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: Daniel Mack <daniel@caiaq.de> Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>
This commit is contained in:
Daniel Mack
Richard Purdie
parent
09a46db05b
commit
a8dd18feb6
3 changed files with 226 additions and 0 deletions
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@ -245,6 +245,14 @@ config LEDS_INTEL_SS4200
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drive or power LEDs on the front panel. Using this driver
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can stop the front LED from blinking after startup.
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config LEDS_LT3593
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tristate "LED driver for LT3593 controllers"
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depends on LEDS_CLASS && GENERIC_GPIO
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help
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This option enables support for LEDs driven by a Linear Technology
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LT3593 controller. This controller uses a special one-wire pulse
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coding protocol to set the brightness.
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comment "LED Triggers"
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config LEDS_TRIGGERS
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@ -30,6 +30,7 @@ obj-$(CONFIG_LEDS_WM831X_STATUS) += leds-wm831x-status.o
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obj-$(CONFIG_LEDS_WM8350) += leds-wm8350.o
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obj-$(CONFIG_LEDS_PWM) += leds-pwm.o
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obj-$(CONFIG_LEDS_INTEL_SS4200) += leds-ss4200.o
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obj-$(CONFIG_LEDS_LT3593) += leds-lt3593.o
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# LED SPI Drivers
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obj-$(CONFIG_LEDS_DAC124S085) += leds-dac124s085.o
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217
drivers/leds/leds-lt3593.c
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217
drivers/leds/leds-lt3593.c
Normal file
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@ -0,0 +1,217 @@
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/*
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* LEDs driver for LT3593 controllers
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*
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* See the datasheet at http://cds.linear.com/docs/Datasheet/3593f.pdf
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*
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* Copyright (c) 2009 Daniel Mack <daniel@caiaq.de>
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*
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* Based on leds-gpio.c,
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*
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* Copyright (C) 2007 8D Technologies inc.
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* Raphael Assenat <raph@8d.com>
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* Copyright (C) 2008 Freescale Semiconductor, Inc.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/kernel.h>
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#include <linux/init.h>
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#include <linux/platform_device.h>
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#include <linux/leds.h>
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#include <linux/workqueue.h>
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#include <linux/delay.h>
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#include <linux/gpio.h>
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struct lt3593_led_data {
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struct led_classdev cdev;
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unsigned gpio;
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struct work_struct work;
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u8 new_level;
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};
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static void lt3593_led_work(struct work_struct *work)
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{
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int pulses;
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struct lt3593_led_data *led_dat =
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container_of(work, struct lt3593_led_data, work);
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/*
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* The LT3593 resets its internal current level register to the maximum
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* level on the first falling edge on the control pin. Each following
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* falling edge decreases the current level by 625uA. Up to 32 pulses
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* can be sent, so the maximum power reduction is 20mA.
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* After a timeout of 128us, the value is taken from the register and
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* applied is to the output driver.
