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

[Shivendra Pratap <shivendra.pratap@oss.qualcomm.com>]

On 7/10/2025 9:15 PM, Konrad Dybcio wrote:
> 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
Ack. will remove or modify the comment to make more sense.
thanks.
> 
> 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;
>>