1 files changed, 495 insertions, 0 deletions

diff --git a/net/nfc/nci/uart.c b/net/nfc/nci/uart.c
new file mode 100644
index 0000000..cff92db
--- /dev/null
+++ b/net/nfc/nci/uart.c
@@ -0,0 +1,495 @@
+/*
+ * Copyright (C) 2015, Marvell International Ltd.
+ *
+ * This software file (the "File") is distributed by Marvell International
+ * Ltd. under the terms of the GNU General Public License Version 2, June 1991
+ * (the "License").  You may use, redistribute and/or modify this File in
+ * accordance with the terms and conditions of the License, a copy of which
+ * is available on the worldwide web at
+ * http://www.gnu.org/licenses/old-licenses/gpl-2.0.txt.
+ *
+ * THE FILE IS DISTRIBUTED AS-IS, WITHOUT WARRANTY OF ANY KIND, AND THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE
+ * ARE EXPRESSLY DISCLAIMED.  The License provides additional details about
+ * this warranty disclaimer.
+ */
+
+/* Inspired (hugely) by HCI LDISC implementation in Bluetooth.
+ *
+ *  Copyright (C) 2000-2001  Qualcomm Incorporated
+ *  Copyright (C) 2002-2003  Maxim Krasnyansky <maxk@qualcomm.com>
+ *  Copyright (C) 2004-2005  Marcel Holtmann <marcel@holtmann.org>
+ */
+
+#include <linux/module.h>
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/types.h>
+#include <linux/fcntl.h>
+#include <linux/interrupt.h>
+#include <linux/ptrace.h>
+#include <linux/poll.h>
+
+#include <linux/slab.h>
+#include <linux/tty.h>
+#include <linux/errno.h>
+#include <linux/string.h>
+#include <linux/signal.h>
+#include <linux/ioctl.h>
+#include <linux/skbuff.h>
+
+#include <net/nfc/nci.h>
+#include <net/nfc/nci_core.h>
+
+/* TX states  */
+#define NCI_UART_SENDING	1
+#define NCI_UART_TX_WAKEUP	2
+
+static struct nci_uart *nci_uart_drivers[NCI_UART_DRIVER_MAX];
+
+static inline struct sk_buff *nci_uart_dequeue(struct nci_uart *nu)
+{
+	struct sk_buff *skb = nu->tx_skb;
+
+	if (!skb)
+		skb = skb_dequeue(&nu->tx_q);
+	else
+		nu->tx_skb = NULL;
+
+	return skb;
+}
+
+static inline int nci_uart_queue_empty(struct nci_uart *nu)
+{
+	if (nu->tx_skb)
+		return 0;
+
+	return skb_queue_empty(&nu->tx_q);
+}
+
+static int nci_uart_tx_wakeup(struct nci_uart *nu)
+{
+	if (test_and_set_bit(NCI_UART_SENDING, &nu->tx_state)) {
+		set_bit(NCI_UART_TX_WAKEUP, &nu->tx_state);
+		return 0;
+	}
+
+	schedule_work(&nu->write_work);
+
+	return 0;
+}
+
+static void nci_uart_write_work(struct work_struct *work)
+{
+	struct nci_uart *nu = container_of(work, struct nci_uart, write_work);
+	struct tty_struct *tty = nu->tty;
+	struct sk_buff *skb;
+
+restart:
+	clear_bit(NCI_UART_TX_WAKEUP, &nu->tx_state);
+
+	if (nu->ops.tx_start)
+		nu->ops.tx_start(nu);
+
+	while ((skb = nci_uart_dequeue(nu))) {
+		int len;
+
+		set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
+		len = tty->ops->write(tty, skb->data, skb->len);
+		skb_pull(skb, len);
+		if (skb->len) {
+			nu->tx_skb = skb;
+			break;
+		}
+		kfree_skb(skb);
+	}
+
+	if (test_bit(NCI_UART_TX_WAKEUP, &nu->tx_state))
+		goto restart;
+
+	if (nu->ops.tx_done && nci_uart_queue_empty(nu))
+		nu->ops.tx_done(nu);
+
+	clear_bit(NCI_UART_SENDING, &nu->tx_state);
+}
+
+static int nci_uart_set_driver(struct tty_struct *tty, unsigned int driver)
