/*
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* Copyright (C) 2015, Marvell International Ltd.
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*
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* This software file (the "File") is distributed by Marvell International
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* Ltd. under the terms of the GNU General Public License Version 2, June 1991
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* (the "License"). You may use, redistribute and/or modify this File in
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* accordance with the terms and conditions of the License, a copy of which
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* is available on the worldwide web at
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* http://www.gnu.org/licenses/old-licenses/gpl-2.0.txt.
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*
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* THE FILE IS DISTRIBUTED AS-IS, WITHOUT WARRANTY OF ANY KIND, AND THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE
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* ARE EXPRESSLY DISCLAIMED. The License provides additional details about
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* this warranty disclaimer.
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*/
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/* Inspired (hugely) by HCI LDISC implementation in Bluetooth.
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*
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* Copyright (C) 2000-2001 Qualcomm Incorporated
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* Copyright (C) 2002-2003 Maxim Krasnyansky <maxk@qualcomm.com>
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* Copyright (C) 2004-2005 Marcel Holtmann <marcel@holtmann.org>
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*/
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/init.h>
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#include <linux/types.h>
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#include <linux/fcntl.h>
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#include <linux/interrupt.h>
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#include <linux/ptrace.h>
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#include <linux/poll.h>
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#include <linux/slab.h>
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#include <linux/tty.h>
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#include <linux/errno.h>
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#include <linux/string.h>
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#include <linux/signal.h>
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#include <linux/ioctl.h>
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#include <linux/skbuff.h>
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#include <net/nfc/nci.h>
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#include <net/nfc/nci_core.h>
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/* TX states */
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#define NCI_UART_SENDING 1
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#define NCI_UART_TX_WAKEUP 2
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static struct nci_uart *nci_uart_drivers[NCI_UART_DRIVER_MAX];
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static inline struct sk_buff *nci_uart_dequeue(struct nci_uart *nu)
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{
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struct sk_buff *skb = nu->tx_skb;
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if (!skb)
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skb = skb_dequeue(&nu->tx_q);
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else
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nu->tx_skb = NULL;
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return skb;
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}
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static inline int nci_uart_queue_empty(struct nci_uart *nu)
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{
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if (nu->tx_skb)
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return 0;
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return skb_queue_empty(&nu->tx_q);
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}
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static int nci_uart_tx_wakeup(struct nci_uart *nu)
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{
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if (test_and_set_bit(NCI_UART_SENDING, &nu->tx_state)) {
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set_bit(NCI_UART_TX_WAKEUP, &nu->tx_state);
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return 0;
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}
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schedule_work(&nu->write_work);
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return 0;
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}
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static void nci_uart_write_work(struct work_struct *work)
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{
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struct nci_uart *nu = container_of(work, struct nci_uart, write_work);
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struct tty_struct *tty = nu->tty;
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struct sk_buff *skb;
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restart:
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clear_bit(NCI_UART_TX_WAKEUP, &nu->tx_state);
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if (nu->ops.tx_start)
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nu->ops.tx_start(nu);
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while ((skb = nci_uart_dequeue(nu))) {
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int len;
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set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
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len = tty->ops->write(tty, skb->data, skb->len);
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skb_pull(skb, len);
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if (skb->len) {
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nu->tx_skb = skb;
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break;
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}
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kfree_skb(skb);
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}
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if (test_bit(NCI_UART_TX_WAKEUP, &nu->tx_state))
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goto restart;
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if (nu->ops.tx_done && nci_uart_queue_empty(nu))
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nu->ops.tx_done(nu);
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clear_bit(NCI_UART_SENDING, &nu->tx_state);
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}
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static int nci_uart_set_driver(struct tty_struct *tty, unsigned int driver)
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{
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struct nci_uart *nu = NULL;
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int ret;
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if (driver >= NCI_UART_DRIVER_MAX)
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return -EINVAL;
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if (!nci_uart_drivers[driver])
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return -ENOENT;
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nu = kzalloc(sizeof(*nu), GFP_KERNEL);
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if (!nu)
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return -ENOMEM;
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memcpy(nu, nci_uart_drivers[driver], sizeof(struct nci_uart));
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nu->tty = tty;
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tty->disc_data = nu;
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skb_queue_head_init(&nu->tx_q);
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INIT_WORK(&nu->write_work, nci_uart_write_work);
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spin_lock_init(&nu->rx_lock);
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ret = nu->ops.open(nu);
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if (ret) {
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tty->disc_data = NULL;
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kfree(nu);
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} else if (!try_module_get(nu->owner)) {
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nu->ops.close(nu);
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tty->disc_data = NULL;
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kfree(nu);
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return -ENOENT;
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}
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return ret;
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}
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/* ------ LDISC part ------ */
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/* nci_uart_tty_open
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*
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* Called when line discipline changed to NCI_UART.
