diff options
Diffstat (limited to 'drivers/tty/n_tracerouter.c')
| -rw-r--r-- | drivers/tty/n_tracerouter.c | 233 |
1 files changed, 0 insertions, 233 deletions
diff --git a/drivers/tty/n_tracerouter.c b/drivers/tty/n_tracerouter.c deleted file mode 100644 index 4479af4d2fa5..000000000000 --- a/drivers/tty/n_tracerouter.c +++ /dev/null @@ -1,233 +0,0 @@ -// SPDX-License-Identifier: GPL-2.0 -/* - * n_tracerouter.c - Trace data router through tty space - * - * Copyright (C) Intel 2011 - * - * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - * - * This trace router uses the Linux line discipline framework to route - * trace data coming from a HW Modem to a PTI (Parallel Trace Module) port. - * The solution is not specific to a HW modem and this line disciple can - * be used to route any stream of data in kernel space. - * This is part of a solution for the P1149.7, compact JTAG, standard. - */ - -#include <linux/init.h> -#include <linux/kernel.h> -#include <linux/module.h> -#include <linux/types.h> -#include <linux/ioctl.h> -#include <linux/tty.h> -#include <linux/tty_ldisc.h> -#include <linux/errno.h> -#include <linux/string.h> -#include <linux/mutex.h> -#include <linux/slab.h> -#include <linux/bug.h> -#include "n_tracesink.h" - -/* - * Other ldisc drivers use 65536 which basically means, - * 'I can always accept 64k' and flow control is off. - * This number is deemed appropriate for this driver. - */ -#define RECEIVE_ROOM 65536 -#define DRIVERNAME "n_tracerouter" - -/* - * struct to hold private configuration data for this ldisc. - * opencalled is used to hold if this ldisc has been opened. - * kref_tty holds the tty reference the ldisc sits on top of. - */ -struct tracerouter_data { - u8 opencalled; - struct tty_struct *kref_tty; -}; -static struct tracerouter_data *tr_data; - -/* lock for when tty reference is being used */ -static DEFINE_MUTEX(routelock); - -/** - * n_tracerouter_open() - Called when a tty is opened by a SW entity. - * @tty: terminal device to the ldisc. - * - * Return: - * 0 for success. - * - * Caveats: This should only be opened one time per SW entity. - */ -static int n_tracerouter_open(struct tty_struct *tty) -{ - int retval = -EEXIST; - - mutex_lock(&routelock); - if (tr_data->opencalled == 0) { - - tr_data->kref_tty = tty_kref_get(tty); - if (tr_data->kref_tty == NULL) { - retval = -EFAULT; - } else { - tr_data->opencalled = 1; - tty->disc_data = tr_data; - tty->receive_room = RECEIVE_ROOM; - tty_driver_flush_buffer(tty); - retval = 0; - } - } - mutex_unlock(&routelock); - return retval; -} - -/** - * n_tracerouter_close() - close connection - * @tty: terminal device to the ldisc. - * - * Called when a software entity wants to close a connection. - */ -static void n_tracerouter_close(struct tty_struct *tty) -{ - struct tracerouter_data *tptr = tty->disc_data; - - mutex_lock(&routelock); - WARN_ON(tptr->kref_tty != tr_data->kref_tty); - tty_driver_flush_buffer(tty); - tty_kref_put(tr_data->kref_tty); - tr_data->kref_tty = NULL; - tr_data->opencalled = 0; - tty->disc_data = NULL; - mutex_unlock(&routelock); -} - -/** - * n_tracerouter_read() - read request from user space - * @tty: terminal device passed into the ldisc. - * @file: pointer to open file object. - * @buf: pointer to the data buffer that gets eventually returned. - * @nr: number of bytes of the data buffer that is returned. - * - * function that allows read() functionality in userspace. By default if this - * is not implemented it returns -EIO. This module is functioning like a - * router via n_tracerouter_receivebuf(), and there is no real requirement - * to implement this function. However, an error return value other than - * -EIO should be used just to show that there was an intent not to have - * this function implemented. Return value based on read() man pages. - * - * Return: - * -EINVAL - */ -static ssize_t n_tracerouter_read(struct tty_struct *tty, struct file *file, - unsigned char __user *buf, size_t nr) { - return -EINVAL; -} - -/** - * n_tracerouter_write() - Function that allows write() in userspace. - * @tty: terminal device passed into the ldisc. - * @file: pointer to open file object. - * @buf: pointer to the data buffer that gets eventually returned. - * @nr: number of bytes of the data buffer that is returned. - * - * By default if this is not implemented, it returns -EIO. - * This should not be implemented, ever, because - * 1. this driver is functioning like a router via - * n_tracerouter_receivebuf() - * 2. No writes to HW will ever go through this line discpline driver. - * However, an error return value other than -EIO should be used - * just to show that there was an intent not to have this function - * implemented. Return value based on write() man pages. - * - * Return: - * -EINVAL - */ -static ssize_t n_tracerouter_write(struct tty_struct *tty, struct file *file, - const unsigned char *buf, size_t nr) { - return -EINVAL; -} - -/** - * n_tracerouter_receivebuf() - Routing function for driver. - * @tty: terminal device passed into the ldisc. It's assumed - * tty will never be NULL. - * @cp: buffer, block of characters to be eventually read by - * someone, somewhere (user read() call or some kernel function). - * @fp: flag buffer. - * @count: number of characters (aka, bytes) in cp. - * - * This function takes the input buffer, cp, and passes it to - * an external API function for processing. - */ -static void n_tracerouter_receivebuf(struct tty_struct *tty, - const unsigned char *cp, - char *fp, int count) -{ - mutex_lock(&routelock); - n_tracesink_datadrain((u8 *) cp, count); - mutex_unlock(&routelock); -} - -/* - * Flush buffer is not impelemented as the ldisc has no internal buffering - * so the tty_driver_flush_buffer() is sufficient for this driver's needs. - */ - -static struct tty_ldisc_ops tty_ptirouter_ldisc = { - .owner = THIS_MODULE, - .magic = TTY_LDISC_MAGIC, - .name = DRIVERNAME, - .open = n_tracerouter_open, - .close = n_tracerouter_close, - .read = n_tracerouter_read, - .write = n_tracerouter_write, - .receive_buf = n_tracerouter_receivebuf -}; - -/** - * n_tracerouter_init - module initialisation - * - * Registers this module as a line discipline driver. - * - * Return: - * 0 for success, any other value error. - */ -static int __init n_tracerouter_init(void) -{ - int retval; - - tr_data = kzalloc(sizeof(struct tracerouter_data), GFP_KERNEL); - if (tr_data == NULL) - return -ENOMEM; - - - /* Note N_TRACEROUTER is defined in linux/tty.h */ - retval = tty_register_ldisc(N_TRACEROUTER, &tty_ptirouter_ldisc); - if (retval < 0) { - pr_err("%s: Registration failed: %d\n", __func__, retval); - kfree(tr_data); - } - return retval; -} - -/** - * n_tracerouter_exit - module unload - * - * Removes this module as a line discipline driver. - */ -static void __exit n_tracerouter_exit(void) -{ - int retval = tty_unregister_ldisc(N_TRACEROUTER); - - if (retval < 0) - pr_err("%s: Unregistration failed: %d\n", __func__, retval); - else - kfree(tr_data); -} - -module_init(n_tracerouter_init); -module_exit(n_tracerouter_exit); - -MODULE_LICENSE("GPL"); -MODULE_AUTHOR("Jay Freyensee"); -MODULE_ALIAS_LDISC(N_TRACEROUTER); -MODULE_DESCRIPTION("Trace router ldisc driver"); |