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+=================================================
+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