text: /*
   *   Copyright (c) 2011, 2012, Qualcomm Atheros Communications Inc.
   *   Copyright (c) 2014, 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 SPI protocol for
   *   kernel-based SPI device; it is essentially an Ethernet-to-SPI
   *   serial converter;
   */
  
  #include <linux/errno.h>
  #include <linux/etherdevice.h>
  #include <linux/if_arp.h>
  #include <linux/if_ether.h>
  #include <linux/init.h>
  #include <linux/interrupt.h>
  #include <linux/jiffies.h>
  #include <linux/kernel.h>
  #include <linux/kthread.h>
  #include <linux/module.h>
  #include <linux/moduleparam.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/skbuff.h>
  #include <linux/spi/spi.h>
  #include <linux/types.h>
  
  #include "qca_7k.h"
  #include "qca_7k_common.h"
  #include "qca_debug.h"
  #include "qca_spi.h"
  
  #define MAX_DMA_BURST_LEN 5000
  
  /*   Modules parameters     */
  #define QCASPI_CLK_SPEED_MIN 1000000
  #define QCASPI_CLK_SPEED_MAX 16000000
  #define QCASPI_CLK_SPEED     8000000
  static int qcaspi_clkspeed;
  module_param(qcaspi_clkspeed, int, 0);
  MODULE_PARM_DESC(qcaspi_clkspeed, "SPI bus clock speed (Hz). Use 1000000-16000000.");
  
  #define QCASPI_BURST_LEN_MIN 1
  #define QCASPI_BURST_LEN_MAX MAX_DMA_BURST_LEN
  static int qcaspi_burst_len = MAX_DMA_BURST_LEN;
  module_param(qcaspi_burst_len, int, 0);
  MODULE_PARM_DESC(qcaspi_burst_len, "Number of data bytes per burst. Use 1-5000.");
  
  #define QCASPI_PLUGGABLE_MIN 0
  #define QCASPI_PLUGGABLE_MAX 1
  static int qcaspi_pluggable = QCASPI_PLUGGABLE_MIN;
  module_param(qcaspi_pluggable, int, 0);
  MODULE_PARM_DESC(qcaspi_pluggable, "Pluggable SPI connection (yes/no).");
  
  #define QCASPI_TX_TIMEOUT (1 * HZ)
  #define QCASPI_QCA7K_REBOOT_TIME_MS 1000
  
  static void
  start_spi_intr_handling(struct qcaspi *qca, u16 *intr_cause)
  {
  	*intr_cause = 0;
  
  	qcaspi_write_register(qca, SPI_REG_INTR_ENABLE, 0);
  	qcaspi_read_register(qca, SPI_REG_INTR_CAUSE, intr_cause);
  	netdev_dbg(qca->net_dev, "interrupts: 0x%04x\n", *intr_cause);
  }
  
  static void
  end_spi_intr_handling(struct qcaspi *qca, u16 intr_cause)
  {
  	u16 intr_enable = (SPI_INT_CPU_ON |
  			   SPI_INT_PKT_AVLBL |
  			   SPI_INT_RDBUF_ERR |
  			   SPI_INT_WRBUF_ERR);
  
  	qcaspi_write_register(qca, SPI_REG_INTR_CAUSE, intr_cause);
  	qcaspi_write_register(qca, SPI_REG_INTR_ENABLE, intr_enable);
  	netdev_dbg(qca->net_dev, "acking int: 0x%04x\n", intr_cause);
  }
  
  static u32
  qcaspi_write_burst(struct qcaspi *qca, u8 *src, u32 len)
  {
  	__be16 cmd;
  	struct spi_message msg;
  	struct spi_transfer transfer[2];
  	int ret;
  
  	memset(&transfer, 0, sizeof(transfer));
  	spi_message_init(&msg);
  
  	cmd = cpu_to_be16(QCA7K_SPI_WRITE | QCA7K_SPI_EXTERNAL);
  	transfer[0].tx_buf = &cmd;
  	transfer[0].len = QCASPI_CMD_LEN;
  	transfer[1].tx_buf = src;
  	transfer[1].len = len;
  
  	spi_message_add_tail(&transfer[0], &msg);
  	spi_message_add_tail(&transfer[1], &msg);
  	ret = spi_sync(qca->spi_dev, &msg);
  
  	if (ret || (msg.actual_length != QCASPI_CMD_LEN + len)) {
  		qcaspi_spi_error(qca);
  		return 0;
  	}
  
