Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit a8dd18fe authored by Daniel Mack's avatar Daniel Mack Committed by Richard Purdie
Browse files

leds: Add driver for LT3593 controlled LEDs 



The LT3593 is a step-up DC/DC converter designed to drive up to ten
white LEDs in series. The current flow can be set with a control pin.

This driver controls any number of such devices connected on generic
GPIOs and exports the function as as platform_driver.

The gpio_led platform data struct definition is reused for this purpose.

Successfully tested on a PXA embedded board.

Signed-off-by: default avatarDaniel Mack <daniel@caiaq.de>
Signed-off-by: default avatarRichard Purdie <rpurdie@linux.intel.com>
parent 09a46db0

drivers/leds/Kconfig

+8 −0
Original line number Diff line number Diff line
@@ -245,6 +245,14 @@ config LEDS_INTEL_SS4200 
	  drive or power LEDs on the front panel.  Using this driver

	  can stop the front LED from blinking after startup.



config LEDS_LT3593

	tristate "LED driver for LT3593 controllers"

	depends on LEDS_CLASS && GENERIC_GPIO

	help

	  This option enables support for LEDs driven by a Linear Technology

	  LT3593 controller. This controller uses a special one-wire pulse

	  coding protocol to set the brightness.



comment "LED Triggers"



config LEDS_TRIGGERS

drivers/leds/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -30,6 +30,7 @@ obj-$(CONFIG_LEDS_WM831X_STATUS) += leds-wm831x-status.o 
obj-$(CONFIG_LEDS_WM8350)		+= leds-wm8350.o

obj-$(CONFIG_LEDS_PWM)			+= leds-pwm.o

obj-$(CONFIG_LEDS_INTEL_SS4200)		+= leds-ss4200.o

obj-$(CONFIG_LEDS_LT3593)		+= leds-lt3593.o



# LED SPI Drivers

obj-$(CONFIG_LEDS_DAC124S085)		+= leds-dac124s085.o

drivers/leds/leds-lt3593.c

0 → 100644
+217 −0
Original line number Diff line number Diff line 
/*

 * LEDs driver for LT3593 controllers

 *

 * See the datasheet at http://cds.linear.com/docs/Datasheet/3593f.pdf

 *

 * Copyright (c) 2009 Daniel Mack <daniel@caiaq.de>

 *

 * Based on leds-gpio.c,

 *

 *   Copyright (C) 2007 8D Technologies inc.

 *   Raphael Assenat <raph@8d.com>

 *   Copyright (C) 2008 Freescale Semiconductor, Inc.

 *

 * 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.

 */



#include <linux/kernel.h>

#include <linux/init.h>

#include <linux/platform_device.h>

#include <linux/leds.h>

#include <linux/workqueue.h>

#include <linux/delay.h>

#include <linux/gpio.h>



struct lt3593_led_data {

	struct led_classdev cdev;

	unsigned gpio;

	struct work_struct work;

	u8 new_level;

};



static void lt3593_led_work(struct work_struct *work)

{

	int pulses;

	struct lt3593_led_data *led_dat =

		container_of(work, struct lt3593_led_data, work);



	/*

	 * The LT3593 resets its internal current level register to the maximum

	 * level on the first falling edge on the control pin. Each following

	 * falling edge decreases the current level by 625uA. Up to 32 pulses

	 * can be sent, so the maximum power reduction is 20mA.

	 * After a timeout of 128us, the value is taken from the register and

	 * applied is to the output driver.

	 */



	if (led_dat->new_level == 0) {

		gpio_set_value_cansleep(led_dat->gpio, 0);

		return;

	}



	pulses = 32 - (led_dat->new_level * 32) / 255;



	if (pulses == 0) {

		gpio_set_value_cansleep(led_dat->gpio, 0);

		mdelay(1);

		gpio_set_value_cansleep(led_dat->gpio, 1);

		return;

	}



	gpio_set_value_cansleep(led_dat->gpio, 1);



	while (pulses--) {

		gpio_set_value_cansleep(led_dat->gpio, 0);

		udelay(1);

		gpio_set_value_cansleep(led_dat->gpio, 1);

		udelay(1);