+{
+	struct nci_uart *nu = NULL;
+	int ret;
+
+	if (driver >= NCI_UART_DRIVER_MAX)
+		return -EINVAL;
+
+	if (!nci_uart_drivers[driver])
+		return -ENOENT;
+
+	nu = kzalloc(sizeof(*nu), GFP_KERNEL);
+	if (!nu)
+		return -ENOMEM;
+
+	memcpy(nu, nci_uart_drivers[driver], sizeof(struct nci_uart));
+	nu->tty = tty;
+	tty->disc_data = nu;
+	skb_queue_head_init(&nu->tx_q);
+	INIT_WORK(&nu->write_work, nci_uart_write_work);
+	spin_lock_init(&nu->rx_lock);
+
+	ret = nu->ops.open(nu);
+	if (ret) {
+		tty->disc_data = NULL;
+		kfree(nu);
+	} else if (!try_module_get(nu->owner)) {
+		nu->ops.close(nu);
+		tty->disc_data = NULL;
+		kfree(nu);
+		return -ENOENT;
+	}
+	return ret;
+}
+
+/* ------ LDISC part ------ */
+
+/* nci_uart_tty_open
+ *
+ *     Called when line discipline changed to NCI_UART.
+ *
+ * Arguments:
+ *     tty    pointer to tty info structure
+ * Return Value:
+ *     0 if success, otherwise error code
+ */
+static int nci_uart_tty_open(struct tty_struct *tty)
+{
+	/* Error if the tty has no write op instead of leaving an exploitable
+	 * hole
+	 */
+	if (!tty->ops->write)
+		return -EOPNOTSUPP;
+
+	tty->disc_data = NULL;
+	tty->receive_room = 65536;
+
+	/* Flush any pending characters in the driver */
+	tty_driver_flush_buffer(tty);
+
+	return 0;
+}
+
+/* nci_uart_tty_close()
+ *
+ *    Called when the line discipline is changed to something
+ *    else, the tty is closed, or the tty detects a hangup.
+ */
+static void nci_uart_tty_close(struct tty_struct *tty)
+{
+	struct nci_uart *nu = (void *)tty->disc_data;
+
+	/* Detach from the tty */
+	tty->disc_data = NULL;
+
+	if (!nu)
+		return;
+
+	if (nu->tx_skb)
+		kfree_skb(nu->tx_skb);
+	if (nu->rx_skb)
+		kfree_skb(nu->rx_skb);
+
+	skb_queue_purge(&nu->tx_q);
+
+	nu->ops.close(nu);
+	nu->tty = NULL;
+	module_put(nu->owner);
+
+	cancel_work_sync(&nu->write_work);
+
+	kfree(nu);
+}
+
+/* nci_uart_tty_wakeup()
+ *
+ *    Callback for transmit wakeup. Called when low level
+ *    device driver can accept more send data.
+ *
+ * Arguments:        tty    pointer to associated tty instance data
+ * Return Value:    None
+ */
+static void nci_uart_tty_wakeup(struct tty_struct *tty)
+{
+	struct nci_uart *nu = (void *)tty->disc_data;
+
+	if (!nu)
+		return;
+
+	clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
+
+	if (tty != nu->tty)
+		return;
+
+	nci_uart_tx_wakeup(nu);
+}
+
+/* nci_uart_tty_receive()
+ *
+ *     Called by tty low level driver when receive data is
+ *     available.
+ *
+ * Arguments:  tty          pointer to tty isntance data
+ *             data         pointer to received data
+ *             flags        pointer to flags for data
+ *             count        count of received data in bytes
+ *
+ * Return Value:    None
+ */
+static void nci_uart_tty_receive(struct tty_struct *tty, const u8 *data,
+				 char *flags, int count)
+{
+	struct nci_uart *nu = (void *)tty->disc_data;
+
+	if (!nu || tty != nu->tty)
+		return;
+
+	spin_lock(&nu->rx_lock);
+	nu->ops.recv_buf(nu, (void *)data, flags, count);
+	spin_unlock(&nu->rx_lock);
+
+	tty_unthrottle(tty);
+}
+
+/* nci_uart_tty_ioctl()
+ *
+ *    Process IOCTL system call for the tty device.
