[PATCH net-next 8/8] net: qualcomm: add QCA7000 UART driver

[Stefan Wahren]

This patch adds the Ethernet over UART driver for the
Qualcomm QCA7000 HomePlug GreenPHY.

Signed-off-by: Stefan Wahren <stefan.wahren@xxxxxxxx>
---
 drivers/net/ethernet/qualcomm/Kconfig      |  12 +
 drivers/net/ethernet/qualcomm/Makefile     |   2 +
 drivers/net/ethernet/qualcomm/qca_common.h |   6 +
 drivers/net/ethernet/qualcomm/qca_uart.c   | 447 +++++++++++++++++++++++++++++
 include/uapi/linux/tty.h                   |   1 +
 5 files changed, 468 insertions(+)
 create mode 100644 drivers/net/ethernet/qualcomm/qca_uart.c

diff --git a/drivers/net/ethernet/qualcomm/Kconfig b/drivers/net/ethernet/qualcomm/Kconfig
index 0d33728..0ede46e 100644
--- a/drivers/net/ethernet/qualcomm/Kconfig
+++ b/drivers/net/ethernet/qualcomm/Kconfig
@@ -30,6 +30,18 @@ config QCA7000_SPI
 	  To compile this driver as a module, choose M here. The module
 	  will be called qcaspi.
 
+config QCA7000_UART
+	tristate "Qualcomm Atheros QCA7000 UART support"
+	select QCA7000
+	depends on TTY
+	---help---
+	  This UART protocol driver supports the Qualcomm Atheros QCA7000.
+	  The driver implements the tty line discipline N_QCA7K and supports
+	  only one netdevice.
+
+	  To compile this driver as a module, choose M here. The module
+	  will be called qcauart.
+
 config QCOM_EMAC
 	tristate "Qualcomm Technologies, Inc. EMAC Gigabit Ethernet support"
 	select CRC32
diff --git a/drivers/net/ethernet/qualcomm/Makefile b/drivers/net/ethernet/qualcomm/Makefile
index 00d8729..8847db7 100644
--- a/drivers/net/ethernet/qualcomm/Makefile
+++ b/drivers/net/ethernet/qualcomm/Makefile
@@ -5,5 +5,7 @@
 obj-$(CONFIG_QCA7000) += qca_common.o
 obj-$(CONFIG_QCA7000_SPI) += qcaspi.o
 qcaspi-objs := qca_7k.o qca_debug.o qca_spi.o
+obj-$(CONFIG_QCA7000_UART) += qcauart.o
+qcauart-objs := qca_uart.o
 
 obj-y += emac/
diff --git a/drivers/net/ethernet/qualcomm/qca_common.h b/drivers/net/ethernet/qualcomm/qca_common.h
index c93cfdf07..bc38689 100644
--- a/drivers/net/ethernet/qualcomm/qca_common.h
+++ b/drivers/net/ethernet/qualcomm/qca_common.h
@@ -123,6 +123,12 @@ static inline void qcafrm_fsm_init_spi(struct qcafrm_handle *handle)
 	handle->state = handle->init;
 }
 
