diff options
Diffstat (limited to 'net/nfc/nci/uart.c')
| -rw-r--r-- | net/nfc/nci/uart.c | 495 |
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 000000000000..70c279543074 --- /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 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); |