linux/drivers/leds/leds-blinkm.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  leds-blinkm.c
 *  (c) Jan-Simon Möller (dl9pf@gmx.de)
 *  (c) Joseph Strauss (jstrauss@mailbox.org)
 */

#include <linux/module.h>
#include <linux/slab.h>
#include <linux/jiffies.h>
#include <linux/i2c.h>
#include <linux/err.h>
#include <linux/mutex.h>
#include <linux/sysfs.h>
#include <linux/printk.h>
#include <linux/pm_runtime.h>
#include <linux/leds.h>
#include <linux/delay.h>
#include <linux/led-class-multicolor.h>
#include <linux/kconfig.h>

#define NUM_LEDS 3

/* Addresses to scan - BlinkM is on 0x09 by default*/
static const unsigned short normal_i2c[] = { 0x09, I2C_CLIENT_END };

static int blinkm_transfer_hw(struct i2c_client *client, int cmd);
static int blinkm_test_run(struct i2c_client *client);

/* Contains structs for both the color-separated sysfs classes, and the new multicolor class */
struct blinkm_led {
	struct i2c_client *i2c_client;
	union {
		/* used when multicolor support is disabled */
		struct led_classdev led_cdev;
		struct led_classdev_mc mcled_cdev;
	} cdev;
	int id;
};

#define led_cdev_to_blmled(c)			container_of(c, struct blinkm_led, cdev.led_cdev)
#define mcled_cdev_to_led(c)			container_of(c, struct blinkm_led, cdev.mcled_cdev)

struct blinkm_data {
	struct i2c_client *i2c_client;
	struct mutex update_lock;
	/* used for led class interface */
	struct blinkm_led blinkm_leds[NUM_LEDS];
	/* used for "blinkm" sysfs interface */
	u8 red;			/* color red */
	u8 green;		/* color green */
	u8 blue;		/* color blue */
	/* next values to use for transfer */
	u8 next_red;			/* color red */
	u8 next_green;		/* color green */
	u8 next_blue;		/* color blue */
	/* internal use */
	u8 args[7];		/* set of args for transmission */
	u8 i2c_addr;		/* i2c addr */
	u8 fw_ver;		/* firmware version */
	/* used, but not from userspace */
	u8 hue;			/* HSB  hue */
	u8 saturation;		/* HSB  saturation */
	u8 brightness;		/* HSB  brightness */
	u8 next_hue;			/* HSB  hue */
	u8 next_saturation;		/* HSB  saturation */
	u8 next_brightness;		/* HSB  brightness */
	/* currently unused / todo */
	u8 fade_speed;		/* fade speed     1 - 255 */
	s8 time_adjust;		/* time adjust -128 - 127 */
	u8 fade:1;		/* fade on = 1, off = 0 */
	u8 rand:1;		/* rand fade mode on = 1 */
	u8 script_id;		/* script ID */
	u8 script_repeats;	/* repeats of script */
	u8 script_startline;	/* line to start */
};

/* Colors */
#define RED   0
#define GREEN 1
#define BLUE  2

/* mapping command names to cmd chars - see datasheet */
#define BLM_GO_RGB            0
#define BLM_FADE_RGB          1
#define BLM_FADE_HSB          2
#define BLM_FADE_RAND_RGB     3
#define BLM_FADE_RAND_HSB     4
#define BLM_PLAY_SCRIPT       5
#define BLM_STOP_SCRIPT       6
#define BLM_SET_FADE_SPEED    7
#define BLM_SET_TIME_ADJ      8
#define BLM_GET_CUR_RGB       9
#define BLM_WRITE_SCRIPT_LINE 10
#define BLM_READ_SCRIPT_LINE  11
#define BLM_SET_SCRIPT_LR     12	/* Length & Repeats */
#define BLM_SET_ADDR          13
#define BLM_GET_ADDR          14
#define BLM_GET_FW_VER        15
#define BLM_SET_STARTUP_PARAM 16

