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Documentation / leds / leds-lp55xx.txt




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Based on kernel version 3.13. Page generated on 2014-01-20 22:03 EST.

1	LP5521/LP5523/LP55231/LP5562/LP8501 Common Driver
2	=================================================
3	
4	Authors: Milo(Woogyom) Kim <milo.kim@ti.com>
5	
6	Description
7	-----------
8	LP5521, LP5523/55231, LP5562 and LP8501 have common features as below.
9	
10	  Register access via the I2C
11	  Device initialization/deinitialization
12	  Create LED class devices for multiple output channels
13	  Device attributes for user-space interface
14	  Program memory for running LED patterns
15	
16	The LP55xx common driver provides these features using exported functions.
17	  lp55xx_init_device() / lp55xx_deinit_device()
18	  lp55xx_register_leds() / lp55xx_unregister_leds()
19	  lp55xx_regsister_sysfs() / lp55xx_unregister_sysfs()
20	
21	( Driver Structure Data )
22	
23	In lp55xx common driver, two different data structure is used.
24	
25	o lp55xx_led
26	  control multi output LED channels such as led current, channel index.
27	o lp55xx_chip
28	  general chip control such like the I2C and platform data.
29	
30	For example, LP5521 has maximum 3 LED channels.
31	LP5523/55231 has 9 output channels.
32	
33	lp55xx_chip for LP5521 ... lp55xx_led #1
34	                           lp55xx_led #2
35	                           lp55xx_led #3
36	
37	lp55xx_chip for LP5523 ... lp55xx_led #1
38	                           lp55xx_led #2
39	                                 .
40	                                 .
41	                           lp55xx_led #9
42	
43	( Chip Dependent Code )
44	
45	To support device specific configurations, special structure
46	'lpxx_device_config' is used.
47	
48	  Maximum number of channels
49	  Reset command, chip enable command
50	  Chip specific initialization
51	  Brightness control register access
52	  Setting LED output current
53	  Program memory address access for running patterns
54	  Additional device specific attributes
55	
56	( Firmware Interface )
57	
58	LP55xx family devices have the internal program memory for running
59	various LED patterns.
60	This pattern data is saved as a file in the user-land or
61	hex byte string is written into the memory through the I2C.
62	LP55xx common driver supports the firmware interface.
63	
64	LP55xx chips have three program engines.
65	To load and run the pattern, the programming sequence is following.
66	  (1) Select an engine number (1/2/3)
