firmware: arm_scmi: Add system power protocol support

Add bare protocol support for SCMI system power protocol as needed by
an OSPM agent: basic initialization and SYSTEM_POWER_STATE_NOTIFIER
core notification support.

No event-handling logic is attached to such notification..

Link: https://lore.kernel.org/r/20200907174657.32466-2-cristian.marussi@arm.com
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

drivers/firmware/arm_scmi/Makefile

@@ -5,5 +5,5 @@ scmi-driver-y = driver.o notify.o
 scmi-transport-y = shmem.o
 scmi-transport-$(CONFIG_MAILBOX) += mailbox.o
 scmi-transport-$(CONFIG_HAVE_ARM_SMCCC_DISCOVERY) += smc.o
-scmi-protocols-y = base.o clock.o perf.o power.o reset.o sensors.o
+scmi-protocols-y = base.o clock.o perf.o power.o reset.o sensors.o system.o
 obj-$(CONFIG_ARM_SCMI_POWER_DOMAIN) += scmi_pm_domain.o

drivers/firmware/arm_scmi/system.c

@@ -0,0 +1,136 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * System Control and Management Interface (SCMI) System Power Protocol
+ *
+ * Copyright (C) 2020 ARM Ltd.
+ */
+
+#define pr_fmt(fmt) "SCMI Notifications SYSTEM - " fmt
+
+#include <linux/scmi_protocol.h>
+
+#include "common.h"
+#include "notify.h"
+
+#define SCMI_SYSTEM_NUM_SOURCES		1
+
+enum scmi_system_protocol_cmd {
+	SYSTEM_POWER_STATE_NOTIFY = 0x5,
+};
+
+struct scmi_system_power_state_notify {
+	__le32 notify_enable;
+};
+
+struct scmi_system_power_state_notifier_payld {
+	__le32 agent_id;
+	__le32 flags;
+	__le32 system_state;
+};
+
+struct scmi_system_info {
+	u32 version;
+};
+
+static int scmi_system_request_notify(const struct scmi_handle *handle,
+				      bool enable)
+{
+	int ret;
+	struct scmi_xfer *t;
+	struct scmi_system_power_state_notify *notify;
+
+	ret = scmi_xfer_get_init(handle, SYSTEM_POWER_STATE_NOTIFY,
+				 SCMI_PROTOCOL_SYSTEM, sizeof(*notify), 0, &t);
+	if (ret)
+		return ret;
+
+	notify = t->tx.buf;
+	notify->notify_enable = enable ? cpu_to_le32(BIT(0)) : 0;
+
+	ret = scmi_do_xfer(handle, t);
+
+	scmi_xfer_put(handle, t);
+	return ret;
+}
+
+static int scmi_system_set_notify_enabled(const struct scmi_handle *handle,
+					  u8 evt_id, u32 src_id, bool enable)
+{
+	int ret;
+
+	ret = scmi_system_request_notify(handle, enable);
+	if (ret)
+		pr_debug("FAIL_ENABLE - evt[%X] - ret:%d\n", evt_id, ret);
+
+	return ret;
+}
+
+static void *scmi_system_fill_custom_report(const struct scmi_handle *handle,
+					    u8 evt_id, ktime_t timestamp,
+					    const void *payld, size_t payld_sz,
+					    void *report, u32 *src_id)
+{
+	const struct scmi_system_power_state_notifier_payld *p = payld;
+	struct scmi_system_power_state_notifier_report *r = report;
+
+	if (evt_id != SCMI_EVENT_SYSTEM_POWER_STATE_NOTIFIER ||
+	    sizeof(*p) != payld_sz)
+		return NULL;
+
+	r->timestamp = timestamp;
+	r->agent_id = le32_to_cpu(p->agent_id);
+	r->flags = le32_to_cpu(p->flags);
+	r->system_state = le32_to_cpu(p->system_state);
+	*src_id = 0;
+
+	return r;
+}
+
+static const struct scmi_event system_events[] = {
+	{
+		.id = SCMI_EVENT_SYSTEM_POWER_STATE_NOTIFIER,
+		.max_payld_sz =
+			sizeof(struct scmi_system_power_state_notifier_payld),
+		.max_report_sz =
+			sizeof(struct scmi_system_power_state_notifier_report),
+	},
+};
+
+static const struct scmi_event_ops system_event_ops = {
+	.set_notify_enabled = scmi_system_set_notify_enabled,
+	.fill_custom_report = scmi_system_fill_custom_report,
+};
+
+static int scmi_system_protocol_init(struct scmi_handle *handle)
+{
+	u32 version;
+	struct scmi_system_info *pinfo;
+
+	scmi_version_get(handle, SCMI_PROTOCOL_SYSTEM, &version);
+
+	dev_dbg(handle->dev, "System Power Version %d.%d\n",
+		PROTOCOL_REV_MAJOR(version), PROTOCOL_REV_MINOR(version));
+
+	pinfo = devm_kzalloc(handle->dev, sizeof(*pinfo), GFP_KERNEL);
+	if (!pinfo)
+		return -ENOMEM;
+
+	scmi_register_protocol_events(handle,
+				      SCMI_PROTOCOL_SYSTEM, SCMI_PROTO_QUEUE_SZ,
+				      &system_event_ops,
+				      system_events,
+				      ARRAY_SIZE(system_events),
+				      SCMI_SYSTEM_NUM_SOURCES);
+
+	pinfo->version = version;
+	handle->system_priv = pinfo;
+
+	return 0;
+}
+
+static int __init scmi_system_init(void)
+{
+	return scmi_protocol_register(SCMI_PROTOCOL_SYSTEM,
+				      &scmi_system_protocol_init);
+}
+subsys_initcall(scmi_system_init);

include/linux/scmi_protocol.h

@@ -292,6 +292,7 @@ struct scmi_handle {
 	void *sensor_priv;
 	void *reset_priv;
 	void *notify_priv;
+	void *system_priv;
 };
 
 enum scmi_std_protocol {
@@ -304,6 +305,15 @@ enum scmi_std_protocol {
 	SCMI_PROTOCOL_RESET = 0x16,
 };
 
+enum scmi_system_events {
+	SCMI_SYSTEM_SHUTDOWN,
+	SCMI_SYSTEM_COLDRESET,
+	SCMI_SYSTEM_WARMRESET,
+	SCMI_SYSTEM_POWERUP,
+	SCMI_SYSTEM_SUSPEND,
+	SCMI_SYSTEM_MAX
+};
+
 struct scmi_device {
 	u32 id;
 	u8 protocol_id;
@@ -378,6 +388,7 @@ enum scmi_notification_events {
 	SCMI_EVENT_SENSOR_TRIP_POINT_EVENT = 0x0,
 	SCMI_EVENT_RESET_ISSUED = 0x0,
 	SCMI_EVENT_BASE_ERROR_EVENT = 0x0,
+	SCMI_EVENT_SYSTEM_POWER_STATE_NOTIFIER = 0x0,
 };
 
 struct scmi_power_state_changed_report {
@@ -387,6 +398,13 @@ struct scmi_power_state_changed_report {
 	unsigned int	power_state;
 };
 
+struct scmi_system_power_state_notifier_report {
+	ktime_t		timestamp;
+	unsigned int	agent_id;
+	unsigned int	flags;
+	unsigned int	system_state;
+};
+
 struct scmi_perf_limits_report {
 	ktime_t		timestamp;
 	unsigned int	agent_id;