greybus: control: add interface deactivate prepare operation

Add the AP implementation for the Greybus Control Interface Deactivate
Prepare Operation. AP uses this Operation during the Power Down
transition to request the bridge to power down after it detects a
subsequent UniPro link hibernation.
Signed-off-by: David Lin <dtwlin@google.com>
Reviewed-by: Johan Hovold <johan@hovoldconsulting.com>
Signed-off-by: Alex Elder <elder@linaro.org>

drivers/staging/greybus/control.c

@@ -383,6 +383,29 @@ int gb_control_interface_suspend_prepare(struct gb_control *control)
 	return 0;
 }
 
+int gb_control_interface_deactivate_prepare(struct gb_control *control)
+{
+	struct gb_control_intf_pm_response response;
+	int ret;
+
+	ret = gb_operation_sync(control->connection,
+				GB_CONTROL_TYPE_INTF_DEACTIVATE_PREPARE, NULL,
+				0, &response, sizeof(response));
+	if (ret) {
+		dev_err(&control->dev, "failed to send interface deactivate prepare: %d\n",
+			ret);
+		return ret;
+	}
+
+	if (response.status != GB_CONTROL_INTF_PM_OK) {
+		dev_err(&control->dev, "interface error while preparing deactivate: %d\n",
+			response.status);
+		return gb_control_interface_pm_status_map(response.status);
+	}
+
+	return 0;
+}
+
 static ssize_t vendor_string_show(struct device *dev,
 			struct device_attribute *attr, char *buf)
 {

drivers/staging/greybus/control.h

@@ -57,4 +57,5 @@ int gb_control_bundle_resume(struct gb_control *control, u8 bundle_id);
 int gb_control_bundle_deactivate(struct gb_control *control, u8 bundle_id);
 int gb_control_bundle_activate(struct gb_control *control, u8 bundle_id);
 int gb_control_interface_suspend_prepare(struct gb_control *control);
+int gb_control_interface_deactivate_prepare(struct gb_control *control);
 #endif /* __CONTROL_H */

drivers/staging/greybus/greybus_protocols.h

@@ -131,6 +131,7 @@ struct gb_protocol_version_response {
 #define GB_CONTROL_TYPE_BUNDLE_DEACTIVATE	0x11
 #define GB_CONTROL_TYPE_BUNDLE_ACTIVATE		0x12
 #define GB_CONTROL_TYPE_INTF_SUSPEND_PREPARE		0x13
+#define GB_CONTROL_TYPE_INTF_DEACTIVATE_PREPARE	0x14
 
 struct gb_control_version_request {
 	__u8	major;