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*
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* Arguments:
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* tty pointer to tty info structure
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* Return Value:
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* 0 if success, otherwise error code
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*/
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static int nci_uart_tty_open(struct tty_struct *tty)
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{
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/* Error if the tty has no write op instead of leaving an exploitable
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* hole
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*/
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if (!tty->ops->write)
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return -EOPNOTSUPP;
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tty->disc_data = NULL;
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tty->receive_room = 65536;
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/* Flush any pending characters in the driver */
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tty_driver_flush_buffer(tty);
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return 0;
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}
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/* nci_uart_tty_close()
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*
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* Called when the line discipline is changed to something
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* else, the tty is closed, or the tty detects a hangup.
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*/
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static void nci_uart_tty_close(struct tty_struct *tty)
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{
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struct nci_uart *nu = (void *)tty->disc_data;
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/* Detach from the tty */
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tty->disc_data = NULL;
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if (!nu)
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return;
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kfree_skb(nu->tx_skb);
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kfree_skb(nu->rx_skb);
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skb_queue_purge(&nu->tx_q);
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nu->ops.close(nu);
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nu->tty = NULL;
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module_put(nu->owner);
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cancel_work_sync(&nu->write_work);
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kfree(nu);
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}
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/* nci_uart_tty_wakeup()
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*
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* Callback for transmit wakeup. Called when low level
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* device driver can accept more send data.
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*
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* Arguments: tty pointer to associated tty instance data
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* Return Value: None
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*/
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static void nci_uart_tty_wakeup(struct tty_struct *tty)
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{
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struct nci_uart *nu = (void *)tty->disc_data;
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if (!nu)
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return;
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clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
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if (tty != nu->tty)
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return;
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nci_uart_tx_wakeup(nu);
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}
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/* nci_uart_tty_receive()
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*
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* Called by tty low level driver when receive data is
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* available.
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*
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* Arguments: tty pointer to tty isntance data
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* data pointer to received data
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* flags pointer to flags for data
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* count count of received data in bytes
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*
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* Return Value: None
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*/
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static void nci_uart_tty_receive(struct tty_struct *tty, const u8 *data,
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char *flags, int count)
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{
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struct nci_uart *nu = (void *)tty->disc_data;
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if (!nu || tty != nu->tty)
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return;
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spin_lock(&nu->rx_lock);
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nu->ops.recv_buf(nu, (void *)data, flags, count);
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spin_unlock(&nu->rx_lock);
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tty_unthrottle(tty);
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}
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/* nci_uart_tty_ioctl()
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*
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* Process IOCTL system call for the tty device.
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*
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* Arguments:
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*
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* tty pointer to tty instance data
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* file pointer to open file object for device
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* cmd IOCTL command code
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* arg argument for IOCTL call (cmd dependent)
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*
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* Return Value: Command dependent
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*/
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static int nci_uart_tty_ioctl(struct tty_struct *tty, struct file *file,
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unsigned int cmd, unsigned long arg)
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{
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struct nci_uart *nu = (void *)tty->disc_data;
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int err = 0;
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switch (cmd) {
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case NCIUARTSETDRIVER:
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if (!nu)
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return nci_uart_set_driver(tty, (unsigned int)arg);
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else
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return -EBUSY;
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break;
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default:
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err = n_tty_ioctl_helper(tty, file, cmd, arg);
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break;
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}
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return err;
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}
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/* We don't provide read/write/poll interface for user space. */
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static ssize_t nci_uart_tty_read(struct tty_struct *tty, struct file *file,
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unsigned char *buf, size_t nr,
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void **cookie, unsigned long offset)
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{
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return 0;
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}
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static ssize_t nci_uart_tty_write(struct tty_struct *tty, struct file *file,
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const unsigned char *data, size_t count)
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{
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return 0;
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}
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static __poll_t nci_uart_tty_poll(struct tty_struct *tty,
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struct file *filp, poll_table *wait)
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{
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return 0;
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}
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static int nci_uart_send(struct nci_uart *nu, struct sk_buff *skb)
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{
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/* Queue TX packet */
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skb_queue_tail(&nu->tx_q, skb);
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/* Try to start TX (if possible) */
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nci_uart_tx_wakeup(nu);
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return 0;
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}
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/* -- Default recv_buf handler --
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*
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* This handler supposes that NCI frames are sent over UART link without any
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* framing. It reads NCI header, retrieve the packet size and once all packet
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* bytes are received it passes it to nci_uart driver for processing.
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*/
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static int nci_uart_default_recv_buf(struct nci_uart *nu, const u8 *data,
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char *flags, int count)
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{
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int chunk_len;
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if (!nu->ndev) {
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nfc_err(nu->tty->dev,
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"receive data from tty but no NCI dev is attached yet, drop buffer\n");
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return 0;
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}
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/* Decode all incoming data in packets
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* and enqueue then for processing.
