[net-next,v4,5/5] net: mhi: Add mbim proto

diff --git a/drivers/net/mhi/Makefile b/drivers/net/mhi/Makefile
index 0acf989..f71b9f8 100644
--- a/drivers/net/mhi/Makefile
+++ b/drivers/net/mhi/Makefile
@@ -1,3 +1,3 @@ 
 obj-$(CONFIG_MHI_NET) += mhi_net.o
 
-mhi_net-y := net.o
+mhi_net-y := net.o proto_mbim.o
diff --git a/drivers/net/mhi/mhi.h b/drivers/net/mhi/mhi.h
index 82210e0..12e7407 100644
--- a/drivers/net/mhi/mhi.h
+++ b/drivers/net/mhi/mhi.h
@@ -28,6 +28,7 @@  struct mhi_net_dev {
 	struct delayed_work rx_refill;
 	struct mhi_net_stats stats;
 	u32 rx_queue_sz;
+	int msg_enable;
 };
 
 struct mhi_net_proto {
@@ -35,3 +36,5 @@  struct mhi_net_proto {
 	struct sk_buff * (*tx_fixup)(struct mhi_net_dev *mhi_netdev, struct sk_buff *skb);
 	void (*rx)(struct mhi_net_dev *mhi_netdev, struct sk_buff *skb);
 };
+
+extern const struct mhi_net_proto proto_mbim;
diff --git a/drivers/net/mhi/net.c b/drivers/net/mhi/net.c
index 44cbfb3..f599608 100644
--- a/drivers/net/mhi/net.c
+++ b/drivers/net/mhi/net.c
@@ -373,11 +373,18 @@  static const struct mhi_device_info mhi_swip0 = {
 	.netname = "mhi_swip%d",
 };
 
+static const struct mhi_device_info mhi_hwip0_mbim = {
+	.netname = "mhi_mbim%d",
+	.proto = &proto_mbim,
+};
+
 static const struct mhi_device_id mhi_net_id_table[] = {
 	/* Hardware accelerated data PATH (to modem IPA), protocol agnostic */
 	{ .chan = "IP_HW0", .driver_data = (kernel_ulong_t)&mhi_hwip0 },
 	/* Software data PATH (to modem CPU) */
 	{ .chan = "IP_SW0", .driver_data = (kernel_ulong_t)&mhi_swip0 },
+	/* Hardware accelerated data PATH (to modem IPA), MBIM protocol */
+	{ .chan = "IP_HW0_MBIM", .driver_data = (kernel_ulong_t)&mhi_hwip0_mbim },
 	{}
 };
 MODULE_DEVICE_TABLE(mhi, mhi_net_id_table);
diff --git a/drivers/net/mhi/proto_mbim.c b/drivers/net/mhi/proto_mbim.c
new file mode 100644
index 0000000..fb9a4f1
--- /dev/null
+++ b/drivers/net/mhi/proto_mbim.c
@@ -0,0 +1,293 @@ 
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* MHI Network driver - Network over MHI bus
+ *
+ * Copyright (C) 2021 Linaro Ltd <loic.poulain@linaro.org>
+ *
+ * This driver copy some code from cdc_ncm, which is:
+ * Copyright (C) ST-Ericsson 2010-2012
+ * and cdc_mbim, which is:
+ * Copyright (c) 2012  Smith Micro Software, Inc.
+ * Copyright (c) 2012  Bjørn Mork <bjorn@mork.no>
+ *
+ */
+
+#include <linux/ethtool.h>
+#include <linux/if_vlan.h>
+#include <linux/ip.h>
+#include <linux/mii.h>
+#include <linux/netdevice.h>
+#include <linux/skbuff.h>
+#include <linux/usb.h>
+#include <linux/usb/cdc.h>
+#include <linux/usb/usbnet.h>
+#include <linux/usb/cdc_ncm.h>
+
+#include "mhi.h"
+
+#define MBIM_NDP16_SIGN_MASK cpu_to_le32(0x00ffffff)
+
+struct mbim_context {
+	u16 rx_seq;
+	u16 tx_seq;
+};
+
+static void __mbim_length_errors_inc(struct mhi_net_dev *dev)
+{
+	u64_stats_update_begin(&dev->stats.rx_syncp);
+	u64_stats_inc(&dev->stats.rx_length_errors);
+	u64_stats_update_end(&dev->stats.rx_syncp);
+}
+
+static void __mbim_errors_inc(struct mhi_net_dev *dev)
+{
+	u64_stats_update_begin(&dev->stats.rx_syncp);
+	u64_stats_inc(&dev->stats.rx_errors);
+	u64_stats_update_end(&dev->stats.rx_syncp);
+}
+
+static int mbim_rx_verify_nth16(struct sk_buff *skb)
+{
+	struct mhi_net_dev *dev = netdev_priv(skb->dev);
+	struct mbim_context *ctx = dev->proto_data;
+	struct usb_cdc_ncm_nth16 *nth16;
+	int len;
+
+	if (skb->len < sizeof(struct usb_cdc_ncm_nth16) +
