drivers/net/ethernet/qualcomm/qca_uart.c - linux - Git at Google

 /*
  *   Copyright (c) 2011, 2012, Qualcomm Atheros Communications Inc.
  *   Copyright (c) 2017, I2SE GmbH
  *
  *   Permission to use, copy, modify, and/or distribute this software
  *   for any purpose with or without fee is hereby granted, provided
  *   that the above copyright notice and this permission notice appear
  *   in all copies.
  *
  *   THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL
  *   WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED
  *   WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL
  *   THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR
  *   CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
  *   LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
  *   NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
  *   CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */

 /*   This module implements the Qualcomm Atheros UART protocol for
  *   kernel-based UART device; it is essentially an Ethernet-to-UART
  *   serial converter;
  */

 #include <linux/device.h>
 #include <linux/errno.h>
 #include <linux/etherdevice.h>
 #include <linux/if_arp.h>
 #include <linux/if_ether.h>
 #include <linux/jiffies.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/netdevice.h>
 #include <linux/of.h>
 #include <linux/of_device.h>
 #include <linux/of_net.h>
 #include <linux/sched.h>
 #include <linux/serdev.h>
 #include <linux/skbuff.h>
 #include <linux/types.h>

 #include "qca_7k_common.h"

 #define QCAUART_DRV_VERSION "0.1.0"
 #define QCAUART_DRV_NAME "qcauart"
 #define QCAUART_TX_TIMEOUT (1 * HZ)

 struct qcauart {
 	struct net_device *net_dev;
 	spinlock_t lock;			/* transmit lock */
 	struct work_struct tx_work;		/* Flushes transmit buffer   */

 	struct serdev_device *serdev;
 	struct qcafrm_handle frm_handle;
 	struct sk_buff *rx_skb;

 	unsigned char *tx_head;			/* pointer to next XMIT byte */
 	int tx_left;				/* bytes left in XMIT queue  */
 	unsigned char *tx_buffer;
 };

 static int
 qca_tty_receive(struct serdev_device *serdev, const unsigned char *data,
 		size_t count)
 {
 	struct qcauart *qca = serdev_device_get_drvdata(serdev);
 	struct net_device *netdev = qca->net_dev;
 	struct net_device_stats *n_stats = &netdev->stats;
 	size_t i;

 	if (!qca->rx_skb) {
 		qca->rx_skb = netdev_alloc_skb_ip_align(netdev,
 							netdev->mtu +
 							VLAN_ETH_HLEN);
 		if (!qca->rx_skb) {
 			n_stats->rx_errors++;
 			n_stats->rx_dropped++;
 			return 0;
 		}
 	}

 	for (i = 0; i < count; i++) {
 		s32 retcode;

 		retcode = qcafrm_fsm_decode(&qca->frm_handle,
 					    qca->rx_skb->data,
 					    skb_tailroom(qca->rx_skb),
 					    data[i]);

 		switch (retcode) {
 		case QCAFRM_GATHER:
 		case QCAFRM_NOHEAD:
 			break;
 		case QCAFRM_NOTAIL:
 			netdev_dbg(netdev, "recv: no RX tail\n");
 			n_stats->rx_errors++;
 			n_stats->rx_dropped++;
 			break;
 		case QCAFRM_INVLEN:
 			netdev_dbg(netdev, "recv: invalid RX length\n");
 			n_stats->rx_errors++;
 			n_stats->rx_dropped++;
 			break;
 		default:
 			n_stats->rx_packets++;
 			n_stats->rx_bytes += retcode;
 			skb_put(qca->rx_skb, retcode);
 			qca->rx_skb->protocol = eth_type_trans(
 						qca->rx_skb, qca->rx_skb->dev);
 			qca->rx_skb->ip_summed = CHECKSUM_UNNECESSARY;
 			netif_rx_ni(qca->rx_skb);
 			qca->rx_skb = netdev_alloc_skb_ip_align(netdev,
 								netdev->mtu +
 								VLAN_ETH_HLEN);
 			if (!qca->rx_skb) {
 				netdev_dbg(netdev, "recv: out of RX resources\n");
 				n_stats->rx_errors++;
 				return i;
 			}
 		}
 	}

 	return i;
 }

 /* Write out any remaining transmit buffer. Scheduled when tty is writable */
 static void qcauart_transmit(struct work_struct *work)
 {
 	struct qcauart *qca = container_of(work, struct qcauart, tx_work);
 	struct net_device_stats *n_stats = &qca->net_dev->stats;
 	int written;

 	spin_lock_bh(&qca->lock);