67	  (2) Mode change to load
68	  (3) Write pattern data into selected area
69	  (4) Mode change to run
70	
71	The LP55xx common driver provides simple interfaces as below.
72	select_engine : Select which engine is used for running program
73	run_engine    : Start program which is loaded via the firmware interface
74	firmware      : Load program data
75	
76	For example, run blinking pattern in engine #1 of LP5521
77	echo 1 > /sys/bus/i2c/devices/xxxx/select_engine
78	echo 1 > /sys/class/firmware/lp5521/loading
79	echo "4000600040FF6000" > /sys/class/firmware/lp5521/data
80	echo 0 > /sys/class/firmware/lp5521/loading
81	echo 1 > /sys/bus/i2c/devices/xxxx/run_engine
82	
83	For example, run blinking pattern in engine #3 of LP55231
84	echo 3 > /sys/bus/i2c/devices/xxxx/select_engine
85	echo 1 > /sys/class/firmware/lp55231/loading
86	echo "9d0740ff7e0040007e00a0010000" > /sys/class/firmware/lp55231/data
87	echo 0 > /sys/class/firmware/lp55231/loading
88	echo 1 > /sys/bus/i2c/devices/xxxx/run_engine
89	
90	To start blinking patterns in engine #2 and #3 simultaneously,
91	for idx in 2 3
92	do
93	  echo $idx > /sys/class/leds/red/device/select_engine
94	  sleep 0.1
95	  echo 1 > /sys/class/firmware/lp5521/loading
96	  echo "4000600040FF6000" > /sys/class/firmware/lp5521/data
97	  echo 0 > /sys/class/firmware/lp5521/loading
98	done
99	echo 1 > /sys/class/leds/red/device/run_engine
100	
101	Here is another example for LP5523.
102	echo 2 > /sys/bus/i2c/devices/xxxx/select_engine
103	echo 1 > /sys/class/firmware/lp5523/loading
104	echo "9d80400004ff05ff437f0000" > /sys/class/firmware/lp5523/data
105	echo 0 > /sys/class/firmware/lp5523/loading
106	echo 1 > /sys/bus/i2c/devices/xxxx/run_engine
107	
108	As soon as 'loading' is set to 0, registered callback is called.
109	Inside the callback, the selected engine is loaded and memory is updated.
110	To run programmed pattern, 'run_engine' attribute should be enabled.
111	
112	The pattern sqeuence of LP8501 is same as LP5523.
113	However pattern data is specific.
114	Ex 1) Engine 1 is used
115	echo 1 > /sys/bus/i2c/devices/xxxx/select_engine
116	echo 1 > /sys/class/firmware/lp8501/loading
117	echo "9d0140ff7e0040007e00a001c000" > /sys/class/firmware/lp8501/data
118	echo 0 > /sys/class/firmware/lp8501/loading
119	echo 1 > /sys/bus/i2c/devices/xxxx/run_engine
120	
121	Ex 2) Engine 2 and 3 are used at the same time
122	echo 2 > /sys/bus/i2c/devices/xxxx/select_engine
123	sleep 1
124	echo 1 > /sys/class/firmware/lp8501/loading
125	echo "9d0140ff7e0040007e00a001c000" > /sys/class/firmware/lp8501/data
126	echo 0 > /sys/class/firmware/lp8501/loading
127	sleep 1
128	echo 3 > /sys/bus/i2c/devices/xxxx/select_engine
129	sleep 1
130	echo 1 > /sys/class/firmware/lp8501/loading
131	echo "9d0340ff7e0040007e00a001c000" > /sys/class/firmware/lp8501/data
132	echo 0 > /sys/class/firmware/lp8501/loading
133	sleep 1
134	echo 1 > /sys/class/leds/d1/device/run_engine
135	
136	( 'run_engine' and 'firmware_cb' )
137	The sequence of running the program data is common.
138	But each device has own specific register addresses for commands.
139	To support this, 'run_engine' and 'firmware_cb' are configurable in each driver.
140	run_engine  : Control the selected engine
141	firmware_cb : The callback function after loading the firmware is done.
142	              Chip specific commands for loading and updating program memory.
143	
144	( Predefined pattern data )
145	
146	Without the firmware interface, LP55xx driver provides another method for
147	loading a LED pattern. That is 'predefined' pattern.
148	A predefined pattern is defined in the platform data and load it(or them)
149	via the sysfs if needed.
150	To use the predefined pattern concept, 'patterns' and 'num_patterns' should be
151	configured.
152	
153	  Example of predefined pattern data:
154	
155	  /* mode_1: blinking data */
156	  static const u8 mode_1[] = {
157			0x40, 0x00, 0x60, 0x00, 0x40, 0xFF, 0x60, 0x00,
158			};
159	
160	  /* mode_2: always on */
161	  static const u8 mode_2[] = { 0x40, 0xFF, };
162	
163	  struct lp55xx_predef_pattern board_led_patterns[] = {
164		{
165			.r = mode_1,
166			.size_r = ARRAY_SIZE(mode_1),
167		},
168		{
169			.b = mode_2,
170			.size_b = ARRAY_SIZE(mode_2),
171		},
172	  }
173	
174	  struct lp55xx_platform_data lp5562_pdata = {
175	  ...
176		.patterns      = board_led_patterns,
177		.num_patterns  = ARRAY_SIZE(board_led_patterns),
178	  };
179	
180	Then, mode_1 and mode_2 can be run via through the sysfs.
181	
182	  echo 1 > /sys/bus/i2c/devices/xxxx/led_pattern    # red blinking LED pattern
183	  echo 2 > /sys/bus/i2c/devices/xxxx/led_pattern    # blue LED always on
184	
185	To stop running pattern,
186	  echo 0 > /sys/bus/i2c/devices/xxxx/led_pattern
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