greybus: hd/es2: add cport_clear callback and ARPC

Add a host-device cport_clear callback, which will be called as part
of the new connection tear-down sequence to reset the CPort state.

Signed-off-by: Johan Hovold <[e-mail]>
Reviewed-by: Viresh Kumar <[e-mail]>
Acked-by: Sandeep Patil <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/staging/greybus/arpc.h

···
 #define ARPC_TYPE_CPORT_RESET			0x00
 #define ARPC_TYPE_CPORT_CONNECTED		0x01
 #define ARPC_TYPE_CPORT_QUIESCE			0x02
+#define ARPC_TYPE_CPORT_CLEAR			0x03
 
 struct arpc_cport_reset_req {
 	__le16 cport_id;
···
 	__le16 cport_id;
 	__le16 peer_space;
 	__le16 timeout;
+} __packed;
+
+struct arpc_cport_clear_req {
+	__le16 cport_id;
 } __packed;
 
 

drivers/staging/greybus/es2.c

···
 	return 0;
 }
 
+static int es2_cport_clear(struct gb_host_device *hd, u16 cport_id)
+{
+	struct es2_ap_dev *es2 = hd_to_es2(hd);
+	struct device *dev = &es2->usb_dev->dev;
+	struct arpc_cport_clear_req req;
+	int ret;
+
+	req.cport_id = cpu_to_le16(cport_id);
+	ret = arpc_sync(es2, ARPC_TYPE_CPORT_CLEAR, &req, sizeof(req),
+			NULL, ES2_ARPC_CPORT_TIMEOUT);
+	if (ret) {
+		dev_err(dev, "failed to clear cport %u: %d\n", cport_id, ret);
+		return ret;
+	}
+
+	return 0;
+}
+
 static int latency_tag_enable(struct gb_host_device *hd, u16 cport_id)
 {
 	int retval;
···
 	.cport_disable			= cport_disable,
 	.cport_connected		= es2_cport_connected,
 	.cport_quiesce			= es2_cport_quiesce,
+	.cport_clear			= es2_cport_clear,
 	.latency_tag_enable		= latency_tag_enable,
 	.latency_tag_disable		= latency_tag_disable,
 	.output				= output,

drivers/staging/greybus/hd.h

···
 	int (*cport_ping)(struct gb_host_device *hd, u16 cport_id);
 	int (*cport_quiesce)(struct gb_host_device *hd, u16 cport_id,
 				size_t peer_space, unsigned int timeout);
+	int (*cport_clear)(struct gb_host_device *hd, u16 cport_id);
+
 	int (*message_send)(struct gb_host_device *hd, u16 dest_cport_id,
 			struct gb_message *message, gfp_t gfp_mask);
 	void (*message_cancel)(struct gb_message *message);