 	/* First make sure we're connected. */
 	if (!netif_running(qca->net_dev)) {
 		spin_unlock_bh(&qca->lock);
 		return;
 	}

 	if (qca->tx_left <= 0)  {
 		/* Now serial buffer is almost free & we can start
 		 * transmission of another packet
 		 */
 		n_stats->tx_packets++;
 		spin_unlock_bh(&qca->lock);
 		netif_wake_queue(qca->net_dev);
 		return;
 	}

 	written = serdev_device_write_buf(qca->serdev, qca->tx_head,
 					  qca->tx_left);
 	if (written > 0) {
 		qca->tx_left -= written;
 		qca->tx_head += written;
 	}
 	spin_unlock_bh(&qca->lock);
 }

 /* Called by the driver when there's room for more data.
  * Schedule the transmit.
  */
 static void qca_tty_wakeup(struct serdev_device *serdev)
 {
 	struct qcauart *qca = serdev_device_get_drvdata(serdev);

 	schedule_work(&qca->tx_work);
 }

 static struct serdev_device_ops qca_serdev_ops = {
 	.receive_buf = qca_tty_receive,
 	.write_wakeup = qca_tty_wakeup,
 };

 static int qcauart_netdev_open(struct net_device *dev)
 {
 	struct qcauart *qca = netdev_priv(dev);

 	netif_start_queue(qca->net_dev);

 	return 0;
 }

 static int qcauart_netdev_close(struct net_device *dev)
 {
 	struct qcauart *qca = netdev_priv(dev);

 	netif_stop_queue(dev);
 	flush_work(&qca->tx_work);

 	spin_lock_bh(&qca->lock);
 	qca->tx_left = 0;
 	spin_unlock_bh(&qca->lock);

 	return 0;
 }

 static netdev_tx_t
 qcauart_netdev_xmit(struct sk_buff *skb, struct net_device *dev)
 {
 	struct net_device_stats *n_stats = &dev->stats;
 	struct qcauart *qca = netdev_priv(dev);
 	u8 pad_len = 0;
 	int written;
 	u8 *pos;

 	spin_lock(&qca->lock);

 	WARN_ON(qca->tx_left);

 	if (!netif_running(dev))  {
 		spin_unlock(&qca->lock);
 		netdev_warn(qca->net_dev, "xmit: iface is down\n");
 		goto out;
 	}

 	pos = qca->tx_buffer;

 	if (skb->len < QCAFRM_MIN_LEN)
 		pad_len = QCAFRM_MIN_LEN - skb->len;

 	pos += qcafrm_create_header(pos, skb->len + pad_len);

 	memcpy(pos, skb->data, skb->len);
 	pos += skb->len;

 	if (pad_len) {
 		memset(pos, 0, pad_len);
 		pos += pad_len;
 	}

 	pos += qcafrm_create_footer(pos);

 	netif_stop_queue(qca->net_dev);

 	written = serdev_device_write_buf(qca->serdev, qca->tx_buffer,
 					  pos - qca->tx_buffer);
 	if (written > 0) {
 		qca->tx_left = (pos - qca->tx_buffer) - written;
 		qca->tx_head = qca->tx_buffer + written;
 		n_stats->tx_bytes += written;
 	}
 	spin_unlock(&qca->lock);

 	netif_trans_update(dev);
 out:
 	dev_kfree_skb_any(skb);
 	return NETDEV_TX_OK;
 }

 static void qcauart_netdev_tx_timeout(struct net_device *dev)
 {
 	struct qcauart *qca = netdev_priv(dev);

 	netdev_info(qca->net_dev, "Transmit timeout at %ld, latency %ld\n",
 		    jiffies, dev_trans_start(dev));
 	dev->stats.tx_errors++;
 	dev->stats.tx_dropped++;
 }

 static int qcauart_netdev_init(struct net_device *dev)
 {
 	struct qcauart *qca = netdev_priv(dev);
 	size_t len;

