--- /dev/null
+/*
+ * 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 and line discipline. */
+
+ /* FIXME: why is this needed. Note don't use ldisc_ref here as the
+ * open path is before the ldisc is referencable.
+ */
+
+ if (tty->ldisc->ops->flush_buffer)
+ tty->ldisc->ops->flush_buffer(tty);
+ 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;
+
+ down_read(&nu->tty->termios_rwsem);
+ new_termios = nu->tty->termios;
+ up_read(&nu->tty->termios_rwsem);
+ 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);
Code Review / kvmfornfv.git / blobdiff