Implement LED boot API to signal correct boot of the system.
led_boot_on/off/blink() are introduced to turn ON, OFF and BLINK the
designated boot LED.
New Kconfig is introduced, CONFIG_LED_BOOT to enable the feature.
This makes use of the /options/u-boot property "boot-led" to the
define the boot LED.
It's also introduced a new /options/u-boot property "boot-led-period"
to define the default period when the LED is set to blink mode.
If "boot-led-period" is not defined, the value of 250 (ms) is
used by default.
If CONFIG_LED_BLINK or CONFIG_LED_SW_BLINK is not enabled,
led_boot_blink call will fallback to simple LED ON.
To cache the data we repurpose the now unused led_uc_priv for storage of
global LED uclass info.
Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
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