 	/* Finish setting up the device info. */
 	dev->mtu = QCAFRM_MAX_MTU;
 	dev->type = ARPHRD_ETHER;

 	len = QCAFRM_HEADER_LEN + QCAFRM_MAX_LEN + QCAFRM_FOOTER_LEN;
 	qca->tx_buffer = devm_kmalloc(&qca->serdev->dev, len, GFP_KERNEL);
 	if (!qca->tx_buffer)
 		return -ENOMEM;

 	qca->rx_skb = netdev_alloc_skb_ip_align(qca->net_dev,
 						qca->net_dev->mtu +
 						VLAN_ETH_HLEN);
 	if (!qca->rx_skb)
 		return -ENOBUFS;

 	return 0;
 }

 static void qcauart_netdev_uninit(struct net_device *dev)
 {
 	struct qcauart *qca = netdev_priv(dev);

 	if (qca->rx_skb)
 		dev_kfree_skb(qca->rx_skb);
 }

 static const struct net_device_ops qcauart_netdev_ops = {
 	.ndo_init = qcauart_netdev_init,
 	.ndo_uninit = qcauart_netdev_uninit,
 	.ndo_open = qcauart_netdev_open,
 	.ndo_stop = qcauart_netdev_close,
 	.ndo_start_xmit = qcauart_netdev_xmit,
 	.ndo_set_mac_address = eth_mac_addr,
 	.ndo_tx_timeout = qcauart_netdev_tx_timeout,
 	.ndo_validate_addr = eth_validate_addr,
 };

 static void qcauart_netdev_setup(struct net_device *dev)
 {
 	dev->netdev_ops = &qcauart_netdev_ops;
 	dev->watchdog_timeo = QCAUART_TX_TIMEOUT;
 	dev->priv_flags &= ~IFF_TX_SKB_SHARING;
 	dev->tx_queue_len = 100;

 	/* MTU range: 46 - 1500 */
 	dev->min_mtu = QCAFRM_MIN_MTU;
 	dev->max_mtu = QCAFRM_MAX_MTU;
 }

 static const struct of_device_id qca_uart_of_match[] = {
 	{
 	 .compatible = "qca,qca7000",
 	},
 	{}
 };
 MODULE_DEVICE_TABLE(of, qca_uart_of_match);

 static int qca_uart_probe(struct serdev_device *serdev)
 {
 	struct net_device *qcauart_dev = alloc_etherdev(sizeof(struct qcauart));
 	struct qcauart *qca;
 	const char *mac;
 	u32 speed = 115200;
 	int ret;

 	if (!qcauart_dev)
 		return -ENOMEM;

 	qcauart_netdev_setup(qcauart_dev);
 	SET_NETDEV_DEV(qcauart_dev, &serdev->dev);

 	qca = netdev_priv(qcauart_dev);
 	if (!qca) {
 		pr_err("qca_uart: Fail to retrieve private structure\n");
 		ret = -ENOMEM;
 		goto free;
 	}
 	qca->net_dev = qcauart_dev;
 	qca->serdev = serdev;
 	qcafrm_fsm_init_uart(&qca->frm_handle);

 	spin_lock_init(&qca->lock);
 	INIT_WORK(&qca->tx_work, qcauart_transmit);

 	of_property_read_u32(serdev->dev.of_node, "current-speed", &speed);

 	mac = of_get_mac_address(serdev->dev.of_node);

 	if (mac)
 		ether_addr_copy(qca->net_dev->dev_addr, mac);

