mfd: cros_ec: Prevent data transfer while device is suspended

The cros_ec driver is still active while the device is suspended.
Besides that, it also tries to transfer data even after the I2C host had
been suspended. This patch uses a simple flag to prevent this.

Signed-off-by: Joseph Lo <josephl@nvidia.com>
Signed-off-by: Thierry Escande <thierry.escande@collabora.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/mfd/cros_ec.c

@@ -165,6 +165,7 @@ int cros_ec_suspend(struct cros_ec_device *ec_dev)
 
 	disable_irq(ec_dev->irq);
 	ec_dev->was_wake_device = ec_dev->wake_enabled;
+	ec_dev->suspended = true;
 
 	return 0;
 }
@@ -179,6 +180,7 @@ static void cros_ec_drain_events(struct cros_ec_device *ec_dev)
 
 int cros_ec_resume(struct cros_ec_device *ec_dev)
 {
+	ec_dev->suspended = false;
 	enable_irq(ec_dev->irq);
 
 	/*

drivers/platform/chrome/cros_ec_proto.c

@@ -447,6 +447,11 @@ static int get_next_event(struct cros_ec_device *ec_dev)
 	struct cros_ec_command *msg = (struct cros_ec_command *)&buffer;
 	int ret;
 
+	if (ec_dev->suspended) {
+		dev_dbg(ec_dev->dev, "Device suspended.\n");
+		return -EHOSTDOWN;
+	}
+
 	msg->version = 0;
 	msg->command = EC_CMD_GET_NEXT_EVENT;
 	msg->insize = sizeof(ec_dev->event_data);

include/linux/mfd/cros_ec.h

@@ -103,6 +103,7 @@ struct cros_ec_command {
  * @din_size: size of din buffer to allocate (zero to use static din)
  * @dout_size: size of dout buffer to allocate (zero to use static dout)
  * @wake_enabled: true if this device can wake the system from sleep
+ * @suspended: true if this device had been suspended
  * @cmd_xfer: send command to EC and get response
  *     Returns the number of bytes received if the communication succeeded, but
  *     that doesn't mean the EC was happy with the command. The caller
@@ -136,6 +137,7 @@ struct cros_ec_device {
 	int din_size;
 	int dout_size;
 	bool wake_enabled;
+	bool suspended;
 	int (*cmd_xfer)(struct cros_ec_device *ec,
 			struct cros_ec_command *msg);
 	int (*pkt_xfer)(struct cros_ec_device *ec,