leds: driver for National Semiconductor LP5521 chip

This patchset provides support for LP5521 and LP5523 LED driver chips from
National Semicondutor.  Both drivers supports programmable engines and
naturally LED class features.

Documentation is provided as a part of the patchset.  I created "leds"
subdirectory under Documentation.  Perhaps the rest of the leds*
documentation should be moved there.

Datasheets are freely available at National Semiconductor www pages.

This patch:

LP5521 chip is three channel led driver with programmable engines.  Driver
provides support for that chip for direct access via led class or via
programmable engines.
Signed-off-by: Samu Onkalo <samu.p.onkalo@nokia.com>
Cc: Richard Purdie <rpurdie@rpsys.net>
Cc: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/leds/leds-lp5521.c

+/*
+ * LP5521 LED chip driver.
+ *
+ * Copyright (C) 2010 Nokia Corporation
+ *
+ * Contact: Samu Onkalo <samu.p.onkalo@nokia.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
+ * 02110-1301 USA
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/i2c.h>
+#include <linux/mutex.h>
+#include <linux/gpio.h>
+#include <linux/interrupt.h>
+#include <linux/delay.h>
+#include <linux/ctype.h>
+#include <linux/spinlock.h>
+#include <linux/wait.h>
+#include <linux/leds.h>
+#include <linux/leds-lp5521.h>
+#include <linux/workqueue.h>
+#include <linux/slab.h>
+
+#define LP5521_PROGRAM_LENGTH		32	/* in bytes */
+
+#define LP5521_MAX_LEDS			3	/* Maximum number of LEDs */
+#define LP5521_MAX_ENGINES		3	/* Maximum number of engines */
+
+#define LP5521_ENG_MASK_BASE		0x30	/* 00110000 */
+#define LP5521_ENG_STATUS_MASK		0x07	/* 00000111 */
+
+#define LP5521_CMD_LOAD			0x15	/* 00010101 */
+#define LP5521_CMD_RUN			0x2a	/* 00101010 */
+#define LP5521_CMD_DIRECT		0x3f	/* 00111111 */
+#define LP5521_CMD_DISABLED		0x00	/* 00000000 */
+
+/* Registers */
+#define LP5521_REG_ENABLE		0x00
+#define LP5521_REG_OP_MODE		0x01
+#define LP5521_REG_R_PWM		0x02
+#define LP5521_REG_G_PWM		0x03
+#define LP5521_REG_B_PWM		0x04
+#define LP5521_REG_R_CURRENT		0x05
+#define LP5521_REG_G_CURRENT		0x06
+#define LP5521_REG_B_CURRENT		0x07
+#define LP5521_REG_CONFIG		0x08
+#define LP5521_REG_R_CHANNEL_PC		0x09
+#define LP5521_REG_G_CHANNEL_PC		0x0A
+#define LP5521_REG_B_CHANNEL_PC		0x0B
+#define LP5521_REG_STATUS		0x0C
+#define LP5521_REG_RESET		0x0D
+#define LP5521_REG_GPO			0x0E
+#define LP5521_REG_R_PROG_MEM		0x10
+#define LP5521_REG_G_PROG_MEM		0x30
+#define LP5521_REG_B_PROG_MEM		0x50
+
+#define LP5521_PROG_MEM_BASE		LP5521_REG_R_PROG_MEM
+#define LP5521_PROG_MEM_SIZE		0x20
+
+/* Base register to set LED current */
+#define LP5521_REG_LED_CURRENT_BASE	LP5521_REG_R_CURRENT
+
+/* Base register to set the brightness */
+#define LP5521_REG_LED_PWM_BASE		LP5521_REG_R_PWM
+
+/* Bits in ENABLE register */
+#define LP5521_MASTER_ENABLE		0x40	/* Chip master enable */
+#define LP5521_LOGARITHMIC_PWM		0x80	/* Logarithmic PWM adjustment */