 	if (!is_valid_ether_addr(qca->net_dev->dev_addr)) {
 		eth_hw_addr_random(qca->net_dev);
 		dev_info(&serdev->dev, "Using random MAC address: %pM\n",
 			 qca->net_dev->dev_addr);
 	}

 	netif_carrier_on(qca->net_dev);
 	serdev_device_set_drvdata(serdev, qca);
 	serdev_device_set_client_ops(serdev, &qca_serdev_ops);

 	ret = serdev_device_open(serdev);
 	if (ret) {
 		dev_err(&serdev->dev, "Unable to open device %s\n",
 			qcauart_dev->name);
 		goto free;
 	}

 	speed = serdev_device_set_baudrate(serdev, speed);
 	dev_info(&serdev->dev, "Using baudrate: %u\n", speed);

 	serdev_device_set_flow_control(serdev, false);

 	ret = register_netdev(qcauart_dev);
 	if (ret) {
 		dev_err(&serdev->dev, "Unable to register net device %s\n",
 			qcauart_dev->name);
 		serdev_device_close(serdev);
 		cancel_work_sync(&qca->tx_work);
 		goto free;
 	}

 	return 0;

 free:
 	free_netdev(qcauart_dev);
 	return ret;
 }

 static void qca_uart_remove(struct serdev_device *serdev)
 {
 	struct qcauart *qca = serdev_device_get_drvdata(serdev);

 	unregister_netdev(qca->net_dev);

 	/* Flush any pending characters in the driver. */
 	serdev_device_close(serdev);
 	cancel_work_sync(&qca->tx_work);

 	free_netdev(qca->net_dev);
 }

 static struct serdev_device_driver qca_uart_driver = {
 	.probe = qca_uart_probe,
 	.remove = qca_uart_remove,
 	.driver = {
 		.name = QCAUART_DRV_NAME,
 		.of_match_table = of_match_ptr(qca_uart_of_match),
 	},
 };

 module_serdev_device_driver(qca_uart_driver);

 MODULE_DESCRIPTION("Qualcomm Atheros QCA7000 UART Driver");
 MODULE_AUTHOR("Qualcomm Atheros Communications");
 MODULE_AUTHOR("Stefan Wahren <stefan.wahren@i2se.com>");
 MODULE_LICENSE("Dual BSD/GPL");
 MODULE_VERSION(QCAUART_DRV_VERSION);
	/*
	* Copyright (c) 2011, 2012, Qualcomm Atheros Communications Inc.
	* Copyright (c) 2017, I2SE GmbH
	*
	* Permission to use, copy, modify, and/or distribute this software
	* for any purpose with or without fee is hereby granted, provided
	* that the above copyright notice and this permission notice appear
	* in all copies.
	*
	* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL
	* WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED
	* WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL
	* THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR
	* CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
	* LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
	* NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
	* CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
	*/

	/* This module implements the Qualcomm Atheros UART protocol for
	* kernel-based UART device; it is essentially an Ethernet-to-UART
	* serial converter;
	*/

	#include <linux/device.h>
	#include <linux/errno.h>
	#include <linux/etherdevice.h>
	#include <linux/if_arp.h>
	#include <linux/if_ether.h>
	#include <linux/jiffies.h>
	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/netdevice.h>
	#include <linux/of.h>
	#include <linux/of_device.h>
	#include <linux/of_net.h>
	#include <linux/sched.h>
	#include <linux/serdev.h>
	#include <linux/skbuff.h>
	#include <linux/types.h>

	#include "qca_7k_common.h"

