leds-lp5521.txt 2.39 KB
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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.

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LP5521 has the internal program memory for running various LED patterns.
For the details, please refer to 'firmware' section in leds-lp55xx.txt
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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.
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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)
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static struct lp55xx_led_config lp5521_led_config[] = {
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        {
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		.name = "red",
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                .chan_nr        = 0,
                .led_current    = 50,
		.max_current    = 130,
        }, {
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		.name = "green",
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                .chan_nr        = 1,
                .led_current    = 0,
		.max_current    = 130,
        }, {
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		.name = "blue",
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                .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 */
}

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static struct lp55xx_platform_data lp5521_platform_data = {
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        .led_config     = lp5521_led_config,
        .num_channels   = ARRAY_SIZE(lp5521_led_config),
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        .clock_mode     = LP55XX_CLOCK_EXT,
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        .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.