+#define LP5521_EXEC_RUN			0x2A
+
+/* Bits in CONFIG register */
+#define LP5521_PWM_HF			0x40	/* PWM: 0 = 256Hz, 1 = 558Hz */
+#define LP5521_PWRSAVE_EN		0x20	/* 1 = Power save mode */
+#define LP5521_CP_MODE_OFF		0	/* Charge pump (CP) off */
+#define LP5521_CP_MODE_BYPASS		8	/* CP forced to bypass mode */
+#define LP5521_CP_MODE_1X5		0x10	/* CP forced to 1.5x mode */
+#define LP5521_CP_MODE_AUTO		0x18	/* Automatic mode selection */
+#define LP5521_R_TO_BATT		4	/* R out: 0 = CP, 1 = Vbat */
+#define LP5521_CLK_SRC_EXT		0	/* Ext-clk source (CLK_32K) */
+#define LP5521_CLK_INT			1	/* Internal clock */
+#define LP5521_CLK_AUTO			2	/* Automatic clock selection */
+
+/* Status */
+#define LP5521_EXT_CLK_USED		0x08
+
+struct lp5521_engine {
+	const struct attribute_group *attributes;
+	int		id;
+	u8		mode;
+	u8		prog_page;
+	u8		engine_mask;
+};
+
+struct lp5521_led {
+	int			id;
+	u8			chan_nr;
+	u8			led_current;
+	u8			max_current;
+	struct led_classdev	cdev;
+	struct work_struct	brightness_work;
+	u8			brightness;
+};
+
+struct lp5521_chip {
+	struct lp5521_platform_data *pdata;
+	struct mutex		lock; /* Serialize control */
+	struct i2c_client	*client;
+	struct lp5521_engine	engines[LP5521_MAX_ENGINES];
+	struct lp5521_led	leds[LP5521_MAX_LEDS];
+	u8			num_channels;
+	u8			num_leds;
+};
+
+#define cdev_to_led(c)		container_of(c, struct lp5521_led, cdev)
+#define engine_to_lp5521(eng)	container_of((eng), struct lp5521_chip, \
+						engines[(eng)->id - 1])
+#define led_to_lp5521(led)	container_of((led), struct lp5521_chip, \
+						leds[(led)->id])
+
+static void lp5521_led_brightness_work(struct work_struct *work);
+
+static inline int lp5521_write(struct i2c_client *client, u8 reg, u8 value)
+{
+	return i2c_smbus_write_byte_data(client, reg, value);
+}
+
+static int lp5521_read(struct i2c_client *client, u8 reg, u8 *buf)
+{
+	s32 ret;
+
+	ret = i2c_smbus_read_byte_data(client, reg);
+	if (ret < 0)
+		return -EIO;
+
+	*buf = ret;
+	return 0;
+}
+
+static int lp5521_set_engine_mode(struct lp5521_engine *engine, u8 mode)
+{
+	struct lp5521_chip *chip = engine_to_lp5521(engine);
+	struct i2c_client *client = chip->client;
+	int ret;
+	u8 engine_state;
+
+	/* Only transition between RUN and DIRECT mode are handled here */
+	if (mode == LP5521_CMD_LOAD)
+		return 0;
+
+	if (mode == LP5521_CMD_DISABLED)
+		mode = LP5521_CMD_DIRECT;
+
+	ret = lp5521_read(client, LP5521_REG_OP_MODE, &engine_state);
+
+	/* set mode only for this engine */
+	engine_state &= ~(engine->engine_mask);
+	mode &= engine->engine_mask;
+	engine_state |= mode;
+	ret |= lp5521_write(client, LP5521_REG_OP_MODE, engine_state);
+
+	return ret;
+}
+
+static int lp5521_load_program(struct lp5521_engine *eng, const u8 *pattern)
+{
+	struct lp5521_chip *chip = engine_to_lp5521(eng);
+	struct i2c_client *client = chip->client;
+	int ret;
+	int addr;
+	u8 mode;
+
+	/* move current engine to direct mode and remember the state */
