[PATCH v2 4/5] drivers: firmware: psci: add extended stateid power_state support

[Lorenzo Pieralisi]

PSCI v1.0 augmented the power_state parameter format specification
(extended stateid) and introduced a way to probe it through the
PSCI_FEATURES interface.

This patch implements code that detects the power_state format at
run-time through the PSCI_FEATURES interface, so that the power_state
argument can be properly detected and validated in the kernel according
to the information provided through firmware.

Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi at arm.com>
Cc: Mark Rutland <mark.rutland at arm.com>
---
 drivers/firmware/psci.c   | 34 ++++++++++++++++++++++++++++++++--
 include/uapi/linux/psci.h | 12 ++++++++++++
 2 files changed, 44 insertions(+), 2 deletions(-)

diff --git a/drivers/firmware/psci.c b/drivers/firmware/psci.c
index 24ef3a8..bd2ba5b 100644
--- a/drivers/firmware/psci.c
+++ b/drivers/firmware/psci.c
@@ -75,14 +75,34 @@ static u32 psci_function_id[PSCI_FN_MAX];
 				PSCI_0_2_POWER_STATE_TYPE_MASK | \
 				PSCI_0_2_POWER_STATE_AFFL_MASK)
 
+#define PSCI_1_0_EXT_POWER_STATE_MASK		\
+				(PSCI_1_0_EXT_POWER_STATE_ID_MASK | \
+				PSCI_1_0_EXT_POWER_STATE_TYPE_MASK)
+
+static u32 psci_cpu_suspend_feature;
+
+static inline bool psci_has_ext_power_state(void)
+{
+	return psci_cpu_suspend_feature &
+				PSCI_1_0_FEATURES_CPU_SUSPEND_PF_MASK;
+}
+
 bool psci_power_state_loses_context(u32 state)
 {
-	return state & PSCI_0_2_POWER_STATE_TYPE_MASK;
+	const u32 mask = psci_has_ext_power_state() ?
+					PSCI_1_0_EXT_POWER_STATE_TYPE_MASK :
+					PSCI_0_2_POWER_STATE_TYPE_MASK;
+
+	return state & mask;
 }
 
 bool psci_power_state_is_valid(u32 state)
 {
-	return !(state & ~PSCI_0_2_POWER_STATE_MASK);
+	const u32 valid_mask = psci_has_ext_power_state() ?
+			       PSCI_1_0_EXT_POWER_STATE_MASK :
+			       PSCI_0_2_POWER_STATE_MASK;
+
+	return !(state & ~valid_mask);
 }
 
 static int psci_to_linux_errno(int errno)
@@ -203,6 +223,14 @@ static int __init psci_features(u32 psci_func_id)
 			      psci_func_id, 0, 0);
 }
 
+static void __init psci_init_cpu_suspend(void)
+{
+	int feature = psci_features(psci_function_id[PSCI_FN_CPU_SUSPEND]);
+
+	if (feature != PSCI_RET_NOT_SUPPORTED)
+		psci_cpu_suspend_feature = feature;
+}
+
 /*
  * Detect the presence of a resident Trusted OS which may cause CPU_OFF to
  * return DENIED (which would be fatal).
@@ -287,6 +315,8 @@ static int __init psci_probe(void)
 
 	psci_init_migrate();
 
+	psci_init_cpu_suspend();
+
 	return 0;
 }
 
diff --git a/include/uapi/linux/psci.h b/include/uapi/linux/psci.h
index 187b828d..0a9485f 100644
--- a/include/uapi/linux/psci.h
+++ b/include/uapi/linux/psci.h
@@ -58,6 +58,13 @@
 #define PSCI_0_2_POWER_STATE_AFFL_MASK		\
 				(0x3 << PSCI_0_2_POWER_STATE_AFFL_SHIFT)
 
+/* PSCI extended power state encoding for CPU_SUSPEND function */
+#define PSCI_1_0_EXT_POWER_STATE_ID_MASK	0xfffffff
+#define PSCI_1_0_EXT_POWER_STATE_ID_SHIFT	0
+#define PSCI_1_0_EXT_POWER_STATE_TYPE_SHIFT	30
+#define PSCI_1_0_EXT_POWER_STATE_TYPE_MASK	\
+				(0x1 << PSCI_1_0_EXT_POWER_STATE_TYPE_SHIFT)
+
 /* PSCI v0.2 affinity level state returned by AFFINITY_INFO */
 #define PSCI_0_2_AFFINITY_LEVEL_ON		0
 #define PSCI_0_2_AFFINITY_LEVEL_OFF		1
@@ -78,6 +85,11 @@
 #define PSCI_VERSION_MINOR(ver)			\
 		((ver) & PSCI_VERSION_MINOR_MASK)
 
+/* PSCI features decoding (>=1.0) */
+#define PSCI_1_0_FEATURES_CPU_SUSPEND_PF_SHIFT	1
+#define PSCI_1_0_FEATURES_CPU_SUSPEND_PF_MASK	\
+			(0x1 << PSCI_1_0_FEATURES_CPU_SUSPEND_PF_SHIFT)
+
 /* PSCI return values (inclusive of all PSCI versions) */
 #define PSCI_RET_SUCCESS			0
 #define PSCI_RET_NOT_SUPPORTED			-1
-- 
2.2.1