/* BlinkM Commands
 *  as extracted out of the datasheet:
 *
 *  cmdchar = command (ascii)
 *  cmdbyte = command in hex
 *  nr_args = number of arguments (to send)
 *  nr_ret  = number of return values (to read)
 *  dir = direction (0 = read, 1 = write, 2 = both)
 *
 */
static const struct {
	char cmdchar;
	u8 cmdbyte;
	u8 nr_args;
	u8 nr_ret;
	u8 dir:2;
} blinkm_cmds[17] = {
  /* cmdchar, cmdbyte, nr_args, nr_ret,  dir */
	{ 'n', 0x6e, 3, 0, 1},
	{ 'c', 0x63, 3, 0, 1},
	{ 'h', 0x68, 3, 0, 1},
	{ 'C', 0x43, 3, 0, 1},
	{ 'H', 0x48, 3, 0, 1},
	{ 'p', 0x70, 3, 0, 1},
	{ 'o', 0x6f, 0, 0, 1},
	{ 'f', 0x66, 1, 0, 1},
	{ 't', 0x74, 1, 0, 1},
	{ 'g', 0x67, 0, 3, 0},
	{ 'W', 0x57, 7, 0, 1},
	{ 'R', 0x52, 2, 5, 2},
	{ 'L', 0x4c, 3, 0, 1},
	{ 'A', 0x41, 4, 0, 1},
	{ 'a', 0x61, 0, 1, 0},
	{ 'Z', 0x5a, 0, 1, 0},
	{ 'B', 0x42, 5, 0, 1},
};

static ssize_t show_color_common(struct device *dev, char *buf, int color)
{
	struct i2c_client *client;
	struct blinkm_data *data;
	int ret;

	client = to_i2c_client(dev);
	data = i2c_get_clientdata(client);

	ret = blinkm_transfer_hw(client, BLM_GET_CUR_RGB);
	if (ret < 0)
		return ret;
	switch (color) {
	case RED:
		return sysfs_emit(buf, "%02X\n", data->red);
	case GREEN:
		return sysfs_emit(buf, "%02X\n", data->green);
	case BLUE:
		return sysfs_emit(buf, "%02X\n", data->blue);
	default:
		return -EINVAL;
	}
	return -EINVAL;
}

static int store_color_common(struct device *dev, const char *buf, int color)
{
	struct i2c_client *client;
	struct blinkm_data *data;
	int ret;
	u8 value;

	client = to_i2c_client(dev);
	data = i2c_get_clientdata(client);

	ret = kstrtou8(buf, 10, &value);
	if (ret < 0) {
		dev_err(dev, "BlinkM: value too large!\n");
		return ret;
	}

	switch (color) {
	case RED:
		data->next_red = value;
		break;
	case GREEN:
		data->next_green = value;
		break;
	case BLUE:
		data->next_blue = value;
		break;
	default:
		return -EINVAL;
	}

	dev_dbg(dev, "next_red = %d, next_green = %d, next_blue = %d\n",
			data->next_red, data->next_green, data->next_blue);

	/* if mode ... */
	ret = blinkm_transfer_hw(client, BLM_GO_RGB);
	if (ret < 0) {
		dev_err(dev, "BlinkM: can't set RGB\n");
		return ret;
	}
	return 0;
}

static ssize_t red_show(struct device *dev, struct device_attribute *attr,
			char *buf)
{
	return show_color_common(dev, buf, RED);
}

static ssize_t red_store(struct device *dev, struct device_attribute *attr,
			 const char *buf, size_t count)
{
	int ret;

	ret = store_color_common(dev, buf, RED);
	if (ret < 0)
		return ret;
	return count;
}

static DEVICE_ATTR_RW(red);

static ssize_t green_show(struct device *dev, struct device_attribute *attr,
			  char *buf)
{
	return show_color_common(dev, buf, GREEN);
}

static ssize_t green_store(struct device *dev, struct device_attribute *attr,
			   const char *buf, size_t count)
{

	int ret;

	ret = store_color_common(dev, buf, GREEN);
	if (ret < 0)
		return ret;
	return count;
}

