backlight: new backlight driver for LP855x devices

THis driver supports TI LP8550/LP8551/LP8552/LP8553/LP8556 backlight
devices.

The brightness can be controlled by the I2C or PWM input.  The lp855x
driver provides both modes.  For the PWM control, pwm-specific functions
can be defined in the platform data.  And some information can be read
via the sysfs(lp855x device attributes).

For details, please refer to Documentation/backlight/lp855x-driver.txt.

[axel.lin@gmail.com: add missing mutex_unlock in lp855x_read_byte() error path]
[axel.lin@gmail.com: check platform data in lp855x_probe()]
[axel.lin@gmail.com: small cleanups]
[dan.carpenter@oracle.com: silence a compiler warning]
[axel.lin@gmail.com: use id->driver_data to differentiate lp855x chips]
[akpm@linux-foundation.org: simplify boolean return expression]
Signed-off-by: Milo(Woogyom) Kim <milo.kim@ti.com>
Signed-off-by: Axel Lin <axel.lin@gmail.com>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 339 insertions, 0 deletions

diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig
index 681b36929fe..49e7d83f869 100644
--- a/drivers/video/backlight/Kconfig
+++ b/drivers/video/backlight/Kconfig
@@ -334,6 +334,13 @@ config BACKLIGHT_AAT2870
 	  If you have a AnalogicTech AAT2870 say Y to enable the
 	  backlight driver.
 
+config BACKLIGHT_LP855X
+	tristate "Backlight driver for TI LP855X"
+	depends on BACKLIGHT_CLASS_DEVICE && I2C
+	help
+	  This supports TI LP8550, LP8551, LP8552, LP8553 and LP8556
+	  backlight driver.
+
 endif # BACKLIGHT_CLASS_DEVICE
 
