This is an RFC and meant to get feedback from other developers as
- the specification (pinctrl part) is still in a draft
- the upstream patch for linux, including dt bindings, is still WIP
- I'm not confident the drivers are generic enough to cover most HWs
- The tests ("ut") doesn't cover all the features yetThis patch series allows users to access SCMI pin control protocol provided by SCMI server (platform). See SCMI specification document v3.2 beta 2[1] for more details about SCMI pin control protocol. The implementation consists of two layers: - basic helper functions for SCMI pin control protocol in drivers/firmware/scmi/pinctrl.c (patch#2) - DM-compliant pinctrl/gpio drivers, which utilizes the helper functions, in drivers/pinctrl/pinctrl-scmi.c (patch#3,#4) [1] https://developer.arm.com/documentation/den0056/e/?lang=en DT bindings =========== Upstream pinctrl patch for linux defines the bindings in [2] though it doesn't say much. I expect that my implementation basically complies with U-Boot's generic bindings described in [3], but not all the features are verified. As for gpio, unless you hard-code pin assignments directly in a device driver, my implementation allows the following alternatives in DT. Either way, we may need an additional binding description for gpio. (A) scmi { ... // other protocols scmi_pinctrl: protocol@19 { // Pin control protocol ... {pinmux definitions}... // if any, including GPIO? } } scmi_gpio: scmi_gpio { compatible = "arm,scmi-gpio-generic"; gpio-controller; #gpio-cells = <2>; gpio-ranges = <&scmi_pinctrl 0 5 4>, <&scmi_pinctrl 4 0 0>; gpio-ranges-group-names = "", "ANOTHER_GPIO_GROUP"; } some_device { ... reset-gpios = <&scmi_gpio 0 GPIO_ACTIVE_HIGH>; } (B) scmi { ... // other protocols scmi_pinctrl: protocol@19 { // Pin control protocol ... {pinmux definitions}... // if any, including GPIO? scmi_gpio: scmi_gpio { // no need for "compatible" gpio-controller; #gpio-cells = <2>; gpio-ranges = <&scmi_pinctrl 0 5 4>, <&scmi_pinctrl 4 0 0>; gpio-ranges-group-names = "", "ANOTHER_GPIO_GROUP"; } } } some_device { ... reset-gpios = <&scmi_gpio 0 GPIO_ACTIVE_HIGH>; } (C) if "gpio-ranges" is missing in gpio definition, assume 1:1 mapping, i.e. use a native pinctrl pin number (5). some_device { ... reset-gpios = <&scmi_gpio 5 GPIO_ACTIVE_HIGH>; } [2] https://lkml.iu.edu/hypermail/linux/kernel/2308.1/01084.html [3] <u-boot>/doc/device-tree-bindings/pinctrl/pinctrl-bindings.txt <u-boot>/doc/device-tree-bindings/gpio/gpio.txt Test ==== The patch series was tested on the following platforms: * sandbox ("ut dm pinmux" and manually using gpio command) Prerequisite: ============= * This patch series is based on my WIP "Base protocol support" patches on v2023.10-rc3. You can fetch the whole code from [4]. [4] https://git.linaro.org/people/takahiro.akashi/u-boot.git branch:scmi/pinctrl Patches: ======== Patch#1: Add SCMI base protocol driver Patch#2-#4: Add drivers Patch#5-#6: Test related Change history: =============== RFC (Sep 6, 2023) * initial release as RFC AKASHI Takahiro (6): firmware: scmi: fix protocol enumeration logic firmware: scmi: add pinctrl protocol support pinctrl: add scmi driver gpio: add scmi driver based on pinctrl firmware: scmi: add pseudo pinctrl protocol support on sandbox test: dm: add SCMI pinctrl test arch/sandbox/dts/test.dts | 115 +++ cmd/scmi.c | 1 + drivers/firmware/scmi/Kconfig | 3 + drivers/firmware/scmi/Makefile | 1 + drivers/firmware/scmi/pinctrl.c | 412 ++++++++ drivers/firmware/scmi/sandbox-scmi_agent.c | 722 +++++++++++++ drivers/firmware/scmi/scmi_agent-uclass.c | 18 +- drivers/pinctrl/Kconfig | 11 + drivers/pinctrl/Makefile | 1 + drivers/pinctrl/pinctrl-scmi.c | 1071 ++++++++++++++++++++ include/scmi_agent-uclass.h | 2 + include/scmi_protocols.h | 435 ++++++++ test/dm/scmi.c | 62 ++ 13 files changed, 2852 insertions(+), 2 deletions(-) create mode 100644 drivers/firmware/scmi/pinctrl.c create mode 100644 drivers/pinctrl/pinctrl-scmi.c -- 2.34.1
