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SubjectRE: [PATCH v2] backlight: new backlight driver for LP855x devices
* patch based on kernel 3.0.1

-----Original Message-----
From: Kim, Milo
Sent: Wednesday, January 25, 2012 3:24 PM
To: 'Andrew Morton'; 'linux-kernel@vger.kernel.org'
Cc: 'Richard Purdie'
Subject: [PATCH v2] backlight: new backlight driver for LP855x devices

This patch supports TI LP8550/LP8551/LP8852/LP8553/LP8556 backlight driver.

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

Signed-off-by: Milo(Woogyom) Kim <milo.kim@ti.com>
---
Documentation/backlight/lp855x-driver.txt | 81 +++++++
drivers/video/backlight/Kconfig | 7 +
drivers/video/backlight/Makefile | 1 +
drivers/video/backlight/lp855x_bl.c | 331 +++++++++++++++++++++++++++++
include/linux/lp855x.h | 133 ++++++++++++
5 files changed, 553 insertions(+), 0 deletions(-)
create mode 100644 Documentation/backlight/lp855x-driver.txt
create mode 100644 drivers/video/backlight/lp855x_bl.c
create mode 100644 include/linux/lp855x.h

diff --git a/Documentation/backlight/lp855x-driver.txt b/Documentation/backlight/lp855x-driver.txt
new file mode 100644
index 0000000..321351e
--- /dev/null
+++ b/Documentation/backlight/lp855x-driver.txt
@@ -0,0 +1,81 @@
+Kernel driver lp855x
+====================
+
+Backlight driver for LP855x ICs
+
+Supported chips:
+ Texas Instruments LP8550, LP8551, LP8552, LP8553 and LP8556
+
+Author: Milo(Woogyom) Kim <milo.kim@ti.com>
+
+Description
+-----------
+
+* Brightness control
+
+Brightness can be controlled by the pwm input or the i2c command.
+The lp855x driver supports both cases.
+
+* Device attributes
+
+1) bl_ctl_mode
+Backlight control mode.
+Value : pwm based or register based
+
+2) chip_id
+The lp855x chip id.
+Value : lp8550/lp8551/lp8552/lp8553/lp8556
+
+Platform data for lp855x
+------------------------
+
+For supporting platform specific data, the lp855x platform data can be used.
+
+* name : Backlight driver name. If it is not defined, default name is set.
+* mode : Brightness control mode. PWM or register based.
+* device_control : Value of DEVICE CONTROL register.
+* initial_brightness : Initial value of backlight brightness.
+* max_brightness : Maximum value of backlight brightness.
+* pwm_data : Platform specific pwm generation functions.
+ Only valid when brightness is pwm input mode.
+ Functions should be implemented by PWM driver.
+ - pwm_set_intensity() : set duty of PWM
+ - pwm_get_intensity() : get current duty of PWM
+* load_new_rom_data :
+ 0 : use default configuration data
+ 1 : update values of eeprom or eprom registers on loading driver
+* size_program : Total size of lp855x_rom_data.
+* rom_data : List of new eeprom/eprom registers.
+
+example 1) lp8552 platform data : i2c register mode with new eeprom data
+
+#define EEPROM_A5_ADDR 0xA5
+#define EEPROM_A5_VAL 0x4f /* EN_VSYNC=0 */
+
+static struct lp855x_rom_data lp8552_eeprom_arr[] = {
+ {EEPROM_A5_ADDR, EEPROM_A5_VAL},
+};
+
+static struct lp855x_platform_data lp8552_pdata = {
+ .name = "lcd-bl",
+ .mode = REGISTER_BASED,
+ .device_control = I2C_CONFIG(LP8552),
+ .initial_brightness = INITIAL_BRT,
+ .max_brightness = MAX_BRT,
+ .load_new_rom_data = 1,
+ .size_program = ARRAY_SIZE(lp8552_eeprom_arr),
+ .rom_data = lp8552_eeprom_arr,
+};
+
+example 2) lp8556 platform data : pwm input mode with default rom data
+
+static struct lp855x_platform_data lp8556_pdata = {
+ .mode = PWM_BASED,
+ .device_control = PWM_CONFIG(LP8556),
+ .initial_brightness = INITIAL_BRT,
+ .max_brightness = MAX_BRT,
+ .pwm_data = {
+ .pwm_set_intensity = platform_pwm_set_intensity,
+ .pwm_get_intensity = platform_pwm_get_intensity,
+ },
+};
diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig
index 2d93c8d..995088a 100644
--- a/drivers/video/backlight/Kconfig
+++ b/drivers/video/backlight/Kconfig
@@ -327,6 +327,13 @@ config BACKLIGHT_PCF50633
If you have a backlight driven by a NXP PCF50633 MFD, say Y here to
enable its 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 ee72adb..27788c9 100644
--- a/drivers/video/backlight/Makefile
+++ b/drivers/video/backlight/Makefile
@@ -37,4 +37,5 @@ obj-$(CONFIG_BACKLIGHT_ADP8860) += adp8860_bl.o
obj-$(CONFIG_BACKLIGHT_ADP8870) += adp8870_bl.o
obj-$(CONFIG_BACKLIGHT_88PM860X) += 88pm860x_bl.o
obj-$(CONFIG_BACKLIGHT_PCF50633) += pcf50633-backlight.o
+obj-$(CONFIG_BACKLIGHT_LP855X) += lp855x_bl.o