  	return len;
  }
  
  static u32
  qcaspi_write_legacy(struct qcaspi *qca, u8 *src, u32 len)
  {
  	struct spi_message msg;
  	struct spi_transfer transfer;
  	int ret;
  
  	memset(&transfer, 0, sizeof(transfer));
  	spi_message_init(&msg);
  
  	transfer.tx_buf = src;
  	transfer.len = len;
  
  	spi_message_add_tail(&transfer, &msg);
  	ret = spi_sync(qca->spi_dev, &msg);
  
  	if (ret || (msg.actual_length != len)) {
  		qcaspi_spi_error(qca);
  		return 0;
  	}
  
  	return len;
  }
  
  static u32
  qcaspi_read_burst(struct qcaspi *qca, u8 *dst, u32 len)
  {
  	struct spi_message msg;
  	__be16 cmd;
  	struct spi_transfer transfer[2];
  	int ret;
  
  	memset(&transfer, 0, sizeof(transfer));
  	spi_message_init(&msg);
  
  	cmd = cpu_to_be16(QCA7K_SPI_READ | QCA7K_SPI_EXTERNAL);
  	transfer[0].tx_buf = &cmd;
  	transfer[0].len = QCASPI_CMD_LEN;
  	transfer[1].rx_buf = dst;
  	transfer[1].len = len;
  
  	spi_message_add_tail(&transfer[0], &msg);
  	spi_message_add_tail(&transfer[1], &msg);
  	ret = spi_sync(qca->spi_dev, &msg);
  
  	if (ret || (msg.actual_length != QCASPI_CMD_LEN + len)) {
  		qcaspi_spi_error(qca);
  		return 0;
  	}
  
  	return len;
  }
  
  static u32
  qcaspi_read_legacy(struct qcaspi *qca, u8 *dst, u32 len)
  {
  	struct spi_message msg;
  	struct spi_transfer transfer;
  	int ret;
  
  	memset(&transfer, 0, sizeof(transfer));
  	spi_message_init(&msg);
  
  	transfer.rx_buf = dst;
  	transfer.len = len;
  
  	spi_message_add_tail(&transfer, &msg);
  	ret = spi_sync(qca->spi_dev, &msg);
  
  	if (ret || (msg.actual_length != len)) {
  		qcaspi_spi_error(qca);
  		return 0;
  	}
  
  	return len;
  }
  
  static int
  qcaspi_tx_cmd(struct qcaspi *qca, u16 cmd)
  {
  	__be16 tx_data;
  	struct spi_message msg;
  	struct spi_transfer transfer;
  	int ret;
  
  	memset(&transfer, 0, sizeof(transfer));
  
  	spi_message_init(&msg);
  
  	tx_data = cpu_to_be16(cmd);
  	transfer.len = sizeof(cmd);
  	transfer.tx_buf = &tx_data;
  	spi_message_add_tail(&transfer, &msg);
  
  	ret = spi_sync(qca->spi_dev, &msg);
  
  	if (!ret)
  		ret = msg.status;
  
  	if (ret)
  		qcaspi_spi_error(qca);
  
  	return ret;
  }
  
  static int
  qcaspi_tx_frame(struct qcaspi *qca, struct sk_buff *skb)
  {
  	u32 count;
  	u32 written;
  	u32 offset;
  	u32 len;
  
  	len = skb->len;
  
  	qcaspi_write_register(qca, SPI_REG_BFR_SIZE, len);
  	if (qca->legacy_mode)
  		qcaspi_tx_cmd(qca, QCA7K_SPI_WRITE | QCA7K_SPI_EXTERNAL);
  
  	offset = 0;
  	while (len) {
  		count = len;
  		if (count > qca->burst_len)
  			count = qca->burst_len;
  
  		if (qca->legacy_mode) {
  			written = qcaspi_write_legacy(qca,
  						      skb->data + offset,
  						      count);
  		} else {
  			written = qcaspi_write_burst(qca,
  						     skb->data + offset,
  						     count);
  		}
  
  		if (written != count)
  			return -1;
  
  		offset += count;
  		len -= count;
  	}
  
  	return 0;
  }
  
  static int
  qcaspi_transmit(struct qcaspi *qca)
  {
  	struct net_device_stats *n_stats = &qca->net_dev->stats;
  	u16 available = 0;
  	u32 pkt_len;
  	u16 new_head;
  	u16 packets = 0;
  
  	if (qca->txr.skb[qca->txr.head] == NULL)
  		return 0;
  
  	qcaspi_read_register(qca, SPI_REG_WRBUF_SPC_AVA, &available);
  
