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 | ||
|---|---|---|---|---|---|
| Cortex-A7 secure (OP-TEE) |
Cortex-A7 non-secure (Linux) |
Cortex-M4 (STM32Cube) | |||
| 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
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