drivers: net: ethernet: qualcomm: rmnet: Initial implementation

RmNet driver provides a transport agnostic MAP (multiplexing and
aggregation protocol) support in embedded module. Module provides
virtual network devices which can be attached to any IP-mode
physical device. This will be used to provide all MAP functionality
on future hardware in a single consistent location.

Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 271 insertions, 0 deletions

diff --git a/drivers/net/ethernet/qualcomm/rmnet/rmnet_handlers.c b/drivers/net/ethernet/qualcomm/rmnet/rmnet_handlers.c
new file mode 100644
index 000000000000..7dab3bbfeda5
--- /dev/null
+++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_handlers.c
@@ -0,0 +1,271 @@
+/* Copyright (c) 2013-2017, The Linux Foundation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * RMNET Data ingress/egress handler
+ *
+ */
+
+#include <linux/netdevice.h>
+#include <linux/netdev_features.h>
+#include "rmnet_private.h"
+#include "rmnet_config.h"
+#include "rmnet_vnd.h"
+#include "rmnet_map.h"
+#include "rmnet_handlers.h"
+
+#define RMNET_IP_VERSION_4 0x40
+#define RMNET_IP_VERSION_6 0x60
+
+/* Helper Functions */
+
+static void rmnet_set_skb_proto(struct sk_buff *skb)
+{
+	switch (skb->data[0] & 0xF0) {
+	case RMNET_IP_VERSION_4:
+		skb->protocol = htons(ETH_P_IP);
+		break;
+	case RMNET_IP_VERSION_6:
+		skb->protocol = htons(ETH_P_IPV6);
+		break;
+	default:
+		skb->protocol = htons(ETH_P_MAP);
+		break;
+	}
+}
+
+/* Generic handler */
+
+static rx_handler_result_t
+rmnet_bridge_handler(struct sk_buff *skb, struct rmnet_endpoint *ep)
+{
+	if (!ep->egress_dev)
+		kfree_skb(skb);
+	else
+		rmnet_egress_handler(skb, ep);
+
+	return RX_HANDLER_CONSUMED;
+}
+
+static rx_handler_result_t
+rmnet_deliver_skb(struct sk_buff *skb, struct rmnet_endpoint *ep)
+{
+	switch (ep->rmnet_mode) {
+	case RMNET_EPMODE_NONE:
+		return RX_HANDLER_PASS;
+
+	case RMNET_EPMODE_BRIDGE:
+		return rmnet_bridge_handler(skb, ep);
+
+	case RMNET_EPMODE_VND:
+		skb_reset_transport_header(skb);
+		skb_reset_network_header(skb);
+		rmnet_vnd_rx_fixup(skb, skb->dev);
+
+		skb->pkt_type = PACKET_HOST;
+		skb_set_mac_header(skb, 0);
+		netif_receive_skb(skb);
+		return RX_HANDLER_CONSUMED;
+
+	default:
+		kfree_skb(skb);
+		return RX_HANDLER_CONSUMED;
+	}
+}
+
+static rx_handler_result_t
+rmnet_ingress_deliver_packet(struct sk_buff *skb,
+			     struct rmnet_real_dev_info *r)
+{
+	if (!r) {
+		kfree_skb(skb);
+		return RX_HANDLER_CONSUMED;
+	}
+
+	skb->dev = r->local_ep.egress_dev;
+
+	return rmnet_deliver_skb(skb, &r->local_ep);
+}
+
+/* MAP handler */
+
+static rx_handler_result_t
+__rmnet_map_ingress_handler(struct sk_buff *skb,
+			    struct rmnet_real_dev_info *r)
+{
+	struct rmnet_endpoint *ep;
+	u8 mux_id;
+	u16 len;
+
+	if (RMNET_MAP_GET_CD_BIT(skb)) {
+		if (r->ingress_data_format
+		    & RMNET_INGRESS_FORMAT_MAP_COMMANDS)
+			return rmnet_map_command(skb, r);
+
+		kfree_skb(skb);
+		return RX_HANDLER_CONSUMED;
+	}
+
+	mux_id = RMNET_MAP_GET_MUX_ID(skb);
+	len = RMNET_MAP_GET_LENGTH(skb) - RMNET_MAP_GET_PAD(skb);
+
+	if (mux_id >= RMNET_MAX_LOGICAL_EP) {
+		kfree_skb(skb);
+		return RX_HANDLER_CONSUMED;
+	}
+
+	ep = &r->muxed_ep[mux_id];
+
+	if (r->ingress_data_format & RMNET_INGRESS_FORMAT_DEMUXING)
+		skb->dev = ep->egress_dev;
+
+	/* Subtract MAP header */
