net: rmnet_data: Add snapshot of rmnet_data driver

This is a snapshot of the rmnet_data driver taken as of msm-4.4.
commit 5da00923b1544ba ("rmnet_data: Changing format specifier to
%pK").

Additionally, fix some style issues reported by checkpatch.

CRs-Fixed: 1078373
Change-Id: Idb2df22e61803e04a01db64ea5e9d1e93ae92e09
Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>
diff --git a/net/rmnet_data/rmnet_map_command.c b/net/rmnet_data/rmnet_map_command.c
new file mode 100644
index 0000000..306b6fb
--- /dev/null
+++ b/net/rmnet_data/rmnet_map_command.c
@@ -0,0 +1,196 @@
+/* Copyright (c) 2013-2016, 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.
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/skbuff.h>
+#include <linux/netdevice.h>
+#include <linux/rmnet_data.h>
+#include <linux/net_map.h>
+#include <net/pkt_sched.h>
+#include <net/rmnet_config.h>
+#include "rmnet_data_config.h"
+#include "rmnet_map.h"
+#include "rmnet_data_private.h"
+#include "rmnet_data_vnd.h"
+#include "rmnet_data_stats.h"
+
+RMNET_LOG_MODULE(RMNET_DATA_LOGMASK_MAPC);
+
+unsigned long int rmnet_map_command_stats[RMNET_MAP_COMMAND_ENUM_LENGTH];
+module_param_array(rmnet_map_command_stats, ulong, 0, 0444);
+MODULE_PARM_DESC(rmnet_map_command_stats, "MAP command statistics");
+
+/* rmnet_map_do_flow_control() - Process MAP flow control command
+ * @skb: Socket buffer containing the MAP flow control message
+ * @config: Physical end-point configuration of ingress device
+ * @enable: boolean for enable/disable
+ *
+ * Process in-band MAP flow control messages. Assumes mux ID is mapped to a
+ * RmNet Data vitrual network device.
+ *
+ * Return:
+ *      - RMNET_MAP_COMMAND_UNSUPPORTED on any error
+ *      - RMNET_MAP_COMMAND_ACK on success
+ */
+static uint8_t rmnet_map_do_flow_control(struct sk_buff *skb,
+					 struct rmnet_phys_ep_config *config,
+					 int enable)
+{
+	struct rmnet_map_control_command_s *cmd;
+	struct net_device *vnd;
+	struct rmnet_logical_ep_conf_s *ep;
+	u8 mux_id;
+	u16  ip_family;
+	u16  fc_seq;
+	u32  qos_id;
+	int r;
+
+	if (unlikely(!skb || !config))
+		return RX_HANDLER_CONSUMED;
+
+	mux_id = RMNET_MAP_GET_MUX_ID(skb);
+	cmd = RMNET_MAP_GET_CMD_START(skb);
+
+	if (mux_id >= RMNET_DATA_MAX_LOGICAL_EP) {
+		LOGD("Got packet on %s with bad mux id %d",
+		     skb->dev->name, mux_id);
+		rmnet_kfree_skb(skb, RMNET_STATS_SKBFREE_MAPC_BAD_MUX);
+		return RX_HANDLER_CONSUMED;
+	}
+
+	ep = &config->muxed_ep[mux_id];
+
+	if (!ep->refcount) {
+		LOGD("Packet on %s:%d; has no logical endpoint config",
+		     skb->dev->name, mux_id);
+
+		rmnet_kfree_skb(skb, RMNET_STATS_SKBFREE_MAPC_MUX_NO_EP);
+			return RX_HANDLER_CONSUMED;
+	}
+
+	vnd = ep->egress_dev;
+
+	ip_family = cmd->flow_control.ip_family;
+	fc_seq = ntohs(cmd->flow_control.flow_control_seq_num);
+	qos_id = ntohl(cmd->flow_control.qos_id);
+
+	/* Ignore the ip family and pass the sequence number for both v4 and v6
+	 * sequence. User space does not support creating dedicated flows for
+	 * the 2 protocols
+	 */
+	r = rmnet_vnd_do_flow_control(vnd, qos_id, fc_seq, fc_seq, enable);
+	LOGD("dev:%s, qos_id:0x%08X, ip_family:%hd, fc_seq %hd, en:%d",