+	ret = lp5521_set_engine_mode(eng, LP5521_CMD_DIRECT);
+	usleep_range(1000, 10000);
+	ret |= lp5521_read(client, LP5521_REG_OP_MODE, &mode);
+
+	/* For loading, all the engines to load mode */
+	lp5521_write(client, LP5521_REG_OP_MODE, LP5521_CMD_DIRECT);
+	usleep_range(1000, 10000);
+	lp5521_write(client, LP5521_REG_OP_MODE, LP5521_CMD_LOAD);
+	usleep_range(1000, 10000);
+
+	addr = LP5521_PROG_MEM_BASE + eng->prog_page * LP5521_PROG_MEM_SIZE;
+	i2c_smbus_write_i2c_block_data(client,
+				addr,
+				LP5521_PROG_MEM_SIZE,
+				pattern);
+
+	ret |= lp5521_write(client, LP5521_REG_OP_MODE, mode);
+	return ret;
+}
+
+static int lp5521_set_led_current(struct lp5521_chip *chip, int led, u8 curr)
+{
+	return lp5521_write(chip->client,
+		    LP5521_REG_LED_CURRENT_BASE + chip->leds[led].chan_nr,
+		    curr);
+}
+
+static void lp5521_init_engine(struct lp5521_chip *chip,
+			const struct attribute_group *attr_group)
+{
+	int i;
+	for (i = 0; i < ARRAY_SIZE(chip->engines); i++) {
+		chip->engines[i].id = i + 1;
+		chip->engines[i].engine_mask = LP5521_ENG_MASK_BASE >> (i * 2);
+		chip->engines[i].prog_page = i;
+		chip->engines[i].attributes = &attr_group[i];
+	}
+}
+
+static int lp5521_configure(struct i2c_client *client,
+			const struct attribute_group *attr_group)
+{
+	struct lp5521_chip *chip = i2c_get_clientdata(client);
+	int ret;
+
+	lp5521_init_engine(chip, attr_group);
+
+	lp5521_write(client, LP5521_REG_RESET, 0xff);
+
+	usleep_range(10000, 20000);
+
+	/* Set all PWMs to direct control mode */
+	ret = lp5521_write(client, LP5521_REG_OP_MODE, 0x3F);
+
+	/* Enable auto-powersave, set charge pump to auto, red to battery */
+	ret |= lp5521_write(client, LP5521_REG_CONFIG,
+		LP5521_PWRSAVE_EN | LP5521_CP_MODE_AUTO | LP5521_R_TO_BATT);
+
+	/* Initialize all channels PWM to zero -> leds off */
+	ret |= lp5521_write(client, LP5521_REG_R_PWM, 0);
+	ret |= lp5521_write(client, LP5521_REG_G_PWM, 0);
+	ret |= lp5521_write(client, LP5521_REG_B_PWM, 0);
+
+	/* Set engines are set to run state when OP_MODE enables engines */
+	ret |= lp5521_write(client, LP5521_REG_ENABLE,
+			LP5521_MASTER_ENABLE | LP5521_LOGARITHMIC_PWM |
+			LP5521_EXEC_RUN);
+	/* enable takes 500us */
+	usleep_range(500, 20000);
+
+	return ret;
+}
+
+static int lp5521_run_selftest(struct lp5521_chip *chip, char *buf)
+{
+	int ret;
+	u8 status;
+
+	ret = lp5521_read(chip->client, LP5521_REG_STATUS, &status);
+	if (ret < 0)
+		return ret;
+
+	/* Check that ext clock is really in use if requested */
+	if (chip->pdata && chip->pdata->clock_mode == LP5521_CLOCK_EXT)
+		if  ((status & LP5521_EXT_CLK_USED) == 0)
+			return -EIO;
+	return 0;
+}
+
+static void lp5521_set_brightness(struct led_classdev *cdev,
+			     enum led_brightness brightness)
+{
+	struct lp5521_led *led = cdev_to_led(cdev);
+	led->brightness = (u8)brightness;
+	schedule_work(&led->brightness_work);
+}
+
+static void lp5521_led_brightness_work(struct work_struct *work)
+{
