doc/driver-model/pmic-framework.txt

2 # (C) Copyright 2014-2015 Samsung Electronics
5 # SPDX-License-Identifier:      GPL-2.0+
8 PMIC framework based on Driver Model
13 3. Pmic uclass
18 This is an introduction to driver-model multi uclass PMIC IC's support.
20 - UCLASS_PMIC      - basic uclass type for PMIC I/O, which provides common
22 - UCLASS_REGULATOR - additional uclass type for specific PMIC features,
27 - drivers/power/pmic/pmic-uclass.c
28 - include/power/pmic.h
30 - drivers/power/regulator/regulator-uclass.c
31 - include/power/regulator.h
34 - common/cmd_pmic.c
35 - common/cmd_regulator.c
39 The Power Management Integrated Circuits (PMIC) are used in embedded systems
40 to provide stable, precise and specific voltage power source with over-voltage
43 The single PMIC can provide various functions by single or multiple interfaces,
46 -- SoC
49  | BUS 0     |       Multi interface PMIC IC        |--> LDO out 1
50  | e.g.I2C0  |                                      |--> LDO out N
51  |-----------|---- PMIC device 0 (READ/WRITE ops)   |
52  | or SPI0   |    |_ REGULATOR device (ldo/... ops) |--> BUCK out 1
53  |           |    |_ CHARGER device (charger ops)   |--> BUCK out M
55  | BUS 1     |    |_ ...                            |---> BATTERY
57  |-----------|---- PMIC device 1 (READ/WRITE ops)   |---> USB in 1
58  . or SPI1   |    |_ RTC device (rtc ops)           |---> USB in 2
59  .           |______________________________________|---> USB out
62 Since U-Boot provides driver model features for I2C and SPI bus drivers,
63 the PMIC devices should also support this. By the pmic and regulator API's,
64 PMIC drivers can simply provide a common functions, for multi-interface and
65 and multi-instance device support.
69 - Common I/O API - UCLASS_PMIC
70 For the multi-function PMIC devices, this can be used as parent I/O device
73 - Common regulator API - UCLASS_REGULATOR
75 interface, based on kernel-style regulator device tree constraints.
78 use pmic read/write directly.
80 3. Pmic uclass
84 * Header:   'include/power/pmic.h'
85 * Core:     'drivers/power/pmic/pmic-uclass.c'
89 * Example:  'drivers/power/pmic/max77686.c'
93 As an example of the pmic driver, please refer to the MAX77686 driver.
99 The 'pmic; command also supports the new API. So the pmic command can be enabled
101 The new pmic command allows to:
102 - list pmic devices
103 - choose the current device (like the mmc command)
104 - read or write the pmic register
105 - dump all pmic registers
108 for pmic I/O operations only.
117 * Core:    'drivers/power/regulator/regulator-uclass.c'
119   binding: 'doc/device-tree-bindings/regulator/regulator.txt'
123            'drivers/power/pmic/max77686.c' (required I/O driver for the above)
130 but this driver can't operate without pmic's example driver, which provides an
136 - list regulator devices
137 - choose the current device (like the mmc command)
138 - do all regulator-specific operations