+	     skb->dev->name, qos_id, ip_family & 3, fc_seq, enable);
+
+	if (r) {
+		rmnet_kfree_skb(skb, RMNET_STATS_SKBFREE_MAPC_UNSUPPORTED);
+		return RMNET_MAP_COMMAND_UNSUPPORTED;
+	} else {
+		return RMNET_MAP_COMMAND_ACK;
+	}
+}
+
+/* rmnet_map_send_ack() - Send N/ACK message for MAP commands
+ * @skb: Socket buffer containing the MAP command message
+ * @type: N/ACK message selector
+ * @config: Physical end-point configuration of ingress device
+ *
+ * skb is modified to contain the message type selector. The message is then
+ * transmitted on skb->dev. Note that this function grabs global Tx lock on
+ * skb->dev for latency reasons.
+ *
+ * Return:
+ *      - void
+ */
+static void rmnet_map_send_ack(struct sk_buff *skb,
+			       unsigned char type,
+			       struct rmnet_phys_ep_config *config)
+{
+	struct rmnet_map_control_command_s *cmd;
+	int xmit_status;
+
+	if (unlikely(!skb))
+		return;
+
+	skb->protocol = htons(ETH_P_MAP);
+
+	if ((config->ingress_data_format & RMNET_INGRESS_FORMAT_MAP_CKSUMV3) ||
+	    (config->ingress_data_format & RMNET_INGRESS_FORMAT_MAP_CKSUMV4)) {
+		if (unlikely(skb->len < (sizeof(struct rmnet_map_header_s) +
+		    + RMNET_MAP_GET_LENGTH(skb)
+		    + sizeof(struct rmnet_map_dl_checksum_trailer_s)))) {
+			rmnet_stats_dl_checksum(
+			  RMNET_MAP_CHECKSUM_ERR_BAD_BUFFER);
+			return;
+		}
+
+		skb_trim(skb, skb->len -
+			 sizeof(struct rmnet_map_dl_checksum_trailer_s));
+	}
+
+	cmd = RMNET_MAP_GET_CMD_START(skb);
+	cmd->cmd_type = type & 0x03;
+
+	netif_tx_lock(skb->dev);
+	xmit_status = skb->dev->netdev_ops->ndo_start_xmit(skb, skb->dev);
+	netif_tx_unlock(skb->dev);
+
+	LOGD("MAP command ACK=%hhu sent with rc: %d", type & 0x03, xmit_status);
+}
+
+/* rmnet_map_command() - Entry point for handling MAP commands
+ * @skb: Socket buffer containing the MAP command message
+ * @config: Physical end-point configuration of ingress device
+ *
+ * Process MAP command frame and send N/ACK message as appropriate. Message cmd
+ * name is decoded here and appropriate handler is called.
+ *
+ * Return:
+ *      - RX_HANDLER_CONSUMED. Command frames are always consumed.
+ */
+rx_handler_result_t rmnet_map_command(struct sk_buff *skb,
+				      struct rmnet_phys_ep_config *config)
+{
+	struct rmnet_map_control_command_s *cmd;
+	unsigned char command_name;
+	unsigned char rc = 0;
+
+	if (unlikely(!skb))
+		return RX_HANDLER_CONSUMED;
+
+	cmd = RMNET_MAP_GET_CMD_START(skb);
+	command_name = cmd->command_name;
+
+	if (command_name < RMNET_MAP_COMMAND_ENUM_LENGTH)
+		rmnet_map_command_stats[command_name]++;
+
+	switch (command_name) {
+	case RMNET_MAP_COMMAND_FLOW_ENABLE:
+		rc = rmnet_map_do_flow_control(skb, config, 1);
+		break;
+
+	case RMNET_MAP_COMMAND_FLOW_DISABLE:
+		rc = rmnet_map_do_flow_control(skb, config, 0);
+		break;
+
+	default:
+		rmnet_map_command_stats[RMNET_MAP_COMMAND_UNKNOWN]++;
+		LOGM("Uknown MAP command: %d", command_name);
+		rc = RMNET_MAP_COMMAND_UNSUPPORTED;
+		rmnet_kfree_skb(skb, RMNET_STATS_SKBFREE_MAPC_UNSUPPORTED);
+		break;
+	}
+	if (rc == RMNET_MAP_COMMAND_ACK)
+		rmnet_map_send_ack(skb, rc, config);
+	return RX_HANDLER_CONSUMED;
+}