[linux-2.6-block.git] / drivers / net / mhi_net.c

// SPDX-License-Identifier: GPL-2.0-or-later
/* MHI Network driver - Network over MHI bus
 *
 * Copyright (C) 2020 Linaro Ltd <loic.poulain@linaro.org>
 */

#include <linux/if_arp.h>
#include <linux/mhi.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <linux/u64_stats_sync.h>

#define MHI_NET_MIN_MTU		ETH_MIN_MTU
#define MHI_NET_MAX_MTU		0xffff
#define MHI_NET_DEFAULT_MTU	0x4000

struct mhi_net_stats {
	u64_stats_t rx_packets;
	u64_stats_t rx_bytes;
	u64_stats_t rx_errors;
	u64_stats_t tx_packets;
	u64_stats_t tx_bytes;
	u64_stats_t tx_errors;
	u64_stats_t tx_dropped;
	struct u64_stats_sync tx_syncp;
	struct u64_stats_sync rx_syncp;
};

struct mhi_net_dev {
	struct mhi_device *mdev;
	struct net_device *ndev;
	struct sk_buff *skbagg_head;
	struct sk_buff *skbagg_tail;
	struct delayed_work rx_refill;
	struct mhi_net_stats stats;
	u32 rx_queue_sz;
	int msg_enable;
	unsigned int mru;
};

struct mhi_device_info {
	const char *netname;
};

static int mhi_ndo_open(struct net_device *ndev)
{
	struct mhi_net_dev *mhi_netdev = netdev_priv(ndev);

	/* Feed the rx buffer pool */
	schedule_delayed_work(&mhi_netdev->rx_refill, 0);

	/* Carrier is established via out-of-band channel (e.g. qmi) */
	netif_carrier_on(ndev);

	netif_start_queue(ndev);

	return 0;
}

static int mhi_ndo_stop(struct net_device *ndev)
{
	struct mhi_net_dev *mhi_netdev = netdev_priv(ndev);

	netif_stop_queue(ndev);
	netif_carrier_off(ndev);
	cancel_delayed_work_sync(&mhi_netdev->rx_refill);

	return 0;
}

static netdev_tx_t mhi_ndo_xmit(struct sk_buff *skb, struct net_device *ndev)
{
	struct mhi_net_dev *mhi_netdev = netdev_priv(ndev);
	struct mhi_device *mdev = mhi_netdev->mdev;
	int err;

	err = mhi_queue_skb(mdev, DMA_TO_DEVICE, skb, skb->len, MHI_EOT);
	if (unlikely(err)) {
		net_err_ratelimited("%s: Failed to queue TX buf (%d)\n",
				    ndev->name, err);
		dev_kfree_skb_any(skb);
		goto exit_drop;
	}

	if (mhi_queue_is_full(mdev, DMA_TO_DEVICE))
		netif_stop_queue(ndev);

	return NETDEV_TX_OK;

exit_drop:
	u64_stats_update_begin(&mhi_netdev->stats.tx_syncp);
	u64_stats_inc(&mhi_netdev->stats.tx_dropped);
	u64_stats_update_end(&mhi_netdev->stats.tx_syncp);

	return NETDEV_TX_OK;
}

static void mhi_ndo_get_stats64(struct net_device *ndev,
				struct rtnl_link_stats64 *stats)
{
	struct mhi_net_dev *mhi_netdev = netdev_priv(ndev);
	unsigned int start;

	do {
		start = u64_stats_fetch_begin(&mhi_netdev->stats.rx_syncp);
		stats->rx_packets = u64_stats_read(&mhi_netdev->stats.rx_packets);
		stats->rx_bytes = u64_stats_read(&mhi_netdev->stats.rx_bytes);
		stats->rx_errors = u64_stats_read(&mhi_netdev->stats.rx_errors);
	} while (u64_stats_fetch_retry(&mhi_netdev->stats.rx_syncp, start));