+ *
+ * Arguments:
+ *
+ *    tty        pointer to tty instance data
+ *    file       pointer to open file object for device
+ *    cmd        IOCTL command code
+ *    arg        argument for IOCTL call (cmd dependent)
+ *
+ * Return Value:    Command dependent
+ */
+static int nci_uart_tty_ioctl(struct tty_struct *tty, struct file *file,
+			      unsigned int cmd, unsigned long arg)
+{
+	struct nci_uart *nu = (void *)tty->disc_data;
+	int err = 0;
+
+	switch (cmd) {
+	case NCIUARTSETDRIVER:
+		if (!nu)
+			return nci_uart_set_driver(tty, (unsigned int)arg);
+		else
+			return -EBUSY;
+		break;
+	default:
+		err = n_tty_ioctl_helper(tty, file, cmd, arg);
+		break;
+	}
+
+	return err;
+}
+
+/* We don't provide read/write/poll interface for user space. */
+static ssize_t nci_uart_tty_read(struct tty_struct *tty, struct file *file,
+				 unsigned char __user *buf, size_t nr)
+{
+	return 0;
+}
+
+static ssize_t nci_uart_tty_write(struct tty_struct *tty, struct file *file,
+				  const unsigned char *data, size_t count)
+{
+	return 0;
+}
+
+static unsigned int nci_uart_tty_poll(struct tty_struct *tty,
+				      struct file *filp, poll_table *wait)
+{
+	return 0;
+}
+
+static int nci_uart_send(struct nci_uart *nu, struct sk_buff *skb)
+{
+	/* Queue TX packet */
+	skb_queue_tail(&nu->tx_q, skb);
+
+	/* Try to start TX (if possible) */
+	nci_uart_tx_wakeup(nu);
+
+	return 0;
+}
+
+/* -- Default recv_buf handler --
+ *
+ * This handler supposes that NCI frames are sent over UART link without any
+ * framing. It reads NCI header, retrieve the packet size and once all packet
+ * bytes are received it passes it to nci_uart driver for processing.
+ */
+static int nci_uart_default_recv_buf(struct nci_uart *nu, const u8 *data,
+				     char *flags, int count)
+{
+	int chunk_len;
+
+	if (!nu->ndev) {
+		nfc_err(nu->tty->dev,
+			"receive data from tty but no NCI dev is attached yet, drop buffer\n");
+		return 0;
+	}
+
+	/* Decode all incoming data in packets
+	 * and enqueue then for processing.
+	 */
+	while (count > 0) {
+		/* If this is the first data of a packet, allocate a buffer */
+		if (!nu->rx_skb) {
+			nu->rx_packet_len = -1;
+			nu->rx_skb = nci_skb_alloc(nu->ndev,
+						   NCI_MAX_PACKET_SIZE,
+						   GFP_KERNEL);
+			if (!nu->rx_skb)
+				return -ENOMEM;
+		}
+
+		/* Eat byte after byte till full packet header is received */
+		if (nu->rx_skb->len < NCI_CTRL_HDR_SIZE) {
+			*skb_put(nu->rx_skb, 1) = *data++;
+			--count;
+			continue;
+		}
+
+		/* Header was received but packet len was not read */
+		if (nu->rx_packet_len < 0)
+			nu->rx_packet_len = NCI_CTRL_HDR_SIZE +
+				nci_plen(nu->rx_skb->data);
+
+		/* Compute how many bytes are missing and how many bytes can
+		 * be consumed.
