mfd: cros_ec: Send suspend state notification to EC

Notify EC when going to or returning from suspend so that proper actions
related to wake events can be taken.

Signed-off-by: Shawn Nematbakhsh <shawnn@chromium.org>
Signed-off-by: Thierry Escande <thierry.escande@collabora.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/mfd/cros_ec.c

@@ -23,6 +23,7 @@
 #include <linux/module.h>
 #include <linux/mfd/core.h>
 #include <linux/mfd/cros_ec.h>
+#include <linux/suspend.h>
 #include <asm/unaligned.h>
 
 #define CROS_EC_DEV_EC_INDEX 0
@@ -65,6 +66,24 @@ static irqreturn_t ec_irq_thread(int irq, void *data)
 	return IRQ_HANDLED;
 }
 
+static int cros_ec_sleep_event(struct cros_ec_device *ec_dev, u8 sleep_event)
+{
+	struct {
+		struct cros_ec_command msg;
+		struct ec_params_host_sleep_event req;
+	} __packed buf;
+
+	memset(&buf, 0, sizeof(buf));
+
+	buf.req.sleep_event = sleep_event;
+
+	buf.msg.command = EC_CMD_HOST_SLEEP_EVENT;
+	buf.msg.version = 0;
+	buf.msg.outsize = sizeof(buf.req);
+
+	return cros_ec_cmd_xfer(ec_dev, &buf.msg);
+}
+
 int cros_ec_register(struct cros_ec_device *ec_dev)
 {
 	struct device *dev = ec_dev->dev;
@@ -136,6 +155,15 @@ int cros_ec_register(struct cros_ec_device *ec_dev)
 		}
 	}
 
+	/*
+	 * Clear sleep event - this will fail harmlessly on platforms that
+	 * don't implement the sleep event host command.
+	 */
+	err = cros_ec_sleep_event(ec_dev, 0);
+	if (err < 0)
+		dev_dbg(ec_dev->dev, "Error %d clearing sleep event to ec",
+			err);
+
 	dev_info(dev, "Chrome EC device registered\n");
 
 	return 0;
@@ -159,6 +187,16 @@ EXPORT_SYMBOL(cros_ec_remove);
 int cros_ec_suspend(struct cros_ec_device *ec_dev)
 {
 	struct device *dev = ec_dev->dev;
+	int ret;
+	u8 sleep_event;
+
+	sleep_event = pm_suspend_via_firmware() ? HOST_SLEEP_EVENT_S3_RESUME :
+						  HOST_SLEEP_EVENT_S0IX_RESUME;
+
+	ret = cros_ec_sleep_event(ec_dev, sleep_event);
+	if (ret < 0)
+		dev_dbg(ec_dev->dev, "Error %d sending suspend event to ec",
+			ret);
 
 	if (device_may_wakeup(dev))
 		ec_dev->wake_enabled = !enable_irq_wake(ec_dev->irq);
@@ -180,9 +218,20 @@ static void cros_ec_drain_events(struct cros_ec_device *ec_dev)
 
 int cros_ec_resume(struct cros_ec_device *ec_dev)
 {
+	int ret;
+	u8 sleep_event;
+
 	ec_dev->suspended = false;
 	enable_irq(ec_dev->irq);
 
+	sleep_event = pm_suspend_via_firmware() ? HOST_SLEEP_EVENT_S3_RESUME :
+						  HOST_SLEEP_EVENT_S0IX_RESUME;
+
+	ret = cros_ec_sleep_event(ec_dev, sleep_event);
+	if (ret < 0)
+		dev_dbg(ec_dev->dev, "Error %d sending resume event to ec",
+			ret);
+
 	/*
 	 * In some cases, we need to distinguish between events that occur
 	 * during suspend if the EC is not a wake source. For example,

include/linux/mfd/cros_ec_commands.h

@@ -2547,6 +2547,20 @@ struct ec_params_ext_power_current_limit {
 	uint32_t limit; /* in mA */
 } __packed;
 
+/* Inform the EC when entering a sleep state */
+#define EC_CMD_HOST_SLEEP_EVENT 0xa9
+
+enum host_sleep_event {
+	HOST_SLEEP_EVENT_S3_SUSPEND   = 1,
+	HOST_SLEEP_EVENT_S3_RESUME    = 2,
+	HOST_SLEEP_EVENT_S0IX_SUSPEND = 3,
+	HOST_SLEEP_EVENT_S0IX_RESUME  = 4
+};
+
+struct ec_params_host_sleep_event {
+	uint8_t sleep_event;
+} __packed;
+
 /*****************************************************************************/
 /* Smart battery pass-through */