	do {
		start = u64_stats_fetch_begin(&mhi_netdev->stats.tx_syncp);
		stats->tx_packets = u64_stats_read(&mhi_netdev->stats.tx_packets);
		stats->tx_bytes = u64_stats_read(&mhi_netdev->stats.tx_bytes);
		stats->tx_errors = u64_stats_read(&mhi_netdev->stats.tx_errors);
		stats->tx_dropped = u64_stats_read(&mhi_netdev->stats.tx_dropped);
	} while (u64_stats_fetch_retry(&mhi_netdev->stats.tx_syncp, start));
}

static const struct net_device_ops mhi_netdev_ops = {
	.ndo_open               = mhi_ndo_open,
	.ndo_stop               = mhi_ndo_stop,
	.ndo_start_xmit         = mhi_ndo_xmit,
	.ndo_get_stats64	= mhi_ndo_get_stats64,
};

static void mhi_net_setup(struct net_device *ndev)
{
	ndev->header_ops = NULL;  /* No header */
	ndev->type = ARPHRD_RAWIP;
	ndev->hard_header_len = 0;
	ndev->addr_len = 0;
	ndev->flags = IFF_POINTOPOINT | IFF_NOARP;
	ndev->netdev_ops = &mhi_netdev_ops;
	ndev->mtu = MHI_NET_DEFAULT_MTU;
	ndev->min_mtu = MHI_NET_MIN_MTU;
	ndev->max_mtu = MHI_NET_MAX_MTU;
	ndev->tx_queue_len = 1000;
}

static struct sk_buff *mhi_net_skb_agg(struct mhi_net_dev *mhi_netdev,
				       struct sk_buff *skb)
{
	struct sk_buff *head = mhi_netdev->skbagg_head;
	struct sk_buff *tail = mhi_netdev->skbagg_tail;

	/* This is non-paged skb chaining using frag_list */
	if (!head) {
		mhi_netdev->skbagg_head = skb;
		return skb;
	}

	if (!skb_shinfo(head)->frag_list)
		skb_shinfo(head)->frag_list = skb;
	else
		tail->next = skb;

	head->len += skb->len;
	head->data_len += skb->len;
	head->truesize += skb->truesize;

	mhi_netdev->skbagg_tail = skb;

	return mhi_netdev->skbagg_head;
}

static void mhi_net_dl_callback(struct mhi_device *mhi_dev,
				struct mhi_result *mhi_res)
{
	struct mhi_net_dev *mhi_netdev = dev_get_drvdata(&mhi_dev->dev);
	struct sk_buff *skb = mhi_res->buf_addr;
	int free_desc_count;

	free_desc_count = mhi_get_free_desc_count(mhi_dev, DMA_FROM_DEVICE);

	if (unlikely(mhi_res->transaction_status)) {
		switch (mhi_res->transaction_status) {
		case -EOVERFLOW:
			/* Packet can not fit in one MHI buffer and has been
			 * split over multiple MHI transfers, do re-aggregation.
			 * That usually means the device side MTU is larger than
			 * the host side MTU/MRU. Since this is not optimal,
			 * print a warning (once).
			 */
			netdev_warn_once(mhi_netdev->ndev,
					 "Fragmented packets received, fix MTU?\n");
			skb_put(skb, mhi_res->bytes_xferd);
			mhi_net_skb_agg(mhi_netdev, skb);
			break;
		case -ENOTCONN:
			/* MHI layer stopping/resetting the DL channel */
			dev_kfree_skb_any(skb);
			return;
		default:
			/* Unknown error, simply drop */
			dev_kfree_skb_any(skb);
			u64_stats_update_begin(&mhi_netdev->stats.rx_syncp);
			u64_stats_inc(&mhi_netdev->stats.rx_errors);
			u64_stats_update_end(&mhi_netdev->stats.rx_syncp);
		}
	} else {
		skb_put(skb, mhi_res->bytes_xferd);

		if (mhi_netdev->skbagg_head) {
			/* Aggregate the final fragment */
			skb = mhi_net_skb_agg(mhi_netdev, skb);
			mhi_netdev->skbagg_head = NULL;
		}

		switch (skb->data[0] & 0xf0) {
		case 0x40:
			skb->protocol = htons(ETH_P_IP);
			break;
		case 0x60:
			skb->protocol = htons(ETH_P_IPV6);
			break;
		default:
			skb->protocol = htons(ETH_P_MAP);
			break;
		}

		u64_stats_update_begin(&mhi_netdev->stats.rx_syncp);
		u64_stats_inc(&mhi_netdev->stats.rx_packets);
		u64_stats_add(&mhi_netdev->stats.rx_bytes, skb->len);
		u64_stats_update_end(&mhi_netdev->stats.rx_syncp);
		__netif_rx(skb);
	}