	#define QCAUART_DRV_VERSION "0.1.0"
	#define QCAUART_DRV_NAME "qcauart"
	#define QCAUART_TX_TIMEOUT (1 * HZ)

	struct qcauart {
	struct net_device *net_dev;
	spinlock_t lock; /* transmit lock */
	struct work_struct tx_work; /* Flushes transmit buffer */

	struct serdev_device *serdev;
	struct qcafrm_handle frm_handle;
	struct sk_buff *rx_skb;

	unsigned char tx_head; / pointer to next XMIT byte */
	int tx_left; /* bytes left in XMIT queue */
	unsigned char *tx_buffer;
	};

	static int
	qca_tty_receive(struct serdev_device serdev, const unsigned char data,
	size_t count)
	{
	struct qcauart *qca = serdev_device_get_drvdata(serdev);
	struct net_device *netdev = qca->net_dev;
	struct net_device_stats *n_stats = &netdev->stats;
	size_t i;

	if (!qca->rx_skb) {
	qca->rx_skb = netdev_alloc_skb_ip_align(netdev,
	netdev->mtu +
	VLAN_ETH_HLEN);
	if (!qca->rx_skb) {
	n_stats->rx_errors++;
	n_stats->rx_dropped++;
	return 0;
	}
	}

	for (i = 0; i < count; i++) {
	s32 retcode;

	retcode = qcafrm_fsm_decode(&qca->frm_handle,
	qca->rx_skb->data,
	skb_tailroom(qca->rx_skb),
	data[i]);

	switch (retcode) {
	case QCAFRM_GATHER:
	case QCAFRM_NOHEAD:
	break;
	case QCAFRM_NOTAIL:
	netdev_dbg(netdev, "recv: no RX tail\n");
	n_stats->rx_errors++;
	n_stats->rx_dropped++;
	break;
	case QCAFRM_INVLEN:
	netdev_dbg(netdev, "recv: invalid RX length\n");
	n_stats->rx_errors++;
	n_stats->rx_dropped++;
	break;
	default:
	n_stats->rx_packets++;
	n_stats->rx_bytes += retcode;
	skb_put(qca->rx_skb, retcode);
	qca->rx_skb->protocol = eth_type_trans(
	qca->rx_skb, qca->rx_skb->dev);
	qca->rx_skb->ip_summed = CHECKSUM_UNNECESSARY;
	netif_rx_ni(qca->rx_skb);
	qca->rx_skb = netdev_alloc_skb_ip_align(netdev,
	netdev->mtu +
	VLAN_ETH_HLEN);
	if (!qca->rx_skb) {
	netdev_dbg(netdev, "recv: out of RX resources\n");
	n_stats->rx_errors++;
	return i;
	}
	}
	}

	return i;
	}

	/* Write out any remaining transmit buffer. Scheduled when tty is writable */
	static void qcauart_transmit(struct work_struct *work)
	{
	struct qcauart *qca = container_of(work, struct qcauart, tx_work);
	struct net_device_stats *n_stats = &qca->net_dev->stats;
	int written;

	spin_lock_bh(&qca->lock);

	/* First make sure we're connected. */
	if (!netif_running(qca->net_dev)) {
	spin_unlock_bh(&qca->lock);
	return;
	}

	if (qca->tx_left <= 0) {
	/* Now serial buffer is almost free & we can start
	* transmission of another packet
	*/
	n_stats->tx_packets++;
	spin_unlock_bh(&qca->lock);
	netif_wake_queue(qca->net_dev);
	return;
	}

	written = serdev_device_write_buf(qca->serdev, qca->tx_head,
	qca->tx_left);
	if (written > 0) {
	qca->tx_left -= written;
	qca->tx_head += written;
	}
	spin_unlock_bh(&qca->lock);
	}

	/* Called by the driver when there's room for more data.
	* Schedule the transmit.
	*/
	static void qca_tty_wakeup(struct serdev_device *serdev)
	{
	struct qcauart *qca = serdev_device_get_drvdata(serdev);

	schedule_work(&qca->tx_work);
	}

	static struct serdev_device_ops qca_serdev_ops = {
	.receive_buf = qca_tty_receive,
	.write_wakeup = qca_tty_wakeup,
	};

	static int qcauart_netdev_open(struct net_device *dev)
	{
	struct qcauart *qca = netdev_priv(dev);

	netif_start_queue(qca->net_dev);