+	skb_pull(skb, sizeof(struct rmnet_map_header));
+	skb_trim(skb, len);
+	rmnet_set_skb_proto(skb);
+	return rmnet_deliver_skb(skb, ep);
+}
+
+static rx_handler_result_t
+rmnet_map_ingress_handler(struct sk_buff *skb,
+			  struct rmnet_real_dev_info *r)
+{
+	struct sk_buff *skbn;
+	int rc;
+
+	if (r->ingress_data_format & RMNET_INGRESS_FORMAT_DEAGGREGATION) {
+		while ((skbn = rmnet_map_deaggregate(skb, r)) != NULL)
+			__rmnet_map_ingress_handler(skbn, r);
+
+		consume_skb(skb);
+		rc = RX_HANDLER_CONSUMED;
+	} else {
+		rc = __rmnet_map_ingress_handler(skb, r);
+	}
+
+	return rc;
+}
+
+static int rmnet_map_egress_handler(struct sk_buff *skb,
+				    struct rmnet_real_dev_info *r,
+				    struct rmnet_endpoint *ep,
+				    struct net_device *orig_dev)
+{
+	int required_headroom, additional_header_len;
+	struct rmnet_map_header *map_header;
+
+	additional_header_len = 0;
+	required_headroom = sizeof(struct rmnet_map_header);
+
+	if (skb_headroom(skb) < required_headroom) {
+		if (pskb_expand_head(skb, required_headroom, 0, GFP_KERNEL))
+			return RMNET_MAP_CONSUMED;
+	}
+
+	map_header = rmnet_map_add_map_header(skb, additional_header_len, 0);
+	if (!map_header)
+		return RMNET_MAP_CONSUMED;
+
+	if (r->egress_data_format & RMNET_EGRESS_FORMAT_MUXING) {
+		if (ep->mux_id == 0xff)
+			map_header->mux_id = 0;
+		else
+			map_header->mux_id = ep->mux_id;
+	}
+
+	skb->protocol = htons(ETH_P_MAP);
+
+	return RMNET_MAP_SUCCESS;
+}
+
+/* Ingress / Egress Entry Points */
+
+/* Processes packet as per ingress data format for receiving device. Logical
+ * endpoint is determined from packet inspection. Packet is then sent to the
+ * egress device listed in the logical endpoint configuration.
+ */
+rx_handler_result_t rmnet_rx_handler(struct sk_buff **pskb)
+{
+	struct rmnet_real_dev_info *r;
+	struct sk_buff *skb = *pskb;
+	struct net_device *dev;
+	int rc;
+
+	if (!skb)
+		return RX_HANDLER_CONSUMED;
+
+	dev = skb->dev;
+	r = rmnet_get_real_dev_info(dev);
+
+	if (r->ingress_data_format & RMNET_INGRESS_FORMAT_MAP) {
+		rc = rmnet_map_ingress_handler(skb, r);
+	} else {
+		switch (ntohs(skb->protocol)) {
+		case ETH_P_MAP:
+			if (r->local_ep.rmnet_mode ==
+				RMNET_EPMODE_BRIDGE) {
+				rc = rmnet_ingress_deliver_packet(skb, r);
+			} else {
+				kfree_skb(skb);
+				rc = RX_HANDLER_CONSUMED;
+			}
+			break;
+
+		case ETH_P_IP:
+		case ETH_P_IPV6:
+			rc = rmnet_ingress_deliver_packet(skb, r);
+			break;
+
+		default:
+			rc = RX_HANDLER_PASS;
+		}
+	}
+
+	return rc;
+}
+
+/* Modifies packet as per logical endpoint configuration and egress data format
+ * for egress device configured in logical endpoint. Packet is then transmitted
+ * on the egress device.
+ */
+void rmnet_egress_handler(struct sk_buff *skb,
+			  struct rmnet_endpoint *ep)
+{
+	struct rmnet_real_dev_info *r;
+	struct net_device *orig_dev;
+
+	orig_dev = skb->dev;
+	skb->dev = ep->egress_dev;
+
+	r = rmnet_get_real_dev_info(skb->dev);
+	if (!r) {
+		kfree_skb(skb);
+		return;
+	}
+
+	if (r->egress_data_format & RMNET_EGRESS_FORMAT_MAP) {
+		switch (rmnet_map_egress_handler(skb, r, ep, orig_dev)) {
+		case RMNET_MAP_CONSUMED:
+			return;
+
+		case RMNET_MAP_SUCCESS:
+			break;
+
+		default:
+			kfree_skb(skb);
+			return;
+		}
+	}
+
+	if (ep->rmnet_mode == RMNET_EPMODE_VND)
+		rmnet_vnd_tx_fixup(skb, orig_dev);
+
+	dev_queue_xmit(skb);
+}