static DEVICE_ATTR_RW(green);

static ssize_t blue_show(struct device *dev, struct device_attribute *attr,
			 char *buf)
{
	return show_color_common(dev, buf, BLUE);
}

static ssize_t blue_store(struct device *dev, struct device_attribute *attr,
			  const char *buf, size_t count)
{
	int ret;

	ret = store_color_common(dev, buf, BLUE);
	if (ret < 0)
		return ret;
	return count;
}

static DEVICE_ATTR_RW(blue);

static ssize_t test_show(struct device *dev, struct device_attribute *attr,
			 char *buf)
{
	return sysfs_emit(buf,
			 "#Write into test to start test sequence!#\n");
}

static ssize_t test_store(struct device *dev, struct device_attribute *attr,
			  const char *buf, size_t count)
{

	struct i2c_client *client;
	int ret;
	client = to_i2c_client(dev);

	/*test */
	ret = blinkm_test_run(client);
	if (ret < 0)
		return ret;

	return count;
}

static DEVICE_ATTR_RW(test);

/* TODO: HSB, fade, timeadj, script ... */

static struct attribute *blinkm_attrs[] = {
	&dev_attr_red.attr,
	&dev_attr_green.attr,
	&dev_attr_blue.attr,
	&dev_attr_test.attr,
	NULL,
};

static const struct attribute_group blinkm_group = {
	.name = "blinkm",
	.attrs = blinkm_attrs,
};

static int blinkm_write(struct i2c_client *client, int cmd, u8 *arg)
{
	int result;
	int i;
	int arglen = blinkm_cmds[cmd].nr_args;
	/* write out cmd to blinkm - always / default step */
	result = i2c_smbus_write_byte(client, blinkm_cmds[cmd].cmdbyte);
	if (result < 0)
		return result;
	/* no args to write out */
	if (arglen == 0)
		return 0;

	for (i = 0; i < arglen; i++) {
		/* repeat for arglen */
		result = i2c_smbus_write_byte(client, arg[i]);
		if (result < 0)
			return result;
	}
	return 0;
}

static int blinkm_read(struct i2c_client *client, int cmd, u8 *arg)
{
	int result;
	int i;
	int retlen = blinkm_cmds[cmd].nr_ret;
	for (i = 0; i < retlen; i++) {
		/* repeat for retlen */
		result = i2c_smbus_read_byte(client);
		if (result < 0)
			return result;
		arg[i] = result;
	}

	return 0;
}

static int blinkm_transfer_hw(struct i2c_client *client, int cmd)
{
	/* the protocol is simple but non-standard:
	 * e.g.  cmd 'g' (= 0x67) for "get device address"
	 * - which defaults to 0x09 - would be the sequence:
	 *   a) write 0x67 to the device (byte write)
	 *   b) read the value (0x09) back right after (byte read)
	 *
	 * Watch out for "unfinished" sequences (i.e. not enough reads
	 * or writes after a command. It will make the blinkM misbehave.
	 * Sequence is key here.
	 */

	/* args / return are in private data struct */
	struct blinkm_data *data = i2c_get_clientdata(client);

	/* We start hardware transfers which are not to be
	 * mixed with other commands. Aquire a lock now. */
	if (mutex_lock_interruptible(&data->update_lock) < 0)
		return -EAGAIN;

