leds: add new lp8788 led driver

TI LP8788 PMU has the current sink as the keyboard led driver.
The brightness is controlled by the i2c commands.
Configurable parameters can be defined in the platform side.

Patch v2.
(a) use workqueue on changing the brightness

(b) use mutex_lock/unlock when the brightness is set
    and the led block of lp8788 device is enabled

(c) remove err_dev on _probe()
    : just return as returned value if any errors

(d) replace module_init/exit() with module_platform_driver()

(e) add led configuration structure and loading them by default
    if platform data is null
Signed-off-by: Milo(Woogyom) Kim <milo.kim@ti.com>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Bryan Wu <bryan.wu@canonical.com>

drivers/leds/Kconfig

@@ -200,6 +200,13 @@ config LEDS_LP5523
 	  Driver provides direct control via LED class and interface for
 	  programming the engines.
 
+config LEDS_LP8788
+	tristate "LED support for the TI LP8788 PMIC"
+	depends on LEDS_CLASS
+	depends on MFD_LP8788
+	help
+	  This option enables support for the Keyboard LEDs on the LP8788 PMIC.
+
 config LEDS_CLEVO_MAIL
 	tristate "Mail LED on Clevo notebook"
 	depends on LEDS_CLASS

drivers/leds/Makefile

@@ -24,6 +24,7 @@ obj-$(CONFIG_LEDS_GPIO)			+= leds-gpio.o
 obj-$(CONFIG_LEDS_LP3944)		+= leds-lp3944.o
 obj-$(CONFIG_LEDS_LP5521)		+= leds-lp5521.o
 obj-$(CONFIG_LEDS_LP5523)		+= leds-lp5523.o
+obj-$(CONFIG_LEDS_LP8788)		+= leds-lp8788.o
 obj-$(CONFIG_LEDS_TCA6507)		+= leds-tca6507.o
 obj-$(CONFIG_LEDS_CLEVO_MAIL)		+= leds-clevo-mail.o
 obj-$(CONFIG_LEDS_HP6XX)		+= leds-hp6xx.o

