leds: simple driver for pwm driven LEDs

Add a simple driver for pwm driver LEDs.  pwm_id and period can be defined
in board file.  It is developed for pxa, however it is probably generic
enough to be used on other platforms with pwm.

Signed-off-by: Luotao Fu <l.fu@pengutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>

diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
index 6a2f441..43f2654 100644 (file)
--- a/drivers/leds/Kconfig
+++ b/drivers/leds/Kconfig
@@ -184,6 +184,12 @@ config LEDS_PCA955X
          LED driver chips accessed via the I2C bus.  Supported
          devices include PCA9550, PCA9551, PCA9552, and PCA9553.
 
+config LEDS_PWM
+       tristate "PWM driven LED Support"
+       depends on LEDS_CLASS && HAVE_PWM
+       help
+         This option enables support for pwm driven LEDs
+
 comment "LED Triggers"
 
 config LEDS_TRIGGERS

diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
index fd6316e..6de2120 100644 (file)
--- a/drivers/leds/Makefile
+++ b/drivers/leds/Makefile
@@ -25,6 +25,7 @@ obj-$(CONFIG_LEDS_CLEVO_MAIL)         += leds-clevo-mail.o
 obj-$(CONFIG_LEDS_HP6XX)               += leds-hp6xx.o
 obj-$(CONFIG_LEDS_FSG)                 += leds-fsg.o
 obj-$(CONFIG_LEDS_PCA955X)             += leds-pca955x.o
+obj-$(CONFIG_LEDS_PWM)                 += leds-pwm.o
 
 # LED Triggers
 obj-$(CONFIG_LEDS_TRIGGER_TIMER)       += ledtrig-timer.o

diff --git a/drivers/leds/leds-pwm.c b/drivers/leds/leds-pwm.c
new file mode 100644 (file)
index 0000000..cdfdc87
--- /dev/null
+++ b/drivers/leds/leds-pwm.c
@@ -0,0 +1,153 @@
+/*
+ * linux/drivers/leds-pwm.c
+ *
+ * simple PWM based LED control
+ *
+ * Copyright 2009 Luotao Fu @ Pengutronix (l.fu@pengutronix.de)
+ *
+ * based on leds-gpio.c by Raphael Assenat <raph@8d.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.
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/platform_device.h>
+#include <linux/fb.h>
+#include <linux/leds.h>
+#include <linux/err.h>
+#include <linux/pwm.h>
+#include <linux/leds_pwm.h>
+
+struct led_pwm_data {
+       struct led_classdev     cdev;
+       struct pwm_device       *pwm;
+       unsigned int            active_low;
+       unsigned int            period;
+       unsigned int            max_brightness;
+};
+
+static void led_pwm_set(struct led_classdev *led_cdev,
+       enum led_brightness brightness)
+{
+       struct led_pwm_data *led_dat =
+               container_of(led_cdev, struct led_pwm_data, cdev);
+       unsigned int max = led_dat->max_brightness;
+       unsigned int period =  led_dat->period;
+
+       if (brightness == 0) {
+               pwm_config(led_dat->pwm, 0, period);
+               pwm_disable(led_dat->pwm);
+       } else {
+               pwm_config(led_dat->pwm, brightness * period / max, period);
+               pwm_enable(led_dat->pwm);
+       }
+}
+
+static int led_pwm_probe(struct platform_device *pdev)
+{
+       struct led_pwm_platform_data *pdata = pdev->dev.platform_data;
+       struct led_pwm *cur_led;
+       struct led_pwm_data *leds_data, *led_dat;
+       int i, ret = 0;
+
+       if (!pdata)
+               return -EBUSY;
+
+       leds_data = kzalloc(sizeof(struct led_pwm_data) * pdata->num_leds,
+                               GFP_KERNEL);
+       if (!leds_data)
+               return -ENOMEM;
+
+       for (i = 0; i < pdata->num_leds; i++) {
+               cur_led = &pdata->leds[i];
+               led_dat = &leds_data[i];
+
+               led_dat->pwm = pwm_request(cur_led->pwm_id,
+                               cur_led->name);
+               if (IS_ERR(led_dat->pwm)) {
+                       dev_err(&pdev->dev, "unable to request PWM %d\n",
+                                       cur_led->pwm_id);
+                       goto err;
+               }
+
+               led_dat->cdev.name = cur_led->name;
+               led_dat->cdev.default_trigger = cur_led->default_trigger;
+               led_dat->active_low = cur_led->active_low;
+               led_dat->max_brightness = cur_led->max_brightness;
+               led_dat->period = cur_led->pwm_period_ns;
+               led_dat->cdev.brightness_set = led_pwm_set;
+               led_dat->cdev.brightness = LED_OFF;
+               led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME;
+
+               ret = led_classdev_register(&pdev->dev, &led_dat->cdev);
+               if (ret < 0) {
+                       pwm_free(led_dat->pwm);
+                       goto err;
+               }
+       }
+
+       platform_set_drvdata(pdev, leds_data);
+
+       return 0;
+
+err:
+       if (i > 0) {
+               for (i = i - 1; i >= 0; i--) {
+                       led_classdev_unregister(&leds_data[i].cdev);
+                       pwm_free(leds_data[i].pwm);
+               }
+       }
+
+       kfree(leds_data);
+
+       return ret;
+}
+
+static int __devexit led_pwm_remove(struct platform_device *pdev)
+{
+       int i;
+       struct led_pwm_platform_data *pdata = pdev->dev.platform_data;
+       struct led_pwm_data *leds_data;
+
+       leds_data = platform_get_drvdata(pdev);
+
+       for (i = 0; i < pdata->num_leds; i++) {
+               led_classdev_unregister(&leds_data[i].cdev);
+               pwm_free(leds_data[i].pwm);
+       }
+
+       kfree(leds_data);
+
+       return 0;
+}
+
+static struct platform_driver led_pwm_driver = {
+       .probe          = led_pwm_probe,
+       .remove         = __devexit_p(led_pwm_remove),
+       .driver         = {
+               .name   = "leds_pwm",
+               .owner  = THIS_MODULE,
+       },
+};
+
+static int __init led_pwm_init(void)
+{
+       return platform_driver_register(&led_pwm_driver);
+}
+
+static void __exit led_pwm_exit(void)
+{
+       platform_driver_unregister(&led_pwm_driver);
+}
+
+module_init(led_pwm_init);
+module_exit(led_pwm_exit);
+
+MODULE_AUTHOR("Luotao Fu <l.fu@pengutronix.de>");
+MODULE_DESCRIPTION("PWM LED driver for PXA");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:leds-pwm");

diff --git a/include/linux/leds_pwm.h b/include/linux/leds_pwm.h
new file mode 100644 (file)
index 0000000..33a0711
--- /dev/null
+++ b/include/linux/leds_pwm.h
@@ -0,0 +1,21 @@
+/*
+ * PWM LED driver data - see drivers/leds/leds-pwm.c
+ */
+#ifndef __LINUX_LEDS_PWM_H
+#define __LINUX_LEDS_PWM_H
+
+struct led_pwm {
+       const char      *name;
+       const char      *default_trigger;
+       unsigned        pwm_id;
+       u8              active_low;
+       unsigned        max_brightness;
+       unsigned        pwm_period_ns;
+};
+
+struct led_pwm_platform_data {
+       int                     num_leds;
+       struct led_pwm  *leds;
+};
+
+#endif