drivers/leds/leds-turris-omnia.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * CZ.NIC's Turris Omnia LEDs driver
  *
  * 2020, 2023 by Marek Behún <kabel@kernel.org>
  */

 #include <linux/i2c.h>
 #include <linux/led-class-multicolor.h>
 #include <linux/module.h>
 #include <linux/mutex.h>
 #include <linux/of.h>
 #include "leds.h"

 #define OMNIA_BOARD_LEDS	12
 #define OMNIA_LED_NUM_CHANNELS	3

 /* MCU controller commands at I2C address 0x2a */
 #define OMNIA_MCU_I2C_ADDR		0x2a

 #define CMD_GET_STATUS_WORD		0x01
 #define STS_FEATURES_SUPPORTED		BIT(2)

 #define CMD_GET_FEATURES		0x10
 #define FEAT_LED_GAMMA_CORRECTION	BIT(5)

 /* LED controller commands at I2C address 0x2b */
 #define CMD_LED_MODE			0x03
 #define CMD_LED_MODE_LED(l)		((l) & 0x0f)
 #define CMD_LED_MODE_USER		0x10

 #define CMD_LED_STATE			0x04
 #define CMD_LED_STATE_LED(l)		((l) & 0x0f)
 #define CMD_LED_STATE_ON		0x10

 #define CMD_LED_COLOR			0x05
 #define CMD_LED_SET_BRIGHTNESS		0x07
 #define CMD_LED_GET_BRIGHTNESS		0x08

 #define CMD_SET_GAMMA_CORRECTION	0x30
 #define CMD_GET_GAMMA_CORRECTION	0x31

 struct omnia_led {
 	struct led_classdev_mc mc_cdev;
 	struct mc_subled subled_info[OMNIA_LED_NUM_CHANNELS];
 	u8 cached_channels[OMNIA_LED_NUM_CHANNELS];
 	bool on, hwtrig;
 	int reg;
 };

 #define to_omnia_led(l)		container_of(l, struct omnia_led, mc_cdev)

 struct omnia_leds {
 	struct i2c_client *client;
 	struct mutex lock;
 	bool has_gamma_correction;
 	struct omnia_led leds[];
 };

 static int omnia_cmd_write_u8(const struct i2c_client *client, u8 cmd, u8 val)
 {
 	u8 buf[2] = { cmd, val };
 	int ret;

 	ret = i2c_master_send(client, buf, sizeof(buf));

 	return ret < 0 ? ret : 0;
 }

 static int omnia_cmd_read_raw(struct i2c_adapter *adapter, u8 addr, u8 cmd,
 			      void *reply, size_t len)
 {
 	struct i2c_msg msgs[2];
 	int ret;

 	msgs[0].addr = addr;
 	msgs[0].flags = 0;
 	msgs[0].len = 1;
 	msgs[0].buf = &cmd;
 	msgs[1].addr = addr;
 	msgs[1].flags = I2C_M_RD;
 	msgs[1].len = len;
 	msgs[1].buf = reply;

 	ret = i2c_transfer(adapter, msgs, ARRAY_SIZE(msgs));
 	if (likely(ret == ARRAY_SIZE(msgs)))
 		return 0;
 	else if (ret < 0)
 		return ret;
 	else
 		return -EIO;
 }

 static int omnia_cmd_read_u8(const struct i2c_client *client, u8 cmd)
 {
 	u8 reply;
 	int err;

 	err = omnia_cmd_read_raw(client->adapter, client->addr, cmd, &reply, 1);
 	if (err)
 		return err;

 	return reply;
 }

 static int omnia_led_send_color_cmd(const struct i2c_client *client,
 				    struct omnia_led *led)
 {
 	char cmd[5];
 	int ret;

 	cmd[0] = CMD_LED_COLOR;
 	cmd[1] = led->reg;
 	cmd[2] = led->subled_info[0].brightness;
 	cmd[3] = led->subled_info[1].brightness;
 	cmd[4] = led->subled_info[2].brightness;

 	/* Send the color change command */
 	ret = i2c_master_send(client, cmd, 5);
 	if (ret < 0)
 		return ret;

 	/* Cache the RGB channel brightnesses */
 	for (int i = 0; i < OMNIA_LED_NUM_CHANNELS; ++i)
 		led->cached_channels[i] = led->subled_info[i].brightness;

 	return 0;
 }

 /* Determine if the computed RGB channels are different from the cached ones */
 static bool omnia_led_channels_changed(struct omnia_led *led)
 {
 	for (int i = 0; i < OMNIA_LED_NUM_CHANNELS; ++i)
 		if (led->subled_info[i].brightness != led->cached_channels[i])
 			return true;

 	return false;
 }

 static int omnia_led_brightness_set_blocking(struct led_classdev *cdev,
 					     enum led_brightness brightness)
 {
 	struct led_classdev_mc *mc_cdev = lcdev_to_mccdev(cdev);
 	struct omnia_leds *leds = dev_get_drvdata(cdev->dev->parent);
 	struct omnia_led *led = to_omnia_led(mc_cdev);
 	int err = 0;

 	mutex_lock(&leds->lock);