+			sizeof(struct usb_cdc_ncm_ndp16)) {
+		netif_dbg(dev, rx_err, dev->ndev, "frame too short\n");
+		__mbim_length_errors_inc(dev);
+		return -EINVAL;
+	}
+
+	nth16 = (struct usb_cdc_ncm_nth16 *)skb->data;
+
+	if (nth16->dwSignature != cpu_to_le32(USB_CDC_NCM_NTH16_SIGN)) {
+		netif_dbg(dev, rx_err, dev->ndev,
+			  "invalid NTH16 signature <%#010x>\n",
+			  le32_to_cpu(nth16->dwSignature));
+		__mbim_errors_inc(dev);
+		return -EINVAL;
+	}
+
+	/* No limit on the block length, except the size of the data pkt */
+	len = le16_to_cpu(nth16->wBlockLength);
+	if (len > skb->len) {
+		netif_dbg(dev, rx_err, dev->ndev,
+			  "NTB does not fit into the skb %u/%u\n", len,
+			  skb->len);
+		__mbim_length_errors_inc(dev);
+		return -EINVAL;
+	}
+
+	if (ctx->rx_seq + 1 != le16_to_cpu(nth16->wSequence) &&
+	    (ctx->rx_seq || le16_to_cpu(nth16->wSequence)) &&
+	    !(ctx->rx_seq == 0xffff && !le16_to_cpu(nth16->wSequence))) {
+		netif_dbg(dev, rx_err, dev->ndev,
+			  "sequence number glitch prev=%d curr=%d\n",
+			  ctx->rx_seq, le16_to_cpu(nth16->wSequence));
+	}
+	ctx->rx_seq = le16_to_cpu(nth16->wSequence);
+
+	return le16_to_cpu(nth16->wNdpIndex);
+}
+
+static int mbim_rx_verify_ndp16(struct sk_buff *skb, int ndpoffset)
+{
+	struct mhi_net_dev *dev = netdev_priv(skb->dev);
+	struct usb_cdc_ncm_ndp16 *ndp16;
+	int ret;
+
+	if (ndpoffset + sizeof(struct usb_cdc_ncm_ndp16) > skb->len) {
+		netif_dbg(dev, rx_err, dev->ndev, "invalid NDP offset  <%u>\n",
+			  ndpoffset);
+		return -EINVAL;
+	}
+
+	ndp16 = (struct usb_cdc_ncm_ndp16 *)(skb->data + ndpoffset);
+
+	if (le16_to_cpu(ndp16->wLength) < USB_CDC_NCM_NDP16_LENGTH_MIN) {
+		netif_dbg(dev, rx_err, dev->ndev, "invalid DPT16 length <%u>\n",
+			  le16_to_cpu(ndp16->wLength));
+		return -EINVAL;
+	}
+
+	ret = ((le16_to_cpu(ndp16->wLength) - sizeof(struct usb_cdc_ncm_ndp16))
+			/ sizeof(struct usb_cdc_ncm_dpe16));
+	ret--; /* Last entry is always a NULL terminator */
+
+	if (sizeof(struct usb_cdc_ncm_ndp16) +
+	     ret * sizeof(struct usb_cdc_ncm_dpe16) > skb->len) {
+		netif_dbg(dev, rx_err, dev->ndev,
+			  "Invalid nframes = %d\n", ret);
+		return -EINVAL;
+	}
+
+	return ret;
+}
+
+static void mbim_rx(struct mhi_net_dev *mhi_netdev, struct sk_buff *skb)
+{
+	struct net_device *ndev = mhi_netdev->ndev;
+	int ndpoffset;
+
+	if (skb_linearize(skb))
+		goto error;
+
+	/* Check NTB header and retrieve first NDP offset */
+	ndpoffset = mbim_rx_verify_nth16(skb);
+	if (ndpoffset < 0) {
+		net_err_ratelimited("%s: Incorrect NTB header\n", ndev->name);
+		goto error;
+	}
+
+	/* Process each NDP */
+	while (1) {
+		struct usb_cdc_ncm_ndp16 *ndp16;
+		struct usb_cdc_ncm_dpe16 *dpe16;
+		int nframes, n;
+
+		/* Check NDP header and retrieve number of datagrams */
+		nframes = mbim_rx_verify_ndp16(skb, ndpoffset);
+		if (nframes < 0) {
+			net_err_ratelimited("%s: Incorrect NDP16\n", ndev->name);
+			__mbim_length_errors_inc(mhi_netdev);
+			goto error;
+		}
+
+		 /* Only IP data type supported, no DSS in MHI context */
+		ndp16 = (struct usb_cdc_ncm_ndp16 *)(skb->data + ndpoffset);
+		if ((ndp16->dwSignature & MBIM_NDP16_SIGN_MASK)
+					!= USB_CDC_MBIM_NDP16_IPS_SIGN) {
+			net_err_ratelimited("%s: Unsupported NDP type\n", ndev->name);
+			__mbim_errors_inc(mhi_netdev);
+			goto next_ndp;
+		}
+
+		/* Only primary IP session 0 (0x00) supported for now */
+		if (ndp16->dwSignature & ~MBIM_NDP16_SIGN_MASK) {
