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Based on kernel version 3.15.4. Page generated on 2014-07-07 09:03 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	In case of LP5523, one more command is required, 'enginex_leds'.
77	It is used for selecting LED output(s) at each engine number.
78	In more details, please refer to 'leds-lp5523.txt'.
79	
80	For example, run blinking pattern in engine #1 of LP5521
81	echo 1 > /sys/bus/i2c/devices/xxxx/select_engine
82	echo 1 > /sys/class/firmware/lp5521/loading
83	echo "4000600040FF6000" > /sys/class/firmware/lp5521/data
84	echo 0 > /sys/class/firmware/lp5521/loading
85	echo 1 > /sys/bus/i2c/devices/xxxx/run_engine
86	
87	For example, run blinking pattern in engine #3 of LP55231
88	Two LEDs are configured as pattern output channels.
89	echo 3 > /sys/bus/i2c/devices/xxxx/select_engine
90	echo 1 > /sys/class/firmware/lp55231/loading
91	echo "9d0740ff7e0040007e00a0010000" > /sys/class/firmware/lp55231/data
92	echo 0 > /sys/class/firmware/lp55231/loading
93	echo "000001100" > /sys/bus/i2c/devices/xxxx/engine3_leds
94	echo 1 > /sys/bus/i2c/devices/xxxx/run_engine
95	
96	To start blinking patterns in engine #2 and #3 simultaneously,
97	for idx in 2 3
98	do
99	  echo $idx > /sys/class/leds/red/device/select_engine
100	  sleep 0.1
101	  echo 1 > /sys/class/firmware/lp5521/loading
102	  echo "4000600040FF6000" > /sys/class/firmware/lp5521/data
103	  echo 0 > /sys/class/firmware/lp5521/loading
104	done
105	echo 1 > /sys/class/leds/red/device/run_engine
106	
107	Here is another example for LP5523.
108	Full LED strings are selected by 'engine2_leds'.
109	echo 2 > /sys/bus/i2c/devices/xxxx/select_engine
110	echo 1 > /sys/class/firmware/lp5523/loading
111	echo "9d80400004ff05ff437f0000" > /sys/class/firmware/lp5523/data
112	echo 0 > /sys/class/firmware/lp5523/loading
113	echo "111111111" > /sys/bus/i2c/devices/xxxx/engine2_leds
114	echo 1 > /sys/bus/i2c/devices/xxxx/run_engine
115	
116	As soon as 'loading' is set to 0, registered callback is called.
117	Inside the callback, the selected engine is loaded and memory is updated.
118	To run programmed pattern, 'run_engine' attribute should be enabled.
119	
120	The pattern sqeuence of LP8501 is similar to LP5523.
121	However pattern data is specific.
122	Ex 1) Engine 1 is used
123	echo 1 > /sys/bus/i2c/devices/xxxx/select_engine
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	echo 1 > /sys/bus/i2c/devices/xxxx/run_engine
128	
129	Ex 2) Engine 2 and 3 are used at the same time
130	echo 2 > /sys/bus/i2c/devices/xxxx/select_engine
131	sleep 1
132	echo 1 > /sys/class/firmware/lp8501/loading
133	echo "9d0140ff7e0040007e00a001c000" > /sys/class/firmware/lp8501/data
134	echo 0 > /sys/class/firmware/lp8501/loading
135	sleep 1
136	echo 3 > /sys/bus/i2c/devices/xxxx/select_engine
137	sleep 1
138	echo 1 > /sys/class/firmware/lp8501/loading
139	echo "9d0340ff7e0040007e00a001c000" > /sys/class/firmware/lp8501/data
140	echo 0 > /sys/class/firmware/lp8501/loading
141	sleep 1
142	echo 1 > /sys/class/leds/d1/device/run_engine
143	
144	( 'run_engine' and 'firmware_cb' )
145	The sequence of running the program data is common.
146	But each device has own specific register addresses for commands.
147	To support this, 'run_engine' and 'firmware_cb' are configurable in each driver.
148	run_engine  : Control the selected engine
149	firmware_cb : The callback function after loading the firmware is done.
150	              Chip specific commands for loading and updating program memory.
151	
152	( Predefined pattern data )
153	
154	Without the firmware interface, LP55xx driver provides another method for
155	loading a LED pattern. That is 'predefined' pattern.
156	A predefined pattern is defined in the platform data and load it(or them)
157	via the sysfs if needed.
158	To use the predefined pattern concept, 'patterns' and 'num_patterns' should be
159	configured.
160	
161	  Example of predefined pattern data:
162	
163	  /* mode_1: blinking data */
164	  static const u8 mode_1[] = {
165			0x40, 0x00, 0x60, 0x00, 0x40, 0xFF, 0x60, 0x00,
166			};
167	
168	  /* mode_2: always on */
169	  static const u8 mode_2[] = { 0x40, 0xFF, };
170	
171	  struct lp55xx_predef_pattern board_led_patterns[] = {
172		{
173			.r = mode_1,
174			.size_r = ARRAY_SIZE(mode_1),
175		},
176		{
177			.b = mode_2,
178			.size_b = ARRAY_SIZE(mode_2),
179		},
180	  }
181	
182	  struct lp55xx_platform_data lp5562_pdata = {
183	  ...
184		.patterns      = board_led_patterns,
185		.num_patterns  = ARRAY_SIZE(board_led_patterns),
186	  };
187	
188	Then, mode_1 and mode_2 can be run via through the sysfs.
189	
190	  echo 1 > /sys/bus/i2c/devices/xxxx/led_pattern    # red blinking LED pattern
191	  echo 2 > /sys/bus/i2c/devices/xxxx/led_pattern    # blue LED always on
192	
193	To stop running pattern,
194	  echo 0 > /sys/bus/i2c/devices/xxxx/led_pattern
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