	/* Refill if RX buffers queue becomes low */
	if (free_desc_count >= mhi_netdev->rx_queue_sz / 2)
		schedule_delayed_work(&mhi_netdev->rx_refill, 0);
}

static void mhi_net_ul_callback(struct mhi_device *mhi_dev,
				struct mhi_result *mhi_res)
{
	struct mhi_net_dev *mhi_netdev = dev_get_drvdata(&mhi_dev->dev);
	struct net_device *ndev = mhi_netdev->ndev;
	struct mhi_device *mdev = mhi_netdev->mdev;
	struct sk_buff *skb = mhi_res->buf_addr;

	/* Hardware has consumed the buffer, so free the skb (which is not
	 * freed by the MHI stack) and perform accounting.
	 */
	dev_consume_skb_any(skb);

	u64_stats_update_begin(&mhi_netdev->stats.tx_syncp);
	if (unlikely(mhi_res->transaction_status)) {
		/* MHI layer stopping/resetting the UL channel */
		if (mhi_res->transaction_status == -ENOTCONN) {
			u64_stats_update_end(&mhi_netdev->stats.tx_syncp);
			return;
		}

		u64_stats_inc(&mhi_netdev->stats.tx_errors);
	} else {
		u64_stats_inc(&mhi_netdev->stats.tx_packets);
		u64_stats_add(&mhi_netdev->stats.tx_bytes, mhi_res->bytes_xferd);
	}
	u64_stats_update_end(&mhi_netdev->stats.tx_syncp);

	if (netif_queue_stopped(ndev) && !mhi_queue_is_full(mdev, DMA_TO_DEVICE))
		netif_wake_queue(ndev);
}

static void mhi_net_rx_refill_work(struct work_struct *work)
{
	struct mhi_net_dev *mhi_netdev = container_of(work, struct mhi_net_dev,
						      rx_refill.work);
	struct net_device *ndev = mhi_netdev->ndev;
	struct mhi_device *mdev = mhi_netdev->mdev;
	struct sk_buff *skb;
	unsigned int size;
	int err;

	size = mhi_netdev->mru ? mhi_netdev->mru : READ_ONCE(ndev->mtu);

	while (!mhi_queue_is_full(mdev, DMA_FROM_DEVICE)) {
		skb = netdev_alloc_skb(ndev, size);
		if (unlikely(!skb))
			break;

		err = mhi_queue_skb(mdev, DMA_FROM_DEVICE, skb, size, MHI_EOT);
		if (unlikely(err)) {
			net_err_ratelimited("%s: Failed to queue RX buf (%d)\n",
					    ndev->name, err);
			kfree_skb(skb);
			break;
		}

		/* Do not hog the CPU if rx buffers are consumed faster than
		 * queued (unlikely).
		 */
		cond_resched();
	}

	/* If we're still starved of rx buffers, reschedule later */
	if (mhi_get_free_desc_count(mdev, DMA_FROM_DEVICE) == mhi_netdev->rx_queue_sz)
		schedule_delayed_work(&mhi_netdev->rx_refill, HZ / 2);
}

static int mhi_net_newlink(struct mhi_device *mhi_dev, struct net_device *ndev)
{
	struct mhi_net_dev *mhi_netdev;
	int err;

	mhi_netdev = netdev_priv(ndev);

	dev_set_drvdata(&mhi_dev->dev, mhi_netdev);
	mhi_netdev->ndev = ndev;
	mhi_netdev->mdev = mhi_dev;
	mhi_netdev->skbagg_head = NULL;
	mhi_netdev->mru = mhi_dev->mhi_cntrl->mru;

	INIT_DELAYED_WORK(&mhi_netdev->rx_refill, mhi_net_rx_refill_work);
	u64_stats_init(&mhi_netdev->stats.rx_syncp);
	u64_stats_init(&mhi_netdev->stats.tx_syncp);

