[PATCH v12 4/8] firmware: psci: Implement vendor-specific resets as reboot-mode

Shivendra Pratap
2025-07-21T18:29:40Z

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 modes. Implement a reboot-mode write function that sets
reset_type and cookie values during the reboot notifier callback.
Introduce a firmware-based call for SYSTEM_RESET2 vendor-specific
reset in the psci_sys_reset path, using reset_type and cookie if
supported by secure firmware.

By using the above implementation, userspace 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 | 57 ++++++++++++++++++++++++++++++++++++++++++-
2 files changed, 57 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..8ce23fb931c71357899a942796d85ab8e37c2f62 100644
--- a/drivers/firmware/psci/psci.c
+++ b/drivers/firmware/psci/psci.c
@@ -17,6 +17,7 @@
#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 +52,14 @@ 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 +318,10 @@ 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) {
+ 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 +559,49 @@ 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, u64 magic)
+{
+ u32 magic_32;
+
+ if (psci_system_reset2_supported) {
+ magic_32 = magic & 0xFFFFFFFF;
+ vendor_reset.reset_type = PSCI_1_1_RESET_TYPE_VENDOR_START | magic_32;
+ vendor_reset.cookie = (magic >> 32) & 0xFFFFFFFF;
+ vendor_reset.valid = true;
+ }
+
+ return NOTIFY_DONE;
+}
+
+static int __init psci_init_vendor_reset(void)
+{
+ struct reboot_mode_driver *reboot;
+ struct device_node *np;
+ int ret;
+
+ np = of_find_node_by_path("/psci/reboot-mode");
+ if (!np)
+ return -ENODEV;
+
+ reboot = kzalloc(sizeof(*reboot), GFP_KERNEL);
+ if (!reboot) {
+ of_node_put(np);
+ return -ENOMEM;
+ }
+
+ reboot->write = psci_set_vendor_sys_reset2;
+
+ ret = reboot_mode_register(reboot, np);
+ if (ret) {
+ of_node_put(np);
+ kfree(reboot);
+ return ret;
+ }
+
+ return 0;
+}
+late_initcall(psci_init_vendor_reset)
+
static void __init psci_init_system_reset2(void)
{
int ret;

--
2.34.1