Texas Instruments TPS6594 PFSM driver

Author: Julien Panis (jpanis@baylibre.com)

Overview

Strictly speaking, PFSM (Pre-configurable Finite State Machine) is not hardware. It is a piece of code.

The TPS6594 PMIC (Power Management IC) integrates a state machine which manages operational modes. Depending on the current operational mode, some voltage domains remain energized while others can be off.

The PFSM driver can be used to trigger transitions between configured states. It also provides R/W access to the device registers.

Supported chips

  • tps6594-q1

  • tps6593-q1

  • lp8764-q1

Driver location

drivers/misc/tps6594-pfsm.c

Driver type definitions

include/uapi/linux/tps6594_pfsm.h

Driver IOCTLs

:c:macro::PMIC_GOTO_STANDBY All device resources are powered down. The processor is off, and no voltage domains are energized.

:c:macro::PMIC_GOTO_LP_STANDBY The digital and analog functions of the PMIC, which are not required to be always-on, are turned off (low-power).

:c:macro::PMIC_UPDATE_PGM Triggers a firmware update.

:c:macro::PMIC_SET_ACTIVE_STATE One of the operational modes. The PMICs are fully functional and supply power to all PDN loads. All voltage domains are energized in both MCU and Main processor sections.

:c:macro::PMIC_SET_MCU_ONLY_STATE One of the operational modes. Only the power resources assigned to the MCU Safety Island are on.

:c:macro::PMIC_SET_RETENTION_STATE One of the operational modes. Depending on the triggers set, some DDR/GPIO voltage domains can remain energized, while all other domains are off to minimize total system power.

Driver usage

See available PFSMs:

# ls /dev/pfsm*

Dump the registers of pages 0 and 1:

# hexdump -C /dev/pfsm-0-0x48

See PFSM events:

# cat /proc/interrupts

Userspace code example

samples/pfsm/pfsm-wakeup.c