leds: LED driver for National Semiconductor LP3944 Funlight Chip

LEDs driver for National Semiconductor LP3944 Funlight Chip
http://www.national.com/pf/LP/LP3944.html



This helper chip can drive up to 8 leds, with two programmable DIM
modes; it could even be used as a gpio expander but this driver assumes
it is used as a led controller.

The DIM modes are used to set _blink_ patterns for leds, the pattern is
specified supplying two parameters:
  - period: from 0s to 1.6s
  - duty cycle: percentage of the period the led is on, from 0 to 100

LP3944 can be found on Motorola A910 smartphone, where it drives the rgb
leds, the camera flash light and the displays backlights.

Signed-off-by: Antonio Ospite <ospite@studenti.unina.it>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>

Documentation/leds-lp3944.txt

+Kernel driver lp3944
+====================
+
+  * National Semiconductor LP3944 Fun-light Chip
+    Prefix: 'lp3944'
+    Addresses scanned: None (see the Notes section below)
+    Datasheet: Publicly available at the National Semiconductor website
+               http://www.national.com/pf/LP/LP3944.html
+
+Authors:
+        Antonio Ospite <ospite@studenti.unina.it>
+
+
+Description
+-----------
+The LP3944 is a helper chip that can drive up to 8 leds, with two programmable
+DIM modes; it could even be used as a gpio expander but this driver assumes it
+is used as a led controller.
+
+The DIM modes are used to set _blink_ patterns for leds, the pattern is
+specified supplying two parameters:
+  - period: from 0s to 1.6s
+  - duty cycle: percentage of the period the led is on, from 0 to 100
+
+Setting a led in DIM0 or DIM1 mode makes it blink according to the pattern.
+See the datasheet for details.
+
+LP3944 can be found on Motorola A910 smartphone, where it drives the rgb
+leds, the camera flash light and the lcds power.
+
+
+Notes
+-----
+The chip is used mainly in embedded contexts, so this driver expects it is
+registered using the i2c_board_info mechanism.
+
+To register the chip at address 0x60 on adapter 0, set the platform data
+according to include/linux/leds-lp3944.h, set the i2c board info:
+
+	static struct i2c_board_info __initdata a910_i2c_board_info[] = {
+		{
+			I2C_BOARD_INFO("lp3944", 0x60),
+			.platform_data = &a910_lp3944_leds,
+		},
+	};
+
+and register it in the platform init function
+
+	i2c_register_board_info(0, a910_i2c_board_info,
+			ARRAY_SIZE(a910_i2c_board_info));

drivers/leds/Kconfig

@@ -146,6 +146,17 @@ config LEDS_GPIO_OF
 	  of_platform devices.  For instance, LEDs which are listed in a "dts"
 	  file.
 
+config LEDS_LP3944
+	tristate "LED Support for N.S. LP3944 (Fun Light) I2C chip"
+	depends on LEDS_CLASS && I2C
+	help
+    This option enables support for LEDs connected to the National
+    Semiconductor LP3944 Lighting Management Unit (LMU) also known as
+    Fun Light Chip.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called leds-lp3944.
+
 config LEDS_CLEVO_MAIL
 	tristate "Mail LED on Clevo notebook"
 	depends on LEDS_CLASS && X86 && SERIO_I8042 && DMI

drivers/leds/Makefile

@@ -20,6 +20,7 @@ obj-$(CONFIG_LEDS_COBALT_RAQ)		+= leds-cobalt-raq.o
 obj-$(CONFIG_LEDS_SUNFIRE)		+= leds-sunfire.o
 obj-$(CONFIG_LEDS_PCA9532)		+= leds-pca9532.o
 obj-$(CONFIG_LEDS_GPIO)			+= leds-gpio.o
+obj-$(CONFIG_LEDS_LP3944)		+= leds-lp3944.o
 obj-$(CONFIG_LEDS_CLEVO_MAIL)		+= leds-clevo-mail.o
 obj-$(CONFIG_LEDS_HP6XX)		+= leds-hp6xx.o
 obj-$(CONFIG_LEDS_FSG)			+= leds-fsg.o