	/* Start MHI channels */
	err = mhi_prepare_for_transfer(mhi_dev);
	if (err)
		return err;

	/* Number of transfer descriptors determines size of the queue */
	mhi_netdev->rx_queue_sz = mhi_get_free_desc_count(mhi_dev, DMA_FROM_DEVICE);

	err = register_netdev(ndev);
	if (err)
		return err;

	return 0;
}

static void mhi_net_dellink(struct mhi_device *mhi_dev, struct net_device *ndev)
{
	struct mhi_net_dev *mhi_netdev = netdev_priv(ndev);

	unregister_netdev(ndev);

	mhi_unprepare_from_transfer(mhi_dev);

	kfree_skb(mhi_netdev->skbagg_head);

	free_netdev(ndev);

	dev_set_drvdata(&mhi_dev->dev, NULL);
}

static int mhi_net_probe(struct mhi_device *mhi_dev,
			 const struct mhi_device_id *id)
{
	const struct mhi_device_info *info = (struct mhi_device_info *)id->driver_data;
	struct net_device *ndev;
	int err;

	ndev = alloc_netdev(sizeof(struct mhi_net_dev), info->netname,
			    NET_NAME_PREDICTABLE, mhi_net_setup);
	if (!ndev)
		return -ENOMEM;

	SET_NETDEV_DEV(ndev, &mhi_dev->dev);

	err = mhi_net_newlink(mhi_dev, ndev);
	if (err) {
		free_netdev(ndev);
		return err;
	}

	return 0;
}

static void mhi_net_remove(struct mhi_device *mhi_dev)
{
	struct mhi_net_dev *mhi_netdev = dev_get_drvdata(&mhi_dev->dev);

	mhi_net_dellink(mhi_dev, mhi_netdev->ndev);
}

static const struct mhi_device_info mhi_hwip0 = {
	.netname = "mhi_hwip%d",
};

static const struct mhi_device_info mhi_swip0 = {
	.netname = "mhi_swip%d",
};

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 },
	{}
};
MODULE_DEVICE_TABLE(mhi, mhi_net_id_table);

static struct mhi_driver mhi_net_driver = {
	.probe = mhi_net_probe,
	.remove = mhi_net_remove,
	.dl_xfer_cb = mhi_net_dl_callback,
	.ul_xfer_cb = mhi_net_ul_callback,
	.id_table = mhi_net_id_table,
	.driver = {
		.name = "mhi_net",
	},
};

module_mhi_driver(mhi_net_driver);