+	struct lp5521_led *led = container_of(work,
+					      struct lp5521_led,
+					      brightness_work);
+	struct lp5521_chip *chip = led_to_lp5521(led);
+	struct i2c_client *client = chip->client;
+
+	mutex_lock(&chip->lock);
+	lp5521_write(client, LP5521_REG_LED_PWM_BASE + led->chan_nr,
+		led->brightness);
+	mutex_unlock(&chip->lock);
+}
+
+/* Detect the chip by setting its ENABLE register and reading it back. */
+static int lp5521_detect(struct i2c_client *client)
+{
+	int ret;
+	u8 buf;
+
+	ret = lp5521_write(client, LP5521_REG_ENABLE,
+			LP5521_MASTER_ENABLE | LP5521_LOGARITHMIC_PWM);
+	if (ret)
+		return ret;
+	usleep_range(1000, 10000);
+	ret = lp5521_read(client, LP5521_REG_ENABLE, &buf);
+	if (ret)
+		return ret;
+	if (buf != (LP5521_MASTER_ENABLE | LP5521_LOGARITHMIC_PWM))
+		return -ENODEV;
+
+	return 0;
+}
+
+/* Set engine mode and create appropriate sysfs attributes, if required. */
+static int lp5521_set_mode(struct lp5521_engine *engine, u8 mode)
+{
+	struct lp5521_chip *chip = engine_to_lp5521(engine);
+	struct i2c_client *client = chip->client;
+	struct device *dev = &client->dev;
+	int ret = 0;
+
+	/* if in that mode already do nothing, except for run */
+	if (mode == engine->mode && mode != LP5521_CMD_RUN)
+		return 0;
+
+	if (mode == LP5521_CMD_RUN) {
+		ret = lp5521_set_engine_mode(engine, LP5521_CMD_RUN);
+	} else if (mode == LP5521_CMD_LOAD) {
+		lp5521_set_engine_mode(engine, LP5521_CMD_DISABLED);
+		lp5521_set_engine_mode(engine, LP5521_CMD_LOAD);
+
+		ret = sysfs_create_group(&dev->kobj, engine->attributes);
+		if (ret)
+			return ret;
+	} else if (mode == LP5521_CMD_DISABLED) {
+		lp5521_set_engine_mode(engine, LP5521_CMD_DISABLED);
+	}
+
+	/* remove load attribute from sysfs if not in load mode */
+	if (engine->mode == LP5521_CMD_LOAD && mode != LP5521_CMD_LOAD)
+		sysfs_remove_group(&dev->kobj, engine->attributes);
+
+	engine->mode = mode;
+
+	return ret;
+}
+
+static int lp5521_do_store_load(struct lp5521_engine *engine,
+				const char *buf, size_t len)
+{
+	struct lp5521_chip *chip = engine_to_lp5521(engine);
+	struct i2c_client *client = chip->client;
+	int  ret, nrchars, offset = 0, i = 0;
+	char c[3];
+	unsigned cmd;
+	u8 pattern[LP5521_PROGRAM_LENGTH] = {0};
+
+	while ((offset < len - 1) && (i < LP5521_PROGRAM_LENGTH)) {
+		/* separate sscanfs because length is working only for %s */
+		ret = sscanf(buf + offset, "%2s%n ", c, &nrchars);
+		ret = sscanf(c, "%2x", &cmd);
+		if (ret != 1)
+			goto fail;
+		pattern[i] = (u8)cmd;
+
+		offset += nrchars;
+		i++;
+	}
+
+	/* Each instruction is 16bit long. Check that length is even */
+	if (i % 2)
+		goto fail;
+
+	mutex_lock(&chip->lock);
+	ret = lp5521_load_program(engine, pattern);
+	mutex_unlock(&chip->lock);
+
+	if (ret) {
+		dev_err(&client->dev, "failed loading pattern\n");
+		return ret;
+	}
+
+	return len;
+fail:
+	dev_err(&client->dev, "wrong pattern format\n");
+	return -EINVAL;
+}
+