 	/*
 	 * Only recalculate RGB brightnesses from intensities if brightness is
 	 * non-zero (if it is zero and the LED is in HW blinking mode, we use
 	 * max_brightness as brightness). Otherwise we won't be using them and
 	 * we can save ourselves some software divisions (Omnia's CPU does not
 	 * implement the division instruction).
 	 */
 	if (brightness || led->hwtrig) {
 		led_mc_calc_color_components(mc_cdev, brightness ?:
 						      cdev->max_brightness);

 		/*
 		 * Send color command only if brightness is non-zero and the RGB
 		 * channel brightnesses changed.
 		 */
 		if (omnia_led_channels_changed(led))
 			err = omnia_led_send_color_cmd(leds->client, led);
 	}

 	/*
 	 * Send on/off state change only if (bool)brightness changed and the LED
 	 * is not being blinked by HW.
 	 */
 	if (!err && !led->hwtrig && !brightness != !led->on) {
 		u8 state = CMD_LED_STATE_LED(led->reg);

 		if (brightness)
 			state |= CMD_LED_STATE_ON;

 		err = omnia_cmd_write_u8(leds->client, CMD_LED_STATE, state);
 		if (!err)
 			led->on = !!brightness;
 	}

 	mutex_unlock(&leds->lock);

 	return err;
 }

 static struct led_hw_trigger_type omnia_hw_trigger_type;

 static int omnia_hwtrig_activate(struct led_classdev *cdev)
 {
 	struct led_classdev_mc *mc_cdev = lcdev_to_mccdev(cdev);
 	struct omnia_leds *leds = dev_get_drvdata(cdev->dev->parent);
 	struct omnia_led *led = to_omnia_led(mc_cdev);
 	int err = 0;

 	mutex_lock(&leds->lock);

 	if (!led->on) {
 		/*
 		 * If the LED is off (brightness was set to 0), the last
 		 * configured color was not necessarily sent to the MCU.
 		 * Recompute with max_brightness and send if needed.
 		 */
 		led_mc_calc_color_components(mc_cdev, cdev->max_brightness);

 		if (omnia_led_channels_changed(led))
 			err = omnia_led_send_color_cmd(leds->client, led);
 	}

 	if (!err) {
 		/* Put the LED into MCU controlled mode */
 		err = omnia_cmd_write_u8(leds->client, CMD_LED_MODE,
 					 CMD_LED_MODE_LED(led->reg));
 		if (!err)
 			led->hwtrig = true;
 	}

 	mutex_unlock(&leds->lock);

 	return err;
 }

 static void omnia_hwtrig_deactivate(struct led_classdev *cdev)
 {
 	struct omnia_leds *leds = dev_get_drvdata(cdev->dev->parent);
 	struct omnia_led *led = to_omnia_led(lcdev_to_mccdev(cdev));
 	int err;

 	mutex_lock(&leds->lock);

 	led->hwtrig = false;

 	/* Put the LED into software mode */
 	err = omnia_cmd_write_u8(leds->client, CMD_LED_MODE,
 				 CMD_LED_MODE_LED(led->reg) |
 				 CMD_LED_MODE_USER);

 	mutex_unlock(&leds->lock);

 	if (err)
 		dev_err(cdev->dev, "Cannot put LED to software mode: %i\n",
 			err);
 }

 static struct led_trigger omnia_hw_trigger = {
 	.name		= "omnia-mcu",
 	.activate	= omnia_hwtrig_activate,
 	.deactivate	= omnia_hwtrig_deactivate,
 	.trigger_type	= &omnia_hw_trigger_type,
 };

 static int omnia_led_register(struct i2c_client *client, struct omnia_led *led,
 			      struct device_node *np)
 {
 	struct led_init_data init_data = {};
 	struct device *dev = &client->dev;
 	struct led_classdev *cdev;
 	int ret, color;

 	ret = of_property_read_u32(np, "reg", &led->reg);
 	if (ret || led->reg >= OMNIA_BOARD_LEDS) {
 		dev_warn(dev,
 			 "Node %pOF: must contain 'reg' property with values between 0 and %i\n",
 			 np, OMNIA_BOARD_LEDS - 1);
 		return 0;
 	}

 	ret = of_property_read_u32(np, "color", &color);
 	if (ret || color != LED_COLOR_ID_RGB) {
 		dev_warn(dev,
 			 "Node %pOF: must contain 'color' property with value LED_COLOR_ID_RGB\n",
 			 np);
 		return 0;
 	}

 	led->subled_info[0].color_index = LED_COLOR_ID_RED;
 	led->subled_info[1].color_index = LED_COLOR_ID_GREEN;
 	led->subled_info[2].color_index = LED_COLOR_ID_BLUE;

