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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>
89 lines
2.4 KiB
Plaintext
89 lines
2.4 KiB
Plaintext
Kernel driver for lp5521
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========================
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* National Semiconductor LP5521 led driver chip
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* Datasheet: http://www.national.com/pf/LP/LP5521.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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LP5521 can drive up to 3 channels. Leds can be controlled directly via
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the led class control interface. Channels have generic names:
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lp5521:channelx, where x is 0 .. 2
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All three channels can be also controlled using the engine micro programs.
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More details of the instructions can be found from the public data sheet.
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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 : store program (visible only in engine load mode)
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Example (start to blink the channel 2 led):
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cd /sys/class/leds/lp5521:channel2/device
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echo "load" > engine3_mode
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echo "037f4d0003ff6000" > engine3_load
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echo "run" > engine3_mode
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stop the engine:
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echo "disabled" > engine3_mode
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sysfs contains a selftest entry.
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The test communicates with the chip and checks that
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the clock mode is automatically set to the requested one.
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Each channel has its own led current settings.
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/sys/class/leds/lp5521:channel0/led_current - RW
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/sys/class/leds/lp5521:channel0/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 2.
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static struct lp5521_led_config lp5521_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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.chan_nr = 1,
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.led_current = 0,
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.max_current = 130,
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}, {
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.chan_nr = 2,
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.led_current = 0,
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.max_current = 130,
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}
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};
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static int lp5521_setup(void)
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{
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/* setup HW resources */
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}
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static void lp5521_release(void)
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{
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/* Release HW resources */
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}
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static void lp5521_enable(bool state)
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{
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/* Control of chip enable signal */
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}
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static struct lp5521_platform_data lp5521_platform_data = {
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.led_config = lp5521_led_config,
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.num_channels = ARRAY_SIZE(lp5521_led_config),
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.clock_mode = LP5521_CLOCK_EXT,
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.setup_resources = lp5521_setup,
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.release_resources = lp5521_release,
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.enable = lp5521_enable,
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};
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If the current is set to 0 in the platform data, that channel is
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disabled and it is not visible in the sysfs.
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