net: qualcomm: add QCA7000 UART driver

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

Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
Reviewed-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

4 files changed, 447 insertions, 0 deletions

diff --git a/drivers/net/ethernet/qualcomm/Kconfig b/drivers/net/ethernet/qualcomm/Kconfig
index b4c369dccde7..877675a27b9f 100644
--- a/drivers/net/ethernet/qualcomm/Kconfig
+++ b/drivers/net/ethernet/qualcomm/Kconfig
@@ -30,6 +30,22 @@ 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 SERIAL_DEV_BUS && OF
+        ---help---
+          This UART protocol driver supports the Qualcomm Atheros QCA7000.
+
+          Currently the driver assumes these device UART settings:
+            Data bits: 8
+            Parity: None
+            Stop bits: 1
+            Flow control: None
+
+          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"
         depends on HAS_DMA && HAS_IOMEM
diff --git a/drivers/net/ethernet/qualcomm/Makefile b/drivers/net/ethernet/qualcomm/Makefile
index 65556ca185a6..92fa7c4da90a 100644
--- a/drivers/net/ethernet/qualcomm/Makefile
+++ b/drivers/net/ethernet/qualcomm/Makefile
@@ -5,5 +5,7 @@
 obj-$(CONFIG_QCA7000) += qca_7k_common.o
 obj-$(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_7k_common.h b/drivers/net/ethernet/qualcomm/qca_7k_common.h
index 07bdd6c4f728..928554f11e35 100644
--- a/drivers/net/ethernet/qualcomm/qca_7k_common.h
+++ b/drivers/net/ethernet/qualcomm/qca_7k_common.h
@@ -122,6 +122,12 @@ 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 000000000000..db6068cd7a1f
--- /dev/null
+++ b/drivers/net/ethernet/qualcomm/qca_uart.c
@@ -0,0 +1,423 @@
+/*
+ *   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);