+static inline void qcafrm_fsm_init_uart(struct qcafrm_handle *handle)
+{
+	handle->init = QCAFRM_WAIT_AA1;
+	handle->state = handle->init;
+}
+
 /*   Gather received bytes and try to extract a full Ethernet frame
  *   by following a simple state machine.
  *
diff --git a/drivers/net/ethernet/qualcomm/qca_uart.c b/drivers/net/ethernet/qualcomm/qca_uart.c
new file mode 100644
index 0000000..f956c83
--- /dev/null
+++ b/drivers/net/ethernet/qualcomm/qca_uart.c
@@ -0,0 +1,447 @@
+/*
+ *   Copyright (c) 2011, 2012, Qualcomm Atheros Communications Inc.
+ *   Copyright (c) 2016, 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/errno.h>
+#include <linux/etherdevice.h>
+#include <linux/if_arp.h>
+#include <linux/if_ether.h>
+#include <linux/init.h>
+#include <linux/jiffies.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/netdevice.h>
+#include <linux/sched.h>
+#include <linux/skbuff.h>
+#include <linux/tty.h>
+#include <linux/types.h>
+
+#include "qca_common.h"
+
+#define QCAUART_DRV_VERSION "0.0.6"
+#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 tty_struct *tty;
+
+	unsigned char xbuff[QCAFRM_ETHMAXMTU];	/* transmitter buffer        */
+	unsigned char *xhead;			/* pointer to next XMIT byte */
+	int xleft;				/* bytes left in XMIT queue  */
+
+	struct qcafrm_handle frm_handle;
+
+	struct sk_buff *rx_skb;
+};
+
+static struct net_device *qcauart_dev;
+
+void
+qca_tty_receive(struct tty_struct *tty, const unsigned char *cp, char *fp,
+		int count)
+{
+	struct qcauart *qca = tty->disc_data;
+	struct net_device_stats *n_stats = &qca->net_dev->stats;
+	int dropped = 0;
+
+	if (!qca->rx_skb) {
+		qca->rx_skb = netdev_alloc_skb(qca->net_dev, qca->net_dev->mtu +
+					       VLAN_ETH_HLEN);
+		if (!qca->rx_skb) {
+			n_stats->rx_errors++;
+			n_stats->rx_dropped++;
+			return;
+		}
+	}
+
+	while (count--) {
+		s32 retcode;
+
+		if (fp && *fp++) {
+			n_stats->rx_errors++;
+			cp++;
+			dropped++;
+			continue;
+		}
+
+		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(qca->net_dev, "recv: no RX tail\n");
+			n_stats->rx_errors++;
+			n_stats->rx_dropped++;
+			break;
+		case QCAFRM_INVLEN:
+			netdev_dbg(qca->net_dev, "recv: 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(qca->net_dev,
+						       qca->net_dev->mtu +
+						       VLAN_ETH_HLEN);
+			if (!qca->rx_skb) {
+				netdev_dbg(qca->net_dev, "recv: out of RX resources\n");
+				n_stats->rx_errors++;
+				break;
+			}
+		}
+	}
+
+	if (dropped)
+		dev_dbg_ratelimited(&qca->net_dev->dev, "recv: invalid %d bytes\n",
+				    dropped);
+}
+
+/* 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 (!qca->tty || !netif_running(qca->net_dev)) {
+		spin_unlock_bh(&qca->lock);
+		return;
+	}
+
+	if (qca->xleft <= 0)  {
+		/* Now serial buffer is almost free & we can start
+		 * transmission of another packet
+		 */
+		n_stats->tx_packets++;
+		clear_bit(TTY_DO_WRITE_WAKEUP, &qca->tty->flags);
+		spin_unlock_bh(&qca->lock);
+		netif_wake_queue(qca->net_dev);
+		return;
+	}
+
+	written = qca->tty->ops->write(qca->tty, qca->xhead, qca->xleft);
+	qca->xleft -= written;
+	qca->xhead += 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 tty_struct *tty)
+{
+	struct qcauart *qca = tty->disc_data;
+
+	schedule_work(&qca->tx_work);
+}
+
+int
+qca_tty_open(struct tty_struct *tty)
+{
+	struct qcauart *qca;
+
+	if (!capable(CAP_NET_ADMIN))
+		return -EPERM;
+
+	if (!tty->ops->write)
+		return -EOPNOTSUPP;
+
+	if (tty->disc_data)
+		return -EEXIST;
+
+	qca = netdev_priv(qcauart_dev);
+	qca->tty = tty;
+	tty->disc_data = qca;
+	tty->receive_room = 4096;
+	netif_carrier_on(qca->net_dev);
+
+	return 0;
+}
+
+void
+qca_tty_close(struct tty_struct *tty)
+{
+	struct qcauart *qca = (void *)tty->disc_data;
+
+	if (!qca)
+		return;
+
+	netif_carrier_off(qca->net_dev);
+	qca->tty = NULL;
+
+	/* Detach from the tty */
+	tty->disc_data = NULL;
+}
+
+static struct tty_ldisc_ops qca_ldisc = {
+	.owner  = THIS_MODULE,
+	.magic	= TTY_LDISC_MAGIC,
+	.name	= "qca",
+	.open	= qca_tty_open,
+	.close	= qca_tty_close,
+	.ioctl	= n_tty_ioctl_helper,
+	.receive_buf = qca_tty_receive,
+	.write_wakeup = qca_tty_wakeup,
+};
+
+int
+qcauart_netdev_open(struct net_device *dev)
+{
+	struct qcauart *qca = netdev_priv(dev);
+
+	qcafrm_fsm_init_uart(&qca->frm_handle);
+	netif_start_queue(qca->net_dev);
+
+	return 0;
+}
+
+int
+qcauart_netdev_close(struct net_device *dev)
+{
+	struct qcauart *qca = netdev_priv(dev);
