[PATCH 4/6] drivers: firmware: psci: add PSCI_FEATURES call

[Lorenzo Pieralisi]

PSCI v1.0 introduces a PSCI_FEATURES call that allows to probe for
features related to a specific function identifier.

This patch adds PSCI_FEATURES support to the PSCI firmware layer.

Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi at arm.com>
Cc: Mark Rutland <mark.rutland at arm.com>
---
 drivers/firmware/psci.c   | 6 ++++++
 include/uapi/linux/psci.h | 2 ++
 2 files changed, 8 insertions(+)

diff --git a/drivers/firmware/psci.c b/drivers/firmware/psci.c
index f1579a4..2330099 100644
--- a/drivers/firmware/psci.c
+++ b/drivers/firmware/psci.c
@@ -196,6 +196,12 @@ static void psci_sys_poweroff(void)
 	invoke_psci_fn(PSCI_0_2_FN_SYSTEM_OFF, 0, 0, 0);
 }
 
+static int __init psci_features(u32 psci_func_id)
+{
+	return invoke_psci_fn(PSCI_1_0_FN_PSCI_FEATURES,
+			      psci_func_id, 0, 0);
+}
+
 /*
  * Detect the presence of a resident Trusted OS which may cause CPU_OFF to
  * return DENIED (which would be fatal).
diff --git a/include/uapi/linux/psci.h b/include/uapi/linux/psci.h
index 64469e6..187b828d 100644
--- a/include/uapi/linux/psci.h
+++ b/include/uapi/linux/psci.h
@@ -46,6 +46,8 @@
 #define PSCI_0_2_FN64_MIGRATE			PSCI_0_2_FN64(5)
 #define PSCI_0_2_FN64_MIGRATE_INFO_UP_CPU	PSCI_0_2_FN64(7)
 
+#define PSCI_1_0_FN_PSCI_FEATURES		PSCI_0_2_FN(10)
+
 /* 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
-- 
2.2.1