  	while (qca->txr.skb[qca->txr.head]) {
  		pkt_len = qca->txr.skb[qca->txr.head]->len + QCASPI_HW_PKT_LEN;
  
  		if (available < pkt_len) {
  			if (packets == 0)
  				qca->stats.write_buf_miss++;
  			break;
  		}
  
  		if (qcaspi_tx_frame(qca, qca->txr.skb[qca->txr.head]) == -1) {
  			qca->stats.write_err++;
  			return -1;
  		}
  
  		packets++;
  		n_stats->tx_packets++;
  		n_stats->tx_bytes += qca->txr.skb[qca->txr.head]->len;
  		available -= pkt_len;
  
  		/* remove the skb from the queue */
  		/* XXX After inconsistent lock states netif_tx_lock()
  		 * has been replaced by netif_tx_lock_bh() and so on.
  		 */
  		netif_tx_lock_bh(qca->net_dev);
  		dev_kfree_skb(qca->txr.skb[qca->txr.head]);
  		qca->txr.skb[qca->txr.head] = NULL;
  		qca->txr.size -= pkt_len;
  		new_head = qca->txr.head + 1;
  		if (new_head >= qca->txr.count)
  			new_head = 0;
  		qca->txr.head = new_head;
  		if (netif_queue_stopped(qca->net_dev))
  			netif_wake_queue(qca->net_dev);
  		netif_tx_unlock_bh(qca->net_dev);
  	}
  
  	return 0;
  }
  
  static int
  qcaspi_receive(struct qcaspi *qca)
  {
  	struct net_device *net_dev = qca->net_dev;
  	struct net_device_stats *n_stats = &net_dev->stats;
  	u16 available = 0;
  	u32 bytes_read;
  	u8 *cp;
  
  	/* Allocate rx SKB if we don't have one available. */
  	if (!qca->rx_skb) {
  		qca->rx_skb = netdev_alloc_skb_ip_align(net_dev,
  							net_dev->mtu +
  							VLAN_ETH_HLEN);
  		if (!qca->rx_skb) {
  			netdev_dbg(net_dev, "out of RX resources\n");
  			qca->stats.out_of_mem++;
  			return -1;
  		}
  	}
  
  	/* Read the packet size. */
  	qcaspi_read_register(qca, SPI_REG_RDBUF_BYTE_AVA, &available);
  	netdev_dbg(net_dev, "qcaspi_receive: SPI_REG_RDBUF_BYTE_AVA: Value: %08x\n",
  		   available);
  
  	if (available == 0) {
  		netdev_dbg(net_dev, "qcaspi_receive called without any data being available!\n");
  		return -1;
  	}
  
  	qcaspi_write_register(qca, SPI_REG_BFR_SIZE, available);
  
  	if (qca->legacy_mode)
  		qcaspi_tx_cmd(qca, QCA7K_SPI_READ | QCA7K_SPI_EXTERNAL);
  
  	while (available) {
  		u32 count = available;
  
  		if (count > qca->burst_len)
  			count = qca->burst_len;
  
  		if (qca->legacy_mode) {
  			bytes_read = qcaspi_read_legacy(qca, qca->rx_buffer,
  							count);
  		} else {
  			bytes_read = qcaspi_read_burst(qca, qca->rx_buffer,
  						       count);
  		}
  
  		netdev_dbg(net_dev, "available: %d, byte read: %d\n",
  			   available, bytes_read);
  
  		if (bytes_read) {
  			available -= bytes_read;
  		} else {
  			qca->stats.read_err++;
  			return -1;
  		}
  
  		cp = qca->rx_buffer;
  
  		while ((bytes_read--) && (qca->rx_skb)) {
  			s32 retcode;
  
  			retcode = qcafrm_fsm_decode(&qca->frm_handle,
  						    qca->rx_skb->data,
  						    skb_tailroom(qca->rx_skb),
  						    *cp);
  			cp++;
  			switch (retcode) {
  			case QCAFRM_GATHER:
  			case QCAFRM_NOHEAD:
  				break;
  			case QCAFRM_NOTAIL:
  				netdev_dbg(net_dev, "no RX tail\n");
  				n_stats->rx_errors++;
  				n_stats->rx_dropped++;
  				break;
  			case QCAFRM_INVLEN:
  				netdev_dbg(net_dev, "invalid RX length\n");
  				n_stats->rx_errors++;
  				n_stats->rx_dropped++;
  				break;
  			default:
  				qca->rx_skb->dev = qca->net_dev;
  				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(net_dev,
  					net_dev->mtu + VLAN_ETH_HLEN);
  				if (!qca->rx_skb) {
  					netdev_dbg(net_dev, "out of RX resources\n");
  					n_stats->rx_errors++;
  					qca->stats.out_of_mem++;
  					break;
  				}
  			}
  		}
  	}
  