+static ssize_t store_engine_load(struct device *dev,
+				     struct device_attribute *attr,
+				     const char *buf, size_t len, int nr)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct lp5521_chip *chip = i2c_get_clientdata(client);
+	return lp5521_do_store_load(&chip->engines[nr - 1], buf, len);
+}
+
+#define store_load(nr)							\
+static ssize_t store_engine##nr##_load(struct device *dev,		\
+				     struct device_attribute *attr,	\
+				     const char *buf, size_t len)	\
+{									\
+	return store_engine_load(dev, attr, buf, len, nr);		\
+}
+store_load(1)
+store_load(2)
+store_load(3)
+
+static ssize_t show_engine_mode(struct device *dev,
+				struct device_attribute *attr,
+				char *buf, int nr)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct lp5521_chip *chip = i2c_get_clientdata(client);
+	switch (chip->engines[nr - 1].mode) {
+	case LP5521_CMD_RUN:
+		return sprintf(buf, "run\n");
+	case LP5521_CMD_LOAD:
+		return sprintf(buf, "load\n");
+	case LP5521_CMD_DISABLED:
+		return sprintf(buf, "disabled\n");
+	default:
+		return sprintf(buf, "disabled\n");
+	}
+}
+
+#define show_mode(nr)							\
+static ssize_t show_engine##nr##_mode(struct device *dev,		\
+				    struct device_attribute *attr,	\
+				    char *buf)				\
+{									\
+	return show_engine_mode(dev, attr, buf, nr);			\
+}
+show_mode(1)
+show_mode(2)
+show_mode(3)
+
+static ssize_t store_engine_mode(struct device *dev,
+				 struct device_attribute *attr,
+				 const char *buf, size_t len, int nr)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct lp5521_chip *chip = i2c_get_clientdata(client);
+	struct lp5521_engine *engine = &chip->engines[nr - 1];
+	mutex_lock(&chip->lock);
+
+	if (!strncmp(buf, "run", 3))
+		lp5521_set_mode(engine, LP5521_CMD_RUN);
+	else if (!strncmp(buf, "load", 4))
+		lp5521_set_mode(engine, LP5521_CMD_LOAD);
+	else if (!strncmp(buf, "disabled", 8))
+		lp5521_set_mode(engine, LP5521_CMD_DISABLED);
+
+	mutex_unlock(&chip->lock);
+	return len;
+}
+
+#define store_mode(nr)							\
+static ssize_t store_engine##nr##_mode(struct device *dev,		\
+				     struct device_attribute *attr,	\
+				     const char *buf, size_t len)	\
+{									\
+	return store_engine_mode(dev, attr, buf, len, nr);		\
+}
+store_mode(1)
+store_mode(2)
+store_mode(3)
+
+static ssize_t show_max_current(struct device *dev,
+			    struct device_attribute *attr,
+			    char *buf)
+{
+	struct led_classdev *led_cdev = dev_get_drvdata(dev);
+	struct lp5521_led *led = cdev_to_led(led_cdev);
+
+	return sprintf(buf, "%d\n", led->max_current);
+}
+
+static ssize_t show_current(struct device *dev,
+			    struct device_attribute *attr,
+			    char *buf)
+{
+	struct led_classdev *led_cdev = dev_get_drvdata(dev);
+	struct lp5521_led *led = cdev_to_led(led_cdev);
+
+	return sprintf(buf, "%d\n", led->led_current);
+}
+
+static ssize_t store_current(struct device *dev,
+			     struct device_attribute *attr,
+			     const char *buf, size_t len)