 	/* Initial color is white */
 	for (int i = 0; i < OMNIA_LED_NUM_CHANNELS; ++i) {
 		led->subled_info[i].intensity = 255;
 		led->subled_info[i].brightness = 255;
 		led->subled_info[i].channel = i;
 	}

 	led->mc_cdev.subled_info = led->subled_info;
 	led->mc_cdev.num_colors = OMNIA_LED_NUM_CHANNELS;

 	init_data.fwnode = &np->fwnode;

 	cdev = &led->mc_cdev.led_cdev;
 	cdev->max_brightness = 255;
 	cdev->brightness_set_blocking = omnia_led_brightness_set_blocking;
 	cdev->trigger_type = &omnia_hw_trigger_type;
 	/*
 	 * Use the omnia-mcu trigger as the default trigger. It may be rewritten
 	 * by LED class from the linux,default-trigger property.
 	 */
 	cdev->default_trigger = omnia_hw_trigger.name;

 	/* put the LED into software mode */
 	ret = omnia_cmd_write_u8(client, CMD_LED_MODE,
 				 CMD_LED_MODE_LED(led->reg) |
 				 CMD_LED_MODE_USER);
 	if (ret) {
 		dev_err(dev, "Cannot set LED %pOF to software mode: %i\n", np,
 			ret);
 		return ret;
 	}

 	/* disable the LED */
 	ret = omnia_cmd_write_u8(client, CMD_LED_STATE,
 				 CMD_LED_STATE_LED(led->reg));
 	if (ret) {
 		dev_err(dev, "Cannot set LED %pOF brightness: %i\n", np, ret);
 		return ret;
 	}

 	/* Set initial color and cache it */
 	ret = omnia_led_send_color_cmd(client, led);
 	if (ret < 0) {
 		dev_err(dev, "Cannot set LED %pOF initial color: %i\n", np,
 			ret);
 		return ret;
 	}

 	ret = devm_led_classdev_multicolor_register_ext(dev, &led->mc_cdev,
 							&init_data);
 	if (ret < 0) {
 		dev_err(dev, "Cannot register LED %pOF: %i\n", np, ret);
 		return ret;
 	}

 	return 1;
 }

 /*
  * On the front panel of the Turris Omnia router there is also a button which
  * can be used to control the intensity of all the LEDs at once, so that if they
  * are too bright, user can dim them.
  * The microcontroller cycles between 8 levels of this global brightness (from
  * 100% to 0%), but this setting can have any integer value between 0 and 100.
  * It is therefore convenient to be able to change this setting from software.
  * We expose this setting via a sysfs attribute file called "brightness". This
  * file lives in the device directory of the LED controller, not an individual
  * LED, so it should not confuse users.
  */
 static ssize_t brightness_show(struct device *dev, struct device_attribute *a,
 			       char *buf)
 {
 	struct i2c_client *client = to_i2c_client(dev);
 	int ret;

 	ret = omnia_cmd_read_u8(client, CMD_LED_GET_BRIGHTNESS);

 	if (ret < 0)
 		return ret;

 	return sysfs_emit(buf, "%d\n", ret);
 }

 static ssize_t brightness_store(struct device *dev, struct device_attribute *a,
 				const char *buf, size_t count)
 {
 	struct i2c_client *client = to_i2c_client(dev);
 	unsigned long brightness;
 	int err;

 	if (kstrtoul(buf, 10, &brightness))
 		return -EINVAL;

 	if (brightness > 100)
 		return -EINVAL;

 	err = omnia_cmd_write_u8(client, CMD_LED_SET_BRIGHTNESS, brightness);

 	return err ?: count;
 }
 static DEVICE_ATTR_RW(brightness);

 static ssize_t gamma_correction_show(struct device *dev,
 				     struct device_attribute *a, char *buf)
 {
 	struct i2c_client *client = to_i2c_client(dev);
 	struct omnia_leds *leds = i2c_get_clientdata(client);
 	int ret;

 	if (leds->has_gamma_correction) {
 		ret = omnia_cmd_read_u8(client, CMD_GET_GAMMA_CORRECTION);
 		if (ret < 0)
 			return ret;
 	} else {
 		ret = 0;
 	}

