From 7be865ab8634d4ec2a6bdb9459b268cd60e832af Mon Sep 17 00:00:00 2001 From: Kim, Milo Date: Fri, 23 Mar 2012 15:02:01 -0700 Subject: 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 Signed-off-by: Axel Lin Signed-off-by: Dan Carpenter Cc: Richard Purdie Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/backlight/lp855x-driver.txt | 78 +++++++++++++++++++++++++++++++ 1 file changed, 78 insertions(+) create mode 100644 Documentation/backlight/lp855x-driver.txt (limited to 'Documentation/backlight') diff --git a/Documentation/backlight/lp855x-driver.txt b/Documentation/backlight/lp855x-driver.txt new file mode 100644 index 000000000000..f5e4caafab7d --- /dev/null +++ b/Documentation/backlight/lp855x-driver.txt @@ -0,0 +1,78 @@ +Kernel driver lp855x +==================== + +Backlight driver for LP855x ICs + +Supported chips: + Texas Instruments LP8550, LP8551, LP8552, LP8553 and LP8556 + +Author: Milo(Woogyom) Kim + +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. +* 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, + .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, + .pwm_data = { + .pwm_set_intensity = platform_pwm_set_intensity, + .pwm_get_intensity = platform_pwm_get_intensity, + }, +}; -- cgit v1.2.3