	}

}



static void lt3593_led_set(struct led_classdev *led_cdev,

	enum led_brightness value)

{

	struct lt3593_led_data *led_dat =

		container_of(led_cdev, struct lt3593_led_data, cdev);



	led_dat->new_level = value;

	schedule_work(&led_dat->work);

}



static int __devinit create_lt3593_led(const struct gpio_led *template,

	struct lt3593_led_data *led_dat, struct device *parent)

{

	int ret, state;



	/* skip leds on GPIOs that aren't available */

	if (!gpio_is_valid(template->gpio)) {

		printk(KERN_INFO "%s: skipping unavailable LT3593 LED at gpio %d (%s)\n",

				KBUILD_MODNAME, template->gpio, template->name);

		return 0;

	}



	ret = gpio_request(template->gpio, template->name);

	if (ret < 0)

		return ret;



	led_dat->cdev.name = template->name;

	led_dat->cdev.default_trigger = template->default_trigger;

	led_dat->gpio = template->gpio;



	led_dat->cdev.brightness_set = lt3593_led_set;



	state = (template->default_state == LEDS_GPIO_DEFSTATE_ON);

	led_dat->cdev.brightness = state ? LED_FULL : LED_OFF;



	if (!template->retain_state_suspended)

		led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME;



	ret = gpio_direction_output(led_dat->gpio, state);

	if (ret < 0)

		goto err;



	INIT_WORK(&led_dat->work, lt3593_led_work);



	ret = led_classdev_register(parent, &led_dat->cdev);

	if (ret < 0)

		goto err;



	printk(KERN_INFO "%s: registered LT3593 LED '%s' at GPIO %d\n",

		KBUILD_MODNAME, template->name, template->gpio);



	return 0;



err:

	gpio_free(led_dat->gpio);

	return ret;

}



static void delete_lt3593_led(struct lt3593_led_data *led)

{

	if (!gpio_is_valid(led->gpio))

		return;



	led_classdev_unregister(&led->cdev);

	cancel_work_sync(&led->work);

	gpio_free(led->gpio);

}



static int __devinit lt3593_led_probe(struct platform_device *pdev)

{

	struct gpio_led_platform_data *pdata = pdev->dev.platform_data;

	struct lt3593_led_data *leds_data;

	int i, ret = 0;



	if (!pdata)

		return -EBUSY;



	leds_data = kzalloc(sizeof(struct lt3593_led_data) * pdata->num_leds,

				GFP_KERNEL);

	if (!leds_data)

		return -ENOMEM;



	for (i = 0; i < pdata->num_leds; i++) {

		ret = create_lt3593_led(&pdata->leds[i], &leds_data[i],

				      &pdev->dev);

		if (ret < 0)

			goto err;

	}



	platform_set_drvdata(pdev, leds_data);



	return 0;



err:

	for (i = i - 1; i >= 0; i--)

		delete_lt3593_led(&leds_data[i]);



	kfree(leds_data);



	return ret;

}



static int __devexit lt3593_led_remove(struct platform_device *pdev)

{

	int i;

	struct gpio_led_platform_data *pdata = pdev->dev.platform_data;

	struct lt3593_led_data *leds_data;



	leds_data = platform_get_drvdata(pdev);



	for (i = 0; i < pdata->num_leds; i++)

		delete_lt3593_led(&leds_data[i]);



	kfree(leds_data);



	return 0;

}



static struct platform_driver lt3593_led_driver = {

	.probe		= lt3593_led_probe,

	.remove		= __devexit_p(lt3593_led_remove),

	.driver		= {

		.name	= "leds-lt3593",

		.owner	= THIS_MODULE,

	},

};



MODULE_ALIAS("platform:leds-lt3593");



static int __init lt3593_led_init(void)

{

	return platform_driver_register(&lt3593_led_driver);

}



static void __exit lt3593_led_exit(void)

{

	platform_driver_unregister(&lt3593_led_driver);

}



module_init(lt3593_led_init);

module_exit(lt3593_led_exit);



MODULE_AUTHOR("Daniel Mack <daniel@caiaq.de>");

MODULE_DESCRIPTION("LED driver for LT3593 controllers");

MODULE_LICENSE("GPL");