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Diffstat (limited to 'Documentation/leds/leds-lp55xx.txt')
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diff --git a/Documentation/leds/leds-lp55xx.txt b/Documentation/leds/leds-lp55xx.txt new file mode 100644 index 000000000..bcea12a0c --- /dev/null +++ b/Documentation/leds/leds-lp55xx.txt @@ -0,0 +1,194 @@ +LP5521/LP5523/LP55231/LP5562/LP8501 Common Driver +================================================= + +Authors: Milo(Woogyom) Kim <milo.kim@ti.com> + +Description +----------- +LP5521, LP5523/55231, LP5562 and LP8501 have common features as below. + + Register access via the I2C + Device initialization/deinitialization + Create LED class devices for multiple output channels + Device attributes for user-space interface + Program memory for running LED patterns + +The LP55xx common driver provides these features using exported functions. + lp55xx_init_device() / lp55xx_deinit_device() + lp55xx_register_leds() / lp55xx_unregister_leds() + lp55xx_regsister_sysfs() / lp55xx_unregister_sysfs() + +( Driver Structure Data ) + +In lp55xx common driver, two different data structure is used. + +o lp55xx_led + control multi output LED channels such as led current, channel index. +o lp55xx_chip + general chip control such like the I2C and platform data. + +For example, LP5521 has maximum 3 LED channels. +LP5523/55231 has 9 output channels. + +lp55xx_chip for LP5521 ... lp55xx_led #1 + lp55xx_led #2 + lp55xx_led #3 + +lp55xx_chip for LP5523 ... lp55xx_led #1 + lp55xx_led #2 + . + . + lp55xx_led #9 + +( Chip Dependent Code ) + +To support device specific configurations, special structure +'lpxx_device_config' is used. + + Maximum number of channels + Reset command, chip enable command + Chip specific initialization + Brightness control register access + Setting LED output current + Program memory address access for running patterns + Additional device specific attributes + +( Firmware Interface ) + +LP55xx family devices have the internal program memory for running +various LED patterns. +This pattern data is saved as a file in the user-land or +hex byte string is written into the memory through the I2C. +LP55xx common driver supports the firmware interface. + +LP55xx chips have three program engines. +To load and run the pattern, the programming sequence is following. + (1) Select an engine number (1/2/3) + (2) Mode change to load + (3) Write pattern data into selected area + (4) Mode change to run + +The LP55xx common driver provides simple interfaces as below. +select_engine : Select which engine is used for running program +run_engine : Start program which is loaded via the firmware interface +firmware : Load program data + +In case of LP5523, one more command is required, 'enginex_leds'. +It is used for selecting LED output(s) at each engine number. +In more details, please refer to 'leds-lp5523.txt'. + +For example, run blinking pattern in engine #1 of LP5521 +echo 1 > /sys/bus/i2c/devices/xxxx/select_engine +echo 1 > /sys/class/firmware/lp5521/loading +echo "4000600040FF6000" > /sys/class/firmware/lp5521/data +echo 0 > /sys/class/firmware/lp5521/loading +echo 1 > /sys/bus/i2c/devices/xxxx/run_engine + +For example, run blinking pattern in engine #3 of LP55231 +Two LEDs are configured as pattern output channels. +echo 3 > /sys/bus/i2c/devices/xxxx/select_engine +echo 1 > /sys/class/firmware/lp55231/loading +echo "9d0740ff7e0040007e00a0010000" > /sys/class/firmware/lp55231/data +echo 0 > /sys/class/firmware/lp55231/loading +echo "000001100" > /sys/bus/i2c/devices/xxxx/engine3_leds +echo 1 > /sys/bus/i2c/devices/xxxx/run_engine + +To start blinking patterns in engine #2 and #3 simultaneously, +for idx in 2 3 +do + echo $idx > /sys/class/leds/red/device/select_engine + sleep 0.1 + echo 1 > /sys/class/firmware/lp5521/loading + echo "4000600040FF6000" > /sys/class/firmware/lp5521/data + echo 0 > /sys/class/firmware/lp5521/loading +done +echo 1 > /sys/class/leds/red/device/run_engine + +Here is another example for LP5523. +Full LED strings are selected by 'engine2_leds'. +echo 2 > /sys/bus/i2c/devices/xxxx/select_engine +echo 1 > /sys/class/firmware/lp5523/loading +echo "9d80400004ff05ff437f0000" > /sys/class/firmware/lp5523/data +echo 0 > /sys/class/firmware/lp5523/loading +echo "111111111" > /sys/bus/i2c/devices/xxxx/engine2_leds +echo 1 > /sys/bus/i2c/devices/xxxx/run_engine + +As soon as 'loading' is set to 0, registered callback is called. +Inside the callback, the selected engine is loaded and memory is updated. +To run programmed pattern, 'run_engine' attribute should be enabled. + +The pattern sqeuence of LP8501 is similar to LP5523. +However pattern data is specific. +Ex 1) Engine 1 is used +echo 1 > /sys/bus/i2c/devices/xxxx/select_engine +echo 1 > /sys/class/firmware/lp8501/loading +echo "9d0140ff7e0040007e00a001c000" > /sys/class/firmware/lp8501/data +echo 0 > /sys/class/firmware/lp8501/loading +echo 1 > /sys/bus/i2c/devices/xxxx/run_engine + +Ex 2) Engine 2 and 3 are used at the same time +echo 2 > /sys/bus/i2c/devices/xxxx/select_engine +sleep 1 +echo 1 > /sys/class/firmware/lp8501/loading +echo "9d0140ff7e0040007e00a001c000" > /sys/class/firmware/lp8501/data +echo 0 > /sys/class/firmware/lp8501/loading +sleep 1 +echo 3 > /sys/bus/i2c/devices/xxxx/select_engine +sleep 1 +echo 1 > /sys/class/firmware/lp8501/loading +echo "9d0340ff7e0040007e00a001c000" > /sys/class/firmware/lp8501/data +echo 0 > /sys/class/firmware/lp8501/loading +sleep 1 +echo 1 > /sys/class/leds/d1/device/run_engine + +( 'run_engine' and 'firmware_cb' ) +The sequence of running the program data is common. +But each device has own specific register addresses for commands. +To support this, 'run_engine' and 'firmware_cb' are configurable in each driver. +run_engine : Control the selected engine +firmware_cb : The callback function after loading the firmware is done. + Chip specific commands for loading and updating program memory. + +( Predefined pattern data ) + +Without the firmware interface, LP55xx driver provides another method for +loading a LED pattern. That is 'predefined' pattern. +A predefined pattern is defined in the platform data and load it(or them) +via the sysfs if needed. +To use the predefined pattern concept, 'patterns' and 'num_patterns' should be +configured. + + Example of predefined pattern data: + + /* mode_1: blinking data */ + static const u8 mode_1[] = { + 0x40, 0x00, 0x60, 0x00, 0x40, 0xFF, 0x60, 0x00, + }; + + /* mode_2: always on */ + static const u8 mode_2[] = { 0x40, 0xFF, }; + + struct lp55xx_predef_pattern board_led_patterns[] = { + { + .r = mode_1, + .size_r = ARRAY_SIZE(mode_1), + }, + { + .b = mode_2, + .size_b = ARRAY_SIZE(mode_2), + }, + } + + struct lp55xx_platform_data lp5562_pdata = { + ... + .patterns = board_led_patterns, + .num_patterns = ARRAY_SIZE(board_led_patterns), + }; + +Then, mode_1 and mode_2 can be run via through the sysfs. + + echo 1 > /sys/bus/i2c/devices/xxxx/led_pattern # red blinking LED pattern + echo 2 > /sys/bus/i2c/devices/xxxx/led_pattern # blue LED always on + +To stop running pattern, + echo 0 > /sys/bus/i2c/devices/xxxx/led_pattern |