PMIC hardware components

This message will disappear after all relevant tasks have been resolved.

Semantic MediaWiki

There are 1 incomplete or pending task to finish installation of Semantic MediaWiki. An administrator or user with sufficient rights can complete it. This should be done before adding new data to avoid inconsistencies.

The printable version is no longer supported and may have rendering errors. Please update your browser bookmarks and please use the default browser print function instead.

1 Article purpose[edit source]

The purpose of this article is to:

list the PMIC hardware components that might be integrated in the different boards
link these components to the corresponding software framework(s)
point to the datasheet(s) of these components
explain, when necessary, how to configure these components.

2 Software frameworks[edit source]

Domain	Peripheral	Software frameworks			Comment
Domain	Peripheral	Cortex-A7 secure (OP-TEE)	Cortex-A7 non-secure (Linux)	Cortex-M4 (STM32Cube)	Comment
PMIC	STPMIC1	OP-TEE overview	Regulator overview Watchdog overview U-Boot

3 STPMIC1[edit source]

3.1 Description[edit source]

The STPMIC1 is a device that handles the power supplies for some STM32MP boards. The STPMIC1 main features are:

configuration via I²C bus,
10 regulators of different kinds with over-current protection,
3 power switches for USB supplies,
a power-on key input,
a watchdog,
a thermal protection,
a NORMAL mode and an ALTERNATE mode that is used for system suspend.

The user manual is available here: NOT YET AVAILABLE

3.2 Support in Linux Kernel[edit source]

The STPMIC1 driver is used to handle STPMIC1 Power Management Integrated Circuit (PMIC). The driver is composed of several parts:

The core driver
The regulator driver
The watchdog driver
The input driver

The thermal feature is not supported.

3.2.1 Core driver[edit source]

The core implements the Multi-Function Devices Framework API.

It is probed by the I²C framework.
It handles communication with the PMIC via I²C.
It probes the others STPMIC1 drivers (input, watchdog....).
It acts as an interrupt controller for the other drivers.

Source code:

 include/linux/mfd/stpmic1.h  
 drivers/mfd/stpmic1.c

Bindings are described in:

 Documentation/devicetree/bindings/mfd/st,stpmic1.txt

3.2.2 Regulator driver[edit source]

The driver implements the Regulator framework API

Each BUCK, LDO or POWER SWITCH inside the STPMIC1 device is presented as a voltage regulator.
Power switches are presented as fixed voltage sources. Voltage can not be set.
The driver does not handle the suspend configuration. This is done by the Secure Monitor.

Source code:

 drivers/regulator/stpmic1_regulator.c

Bindings are described in:

 Documentation/devicetree/bindings/regulator/st,stpmic1-regulator.txt

3.2.3 Watchdog driver[edit source]

The driver implements the Watchdog framework API

When enabled, a watchdog device is available for the user-land. As soon as a user has started to write in the watchdog it is armed in the PMIC. When the watchdog timer expires, the PMIC shuts down.

Source code:

 drivers/watchdog/stpmic1_wdt.c

Bindings are described in:

 Documentation/devicetree/bindings/watchdog/st,stpmic1-wdt.txt

3.2.4 Input driver[edit source]

The driver implements the Input framework API.

The driver exposes a single key (KEY_POWER) that can be used as any standard input device in /dev/input/eventX

Source code:

 drivers/input/misc/stpmic1_onkey.c

Bindings are described in:

 Documentation/devicetree/bindings/input/st,stpmic1-onkey.txt

3.2.5 Kernel Configuration[edit source]

With kernel menuconfig, enable following configurations:

core part: MFD_STPMIC1
regulator: REGULATOR_STPMIC1
watchdog: STPMIC1_WATCHDOG
input: INPUT_STPMIC1_ONKEY

3.3 Support in U-BOOT[edit source]

STPMIC1 is used by U-Boot to:

Control regulators used by other drivers (mmc-supply for SDCard for example, usb vbus)
Trace pmic startup reason