	/* switch cmd - usually write before reads */
	switch (cmd) {
	case BLM_FADE_RAND_RGB:
	case BLM_GO_RGB:
	case BLM_FADE_RGB:
		data->args[0] = data->next_red;
		data->args[1] = data->next_green;
		data->args[2] = data->next_blue;
		blinkm_write(client, cmd, data->args);
		data->red = data->args[0];
		data->green = data->args[1];
		data->blue = data->args[2];
		break;
	case BLM_FADE_HSB:
	case BLM_FADE_RAND_HSB:
		data->args[0] = data->next_hue;
		data->args[1] = data->next_saturation;
		data->args[2] = data->next_brightness;
		blinkm_write(client, cmd, data->args);
		data->hue = data->next_hue;
		data->saturation = data->next_saturation;
		data->brightness = data->next_brightness;
		break;
	case BLM_PLAY_SCRIPT:
		data->args[0] = data->script_id;
		data->args[1] = data->script_repeats;
		data->args[2] = data->script_startline;
		blinkm_write(client, cmd, data->args);
		break;
	case BLM_STOP_SCRIPT:
		blinkm_write(client, cmd, NULL);
		break;
	case BLM_GET_CUR_RGB:
		data->args[0] = data->red;
		data->args[1] = data->green;
		data->args[2] = data->blue;
		blinkm_write(client, cmd, NULL);
		blinkm_read(client, cmd, data->args);
		data->red = data->args[0];
		data->green = data->args[1];
		data->blue = data->args[2];
		break;
	case BLM_GET_ADDR:
		data->args[0] = data->i2c_addr;
		blinkm_write(client, cmd, NULL);
		blinkm_read(client, cmd, data->args);
		data->i2c_addr = data->args[0];
		break;
	case BLM_SET_TIME_ADJ:
	case BLM_SET_FADE_SPEED:
	case BLM_READ_SCRIPT_LINE:
	case BLM_WRITE_SCRIPT_LINE:
	case BLM_SET_SCRIPT_LR:
	case BLM_SET_ADDR:
	case BLM_GET_FW_VER:
	case BLM_SET_STARTUP_PARAM:
		dev_err(&client->dev,
				"BlinkM: cmd %d not implemented yet.\n", cmd);
		break;
	default:
		dev_err(&client->dev, "BlinkM: unknown command %d\n", cmd);
		mutex_unlock(&data->update_lock);
		return -EINVAL;
	}			/* end switch(cmd) */

	/* transfers done, unlock */
	mutex_unlock(&data->update_lock);
	return 0;
}

static int blinkm_set_mc_brightness(struct led_classdev *led_cdev,
				 enum led_brightness value)
{
	struct led_classdev_mc *mcled_cdev = lcdev_to_mccdev(led_cdev);
	struct blinkm_led *led = mcled_cdev_to_led(mcled_cdev);
	struct blinkm_data *data = i2c_get_clientdata(led->i2c_client);

	led_mc_calc_color_components(mcled_cdev, value);

	data->next_red = (u8) mcled_cdev->subled_info[RED].brightness;
	data->next_green = (u8) mcled_cdev->subled_info[GREEN].brightness;
	data->next_blue = (u8) mcled_cdev->subled_info[BLUE].brightness;

	blinkm_transfer_hw(led->i2c_client, BLM_GO_RGB);

	return 0;
}

static int blinkm_led_common_set(struct led_classdev *led_cdev,
				 enum led_brightness value, int color)
{
	/* led_brightness is 0, 127 or 255 - we just use it here as-is */
	struct blinkm_led *led = led_cdev_to_blmled(led_cdev);
	struct blinkm_data *data = i2c_get_clientdata(led->i2c_client);

	switch (color) {
	case RED:
		/* bail out if there's no change */
		if (data->next_red == (u8) value)
			return 0;
		data->next_red = (u8) value;
		break;
	case GREEN:
		/* bail out if there's no change */
		if (data->next_green == (u8) value)
			return 0;
		data->next_green = (u8) value;
		break;
	case BLUE:
		/* bail out if there's no change */
		if (data->next_blue == (u8) value)
			return 0;
		data->next_blue = (u8) value;
		break;

	default:
		dev_err(&led->i2c_client->dev, "BlinkM: unknown color.\n");
		return -EINVAL;
	}

	blinkm_transfer_hw(led->i2c_client, BLM_GO_RGB);
	dev_dbg(&led->i2c_client->dev,
			"# DONE # next_red = %d, next_green = %d,"
			" next_blue = %d\n",
			data->next_red, data->next_green,
			data->next_blue);
	return 0;
}

static int blinkm_led_red_set(struct led_classdev *led_cdev,
			       enum led_brightness value)
{
	return blinkm_led_common_set(led_cdev, value, RED);
}