 endif # BACKLIGHT_LCD_SUPPORT
diff --git a/drivers/video/backlight/Makefile b/drivers/video/backlight/Makefile
index af5cf654ec7..0ee06e0832b 100644
--- a/drivers/video/backlight/Makefile
+++ b/drivers/video/backlight/Makefile
@@ -22,6 +22,7 @@ obj-$(CONFIG_BACKLIGHT_GENERIC)	+= generic_bl.o
 obj-$(CONFIG_BACKLIGHT_HP700)	+= jornada720_bl.o
 obj-$(CONFIG_BACKLIGHT_HP680)	+= hp680_bl.o
 obj-$(CONFIG_BACKLIGHT_LOCOMO)	+= locomolcd.o
+obj-$(CONFIG_BACKLIGHT_LP855X)	+= lp855x_bl.o
 obj-$(CONFIG_BACKLIGHT_OMAP1)	+= omap1_bl.o
 obj-$(CONFIG_BACKLIGHT_PROGEAR) += progear_bl.o
 obj-$(CONFIG_BACKLIGHT_CARILLO_RANCH) += cr_bllcd.o
diff --git a/drivers/video/backlight/lp855x_bl.c b/drivers/video/backlight/lp855x_bl.c
new file mode 100644
index 00000000000..72a0e0c917c
--- /dev/null
+++ b/drivers/video/backlight/lp855x_bl.c
@@ -0,0 +1,331 @@
+/*
+ * TI LP855x Backlight Driver
+ *
+ *			Copyright (C) 2011 Texas Instruments
+ *
+ * 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/i2c.h>
+#include <linux/backlight.h>
+#include <linux/err.h>
+#include <linux/lp855x.h>
+
+/* Registers */
+#define BRIGHTNESS_CTRL		(0x00)
+#define DEVICE_CTRL		(0x01)
+
+#define BUF_SIZE		20
+#define DEFAULT_BL_NAME		"lcd-backlight"
+#define MAX_BRIGHTNESS		255
+
+struct lp855x {
+	const char *chipname;
+	enum lp855x_chip_id chip_id;
+	struct i2c_client *client;
+	struct backlight_device *bl;
+	struct device *dev;
+	struct mutex xfer_lock;
+	struct lp855x_platform_data *pdata;
+};
+
+static int lp855x_read_byte(struct lp855x *lp, u8 reg, u8 *data)
+{
+	int ret;
+
+	mutex_lock(&lp->xfer_lock);
+	ret = i2c_smbus_read_byte_data(lp->client, reg);
+	if (ret < 0) {
+		mutex_unlock(&lp->xfer_lock);
+		dev_err(lp->dev, "failed to read 0x%.2x\n", reg);
+		return ret;
+	}
+	mutex_unlock(&lp->xfer_lock);
+
+	*data = (u8)ret;
+	return 0;
+}
+
+static int lp855x_write_byte(struct lp855x *lp, u8 reg, u8 data)
+{
+	int ret;
+
+	mutex_lock(&lp->xfer_lock);
+	ret = i2c_smbus_write_byte_data(lp->client, reg, data);
+	mutex_unlock(&lp->xfer_lock);
+
+	return ret;
+}
+
+static bool lp855x_is_valid_rom_area(struct lp855x *lp, u8 addr)
+{
+	u8 start, end;
+
+	switch (lp->chip_id) {
+	case LP8550:
+	case LP8551:
+	case LP8552:
+	case LP8553:
+		start = EEPROM_START;
+		end = EEPROM_END;
+		break;
+	case LP8556:
+		start = EPROM_START;
+		end = EPROM_END;
+		break;
+	default:
+		return false;
+	}
+
+	return (addr >= start && addr <= end);
+}
+
+static int lp855x_init_registers(struct lp855x *lp)
+{
+	u8 val, addr;
+	int i, ret;
+	struct lp855x_platform_data *pd = lp->pdata;
+
+	val = pd->initial_brightness;
+	ret = lp855x_write_byte(lp, BRIGHTNESS_CTRL, val);
+	if (ret)
+		return ret;
+
+	val = pd->device_control;
+	ret = lp855x_write_byte(lp, DEVICE_CTRL, val);
+	if (ret)
+		return ret;
+
+	if (pd->load_new_rom_data && pd->size_program) {
+		for (i = 0; i < pd->size_program; i++) {
+			addr = pd->rom_data[i].addr;
+			val = pd->rom_data[i].val;
+			if (!lp855x_is_valid_rom_area(lp, addr))
+				continue;
+
+			ret = lp855x_write_byte(lp, addr, val);
+			if (ret)
+				return ret;
+		}
+	}
+
+	return ret;
+}
+
+static int lp855x_bl_update_status(struct backlight_device *bl)
+{
+	struct lp855x *lp = bl_get_data(bl);
+	enum lp855x_brightness_ctrl_mode mode = lp->pdata->mode;
+
+	if (bl->props.state & BL_CORE_SUSPENDED)
+		bl->props.brightness = 0;
+
+	if (mode == PWM_BASED) {
+		struct lp855x_pwm_data *pd = &lp->pdata->pwm_data;
+		int br = bl->props.brightness;
+		int max_br = bl->props.max_brightness;
+
+		if (pd->pwm_set_intensity)
+			pd->pwm_set_intensity(br, max_br);
+
+	} else if (mode == REGISTER_BASED) {
+		u8 val = bl->props.brightness;
+		lp855x_write_byte(lp, BRIGHTNESS_CTRL, val);
+	}
+
+	return 0;
+}
+
+static int lp855x_bl_get_brightness(struct backlight_device *bl)
+{
+	struct lp855x *lp = bl_get_data(bl);
+	enum lp855x_brightness_ctrl_mode mode = lp->pdata->mode;
+
+	if (mode == PWM_BASED) {
+		struct lp855x_pwm_data *pd = &lp->pdata->pwm_data;
+		int max_br = bl->props.max_brightness;
+
+		if (pd->pwm_get_intensity)
+			bl->props.brightness = pd->pwm_get_intensity(max_br);
+
+	} else if (mode == REGISTER_BASED) {
+		u8 val = 0;
+
+		lp855x_read_byte(lp, BRIGHTNESS_CTRL, &val);