	return 0;
	}

	static int qcauart_netdev_close(struct net_device *dev)
	{
	struct qcauart *qca = netdev_priv(dev);

	netif_stop_queue(dev);
	flush_work(&qca->tx_work);

	spin_lock_bh(&qca->lock);
	qca->tx_left = 0;
	spin_unlock_bh(&qca->lock);

	return 0;
	}

	static netdev_tx_t
	qcauart_netdev_xmit(struct sk_buff skb, struct net_device dev)
	{
	struct net_device_stats *n_stats = &dev->stats;
	struct qcauart *qca = netdev_priv(dev);
	u8 pad_len = 0;
	int written;
	u8 *pos;

	spin_lock(&qca->lock);

	WARN_ON(qca->tx_left);

	if (!netif_running(dev)) {
	spin_unlock(&qca->lock);
	netdev_warn(qca->net_dev, "xmit: iface is down\n");
	goto out;
	}

	pos = qca->tx_buffer;

	if (skb->len < QCAFRM_MIN_LEN)
	pad_len = QCAFRM_MIN_LEN - skb->len;

	pos += qcafrm_create_header(pos, skb->len + pad_len);

	memcpy(pos, skb->data, skb->len);
	pos += skb->len;

	if (pad_len) {
	memset(pos, 0, pad_len);
	pos += pad_len;
	}

	pos += qcafrm_create_footer(pos);

	netif_stop_queue(qca->net_dev);

	written = serdev_device_write_buf(qca->serdev, qca->tx_buffer,
	pos - qca->tx_buffer);
	if (written > 0) {
	qca->tx_left = (pos - qca->tx_buffer) - written;
	qca->tx_head = qca->tx_buffer + written;
	n_stats->tx_bytes += written;
	}
	spin_unlock(&qca->lock);

	netif_trans_update(dev);
	out:
	dev_kfree_skb_any(skb);
	return NETDEV_TX_OK;
	}

	static void qcauart_netdev_tx_timeout(struct net_device *dev)
	{
	struct qcauart *qca = netdev_priv(dev);

	netdev_info(qca->net_dev, "Transmit timeout at %ld, latency %ld\n",
	jiffies, dev_trans_start(dev));
	dev->stats.tx_errors++;
	dev->stats.tx_dropped++;
	}

	static int qcauart_netdev_init(struct net_device *dev)
	{
	struct qcauart *qca = netdev_priv(dev);
	size_t len;

	/* Finish setting up the device info. */
	dev->mtu = QCAFRM_MAX_MTU;
	dev->type = ARPHRD_ETHER;

	len = QCAFRM_HEADER_LEN + QCAFRM_MAX_LEN + QCAFRM_FOOTER_LEN;
	qca->tx_buffer = devm_kmalloc(&qca->serdev->dev, len, GFP_KERNEL);
	if (!qca->tx_buffer)
	return -ENOMEM;

	qca->rx_skb = netdev_alloc_skb_ip_align(qca->net_dev,
	qca->net_dev->mtu +
	VLAN_ETH_HLEN);
	if (!qca->rx_skb)
	return -ENOBUFS;

	return 0;
	}

	static void qcauart_netdev_uninit(struct net_device *dev)
	{
	struct qcauart *qca = netdev_priv(dev);

	if (qca->rx_skb)
	dev_kfree_skb(qca->rx_skb);
	}

	static const struct net_device_ops qcauart_netdev_ops = {
	.ndo_init = qcauart_netdev_init,
	.ndo_uninit = qcauart_netdev_uninit,
	.ndo_open = qcauart_netdev_open,
	.ndo_stop = qcauart_netdev_close,
	.ndo_start_xmit = qcauart_netdev_xmit,
	.ndo_set_mac_address = eth_mac_addr,
	.ndo_tx_timeout = qcauart_netdev_tx_timeout,
	.ndo_validate_addr = eth_validate_addr,
	};

	static void qcauart_netdev_setup(struct net_device *dev)
	{
	dev->netdev_ops = &qcauart_netdev_ops;
	dev->watchdog_timeo = QCAUART_TX_TIMEOUT;
	dev->priv_flags &= ~IFF_TX_SKB_SHARING;
	dev->tx_queue_len = 100;

