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eb790aee17
Fix spelling mistakes in leds-lp55xx.txt file to make documentation clear. Signed-off-by: Tamara Diaconita <diaconita.tamara@gmail.com> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
195 lines
6.7 KiB
Plaintext
195 lines
6.7 KiB
Plaintext
LP5521/LP5523/LP55231/LP5562/LP8501 Common Driver
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=================================================
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Authors: Milo(Woogyom) Kim <milo.kim@ti.com>
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Description
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-----------
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LP5521, LP5523/55231, LP5562 and LP8501 have common features as below.
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Register access via the I2C
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Device initialization/deinitialization
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Create LED class devices for multiple output channels
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Device attributes for user-space interface
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Program memory for running LED patterns
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The LP55xx common driver provides these features using exported functions.
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lp55xx_init_device() / lp55xx_deinit_device()
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lp55xx_register_leds() / lp55xx_unregister_leds()
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lp55xx_regsister_sysfs() / lp55xx_unregister_sysfs()
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( Driver Structure Data )
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In lp55xx common driver, two different data structure is used.
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o lp55xx_led
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control multi output LED channels such as led current, channel index.
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o lp55xx_chip
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general chip control such like the I2C and platform data.
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For example, LP5521 has maximum 3 LED channels.
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LP5523/55231 has 9 output channels.
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lp55xx_chip for LP5521 ... lp55xx_led #1
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lp55xx_led #2
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lp55xx_led #3
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lp55xx_chip for LP5523 ... lp55xx_led #1
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lp55xx_led #2
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.
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.
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lp55xx_led #9
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( Chip Dependent Code )
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To support device specific configurations, special structure
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'lpxx_device_config' is used.
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Maximum number of channels
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Reset command, chip enable command
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Chip specific initialization
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Brightness control register access
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Setting LED output current
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Program memory address access for running patterns
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Additional device specific attributes
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( Firmware Interface )
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LP55xx family devices have the internal program memory for running
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various LED patterns.
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This pattern data is saved as a file in the user-land or
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hex byte string is written into the memory through the I2C.
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LP55xx common driver supports the firmware interface.
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LP55xx chips have three program engines.
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To load and run the pattern, the programming sequence is following.
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(1) Select an engine number (1/2/3)
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(2) Mode change to load
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(3) Write pattern data into selected area
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(4) Mode change to run
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The LP55xx common driver provides simple interfaces as below.
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select_engine : Select which engine is used for running program
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run_engine : Start program which is loaded via the firmware interface
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firmware : Load program data
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In case of LP5523, one more command is required, 'enginex_leds'.
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It is used for selecting LED output(s) at each engine number.
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In more details, please refer to 'leds-lp5523.txt'.
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For example, run blinking pattern in engine #1 of LP5521
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echo 1 > /sys/bus/i2c/devices/xxxx/select_engine
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echo 1 > /sys/class/firmware/lp5521/loading
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echo "4000600040FF6000" > /sys/class/firmware/lp5521/data
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echo 0 > /sys/class/firmware/lp5521/loading
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echo 1 > /sys/bus/i2c/devices/xxxx/run_engine
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For example, run blinking pattern in engine #3 of LP55231
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Two LEDs are configured as pattern output channels.
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echo 3 > /sys/bus/i2c/devices/xxxx/select_engine
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echo 1 > /sys/class/firmware/lp55231/loading
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echo "9d0740ff7e0040007e00a0010000" > /sys/class/firmware/lp55231/data
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echo 0 > /sys/class/firmware/lp55231/loading
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echo "000001100" > /sys/bus/i2c/devices/xxxx/engine3_leds
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echo 1 > /sys/bus/i2c/devices/xxxx/run_engine
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To start blinking patterns in engine #2 and #3 simultaneously,
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for idx in 2 3
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do
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echo $idx > /sys/class/leds/red/device/select_engine
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sleep 0.1
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echo 1 > /sys/class/firmware/lp5521/loading
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echo "4000600040FF6000" > /sys/class/firmware/lp5521/data
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echo 0 > /sys/class/firmware/lp5521/loading
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done
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echo 1 > /sys/class/leds/red/device/run_engine
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Here is another example for LP5523.