static int blinkm_led_green_set(struct led_classdev *led_cdev,
				 enum led_brightness value)
{
	return blinkm_led_common_set(led_cdev, value, GREEN);
}

static int blinkm_led_blue_set(struct led_classdev *led_cdev,
				enum led_brightness value)
{
	return blinkm_led_common_set(led_cdev, value, BLUE);
}

static void blinkm_init_hw(struct i2c_client *client)
{
	blinkm_transfer_hw(client, BLM_STOP_SCRIPT);
	blinkm_transfer_hw(client, BLM_GO_RGB);
}

static int blinkm_test_run(struct i2c_client *client)
{
	int ret;
	struct blinkm_data *data = i2c_get_clientdata(client);

	data->next_red = 0x01;
	data->next_green = 0x05;
	data->next_blue = 0x10;
	ret = blinkm_transfer_hw(client, BLM_GO_RGB);
	if (ret < 0)
		return ret;
	msleep(2000);

	data->next_red = 0x25;
	data->next_green = 0x10;
	data->next_blue = 0x31;
	ret = blinkm_transfer_hw(client, BLM_FADE_RGB);
	if (ret < 0)
		return ret;
	msleep(2000);

	data->next_hue = 0x50;
	data->next_saturation = 0x10;
	data->next_brightness = 0x20;
	ret = blinkm_transfer_hw(client, BLM_FADE_HSB);
	if (ret < 0)
		return ret;
	msleep(2000);

	return 0;
}

/* Return 0 if detection is successful, -ENODEV otherwise */
static int blinkm_detect(struct i2c_client *client, struct i2c_board_info *info)
{
	struct i2c_adapter *adapter = client->adapter;
	int ret;
	int count = 99;
	u8 tmpargs[7];

	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA
				     | I2C_FUNC_SMBUS_WORD_DATA
				     | I2C_FUNC_SMBUS_WRITE_BYTE))
		return -ENODEV;

	/* Now, we do the remaining detection. Simple for now. */
	/* We might need more guards to protect other i2c slaves */

	/* make sure the blinkM is balanced (read/writes) */
	while (count > 0) {
		ret = blinkm_write(client, BLM_GET_ADDR, NULL);
		if (ret)
			return ret;
		usleep_range(5000, 10000);
		ret = blinkm_read(client, BLM_GET_ADDR, tmpargs);
		if (ret)
			return ret;
		usleep_range(5000, 10000);
		if (tmpargs[0] == 0x09)
			count = 0;
		count--;
	}

	/* Step 1: Read BlinkM address back  -  cmd_char 'a' */
	ret = blinkm_write(client, BLM_GET_ADDR, NULL);
	if (ret < 0)
		return ret;
	usleep_range(20000, 30000);	/* allow a small delay */
	ret = blinkm_read(client, BLM_GET_ADDR, tmpargs);
	if (ret < 0)
		return ret;

	if (tmpargs[0] != 0x09) {
		dev_err(&client->dev, "enodev DEV ADDR = 0x%02X\n", tmpargs[0]);
		return -ENODEV;
	}