+			net_err_ratelimited("%s: bad packet session\n", ndev->name);
+			__mbim_errors_inc(mhi_netdev);
+			goto next_ndp;
+		}
+
+		/* de-aggregate and deliver IP packets */
+		dpe16 = ndp16->dpe16;
+		for (n = 0; n < nframes; n++, dpe16++) {
+			u16 dgram_offset = le16_to_cpu(dpe16->wDatagramIndex);
+			u16 dgram_len = le16_to_cpu(dpe16->wDatagramLength);
+			struct sk_buff *skbn;
+
+			if (!dgram_offset || !dgram_len)
+				break; /* null terminator */
+
+			skbn = netdev_alloc_skb(ndev, dgram_len);
+			if (!skbn)
+				continue;
+
+			skb_put(skbn, dgram_len);
+			memcpy(skbn->data, skb->data + dgram_offset, dgram_len);
+
+			switch (skbn->data[0] & 0xf0) {
+			case 0x40:
+				skbn->protocol = htons(ETH_P_IP);
+				break;
+			case 0x60:
+				skbn->protocol = htons(ETH_P_IPV6);
+				break;
+			default:
+				net_err_ratelimited("%s: unknown protocol\n",
+						    ndev->name);
+				__mbim_errors_inc(mhi_netdev);
+				dev_kfree_skb_any(skbn);
+				continue;
+			}
+
+			netif_rx(skbn);
+		}
+next_ndp:
+		/* Other NDP to process? */
+		ndpoffset = le16_to_cpu(ndp16->wNextNdpIndex);
+		if (!ndpoffset)
+			break;
+	}
+
+	/* free skb */
+	dev_consume_skb_any(skb);
+	return;
+error:
+	dev_kfree_skb_any(skb);
+}
+
+struct mbim_tx_hdr {
+	struct usb_cdc_ncm_nth16 nth16;
+	struct usb_cdc_ncm_ndp16 ndp16;
+	struct usb_cdc_ncm_dpe16 dpe16[2];
+} __packed;
+
+static struct sk_buff *mbim_tx_fixup(struct mhi_net_dev *mhi_netdev,
+				     struct sk_buff *skb)
+{
+	struct mbim_context *ctx = mhi_netdev->proto_data;
+	unsigned int dgram_size = skb->len;
+	struct usb_cdc_ncm_nth16 *nth16;
+	struct usb_cdc_ncm_ndp16 *ndp16;
+	struct mbim_tx_hdr *mbim_hdr;
+
+	/* For now, this is a partial implementation of CDC MBIM, only one NDP
+	 * is sent, containing the IP packet (no aggregation).
+	 */
+
+	/* Ensure we have enough headroom for crafting MBIM header */
+	if (skb_cow_head(skb, sizeof(struct mbim_tx_hdr))) {
+		dev_kfree_skb_any(skb);
+		return NULL;
+	}
+
+	mbim_hdr = skb_push(skb, sizeof(struct mbim_tx_hdr));
+
+	/* Fill NTB header */
+	nth16 = &mbim_hdr->nth16;
+	nth16->dwSignature = cpu_to_le32(USB_CDC_NCM_NTH16_SIGN);
+	nth16->wHeaderLength = cpu_to_le16(sizeof(struct usb_cdc_ncm_nth16));
+	nth16->wSequence = cpu_to_le16(ctx->tx_seq++);
+	nth16->wBlockLength = cpu_to_le16(skb->len);
+	nth16->wNdpIndex = cpu_to_le16(sizeof(struct usb_cdc_ncm_nth16));
+
+	/* Fill the unique NDP */
+	ndp16 = &mbim_hdr->ndp16;
+	ndp16->dwSignature = cpu_to_le32(USB_CDC_MBIM_NDP16_IPS_SIGN);
+	ndp16->wLength = cpu_to_le16(sizeof(struct usb_cdc_ncm_ndp16)
+					+ sizeof(struct usb_cdc_ncm_dpe16) * 2);
+	ndp16->wNextNdpIndex = 0;
+
+	/* Datagram follows the mbim header */
+	ndp16->dpe16[0].wDatagramIndex = cpu_to_le16(sizeof(struct mbim_tx_hdr));
+	ndp16->dpe16[0].wDatagramLength = cpu_to_le16(dgram_size);
+
+	/* null termination */
+	ndp16->dpe16[1].wDatagramIndex = 0;
+	ndp16->dpe16[1].wDatagramLength = 0;
+
+	return skb;
+}
+
+static int mbim_init(struct mhi_net_dev *mhi_netdev)
+{
+	struct net_device *ndev = mhi_netdev->ndev;
+
+	mhi_netdev->proto_data = devm_kzalloc(&ndev->dev,
+					      sizeof(struct mbim_context),
+					      GFP_KERNEL);
+	if (!mhi_netdev->proto_data)
+		return -ENOMEM;
+
+	ndev->needed_headroom = sizeof(struct mbim_tx_hdr);
+
+	return 0;
+}
+
+const struct mhi_net_proto proto_mbim = {
+	.init = mbim_init,
+	.rx = mbim_rx,
+	.tx_fixup = mbim_tx_fixup,
+};