 	return sysfs_emit(buf, "%d\n", !!ret);
 }

 static ssize_t gamma_correction_store(struct device *dev,
 				      struct device_attribute *a,
 				      const char *buf, size_t count)
 {
 	struct i2c_client *client = to_i2c_client(dev);
 	struct omnia_leds *leds = i2c_get_clientdata(client);
 	bool val;
 	int err;

 	if (!leds->has_gamma_correction)
 		return -EOPNOTSUPP;

 	if (kstrtobool(buf, &val) < 0)
 		return -EINVAL;

 	err = omnia_cmd_write_u8(client, CMD_SET_GAMMA_CORRECTION, val);

 	return err ?: count;
 }
 static DEVICE_ATTR_RW(gamma_correction);

 static struct attribute *omnia_led_controller_attrs[] = {
 	&dev_attr_brightness.attr,
 	&dev_attr_gamma_correction.attr,
 	NULL,
 };
 ATTRIBUTE_GROUPS(omnia_led_controller);

 static int omnia_mcu_get_features(const struct i2c_client *client)
 {
 	u16 reply;
 	int err;

 	err = omnia_cmd_read_raw(client->adapter, OMNIA_MCU_I2C_ADDR,
 				 CMD_GET_STATUS_WORD, &reply, sizeof(reply));
 	if (err)
 		return err;

 	/* Check whether MCU firmware supports the CMD_GET_FEAUTRES command */
 	if (!(le16_to_cpu(reply) & STS_FEATURES_SUPPORTED))
 		return 0;

 	err = omnia_cmd_read_raw(client->adapter, OMNIA_MCU_I2C_ADDR,
 				 CMD_GET_FEATURES, &reply, sizeof(reply));
 	if (err)
 		return err;

 	return le16_to_cpu(reply);
 }

 static int omnia_leds_probe(struct i2c_client *client)
 {
 	struct device *dev = &client->dev;
 	struct device_node *np = dev_of_node(dev);
 	struct omnia_leds *leds;
 	struct omnia_led *led;
 	int ret, count;

 	count = of_get_available_child_count(np);
 	if (!count) {
 		dev_err(dev, "LEDs are not defined in device tree!\n");
 		return -ENODEV;
 	} else if (count > OMNIA_BOARD_LEDS) {
 		dev_err(dev, "Too many LEDs defined in device tree!\n");
 		return -EINVAL;
 	}

 	leds = devm_kzalloc(dev, struct_size(leds, leds, count), GFP_KERNEL);
 	if (!leds)
 		return -ENOMEM;

 	leds->client = client;
 	i2c_set_clientdata(client, leds);

 	ret = omnia_mcu_get_features(client);
 	if (ret < 0) {
 		dev_err(dev, "Cannot determine MCU supported features: %d\n",
 			ret);
 		return ret;
 	}

 	leds->has_gamma_correction = ret & FEAT_LED_GAMMA_CORRECTION;
 	if (!leds->has_gamma_correction) {
 		dev_info(dev,
 			 "Your board's MCU firmware does not support the LED gamma correction feature.\n");
 		dev_info(dev,
 			 "Consider upgrading MCU firmware with the omnia-mcutool utility.\n");
 	}

 	mutex_init(&leds->lock);

 	ret = devm_led_trigger_register(dev, &omnia_hw_trigger);
 	if (ret < 0) {
 		dev_err(dev, "Cannot register private LED trigger: %d\n", ret);
 		return ret;
 	}

 	led = &leds->leds[0];
 	for_each_available_child_of_node_scoped(np, child) {
 		ret = omnia_led_register(client, led, child);
 		if (ret < 0)
 			return ret;

 		led += ret;
 	}

 	return 0;
 }

 static void omnia_leds_remove(struct i2c_client *client)
 {
 	u8 buf[5];

 	/* put all LEDs into default (HW triggered) mode */
 	omnia_cmd_write_u8(client, CMD_LED_MODE,
 			   CMD_LED_MODE_LED(OMNIA_BOARD_LEDS));

 	/* set all LEDs color to [255, 255, 255] */
 	buf[0] = CMD_LED_COLOR;
 	buf[1] = OMNIA_BOARD_LEDS;
 	buf[2] = 255;
 	buf[3] = 255;
 	buf[4] = 255;

 	i2c_master_send(client, buf, 5);
 }

 static const struct of_device_id of_omnia_leds_match[] = {
 	{ .compatible = "cznic,turris-omnia-leds", },
 	{},
 };
 MODULE_DEVICE_TABLE(of, of_omnia_leds_match);

 static const struct i2c_device_id omnia_id[] = {
 	{ "omnia" },
 	{ }
 };
 MODULE_DEVICE_TABLE(i2c, omnia_id);

 static struct i2c_driver omnia_leds_driver = {
 	.probe		= omnia_leds_probe,
 	.remove		= omnia_leds_remove,
 	.id_table	= omnia_id,
 	.driver		= {
 		.name	= "leds-turris-omnia",
 		.of_match_table = of_omnia_leds_match,
 		.dev_groups = omnia_led_controller_groups,
 	},
 };

 module_i2c_driver(omnia_leds_driver);

