0001 What: /sys/bus/i2c/devices/.../bd9571mwv-regulator.*.auto/backup_mode
0002 Date: Jul 2018
0003 KernelVersion: 4.19
0004 Contact: Geert Uytterhoeven <geert+renesas@glider.be>
0005 Description: Read/write the current state of DDR Backup Mode, which controls
0006 if DDR power rails will be kept powered during system suspend.
0007 ("on"/"1" = enabled, "off"/"0" = disabled).
0008 Two types of power switches (or control signals) can be used:
0009
0010 A. With a momentary power switch (or pulse signal), DDR
0011 Backup Mode is enabled by default when available, as the
0012 PMIC will be configured only during system suspend.
0013 B. With a toggle power switch (or level signal), the
0014 following steps must be followed exactly:
0015
0016 1. Configure PMIC for backup mode, to change the role of
0017 the accessory power switch from a power switch to a
0018 wake-up switch,
0019 2. Switch accessory power switch off, to prepare for
0020 system suspend, which is a manual step not controlled
0021 by software,
0022 3. Suspend system,
0023 4. Switch accessory power switch on, to resume the
0024 system.
0025
0026 DDR Backup Mode must be explicitly enabled by the user,
0027 to invoke step 1.
0028
0029 See also Documentation/devicetree/bindings/mfd/rohm,bd9571mwv.yaml.
0030 Users: User space applications for embedded boards equipped with a
0031 BD9571MWV PMIC.