diff --git a/drivers/video/backlight/lp855x_bl.c b/drivers/video/backlight/lp855x_bl.c
new file mode 100644
index 0000000..d2d072d
--- /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/debugfs.h>
+#include <linux/uaccess.h>
+#include <linux/lp855x.h>
+
+/* Registers */
+#define BRIGHTNESS_CTRL (0x00)
+#define DEVICE_CTRL (0x01)
+
+#define BUF_SIZE (20)
+#define DEFAULT_BL_NAME "lcd-backlight"
+
+struct lp855x {
+ const char *chipid;
+ 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) {
+ 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 int lp855x_is_valid_rom_area(struct lp855x *lp, u8 addr)
+{
+ const char *id = lp->chipid;
+ u8 start, end;
+
+ if (strstr(id, "lp8550") || strstr(id, "lp8551")
+ || strstr(id, "lp8552") || strstr(id, "lp8553")) {
+ start = EEPROM_START;
+ end = EEPROM_END;
+ } else if (strstr(id, "lp8556")) {
+ start = EPROM_START;
+ end = EPROM_END;
+ }
+
+ return (addr >= start && addr <= end) ? 1 : 0;
+}
+
+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 (bl->props.brightness);
+}
+
+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.brightness = pdata->initial_brightness;
+ props.max_brightness =
+ (pdata->max_brightness < pdata->initial_brightness) ?
+ 255 : pdata->max_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->chipid);
+}
+
+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;
+ int ret;
+
+ if (!i2c_check_functionality(cl->adapter, I2C_FUNC_SMBUS_I2C_BLOCK))
+ goto err_io;
+
+ lp = kzalloc(sizeof(struct lp855x), GFP_KERNEL);
+ if (!lp)
+ goto err_mem;
+
+ lp->client = cl;
+ lp->dev = &cl->dev;
+ lp->pdata = pdata;
+ lp->chipid = id->name;
+ i2c_set_clientdata(cl, lp);
+
+ mutex_init(&lp->xfer_lock);
+
+ ret = lp855x_init_registers(lp);
+ if (ret)
+ goto err_i2c;
+
+ ret = lp855x_backlight_register(lp);
+ if (ret)
+ goto err_bldev;
+
+ ret = sysfs_create_group(&lp->dev->kobj, &lp855x_attr_group);
+ if (ret)
+ goto err_sysfs;
+
+ backlight_update_status(lp->bl);
+ return ret;
+
+err_io:
+ return -EIO;
+err_mem:
+ return -ENOMEM;
+err_i2c:
+ dev_err(lp->dev, "i2c communication err: %d", ret);
+ kfree(lp);
+ return ret;
+err_bldev:
+ dev_err(lp->dev, "can not register backlight device. err: %d\n", ret);
+ kfree(lp);
+ return ret;
+err_sysfs:
+ dev_err(lp->dev, "can not register sysfs. err: %d\n", ret);
+ lp855x_backlight_unregister(lp);
+ kfree(lp);
+ 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);
+ kfree(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,
+};
+
+static int __init lp855x_init(void)
+{
+ return i2c_add_driver(&lp855x_driver);
+}
+
+static void __exit lp855x_exit(void)
+{
+ i2c_del_driver(&lp855x_driver);
+}
+
+module_init(lp855x_init);
+module_exit(lp855x_exit);
+
+MODULE_DESCRIPTION("Texas Instruments LP855x Backlight driver");
+MODULE_AUTHOR("Milo Kim <milo.kim@ti.com>");
+MODULE_LICENSE("GPL");
diff --git a/include/linux/lp855x.h b/include/linux/lp855x.h
new file mode 100644
index 0000000..dd46713
--- /dev/null
+++ b/include/linux/lp855x.h
@@ -0,0 +1,133 @@
+/*
+ * 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.
+ *
+ */
+
+#ifndef _LP855X_H
+#define _LP855X_H
+
+#define BL_CTL_SHFT (0)
+#define BRT_MODE_SHFT (1)
+#define BRT_MODE_MASK (0x06)
+
+/* Enable backlight. Only valid when BRT_MODE=10(I2C only) */