STMPIC is supported with existing uclass of the 'Driver Model' described in doc/driver-model/pmic-framework.rst .

pmic :
- uclass: drivers/power/regulator/regulator-uclass.c , CONFIG_DM_PMIC
- driver: drivers/power/pmic/stpmic1.c , CONFIG_PMIC_STPMIC1
regulator:
- uclass: drivers/power/pmic/pmic-uclass.c , CONFIG_DM_REGULATOR
- driver: drivers/power/regulator/stpmic1.c , CONFIG_DM_REGULATOR_STPMIC1
sysreset:
- uclass: drivers/sysreset/sysreset-uclass.c , CONFIG_SYSRESET
- code in pmic driver

The STPMIC1 is available with the existing commands:

pmic (CONFIG_CMD_PMIC)
regulator (CONFIG_CMD_REGULATOR)
poweroff (CONFIG_CMD_POWEROFF)

SPTMIC1 driver supports configuration via device-tree; the bindings, same as kernel, are described in:

 Documentation/devicetree/bindings/regulator/st,stpmic1-regulator.txt

3.4 Support in Cortex-A7 Secure[edit source]

3.4.1 TF-A[edit source]

STPMIC1 is used by TF-A firmware to:

Configure DDR power supplies.
Configure the regulators for system suspend and system shutdown.

Driver source code:

 include/drivers/st/stpmic1.h  
 drivers/st/pmic/stpmic1.c

SPTMIC1 driver supports configuration via device-tree, bindings are described in:

 docs/devicetree/bindings/power/st,stpmic1.txt

An example of PMIC configuration with device tree can be found in this file, node &i2c4:

 fdts/stm32mp15xx-edx.dtsi

When using a PMIC on a board, TF-A is configured to use a secure I²C (I2C4 or I2C6). By default on STMicroelectronics boards, I2C4 is used.

Using another I²C (non-secure) is not supported in the TF-A implementation made by STMicroelectronics. But it is possible to modify the code and device tree files to support it.

Here is an example with I2C2:

Copy the chosen I²C node from Linux device tree in the TF-A device tree file for your board, as well as its dependencies (like pinctrl). You can also remove the properties not used by TF-A as done in the example below

/ {
...
	soc {
	...
 +		i2c2: i2c@40013000 {
 +			compatible = "st,stm32mp15-i2c";
 +			reg = <0x40013000 0x400>;
 +			clocks = <&rcc I2C2_K>;
 +			resets = <&rcc I2C2_R>;
 +			#address-cells = <1>;
 +			#size-cells = <0>;
 +			status = "disabled";
 +		};

change pmic node parent to this newly added I²C

& i2c2 {
	...
	pmic: stpmic@33 {   # You may also require to change this I²C address (33)
	...
};

remove in PMIC node the property:

secure-status = "okay";

Add this I²C base address in plat/st/stm32mp1/stm32mp1_def.h :

#define I2C2_BASE			U(0x40013000)

Add a case for this I²C in register_periph_iomem() function, in the file plat/st/stm32mp1/stm32mp1_shared_resources.c . It should be placed with the other non-secure peripherals (UARTs and IWDG2):

	case UART7_BASE:
	case UART8_BASE:
	case IWDG2_BASE:
+	case I2C2_BASE:
		/* Allow drivers to register some non secure resources */
		VERBOSE("IO for non secure resource 0x%x\n",
			(unsigned int)base);

Add the clock of this I²C in the stm32mp1_clk_gate[] table in the file drivers/st/clk/stm32mp1_clk.c

+	_CLK_SC_SELEC(RCC_MP_APB1ENSETR, 22, I2C2_K, _I2C12_SEL),

Regarding the GPIO ports used by I2C2: in this stm32mp1_clk_gate[] table, remove the #ifdef IMAGE_BL2 around GPIO banks entries if present

3.4.2 OP-TEE[edit source]

STPMIC1 is used by OP-TEE OS to configure the regulators for system suspend and system shutdown.

Driver source code:

 core/include/drivers/stpmic1.h  
 core/drivers/stpmic1.c