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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>
79 lines
2.2 KiB
Plaintext
79 lines
2.2 KiB
Plaintext
Kernel driver lp855x
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====================
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Backlight driver for LP855x ICs
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Supported chips:
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Texas Instruments LP8550, LP8551, LP8552, LP8553 and LP8556
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Author: Milo(Woogyom) Kim <milo.kim@ti.com>
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Description
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-----------
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* Brightness control
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Brightness can be controlled by the pwm input or the i2c command.
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The lp855x driver supports both cases.
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* Device attributes
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1) bl_ctl_mode
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Backlight control mode.
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Value : pwm based or register based
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2) chip_id
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The lp855x chip id.
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Value : lp8550/lp8551/lp8552/lp8553/lp8556
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Platform data for lp855x
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------------------------
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For supporting platform specific data, the lp855x platform data can be used.
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* name : Backlight driver name. If it is not defined, default name is set.
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* mode : Brightness control mode. PWM or register based.
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* device_control : Value of DEVICE CONTROL register.
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* initial_brightness : Initial value of backlight brightness.
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* pwm_data : Platform specific pwm generation functions.
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Only valid when brightness is pwm input mode.
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Functions should be implemented by PWM driver.
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- pwm_set_intensity() : set duty of PWM
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- pwm_get_intensity() : get current duty of PWM
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* load_new_rom_data :
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0 : use default configuration data
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1 : update values of eeprom or eprom registers on loading driver
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* size_program : Total size of lp855x_rom_data.
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* rom_data : List of new eeprom/eprom registers.
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example 1) lp8552 platform data : i2c register mode with new eeprom data
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#define EEPROM_A5_ADDR 0xA5
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#define EEPROM_A5_VAL 0x4f /* EN_VSYNC=0 */
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static struct lp855x_rom_data lp8552_eeprom_arr[] = {
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{EEPROM_A5_ADDR, EEPROM_A5_VAL},
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};
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static struct lp855x_platform_data lp8552_pdata = {
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.name = "lcd-bl",
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.mode = REGISTER_BASED,
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.device_control = I2C_CONFIG(LP8552),
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.initial_brightness = INITIAL_BRT,
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.load_new_rom_data = 1,
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.size_program = ARRAY_SIZE(lp8552_eeprom_arr),
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.rom_data = lp8552_eeprom_arr,
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};
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example 2) lp8556 platform data : pwm input mode with default rom data
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static struct lp855x_platform_data lp8556_pdata = {
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.mode = PWM_BASED,
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.device_control = PWM_CONFIG(LP8556),
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.initial_brightness = INITIAL_BRT,
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.pwm_data = {
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.pwm_set_intensity = platform_pwm_set_intensity,
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.pwm_get_intensity = platform_pwm_get_intensity,
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},
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};
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