MODULE_AUTHOR("Loic Poulain <loic.poulain@linaro.org>");
MODULE_DESCRIPTION("Network over MHI");
MODULE_LICENSE("GPL v2");
Commit	Line	Data
	1	// SPDX-License-Identifier: GPL-2.0-or-later
	2	/* MHI Network driver - Network over MHI bus
	3	*
	4	* Copyright (C) 2020 Linaro Ltd <loic.poulain@linaro.org>
	5	*/
	6
	7	#include <linux/if_arp.h>
	8	#include <linux/mhi.h>
	9	#include <linux/mod_devicetable.h>
	10	#include <linux/module.h>
	11	#include <linux/netdevice.h>
	12	#include <linux/skbuff.h>
	13	#include <linux/u64_stats_sync.h>
	14
	15	#define MHI_NET_MIN_MTU ETH_MIN_MTU
	16	#define MHI_NET_MAX_MTU 0xffff
	17	#define MHI_NET_DEFAULT_MTU 0x4000
	18
	19	struct mhi_net_stats {
	20	u64_stats_t rx_packets;
	21	u64_stats_t rx_bytes;
	22	u64_stats_t rx_errors;
	23	u64_stats_t tx_packets;
	24	u64_stats_t tx_bytes;
	25	u64_stats_t tx_errors;
	26	u64_stats_t tx_dropped;
	27	struct u64_stats_sync tx_syncp;
	28	struct u64_stats_sync rx_syncp;
	29	};
	30
	31	struct mhi_net_dev {
	32	struct mhi_device *mdev;
	33	struct net_device *ndev;
	34	struct sk_buff *skbagg_head;
	35	struct sk_buff *skbagg_tail;
	36	struct delayed_work rx_refill;
	37	struct mhi_net_stats stats;
	38	u32 rx_queue_sz;
	39	int msg_enable;
	40	unsigned int mru;
	41	};
	42
	43	struct mhi_device_info {
	44	const char *netname;
	45	};
	46
	47	static int mhi_ndo_open(struct net_device *ndev)
	48	{
	49	struct mhi_net_dev *mhi_netdev = netdev_priv(ndev);
	50
	51	/* Feed the rx buffer pool */
	52	schedule_delayed_work(&mhi_netdev->rx_refill, 0);
	53
	54	/* Carrier is established via out-of-band channel (e.g. qmi) */
	55	netif_carrier_on(ndev);
	56
	57	netif_start_queue(ndev);
	58
	59	return 0;
	60	}
	61
	62	static int mhi_ndo_stop(struct net_device *ndev)
	63	{
	64	struct mhi_net_dev *mhi_netdev = netdev_priv(ndev);
	65
	66	netif_stop_queue(ndev);
	67	netif_carrier_off(ndev);
	68	cancel_delayed_work_sync(&mhi_netdev->rx_refill);
	69
	70	return 0;
	71	}
	72
	73	static netdev_tx_t mhi_ndo_xmit(struct sk_buff skb, struct net_device ndev)
	74	{
	75	struct mhi_net_dev *mhi_netdev = netdev_priv(ndev);
	76	struct mhi_device *mdev = mhi_netdev->mdev;
	77	int err;
	78
	79	err = mhi_queue_skb(mdev, DMA_TO_DEVICE, skb, skb->len, MHI_EOT);
	80	if (unlikely(err)) {
	81	net_err_ratelimited("%s: Failed to queue TX buf (%d)\n",
	82	ndev->name, err);
	83	dev_kfree_skb_any(skb);
	84	goto exit_drop;
	85	}
	86
	87	if (mhi_queue_is_full(mdev, DMA_TO_DEVICE))
	88	netif_stop_queue(ndev);
	89
	90	return NETDEV_TX_OK;
	91
	92	exit_drop:
	93	u64_stats_update_begin(&mhi_netdev->stats.tx_syncp);
	94	u64_stats_inc(&mhi_netdev->stats.tx_dropped);
	95	u64_stats_update_end(&mhi_netdev->stats.tx_syncp);
	96
	97	return NETDEV_TX_OK;
	98	}
	99
	100	static void mhi_ndo_get_stats64(struct net_device *ndev,
	101	struct rtnl_link_stats64 *stats)
	102	{
	103	struct mhi_net_dev *mhi_netdev = netdev_priv(ndev);
	104	unsigned int start;
	105
	106	do {
	107	start = u64_stats_fetch_begin(&mhi_netdev->stats.rx_syncp);
	108	stats->rx_packets = u64_stats_read(&mhi_netdev->stats.rx_packets);
	109	stats->rx_bytes = u64_stats_read(&mhi_netdev->stats.rx_bytes);
	110	stats->rx_errors = u64_stats_read(&mhi_netdev->stats.rx_errors);