	strscpy(info->type, "blinkm", I2C_NAME_SIZE);
	return 0;
}

static int register_separate_colors(struct i2c_client *client, struct blinkm_data *data)
{
	/* 3 separate classes for red, green, and blue respectively */
	struct blinkm_led *leds[NUM_LEDS];
	int err;
	char blinkm_led_name[28];
	/* Register red, green, and blue sysfs classes */
	for (int i = 0; i < NUM_LEDS; i++) {
		/* RED = 0, GREEN = 1, BLUE = 2 */
		leds[i] = &data->blinkm_leds[i];
		leds[i]->i2c_client = client;
		leds[i]->id = i;
		leds[i]->cdev.led_cdev.max_brightness = 255;
		leds[i]->cdev.led_cdev.flags = LED_CORE_SUSPENDRESUME;
		switch (i) {
		case RED:
			scnprintf(blinkm_led_name, sizeof(blinkm_led_name),
					 "blinkm-%d-%d-red",
					 client->adapter->nr,
					 client->addr);
			leds[i]->cdev.led_cdev.name = blinkm_led_name;
			leds[i]->cdev.led_cdev.brightness_set_blocking =
							blinkm_led_red_set;
			err = led_classdev_register(&client->dev,
							&leds[i]->cdev.led_cdev);
			if (err < 0) {
				dev_err(&client->dev,
					"couldn't register LED %s\n",
					leds[i]->cdev.led_cdev.name);
				goto failred;
			}
			break;
		case GREEN:
			scnprintf(blinkm_led_name, sizeof(blinkm_led_name),
					 "blinkm-%d-%d-green",
					 client->adapter->nr,
					 client->addr);
			leds[i]->cdev.led_cdev.name = blinkm_led_name;
			leds[i]->cdev.led_cdev.brightness_set_blocking =
							blinkm_led_green_set;
			err = led_classdev_register(&client->dev,
						&leds[i]->cdev.led_cdev);
			if (err < 0) {
				dev_err(&client->dev,
					"couldn't register LED %s\n",
					leds[i]->cdev.led_cdev.name);
				goto failgreen;
			}
			break;
		case BLUE:
			scnprintf(blinkm_led_name, sizeof(blinkm_led_name),
					 "blinkm-%d-%d-blue",
					 client->adapter->nr,
					 client->addr);
			leds[i]->cdev.led_cdev.name = blinkm_led_name;
			leds[i]->cdev.led_cdev.brightness_set_blocking =
							blinkm_led_blue_set;
			err = led_classdev_register(&client->dev,
							&leds[i]->cdev.led_cdev);
			if (err < 0) {
				dev_err(&client->dev,
					"couldn't register LED %s\n",
					leds[i]->cdev.led_cdev.name);
				goto failblue;
			}
			break;
		default:
			break;
		}		/* end switch */
	}			/* end for */
	return 0;

failblue:
	led_classdev_unregister(&leds[GREEN]->cdev.led_cdev);
failgreen:
	led_classdev_unregister(&leds[RED]->cdev.led_cdev);
failred:
	sysfs_remove_group(&client->dev.kobj, &blinkm_group);

	return err;
}

static int register_multicolor(struct i2c_client *client, struct blinkm_data *data)
{
	struct blinkm_led *mc_led;
	struct mc_subled *mc_led_info;
	char blinkm_led_name[28];
	int err;

	/* Register multicolor sysfs class */
	/* The first element of leds is used for multicolor facilities */
	mc_led = &data->blinkm_leds[RED];
	mc_led->i2c_client = client;

	mc_led_info = devm_kcalloc(&client->dev, NUM_LEDS, sizeof(*mc_led_info),
					GFP_KERNEL);
	if (!mc_led_info)
		return -ENOMEM;

	mc_led_info[RED].color_index = LED_COLOR_ID_RED;
	mc_led_info[GREEN].color_index = LED_COLOR_ID_GREEN;
	mc_led_info[BLUE].color_index = LED_COLOR_ID_BLUE;

	mc_led->cdev.mcled_cdev.subled_info = mc_led_info;
	mc_led->cdev.mcled_cdev.num_colors = NUM_LEDS;
	mc_led->cdev.mcled_cdev.led_cdev.brightness = 255;
	mc_led->cdev.mcled_cdev.led_cdev.max_brightness = 255;
	mc_led->cdev.mcled_cdev.led_cdev.flags = LED_CORE_SUSPENDRESUME;

	scnprintf(blinkm_led_name, sizeof(blinkm_led_name),
		 "blinkm-%d-%d:rgb:indicator",
		 client->adapter->nr,
		 client->addr);
	mc_led->cdev.mcled_cdev.led_cdev.name = blinkm_led_name;
	mc_led->cdev.mcled_cdev.led_cdev.brightness_set_blocking = blinkm_set_mc_brightness;

