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author | Kim, Milo <Milo.Kim@ti.com> | 2012-03-23 15:02:01 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2012-03-23 16:58:33 -0700 |
commit | 7be865ab8634d4ec2a6bdb9459b268cd60e832af (patch) | |
tree | d7b73134707935d0bf6a912fa96e6dfcef47676a /Documentation | |
parent | 050ea48bbfc80b6aa81f8df0d9f25e6e47d96e98 (diff) | |
download | linux-stable-7be865ab8634d4ec2a6bdb9459b268cd60e832af.tar.gz linux-stable-7be865ab8634d4ec2a6bdb9459b268cd60e832af.tar.bz2 linux-stable-7be865ab8634d4ec2a6bdb9459b268cd60e832af.zip |
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>
Diffstat (limited to 'Documentation')
-rw-r--r-- | Documentation/backlight/lp855x-driver.txt | 78 |
1 files changed, 78 insertions, 0 deletions
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 <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. +* 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, + }, +}; |