Message-ID: <20100922001403.GI7494@trinity.fluff.org>
Date:	Wed, 22 Sep 2010 01:14:03 +0100
From:	Ben Dooks <ben-i2c@...ff.org>
To:	Samu Onkalo <samu.p.onkalo@...ia.com>
Cc:	rpurdie@...ux.intel.com, linux-i2c@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/4] leds: driver for National Semiconductor LP5521 chip

On Thu, Sep 16, 2010 at 01:12:23PM +0300, Samu Onkalo wrote:
> 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@...ia.com>
> ---
>  drivers/leds/leds-lp5521.c  |  820 +++++++++++++++++++++++++++++++++++++++++++
>  include/linux/leds-lp5521.h |   46 +++
>  2 files changed, 866 insertions(+), 0 deletions(-)
>  create mode 100644 drivers/leds/leds-lp5521.c
>  create mode 100644 include/linux/leds-lp5521.h
> 
> diff --git a/drivers/leds/leds-lp5521.c b/drivers/leds/leds-lp5521.c
> new file mode 100644
> index 0000000..f57adb0
> --- /dev/null
> +++ b/drivers/leds/leds-lp5521.c
> @@ -0,0 +1,820 @@
> +/*
> + * LP5521 LED chip driver.
> + *
> + * Copyright (C) 2010 Nokia Corporation
> + *
> + * Contact: Samu Onkalo <samu.p.onkalo@...ia.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 < LP5521_MAX_ENGINES; i++) {

you could use ARRAY_SIZE(chip->engines) ?

> +		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 ssize_t 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)
> +		goto fail;
> +
> +	/* 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)
> +			goto fail;
> +
> +	return sprintf(buf, "OK\n");
> +fail:
> +	return sprintf(buf, "FAIL\n");
> +}

why not return an error code here?

> +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++;
> +	}
> +
> +	/* Pattern commands are always two bytes long */
> +	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);
> +	ssize_t ret = 0;
> +
> +	mutex_lock(&chip->lock);
> +	ret = lp5521_run_selftest(chip, buf);
> +	mutex_unlock(&chip->lock);
> +	return ret;
> +}
> +
> +/* 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 < LP5521_MAX_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;
> +
> +	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;
> +
> +		chip->num_leds++;
> +		ret = lp5521_init_led(&chip->leds[led], client, i, pdata);
> +		if (ret) {
> +			dev_err(&client->dev, "error initializing leds\n");
> +			goto fail3;
> +		}
> +
> +		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");
> diff --git a/include/linux/leds-lp5521.h b/include/linux/leds-lp5521.h
> new file mode 100644
> index 0000000..2d3aca2
> --- /dev/null
> +++ b/include/linux/leds-lp5521.h
> @@ -0,0 +1,46 @@
> +/*
> + * LP5521 LED chip driver.
> + *
> + * Copyright (C) 2010 Nokia Corporation
> + *
> + * Contact: Samu Onkalo <samu.p.onkalo@...ia.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
> +
> +struct lp5521_led_config {
> +	u8		chan_nr;
> +	u8		led_current; /* mA x10, 0 if led is not connected */
> +	u8		max_current;
> +};

documentation would be useful. kerneldoc fo preference.

> +#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 */
> +
> -- 
> 1.6.0.4
> 
> --
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-- 
-- 
Ben

Q:      What's a light-year?
A:      One-third less calories than a regular year.

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