firmware/psci: add support for SYSTEM_RESET2

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.

Acked-by: Mark Rutland <[e-mail]>
Tested-by: Aaro Koskinen <[e-mail]>
Signed-off-by: Sudeep Holla <[e-mail]>
Signed-off-by: Rafael J. Wysocki <[e-mail]>

drivers/firmware/psci/psci.c

···
 				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)
 {
···
 
 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)
···
 	.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;
···
 		psci_init_smccc();
 		psci_init_cpu_suspend();
 		psci_init_system_suspend();
+		psci_init_system_reset2();
 	}
 
 	return 0;

include/uapi/linux/psci.h

···
 #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