  	return 0;
  }
  
  /*   Check that tx ring stores only so much bytes
   *   that fit into the internal QCA buffer.
   */
  
  static int
  qcaspi_tx_ring_has_space(struct tx_ring *txr)
  {
  	if (txr->skb[txr->tail])
  		return 0;
  
  	return (txr->size + QCAFRM_MAX_LEN < QCASPI_HW_BUF_LEN) ? 1 : 0;
  }
  
  /*   Flush the tx ring. This function is only safe to
   *   call from the qcaspi_spi_thread.
   */
  
  static void
  qcaspi_flush_tx_ring(struct qcaspi *qca)
  {
  	int i;
  
  	/* XXX After inconsistent lock states netif_tx_lock()
  	 * has been replaced by netif_tx_lock_bh() and so on.
  	 */
  	netif_tx_lock_bh(qca->net_dev);
  	for (i = 0; i < TX_RING_MAX_LEN; i++) {
  		if (qca->txr.skb[i]) {
  			dev_kfree_skb(qca->txr.skb[i]);
  			qca->txr.skb[i] = NULL;
  			qca->net_dev->stats.tx_dropped++;
  		}
  	}
  	qca->txr.tail = 0;
  	qca->txr.head = 0;
  	qca->txr.size = 0;
  	netif_tx_unlock_bh(qca->net_dev);
  }
  
  static void
  qcaspi_qca7k_sync(struct qcaspi *qca, int event)
  {
  	u16 signature = 0;
  	u16 spi_config;
  	u16 wrbuf_space = 0;
  	static u16 reset_count;
  
  	if (event == QCASPI_EVENT_CPUON) {
  		/* Read signature twice, if not valid
  		 * go back to unknown state.
  		 */
  		qcaspi_read_register(qca, SPI_REG_SIGNATURE, &signature);
  		qcaspi_read_register(qca, SPI_REG_SIGNATURE, &signature);
  		if (signature != QCASPI_GOOD_SIGNATURE) {
  			qca->sync = QCASPI_SYNC_UNKNOWN;
  			netdev_dbg(qca->net_dev, "sync: got CPU on, but signature was invalid, restart\n");
  		} else {
  			/* ensure that the WRBUF is empty */
  			qcaspi_read_register(qca, SPI_REG_WRBUF_SPC_AVA,
  					     &wrbuf_space);
  			if (wrbuf_space != QCASPI_HW_BUF_LEN) {
  				netdev_dbg(qca->net_dev, "sync: got CPU on, but wrbuf not empty. reset!\n");
  				qca->sync = QCASPI_SYNC_UNKNOWN;
  			} else {
  				netdev_dbg(qca->net_dev, "sync: got CPU on, now in sync\n");
  				qca->sync = QCASPI_SYNC_READY;
  				return;
  			}
  		}
  	}
  
  	switch (qca->sync) {
  	case QCASPI_SYNC_READY:
  		/* Read signature, if not valid go to unknown state. */
  		qcaspi_read_register(qca, SPI_REG_SIGNATURE, &signature);
  		if (signature != QCASPI_GOOD_SIGNATURE) {
  			qca->sync = QCASPI_SYNC_UNKNOWN;
  			netdev_dbg(qca->net_dev, "sync: bad signature, restart\n");
  			/* don't reset right away */
  			return;
  		}
  		break;
  	case QCASPI_SYNC_UNKNOWN:
  		/* Read signature, if not valid stay in unknown state */
  		qcaspi_read_register(qca, SPI_REG_SIGNATURE, &signature);
  		if (signature != QCASPI_GOOD_SIGNATURE) {
  			netdev_dbg(qca->net_dev, "sync: could not read signature to reset device, retry.\n");
  			return;
  		}
  