 MODULE_AUTHOR("Marek Behun <kabel@kernel.org>");
 MODULE_DESCRIPTION("CZ.NIC's Turris Omnia LEDs");
 MODULE_LICENSE("GPL v2");
	// SPDX-License-Identifier: GPL-2.0
	/*
	* CZ.NIC's Turris Omnia LEDs driver
	*
	* 2020, 2023 by Marek Behún <kabel@kernel.org>
	*/

	#include <linux/i2c.h>
	#include <linux/led-class-multicolor.h>
	#include <linux/module.h>
	#include <linux/mutex.h>
	#include <linux/of.h>
	#include "leds.h"

	#define OMNIA_BOARD_LEDS 12
	#define OMNIA_LED_NUM_CHANNELS 3

	/* MCU controller commands at I2C address 0x2a */
	#define OMNIA_MCU_I2C_ADDR 0x2a

	#define CMD_GET_STATUS_WORD 0x01
	#define STS_FEATURES_SUPPORTED BIT(2)

	#define CMD_GET_FEATURES 0x10
	#define FEAT_LED_GAMMA_CORRECTION BIT(5)

	/* LED controller commands at I2C address 0x2b */
	#define CMD_LED_MODE 0x03
	#define CMD_LED_MODE_LED(l) ((l) & 0x0f)
	#define CMD_LED_MODE_USER 0x10

	#define CMD_LED_STATE 0x04
	#define CMD_LED_STATE_LED(l) ((l) & 0x0f)
	#define CMD_LED_STATE_ON 0x10

	#define CMD_LED_COLOR 0x05
	#define CMD_LED_SET_BRIGHTNESS 0x07
	#define CMD_LED_GET_BRIGHTNESS 0x08

	#define CMD_SET_GAMMA_CORRECTION 0x30
	#define CMD_GET_GAMMA_CORRECTION 0x31

	struct omnia_led {
	struct led_classdev_mc mc_cdev;
	struct mc_subled subled_info[OMNIA_LED_NUM_CHANNELS];
	u8 cached_channels[OMNIA_LED_NUM_CHANNELS];
	bool on, hwtrig;
	int reg;
	};

	#define to_omnia_led(l) container_of(l, struct omnia_led, mc_cdev)

	struct omnia_leds {
	struct i2c_client *client;
	struct mutex lock;
	bool has_gamma_correction;
	struct omnia_led leds[];
	};

	static int omnia_cmd_write_u8(const struct i2c_client *client, u8 cmd, u8 val)
	{
	u8 buf[2] = { cmd, val };
	int ret;

	ret = i2c_master_send(client, buf, sizeof(buf));

	return ret < 0 ? ret : 0;
	}

	static int omnia_cmd_read_raw(struct i2c_adapter *adapter, u8 addr, u8 cmd,
	void *reply, size_t len)
	{
	struct i2c_msg msgs[2];
	int ret;

	msgs[0].addr = addr;
	msgs[0].flags = 0;
	msgs[0].len = 1;
	msgs[0].buf = &cmd;
	msgs[1].addr = addr;
	msgs[1].flags = I2C_M_RD;
	msgs[1].len = len;
	msgs[1].buf = reply;

	ret = i2c_transfer(adapter, msgs, ARRAY_SIZE(msgs));
	if (likely(ret == ARRAY_SIZE(msgs)))
	return 0;
	else if (ret < 0)
	return ret;
	else
	return -EIO;
	}

	static int omnia_cmd_read_u8(const struct i2c_client *client, u8 cmd)
	{
	u8 reply;
	int err;

	err = omnia_cmd_read_raw(client->adapter, client->addr, cmd, &reply, 1);
	if (err)
	return err;

	return reply;
	}

	static int omnia_led_send_color_cmd(const struct i2c_client *client,
	struct omnia_led *led)
	{
	char cmd[5];
	int ret;

	cmd[0] = CMD_LED_COLOR;
	cmd[1] = led->reg;
	cmd[2] = led->subled_info[0].brightness;
	cmd[3] = led->subled_info[1].brightness;
	cmd[4] = led->subled_info[2].brightness;

	/* Send the color change command */
	ret = i2c_master_send(client, cmd, 5);
	if (ret < 0)
	return ret;

