MFC r277042:

Add support to turn off Beaglebone with poweroff(8) or shutdown(8) -p.

To cut off the power we need to start the shutdown sequence by writing
the OFF bit on PMIC.

Once the PMIC is programmed the SoC needs to toggle the PMIC_PWR_ENABLE
pin when it is ready for the PMIC to cut off the power. This is done by
triggering the ALARM2 interrupt on SoC RTC.

The RTC driver only works in power management mode which means it won't
provide any kind of time keeping functionality. It only implements a way
to trigger the ALARM2 interrupt when requested.

Adds the ADC driver for TI AM3xxx SoC family.

The ADC has a 12bit resolution and its raw output can be read via sysctl(8)
interface.

The driver allows the setup of ADC clock, samples average and open delay
(the number of clock cycles to wait before start the conversion).

The TSC_ADC module is set in the general purpose mode (no touchscreen
support).

Tested on Beaglebone-black.

Written based on AM335x TRM.

MFC r277042:

Add support to turn off Beaglebone with poweroff(8) or shutdown(8) -p.

To cut off the power we need to start the shutdown sequence by writing
the OFF bit on PMIC.

Once the PMIC is programmed the SoC needs to toggle the PMIC_PWR_ENABLE
pin when it is ready for the PMIC to cut off the power. This is done by
triggering the ALARM2 interrupt on SoC RTC.

The RTC driver only works in power management mode which means it won't
provide any kind of time keeping functionality. It only implements a way
to trigger the ALARM2 interrupt when requested.

Adds the ADC driver for TI AM3xxx SoC family.

The ADC has a 12bit resolution and its raw output can be read via sysctl(8)
interface.

The driver allows the setup of ADC clock, samples average and open delay
(the number of clock cycles to wait before start the conversion).

The TSC_ADC module is set in the general purpose mode (no touchscreen
support).

Tested on Beaglebone-black.

Written based on AM335x TRM.