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>

1 files changed, 33 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;
 }