drivers/leds/leds-lp3944.c

+/*
+ * leds-lp3944.c - driver for National Semiconductor LP3944 Funlight Chip
+ *
+ * Copyright (C) 2009 Antonio Ospite <ospite@studenti.unina.it>
+ *
+ * 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.
+ *
+ */
+
+/*
+ * I2C driver for National Semiconductor LP3944 Funlight Chip
+ * http://www.national.com/pf/LP/LP3944.html
+ *
+ * This helper chip can drive up to 8 leds, with two programmable DIM modes;
+ * it could even be used as a gpio expander but this driver assumes it is used
+ * as a led controller.
+ *
+ * The DIM modes are used to set _blink_ patterns for leds, the pattern is
+ * specified supplying two parameters:
+ *   - period: from 0s to 1.6s
+ *   - duty cycle: percentage of the period the led is on, from 0 to 100
+ *
+ * LP3944 can be found on Motorola A910 smartphone, where it drives the rgb
+ * leds, the camera flash light and the displays backlights.
+ */
+
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/leds.h>
+#include <linux/mutex.h>
+#include <linux/workqueue.h>
+#include <linux/leds-lp3944.h>
+
+/* Read Only Registers */
+#define LP3944_REG_INPUT1     0x00 /* LEDs 0-7 InputRegister (Read Only) */
+#define LP3944_REG_REGISTER1  0x01 /* None (Read Only) */
+
+#define LP3944_REG_PSC0       0x02 /* Frequency Prescaler 0 (R/W) */
+#define LP3944_REG_PWM0       0x03 /* PWM Register 0 (R/W) */
+#define LP3944_REG_PSC1       0x04 /* Frequency Prescaler 1 (R/W) */
+#define LP3944_REG_PWM1       0x05 /* PWM Register 1 (R/W) */
+#define LP3944_REG_LS0        0x06 /* LEDs 0-3 Selector (R/W) */
+#define LP3944_REG_LS1        0x07 /* LEDs 4-7 Selector (R/W) */
+
+/* These registers are not used to control leds in LP3944, they can store
+ * arbitrary values which the chip will ignore.
+ */
+#define LP3944_REG_REGISTER8  0x08
+#define LP3944_REG_REGISTER9  0x09
+
+#define LP3944_DIM0 0
+#define LP3944_DIM1 1
+
+/* period in ms */
+#define LP3944_PERIOD_MIN 0
+#define LP3944_PERIOD_MAX 1600
+
+/* duty cycle is a percentage */
+#define LP3944_DUTY_CYCLE_MIN 0
+#define LP3944_DUTY_CYCLE_MAX 100
+
+#define ldev_to_led(c)       container_of(c, struct lp3944_led_data, ldev)
+
+/* Saved data */
+struct lp3944_led_data {
+	u8 id;
+	enum lp3944_type type;
+	enum lp3944_status status;
+	struct led_classdev ldev;
+	struct i2c_client *client;
+	struct work_struct work;
+};
+
+struct lp3944_data {
+	struct mutex lock;
+	struct i2c_client *client;
+	struct lp3944_led_data leds[LP3944_LEDS_MAX];
+};
+
+static int lp3944_reg_read(struct i2c_client *client, u8 reg, u8 *value)
+{
+	int tmp;
+
+	tmp = i2c_smbus_read_byte_data(client, reg);
+	if (tmp < 0)
+		return -EINVAL;
+
+	*value = tmp;
+
+	return 0;
+}
+
+static int lp3944_reg_write(struct i2c_client *client, u8 reg, u8 value)
+{
+	return i2c_smbus_write_byte_data(client, reg, value);
+}
+
+/**
+ * Set the period for DIM status
+ *
+ * @client: the i2c client
+ * @dim: either LP3944_DIM0 or LP3944_DIM1
+ * @period: period of a blink, that is a on/off cycle, expressed in ms.
+ */
+static int lp3944_dim_set_period(struct i2c_client *client, u8 dim, u16 period)
+{
+	u8 psc_reg;
+	u8 psc_value;
+	int err;
+
+	if (dim == LP3944_DIM0)
+		psc_reg = LP3944_REG_PSC0;
+	else if (dim == LP3944_DIM1)
+		psc_reg = LP3944_REG_PSC1;
+	else
+		return -EINVAL;
+
+	/* Convert period to Prescaler value */
+	if (period > LP3944_PERIOD_MAX)
+		return -EINVAL;
+
+	psc_value = (period * 255) / LP3944_PERIOD_MAX;
+
+	err = lp3944_reg_write(client, psc_reg, psc_value);
+
+	return err;
+}
+
+/**
+ * Set the duty cycle for DIM status
+ *
+ * @client: the i2c client
+ * @dim: either LP3944_DIM0 or LP3944_DIM1
+ * @duty_cycle: percentage of a period during which a led is ON
+ */
+static int lp3944_dim_set_dutycycle(struct i2c_client *client, u8 dim,
+				    u8 duty_cycle)
+{
+	u8 pwm_reg;
+	u8 pwm_value;
+	int err;
+
+	if (dim == LP3944_DIM0)
+		pwm_reg = LP3944_REG_PWM0;
