[PATCH v3] firmware/psci: add support for SYSTEM_RESET2

Sudeep Holla
2019-04-12T10:02:39Z

PSCI v1.1 introduced SYSTEM_RESET2 to allow both architectural resets
where the semantics are described by the PSCI specification itself as
well as vendor-specific resets. Currently only system warm reset
semantics is defined as part of architectural resets by the specification.

This patch implements support for SYSTEM_RESET2 by making using of
reboot_mode passed by the reboot infrastructure in the kernel.

Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
---
drivers/firmware/psci.c | 24 +++++++++++++++++++++++-
include/uapi/linux/psci.h | 2 ++
2 files changed, 25 insertions(+), 1 deletion(-)

v2->v3:
- Added else condition so that if SYSTEM_RESET2 fails, it ends
up doing a system halt
- Wrap single statement if..else with braces because of presence
of multiple line comment

diff --git a/drivers/firmware/psci.c b/drivers/firmware/psci.c
index c80ec1d03274..c9ea8f38bd42 100644
--- a/drivers/firmware/psci.c
+++ b/drivers/firmware/psci.c
@@ -88,6 +88,7 @@ static u32 psci_function_id[PSCI_FN_MAX];
PSCI_1_0_EXT_POWER_STATE_TYPE_MASK)

static u32 psci_cpu_suspend_feature;
+static bool psci_system_reset2_supported;

static inline bool psci_has_ext_power_state(void)
{
@@ -253,7 +254,17 @@ static int get_set_conduit_method(struct device_node *np)

static void psci_sys_reset(enum reboot_mode reboot_mode, const char *cmd)
{
- invoke_psci_fn(PSCI_0_2_FN_SYSTEM_RESET, 0, 0, 0);
+ if ((reboot_mode == REBOOT_WARM || reboot_mode == REBOOT_SOFT) &&
+ psci_system_reset2_supported) {
+ /*
+ * reset_type[31] = 0 (architectural)
+ * reset_type[30:0] = 0 (SYSTEM_WARM_RESET)
+ * cookie = 0 (ignored by the implementation)
+ */
+ invoke_psci_fn(PSCI_FN_NATIVE(1_1, SYSTEM_RESET2), 0, 0, 0);
+ } else {
+ invoke_psci_fn(PSCI_0_2_FN_SYSTEM_RESET, 0, 0, 0);
+ }
}

static void psci_sys_poweroff(void)
@@ -451,6 +462,16 @@ static const struct platform_suspend_ops psci_suspend_ops = {
.enter = psci_system_suspend_enter,
};

+static void __init psci_init_system_reset2(void)
+{
+ int ret;
+
+ ret = psci_features(PSCI_FN_NATIVE(1_1, SYSTEM_RESET2));
+
+ if (ret != PSCI_RET_NOT_SUPPORTED)
+ psci_system_reset2_supported = true;
+}
+
static void __init psci_init_system_suspend(void)
{
int ret;
@@ -588,6 +609,7 @@ static int __init psci_probe(void)
psci_init_smccc();
psci_init_cpu_suspend();
psci_init_system_suspend();
+ psci_init_system_reset2();
}

return 0;
diff --git a/include/uapi/linux/psci.h b/include/uapi/linux/psci.h
index b3bcabe380da..5b0ba0062541 100644
--- a/include/uapi/linux/psci.h
+++ b/include/uapi/linux/psci.h
@@ -49,8 +49,10 @@

#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_1_FN_SYSTEM_RESET2 PSCI_0_2_FN(18)

#define PSCI_1_0_FN64_SYSTEM_SUSPEND PSCI_0_2_FN64(14)
+#define PSCI_1_1_FN64_SYSTEM_RESET2 PSCI_0_2_FN64(18)

/* PSCI v0.2 power state encoding for CPU_SUSPEND function */
#define PSCI_0_2_POWER_STATE_ID_MASK 0xffff
--
2.17.1