leds: lp5523: Support LED MUX configuration on running a pattern

There are two ways to run a pattern in LP5523.
One is using legacy sysfs files such as 'enginex_mode','enginex_load' and
'enginex_leds'. ('x' is from 1 to 3).
Among them, 'enginex_leds' are used for selecting specific LED channel MUX.
(MUX means which LEDs are used for running a pattern from LED 1 to 9.)

The other way is using the firmware interface.
In this mode, the default LED MUX strings are used.
In other words, LED MUX is not configurable on the fly.

This patch enables dynamic LED MUX configuration when the firmware is loaded.
By accessing the sysfs file 'enginex_leds', the LED channels can be configured.
To synchronize the operation mode, each engine mode should be set to 'LOAD'.

The documentation is updated as well.

Cc: Pali Rohár <[e-mail]>
Signed-off-by: Milo Kim <[e-mail]>
Signed-off-by: Bryan Wu <[e-mail]>

Documentation/leds/leds-lp55xx.txt

···
 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 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,
···
 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 same as LP5523.
+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

drivers/leds/leds-lp55xx-common.c

···
 {
 	struct lp55xx_chip *chip = context;
 	struct device *dev = &chip->cl->dev;
+	enum lp55xx_engine_index idx = chip->engine_idx;
 
 	if (!fw) {
 		dev_err(dev, "firmware request failed\n");
···
 	/* handling firmware data is chip dependent */
 	mutex_lock(&chip->lock);
 
+	chip->engines[idx - 1].mode = LP55XX_ENGINE_LOAD;
 	chip->fw = fw;
 	if (chip->cfg->firmware_cb)
 		chip->cfg->firmware_cb(chip);