[PATCH 2/2] drivers: firmware: psci: add system suspend support

[Sudeep Holla]

PSCI v1.0 introduces a new API called PSCI_SYSTEM_SUSPEND. This API
provides the mechanism by which the calling OS can request entry into
the deepest possible system sleep state.

It meets all the necessary preconditions for entrying suspend to RAM
state in Linux. This patch adds support for PSCI_SYSTEM_SUSPEND in psci
firmware and registers a psci system suspend operation to implement the
suspend-to-RAM(s2r) in a generic way on all the platforms implementing
PSCI.

Cc: Mark Rutland <mark.rutland at arm.com>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi at arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla at arm.com>
---
 drivers/firmware/psci.c   | 39 +++++++++++++++++++++++++++++++++++++++
 include/uapi/linux/psci.h |  2 ++
 2 files changed, 41 insertions(+)

diff --git a/drivers/firmware/psci.c b/drivers/firmware/psci.c
index 68d0c2f6d004..4f0359516119 100644
--- a/drivers/firmware/psci.c
+++ b/drivers/firmware/psci.c
@@ -20,11 +20,13 @@
 #include <linux/printk.h>
 #include <linux/psci.h>
 #include <linux/reboot.h>
+#include <linux/suspend.h>
 
 #include <uapi/linux/psci.h>
 
 #include <asm/system_misc.h>
 #include <asm/smp_plat.h>
+#include <asm/suspend.h>
 
 /*
  * While a 64-bit OS can make calls with SMC32 calling conventions, for some
@@ -222,6 +224,41 @@ static int __init psci_features(u32 psci_func_id)
 			      psci_func_id, 0, 0);
 }
 
+static int psci_system_suspend(unsigned long entry_point)
+{
+	return invoke_psci_fn(PSCI_0_2_FN_NATIVE(SYSTEM_SUSPEND),
+			      entry_point, 0, 0);
+}
+
+static int psci_system_suspend_finisher(unsigned long unused)
+{
+	return psci_system_suspend(virt_to_phys(cpu_resume));
+}
+
+static int psci_system_suspend_enter(suspend_state_t state)
+{
+	if (state != PM_SUSPEND_MEM)
+		return 0;
+
+	return cpu_suspend(0, psci_system_suspend_finisher);
+}
+
+static const struct platform_suspend_ops psci_suspend_ops = {
+	.valid          = suspend_valid_only_mem,
+	.enter          = psci_system_suspend_enter,
+};
+
+static void __init psci_init_system_suspend(void)
+{
+	if (!IS_ENABLED(CONFIG_SUSPEND))
+		return;
+
+	if (psci_features(PSCI_0_2_FN_NATIVE(SYSTEM_SUSPEND)))
+		return;
+
+	suspend_set_ops(&psci_suspend_ops);
+}
+
 static void __init psci_init_cpu_suspend(void)
 {
 	int feature = psci_features(psci_function_id[PSCI_FN_CPU_SUSPEND]);
@@ -310,6 +347,8 @@ static int __init psci_probe(void)
 
 	psci_init_cpu_suspend();
 
+	psci_init_system_suspend();
+
 	return 0;
 }
 
diff --git a/include/uapi/linux/psci.h b/include/uapi/linux/psci.h
index 2598d7c9bf20..62b054524819 100644
--- a/include/uapi/linux/psci.h
+++ b/include/uapi/linux/psci.h
@@ -39,12 +39,14 @@
 #define PSCI_0_2_FN_MIGRATE_INFO_UP_CPU		PSCI_0_2_FN(7)
 #define PSCI_0_2_FN_SYSTEM_OFF			PSCI_0_2_FN(8)
 #define PSCI_0_2_FN_SYSTEM_RESET		PSCI_0_2_FN(9)
+#define PSCI_0_2_FN_SYSTEM_SUSPEND		PSCI_0_2_FN(14)
 
 #define PSCI_0_2_FN64_CPU_SUSPEND		PSCI_0_2_FN64(1)
 #define PSCI_0_2_FN64_CPU_ON			PSCI_0_2_FN64(3)
 #define PSCI_0_2_FN64_AFFINITY_INFO		PSCI_0_2_FN64(4)
 #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_0_2_FN64_SYSTEM_SUSPEND		PSCI_0_2_FN64(14)
 
 #define PSCI_1_0_FN_PSCI_FEATURES		PSCI_0_2_FN(10)
 
-- 
1.9.1