drivers: firmware: psci: add system suspend support

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 entering 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@arm.com>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Acked-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>

2 files changed, 36 insertions, 0 deletions

diff --git a/drivers/firmware/psci.c b/drivers/firmware/psci.c
index 1fa7284fb21d..492db42c4e08 100644
--- a/drivers/firmware/psci.c
+++ b/drivers/firmware/psci.c
@@ -20,12 +20,14 @@
 #include <linux/printk.h>
 #include <linux/psci.h>
 #include <linux/reboot.h>
+#include <linux/suspend.h>
 
 #include <uapi/linux/psci.h>
 
 #include <asm/cputype.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
@@ -223,6 +225,35 @@ static int __init psci_features(u32 psci_func_id)
                               psci_func_id, 0, 0);
 }
 
+static int psci_system_suspend(unsigned long unused)
+{
+        return invoke_psci_fn(PSCI_FN_NATIVE(1_0, SYSTEM_SUSPEND),
+                              virt_to_phys(cpu_resume), 0, 0);
+}
+
+static int psci_system_suspend_enter(suspend_state_t state)
+{
+        return cpu_suspend(0, psci_system_suspend);
+}
+
+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)
+{
+        int ret;
+
+        if (!IS_ENABLED(CONFIG_SUSPEND))
+                return;
+
+        ret = psci_features(PSCI_FN_NATIVE(1_0, SYSTEM_SUSPEND));
+
+        if (ret != PSCI_RET_NOT_SUPPORTED)
+                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]);
@@ -318,6 +349,8 @@ 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 0a9485f3c6c3..3d7a0fc021a7 100644
--- a/include/uapi/linux/psci.h
+++ b/include/uapi/linux/psci.h
@@ -47,6 +47,9 @@
 #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)
+#define PSCI_1_0_FN_SYSTEM_SUSPEND              PSCI_0_2_FN(14)
+
+#define PSCI_1_0_FN64_SYSTEM_SUSPEND            PSCI_0_2_FN64(14)
 
 /* PSCI v0.2 power state encoding for CPU_SUSPEND function */
 #define PSCI_0_2_POWER_STATE_ID_MASK            0xffff