+	else if (dim == LP3944_DIM1)
+		pwm_reg = LP3944_REG_PWM1;
+	else
+		return -EINVAL;
+
+	/* Convert duty cycle to PWM value */
+	if (duty_cycle > LP3944_DUTY_CYCLE_MAX)
+		return -EINVAL;
+
+	pwm_value = (duty_cycle * 255) / LP3944_DUTY_CYCLE_MAX;
+
+	err = lp3944_reg_write(client, pwm_reg, pwm_value);
+
+	return err;
+}
+
+/**
+ * Set the led status
+ *
+ * @led: a lp3944_led_data structure
+ * @status: one of LP3944_LED_STATUS_OFF
+ *                 LP3944_LED_STATUS_ON
+ *                 LP3944_LED_STATUS_DIM0
+ *                 LP3944_LED_STATUS_DIM1
+ */
+static int lp3944_led_set(struct lp3944_led_data *led, u8 status)
+{
+	struct lp3944_data *data = i2c_get_clientdata(led->client);
+	u8 id = led->id;
+	u8 reg;
+	u8 val = 0;
+	int err;
+
+	dev_dbg(&led->client->dev, "%s: %s, status before normalization:%d\n",
+		__func__, led->ldev.name, status);
+
+	switch (id) {
+	case LP3944_LED0:
+	case LP3944_LED1:
+	case LP3944_LED2:
+	case LP3944_LED3:
+		reg = LP3944_REG_LS0;
+		break;
+	case LP3944_LED4:
+	case LP3944_LED5:
+	case LP3944_LED6:
+	case LP3944_LED7:
+		id -= LP3944_LED4;
+		reg = LP3944_REG_LS1;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	if (status > LP3944_LED_STATUS_DIM1)
+		return -EINVAL;
+
+	/* invert only 0 and 1, leave unchanged the other values,
+	 * remember we are abusing status to set blink patterns
+	 */
+	if (led->type == LP3944_LED_TYPE_LED_INVERTED && status < 2)
+		status = 1 - status;
+
+	mutex_lock(&data->lock);
+	lp3944_reg_read(led->client, reg, &val);
+
+	val &= ~(LP3944_LED_STATUS_MASK << (id << 1));
+	val |= (status << (id << 1));
+
+	dev_dbg(&led->client->dev, "%s: %s, reg:%d id:%d status:%d val:%#x\n",
+		__func__, led->ldev.name, reg, id, status, val);
+
+	/* set led status */
+	err = lp3944_reg_write(led->client, reg, val);
+	mutex_unlock(&data->lock);
+
+	return err;
+}
+
+static int lp3944_led_set_blink(struct led_classdev *led_cdev,
+				unsigned long *delay_on,
+				unsigned long *delay_off)
+{
+	struct lp3944_led_data *led = ldev_to_led(led_cdev);
+	u16 period;
+	u8 duty_cycle;
+	int err;
+
+	/* units are in ms */
+	if (*delay_on + *delay_off > LP3944_PERIOD_MAX)
+		return -EINVAL;
+
+	if (*delay_on == 0 && *delay_off == 0) {
+		/* Special case: the leds subsystem requires a default user
+		 * friendly blink pattern for the LED.  Let's blink the led
+		 * slowly (1Hz).
+		 */
+		*delay_on = 500;
+		*delay_off = 500;
+	}
+
+	period = (*delay_on) + (*delay_off);
+
+	/* duty_cycle is the percentage of period during which the led is ON */
+	duty_cycle = 100 * (*delay_on) / period;
+
+	/* invert duty cycle for inverted leds, this has the same effect of
+	 * swapping delay_on and delay_off
+	 */
+	if (led->type == LP3944_LED_TYPE_LED_INVERTED)
+		duty_cycle = 100 - duty_cycle;
+
+	/* NOTE: using always the first DIM mode, this means that all leds
+	 * will have the same blinking pattern.
+	 *
+	 * We could find a way later to have two leds blinking in hardware
+	 * with different patterns at the same time, falling back to software
+	 * control for the other ones.
+	 */
+	err = lp3944_dim_set_period(led->client, LP3944_DIM0, period);
+	if (err)
+		return err;
+
+	err = lp3944_dim_set_dutycycle(led->client, LP3944_DIM0, duty_cycle);
+	if (err)
+		return err;
+
+	dev_dbg(&led->client->dev, "%s: OK hardware accelerated blink!\n",
+		__func__);
+
+	led->status = LP3944_LED_STATUS_DIM0;
+	schedule_work(&led->work);
+
+	return 0;
+}
+
+static void lp3944_led_set_brightness(struct led_classdev *led_cdev,
+				      enum led_brightness brightness)
+{
+	struct lp3944_led_data *led = ldev_to_led(led_cdev);
+
+	dev_dbg(&led->client->dev, "%s: %s, %d\n",
+		__func__, led_cdev->name, brightness);
+
+	led->status = brightness;
+	schedule_work(&led->work);
+}
+
+static void lp3944_led_work(struct work_struct *work)
+{
+	struct lp3944_led_data *led;
+
+	led = container_of(work, struct lp3944_led_data, work);