+		 */
+		chunk_len = nu->rx_packet_len - nu->rx_skb->len;
+		if (count < chunk_len)
+			chunk_len = count;
+		memcpy(skb_put(nu->rx_skb, chunk_len), data, chunk_len);
+		data += chunk_len;
+		count -= chunk_len;
+
+		/* Chcek if packet is fully received */
+		if (nu->rx_packet_len == nu->rx_skb->len) {
+			/* Pass RX packet to driver */
+			if (nu->ops.recv(nu, nu->rx_skb) != 0)
+				nfc_err(nu->tty->dev, "corrupted RX packet\n");
+			/* Next packet will be a new one */
+			nu->rx_skb = NULL;
+		}
+	}
+
+	return 0;
+}
+
+/* -- Default recv handler -- */
+static int nci_uart_default_recv(struct nci_uart *nu, struct sk_buff *skb)
+{
+	return nci_recv_frame(nu->ndev, skb);
+}
+
+int nci_uart_register(struct nci_uart *nu)
+{
+	if (!nu || !nu->ops.open ||
+	    !nu->ops.recv || !nu->ops.close)
+		return -EINVAL;
+
+	/* Set the send callback */
+	nu->ops.send = nci_uart_send;
+
+	/* Install default handlers if not overridden */
+	if (!nu->ops.recv_buf)
+		nu->ops.recv_buf = nci_uart_default_recv_buf;
+	if (!nu->ops.recv)
+		nu->ops.recv = nci_uart_default_recv;
+
+	/* Add this driver in the driver list */
+	if (nci_uart_drivers[nu->driver]) {
+		pr_err("driver %d is already registered\n", nu->driver);
+		return -EBUSY;
+	}
+	nci_uart_drivers[nu->driver] = nu;
+
+	pr_info("NCI uart driver '%s [%d]' registered\n", nu->name, nu->driver);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(nci_uart_register);
+
+void nci_uart_unregister(struct nci_uart *nu)
+{
+	pr_info("NCI uart driver '%s [%d]' unregistered\n", nu->name,
+		nu->driver);
+
+	/* Remove this driver from the driver list */
+	nci_uart_drivers[nu->driver] = NULL;
+}
+EXPORT_SYMBOL_GPL(nci_uart_unregister);
+
+void nci_uart_set_config(struct nci_uart *nu, int baudrate, int flow_ctrl)
+{
+	struct ktermios new_termios;
+
+	if (!nu->tty)
+		return;
+
+#if LINUX_VERSION_IS_GEQ(3,12,0)
+	down_read(&nu->tty->termios_rwsem);
+#else
+	mutex_lock(&nu->tty->termios_mutex);
+#endif /* if LINUX_VERSION_IS_GEQ(3,12,0) */
+	new_termios = nu->tty->termios;
+#if LINUX_VERSION_IS_GEQ(3,12,0)
+	up_read(&nu->tty->termios_rwsem);
+#else
+	mutex_unlock(&nu->tty->termios_mutex);
+#endif /* if LINUX_VERSION_IS_GEQ(3,12,0) */
+	tty_termios_encode_baud_rate(&new_termios, baudrate, baudrate);
+
+	if (flow_ctrl)
+		new_termios.c_cflag |= CRTSCTS;
+	else
+		new_termios.c_cflag &= ~CRTSCTS;
+
+	tty_set_termios(nu->tty, &new_termios);
+}
+EXPORT_SYMBOL_GPL(nci_uart_set_config);
+
+static struct tty_ldisc_ops nci_uart_ldisc = {
+	.magic		= TTY_LDISC_MAGIC,
+	.owner		= THIS_MODULE,
+	.name		= "n_nci",
+	.open		= nci_uart_tty_open,
+	.close		= nci_uart_tty_close,
+	.read		= nci_uart_tty_read,
+	.write		= nci_uart_tty_write,
+	.poll		= nci_uart_tty_poll,
+	.receive_buf	= nci_uart_tty_receive,
+	.write_wakeup	= nci_uart_tty_wakeup,
+	.ioctl		= nci_uart_tty_ioctl,
+};
+
+static int __init nci_uart_init(void)
+{
+	memset(nci_uart_drivers, 0, sizeof(nci_uart_drivers));
+	return tty_register_ldisc(N_NCI, &nci_uart_ldisc);
+}
+
+static void __exit nci_uart_exit(void)
+{
+	tty_unregister_ldisc(N_NCI);
+}
+
+module_init(nci_uart_init);
+module_exit(nci_uart_exit);
+
+MODULE_AUTHOR("Marvell International Ltd.");
+MODULE_DESCRIPTION("NFC NCI UART driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_LDISC(N_NCI);