[PATCH v4] firmware/psci: add support for SYSTEM_RESET2

[Sudeep Holla]

PSCI v1.1 introduced SYSTEM_RESET2 to allow both architectural resets
where the semantics are described by the PSCI specification itself as
well as vendor-specific resets. Currently only system warm reset
semantics is defined as part of architectural resets by the specification.

This patch implements support for SYSTEM_RESET2 by making using of
reboot_mode passed by the reboot infrastructure in the kernel.

Cc: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
Acked-by: Mark Rutland <mark.rutland@xxxxxxx>
Tested-by: Aaro Koskinen <aaro.koskinen@xxxxxxxxx>
Signed-off-by: Sudeep Holla <sudeep.holla@xxxxxxx>
---
 drivers/firmware/psci/psci.c | 24 +++++++++++++++++++++++-
 include/uapi/linux/psci.h    |  2 ++
 2 files changed, 25 insertions(+), 1 deletion(-)

v3->v4:
	- Rebased on linux-pm -next tree
	- Added Aaro Koskinen tested-by

v2->v3:
	- Added else condition so that if SYSTEM_RESET2 fails, it ends
	  up doing a system halt
	- Wrap single statement if..else with braces because of presence
	  of multiple line comment

diff --git a/drivers/firmware/psci/psci.c b/drivers/firmware/psci/psci.c
index eabd01383cd6..fe090ef43d28 100644
--- a/drivers/firmware/psci/psci.c
+++ b/drivers/firmware/psci/psci.c
@@ -88,6 +88,7 @@ static u32 psci_function_id[PSCI_FN_MAX];
 				PSCI_1_0_EXT_POWER_STATE_TYPE_MASK)

 static u32 psci_cpu_suspend_feature;
+static bool psci_system_reset2_supported;

 static inline bool psci_has_ext_power_state(void)
 {
@@ -258,7 +259,17 @@ static int get_set_conduit_method(struct device_node *np)

 static void psci_sys_reset(enum reboot_mode reboot_mode, const char *cmd)
 {
-	invoke_psci_fn(PSCI_0_2_FN_SYSTEM_RESET, 0, 0, 0);
+	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);
+	} else {
+		invoke_psci_fn(PSCI_0_2_FN_SYSTEM_RESET, 0, 0, 0);
+	}
 }

 static void psci_sys_poweroff(void)
@@ -460,6 +471,16 @@ static const struct platform_suspend_ops psci_suspend_ops = {
 	.enter          = psci_system_suspend_enter,
 };

+static void __init psci_init_system_reset2(void)
+{
+	int ret;
+
+	ret = psci_features(PSCI_FN_NATIVE(1_1, SYSTEM_RESET2));
+
+	if (ret != PSCI_RET_NOT_SUPPORTED)
+		psci_system_reset2_supported = true;
+}
+
 static void __init psci_init_system_suspend(void)
 {
 	int ret;
@@ -597,6 +618,7 @@ static int __init psci_probe(void)
 		psci_init_smccc();
 		psci_init_cpu_suspend();
 		psci_init_system_suspend();
+		psci_init_system_reset2();
 	}

 	return 0;
diff --git a/include/uapi/linux/psci.h b/include/uapi/linux/psci.h
index 581f72085c33..2fcad1dd0b0e 100644
--- a/include/uapi/linux/psci.h
+++ b/include/uapi/linux/psci.h
@@ -50,8 +50,10 @@
 #define PSCI_1_0_FN_PSCI_FEATURES		PSCI_0_2_FN(10)
 #define PSCI_1_0_FN_SYSTEM_SUSPEND		PSCI_0_2_FN(14)
 #define PSCI_1_0_FN_SET_SUSPEND_MODE		PSCI_0_2_FN(15)
+#define PSCI_1_1_FN_SYSTEM_RESET2		PSCI_0_2_FN(18)

 #define PSCI_1_0_FN64_SYSTEM_SUSPEND		PSCI_0_2_FN64(14)
+#define PSCI_1_1_FN64_SYSTEM_RESET2		PSCI_0_2_FN64(18)

 /* PSCI v0.2 power state encoding for CPU_SUSPEND function */
 #define PSCI_0_2_POWER_STATE_ID_MASK		0xffff
--
2.17.1