drivers/leds/leds-lp8788.c

+/*
+ * TI LP8788 MFD - keyled driver
+ *
+ * Copyright 2012 Texas Instruments
+ *
+ * Author: Milo(Woogyom) Kim <milo.kim@ti.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/slab.h>
+#include <linux/err.h>
+#include <linux/platform_device.h>
+#include <linux/leds.h>
+#include <linux/mutex.h>
+#include <linux/mfd/lp8788.h>
+#include <linux/mfd/lp8788-isink.h>
+
+#define MAX_BRIGHTNESS			LP8788_ISINK_MAX_PWM
+#define DEFAULT_LED_NAME		"keyboard-backlight"
+
+struct lp8788_led {
+	struct lp8788 *lp;
+	struct mutex lock;
+	struct work_struct work;
+	struct led_classdev led_dev;
+	enum lp8788_isink_number isink_num;
+	enum led_brightness brightness;
+	int on;
+};
+
+struct lp8788_led_config {
+	enum lp8788_isink_scale scale;
+	enum lp8788_isink_number num;
+	int iout;
+};
+
+static struct lp8788_led_config default_led_config = {
+	.scale = LP8788_ISINK_SCALE_100mA,
+	.num   = LP8788_ISINK_3,
+	.iout  = 0,
+};
+
+static int lp8788_led_init_device(struct lp8788_led *led,
+				struct lp8788_led_platform_data *pdata)
+{
+	struct lp8788_led_config *cfg = &default_led_config;
+	u8 addr, mask, val;
+	int ret;
+
+	if (pdata) {
+		cfg->scale = pdata->scale;
+		cfg->num = pdata->num;
+		cfg->iout = pdata->iout_code;
+	}
+
+	led->isink_num = cfg->num;
+
+	/* scale configuration */
+	addr = LP8788_ISINK_CTRL;
+	mask = 1 << (cfg->num + LP8788_ISINK_SCALE_OFFSET);
+	val = cfg->scale << cfg->num;
+	ret = lp8788_update_bits(led->lp, addr, mask, val);
+	if (ret)
+		return ret;
+
+	/* current configuration */
+	addr = lp8788_iout_addr[cfg->num];
+	mask = lp8788_iout_mask[cfg->num];
+	val = cfg->iout;
+
+	return lp8788_update_bits(led->lp, addr, mask, val);
+}
+
+static void lp8788_led_enable(struct lp8788_led *led,
+			enum lp8788_isink_number num, int on)
+{
+	u8 mask = 1 << num;
+	u8 val = on << num;
+
+	if (lp8788_update_bits(led->lp, LP8788_ISINK_CTRL, mask, val))
+		return;
+
+	led->on = on;
+}
+
+static void lp8788_led_work(struct work_struct *work)
+{
+	struct lp8788_led *led = container_of(work, struct lp8788_led, work);
+	enum lp8788_isink_number num = led->isink_num;
+	int enable;
+	u8 val = led->brightness;
+
+	mutex_lock(&led->lock);
+
+	switch (num) {
+	case LP8788_ISINK_1:
+	case LP8788_ISINK_2:
+	case LP8788_ISINK_3:
+		lp8788_write_byte(led->lp, lp8788_pwm_addr[num], val);
+		break;
+	default:
+		return;
+	}
+
+	enable = (val > 0) ? 1 : 0;
+	if (enable != led->on)
+		lp8788_led_enable(led, num, enable);
+
+	mutex_unlock(&led->lock);
+}
+
+static void lp8788_brightness_set(struct led_classdev *led_cdev,
+				enum led_brightness brt_val)
+{
+	struct lp8788_led *led =
+			container_of(led_cdev, struct lp8788_led, led_dev);
+
+	led->brightness = brt_val;
+	schedule_work(&led->work);
+}
+
+static __devinit int lp8788_led_probe(struct platform_device *pdev)
+{
+	struct lp8788 *lp = dev_get_drvdata(pdev->dev.parent);
+	struct lp8788_led_platform_data *led_pdata;
+	struct lp8788_led *led;
+	int ret;
+
+	led = devm_kzalloc(lp->dev, sizeof(struct lp8788_led), GFP_KERNEL);
+	if (!led)
+		return -ENOMEM;
+
+	led->lp = lp;
+	led->led_dev.max_brightness = MAX_BRIGHTNESS;
+	led->led_dev.brightness_set = lp8788_brightness_set;
+
+	led_pdata = lp->pdata ? lp->pdata->led_pdata : NULL;
+
+	if (!led_pdata || !led_pdata->name)
+		led->led_dev.name = DEFAULT_LED_NAME;
+	else
+		led->led_dev.name = led_pdata->name;
+
+	mutex_init(&led->lock);
+	INIT_WORK(&led->work, lp8788_led_work);
+
+	platform_set_drvdata(pdev, led);
+
+	ret = lp8788_led_init_device(led, led_pdata);
+	if (ret) {
+		dev_err(lp->dev, "led init device err: %d\n", ret);
+		return ret;
+	}
+
+	ret = led_classdev_register(lp->dev, &led->led_dev);
+	if (ret) {
+		dev_err(lp->dev, "led register err: %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static int __devexit lp8788_led_remove(struct platform_device *pdev)
+{
+	struct lp8788_led *led = platform_get_drvdata(pdev);
+
+	led_classdev_unregister(&led->led_dev);
+	flush_work_sync(&led->work);
+
+	return 0;
+}
+
+static struct platform_driver lp8788_led_driver = {
+	.probe = lp8788_led_probe,
+	.remove = __devexit_p(lp8788_led_remove),
+	.driver = {
+		.name = LP8788_DEV_KEYLED,
+		.owner = THIS_MODULE,
+	},
+};
+module_platform_driver(lp8788_led_driver);
+
+MODULE_DESCRIPTION("Texas Instruments LP8788 Keyboard LED Driver");
+MODULE_AUTHOR("Milo Kim");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:lp8788-keyled");