  		/* TODO: use GPIO to reset QCA7000 in legacy mode*/
  		netdev_dbg(qca->net_dev, "sync: resetting device.\n");
  		qcaspi_read_register(qca, SPI_REG_SPI_CONFIG, &spi_config);
  		spi_config |= QCASPI_SLAVE_RESET_BIT;
  		qcaspi_write_register(qca, SPI_REG_SPI_CONFIG, spi_config);
  
  		qca->sync = QCASPI_SYNC_RESET;
  		qca->stats.trig_reset++;
  		reset_count = 0;
  		break;
  	case QCASPI_SYNC_RESET:
  		reset_count++;
  		netdev_dbg(qca->net_dev, "sync: waiting for CPU on, count %u.\n",
  			   reset_count);
  		if (reset_count >= QCASPI_RESET_TIMEOUT) {
  			/* reset did not seem to take place, try again */
  			qca->sync = QCASPI_SYNC_UNKNOWN;
  			qca->stats.reset_timeout++;
  			netdev_dbg(qca->net_dev, "sync: reset timeout, restarting process.\n");
  		}
  		break;
  	}
  }
  
  static int
  qcaspi_spi_thread(void *data)
  {
  	struct qcaspi *qca = data;
  	u16 intr_cause = 0;
  
  	netdev_info(qca->net_dev, "SPI thread created\n");
  	while (!kthread_should_stop()) {
  		set_current_state(TASK_INTERRUPTIBLE);
  		if ((qca->intr_req == qca->intr_svc) &&
  		    (qca->txr.skb[qca->txr.head] == NULL) &&
  		    (qca->sync == QCASPI_SYNC_READY))
  			schedule();
  
  		set_current_state(TASK_RUNNING);
  
  		netdev_dbg(qca->net_dev, "have work to do. int: %d, tx_skb: %p\n",
  			   qca->intr_req - qca->intr_svc,
  			   qca->txr.skb[qca->txr.head]);
  
  		qcaspi_qca7k_sync(qca, QCASPI_EVENT_UPDATE);
  
  		if (qca->sync != QCASPI_SYNC_READY) {
  			netdev_dbg(qca->net_dev, "sync: not ready %u, turn off carrier and flush\n",
  				   (unsigned int)qca->sync);
  			netif_stop_queue(qca->net_dev);
  			netif_carrier_off(qca->net_dev);
  			qcaspi_flush_tx_ring(qca);
  			msleep(QCASPI_QCA7K_REBOOT_TIME_MS);
  		}
  
  		if (qca->intr_svc != qca->intr_req) {
  			qca->intr_svc = qca->intr_req;
  			start_spi_intr_handling(qca, &intr_cause);
  
  			if (intr_cause & SPI_INT_CPU_ON) {
  				qcaspi_qca7k_sync(qca, QCASPI_EVENT_CPUON);
  
  				/* not synced. */
  				if (qca->sync != QCASPI_SYNC_READY)
  					continue;
  
  				qca->stats.device_reset++;
  				netif_wake_queue(qca->net_dev);
  				netif_carrier_on(qca->net_dev);
  			}
  
  			if (intr_cause & SPI_INT_RDBUF_ERR) {
  				/* restart sync */
  				netdev_dbg(qca->net_dev, "===> rdbuf error!\n");
  				qca->stats.read_buf_err++;
  				qca->sync = QCASPI_SYNC_UNKNOWN;
  				continue;
  			}
  
  			if (intr_cause & SPI_INT_WRBUF_ERR) {
  				/* restart sync */
  				netdev_dbg(qca->net_dev, "===> wrbuf error!\n");
  				qca->stats.write_buf_err++;
  				qca->sync = QCASPI_SYNC_UNKNOWN;
  				continue;
  			}
  
  			/* can only handle other interrupts
  			 * if sync has occurred
  			 */
  			if (qca->sync == QCASPI_SYNC_READY) {
  				if (intr_cause & SPI_INT_PKT_AVLBL)
  					qcaspi_receive(qca);
  			}
  
  			end_spi_intr_handling(qca, intr_cause);
  		}
  
  		if (qca->sync == QCASPI_SYNC_READY)
  			qcaspi_transmit(qca);
  	}
  	set_current_state(TASK_RUNNING);
  	netdev_info(qca->net_dev, "SPI thread exit\n");
  
  	return 0;
  }
  
  static irqreturn_t
  qcaspi_intr_handler(int irq, void *data)
  {
  	struct qcaspi *qca = data;
  
  	qca->intr_req++;
  	if (qca->spi_thread &&
  	    qca->spi_thread->state != TASK_RUNNING)
  		wake_up_process(qca->spi_thread);
  
  	return IRQ_HANDLED;
  }
  
  static int
  qcaspi_netdev_open(struct net_device *dev)
  {
  	struct qcaspi *qca = netdev_priv(dev);
  	int ret = 0;
  
