From a86fe70b61b4e724fbab306bb7856a47fd8c8b11 Mon Sep 17 00:00:00 2001
From: Hemant Kumar <hemantk@codeaurora.org>
Date: Mon, 1 Feb 2016 18:50:28 -0800
Subject: [PATCH] usb: gadget: Add support for rndis flow control callback

Allow registration for data flow control call back from
rndis functions supporting different transport i.e.
BAM2BAM_IPA, GSI_IPA.

Change-Id: I09df5f7f81e9d9ed0cfd5e54d481db87727bbc75
Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>
---
 drivers/usb/gadget/function/f_rndis.c |  2 +-
 drivers/usb/gadget/function/rndis.c   | 59 ++++++++++++++++++++++++---
 drivers/usb/gadget/function/rndis.h   |  7 +++-
 3 files changed, 61 insertions(+), 7 deletions(-)

diff --git a/drivers/usb/gadget/function/f_rndis.c b/drivers/usb/gadget/function/f_rndis.c
index 3a28d8ac3b3d..13888821109d 100644
--- a/drivers/usb/gadget/function/f_rndis.c
+++ b/drivers/usb/gadget/function/f_rndis.c
@@ -1018,7 +1018,7 @@ static struct usb_function *rndis_alloc(struct usb_function_instance *fi)
 	rndis->port.func.disable = rndis_disable;
 	rndis->port.func.free_func = rndis_free;
 
-	params = rndis_register(rndis_response_available, rndis);
+	params = rndis_register(rndis_response_available, rndis, NULL);
 	if (IS_ERR(params)) {
 		kfree(rndis);
 		return ERR_CAST(params);
diff --git a/drivers/usb/gadget/function/rndis.c b/drivers/usb/gadget/function/rndis.c
index 2ec7171b3f04..2c806ea13e90 100644
--- a/drivers/usb/gadget/function/rndis.c
+++ b/drivers/usb/gadget/function/rndis.c
@@ -831,10 +831,16 @@ int rndis_msg_parser(struct rndis_params *params, u8 *buf)
 	case RNDIS_MSG_HALT:
 		pr_debug("%s: RNDIS_MSG_HALT\n",
 			__func__);
-		params->state = RNDIS_UNINITIALIZED;
-		if (params->dev) {
-			netif_carrier_off(params->dev);
-			netif_stop_queue(params->dev);
+		if (params->state == RNDIS_DATA_INITIALIZED) {
+			if (params->flow_ctrl_enable) {
+				params->flow_ctrl_enable(true, params);
+			} else {
+				if (params->dev) {
+					netif_carrier_off(params->dev);
+					netif_stop_queue(params->dev);
+				}
+			}
+			params->state = RNDIS_UNINITIALIZED;
 		}
 		return 0;
 
@@ -886,7 +892,8 @@ static inline void rndis_put_nr(int nr)
 	ida_simple_remove(&rndis_ida, nr);
 }
 
-struct rndis_params *rndis_register(void (*resp_avail)(void *v), void *v)
+struct rndis_params *rndis_register(void (*resp_avail)(void *v), void *v,
+	void (*flow_ctrl_enable)(bool enable, struct rndis_params *params))
 {
 	struct rndis_params *params;
 	int i;
@@ -930,6 +937,7 @@ struct rndis_params *rndis_register(void (*resp_avail)(void *v), void *v)
 	params->state = RNDIS_UNINITIALIZED;
 	params->media_state = RNDIS_MEDIA_STATE_DISCONNECTED;
 	params->resp_avail = resp_avail;
+	params->flow_ctrl_enable = flow_ctrl_enable;
 	params->v = v;
 	INIT_LIST_HEAD(&(params->resp_queue));
 	pr_debug("%s: configNr = %d\n", __func__, i);
@@ -1015,6 +1023,47 @@ void rndis_set_max_pkt_xfer(struct rndis_params *params, u8 max_pkt_per_xfer)
 	params->max_pkt_per_xfer = max_pkt_per_xfer;
 }
 
+/**
+ * rndis_flow_control: enable/disable flow control with USB RNDIS interface
+ * params - RNDIS network parameter
+ * enable_flow_control - true: perform flow control, false: disable flow control
+ *
+ * In hw accelerated mode, this function triggers functionality to start/stop
+ * endless transfers, otherwise it enables/disables RNDIS network interface.
+ */
+void rndis_flow_control(struct rndis_params *params, bool enable_flow_control)
+{
+	if (!params) {
+		pr_err("%s: failed, params NULL\n", __func__);
+		return;
+	}
+
+	pr_debug("%s(): params->state:%x\n", __func__, params->state);
+
+	if (enable_flow_control) {
+		if (params->state == RNDIS_DATA_INITIALIZED) {
+			if (params->flow_ctrl_enable) {
+				params->flow_ctrl_enable(enable_flow_control, params);
+			} else {
+				netif_carrier_off(params->dev);
+				netif_stop_queue(params->dev);
+			}
+		}
+		params->state = RNDIS_INITIALIZED;
+	} else {
+		if (params->state != RNDIS_DATA_INITIALIZED) {
+			if (params->flow_ctrl_enable) {
+				params->flow_ctrl_enable(enable_flow_control, params);
+			} else {
+				netif_carrier_on(params->dev);
+				if (netif_running(params->dev))
+					netif_wake_queue(params->dev);
+			}
+		}
+		params->state = RNDIS_DATA_INITIALIZED;
+	}
+}
+
 void rndis_add_hdr(struct sk_buff *skb)
 {
 	struct rndis_packet_msg_type *header;
diff --git a/drivers/usb/gadget/function/rndis.h b/drivers/usb/gadget/function/rndis.h
index 310cac3f088e..c9edf9cf12d8 100644
--- a/drivers/usb/gadget/function/rndis.h
+++ b/drivers/usb/gadget/function/rndis.h
@@ -193,13 +193,17 @@ typedef struct rndis_params
 	u8			max_pkt_per_xfer;
 	const char		*vendorDescr;
 	void			(*resp_avail)(void *v);
+	void			(*flow_ctrl_enable)(bool enable,
+			struct rndis_params *params);
+
 	void			*v;
 	struct list_head	resp_queue;
 } rndis_params;
 
 /* RNDIS Message parser and other useless functions */
 int  rndis_msg_parser(struct rndis_params *params, u8 *buf);
-struct rndis_params *rndis_register(void (*resp_avail)(void *v), void *v);
+struct rndis_params *rndis_register(void (*resp_avail)(void *v), void *v,
+	void (*flow_ctrl_enable)(bool enable, struct rndis_params *params));
 void rndis_deregister(struct rndis_params *params);
 int  rndis_set_param_dev(struct rndis_params *params, struct net_device *dev,
 			 u16 *cdc_filter);
@@ -219,5 +223,6 @@ int  rndis_signal_connect(struct rndis_params *params);
 int  rndis_signal_disconnect(struct rndis_params *params);
 int  rndis_state(struct rndis_params *params);
 extern void rndis_set_host_mac(struct rndis_params *params, const u8 *addr);
+void rndis_flow_control(struct rndis_params *params, bool enable_flow_control);
 
 #endif  /* _LINUX_RNDIS_H */