[PATCH v2 2/3] firmware: psci: Add support for dt-supplied SYSTEM_RESET2 type

[Elliot Berman <eberman@xxxxxxxxxxxxxx>]

Some implementors of PSCI may relax the requirements of the PSCI
architectural warm reset. In order to comply with PSCI specification, a
different reset_type value must be used. The alternate PSCI
SYSTEM_RESET2 may be used in all warm/soft reboot scenarios, replacing
the architectural warm reset.

Signed-off-by: Elliot Berman <eberman@xxxxxxxxxxxxxx>
---
 drivers/firmware/psci/psci.c | 22 ++++++++++++++++++----
 include/uapi/linux/psci.h    |  2 ++
 2 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/drivers/firmware/psci/psci.c b/drivers/firmware/psci/psci.c
index 2937d44..8f4609c 100644
--- a/drivers/firmware/psci/psci.c
+++ b/drivers/firmware/psci/psci.c
@@ -90,6 +90,8 @@ static u32 psci_function_id[PSCI_FN_MAX];
 
 static u32 psci_cpu_suspend_feature;
 static bool psci_system_reset2_supported;
+static u32 psci_sys_reset2_reset_param =
+	PSCI_1_1_SYSTEM_RESET2_SYSTEM_WARM_RESET;
 
 static inline bool psci_has_ext_power_state(void)
 {
@@ -272,11 +274,10 @@ static void psci_sys_reset(enum reboot_mode reboot_mode, const char *cmd)
 	if ((reboot_mode == REBOOT_WARM || reboot_mode == REBOOT_SOFT) &&
 	    psci_system_reset2_supported) {
 		/*
-		 * reset_type[31] = 0 (architectural)
-		 * reset_type[30:0] = 0 (SYSTEM_WARM_RESET)
 		 * cookie = 0 (ignored by the implementation)
 		 */
-		invoke_psci_fn(PSCI_FN_NATIVE(1_1, SYSTEM_RESET2), 0, 0, 0);
+		invoke_psci_fn(PSCI_FN_NATIVE(1_1, SYSTEM_RESET2),
+			       psci_sys_reset2_reset_param, 0, 0);
 	} else {
 		invoke_psci_fn(PSCI_0_2_FN_SYSTEM_RESET, 0, 0, 0);
 	}
@@ -493,6 +494,7 @@ typedef int (*psci_initcall_t)(const struct device_node *);
 static int __init psci_0_2_init(struct device_node *np)
 {
 	int err;
+	u32 param;
 
 	err = get_set_conduit_method(np);
 	if (err)
@@ -505,7 +507,19 @@ static int __init psci_0_2_init(struct device_node *np)
 	 * can be carried out according to the specific version reported
 	 * by firmware
 	 */
-	return psci_probe();
+	err = psci_probe();
+	if (err)
+		return err;
+
+	if (psci_system_reset2_supported &&
+	    !of_property_read_u32(np, "arm,psci-sys-reset2-param", &param)) {
+		if ((s32)param > 0)
+			pr_warn("%08x is an invalid architectural reset type.\n",
+				param);
+		psci_sys_reset2_reset_param = param;
+	}
+
+	return 0;
 }
 
 /*
diff --git a/include/uapi/linux/psci.h b/include/uapi/linux/psci.h
index 2fcad1d..d786ec8 100644
--- a/include/uapi/linux/psci.h
+++ b/include/uapi/linux/psci.h
@@ -55,6 +55,8 @@
 #define PSCI_1_0_FN64_SYSTEM_SUSPEND		PSCI_0_2_FN64(14)
 #define PSCI_1_1_FN64_SYSTEM_RESET2		PSCI_0_2_FN64(18)
 
+#define PSCI_1_1_SYSTEM_RESET2_SYSTEM_WARM_RESET	0
+
 /* PSCI v0.2 power state encoding for CPU_SUSPEND function */
 #define PSCI_0_2_POWER_STATE_ID_MASK		0xffff
 #define PSCI_0_2_POWER_STATE_ID_SHIFT		0
-- 
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