/* * 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; 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);