[PATCH v2] drivers: firmware: psci: add support for warm reset

[Aaro Koskinen]

From: Aaro Koskinen <aaro.koskinen@xxxxxxxxx>

Add support for warm reset using SYSTEM_RESET2 introduced in PSCI
1.1 specification.

Signed-off-by: Aaro Koskinen <aaro.koskinen@xxxxxxxxx>
---

	v2: Added #define PSCI_1_1_SYSTEM_RESET_WARM. 
	    Refactored psci_probe.

	v1: https://marc.info/?l=linux-arm-kernel&m=155431514204495&w=2

 drivers/firmware/psci.c   | 42 ++++++++++++++++++++++++++++++++++-----
 include/uapi/linux/psci.h |  6 ++++++
 2 files changed, 43 insertions(+), 5 deletions(-)

diff --git a/drivers/firmware/psci.c b/drivers/firmware/psci.c
index c80ec1d03274..004a394de2c3 100644
--- a/drivers/firmware/psci.c
+++ b/drivers/firmware/psci.c
@@ -73,6 +73,7 @@ enum psci_function {
 	PSCI_FN_CPU_ON,
 	PSCI_FN_CPU_OFF,
 	PSCI_FN_MIGRATE,
+	PSCI_FN_SYSTEM_RESET2,
 	PSCI_FN_MAX,
 };
 
@@ -256,6 +257,15 @@ 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);
 }
 
+static void psci_sys_reset2(enum reboot_mode reboot_mode, const char *cmd)
+{
+	if (reboot_mode == REBOOT_WARM)
+		invoke_psci_fn(psci_function_id[PSCI_FN_SYSTEM_RESET2],
+			       PSCI_1_1_SYSTEM_RESET_WARM, 0, 0);
+	else
+		psci_sys_reset(reboot_mode, cmd);
+}
+
 static void psci_sys_poweroff(void)
 {
 	invoke_psci_fn(PSCI_0_2_FN_SYSTEM_OFF, 0, 0, 0);
@@ -564,6 +574,20 @@ static void __init psci_0_2_set_functions(void)
 	pm_power_off = psci_sys_poweroff;
 }
 
+static void __init psci_1_1_set_functions(void)
+{
+	int sys_reset2;
+	int feature;
+
+	sys_reset2 = PSCI_FN_NATIVE(1_1, SYSTEM_RESET2);
+	feature	= psci_features(sys_reset2);
+
+	if (feature != PSCI_RET_NOT_SUPPORTED) {
+		psci_function_id[PSCI_FN_SYSTEM_RESET2] = sys_reset2;
+		arm_pm_restart = psci_sys_reset2;
+	}
+}
+
 /*
  * Probe function for PSCI firmware versions >= 0.2
  */
@@ -584,11 +608,19 @@ static int __init psci_probe(void)
 
 	psci_init_migrate();
 
-	if (PSCI_VERSION_MAJOR(ver) >= 1) {
-		psci_init_smccc();
-		psci_init_cpu_suspend();
-		psci_init_system_suspend();
-	}
+	if (ver < PSCI_VERSION(1, 0))
+		return 0;
+
+	/* PSCI 1.0 setup */
+	psci_init_smccc();
+	psci_init_cpu_suspend();
+	psci_init_system_suspend();
+
+	if (ver < PSCI_VERSION(1, 1))
+		return 0;
+
+	/* PSCI 1.1 setup */
+	psci_1_1_set_functions();
 
 	return 0;
 }
diff --git a/include/uapi/linux/psci.h b/include/uapi/linux/psci.h
index b3bcabe380da..bf5a90c05e79 100644
--- a/include/uapi/linux/psci.h
+++ b/include/uapi/linux/psci.h
@@ -52,6 +52,12 @@
 
 #define PSCI_1_0_FN64_SYSTEM_SUSPEND		PSCI_0_2_FN64(14)
 
+#define PSCI_1_1_FN_SYSTEM_RESET2		PSCI_0_2_FN(18)
+#define PSCI_1_1_FN64_SYSTEM_RESET2		PSCI_0_2_FN64(18)
+
+/* PSCI v1.1 parameter values for SYSTEM_RESET2 */
+#define PSCI_1_1_SYSTEM_RESET_WARM		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
-- 
2.17.0