Re: [PATCH v11 0/8] Implement vendor resets for PSCI SYSTEM_RESET2

[Florian Fainelli <florian.fainelli@broadcom.com>]

On 7/17/25 05:46, Shivendra Pratap wrote:
> The PSCI SYSTEM_RESET2 call allows vendor firmware to define
> additional reset types which could be mapped to the reboot
> argument.
> 
> User-space should be able to reboot a device into different
> operational boot-states supported by underlying bootloader and
> firmware. Generally, some HW registers need to be written, based
> on which the bootloader and firmware decide the next boot state
> of device, after the reset. For example, a requirement on
> Qualcomm platforms may state that reboot with "bootloader"
> command, should reboot the device into bootloader flashing mode
> and reboot with “edl” command, should reboot the device into an
> Emergency flashing mode.  Setting up such reboots on Qualcomm
> devices can be inconsistent across SoC platforms and may require
> setting different HW registers, where some of these registers may
> not be accessible to HLOS. These knobs evolve over product
> generations and require more drivers.  PSCI defines a
> vendor-specific reset in SYSTEM_RESET2 spec, which enables the
> firmware to take care of underlying setting for any such
> supported vendor-specific reboot. Qualcomm firmwares are
> beginning to support and expose PSCI SYSTEM_RESET2
> vendor-specific reset types to simplify driver requirements from
> Linux. With such support added in the firmware, we now need a
> Linux interface which can make use of the firmware calls for PSCI
> vendor-specific resets. This will align such reboot requirement
> across platforms and vendors.
> 
> The current psci driver supports two types of resets –
> SYSTEM_RESET2 Arch warm-reset and SYSTEM_RESET cold-reset. The
> patchset introduces the PSCI SYSTEM_RESET2 vendor-specific reset
> into the reset path of the psci driver and aligns it to work with
> reboot system call - LINUX_REBOOT_CMD_RESTART2, when used along
> with a supported string-based command in “*arg”.
> 
> The patchset uses reboot-mode based commands, to define the
> supported vendor reset-types commands in psci device tree node
> and registers these commands with the reboot-mode framework.
> 
> The PSCI vendor-specific reset takes two arguments, being,
> reset_type and cookie as defined by the spec. To accommodate this
> requirement, enhance the reboot-mode framework to support two
> 32-bit arguments by switching to 64-bit magic values.
> 
> Along this line, the patchset also extends the reboot-mode
> framework to add a non-device-based registration function, which
> will allow drivers to register using device tree node, while
> keeping backward compatibility for existing users of reboot-mode.
> This will enable psci driver to register for reboot-mode and
> implement a write function, which will save the magic and then
> use it in psci reset path to make a vendor-specific reset call
> into the firmware. In addition, the patchset will expose a sysfs
> entry interface within reboot-mode which can be used by userspace
> to view the supported reboot-mode commands.
> 
> The list of vendor-specific reset commands remains open due to
> divergent requirements across vendors, but this can be
> streamlined and standardized through dedicated device tree
> bindings.
> 
> Currently three drivers register with reboot-mode framework -
> syscon-reboot-mode, nvmem-reboot-mode and qcom-pon. Consolidated
> list of commands currently added across various vendor DTs:
>   mode-loader
>   mode-normal
>   mode-bootloader
>   mode-charge
>   mode-fastboot
>   mode-reboot-ab-update
>   mode-recovery
>   mode-rescue
>   mode-shutdown-thermal
>   mode-shutdown-thermal-battery
> 
> Detailed list of commands being used by syscon-reboot-mode:
>      arm64/boot/dts/exynos/exynosautov9.dtsi:
> 	mode-bootloader = <EXYNOSAUTOV9_BOOT_BOOTLOADER>;
> 	mode-fastboot = <EXYNOSAUTOV9_BOOT_FASTBOOT>;
> 	mode-recovery = <EXYNOSAUTOV9_BOOT_RECOVERY>;
> 
>      arm64/boot/dts/exynos/google/gs101.dtsi:
>      	mode-bootloader = <0xfc>;
>      	mode-charge = <0x0a>;
>      	mode-fastboot = <0xfa>;
>      	mode-reboot-ab-update = <0x52>;
>      	mode-recovery = <0xff>;
>      	mode-rescue = <0xf9>;
>      	mode-shutdown-thermal = <0x51>;
>      	mode-shutdown-thermal-battery = <0x51>;
> 
>      arm64/boot/dts/hisilicon/hi3660-hikey960.dts:
>      	mode-normal = <0x77665501>;
>      	mode-bootloader = <0x77665500>;
>      	mode-recovery = <0x77665502>;
> 
>      arm64/boot/dts/hisilicon/hi6220-hikey.dts:
>      	mode-normal = <0x77665501>;
>      	mode-bootloader = <0x77665500>;
>      	mode-recovery = <0x77665502>;
> 
>      arm64/boot/dts/rockchip/px30.dtsi:
>      	mode-bootloader = <BOOT_BL_DOWNLOAD>;
>      	mode-fastboot = <BOOT_FASTBOOT>;
>      	mode-loader = <BOOT_BL_DOWNLOAD>;
>      	mode-normal = <BOOT_NORMAL>;
>      	mode-recovery = <BOOT_RECOVERY>;
> 
>      arm64/boot/dts/rockchip/rk3308.dtsi:
>      	mode-bootloader = <BOOT_BL_DOWNLOAD>;
>      	mode-loader = <BOOT_BL_DOWNLOAD>;
>      	mode-normal = <BOOT_NORMAL>;
>      	mode-recovery = <BOOT_RECOVERY>;
>      	mode-fastboot = <BOOT_FASTBOOT>;
> 
>      arm64/boot/dts/rockchip/rk3566-lckfb-tspi.dts:
>      	mode-normal = <BOOT_NORMAL>;
>      	mode-loader = <BOOT_BL_DOWNLOAD>;
> 			mode-recovery = <BOOT_RECOVERY>;
> 			mode-bootloader = <BOOT_FASTBOOT>;
> 
> Detailed list of commands being used by nvmem-reboot-mode:
>      arm64/boot/dts/qcom/pmXXXX.dtsi:(multiple qcom DTs)
> 			mode-recovery = <0x01>;
> 			mode-bootloader = <0x02>;
> 
> Previous discussions around SYSTEM_RESET2:
> - https://lore.kernel.org/lkml/20230724223057.1208122-2-quic_eberman@quicinc.com/T/
> - https://lore.kernel.org/all/4a679542-b48d-7e11-f33a-63535a5c68cb@quicinc.com/
> 
> Signed-off-by: Elliot Berman <quic_eberman@quicinc.com>
> Signed-off-by: Shivendra Pratap <shivendra.pratap@oss.qualcomm.com>

I really wished we had stuck with using "/psci/reset-types" because I 
thought that node name was stable, but regardless, on ARCH_BRCMSTB:

Tested-by: Florian Fainelli <florian.fainelli@broadcom.com>
-- 
Florian