+{
+	struct led_classdev *led_cdev = dev_get_drvdata(dev);
+	struct lp5521_led *led = cdev_to_led(led_cdev);
+	struct lp5521_chip *chip = led_to_lp5521(led);
+	ssize_t ret;
+	unsigned long curr;
+
+	if (strict_strtoul(buf, 0, &curr))
+		return -EINVAL;
+
+	if (curr > led->max_current)
+		return -EINVAL;
+
+	mutex_lock(&chip->lock);
+	ret = lp5521_set_led_current(chip, led->id, curr);
+	mutex_unlock(&chip->lock);
+
+	if (ret < 0)
+		return ret;
+
+	led->led_current = (u8)curr;
+
+	return len;
+}
+
+static ssize_t lp5521_selftest(struct device *dev,
+			       struct device_attribute *attr,
+			       char *buf)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct lp5521_chip *chip = i2c_get_clientdata(client);
+	int ret;
+
+	mutex_lock(&chip->lock);
+	ret = lp5521_run_selftest(chip, buf);
+	mutex_unlock(&chip->lock);
+	return sprintf(buf, "%s\n", ret ? "FAIL" : "OK");
+}
+
+/* led class device attributes */
+static DEVICE_ATTR(led_current, S_IRUGO | S_IWUGO, show_current, store_current);
+static DEVICE_ATTR(max_current, S_IRUGO , show_max_current, NULL);
+
+static struct attribute *lp5521_led_attributes[] = {
+	&dev_attr_led_current.attr,
+	&dev_attr_max_current.attr,
+	NULL,
+};
+
+static struct attribute_group lp5521_led_attribute_group = {
+	.attrs = lp5521_led_attributes
+};
+
+/* device attributes */
+static DEVICE_ATTR(engine1_mode, S_IRUGO | S_IWUGO,
+		   show_engine1_mode, store_engine1_mode);
+static DEVICE_ATTR(engine2_mode, S_IRUGO | S_IWUGO,
+		   show_engine2_mode, store_engine2_mode);
+static DEVICE_ATTR(engine3_mode, S_IRUGO | S_IWUGO,
+		   show_engine3_mode, store_engine3_mode);
+static DEVICE_ATTR(engine1_load, S_IWUGO, NULL, store_engine1_load);
+static DEVICE_ATTR(engine2_load, S_IWUGO, NULL, store_engine2_load);
+static DEVICE_ATTR(engine3_load, S_IWUGO, NULL, store_engine3_load);
+static DEVICE_ATTR(selftest, S_IRUGO, lp5521_selftest, NULL);
+
+static struct attribute *lp5521_attributes[] = {
+	&dev_attr_engine1_mode.attr,
+	&dev_attr_engine2_mode.attr,
+	&dev_attr_engine3_mode.attr,
+	&dev_attr_selftest.attr,
+	NULL
+};
+
+static struct attribute *lp5521_engine1_attributes[] = {
+	&dev_attr_engine1_load.attr,
+	NULL
+};
+
+static struct attribute *lp5521_engine2_attributes[] = {
+	&dev_attr_engine2_load.attr,
+	NULL
+};
+
+static struct attribute *lp5521_engine3_attributes[] = {
+	&dev_attr_engine3_load.attr,
+	NULL
+};
+
+static const struct attribute_group lp5521_group = {
+	.attrs = lp5521_attributes,
+};
+
+static const struct attribute_group lp5521_engine_group[] = {
+	{.attrs = lp5521_engine1_attributes },
+	{.attrs = lp5521_engine2_attributes },
+	{.attrs = lp5521_engine3_attributes },
+};
+
+static int lp5521_register_sysfs(struct i2c_client *client)
+{
+	struct device *dev = &client->dev;
+	return sysfs_create_group(&dev->kobj, &lp5521_group);
+}
+
+static void lp5521_unregister_sysfs(struct i2c_client *client)
+{
+	struct lp5521_chip *chip = i2c_get_clientdata(client);