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*/
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while (count > 0) {
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/* If this is the first data of a packet, allocate a buffer */
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if (!nu->rx_skb) {
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nu->rx_packet_len = -1;
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nu->rx_skb = nci_skb_alloc(nu->ndev,
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NCI_MAX_PACKET_SIZE,
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GFP_ATOMIC);
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if (!nu->rx_skb)
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return -ENOMEM;
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}
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/* Eat byte after byte till full packet header is received */
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if (nu->rx_skb->len < NCI_CTRL_HDR_SIZE) {
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skb_put_u8(nu->rx_skb, *data++);
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--count;
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continue;
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}
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/* Header was received but packet len was not read */
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if (nu->rx_packet_len < 0)
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nu->rx_packet_len = NCI_CTRL_HDR_SIZE +
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nci_plen(nu->rx_skb->data);
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/* Compute how many bytes are missing and how many bytes can
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* be consumed.
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*/
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chunk_len = nu->rx_packet_len - nu->rx_skb->len;
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if (count < chunk_len)
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chunk_len = count;
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skb_put_data(nu->rx_skb, data, chunk_len);
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data += chunk_len;
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count -= chunk_len;
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/* Chcek if packet is fully received */
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if (nu->rx_packet_len == nu->rx_skb->len) {
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/* Pass RX packet to driver */
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if (nu->ops.recv(nu, nu->rx_skb) != 0)
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nfc_err(nu->tty->dev, "corrupted RX packet\n");
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/* Next packet will be a new one */
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nu->rx_skb = NULL;
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}
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}
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return 0;
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}
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/* -- Default recv handler -- */
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static int nci_uart_default_recv(struct nci_uart *nu, struct sk_buff *skb)
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{
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return nci_recv_frame(nu->ndev, skb);
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}
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int nci_uart_register(struct nci_uart *nu)
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{
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if (!nu || !nu->ops.open ||
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!nu->ops.recv || !nu->ops.close)
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return -EINVAL;
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/* Set the send callback */
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nu->ops.send = nci_uart_send;
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/* Install default handlers if not overridden */
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if (!nu->ops.recv_buf)
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nu->ops.recv_buf = nci_uart_default_recv_buf;
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if (!nu->ops.recv)
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nu->ops.recv = nci_uart_default_recv;
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/* Add this driver in the driver list */
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if (nci_uart_drivers[nu->driver]) {
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pr_err("driver %d is already registered\n", nu->driver);
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return -EBUSY;
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}
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nci_uart_drivers[nu->driver] = nu;
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pr_info("NCI uart driver '%s [%d]' registered\n", nu->name, nu->driver);
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return 0;
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}
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EXPORT_SYMBOL_GPL(nci_uart_register);
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void nci_uart_unregister(struct nci_uart *nu)
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{
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pr_info("NCI uart driver '%s [%d]' unregistered\n", nu->name,
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nu->driver);
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/* Remove this driver from the driver list */
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nci_uart_drivers[nu->driver] = NULL;
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}
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EXPORT_SYMBOL_GPL(nci_uart_unregister);
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void nci_uart_set_config(struct nci_uart *nu, int baudrate, int flow_ctrl)
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{
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struct ktermios new_termios;
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if (!nu->tty)
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return;
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down_read(&nu->tty->termios_rwsem);
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new_termios = nu->tty->termios;
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up_read(&nu->tty->termios_rwsem);
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tty_termios_encode_baud_rate(&new_termios, baudrate, baudrate);
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if (flow_ctrl)
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new_termios.c_cflag |= CRTSCTS;
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else
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new_termios.c_cflag &= ~CRTSCTS;
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tty_set_termios(nu->tty, &new_termios);
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}
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EXPORT_SYMBOL_GPL(nci_uart_set_config);
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static struct tty_ldisc_ops nci_uart_ldisc = {
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.magic = TTY_LDISC_MAGIC,
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.owner = THIS_MODULE,
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.name = "n_nci",
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.open = nci_uart_tty_open,
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.close = nci_uart_tty_close,
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.read = nci_uart_tty_read,
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.write = nci_uart_tty_write,
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.poll = nci_uart_tty_poll,
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.receive_buf = nci_uart_tty_receive,
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.write_wakeup = nci_uart_tty_wakeup,
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.ioctl = nci_uart_tty_ioctl,
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.compat_ioctl = nci_uart_tty_ioctl,
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};
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static int __init nci_uart_init(void)
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{
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memset(nci_uart_drivers, 0, sizeof(nci_uart_drivers));
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return tty_register_ldisc(N_NCI, &nci_uart_ldisc);
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}
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static void __exit nci_uart_exit(void)
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{
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tty_unregister_ldisc(N_NCI);
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}
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module_init(nci_uart_init);
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module_exit(nci_uart_exit);
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MODULE_AUTHOR("Marvell International Ltd.");
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MODULE_DESCRIPTION("NFC NCI UART driver");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS_LDISC(N_NCI);
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