	111	} while (u64_stats_fetch_retry(&mhi_netdev->stats.rx_syncp, start));
	112
	113	do {
	114	start = u64_stats_fetch_begin(&mhi_netdev->stats.tx_syncp);
	115	stats->tx_packets = u64_stats_read(&mhi_netdev->stats.tx_packets);
	116	stats->tx_bytes = u64_stats_read(&mhi_netdev->stats.tx_bytes);
	117	stats->tx_errors = u64_stats_read(&mhi_netdev->stats.tx_errors);
	118	stats->tx_dropped = u64_stats_read(&mhi_netdev->stats.tx_dropped);
	119	} while (u64_stats_fetch_retry(&mhi_netdev->stats.tx_syncp, start));
	120	}
	121
	122	static const struct net_device_ops mhi_netdev_ops = {
	123	.ndo_open = mhi_ndo_open,
	124	.ndo_stop = mhi_ndo_stop,
	125	.ndo_start_xmit = mhi_ndo_xmit,
	126	.ndo_get_stats64 = mhi_ndo_get_stats64,
	127	};
	128
	129	static void mhi_net_setup(struct net_device *ndev)
	130	{
	131	ndev->header_ops = NULL; /* No header */
	132	ndev->type = ARPHRD_RAWIP;
	133	ndev->hard_header_len = 0;
	134	ndev->addr_len = 0;
	135	ndev->flags = IFF_POINTOPOINT \| IFF_NOARP;
	136	ndev->netdev_ops = &mhi_netdev_ops;
	137	ndev->mtu = MHI_NET_DEFAULT_MTU;
	138	ndev->min_mtu = MHI_NET_MIN_MTU;
	139	ndev->max_mtu = MHI_NET_MAX_MTU;
	140	ndev->tx_queue_len = 1000;
	141	}
	142
	143	static struct sk_buff mhi_net_skb_agg(struct mhi_net_dev mhi_netdev,
	144	struct sk_buff *skb)
	145	{
	146	struct sk_buff *head = mhi_netdev->skbagg_head;
	147	struct sk_buff *tail = mhi_netdev->skbagg_tail;
	148
	149	/* This is non-paged skb chaining using frag_list */
	150	if (!head) {
	151	mhi_netdev->skbagg_head = skb;
	152	return skb;
	153	}
	154
	155	if (!skb_shinfo(head)->frag_list)
	156	skb_shinfo(head)->frag_list = skb;
	157	else
	158	tail->next = skb;
	159
	160	head->len += skb->len;
	161	head->data_len += skb->len;
	162	head->truesize += skb->truesize;
	163
	164	mhi_netdev->skbagg_tail = skb;
	165
	166	return mhi_netdev->skbagg_head;
	167	}
	168
	169	static void mhi_net_dl_callback(struct mhi_device *mhi_dev,
	170	struct mhi_result *mhi_res)
	171	{
	172	struct mhi_net_dev *mhi_netdev = dev_get_drvdata(&mhi_dev->dev);
	173	struct sk_buff *skb = mhi_res->buf_addr;
	174	int free_desc_count;
	175
	176	free_desc_count = mhi_get_free_desc_count(mhi_dev, DMA_FROM_DEVICE);
	177
	178	if (unlikely(mhi_res->transaction_status)) {
	179	switch (mhi_res->transaction_status) {
	180	case -EOVERFLOW:
	181	/* Packet can not fit in one MHI buffer and has been
	182	* split over multiple MHI transfers, do re-aggregation.
	183	* That usually means the device side MTU is larger than
	184	* the host side MTU/MRU. Since this is not optimal,
	185	* print a warning (once).
	186	*/
	187	netdev_warn_once(mhi_netdev->ndev,
	188	"Fragmented packets received, fix MTU?\n");
	189	skb_put(skb, mhi_res->bytes_xferd);
	190	mhi_net_skb_agg(mhi_netdev, skb);
	191	break;
	192	case -ENOTCONN:
	193	/* MHI layer stopping/resetting the DL channel */
	194	dev_kfree_skb_any(skb);
	195	return;
	196	default:
	197	/* Unknown error, simply drop */
	198	dev_kfree_skb_any(skb);
	199	u64_stats_update_begin(&mhi_netdev->stats.rx_syncp);
	200	u64_stats_inc(&mhi_netdev->stats.rx_errors);
	201	u64_stats_update_end(&mhi_netdev->stats.rx_syncp);
	202	}
	203	} else {