  	if (!qca)
  		return -EINVAL;
  
  	qca->intr_req = 1;
  	qca->intr_svc = 0;
  	qca->sync = QCASPI_SYNC_UNKNOWN;
  	qcafrm_fsm_init_spi(&qca->frm_handle);
  
  	qca->spi_thread = kthread_run((void *)qcaspi_spi_thread,
  				      qca, "%s", dev->name);
  
  	if (IS_ERR(qca->spi_thread)) {
  		netdev_err(dev, "%s: unable to start kernel thread.\n",
  			   QCASPI_DRV_NAME);
  		return PTR_ERR(qca->spi_thread);
  	}
  
  	ret = request_irq(qca->spi_dev->irq, qcaspi_intr_handler, 0,
  			  dev->name, qca);
  	if (ret) {
  		netdev_err(dev, "%s: unable to get IRQ %d (irqval=%d).\n",
  			   QCASPI_DRV_NAME, qca->spi_dev->irq, ret);
  		kthread_stop(qca->spi_thread);
  		return ret;
  	}
  
  	/* SPI thread takes care of TX queue */
  
  	return 0;
  }
  
  static int
  qcaspi_netdev_close(struct net_device *dev)
  {
  	struct qcaspi *qca = netdev_priv(dev);
  
  	netif_stop_queue(dev);
  
  	qcaspi_write_register(qca, SPI_REG_INTR_ENABLE, 0);
  	free_irq(qca->spi_dev->irq, qca);
  
  	kthread_stop(qca->spi_thread);
  	qca->spi_thread = NULL;
  	qcaspi_flush_tx_ring(qca);
  
  	return 0;
  }
  
  static netdev_tx_t
  qcaspi_netdev_xmit(struct sk_buff *skb, struct net_device *dev)
  {
  	u32 frame_len;
  	u8 *ptmp;
  	struct qcaspi *qca = netdev_priv(dev);
  	u16 new_tail;
  	struct sk_buff *tskb;
  	u8 pad_len = 0;
  
  	if (skb->len < QCAFRM_MIN_LEN)
  		pad_len = QCAFRM_MIN_LEN - skb->len;
  
  	if (qca->txr.skb[qca->txr.tail]) {
  		netdev_warn(qca->net_dev, "queue was unexpectedly full!\n");
  		netif_stop_queue(qca->net_dev);
  		qca->stats.ring_full++;
  		return NETDEV_TX_BUSY;
  	}
  
  	if ((skb_headroom(skb) < QCAFRM_HEADER_LEN) ||
  	    (skb_tailroom(skb) < QCAFRM_FOOTER_LEN + pad_len)) {
  		tskb = skb_copy_expand(skb, QCAFRM_HEADER_LEN,
  				       QCAFRM_FOOTER_LEN + pad_len, GFP_ATOMIC);
  		if (!tskb) {
  			qca->stats.out_of_mem++;
  			return NETDEV_TX_BUSY;
  		}
  		dev_kfree_skb(skb);
  		skb = tskb;
  	}
  
  	frame_len = skb->len + pad_len;
  
  	ptmp = skb_push(skb, QCAFRM_HEADER_LEN);
  	qcafrm_create_header(ptmp, frame_len);
  
  	if (pad_len) {
  		ptmp = skb_put_zero(skb, pad_len);
  	}
  
  	ptmp = skb_put(skb, QCAFRM_FOOTER_LEN);
  	qcafrm_create_footer(ptmp);
  
  	netdev_dbg(qca->net_dev, "Tx-ing packet: Size: 0x%08x\n",
  		   skb->len);
  
  	qca->txr.size += skb->len + QCASPI_HW_PKT_LEN;
  
  	new_tail = qca->txr.tail + 1;
  	if (new_tail >= qca->txr.count)
  		new_tail = 0;
  
  	qca->txr.skb[qca->txr.tail] = skb;
  	qca->txr.tail = new_tail;
  
  	if (!qcaspi_tx_ring_has_space(&qca->txr)) {
  		netif_stop_queue(qca->net_dev);
  		qca->stats.ring_full++;
  	}
  
  	netif_trans_update(dev);
  
  	if (qca->spi_thread &&
  	    qca->spi_thread->state != TASK_RUNNING)
  		wake_up_process(qca->spi_thread);
  
  	return NETDEV_TX_OK;
  }
  
  static void
  qcaspi_netdev_tx_timeout(struct net_device *dev)
  {
  	struct qcaspi *qca = netdev_priv(dev);
  