	/* Cache the RGB channel brightnesses */
	for (int i = 0; i < OMNIA_LED_NUM_CHANNELS; ++i)
	led->cached_channels[i] = led->subled_info[i].brightness;

	return 0;
	}

	/* Determine if the computed RGB channels are different from the cached ones */
	static bool omnia_led_channels_changed(struct omnia_led *led)
	{
	for (int i = 0; i < OMNIA_LED_NUM_CHANNELS; ++i)
	if (led->subled_info[i].brightness != led->cached_channels[i])
	return true;

	return false;
	}

	static int omnia_led_brightness_set_blocking(struct led_classdev *cdev,
	enum led_brightness brightness)
	{
	struct led_classdev_mc *mc_cdev = lcdev_to_mccdev(cdev);
	struct omnia_leds *leds = dev_get_drvdata(cdev->dev->parent);
	struct omnia_led *led = to_omnia_led(mc_cdev);
	int err = 0;

	mutex_lock(&leds->lock);

	/*
	* Only recalculate RGB brightnesses from intensities if brightness is
	* non-zero (if it is zero and the LED is in HW blinking mode, we use
	* max_brightness as brightness). Otherwise we won't be using them and
	* we can save ourselves some software divisions (Omnia's CPU does not
	* implement the division instruction).
	*/
	if (brightness \|\| led->hwtrig) {
	led_mc_calc_color_components(mc_cdev, brightness ?:
	cdev->max_brightness);

	/*
	* Send color command only if brightness is non-zero and the RGB
	* channel brightnesses changed.
	*/
	if (omnia_led_channels_changed(led))
	err = omnia_led_send_color_cmd(leds->client, led);
	}

	/*
	* Send on/off state change only if (bool)brightness changed and the LED
	* is not being blinked by HW.
	*/
	if (!err && !led->hwtrig && !brightness != !led->on) {
	u8 state = CMD_LED_STATE_LED(led->reg);

	if (brightness)
	state \|= CMD_LED_STATE_ON;

	err = omnia_cmd_write_u8(leds->client, CMD_LED_STATE, state);
	if (!err)
	led->on = !!brightness;
	}

	mutex_unlock(&leds->lock);

	return err;
	}

	static struct led_hw_trigger_type omnia_hw_trigger_type;

	static int omnia_hwtrig_activate(struct led_classdev *cdev)
	{
	struct led_classdev_mc *mc_cdev = lcdev_to_mccdev(cdev);
	struct omnia_leds *leds = dev_get_drvdata(cdev->dev->parent);
	struct omnia_led *led = to_omnia_led(mc_cdev);
	int err = 0;

	mutex_lock(&leds->lock);

	if (!led->on) {
	/*
	* If the LED is off (brightness was set to 0), the last
	* configured color was not necessarily sent to the MCU.
	* Recompute with max_brightness and send if needed.
	*/
	led_mc_calc_color_components(mc_cdev, cdev->max_brightness);

	if (omnia_led_channels_changed(led))
	err = omnia_led_send_color_cmd(leds->client, led);
	}

	if (!err) {
	/* Put the LED into MCU controlled mode */
	err = omnia_cmd_write_u8(leds->client, CMD_LED_MODE,
	CMD_LED_MODE_LED(led->reg));
	if (!err)
	led->hwtrig = true;
	}

	mutex_unlock(&leds->lock);

	return err;
	}

	static void omnia_hwtrig_deactivate(struct led_classdev *cdev)
	{
	struct omnia_leds *leds = dev_get_drvdata(cdev->dev->parent);
	struct omnia_led *led = to_omnia_led(lcdev_to_mccdev(cdev));
	int err;

	mutex_lock(&leds->lock);

	led->hwtrig = false;

	/* Put the LED into software mode */
	err = omnia_cmd_write_u8(leds->client, CMD_LED_MODE,
	CMD_LED_MODE_LED(led->reg) \|
	CMD_LED_MODE_USER);

	mutex_unlock(&leds->lock);

	if (err)
	dev_err(cdev->dev, "Cannot put LED to software mode: %i\n",
	err);
	}

	static struct led_trigger omnia_hw_trigger = {
	.name = "omnia-mcu",
	.activate = omnia_hwtrig_activate,
	.deactivate = omnia_hwtrig_deactivate,
	.trigger_type = &omnia_hw_trigger_type,
	};

	static int omnia_led_register(struct i2c_client client, struct omnia_led led,
	struct device_node *np)
	{
	struct led_init_data init_data = {};
	struct device *dev = &client->dev;
	struct led_classdev *cdev;
	int ret, color;

	ret = of_property_read_u32(np, "reg", &led->reg);
	if (ret \|\| led->reg >= OMNIA_BOARD_LEDS) {
	dev_warn(dev,
	"Node %pOF: must contain 'reg' property with values between 0 and %i\n",
	np, OMNIA_BOARD_LEDS - 1);
	return 0;
	}

	ret = of_property_read_u32(np, "color", &color);
	if (ret \|\| color != LED_COLOR_ID_RGB) {
	dev_warn(dev,
	"Node %pOF: must contain 'color' property with value LED_COLOR_ID_RGB\n",
	np);
	return 0;
	}

	led->subled_info[0].color_index = LED_COLOR_ID_RED;
	led->subled_info[1].color_index = LED_COLOR_ID_GREEN;
	led->subled_info[2].color_index = LED_COLOR_ID_BLUE;

