Re: [PATCH v10 05/10] firmware: psci: Implement vendor-specific reset-types as reboot-mode

[Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>]

On 7/10/25 11:15 AM, Shivendra Pratap wrote:
> SoC vendors have different types of resets which are controlled
> through various hardware registers. For instance, Qualcomm SoC
> may have a requirement that reboot with “bootloader” command
> should reboot the device to bootloader flashing mode and reboot
> with “edl” should reboot the device into 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 spec defines, SYSTEM_RESET2, vendor-specific
> reset which can help align this requirement. Add support for PSCI
> SYSTEM_RESET2, vendor-specific resets and align the implementation
> to allow user-space initiated reboots to trigger these resets.
> 
> Introduce a late_initcall to register PSCI vendor-specific resets
> as reboot-mode arguments like reset_type and cookie. For a SoC
> where, PSCI vendor-specific system_reset2 is supported, the
> appropriate value gets filled to reset_type and cookie during
> this reboot-mode hook registration. If the secure firmware
> supports PSCI system_reset2, restart notifier will make secure
> call to trigger appropriate requested reset type.
> 
> By using the above implementation, usespace will be able to issue
> such resets using the reboot() system call with the "*arg"
> parameter as a string based command. The commands can be defined
> in PSCI device tree node as “reset-types” and are based on the
> reboot-mode based commands.
> 
> Signed-off-by: Shivendra Pratap <shivendra.pratap@oss.qualcomm.com>
> ---
>  drivers/firmware/psci/Kconfig |  1 +
>  drivers/firmware/psci/psci.c  | 53 ++++++++++++++++++++++++++++++++++++++++++-
>  2 files changed, 53 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/firmware/psci/Kconfig b/drivers/firmware/psci/Kconfig
> index 97944168b5e66aea1e38a7eb2d4ced8348fce64b..9d65fe7b06a6429de8a26d06f9384e5c93f36e5f 100644
> --- a/drivers/firmware/psci/Kconfig
> +++ b/drivers/firmware/psci/Kconfig
> @@ -1,6 +1,7 @@
>  # SPDX-License-Identifier: GPL-2.0-only
>  config ARM_PSCI_FW
>  	bool
> +	select REBOOT_MODE
>  
>  config ARM_PSCI_CHECKER
>  	bool "ARM PSCI checker"
> diff --git a/drivers/firmware/psci/psci.c b/drivers/firmware/psci/psci.c
> index 38ca190d4a22d6e7e0f06420e8478a2b0ec2fe6f..87293f78ed83eb33ba67ded73728729811693ea3 100644
> --- a/drivers/firmware/psci/psci.c
> +++ b/drivers/firmware/psci/psci.c
> @@ -13,10 +13,13 @@
>  #include <linux/errno.h>
>  #include <linux/linkage.h>
>  #include <linux/of.h>
> +#include <linux/of_platform.h>
> +#include <linux/platform_device.h>
>  #include <linux/pm.h>
>  #include <linux/printk.h>
>  #include <linux/psci.h>
>  #include <linux/reboot.h>
> +#include <linux/reboot-mode.h>
>  #include <linux/slab.h>
>  #include <linux/suspend.h>
>  
> @@ -51,6 +54,14 @@ static int resident_cpu = -1;
>  struct psci_operations psci_ops;
>  static enum arm_smccc_conduit psci_conduit = SMCCC_CONDUIT_NONE;
>  
> +struct psci_vendor_sysreset2 {
> +	u32 reset_type;
> +	u32 cookie;
> +	bool valid;
> +};
> +
> +static struct psci_vendor_sysreset2 vendor_reset;
> +
>  bool psci_tos_resident_on(int cpu)
>  {
>  	return cpu == resident_cpu;
> @@ -309,7 +320,14 @@ static int get_set_conduit_method(const struct device_node *np)
>  static int psci_sys_reset(struct notifier_block *nb, unsigned long action,
>  			  void *data)
>  {
> -	if ((reboot_mode == REBOOT_WARM || reboot_mode == REBOOT_SOFT) &&
> +	if (vendor_reset.valid && psci_system_reset2_supported) {
> +		/*
> +		 * if vendor_reset.valid is true call sys reset2 with
> +		 * the vendor_reset(reset_type and cookie).
> +		 */

This comment repeats the line above and below it without
bringing additional value

Konrad

> +		invoke_psci_fn(PSCI_FN_NATIVE(1_1, SYSTEM_RESET2), vendor_reset.reset_type,
> +			       vendor_reset.cookie, 0);
> +	} else if ((reboot_mode == REBOOT_WARM || reboot_mode == REBOOT_SOFT) &&
>  	    psci_system_reset2_supported) {
>  		/*
>  		 * reset_type[31] = 0 (architectural)
> @@ -547,6 +565,39 @@ static const struct platform_suspend_ops psci_suspend_ops = {
>  	.enter          = psci_system_suspend_enter,
>  };
>  
> +static int psci_set_vendor_sys_reset2(struct reboot_mode_driver *reboot,
> +				      u32 reset_type, u32 cookie)
> +{
> +	if (psci_system_reset2_supported) {
> +		vendor_reset.reset_type = PSCI_1_1_RESET_TYPE_VENDOR_START | reset_type;
> +		vendor_reset.cookie = cookie;
> +		vendor_reset.valid = true;
> +	}
> +
> +	return NOTIFY_DONE;
> +}
> +
> +static int __init psci_init_vendor_reset(void)
> +{
> +	struct reboot_mode_driver *reboot;
> +	struct device_node *np;
> +
> +	np = of_find_node_by_name(NULL, "reset-types");
> +	if (!np)
> +		return -ENODEV;
> +
> +	reboot = kzalloc(sizeof(*reboot), GFP_KERNEL);
> +	if (!reboot) {
> +		of_node_put(np);
> +		return -ENOMEM;
> +	}
> +
> +	reboot->write_with_cookie = psci_set_vendor_sys_reset2;
> +
> +	return reboot_mode_register(reboot, np);
> +}
> +late_initcall(psci_init_vendor_reset)
> +
>  static void __init psci_init_system_reset2(void)
>  {
>  	int ret;
>