linux/Documentation/leds/leds-lp5521.txt
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   1Kernel driver for lp5521
   2========================
   3
   4* National Semiconductor LP5521 led driver chip
   5* Datasheet: http://www.national.com/pf/LP/LP5521.html
   6
   7Authors: Mathias Nyman, Yuri Zaporozhets, Samu Onkalo
   8Contact: Samu Onkalo (samu.p.onkalo-at-nokia.com)
   9
  10Description
  11-----------
  12
  13LP5521 can drive up to 3 channels. Leds can be controlled directly via
  14the led class control interface. Channels have generic names:
  15lp5521:channelx, where x is 0 .. 2
  16
  17All three channels can be also controlled using the engine micro programs.
  18More details of the instructions can be found from the public data sheet.
  19
  20Control interface for the engines:
  21x is 1 .. 3
  22enginex_mode : disabled, load, run
  23enginex_load : store program (visible only in engine load mode)
  24
  25Example (start to blink the channel 2 led):
  26cd   /sys/class/leds/lp5521:channel2/device
  27echo "load" > engine3_mode
  28echo "037f4d0003ff6000" > engine3_load
  29echo "run" > engine3_mode
  30
  31stop the engine:
  32echo "disabled" > engine3_mode
  33
  34sysfs contains a selftest entry.
  35The test communicates with the chip and checks that
  36the clock mode is automatically set to the requested one.
  37
  38Each channel has its own led current settings.
  39/sys/class/leds/lp5521:channel0/led_current - RW
  40/sys/class/leds/lp5521:channel0/max_current - RO
  41Format: 10x mA i.e 10 means 1.0 mA
  42
  43example platform data:
  44
  45Note: chan_nr can have values between 0 and 2.
  46The name of each channel can be configurable.
  47If the name field is not defined, the default name will be set to 'xxxx:channelN'
  48(XXXX : pdata->label or i2c client name, N : channel number)
  49
  50static struct lp5521_led_config lp5521_led_config[] = {
  51        {
  52                .name = "red",
  53                .chan_nr        = 0,
  54                .led_current    = 50,
  55                .max_current    = 130,
  56        }, {
  57                .name = "green",
  58                .chan_nr        = 1,
  59                .led_current    = 0,
  60                .max_current    = 130,
  61        }, {
  62                .name = "blue",
  63                .chan_nr        = 2,
  64                .led_current    = 0,
  65                .max_current    = 130,
  66        }
  67};
  68
  69static int lp5521_setup(void)
  70{
  71        /* setup HW resources */
  72}
  73
  74static void lp5521_release(void)
  75{
  76        /* Release HW resources */
  77}
  78
  79static void lp5521_enable(bool state)
  80{
  81        /* Control of chip enable signal */
  82}
  83
  84static struct lp5521_platform_data lp5521_platform_data = {
  85        .led_config     = lp5521_led_config,
  86        .num_channels   = ARRAY_SIZE(lp5521_led_config),
  87        .clock_mode     = LP5521_CLOCK_EXT,
  88        .setup_resources   = lp5521_setup,
  89        .release_resources = lp5521_release,
  90        .enable            = lp5521_enable,
  91};
  92
  93If the current is set to 0 in the platform data, that channel is
  94disabled and it is not visible in the sysfs.
  95
  96The 'update_config' : CONFIG register (ADDR 08h)
  97This value is platform-specific data.
  98If update_config is not defined, the CONFIG register is set with
  99'LP5521_PWRSAVE_EN | LP5521_CP_MODE_AUTO | LP5521_R_TO_BATT'.
 100(Enable auto-powersave, set charge pump to auto, red to battery)
 101
 102example of update_config :
 103
 104#define LP5521_CONFIGS  (LP5521_PWM_HF | LP5521_PWRSAVE_EN | \
 105                        LP5521_CP_MODE_AUTO | LP5521_R_TO_BATT | \
 106                        LP5521_CLK_INT)
 107
 108static struct lp5521_platform_data lp5521_pdata = {
 109        .led_config = lp5521_led_config,
 110        .num_channels = ARRAY_SIZE(lp5521_led_config),
 111        .clock_mode = LP5521_CLOCK_INT,
 112        .update_config = LP5521_CONFIGS,
 113};
 114
 115LED patterns : LP5521 has autonomous operation without external control.
 116Pattern data can be defined in the platform data.
 117
 118example of led pattern data :
 119
 120/* RGB(50,5,0) 500ms on, 500ms off, infinite loop */
 121static u8 pattern_red[] = {
 122                0x40, 0x32, 0x60, 0x00, 0x40, 0x00, 0x60, 0x00,
 123                };
 124
 125static u8 pattern_green[] = {
 126                0x40, 0x05, 0x60, 0x00, 0x40, 0x00, 0x60, 0x00,
 127                };
 128
 129static struct lp5521_led_pattern board_led_patterns[] = {
 130        {
 131                .r = pattern_red,
 132                .g = pattern_green,
 133                .size_r = ARRAY_SIZE(pattern_red),
 134                .size_g = ARRAY_SIZE(pattern_green),
 135        },
 136};
 137
 138static struct lp5521_platform_data lp5521_platform_data = {
 139        .led_config     = lp5521_led_config,
 140        .num_channels   = ARRAY_SIZE(lp5521_led_config),
 141        .clock_mode     = LP5521_CLOCK_EXT,
 142        .patterns = board_led_patterns,
 143        .num_patterns = ARRAY_SIZE(board_led_patterns),
 144};
 145
 146Then predefined led pattern(s) can be executed via the sysfs.
 147To start the pattern #1,
 148# echo 1 > /sys/bus/i2c/devices/xxxx/led_pattern
 149(xxxx : i2c bus & slave address)
 150To end the pattern,
 151# echo 0 > /sys/bus/i2c/devices/xxxx/led_pattern
 152
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