig"
>
> diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
> index 3965070..d5331ff 100644
> --- a/drivers/leds/Makefile
> +++ b/drivers/leds/Makefile
> @@ -75,5 +75,8 @@ obj-$(CONFIG_LEDS_MLXCPLD) += leds-mlxcpld.o
> # LED SPI Drivers
> obj-$(CONFIG_LEDS_DAC124S085) += leds-dac124s085.o
>
> +# LED Userspace Drivers
> +obj-$(CONFIG_LEDS_USER) += uleds.o
> +
> # LED Triggers
> obj-$(CONFIG_LEDS_TRIGGERS) += trigger/
> diff --git a/drivers/leds/uleds.c b/drivers/leds/uleds.c
> new file mode 100644
> index 0000000..77a0bee
> --- /dev/null
> +++ b/drivers/leds/uleds.c
> @@ -0,0 +1,224 @@
> +/*
> + * Userspace driver for leds subsystem
s/leds subsystem/the LED subsystem/
> + *
> + * Copyright (C) 2016 David Lechner <david@...hnology.com>
> + *
> + * Based on uinput.c: Aristeu Sergio Rozanski Filho <aris@...hedrallabs.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;
> + unsigned char brightness;
> + unsigned char new_data;
> +};
> +
> +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 = 1;
> + 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.max_brightness = LED_FULL;
> + 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;
> + 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;
> + }
> +
> + if (!udev->user_dev.name[0]) {
> + ret = -EINVAL;
> + goto out;
> + }
> +
> + ret = led_classdev_register(NULL, &udev->led_cdev);
> + if (ret < 0)
> + goto out;
> +
> + 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 == 0)
> + return 0;
> +
> + if (count != 1)
> + return -EINVAL;
> +
> + 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 {
> + retval = copy_to_user(buffer, &udev->brightness, 1);
> + udev->new_data = 0;
> + retval = 1;
> + }
> +
> + mutex_unlock(&udev->mutex);
> +
> + if (retval || count == 0)
> + 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 unsigned int 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 POLLIN | POLLRDNORM;
> +
> + 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;
> + led_classdev_unregister(&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@...hnology.com>");
> +MODULE_DESCRIPTION("Userspace driver for leds subsystem");
s/leds subsystem/the LED subsystem/
> +MODULE_LICENSE("GPL");
> diff --git a/include/uapi/linux/Kbuild b/include/uapi/linux/Kbuild
> index 185f8ea..416f5e6 100644
> --- a/include/uapi/linux/Kbuild
> +++ b/include/uapi/linux/Kbuild
> @@ -421,6 +421,7 @@ header-y += udp.h
> header-y += uhid.h
> header-y += uinput.h
> header-y += uio.h
> +header-y += uleds.h
> header-y += ultrasound.h
> header-y += un.h
> header-y += unistd.h
> diff --git a/include/uapi/linux/uleds.h b/include/uapi/linux/uleds.h
> new file mode 100644
> index 0000000..e78ed46
> --- /dev/null
> +++ b/include/uapi/linux/uleds.h
> @@ -0,0 +1,23 @@
> +/*
> + * Userspace driver support for leds subsystem
s/leds subsystem/the LED subsystem/
> + *
> + * 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.
> + */
> +#ifndef _UAPI__ULEDS_H_
> +#define _UAPI__ULEDS_H_
> +
> +#define ULEDS_MAX_NAME_SIZE 80
> +
> +struct uleds_user_dev {
> + char name[ULEDS_MAX_NAME_SIZE];
> +};
> +
> +#endif /* _UAPI__ULEDS_H_ */
>
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