leds: Add LED class driver for regulator driven LEDs.

This driver provides an interface for controlling LEDs (or vibrators)
connected to PMICs for which there is a regulator framework driver.

This driver can be used, for instance, to control vibrator on all Motorola EZX
phones using the pcap-regulator driver services.

Signed-off-by: Antonio Ospite <ospite@studenti.unina.it>
Reviewed-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>

1 files changed, 242 insertions, 0 deletions

diff --git a/drivers/leds/leds-regulator.c b/drivers/leds/leds-regulator.c
new file mode 100644
index 000000000000..7f00de3ef922
--- /dev/null
+++ b/drivers/leds/leds-regulator.c
@@ -0,0 +1,242 @@
+/*
+ * leds-regulator.c - LED class driver for regulator driven LEDs.
+ *
+ * Copyright (C) 2009 Antonio Ospite <ospite@studenti.unina.it>
+ *
+ * Inspired by leds-wm8350 driver.
+ *
+ * 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/err.h>
+#include <linux/workqueue.h>
+#include <linux/leds.h>
+#include <linux/leds-regulator.h>
+#include <linux/platform_device.h>
+#include <linux/regulator/consumer.h>
+
+#define to_regulator_led(led_cdev) \
+        container_of(led_cdev, struct regulator_led, cdev)
+
+struct regulator_led {
+        struct led_classdev cdev;
+        enum led_brightness value;
+        int enabled;
+        struct mutex mutex;
+        struct work_struct work;
+
+        struct regulator *vcc;
+};
+
+static inline int led_regulator_get_max_brightness(struct regulator *supply)
+{
+        int ret;
+        int voltage = regulator_list_voltage(supply, 0);
+
+        if (voltage <= 0)
+                return 1;
+
+        /* even if regulator can't change voltages,
+         * we still assume it can change status
+         * and the LED can be turned on and off.
+         */
+        ret = regulator_set_voltage(supply, voltage, voltage);
+        if (ret < 0)
+                return 1;
+
+        return regulator_count_voltages(supply);
+}
+
+static int led_regulator_get_voltage(struct regulator *supply,
+                enum led_brightness brightness)
+{
+        if (brightness == 0)
+                return -EINVAL;
+
+        return regulator_list_voltage(supply, brightness - 1);
+}
+
+
+static void regulator_led_enable(struct regulator_led *led)
+{
+        int ret;
+
+        if (led->enabled)
+                return;
+
+        ret = regulator_enable(led->vcc);
+        if (ret != 0) {
+                dev_err(led->cdev.dev, "Failed to enable vcc: %d\n", ret);
+                return;
+        }
+
+        led->enabled = 1;
+}
+
+static void regulator_led_disable(struct regulator_led *led)
+{
+        int ret;
+
+        if (!led->enabled)
+                return;
+
+        ret = regulator_disable(led->vcc);
+        if (ret != 0) {
+                dev_err(led->cdev.dev, "Failed to disable vcc: %d\n", ret);
+                return;
+        }
+
+        led->enabled = 0;
+}
+
+static void regulator_led_set_value(struct regulator_led *led)
+{
+        int voltage;
+        int ret;
+
+        mutex_lock(&led->mutex);
+
+        if (led->value == LED_OFF) {
+                regulator_led_disable(led);
+                goto out;
+        }
+
+        if (led->cdev.max_brightness > 1) {
+                voltage = led_regulator_get_voltage(led->vcc, led->value);
+                dev_dbg(led->cdev.dev, "brightness: %d voltage: %d\n",
+                                led->value, voltage);
+
+                ret = regulator_set_voltage(led->vcc, voltage, voltage);
+                if (ret != 0)
+                        dev_err(led->cdev.dev, "Failed to set voltage %d: %d\n",
+                                voltage, ret);
+        }
+
+        regulator_led_enable(led);
+
+out:
+        mutex_unlock(&led->mutex);
+}
+
+static void led_work(struct work_struct *work)
+{
+        struct regulator_led *led;
+
+        led = container_of(work, struct regulator_led, work);
+        regulator_led_set_value(led);
+}
+
+static void regulator_led_brightness_set(struct led_classdev *led_cdev,
+                           enum led_brightness value)
+{
+        struct regulator_led *led = to_regulator_led(led_cdev);
+
+        led->value = value;
+        schedule_work(&led->work);
+}
+
+static int __devinit regulator_led_probe(struct platform_device *pdev)
+{
+        struct led_regulator_platform_data *pdata = pdev->dev.platform_data;
+        struct regulator_led *led;
+        struct regulator *vcc;
+        int ret = 0;
+
+        if (pdata == NULL) {
+                dev_err(&pdev->dev, "no platform data\n");
+                return -ENODEV;
+        }
+
+        vcc = regulator_get_exclusive(&pdev->dev, "vled");
+        if (IS_ERR(vcc)) {
+                dev_err(&pdev->dev, "Cannot get vcc for %s\n", pdata->name);
+                return PTR_ERR(vcc);
+        }
+
+        led = kzalloc(sizeof(*led), GFP_KERNEL);
+        if (led == NULL) {
+                ret = -ENOMEM;
+                goto err_vcc;
+        }
+
+        led->cdev.max_brightness = led_regulator_get_max_brightness(vcc);
+        if (pdata->brightness > led->cdev.max_brightness) {
+                dev_err(&pdev->dev, "Invalid default brightness %d\n",
+                                pdata->brightness);
+                ret = -EINVAL;
+                goto err_led;
+        }
+        led->value = pdata->brightness;
+
+        led->cdev.brightness_set = regulator_led_brightness_set;
+        led->cdev.name = pdata->name;
+        led->cdev.flags |= LED_CORE_SUSPENDRESUME;
+        led->vcc = vcc;
+
+        mutex_init(&led->mutex);
+        INIT_WORK(&led->work, led_work);
+
+        platform_set_drvdata(pdev, led);
+
+        ret = led_classdev_register(&pdev->dev, &led->cdev);
+        if (ret < 0) {
+                cancel_work_sync(&led->work);
+                goto err_led;
+        }
+
+        /* to expose the default value to userspace */
+        led->cdev.brightness = led->value;
+
+        /* Set the default led status */
+        regulator_led_set_value(led);
+
+        return 0;
+
+err_led:
+        kfree(led);
+err_vcc:
+        regulator_put(vcc);
+        return ret;
+}
+
+static int __devexit regulator_led_remove(struct platform_device *pdev)
+{
+        struct regulator_led *led = platform_get_drvdata(pdev);
+
+        led_classdev_unregister(&led->cdev);
+        cancel_work_sync(&led->work);
+        regulator_led_disable(led);
+        regulator_put(led->vcc);
+        kfree(led);
+        return 0;
+}
+
+static struct platform_driver regulator_led_driver = {
+        .driver = {
+                   .name  = "leds-regulator",
+                   .owner = THIS_MODULE,
+                   },
+        .probe  = regulator_led_probe,
+        .remove = __devexit_p(regulator_led_remove),
+};
+
+static int __init regulator_led_init(void)
+{
+        return platform_driver_register(&regulator_led_driver);
+}
+module_init(regulator_led_init);
+
+static void __exit regulator_led_exit(void)
+{
+        platform_driver_unregister(&regulator_led_driver);
+}
+module_exit(regulator_led_exit);
+
+MODULE_AUTHOR("Antonio Ospite <ospite@studenti.unina.it>");
+MODULE_DESCRIPTION("Regulator driven LED driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:leds-regulator");