	204	skb_put(skb, mhi_res->bytes_xferd);
	205
	206	if (mhi_netdev->skbagg_head) {
	207	/* Aggregate the final fragment */
	208	skb = mhi_net_skb_agg(mhi_netdev, skb);
	209	mhi_netdev->skbagg_head = NULL;
	210	}
	211
	212	switch (skb->data[0] & 0xf0) {
	213	case 0x40:
	214	skb->protocol = htons(ETH_P_IP);
	215	break;
	216	case 0x60:
	217	skb->protocol = htons(ETH_P_IPV6);
	218	break;
	219	default:
	220	skb->protocol = htons(ETH_P_MAP);
	221	break;
	222	}
	223
	224	u64_stats_update_begin(&mhi_netdev->stats.rx_syncp);
	225	u64_stats_inc(&mhi_netdev->stats.rx_packets);
	226	u64_stats_add(&mhi_netdev->stats.rx_bytes, skb->len);
	227	u64_stats_update_end(&mhi_netdev->stats.rx_syncp);
	228	__netif_rx(skb);
	229	}
	230
	231	/* Refill if RX buffers queue becomes low */
	232	if (free_desc_count >= mhi_netdev->rx_queue_sz / 2)
	233	schedule_delayed_work(&mhi_netdev->rx_refill, 0);
	234	}
	235
	236	static void mhi_net_ul_callback(struct mhi_device *mhi_dev,
	237	struct mhi_result *mhi_res)
	238	{
	239	struct mhi_net_dev *mhi_netdev = dev_get_drvdata(&mhi_dev->dev);
	240	struct net_device *ndev = mhi_netdev->ndev;
	241	struct mhi_device *mdev = mhi_netdev->mdev;
	242	struct sk_buff *skb = mhi_res->buf_addr;
	243
	244	/* Hardware has consumed the buffer, so free the skb (which is not
	245	* freed by the MHI stack) and perform accounting.
	246	*/
	247	dev_consume_skb_any(skb);
	248
	249	u64_stats_update_begin(&mhi_netdev->stats.tx_syncp);
	250	if (unlikely(mhi_res->transaction_status)) {
	251	/* MHI layer stopping/resetting the UL channel */
	252	if (mhi_res->transaction_status == -ENOTCONN) {
	253	u64_stats_update_end(&mhi_netdev->stats.tx_syncp);
	254	return;
	255	}
	256
	257	u64_stats_inc(&mhi_netdev->stats.tx_errors);
	258	} else {
	259	u64_stats_inc(&mhi_netdev->stats.tx_packets);
	260	u64_stats_add(&mhi_netdev->stats.tx_bytes, mhi_res->bytes_xferd);
	261	}
	262	u64_stats_update_end(&mhi_netdev->stats.tx_syncp);
	263
	264	if (netif_queue_stopped(ndev) && !mhi_queue_is_full(mdev, DMA_TO_DEVICE))
	265	netif_wake_queue(ndev);
	266	}
	267
	268	static void mhi_net_rx_refill_work(struct work_struct *work)
	269	{
	270	struct mhi_net_dev *mhi_netdev = container_of(work, struct mhi_net_dev,
	271	rx_refill.work);
	272	struct net_device *ndev = mhi_netdev->ndev;
	273	struct mhi_device *mdev = mhi_netdev->mdev;
	274	struct sk_buff *skb;
	275	unsigned int size;
	276	int err;
	277
	278	size = mhi_netdev->mru ? mhi_netdev->mru : READ_ONCE(ndev->mtu);
	279
	280	while (!mhi_queue_is_full(mdev, DMA_FROM_DEVICE)) {
	281	skb = netdev_alloc_skb(ndev, size);
	282	if (unlikely(!skb))
	283	break;
	284
	285	err = mhi_queue_skb(mdev, DMA_FROM_DEVICE, skb, size, MHI_EOT);
	286	if (unlikely(err)) {
	287	net_err_ratelimited("%s: Failed to queue RX buf (%d)\n",
	288	ndev->name, err);
	289	kfree_skb(skb);
	290	break;
	291	}
	292
	293	/* Do not hog the CPU if rx buffers are consumed faster than
	294	* queued (unlikely).
	295	*/
	296	cond_resched();
	297	}
	298
	299	/* If we're still starved of rx buffers, reschedule later */
	300	if (mhi_get_free_desc_count(mdev, DMA_FROM_DEVICE) == mhi_netdev->rx_queue_sz)
	301	schedule_delayed_work(&mhi_netdev->rx_refill, HZ / 2);