+
+	spin_lock_bh(&qca->lock);
+	if (qca->tty) {
+		/* TTY discipline is running. */
+		clear_bit(TTY_DO_WRITE_WAKEUP, &qca->tty->flags);
+	}
+	netif_stop_queue(dev);
+	qca->xleft = 0;
+	spin_unlock_bh(&qca->lock);
+
+	return 0;
+}
+
+netdev_tx_t
+qcauart_netdev_xmit(struct sk_buff *skb, struct net_device *dev)
+{
+	struct qcauart *qca = netdev_priv(dev);
+	struct net_device_stats *n_stats = &dev->stats;
+	u8 *pos;
+	u8 pad_len = 0;
+	int written;
+
+	spin_lock(&qca->lock);
+
+	if (!netif_running(dev))  {
+		spin_unlock(&qca->lock);
+		netdev_warn(qca->net_dev, "xmit: iface is down\n");
+		goto out;
+	}
+	if (!qca->tty) {
+		spin_unlock(&qca->lock);
+		goto out;
+	}
+
+	pos = qca->xbuff;
+
+	if (skb->len < QCAFRM_ETHMINLEN)
+		pad_len = QCAFRM_ETHMINLEN - 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);
+
+	set_bit(TTY_DO_WRITE_WAKEUP, &qca->tty->flags);
+	written = qca->tty->ops->write(qca->tty, qca->xbuff, pos - qca->xbuff);
+	qca->xleft = (pos - qca->xbuff) - written;
+	qca->xhead = qca->xbuff + written;
+	n_stats->tx_bytes += written;
+	spin_unlock(&qca->lock);
+
+	dev->trans_start = jiffies;
+out:
+	kfree_skb(skb);
+	return NETDEV_TX_OK;
+}
+
+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, jiffies - dev->trans_start);
+	dev->stats.tx_errors++;
+	dev->stats.tx_dropped++;
+
+	clear_bit(TTY_DO_WRITE_WAKEUP, &qca->tty->flags);
+}
+
+static int
+qcauart_netdev_init(struct net_device *dev)
+{
+	struct qcauart *qca = netdev_priv(dev);
+
+	/* Finish setting up the device info. */
+	dev->mtu = QCAFRM_ETHMAXMTU;
+	dev->type = ARPHRD_ETHER;
+
+	qca->rx_skb = netdev_alloc_skb(qca->net_dev,
+				       qca->net_dev->mtu + VLAN_ETH_HLEN);
+	if (!qca->rx_skb)
+		return -ENOMEM;
+
+	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_change_mtu = qcacmn_netdev_change_mtu,
+	.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)
+{
+	struct qcauart *qca;
+
+	dev->netdev_ops = &qcauart_netdev_ops;
+	dev->watchdog_timeo = QCAUART_TX_TIMEOUT;
+	dev->priv_flags &= ~IFF_TX_SKB_SHARING;
+	dev->tx_queue_len = 100;
+
+	qca = netdev_priv(dev);
+	memset(qca, 0, sizeof(struct qcauart));
+}
+
+static int __init qcauart_mod_init(void)
+{
+	struct qcauart *qca;
+	int ret;
+
+	ret = tty_register_ldisc(N_QCA7K, &qca_ldisc);
+	if (ret) {
+		pr_err("qca_uart: Can't register line discipline (ret %d)\n",
+		       ret);
+		return ret;
+	}
+
+	qcauart_dev = alloc_etherdev(sizeof(struct qcauart));
+	if (!qcauart_dev)
+		return -ENOMEM;
+
+	qcauart_netdev_setup(qcauart_dev);
+
+	qca = netdev_priv(qcauart_dev);
+	if (!qca) {
+		pr_err("qca_uart: Fail to retrieve private structure\n");
+		free_netdev(qcauart_dev);
+		return -ENOMEM;
+	}
+	qca->net_dev = qcauart_dev;
+	spin_lock_init(&qca->lock);
+	INIT_WORK(&qca->tx_work, qcauart_transmit);
+
+	eth_hw_addr_random(qca->net_dev);
+	pr_info("qca_uart: ver=%s, using random MAC address: %pM\n",
+		QCAUART_DRV_VERSION, qca->net_dev->dev_addr);
+
+	netif_carrier_off(qca->net_dev);
+
+	if (register_netdev(qcauart_dev)) {
+		pr_err("qca_uart: Unable to register net device %s\n",
+		       qcauart_dev->name);
+		free_netdev(qcauart_dev);
+		return -EFAULT;
+	}
+
+	return 0;
+}
+
+static void __exit qcauart_mod_exit(void)
+{
+	struct qcauart *qca;
+	int ret;
+
+	qca = netdev_priv(qcauart_dev);
+	spin_lock_bh(&qca->lock);
+	if (qca->tty)
+		tty_hangup(qca->tty);
+	spin_unlock_bh(&qca->lock);
+
+	unregister_netdev(qcauart_dev);
+
+	free_netdev(qcauart_dev);
+	qcauart_dev = NULL;
+
+	ret = tty_unregister_ldisc(N_QCA7K);
+	if (ret)
+		pr_err("qca_uart: can't unregister line discipline (ret %d)\n",
+		       ret);
+}
+
+module_init(qcauart_mod_init);
+module_exit(qcauart_mod_exit);
+
+MODULE_DESCRIPTION("Qualcomm Atheros UART Driver");
+MODULE_AUTHOR("Qualcomm Atheros Communications");
+MODULE_AUTHOR("Stefan Wahren <stefan.wahren@xxxxxxxx>");
+MODULE_LICENSE("Dual BSD/GPL");
+MODULE_VERSION(QCAUART_DRV_VERSION);
+MODULE_ALIAS_LDISC(N_QCA7K);
diff --git a/include/uapi/linux/tty.h b/include/uapi/linux/tty.h
index 01c4410..53c2760 100644
--- a/include/uapi/linux/tty.h
+++ b/include/uapi/linux/tty.h
@@ -35,5 +35,6 @@
 #define N_TRACESINK	23	/* Trace data routing for MIPI P1149.7 */
 #define N_TRACEROUTER	24	/* Trace data routing for MIPI P1149.7 */
 #define N_NCI		25	/* NFC NCI UART */
+#define N_QCA7K		26	/* Qualcomm QCA7000 Ethernet to UART */
 
 #endif /* _UAPI_LINUX_TTY_H */
-- 
2.1.4