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Full LED strings are selected by 'engine2_leds'.
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echo 2 > /sys/bus/i2c/devices/xxxx/select_engine
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echo 1 > /sys/class/firmware/lp5523/loading
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echo "9d80400004ff05ff437f0000" > /sys/class/firmware/lp5523/data
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echo 0 > /sys/class/firmware/lp5523/loading
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echo "111111111" > /sys/bus/i2c/devices/xxxx/engine2_leds
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echo 1 > /sys/bus/i2c/devices/xxxx/run_engine
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As soon as 'loading' is set to 0, registered callback is called.
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Inside the callback, the selected engine is loaded and memory is updated.
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To run programmed pattern, 'run_engine' attribute should be enabled.
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The pattern sequence of LP8501 is similar to LP5523.
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However pattern data is specific.
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Ex 1) Engine 1 is used
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echo 1 > /sys/bus/i2c/devices/xxxx/select_engine
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echo 1 > /sys/class/firmware/lp8501/loading
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echo "9d0140ff7e0040007e00a001c000" > /sys/class/firmware/lp8501/data
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echo 0 > /sys/class/firmware/lp8501/loading
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echo 1 > /sys/bus/i2c/devices/xxxx/run_engine
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Ex 2) Engine 2 and 3 are used at the same time
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echo 2 > /sys/bus/i2c/devices/xxxx/select_engine
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sleep 1
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echo 1 > /sys/class/firmware/lp8501/loading
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echo "9d0140ff7e0040007e00a001c000" > /sys/class/firmware/lp8501/data
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echo 0 > /sys/class/firmware/lp8501/loading
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sleep 1
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echo 3 > /sys/bus/i2c/devices/xxxx/select_engine
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sleep 1
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echo 1 > /sys/class/firmware/lp8501/loading
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echo "9d0340ff7e0040007e00a001c000" > /sys/class/firmware/lp8501/data
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echo 0 > /sys/class/firmware/lp8501/loading
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sleep 1
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echo 1 > /sys/class/leds/d1/device/run_engine
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( 'run_engine' and 'firmware_cb' )
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The sequence of running the program data is common.
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But each device has own specific register addresses for commands.
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To support this, 'run_engine' and 'firmware_cb' are configurable in each driver.
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run_engine : Control the selected engine
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firmware_cb : The callback function after loading the firmware is done.
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Chip specific commands for loading and updating program memory.
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( Predefined pattern data )
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Without the firmware interface, LP55xx driver provides another method for
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loading a LED pattern. That is 'predefined' pattern.
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A predefined pattern is defined in the platform data and load it(or them)
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via the sysfs if needed.
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To use the predefined pattern concept, 'patterns' and 'num_patterns' should be
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configured.
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Example of predefined pattern data:
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/* mode_1: blinking data */
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static const u8 mode_1[] = {
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0x40, 0x00, 0x60, 0x00, 0x40, 0xFF, 0x60, 0x00,
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};
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/* mode_2: always on */
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static const u8 mode_2[] = { 0x40, 0xFF, };
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struct lp55xx_predef_pattern board_led_patterns[] = {
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{
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.r = mode_1,
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.size_r = ARRAY_SIZE(mode_1),
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},
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{
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.b = mode_2,
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.size_b = ARRAY_SIZE(mode_2),
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},
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}
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struct lp55xx_platform_data lp5562_pdata = {
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...
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.patterns = board_led_patterns,
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.num_patterns = ARRAY_SIZE(board_led_patterns),
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};
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Then, mode_1 and mode_2 can be run via through the sysfs.
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echo 1 > /sys/bus/i2c/devices/xxxx/led_pattern # red blinking LED pattern
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echo 2 > /sys/bus/i2c/devices/xxxx/led_pattern # blue LED always on
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To stop running pattern,
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echo 0 > /sys/bus/i2c/devices/xxxx/led_pattern
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