+#define ENABLE_BL (1)
+#define DISABLE_BL (0)
+
+#define I2C_CONFIG(id) id ## _I2C_CONFIG
+#define PWM_CONFIG(id) id ## _PWM_CONFIG
+
+/* DEVICE CONTROL register - LP8550 */
+#define LP8550_PWM_CONFIG (LP8550_PWM_ONLY << BRT_MODE_SHFT)
+#define LP8550_I2C_CONFIG ((ENABLE_BL << BL_CTL_SHFT) | \
+ (LP8550_I2C_ONLY << BRT_MODE_SHFT))
+
+/* DEVICE CONTROL register - LP8551 */
+#define LP8551_PWM_CONFIG LP8550_PWM_CONFIG
+#define LP8551_I2C_CONFIG LP8550_I2C_CONFIG
+
+/* DEVICE CONTROL register - LP8552 */
+#define LP8552_PWM_CONFIG LP8550_PWM_CONFIG
+#define LP8552_I2C_CONFIG LP8550_I2C_CONFIG
+
+/* DEVICE CONTROL register - LP8553 */
+#define LP8553_PWM_CONFIG LP8550_PWM_CONFIG
+#define LP8553_I2C_CONFIG LP8550_I2C_CONFIG
+
+/* DEVICE CONTROL register - LP8556 */
+#define LP8556_PWM_CONFIG (LP8556_PWM_ONLY << BRT_MODE_SHFT)
+#define LP8556_COMB1_CONFIG (LP8556_COMBINED1 << BRT_MODE_SHFT)
+#define LP8556_I2C_CONFIG ((ENABLE_BL << BL_CTL_SHFT) | \
+ (LP8556_I2C_ONLY << BRT_MODE_SHFT))
+#define LP8556_COMB2_CONFIG (LP8556_COMBINED2 << BRT_MODE_SHFT)
+
+/* ROM area boundary */
+#define EEPROM_START (0xA0)
+#define EEPROM_END (0xA7)
+#define EPROM_START (0xA0)
+#define EPROM_END (0xAF)
+
+enum lp855x_chip_id {
+ LP8550,
+ LP8551,
+ LP8552,
+ LP8553,
+ LP8556,
+};
+
+enum lp855x_brightness_ctrl_mode {
+ PWM_BASED = 1,
+ REGISTER_BASED,
+};
+
+enum lp8550_brighntess_source {
+ LP8550_PWM_ONLY,
+ LP8550_I2C_ONLY = 2,
+};
+
+enum lp8551_brighntess_source {
+ LP8551_PWM_ONLY = LP8550_PWM_ONLY,
+ LP8551_I2C_ONLY = LP8550_I2C_ONLY,
+};
+
+enum lp8552_brighntess_source {
+ LP8552_PWM_ONLY = LP8550_PWM_ONLY,
+ LP8552_I2C_ONLY = LP8550_I2C_ONLY,
+};
+
+enum lp8553_brighntess_source {
+ LP8553_PWM_ONLY = LP8550_PWM_ONLY,
+ LP8553_I2C_ONLY = LP8550_I2C_ONLY,
+};
+
+enum lp8556_brightness_source {
+ LP8556_PWM_ONLY,
+ LP8556_COMBINED1, /* pwm + i2c before the shaper block */
+ LP8556_I2C_ONLY,
+ LP8556_COMBINED2, /* pwm + i2c after the shaper block */
+};
+
+struct lp855x_pwm_data {
+ void (*pwm_set_intensity) (int brightness, int max_brightness);
+ int (*pwm_get_intensity) (int max_brightness);
+};
+
+struct lp855x_rom_data {
+ u8 addr;
+ u8 val;
+};
+
+/**
+ * struct lp855x_platform_data
+ * @name : Backlight driver name. If it is not defined, default name is set.
+ * @mode : brightness control by pwm or lp855x register
+ * @device_control : value of DEVICE CONTROL register
+ * @initial_brightness : initial value of backlight brightness
+ * @max_brightness : maximum value of backlight brightness
+ * @pwm_data : platform specific pwm generation functions.
+ Only valid when mode is PWM_BASED.
+ * @load_new_rom_data :
+ 0 : use default configuration data
+ 1 : update values of eeprom or eprom registers on loading driver
+ * @size_program : total size of lp855x_rom_data
+ * @rom_data : list of new eeprom/eprom registers
+ */
+struct lp855x_platform_data {
+ char *name;
+ enum lp855x_brightness_ctrl_mode mode;
+ u8 device_control;
+ int initial_brightness;
+ int max_brightness;
+ struct lp855x_pwm_data pwm_data;
+ u8 load_new_rom_data;
+ int size_program;
+ struct lp855x_rom_data *rom_data;
+};
+
+#endif
--
1.7.4.1

Best Regards,
Milo (Woogyom) Kim
Texas Instruments Incorporated



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