Documentation: leds-lp5521,lp5523: update device attribute information

Now, all legacy application interfaces are restored.
Each driver documentation is updated.

Cc: Pali Rohár <pali.rohar@gmail.com>
Signed-off-by: Milo Kim <milo.kim@ti.com>
Signed-off-by: Bryan Wu <cooloney@gmail.com>
diff --git a/Documentation/leds/leds-lp5521.txt b/Documentation/leds/leds-lp5521.txt
index 79e4c2e..d08d8c1 100644
--- a/Documentation/leds/leds-lp5521.txt
+++ b/Documentation/leds/leds-lp5521.txt
@@ -18,7 +18,25 @@
 More details of the instructions can be found from the public data sheet.
 
 LP5521 has the internal program memory for running various LED patterns.
-For the details, please refer to 'firmware' section in leds-lp55xx.txt
+There are two ways to run LED patterns.
+
+1) Legacy interface - enginex_mode and enginex_load
+  Control interface for the engines:
+  x is 1 .. 3
+  enginex_mode : disabled, load, run
+  enginex_load : store program (visible only in engine load mode)
+
+  Example (start to blink the channel 2 led):
+  cd   /sys/class/leds/lp5521:channel2/device
+  echo "load" > engine3_mode
+  echo "037f4d0003ff6000" > engine3_load
+  echo "run" > engine3_mode
+
+  To stop the engine:
+  echo "disabled" > engine3_mode
+
+2) Firmware interface - LP55xx common interface
+  For the details, please refer to 'firmware' section in leds-lp55xx.txt
 
 sysfs contains a selftest entry.
 The test communicates with the chip and checks that