	302	}
	303
	304	static int mhi_net_newlink(struct mhi_device mhi_dev, struct net_device ndev)
	305	{
	306	struct mhi_net_dev *mhi_netdev;
	307	int err;
	308
	309	mhi_netdev = netdev_priv(ndev);
	310
	311	dev_set_drvdata(&mhi_dev->dev, mhi_netdev);
	312	mhi_netdev->ndev = ndev;
	313	mhi_netdev->mdev = mhi_dev;
	314	mhi_netdev->skbagg_head = NULL;
	315	mhi_netdev->mru = mhi_dev->mhi_cntrl->mru;
	316
	317	INIT_DELAYED_WORK(&mhi_netdev->rx_refill, mhi_net_rx_refill_work);
	318	u64_stats_init(&mhi_netdev->stats.rx_syncp);
	319	u64_stats_init(&mhi_netdev->stats.tx_syncp);
	320
	321	/* Start MHI channels */
	322	err = mhi_prepare_for_transfer(mhi_dev);
	323	if (err)
	324	return err;
	325
	326	/* Number of transfer descriptors determines size of the queue */
	327	mhi_netdev->rx_queue_sz = mhi_get_free_desc_count(mhi_dev, DMA_FROM_DEVICE);
	328
	329	err = register_netdev(ndev);
	330	if (err)
	331	return err;
	332
	333	return 0;
	334	}
	335
	336	static void mhi_net_dellink(struct mhi_device mhi_dev, struct net_device ndev)
	337	{
	338	struct mhi_net_dev *mhi_netdev = netdev_priv(ndev);
	339
	340	unregister_netdev(ndev);
	341
	342	mhi_unprepare_from_transfer(mhi_dev);
	343
	344	kfree_skb(mhi_netdev->skbagg_head);
	345
	346	free_netdev(ndev);
	347
	348	dev_set_drvdata(&mhi_dev->dev, NULL);
	349	}
	350
	351	static int mhi_net_probe(struct mhi_device *mhi_dev,
	352	const struct mhi_device_id *id)
	353	{
	354	const struct mhi_device_info info = (struct mhi_device_info )id->driver_data;
	355	struct net_device *ndev;
	356	int err;
	357
	358	ndev = alloc_netdev(sizeof(struct mhi_net_dev), info->netname,
	359	NET_NAME_PREDICTABLE, mhi_net_setup);
	360	if (!ndev)
	361	return -ENOMEM;
	362
	363	SET_NETDEV_DEV(ndev, &mhi_dev->dev);
	364
	365	err = mhi_net_newlink(mhi_dev, ndev);
	366	if (err) {
	367	free_netdev(ndev);
	368	return err;
	369	}
	370
	371	return 0;
	372	}
	373
	374	static void mhi_net_remove(struct mhi_device *mhi_dev)
	375	{
	376	struct mhi_net_dev *mhi_netdev = dev_get_drvdata(&mhi_dev->dev);
	377
	378	mhi_net_dellink(mhi_dev, mhi_netdev->ndev);
	379	}
	380
	381	static const struct mhi_device_info mhi_hwip0 = {
	382	.netname = "mhi_hwip%d",
	383	};
	384
	385	static const struct mhi_device_info mhi_swip0 = {
	386	.netname = "mhi_swip%d",
	387	};
	388
	389	static const struct mhi_device_id mhi_net_id_table[] = {
	390	/* Hardware accelerated data PATH (to modem IPA), protocol agnostic */
	391	{ .chan = "IP_HW0", .driver_data = (kernel_ulong_t)&mhi_hwip0 },
	392	/* Software data PATH (to modem CPU) */
	393	{ .chan = "IP_SW0", .driver_data = (kernel_ulong_t)&mhi_swip0 },
	394	{}
	395	};
	396	MODULE_DEVICE_TABLE(mhi, mhi_net_id_table);
	397
	398	static struct mhi_driver mhi_net_driver = {
	399	.probe = mhi_net_probe,
	400	.remove = mhi_net_remove,
	401	.dl_xfer_cb = mhi_net_dl_callback,
	402	.ul_xfer_cb = mhi_net_ul_callback,
	403	.id_table = mhi_net_id_table,
	404	.driver = {
	405	.name = "mhi_net",
	406	},
	407	};
	408
	409	module_mhi_driver(mhi_net_driver);
	410
	411	MODULE_AUTHOR("Loic Poulain <loic.poulain@linaro.org>");
	412	MODULE_DESCRIPTION("Network over MHI");
	413	MODULE_LICENSE("GPL v2");