+	struct device *dev = &client->dev;
+	int i;
+
+	sysfs_remove_group(&dev->kobj, &lp5521_group);
+
+	for (i = 0; i <  ARRAY_SIZE(chip->engines); i++) {
+		if (chip->engines[i].mode == LP5521_CMD_LOAD)
+			sysfs_remove_group(&dev->kobj,
+					chip->engines[i].attributes);
+	}
+
+	for (i = 0; i < chip->num_leds; i++)
+		sysfs_remove_group(&chip->leds[i].cdev.dev->kobj,
+				&lp5521_led_attribute_group);
+}
+
+static int __init lp5521_init_led(struct lp5521_led *led,
+				struct i2c_client *client,
+				int chan, struct lp5521_platform_data *pdata)
+{
+	struct device *dev = &client->dev;
+	char name[32];
+	int res;
+
+	if (chan >= LP5521_MAX_LEDS)
+		return -EINVAL;
+
+	if (pdata->led_config[chan].led_current == 0)
+		return 0;
+
+	led->led_current = pdata->led_config[chan].led_current;
+	led->max_current = pdata->led_config[chan].max_current;
+	led->chan_nr = pdata->led_config[chan].chan_nr;
+
+	if (led->chan_nr >= LP5521_MAX_LEDS) {
+		dev_err(dev, "Use channel numbers between 0 and %d\n",
+			LP5521_MAX_LEDS - 1);
+		return -EINVAL;
+	}
+
+	snprintf(name, sizeof(name), "%s:channel%d", client->name, chan);
+	led->cdev.brightness_set = lp5521_set_brightness;
+	led->cdev.name = name;
+	res = led_classdev_register(dev, &led->cdev);
+	if (res < 0) {
+		dev_err(dev, "couldn't register led on channel %d\n", chan);
+		return res;
+	}
+
+	res = sysfs_create_group(&led->cdev.dev->kobj,
+			&lp5521_led_attribute_group);
+	if (res < 0) {
+		dev_err(dev, "couldn't register current attribute\n");
+		led_classdev_unregister(&led->cdev);
+		return res;
+	}
+	return 0;
+}
+
+static int lp5521_probe(struct i2c_client *client,
+			const struct i2c_device_id *id)
+{
+	struct lp5521_chip		*chip;
+	struct lp5521_platform_data	*pdata;
+	int ret, i, led;
+
+	chip = kzalloc(sizeof(*chip), GFP_KERNEL);
+	if (!chip)
+		return -ENOMEM;
+
+	i2c_set_clientdata(client, chip);
+	chip->client = client;
+
+	pdata = client->dev.platform_data;
+
+	if (!pdata) {
+		dev_err(&client->dev, "no platform data\n");
+		ret = -EINVAL;
+		goto fail1;
+	}
+
+	mutex_init(&chip->lock);
+
+	chip->pdata   = pdata;
+
+	if (pdata->setup_resources) {
+		ret = pdata->setup_resources();
+		if (ret < 0)
+			goto fail1;
+	}
+
+	if (pdata->enable) {
+		pdata->enable(0);
+		usleep_range(1000, 10000);
+		pdata->enable(1);
+		usleep_range(1000, 10000); /* Spec says min 500us */
+	}
+
+	ret = lp5521_detect(client);
+
+	if (ret) {
+		dev_err(&client->dev, "Chip not found\n");
+		goto fail2;
+	}
+
+	dev_info(&client->dev, "%s programmable led chip found\n", id->name);
+
+	ret = lp5521_configure(client, lp5521_engine_group);
+	if (ret < 0) {
+		dev_err(&client->dev, "error configuring chip\n");
+		goto fail2;
+	}
+
+	/* Initialize leds */
+	chip->num_channels = pdata->num_channels;
+	chip->num_leds = 0;
+	led = 0;
+	for (i = 0; i < pdata->num_channels; i++) {
+		/* Do not initialize channels that are not connected */
+		if (pdata->led_config[i].led_current == 0)
