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Create sub directory Documentation/leds and add short documentation for LP5521 and LP5523 drivers. Signed-off-by: Samu Onkalo <samu.p.onkalo@nokia.com> Cc: Richard Purdie <rpurdie@rpsys.net> Cc: Jean Delvare <khali@linux-fr.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
84 lines
2.4 KiB
Plaintext
84 lines
2.4 KiB
Plaintext
Kernel driver for lp5523
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========================
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* National Semiconductor LP5523 led driver chip
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* Datasheet: http://www.national.com/pf/LP/LP5523.html
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Authors: Mathias Nyman, Yuri Zaporozhets, Samu Onkalo
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Contact: Samu Onkalo (samu.p.onkalo-at-nokia.com)
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Description
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-----------
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LP5523 can drive up to 9 channels. Leds can be controlled directly via
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the led class control interface. Channels have generic names:
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lp5523:channelx where x is 0...8
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The chip provides 3 engines. Each engine can control channels without
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interaction from the main CPU. Details of the micro engine code can be found
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from the public data sheet. Leds can be muxed to different channels.
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Control interface for the engines:
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x is 1 .. 3
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enginex_mode : disabled, load, run
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enginex_load : microcode load (visible only in load mode)
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enginex_leds : led mux control (visible only in load mode)
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cd /sys/class/leds/lp5523:channel2/device
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echo "load" > engine3_mode
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echo "9d80400004ff05ff437f0000" > engine3_load
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echo "111111111" > engine3_leds
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echo "run" > engine3_mode
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sysfs contains a selftest entry. It measures each channel
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voltage level and checks if it looks reasonable. If the level is too high,
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the led is missing; if the level is too low, there is a short circuit.
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Selftest uses always the current from the platform data.
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Each channel contains led current settings.
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/sys/class/leds/lp5523:channel2/led_current - RW
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/sys/class/leds/lp5523:channel2/max_current - RO
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Format: 10x mA i.e 10 means 1.0 mA
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Example platform data:
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Note - chan_nr can have values between 0 and 8.
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static struct lp5523_led_config lp5523_led_config[] = {
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{
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.chan_nr = 0,
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.led_current = 50,
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.max_current = 130,
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},
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...
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}, {
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.chan_nr = 8,
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.led_current = 50,
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.max_current = 130,
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}
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};
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static int lp5523_setup(void)
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{
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/* Setup HW resources */
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}
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static void lp5523_release(void)
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{
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/* Release HW resources */
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}
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static void lp5523_enable(bool state)
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{
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/* Control chip enable signal */
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}
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static struct lp5523_platform_data lp5523_platform_data = {
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.led_config = lp5523_led_config,
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.num_channels = ARRAY_SIZE(lp5523_led_config),
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.clock_mode = LP5523_CLOCK_EXT,
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.setup_resources = lp5523_setup,
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.release_resources = lp5523_release,
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.enable = lp5523_enable,
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};
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