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.
  46
  47static struct lp5521_led_config lp5521_led_config[] = {
  48        {
  49                .chan_nr        = 0,
  50                .led_current    = 50,
  51                .max_current    = 130,
  52        }, {
  53                .chan_nr        = 1,
  54                .led_current    = 0,
  55                .max_current    = 130,
  56        }, {
  57                .chan_nr        = 2,
  58                .led_current    = 0,
  59                .max_current    = 130,
  60        }
  61};
  62
  63static int lp5521_setup(void)
  64{
  65        /* setup HW resources */
  66}
  67
  68static void lp5521_release(void)
  69{
  70        /* Release HW resources */
  71}
  72
  73static void lp5521_enable(bool state)
  74{
  75        /* Control of chip enable signal */
  76}
  77
  78static struct lp5521_platform_data lp5521_platform_data = {
  79        .led_config     = lp5521_led_config,
  80        .num_channels   = ARRAY_SIZE(lp5521_led_config),
  81        .clock_mode     = LP5521_CLOCK_EXT,
  82        .setup_resources   = lp5521_setup,
  83        .release_resources = lp5521_release,
  84        .enable            = lp5521_enable,
  85};
  86
  87If the current is set to 0 in the platform data, that channel is
  88disabled and it is not visible in the sysfs.
  89
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