+		bl->props.brightness = val;
+	}
+
+	return bl->props.brightness;
+}
+
+static const struct backlight_ops lp855x_bl_ops = {
+	.options = BL_CORE_SUSPENDRESUME,
+	.update_status = lp855x_bl_update_status,
+	.get_brightness = lp855x_bl_get_brightness,
+};
+
+static int lp855x_backlight_register(struct lp855x *lp)
+{
+	struct backlight_device *bl;
+	struct backlight_properties props;
+	struct lp855x_platform_data *pdata = lp->pdata;
+	char *name = pdata->name ? : DEFAULT_BL_NAME;
+
+	props.type = BACKLIGHT_PLATFORM;
+	props.max_brightness = MAX_BRIGHTNESS;
+
+	if (pdata->initial_brightness > props.max_brightness)
+		pdata->initial_brightness = props.max_brightness;
+
+	props.brightness = pdata->initial_brightness;
+
+	bl = backlight_device_register(name, lp->dev, lp,
+				       &lp855x_bl_ops, &props);
+	if (IS_ERR(bl))
+		return PTR_ERR(bl);
+
+	lp->bl = bl;
+
+	return 0;
+}
+
+static void lp855x_backlight_unregister(struct lp855x *lp)
+{
+	if (lp->bl)
+		backlight_device_unregister(lp->bl);
+}
+
+static ssize_t lp855x_get_chip_id(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	struct lp855x *lp = dev_get_drvdata(dev);
+	return scnprintf(buf, BUF_SIZE, "%s\n", lp->chipname);
+}
+
+static ssize_t lp855x_get_bl_ctl_mode(struct device *dev,
+				     struct device_attribute *attr, char *buf)
+{
+	struct lp855x *lp = dev_get_drvdata(dev);
+	enum lp855x_brightness_ctrl_mode mode = lp->pdata->mode;
+	char *strmode = NULL;
+
+	if (mode == PWM_BASED)
+		strmode = "pwm based";
+	else if (mode == REGISTER_BASED)
+		strmode = "register based";
+
+	return scnprintf(buf, BUF_SIZE, "%s\n", strmode);
+}
+
+static DEVICE_ATTR(chip_id, S_IRUGO, lp855x_get_chip_id, NULL);
+static DEVICE_ATTR(bl_ctl_mode, S_IRUGO, lp855x_get_bl_ctl_mode, NULL);
+
+static struct attribute *lp855x_attributes[] = {
+	&dev_attr_chip_id.attr,
+	&dev_attr_bl_ctl_mode.attr,
+	NULL,
+};
+
+static const struct attribute_group lp855x_attr_group = {
+	.attrs = lp855x_attributes,
+};
+
+static int lp855x_probe(struct i2c_client *cl, const struct i2c_device_id *id)
+{
+	struct lp855x *lp;
+	struct lp855x_platform_data *pdata = cl->dev.platform_data;
+	enum lp855x_brightness_ctrl_mode mode;
+	int ret;
+
+	if (!pdata) {
+		dev_err(&cl->dev, "no platform data supplied\n");
+		return -EINVAL;
+	}
+
+	if (!i2c_check_functionality(cl->adapter, I2C_FUNC_SMBUS_I2C_BLOCK))
+		return -EIO;
+
+	lp = devm_kzalloc(&cl->dev, sizeof(struct lp855x), GFP_KERNEL);
+	if (!lp)
+		return -ENOMEM;
+
+	mode = pdata->mode;
+	lp->client = cl;
+	lp->dev = &cl->dev;
+	lp->pdata = pdata;
+	lp->chipname = id->name;
+	lp->chip_id = id->driver_data;
+	i2c_set_clientdata(cl, lp);
+
+	mutex_init(&lp->xfer_lock);
+
+	ret = lp855x_init_registers(lp);
+	if (ret) {
+		dev_err(lp->dev, "i2c communication err: %d", ret);
+		if (mode == REGISTER_BASED)
+			goto err_dev;
+	}
+
+	ret = lp855x_backlight_register(lp);
+	if (ret) {
+		dev_err(lp->dev,
+			"failed to register backlight. err: %d\n", ret);
+		goto err_dev;
+	}
+
+	ret = sysfs_create_group(&lp->dev->kobj, &lp855x_attr_group);
+	if (ret) {
+		dev_err(lp->dev, "failed to register sysfs. err: %d\n", ret);
+		goto err_sysfs;
+	}
+
+	backlight_update_status(lp->bl);
+	return 0;
+
+err_sysfs:
+	lp855x_backlight_unregister(lp);
+err_dev:
+	return ret;
+}
+
+static int __devexit lp855x_remove(struct i2c_client *cl)
+{
+	struct lp855x *lp = i2c_get_clientdata(cl);
+
+	lp->bl->props.brightness = 0;
+	backlight_update_status(lp->bl);
+	sysfs_remove_group(&lp->dev->kobj, &lp855x_attr_group);
+	lp855x_backlight_unregister(lp);
+
+	return 0;
+}
+
+static const struct i2c_device_id lp855x_ids[] = {
+	{"lp8550", LP8550},
+	{"lp8551", LP8551},
+	{"lp8552", LP8552},
+	{"lp8553", LP8553},
+	{"lp8556", LP8556},
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, lp855x_ids);
+
+static struct i2c_driver lp855x_driver = {
+	.driver = {
+		   .name = "lp855x",
+		   },
+	.probe = lp855x_probe,
+	.remove = __devexit_p(lp855x_remove),
+	.id_table = lp855x_ids,
+};
+
+module_i2c_driver(lp855x_driver);
+
+MODULE_DESCRIPTION("Texas Instruments LP855x Backlight driver");
+MODULE_AUTHOR("Milo Kim <milo.kim@ti.com>");
+MODULE_LICENSE("GPL");