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*/
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if (led_dat->new_level == 0) {
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gpio_set_value_cansleep(led_dat->gpio, 0);
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return;
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}
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pulses = 32 - (led_dat->new_level * 32) / 255;
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if (pulses == 0) {
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gpio_set_value_cansleep(led_dat->gpio, 0);
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mdelay(1);
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gpio_set_value_cansleep(led_dat->gpio, 1);
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return;
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}
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gpio_set_value_cansleep(led_dat->gpio, 1);
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while (pulses--) {
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gpio_set_value_cansleep(led_dat->gpio, 0);
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udelay(1);
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gpio_set_value_cansleep(led_dat->gpio, 1);
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udelay(1);
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}
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}
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static void lt3593_led_set(struct led_classdev *led_cdev,
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enum led_brightness value)
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{
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struct lt3593_led_data *led_dat =
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container_of(led_cdev, struct lt3593_led_data, cdev);
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led_dat->new_level = value;
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schedule_work(&led_dat->work);
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}
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static int __devinit create_lt3593_led(const struct gpio_led *template,
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struct lt3593_led_data *led_dat, struct device *parent)
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{
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int ret, state;
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/* skip leds on GPIOs that aren't available */
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if (!gpio_is_valid(template->gpio)) {
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printk(KERN_INFO "%s: skipping unavailable LT3593 LED at gpio %d (%s)\n",
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KBUILD_MODNAME, template->gpio, template->name);
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return 0;
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}
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ret = gpio_request(template->gpio, template->name);
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if (ret < 0)
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return ret;
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led_dat->cdev.name = template->name;
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led_dat->cdev.default_trigger = template->default_trigger;
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led_dat->gpio = template->gpio;
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led_dat->cdev.brightness_set = lt3593_led_set;
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state = (template->default_state == LEDS_GPIO_DEFSTATE_ON);
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led_dat->cdev.brightness = state ? LED_FULL : LED_OFF;
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if (!template->retain_state_suspended)
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led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME;
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ret = gpio_direction_output(led_dat->gpio, state);
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if (ret < 0)
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goto err;
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INIT_WORK(&led_dat->work, lt3593_led_work);
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ret = led_classdev_register(parent, &led_dat->cdev);
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if (ret < 0)
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goto err;
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printk(KERN_INFO "%s: registered LT3593 LED '%s' at GPIO %d\n",
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KBUILD_MODNAME, template->name, template->gpio);
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return 0;
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err:
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gpio_free(led_dat->gpio);
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return ret;
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}
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static void delete_lt3593_led(struct lt3593_led_data *led)
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{
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if (!gpio_is_valid(led->gpio))
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return;
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led_classdev_unregister(&led->cdev);
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cancel_work_sync(&led->work);
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gpio_free(led->gpio);
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}
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static int __devinit lt3593_led_probe(struct platform_device *pdev)
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{
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struct gpio_led_platform_data *pdata = pdev->dev.platform_data;
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struct lt3593_led_data *leds_data;
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int i, ret = 0;
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if (!pdata)
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return -EBUSY;
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leds_data = kzalloc(sizeof(struct lt3593_led_data) * pdata->num_leds,
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GFP_KERNEL);
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if (!leds_data)
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return -ENOMEM;
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for (i = 0; i < pdata->num_leds; i++) {
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ret = create_lt3593_led(&pdata->leds[i], &leds_data[i],
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&pdev->dev);
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if (ret < 0)
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goto err;
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}
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platform_set_drvdata(pdev, leds_data);
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return 0;
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err:
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for (i = i - 1; i >= 0; i--)
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delete_lt3593_led(&leds_data[i]);
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kfree(leds_data);
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return ret;
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}
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static int __devexit lt3593_led_remove(struct platform_device *pdev)
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{
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int i;
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struct gpio_led_platform_data *pdata = pdev->dev.platform_data;
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struct lt3593_led_data *leds_data;
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leds_data = platform_get_drvdata(pdev);
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for (i = 0; i < pdata->num_leds; i++)
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delete_lt3593_led(&leds_data[i]);
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kfree(leds_data);
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return 0;
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}
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static struct platform_driver lt3593_led_driver = {
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.probe = lt3593_led_probe,
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.remove = __devexit_p(lt3593_led_remove),
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.driver = {
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.name = "leds-lt3593",
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.owner = THIS_MODULE,
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},
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};
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MODULE_ALIAS("platform:leds-lt3593");
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static int __init lt3593_led_init(void)
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{
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return platform_driver_register(<3593_led_driver);
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}
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static void __exit lt3593_led_exit(void)
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{
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platform_driver_unregister(<3593_led_driver);
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}
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module_init(lt3593_led_init);
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module_exit(lt3593_led_exit);
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MODULE_AUTHOR("Daniel Mack <daniel@caiaq.de>");
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MODULE_DESCRIPTION("LED driver for LT3593 controllers");
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MODULE_LICENSE("GPL");
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