+	lp3944_led_set(led, led->status);
+}
+
+static int lp3944_configure(struct i2c_client *client,
+			    struct lp3944_data *data,
+			    struct lp3944_platform_data *pdata)
+{
+	int i, err = 0;
+
+	for (i = 0; i < pdata->leds_size; i++) {
+		struct lp3944_led *pled = &pdata->leds[i];
+		struct lp3944_led_data *led = &data->leds[i];
+		led->client = client;
+		led->id = i;
+
+		switch (pled->type) {
+
+		case LP3944_LED_TYPE_LED:
+		case LP3944_LED_TYPE_LED_INVERTED:
+			led->type = pled->type;
+			led->status = pled->status;
+			led->ldev.name = pled->name;
+			led->ldev.max_brightness = 1;
+			led->ldev.brightness_set = lp3944_led_set_brightness;
+			led->ldev.blink_set = lp3944_led_set_blink;
+			led->ldev.flags = LED_CORE_SUSPENDRESUME;
+
+			INIT_WORK(&led->work, lp3944_led_work);
+			err = led_classdev_register(&client->dev, &led->ldev);
+			if (err < 0) {
+				dev_err(&client->dev,
+					"couldn't register LED %s\n",
+					led->ldev.name);
+				goto exit;
+			}
+
+			/* to expose the default value to userspace */
+			led->ldev.brightness = led->status;
+
+			/* Set the default led status */
+			err = lp3944_led_set(led, led->status);
+			if (err < 0) {
+				dev_err(&client->dev,
+					"%s couldn't set STATUS %d\n",
+					led->ldev.name, led->status);
+				goto exit;
+			}
+			break;
+
+		case LP3944_LED_TYPE_NONE:
+		default:
+			break;
+
+		}
+	}
+	return 0;
+
+exit:
+	if (i > 0)
+		for (i = i - 1; i >= 0; i--)
+			switch (pdata->leds[i].type) {
+
+			case LP3944_LED_TYPE_LED:
+			case LP3944_LED_TYPE_LED_INVERTED:
+				led_classdev_unregister(&data->leds[i].ldev);
+				cancel_work_sync(&data->leds[i].work);
+				break;
+
+			case LP3944_LED_TYPE_NONE:
+			default:
+				break;
+			}
+
+	return err;
+}
+
+static int __devinit lp3944_probe(struct i2c_client *client,
+				  const struct i2c_device_id *id)
+{
+	struct lp3944_platform_data *lp3944_pdata = client->dev.platform_data;
+	struct lp3944_data *data;
+
+	if (lp3944_pdata == NULL) {
+		dev_err(&client->dev, "no platform data\n");
+		return -EINVAL;
+	}
+
+	/* Let's see whether this adapter can support what we need. */
+	if (!i2c_check_functionality(client->adapter,
+				I2C_FUNC_SMBUS_BYTE_DATA)) {
+		dev_err(&client->dev, "insufficient functionality!\n");
+		return -ENODEV;
+	}
+
+	data = kzalloc(sizeof(struct lp3944_data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->client = client;
+	i2c_set_clientdata(client, data);
+
+	mutex_init(&data->lock);
+
+	dev_info(&client->dev, "lp3944 enabled\n");
+
+	lp3944_configure(client, data, lp3944_pdata);
+	return 0;
+}
+
+static int __devexit lp3944_remove(struct i2c_client *client)
+{
+	struct lp3944_platform_data *pdata = client->dev.platform_data;
+	struct lp3944_data *data = i2c_get_clientdata(client);
+	int i;
+
+	for (i = 0; i < pdata->leds_size; i++)
+		switch (data->leds[i].type) {
+		case LP3944_LED_TYPE_LED:
+		case LP3944_LED_TYPE_LED_INVERTED:
+			led_classdev_unregister(&data->leds[i].ldev);
+			cancel_work_sync(&data->leds[i].work);
+			break;
+
+		case LP3944_LED_TYPE_NONE:
+		default:
+			break;
+		}
+
+	kfree(data);
+	i2c_set_clientdata(client, NULL);
+
+	return 0;
+}
+
+/* lp3944 i2c driver struct */
+static const struct i2c_device_id lp3944_id[] = {
+	{"lp3944", 0},
+	{}
+};
+
+MODULE_DEVICE_TABLE(i2c, lp3944_id);
+
+static struct i2c_driver lp3944_driver = {
+	.driver   = {
+		   .name = "lp3944",
+	},
+	.probe    = lp3944_probe,
+	.remove   = __devexit_p(lp3944_remove),
+	.id_table = lp3944_id,
+};
+
+static int __init lp3944_module_init(void)
+{
+	return i2c_add_driver(&lp3944_driver);
+}
+
+static void __exit lp3944_module_exit(void)
+{
+	i2c_del_driver(&lp3944_driver);
+}
+
+module_init(lp3944_module_init);
+module_exit(lp3944_module_exit);
+
+MODULE_AUTHOR("Antonio Ospite <ospite@studenti.unina.it>");
+MODULE_DESCRIPTION("LP3944 Fun Light Chip");
+MODULE_LICENSE("GPL");

