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Diffstat (limited to 'kernel/Documentation/leds/leds-lp5521.txt')
| -rw-r--r-- | kernel/Documentation/leds/leds-lp5521.txt | 101 |
1 files changed, 101 insertions, 0 deletions
diff --git a/kernel/Documentation/leds/leds-lp5521.txt b/kernel/Documentation/leds/leds-lp5521.txt new file mode 100644 index 000000000..d08d8c179 --- /dev/null +++ b/kernel/Documentation/leds/leds-lp5521.txt @@ -0,0 +1,101 @@ +Kernel driver for lp5521 +======================== + +* National Semiconductor LP5521 led driver chip +* Datasheet: http://www.national.com/pf/LP/LP5521.html + +Authors: Mathias Nyman, Yuri Zaporozhets, Samu Onkalo +Contact: Samu Onkalo (samu.p.onkalo-at-nokia.com) + +Description +----------- + +LP5521 can drive up to 3 channels. Leds can be controlled directly via +the led class control interface. Channels have generic names: +lp5521:channelx, where x is 0 .. 2 + +All three channels can be also controlled using the engine micro programs. +More details of the instructions can be found from the public data sheet. + +LP5521 has the internal program memory for running various LED patterns. +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 +the clock mode is automatically set to the requested one. + +Each channel has its own led current settings. +/sys/class/leds/lp5521:channel0/led_current - RW +/sys/class/leds/lp5521:channel0/max_current - RO +Format: 10x mA i.e 10 means 1.0 mA + +example platform data: + +Note: chan_nr can have values between 0 and 2. +The name of each channel can be configurable. +If the name field is not defined, the default name will be set to 'xxxx:channelN' +(XXXX : pdata->label or i2c client name, N : channel number) + +static struct lp55xx_led_config lp5521_led_config[] = { + { + .name = "red", + .chan_nr = 0, + .led_current = 50, + .max_current = 130, + }, { + .name = "green", + .chan_nr = 1, + .led_current = 0, + .max_current = 130, + }, { + .name = "blue", + .chan_nr = 2, + .led_current = 0, + .max_current = 130, + } +}; + +static int lp5521_setup(void) +{ + /* setup HW resources */ +} + +static void lp5521_release(void) +{ + /* Release HW resources */ +} + +static void lp5521_enable(bool state) +{ + /* Control of chip enable signal */ +} + +static struct lp55xx_platform_data lp5521_platform_data = { + .led_config = lp5521_led_config, + .num_channels = ARRAY_SIZE(lp5521_led_config), + .clock_mode = LP55XX_CLOCK_EXT, + .setup_resources = lp5521_setup, + .release_resources = lp5521_release, + .enable = lp5521_enable, +}; + +If the current is set to 0 in the platform data, that channel is +disabled and it is not visible in the sysfs. |