firmware: psci: Extend psci_set_osi_mode() to allow reset to PC mode

The current user (cpuidle-psci) of psci_set_osi_mode() only needs to enable
the PSCI OSI mode. Although, as subsequent changes shows, there is a need
to be able to reset back into the PSCI PC mode.

Therefore, let's extend psci_set_osi_mode() to take a bool as in-parameter,
to let the user indicate whether to enable OSI or to switch back to PC
mode.

Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Author: Ulf Hansson

drivers/cpuidle/cpuidle-psci-domain.c

@@ -278,7 +278,7 @@ static int psci_cpuidle_domain_probe(struct platform_device *pdev)
 		goto remove_pd;
 
 	/* Try to enable OSI mode. */
-	ret = psci_set_osi_mode();
+	ret = psci_set_osi_mode(true);
 	if (ret) {
 		pr_warn("failed to enable OSI mode: %d\n", ret);
 		psci_pd_remove_topology(np);

drivers/firmware/psci/psci.c

@@ -151,12 +151,15 @@ static u32 psci_get_version(void)
 	return invoke_psci_fn(PSCI_0_2_FN_PSCI_VERSION, 0, 0, 0);
 }
 
-int psci_set_osi_mode(void)
+int psci_set_osi_mode(bool enable)
 {
+	unsigned long suspend_mode;
 	int err;
 
-	err = invoke_psci_fn(PSCI_1_0_FN_SET_SUSPEND_MODE,
-			     PSCI_1_0_SUSPEND_MODE_OSI, 0, 0);
+	suspend_mode = enable ? PSCI_1_0_SUSPEND_MODE_OSI :
+			PSCI_1_0_SUSPEND_MODE_PC;
+
+	err = invoke_psci_fn(PSCI_1_0_FN_SET_SUSPEND_MODE, suspend_mode, 0, 0);
 	return psci_to_linux_errno(err);
 }
 
@@ -546,8 +549,7 @@ static int __init psci_1_0_init(struct device_node *np)
 		pr_info("OSI mode supported.\n");
 
 		/* Default to PC mode. */
-		invoke_psci_fn(PSCI_1_0_FN_SET_SUSPEND_MODE,
-			       PSCI_1_0_SUSPEND_MODE_PC, 0, 0);
+		psci_set_osi_mode(false);
 	}
 
 	return 0;

include/linux/psci.h

@@ -18,7 +18,7 @@ bool psci_tos_resident_on(int cpu);
 
 int psci_cpu_suspend_enter(u32 state);
 bool psci_power_state_is_valid(u32 state);
-int psci_set_osi_mode(void);
+int psci_set_osi_mode(bool enable);
 bool psci_has_osi_support(void);
 
 struct psci_operations {