  	netdev_info(qca->net_dev, "Transmit timeout at %ld, latency %ld\n",
  		    jiffies, jiffies - dev_trans_start(dev));
  	qca->net_dev->stats.tx_errors++;
  	/* Trigger tx queue flush and QCA7000 reset */
  	qca->sync = QCASPI_SYNC_UNKNOWN;
  
  	if (qca->spi_thread)
  		wake_up_process(qca->spi_thread);
  }
  
  static int
  qcaspi_netdev_init(struct net_device *dev)
  {
  	struct qcaspi *qca = netdev_priv(dev);
  
  	dev->mtu = QCAFRM_MAX_MTU;
  	dev->type = ARPHRD_ETHER;
  	qca->clkspeed = qcaspi_clkspeed;
  	qca->burst_len = qcaspi_burst_len;
  	qca->spi_thread = NULL;
  	qca->buffer_size = (dev->mtu + VLAN_ETH_HLEN + QCAFRM_HEADER_LEN +
  		QCAFRM_FOOTER_LEN + 4) * 4;
  
  	memset(&qca->stats, 0, sizeof(struct qcaspi_stats));
  
  	qca->rx_buffer = kmalloc(qca->buffer_size, GFP_KERNEL);
  	if (!qca->rx_buffer)
  		return -ENOBUFS;
  
  	qca->rx_skb = netdev_alloc_skb_ip_align(dev, qca->net_dev->mtu +
  						VLAN_ETH_HLEN);
  	if (!qca->rx_skb) {
  		kfree(qca->rx_buffer);
  		netdev_info(qca->net_dev, "Failed to allocate RX sk_buff.\n");
  		return -ENOBUFS;
  	}
  
  	return 0;
  }
  
  static void
  qcaspi_netdev_uninit(struct net_device *dev)
  {
  	struct qcaspi *qca = netdev_priv(dev);
  
  	kfree(qca->rx_buffer);
  	qca->buffer_size = 0;
  	if (qca->rx_skb)
  		dev_kfree_skb(qca->rx_skb);
  }
  
  static const struct net_device_ops qcaspi_netdev_ops = {
  	.ndo_init = qcaspi_netdev_init,
  	.ndo_uninit = qcaspi_netdev_uninit,
  	.ndo_open = qcaspi_netdev_open,
  	.ndo_stop = qcaspi_netdev_close,
  	.ndo_start_xmit = qcaspi_netdev_xmit,
  	.ndo_set_mac_address = eth_mac_addr,
  	.ndo_tx_timeout = qcaspi_netdev_tx_timeout,
  	.ndo_validate_addr = eth_validate_addr,
  };
  
  static void
  qcaspi_netdev_setup(struct net_device *dev)
  {
  	struct qcaspi *qca = NULL;
  
  	dev->netdev_ops = &qcaspi_netdev_ops;
  	qcaspi_set_ethtool_ops(dev);
  	dev->watchdog_timeo = QCASPI_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;
  
  	qca = netdev_priv(dev);
  	memset(qca, 0, sizeof(struct qcaspi));
  
  	memset(&qca->txr, 0, sizeof(qca->txr));
  	qca->txr.count = TX_RING_MAX_LEN;
  }
  
  static const struct of_device_id qca_spi_of_match[] = {
  	{ .compatible = "qca,qca7000" },
  	{ /* sentinel */ }
  };
  MODULE_DEVICE_TABLE(of, qca_spi_of_match);
  
  static int
  qca_spi_probe(struct spi_device *spi)
  {
  	struct qcaspi *qca = NULL;
  	struct net_device *qcaspi_devs = NULL;
  	u8 legacy_mode = 0;
  	u16 signature;
  	const char *mac;
  
  	if (!spi->dev.of_node) {
  		dev_err(&spi->dev, "Missing device tree\n");
  		return -EINVAL;
  	}
  
  	legacy_mode = of_property_read_bool(spi->dev.of_node,
  					    "qca,legacy-mode");
  
  	if (qcaspi_clkspeed == 0) {
  		if (spi->max_speed_hz)
  			qcaspi_clkspeed = spi->max_speed_hz;
  		else
  			qcaspi_clkspeed = QCASPI_CLK_SPEED;
  	}
  
  	if ((qcaspi_clkspeed < QCASPI_CLK_SPEED_MIN) ||
  	    (qcaspi_clkspeed > QCASPI_CLK_SPEED_MAX)) {
  		dev_err(&spi->dev, "Invalid clkspeed: %d\n",
  			qcaspi_clkspeed);
  		return -EINVAL;
  	}
  
