1 What: /sys/bus/i2c/devices/.../bd957 1 What: /sys/bus/i2c/devices/.../bd9571mwv-regulator.*.auto/backup_mode
2 Date: Jul 2018 2 Date: Jul 2018
3 KernelVersion: 4.19 3 KernelVersion: 4.19
4 Contact: Geert Uytterhoeven <geert+renes 4 Contact: Geert Uytterhoeven <geert+renesas@glider.be>
5 Description: Read/write the current state o 5 Description: Read/write the current state of DDR Backup Mode, which controls
6 if DDR power rails will be kep 6 if DDR power rails will be kept powered during system suspend.
7 ("on"/"1" = enabled, "off"/"0" 7 ("on"/"1" = enabled, "off"/"0" = disabled).
8 Two types of power switches (o 8 Two types of power switches (or control signals) can be used:
9 9
10 A. With a momentary power sw 10 A. With a momentary power switch (or pulse signal), DDR
11 Backup Mode is enabled by 11 Backup Mode is enabled by default when available, as the
12 PMIC will be configured o 12 PMIC will be configured only during system suspend.
13 B. With a toggle power switc 13 B. With a toggle power switch (or level signal), the
14 following steps must be f 14 following steps must be followed exactly:
15 15
16 1. Configure PMIC for b 16 1. Configure PMIC for backup mode, to change the role of
17 the accessory power 17 the accessory power switch from a power switch to a
18 wake-up switch, 18 wake-up switch,
19 2. Switch accessory pow 19 2. Switch accessory power switch off, to prepare for
20 system suspend, whic 20 system suspend, which is a manual step not controlled
21 by software, 21 by software,
22 3. Suspend system, 22 3. Suspend system,
23 4. Switch accessory pow 23 4. Switch accessory power switch on, to resume the
24 system. 24 system.
25 25
26 DDR Backup Mode must be e 26 DDR Backup Mode must be explicitly enabled by the user,
27 to invoke step 1. 27 to invoke step 1.
28 28
29 See also Documentation/devicet 29 See also Documentation/devicetree/bindings/mfd/rohm,bd9571mwv.yaml.
30 Users: User space applications for em 30 Users: User space applications for embedded boards equipped with a
31 BD9571MWV PMIC. 31 BD9571MWV PMIC.
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.