	/* Initial color is white */
	for (int i = 0; i < OMNIA_LED_NUM_CHANNELS; ++i) {
	led->subled_info[i].intensity = 255;
	led->subled_info[i].brightness = 255;
	led->subled_info[i].channel = i;
	}

	led->mc_cdev.subled_info = led->subled_info;
	led->mc_cdev.num_colors = OMNIA_LED_NUM_CHANNELS;

	init_data.fwnode = &np->fwnode;

	cdev = &led->mc_cdev.led_cdev;
	cdev->max_brightness = 255;
	cdev->brightness_set_blocking = omnia_led_brightness_set_blocking;
	cdev->trigger_type = &omnia_hw_trigger_type;
	/*
	* Use the omnia-mcu trigger as the default trigger. It may be rewritten
	* by LED class from the linux,default-trigger property.
	*/
	cdev->default_trigger = omnia_hw_trigger.name;

	/* put the LED into software mode */
	ret = omnia_cmd_write_u8(client, CMD_LED_MODE,
	CMD_LED_MODE_LED(led->reg) \|
	CMD_LED_MODE_USER);
	if (ret) {
	dev_err(dev, "Cannot set LED %pOF to software mode: %i\n", np,
	ret);
	return ret;
	}

	/* disable the LED */
	ret = omnia_cmd_write_u8(client, CMD_LED_STATE,
	CMD_LED_STATE_LED(led->reg));
	if (ret) {
	dev_err(dev, "Cannot set LED %pOF brightness: %i\n", np, ret);
	return ret;
	}

	/* Set initial color and cache it */
	ret = omnia_led_send_color_cmd(client, led);
	if (ret < 0) {
	dev_err(dev, "Cannot set LED %pOF initial color: %i\n", np,
	ret);
	return ret;
	}

	ret = devm_led_classdev_multicolor_register_ext(dev, &led->mc_cdev,
	&init_data);
	if (ret < 0) {
	dev_err(dev, "Cannot register LED %pOF: %i\n", np, ret);
	return ret;
	}

	return 1;
	}

	/*
	* On the front panel of the Turris Omnia router there is also a button which
	* can be used to control the intensity of all the LEDs at once, so that if they
	* are too bright, user can dim them.
	* The microcontroller cycles between 8 levels of this global brightness (from
	* 100% to 0%), but this setting can have any integer value between 0 and 100.
	* It is therefore convenient to be able to change this setting from software.
	* We expose this setting via a sysfs attribute file called "brightness". This
	* file lives in the device directory of the LED controller, not an individual
	* LED, so it should not confuse users.
	*/
	static ssize_t brightness_show(struct device dev, struct device_attribute a,
	char *buf)
	{
	struct i2c_client *client = to_i2c_client(dev);
	int ret;

	ret = omnia_cmd_read_u8(client, CMD_LED_GET_BRIGHTNESS);

	if (ret < 0)
	return ret;

	return sysfs_emit(buf, "%d\n", ret);
	}

	static ssize_t brightness_store(struct device dev, struct device_attribute a,
	const char *buf, size_t count)
	{
	struct i2c_client *client = to_i2c_client(dev);
	unsigned long brightness;
	int err;

	if (kstrtoul(buf, 10, &brightness))
	return -EINVAL;

	if (brightness > 100)
	return -EINVAL;

	err = omnia_cmd_write_u8(client, CMD_LED_SET_BRIGHTNESS, brightness);

	return err ?: count;
	}
	static DEVICE_ATTR_RW(brightness);

	static ssize_t gamma_correction_show(struct device *dev,
	struct device_attribute a, char buf)
	{
	struct i2c_client *client = to_i2c_client(dev);
	struct omnia_leds *leds = i2c_get_clientdata(client);
	int ret;

	if (leds->has_gamma_correction) {
	ret = omnia_cmd_read_u8(client, CMD_GET_GAMMA_CORRECTION);
	if (ret < 0)
	return ret;
	} else {
	ret = 0;
	}

	return sysfs_emit(buf, "%d\n", !!ret);
	}

	static ssize_t gamma_correction_store(struct device *dev,
	struct device_attribute *a,
	const char *buf, size_t count)
	{
	struct i2c_client *client = to_i2c_client(dev);
	struct omnia_leds *leds = i2c_get_clientdata(client);
	bool val;
	int err;