  	if ((qcaspi_burst_len < QCASPI_BURST_LEN_MIN) ||
  	    (qcaspi_burst_len > QCASPI_BURST_LEN_MAX)) {
  		dev_err(&spi->dev, "Invalid burst len: %d\n",
  			qcaspi_burst_len);
  		return -EINVAL;
  	}
  
  	if ((qcaspi_pluggable < QCASPI_PLUGGABLE_MIN) ||
  	    (qcaspi_pluggable > QCASPI_PLUGGABLE_MAX)) {
  		dev_err(&spi->dev, "Invalid pluggable: %d\n",
  			qcaspi_pluggable);
  		return -EINVAL;
  	}
  
  	dev_info(&spi->dev, "ver=%s, clkspeed=%d, burst_len=%d, pluggable=%d\n",
  		 QCASPI_DRV_VERSION,
  		 qcaspi_clkspeed,
  		 qcaspi_burst_len,
  		 qcaspi_pluggable);
  
  	spi->mode = SPI_MODE_3;
  	spi->max_speed_hz = qcaspi_clkspeed;
  	if (spi_setup(spi) < 0) {
  		dev_err(&spi->dev, "Unable to setup SPI device\n");
  		return -EFAULT;
  	}
  
  	qcaspi_devs = alloc_etherdev(sizeof(struct qcaspi));
  	if (!qcaspi_devs)
  		return -ENOMEM;
  
  	qcaspi_netdev_setup(qcaspi_devs);
  	SET_NETDEV_DEV(qcaspi_devs, &spi->dev);
  
  	qca = netdev_priv(qcaspi_devs);
  	if (!qca) {
  		free_netdev(qcaspi_devs);
  		dev_err(&spi->dev, "Fail to retrieve private structure\n");
  		return -ENOMEM;
  	}
  	qca->net_dev = qcaspi_devs;
  	qca->spi_dev = spi;
  	qca->legacy_mode = legacy_mode;
  
  	spi_set_drvdata(spi, qcaspi_devs);
  
  	mac = of_get_mac_address(spi->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(&spi->dev, "Using random MAC address: %pM\n",
  			 qca->net_dev->dev_addr);
  	}
  
  	netif_carrier_off(qca->net_dev);
  
  	if (!qcaspi_pluggable) {
  		qcaspi_read_register(qca, SPI_REG_SIGNATURE, &signature);
  		qcaspi_read_register(qca, SPI_REG_SIGNATURE, &signature);
  
  		if (signature != QCASPI_GOOD_SIGNATURE) {
  			dev_err(&spi->dev, "Invalid signature (0x%04X)\n",
  				signature);
  			free_netdev(qcaspi_devs);
  			return -EFAULT;
  		}
  	}
  
  	if (register_netdev(qcaspi_devs)) {
  		dev_err(&spi->dev, "Unable to register net device %s\n",
  			qcaspi_devs->name);
  		free_netdev(qcaspi_devs);
  		return -EFAULT;
  	}
  
  	qcaspi_init_device_debugfs(qca);
  
  	return 0;
  }
  
  static int
  qca_spi_remove(struct spi_device *spi)
  {
  	struct net_device *qcaspi_devs = spi_get_drvdata(spi);
  	struct qcaspi *qca = netdev_priv(qcaspi_devs);
  
  	qcaspi_remove_device_debugfs(qca);
  
  	unregister_netdev(qcaspi_devs);
  	free_netdev(qcaspi_devs);
  
  	return 0;
  }
  
  static const struct spi_device_id qca_spi_id[] = {
  	{ "qca7000", 0 },
  	{ /* sentinel */ }
  };
  MODULE_DEVICE_TABLE(spi, qca_spi_id);
  
  static struct spi_driver qca_spi_driver = {
  	.driver	= {
  		.name	= QCASPI_DRV_NAME,
  		.of_match_table = qca_spi_of_match,
  	},
  	.id_table = qca_spi_id,
  	.probe    = qca_spi_probe,
  	.remove   = qca_spi_remove,
  };
  module_spi_driver(qca_spi_driver);
  
  MODULE_DESCRIPTION("Qualcomm Atheros QCA7000 SPI Driver");
  MODULE_AUTHOR("Qualcomm Atheros Communications");
  MODULE_AUTHOR("Stefan Wahren <stefan.wahren@i2se.com>");
  MODULE_LICENSE("Dual BSD/GPL");
  MODULE_VERSION(QCASPI_DRV_VERSION);
  