	err = led_classdev_multicolor_register(&client->dev, &mc_led->cdev.mcled_cdev);
	if (err < 0) {
		dev_err(&client->dev, "couldn't register LED %s\n",
				mc_led->cdev.led_cdev.name);
		sysfs_remove_group(&client->dev.kobj, &blinkm_group);
	}
	return 0;
}

static int blinkm_probe(struct i2c_client *client)
{
	struct blinkm_data *data;
	int err;

	data = devm_kzalloc(&client->dev,
			sizeof(struct blinkm_data), GFP_KERNEL);
	if (!data)
		return -ENOMEM;

	data->i2c_addr = 0x08;
	/* i2c addr  - use fake addr of 0x08 initially (real is 0x09) */
	data->fw_ver = 0xfe;
	/* firmware version - use fake until we read real value
	 * (currently broken - BlinkM confused!)
	 */
	data->script_id = 0x01;
	data->i2c_client = client;

	i2c_set_clientdata(client, data);
	mutex_init(&data->update_lock);

	/* Register sysfs hooks */
	err = sysfs_create_group(&client->dev.kobj, &blinkm_group);
	if (err < 0) {
		dev_err(&client->dev, "couldn't register sysfs group\n");
		return err;
	}

	if (!IS_ENABLED(CONFIG_LEDS_BLINKM_MULTICOLOR)) {
		err = register_separate_colors(client, data);
		if (err < 0)
			return err;
	} else {
		err = register_multicolor(client, data);
		if (err < 0)
			return err;
	}

	blinkm_init_hw(client);

	return 0;
}

static void blinkm_remove(struct i2c_client *client)
{
	struct blinkm_data *data = i2c_get_clientdata(client);
	int ret = 0;
	int i;

	/* make sure no workqueue entries are pending */
	for (i = 0; i < NUM_LEDS; i++)
		led_classdev_unregister(&data->blinkm_leds[i].cdev.led_cdev);

	/* reset rgb */
	data->next_red = 0x00;
	data->next_green = 0x00;
	data->next_blue = 0x00;
	ret = blinkm_transfer_hw(client, BLM_FADE_RGB);
	if (ret < 0)
		dev_err(&client->dev, "Failure in blinkm_remove ignored. Continuing.\n");

	/* reset hsb */
	data->next_hue = 0x00;
	data->next_saturation = 0x00;
	data->next_brightness = 0x00;
	ret = blinkm_transfer_hw(client, BLM_FADE_HSB);
	if (ret < 0)
		dev_err(&client->dev, "Failure in blinkm_remove ignored. Continuing.\n");

	/* red fade to off */
	data->next_red = 0xff;
	ret = blinkm_transfer_hw(client, BLM_GO_RGB);
	if (ret < 0)
		dev_err(&client->dev, "Failure in blinkm_remove ignored. Continuing.\n");

	/* off */
	data->next_red = 0x00;
	ret = blinkm_transfer_hw(client, BLM_FADE_RGB);
	if (ret < 0)
		dev_err(&client->dev, "Failure in blinkm_remove ignored. Continuing.\n");

	sysfs_remove_group(&client->dev.kobj, &blinkm_group);
}

static const struct i2c_device_id blinkm_id[] = {
	{ "blinkm" },
	{}
};

MODULE_DEVICE_TABLE(i2c, blinkm_id);

  /* This is the driver that will be inserted */
static struct i2c_driver blinkm_driver = {
	.class = I2C_CLASS_HWMON,
	.driver = {
		   .name = "blinkm",
		   },
	.probe = blinkm_probe,
	.remove = blinkm_remove,
	.id_table = blinkm_id,
	.detect = blinkm_detect,
	.address_list = normal_i2c,
};

module_i2c_driver(blinkm_driver);

MODULE_AUTHOR("Jan-Simon Moeller <dl9pf@gmx.de>");
MODULE_AUTHOR("Joseph Strauss <jstrauss@mailbox.org>");
MODULE_DESCRIPTION("BlinkM RGB LED driver");
MODULE_LICENSE("GPL");