u-boot/doc/README.power-framework

5 # SPDX-License-Identifier:      GPL-2.0+
9 ------------
11 This document describes the second version of the u-boot's PMIC (Power
16 ----------
18 Boards supported by u-boot are getting increasingly complex. Developers and
20 devices are now available on the board - namely power managers (PMIC), fuel
21 gauges (FG), micro USB interface controllers (MUIC), batteries, multi-function
25 -----------------------------------
27 One package can integrate PMIC and MUIC with different addresses on the I2C bus.
28 The same device - e.g. MAX8997 uses two different I2C busses and addresses.
31 different ICs use different endianess. For this reason struct pmic holds
36 one operation - e.g. PMIC enables LDO.
40 to start charging the battery, use PMIC to reduce board's overall power
43 Up till now u-boot doesn't support device model, so a simple one had to be
50 ./drivers/power/pmic/power_{core files}.c
51 e.g. ./drivers/power/pmic/power_core.c
53 ./drivers/power/pmic/<device_function>/<device_function>_<device_name>.c
54 e.g. ./drivers/power/pmic/pmic_max8997.c
58 The framework classifies devices by their function - separate directories should
62 --------------
64 Everything is a power device described by struct pmic. Even battery is
68 - Block diagram of the hierarchy:
69 			-----------------
70 		--------| BAT           |------------
72 		|       -----------------           |
75 	-----------     -----------------       ---------
78 	-----------     -----------------       ---------
83 Definition of the struct pmic is only required with proper name and parameters
84 for communication. This is enough to use the "pmic" command in the u-boot
93 needed (defined at ./include/power/pmic.h):
94 - FG device (struct power_fg):
95 	     -- *fg_battery_check - check if battery is not above its limits
96 	     -- *fg_battery_update - update the pmic framework with current
99 - Charger device (struct power_chrq):
100 	     -- *chrg_type - type/capacity of the charger (including information
102 	     -- *chrg_bat_present - detection if battery to be charged is
104 	     -- *chrg_state - status of the charger - if it is enabled or
107 - Battery device (struct power_battery):
108 	     -- *battery_init - assign proper callbacks to be used by top
110 	     -- *battery_charge - called from "pmic" command, responsible
115 relies on the PMIC/MUIC HW completely (MAX77693).
118 	     -- *fg_battery_check       -> FG device (fg_max17042.c)
119 	     -- *fg_battery_update      -> FG device (fg_max17042.c)
120 	     -- *chrg_type              -> MUIC device (muic_max8997.c)
121 	     -- *chrg_bat_present       -> PMIC device (pmic_max8997.c)
122 	     -- *chrg_state             -> PMIC device (pmic_max8997.c)
123 	     -- *battery_init           -> BAT device (bat_trats.c)
124 	     -- *battery_charge         -> BAT device (bat_trats.c)
126 Also the struct pmic holds method (*low_power_mode) for reducing board's
127 power consumption when one calls "pmic BAT_TRATS bat charge" command.
130 -----------------------------
136 Then "pmic" command supports reading/writing/dump of device's internal
150 TO DO list (for PMICv3) - up till v2014.04
151 ------------------------------------------
154 This is the main problem when a developer tries to build a multi-boot u-boot