linux-next/Documentation/leds/leds-lp5521.txt

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.

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

stop the engine:
echo "disabled" > engine3_mode

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 lp5521_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 lp5521_platform_data lp5521_platform_data = {
        .led_config     = lp5521_led_config,
        .num_channels   = ARRAY_SIZE(lp5521_led_config),
        .clock_mode     = LP5521_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.

The 'update_config' : CONFIG register (ADDR 08h)
This value is platform-specific data.
If update_config is not defined, the CONFIG register is set with
'LP5521_PWRSAVE_EN | LP5521_CP_MODE_AUTO | LP5521_R_TO_BATT'.
(Enable auto-powersave, set charge pump to auto, red to battery)

example of update_config :

#define LP5521_CONFIGS	(LP5521_PWM_HF | LP5521_PWRSAVE_EN | \
			LP5521_CP_MODE_AUTO | LP5521_R_TO_BATT | \
			LP5521_CLK_INT)

static struct lp5521_platform_data lp5521_pdata = {
	.led_config = lp5521_led_config,
	.num_channels = ARRAY_SIZE(lp5521_led_config),
	.clock_mode = LP5521_CLOCK_INT,
	.update_config = LP5521_CONFIGS,
};

LED patterns : LP5521 has autonomous operation without external control.
Pattern data can be defined in the platform data.

example of led pattern data :

/* RGB(50,5,0) 500ms on, 500ms off, infinite loop */
static u8 pattern_red[] = {
		0x40, 0x32, 0x60, 0x00,	0x40, 0x00, 0x60, 0x00,
		};

static u8 pattern_green[] = {
		0x40, 0x05, 0x60, 0x00, 0x40, 0x00, 0x60, 0x00,
		};

static struct lp5521_led_pattern board_led_patterns[] = {
	{
		.r = pattern_red,
		.g = pattern_green,
		.size_r = ARRAY_SIZE(pattern_red),
		.size_g = ARRAY_SIZE(pattern_green),
	},
};

static struct lp5521_platform_data lp5521_platform_data = {
        .led_config     = lp5521_led_config,
        .num_channels   = ARRAY_SIZE(lp5521_led_config),
        .clock_mode     = LP5521_CLOCK_EXT,
	.patterns = board_led_patterns,
	.num_patterns = ARRAY_SIZE(board_led_patterns),
};

Then predefined led pattern(s) can be executed via the sysfs.
To start the pattern #1,
# echo 1 > /sys/bus/i2c/devices/xxxx/led_pattern
(xxxx : i2c bus & slave address)
To end the pattern,
# echo 0 > /sys/bus/i2c/devices/xxxx/led_pattern