summaryrefslogtreecommitdiffstats
path: root/Documentation/leds/leds-lp55xx.rst
diff options
context:
space:
mode:
Diffstat (limited to '')
-rw-r--r--Documentation/leds/leds-lp55xx.rst224
1 files changed, 224 insertions, 0 deletions
diff --git a/Documentation/leds/leds-lp55xx.rst b/Documentation/leds/leds-lp55xx.rst
new file mode 100644
index 000000000..632e41cec
--- /dev/null
+++ b/Documentation/leds/leds-lp55xx.rst
@@ -0,0 +1,224 @@
+=================================================
+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.
+
+* lp55xx_led
+ control multi output LED channels such as led current, channel index.
+* 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 sequence 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