+			continue;
+
+		ret = lp5521_init_led(&chip->leds[led], client, i, pdata);
+		if (ret) {
+			dev_err(&client->dev, "error initializing leds\n");
+			goto fail3;
+		}
+		chip->num_leds++;
+
+		chip->leds[led].id = led;
+		/* Set initial LED current */
+		lp5521_set_led_current(chip, led,
+				chip->leds[led].led_current);
+
+		INIT_WORK(&(chip->leds[led].brightness_work),
+			lp5521_led_brightness_work);
+
+		led++;
+	}
+
+	ret = lp5521_register_sysfs(client);
+	if (ret) {
+		dev_err(&client->dev, "registering sysfs failed\n");
+		goto fail3;
+	}
+	return ret;
+fail3:
+	for (i = 0; i < chip->num_leds; i++) {
+		led_classdev_unregister(&chip->leds[i].cdev);
+		cancel_work_sync(&chip->leds[i].brightness_work);
+	}
+fail2:
+	if (pdata->enable)
+		pdata->enable(0);
+	if (pdata->release_resources)
+		pdata->release_resources();
+fail1:
+	kfree(chip);
+	return ret;
+}
+
+static int lp5521_remove(struct i2c_client *client)
+{
+	struct lp5521_chip *chip = i2c_get_clientdata(client);
+	int i;
+
+	lp5521_unregister_sysfs(client);
+
+	for (i = 0; i < chip->num_leds; i++) {
+		led_classdev_unregister(&chip->leds[i].cdev);
+		cancel_work_sync(&chip->leds[i].brightness_work);
+	}
+
+	if (chip->pdata->enable)
+		chip->pdata->enable(0);
+	if (chip->pdata->release_resources)
+		chip->pdata->release_resources();
+	kfree(chip);
+	return 0;
+}
+
+static const struct i2c_device_id lp5521_id[] = {
+	{ "lp5521", 0 }, /* Three channel chip */
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, lp5521_id);
+
+static struct i2c_driver lp5521_driver = {
+	.driver = {
+		.name	= "lp5521",
+	},
+	.probe		= lp5521_probe,
+	.remove		= lp5521_remove,
+	.id_table	= lp5521_id,
+};
+
+static int __init lp5521_init(void)
+{
+	int ret;
+
+	ret = i2c_add_driver(&lp5521_driver);
+
+	if (ret < 0)
+		printk(KERN_ALERT "Adding lp5521 driver failed\n");
+
+	return ret;
+}
+
+static void __exit lp5521_exit(void)
+{
+	i2c_del_driver(&lp5521_driver);
+}
+
+module_init(lp5521_init);
+module_exit(lp5521_exit);
+
+MODULE_AUTHOR("Mathias Nyman, Yuri Zaporozhets, Samu Onkalo");
+MODULE_DESCRIPTION("LP5521 LED engine");
+MODULE_LICENSE("GPL v2");

include/linux/leds-lp5521.h

+/*
+ * LP5521 LED chip driver.
+ *
+ * Copyright (C) 2010 Nokia Corporation
+ *
+ * Contact: Samu Onkalo <samu.p.onkalo@nokia.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
+ * 02110-1301 USA
+ */
+
+#ifndef __LINUX_LP5521_H
+#define __LINUX_LP5521_H
+
+/* See Documentation/leds/leds-lp5521.txt */
+
+struct lp5521_led_config {
+	u8		chan_nr;
+	u8		led_current; /* mA x10, 0 if led is not connected */
+	u8		max_current;
+};
+
+#define LP5521_CLOCK_AUTO	0
+#define LP5521_CLOCK_INT	1
+#define LP5521_CLOCK_EXT	2
+
+struct lp5521_platform_data {
+	struct lp5521_led_config *led_config;
+	u8	num_channels;
+	u8	clock_mode;
+	int	(*setup_resources)(void);
+	void	(*release_resources)(void);
+	void	(*enable)(bool state);
+};
+
+#endif /* __LINUX_LP5521_H */