include/linux/leds-lp3944.h

+/*
+ * leds-lp3944.h - platform data structure for lp3944 led controller
+ *
+ * Copyright (C) 2009 Antonio Ospite <ospite@studenti.unina.it>
+ *
+ * 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.
+ *
+ */
+
+#ifndef __LINUX_LEDS_LP3944_H
+#define __LINUX_LEDS_LP3944_H
+
+#include <linux/leds.h>
+#include <linux/workqueue.h>
+
+#define LP3944_LED0 0
+#define LP3944_LED1 1
+#define LP3944_LED2 2
+#define LP3944_LED3 3
+#define LP3944_LED4 4
+#define LP3944_LED5 5
+#define LP3944_LED6 6
+#define LP3944_LED7 7
+#define LP3944_LEDS_MAX 8
+
+#define LP3944_LED_STATUS_MASK	0x03
+enum lp3944_status {
+	LP3944_LED_STATUS_OFF  = 0x0,
+	LP3944_LED_STATUS_ON   = 0x1,
+	LP3944_LED_STATUS_DIM0 = 0x2,
+	LP3944_LED_STATUS_DIM1 = 0x3
+};
+
+enum lp3944_type {
+	LP3944_LED_TYPE_NONE,
+	LP3944_LED_TYPE_LED,
+	LP3944_LED_TYPE_LED_INVERTED,
+};
+
+struct lp3944_led {
+	char *name;
+	enum lp3944_type type;
+	enum lp3944_status status;
+};
+
+struct lp3944_platform_data {
+	struct lp3944_led leds[LP3944_LEDS_MAX];
+	u8 leds_size;
+};
+
+#endif /* __LINUX_LEDS_LP3944_H */