	if (!leds->has_gamma_correction)
	return -EOPNOTSUPP;

	if (kstrtobool(buf, &val) < 0)
	return -EINVAL;

	err = omnia_cmd_write_u8(client, CMD_SET_GAMMA_CORRECTION, val);

	return err ?: count;
	}
	static DEVICE_ATTR_RW(gamma_correction);

	static struct attribute *omnia_led_controller_attrs[] = {
	&dev_attr_brightness.attr,
	&dev_attr_gamma_correction.attr,
	NULL,
	};
	ATTRIBUTE_GROUPS(omnia_led_controller);

	static int omnia_mcu_get_features(const struct i2c_client *client)
	{
	u16 reply;
	int err;

	err = omnia_cmd_read_raw(client->adapter, OMNIA_MCU_I2C_ADDR,
	CMD_GET_STATUS_WORD, &reply, sizeof(reply));
	if (err)
	return err;

	/* Check whether MCU firmware supports the CMD_GET_FEAUTRES command */
	if (!(le16_to_cpu(reply) & STS_FEATURES_SUPPORTED))
	return 0;

	err = omnia_cmd_read_raw(client->adapter, OMNIA_MCU_I2C_ADDR,
	CMD_GET_FEATURES, &reply, sizeof(reply));
	if (err)
	return err;

	return le16_to_cpu(reply);
	}

	static int omnia_leds_probe(struct i2c_client *client)
	{
	struct device *dev = &client->dev;
	struct device_node *np = dev_of_node(dev);
	struct omnia_leds *leds;
	struct omnia_led *led;
	int ret, count;

	count = of_get_available_child_count(np);
	if (!count) {
	dev_err(dev, "LEDs are not defined in device tree!\n");
	return -ENODEV;
	} else if (count > OMNIA_BOARD_LEDS) {
	dev_err(dev, "Too many LEDs defined in device tree!\n");
	return -EINVAL;
	}

	leds = devm_kzalloc(dev, struct_size(leds, leds, count), GFP_KERNEL);
	if (!leds)
	return -ENOMEM;

	leds->client = client;
	i2c_set_clientdata(client, leds);

	ret = omnia_mcu_get_features(client);
	if (ret < 0) {
	dev_err(dev, "Cannot determine MCU supported features: %d\n",
	ret);
	return ret;
	}

	leds->has_gamma_correction = ret & FEAT_LED_GAMMA_CORRECTION;
	if (!leds->has_gamma_correction) {
	dev_info(dev,
	"Your board's MCU firmware does not support the LED gamma correction feature.\n");
	dev_info(dev,
	"Consider upgrading MCU firmware with the omnia-mcutool utility.\n");
	}

	mutex_init(&leds->lock);

	ret = devm_led_trigger_register(dev, &omnia_hw_trigger);
	if (ret < 0) {
	dev_err(dev, "Cannot register private LED trigger: %d\n", ret);
	return ret;
	}

	led = &leds->leds[0];
	for_each_available_child_of_node_scoped(np, child) {
	ret = omnia_led_register(client, led, child);
	if (ret < 0)
	return ret;

	led += ret;
	}

	return 0;
	}

	static void omnia_leds_remove(struct i2c_client *client)
	{
	u8 buf[5];

	/* put all LEDs into default (HW triggered) mode */
	omnia_cmd_write_u8(client, CMD_LED_MODE,
	CMD_LED_MODE_LED(OMNIA_BOARD_LEDS));

	/* set all LEDs color to [255, 255, 255] */
	buf[0] = CMD_LED_COLOR;
	buf[1] = OMNIA_BOARD_LEDS;
	buf[2] = 255;
	buf[3] = 255;
	buf[4] = 255;

	i2c_master_send(client, buf, 5);
	}

	static const struct of_device_id of_omnia_leds_match[] = {
	{ .compatible = "cznic,turris-omnia-leds", },
	{},
	};
	MODULE_DEVICE_TABLE(of, of_omnia_leds_match);

	static const struct i2c_device_id omnia_id[] = {
	{ "omnia" },
	{ }
	};
	MODULE_DEVICE_TABLE(i2c, omnia_id);

	static struct i2c_driver omnia_leds_driver = {
	.probe = omnia_leds_probe,
	.remove = omnia_leds_remove,
	.id_table = omnia_id,
	.driver = {
	.name = "leds-turris-omnia",
	.of_match_table = of_omnia_leds_match,
	.dev_groups = omnia_led_controller_groups,
	},
	};

	module_i2c_driver(omnia_leds_driver);

	MODULE_AUTHOR("Marek Behun <kabel@kernel.org>");
	MODULE_DESCRIPTION("CZ.NIC's Turris Omnia LEDs");
	MODULE_LICENSE("GPL v2");