	/* MTU range: 46 - 1500 */
	dev->min_mtu = QCAFRM_MIN_MTU;
	dev->max_mtu = QCAFRM_MAX_MTU;
	}

	static const struct of_device_id qca_uart_of_match[] = {
	{
	.compatible = "qca,qca7000",
	},
	{}
	};
	MODULE_DEVICE_TABLE(of, qca_uart_of_match);

	static int qca_uart_probe(struct serdev_device *serdev)
	{
	struct net_device *qcauart_dev = alloc_etherdev(sizeof(struct qcauart));
	struct qcauart *qca;
	const char *mac;
	u32 speed = 115200;
	int ret;

	if (!qcauart_dev)
	return -ENOMEM;

	qcauart_netdev_setup(qcauart_dev);
	SET_NETDEV_DEV(qcauart_dev, &serdev->dev);

	qca = netdev_priv(qcauart_dev);
	if (!qca) {
	pr_err("qca_uart: Fail to retrieve private structure\n");
	ret = -ENOMEM;
	goto free;
	}
	qca->net_dev = qcauart_dev;
	qca->serdev = serdev;
	qcafrm_fsm_init_uart(&qca->frm_handle);

	spin_lock_init(&qca->lock);
	INIT_WORK(&qca->tx_work, qcauart_transmit);

	of_property_read_u32(serdev->dev.of_node, "current-speed", &speed);

	mac = of_get_mac_address(serdev->dev.of_node);

	if (mac)
	ether_addr_copy(qca->net_dev->dev_addr, mac);

	if (!is_valid_ether_addr(qca->net_dev->dev_addr)) {
	eth_hw_addr_random(qca->net_dev);
	dev_info(&serdev->dev, "Using random MAC address: %pM\n",
	qca->net_dev->dev_addr);
	}

	netif_carrier_on(qca->net_dev);
	serdev_device_set_drvdata(serdev, qca);
	serdev_device_set_client_ops(serdev, &qca_serdev_ops);

	ret = serdev_device_open(serdev);
	if (ret) {
	dev_err(&serdev->dev, "Unable to open device %s\n",
	qcauart_dev->name);
	goto free;
	}

	speed = serdev_device_set_baudrate(serdev, speed);
	dev_info(&serdev->dev, "Using baudrate: %u\n", speed);

	serdev_device_set_flow_control(serdev, false);

	ret = register_netdev(qcauart_dev);
	if (ret) {
	dev_err(&serdev->dev, "Unable to register net device %s\n",
	qcauart_dev->name);
	serdev_device_close(serdev);
	cancel_work_sync(&qca->tx_work);
	goto free;
	}

	return 0;

	free:
	free_netdev(qcauart_dev);
	return ret;
	}

	static void qca_uart_remove(struct serdev_device *serdev)
	{
	struct qcauart *qca = serdev_device_get_drvdata(serdev);

	unregister_netdev(qca->net_dev);

	/* Flush any pending characters in the driver. */
	serdev_device_close(serdev);
	cancel_work_sync(&qca->tx_work);

	free_netdev(qca->net_dev);
	}

	static struct serdev_device_driver qca_uart_driver = {
	.probe = qca_uart_probe,
	.remove = qca_uart_remove,
	.driver = {
	.name = QCAUART_DRV_NAME,
	.of_match_table = of_match_ptr(qca_uart_of_match),
	},
	};

	module_serdev_device_driver(qca_uart_driver);

	MODULE_DESCRIPTION("Qualcomm Atheros QCA7000 UART Driver");
	MODULE_AUTHOR("Qualcomm Atheros Communications");
	MODULE_AUTHOR("Stefan Wahren <stefan.wahren@i2se.com>");
	MODULE_LICENSE("Dual BSD/GPL");
	MODULE_VERSION(QCAUART_DRV_VERSION);