From fdea8bbbc8a3e2ea17ebad507957039ef94a4414 Mon Sep 17 00:00:00 2001 From: Przemyslaw Marczak Date: Mon, 20 Apr 2015 20:07:49 +0200 Subject: doc: driver-model: pmic and regulator uclass documentation Since this framework is still under the construction, the main documentation is kept in the header files. Signed-off-by: Przemyslaw Marczak Acked-by: Simon Glass --- doc/driver-model/pmic-framework.txt | 142 ++++++++++++++++++++++++++++++++++++ 1 file changed, 142 insertions(+) create mode 100644 doc/driver-model/pmic-framework.txt diff --git a/doc/driver-model/pmic-framework.txt b/doc/driver-model/pmic-framework.txt new file mode 100644 index 0000000..cc82236 --- /dev/null +++ b/doc/driver-model/pmic-framework.txt @@ -0,0 +1,142 @@ +# +# (C) Copyright 2014-2015 Samsung Electronics +# Przemyslaw Marczak +# +# SPDX-License-Identifier: GPL-2.0+ +# + +PMIC framework based on Driver Model +==================================== +TOC: +1. Introduction +2. How does it work +3. Pmic uclass +4. Regulator uclass + +1. Introduction +=============== +This is an introduction to driver-model multi uclass PMIC IC's support. +At present it's based on two uclass types: +- UCLASS_PMIC - basic uclass type for PMIC I/O, which provides common + read/write interface. +- UCLASS_REGULATOR - additional uclass type for specific PMIC features, + which are Voltage/Current regulators. + +New files: +UCLASS_PMIC: +- drivers/power/pmic/pmic-uclass.c +- include/power/pmic.h +UCLASS_REGULATOR: +- drivers/power/regulator/regulator-uclass.c +- include/power/regulator.h + +Commands: +- common/cmd_pmic.c +- common/cmd_regulator.c + +2. How doees it work +==================== +The Power Management Integrated Circuits (PMIC) are used in embedded systems +to provide stable, precise and specific voltage power source with over-voltage +and thermal protection circuits. + +The single PMIC can provide various functions by single or multiple interfaces, +like in the example below. + +-- SoC + | + | ______________________________________ + | BUS 0 | Multi interface PMIC IC |--> LDO out 1 + | e.g.I2C0 | |--> LDO out N + |-----------|---- PMIC device 0 (READ/WRITE ops) | + | or SPI0 | |_ REGULATOR device (ldo/... ops) |--> BUCK out 1 + | | |_ CHARGER device (charger ops) |--> BUCK out M + | | |_ MUIC device (microUSB con ops) | + | BUS 1 | |_ ... |---> BATTERY + | e.g.I2C1 | | + |-----------|---- PMIC device 1 (READ/WRITE ops) |---> USB in 1 + . or SPI1 | |_ RTC device (rtc ops) |---> USB in 2 + . |______________________________________|---> USB out + . + +Since U-Boot provides driver model features for I2C and SPI bus drivers, +the PMIC devices should also support this. By the pmic and regulator API's, +PMIC drivers can simply provide a common functions, for multi-interface and +and multi-instance device support. + +Basic design assumptions: + +- Common I/O API - UCLASS_PMIC +For the multi-function PMIC devices, this can be used as parent I/O device +for each IC's interface. Then, each children uses the same dev for read/write. + +- Common regulator API - UCLASS_REGULATOR +For driving the regulator attributes, auto setting function or command line +interface, based on kernel-style regulator device tree constraints. + +For simple implementations, regulator drivers are not required, so the code can +use pmic read/write directly. + +3. Pmic uclass +============== +The basic informations: +* Uclass: 'UCLASS_PMIC' +* Header: 'include/power/pmic.h' +* Core: 'drivers/power/pmic/pmic-uclass.c' + config: 'CONFIG_DM_PMIC' +* Command: 'common/cmd_pmic.c' + config: 'CONFIG_CMD_PMIC' +* Example: 'drivers/power/pmic/max77686.c' + +This is still under the construction. So for the API description, please refer +to the header file. + +As an example of the pmic driver, please refer to the MAX77686 driver. + +Please pay attention for the driver's '.bind' method. Exactly the function call: +'pmic_bind_childs()', which is used to bind the regulators by using the array of +regulator's node, compatible prefixes. + +The 'pmic; command also supports the new API. So the pmic command can be enabled +by adding CONFIG_CMD_PMIC. +The new pmic command allows to: +- list pmic devices +- choose the current device (like the mmc command) +- read or write the pmic register +- dump all pmic registers + +This command can use only UCLASS_PMIC devices, since this uclass is designed +for pmic I/O operations only. + +For more informations, please refer to the file: 'common/cmd_pmic.c'. + +4. Regulator uclass +=================== +The basic informations: +* Uclass: 'UCLASS_REGULATOR' +* Header: 'include/power/regulator.h' +* Core: 'drivers/power/regulator/regulator-uclass.c' + config: 'CONFIG_DM_REGULATOR' + binding: 'doc/device-tree-bindings/regulator/regulator.txt' +* Command: 'common/cmd_regulator.c' + config: 'CONFIG_CMD_REGULATOR' +* Example: 'drivers/power/regulator/max77686.c' + 'drivers/power/pmic/max77686.c' (required I/O driver for the above) +* Example: 'drivers/power/regulator/fixed.c' + config" 'CONFIG_DM_REGULATOR_FIXED' + +This is still under the construction. So for the API description, please refer +to the header file. + +For the example regulator driver, please refer to the MAX77686 regulator driver, +but this driver can't operate without pmic's example driver, which provides an +I/O interface for MAX77686 regulator. + +The second example is a fixed Voltage/Current regulator for a common use. + +The 'regulator' command also supports the new API. The command allow: +- list regulator devices +- choose the current device (like the mmc command) +- do all regulator-specific operations + +For more informations, please refer to the file: 'common/cmd_regulator.c' -- cgit v1.1