diff options
Diffstat (limited to 'drivers/tty/n_tracesink.c')
| -rw-r--r-- | drivers/tty/n_tracesink.c | 228 |
1 files changed, 0 insertions, 228 deletions
diff --git a/drivers/tty/n_tracesink.c b/drivers/tty/n_tracesink.c deleted file mode 100644 index d96ba82cc356..000000000000 --- a/drivers/tty/n_tracesink.c +++ /dev/null @@ -1,228 +0,0 @@ -// SPDX-License-Identifier: GPL-2.0 -/* - * n_tracesink.c - Trace data router and sink path through tty space. - * - * Copyright (C) Intel 2011 - * - * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - * - * The trace sink uses the Linux line discipline framework to receive - * trace data coming from the PTI source line discipline driver - * to a user-desired tty port, like USB. - * This is to provide a way to extract modem trace data on - * devices that do not have a PTI HW module, or just need modem - * trace data to come out of a different HW output port. - * 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/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_tracesink" - -/* - * there is a quirk with this ldisc is he can write data - * to a tty from anyone calling his kernel API, which - * meets customer requirements in the drivers/misc/pti.c - * project. So he needs to know when he can and cannot write when - * the API is called. In theory, the API can be called - * after an init() but before a successful open() which - * would crash the system if tty is not checked. - */ -static struct tty_struct *this_tty; -static DEFINE_MUTEX(writelock); - -/** - * n_tracesink_open() - Called when a tty is opened by a SW entity. - * @tty: terminal device to the ldisc. - * - * Return: - * 0 for success, - * -EFAULT = couldn't get a tty kref n_tracesink will sit - * on top of - * -EEXIST = open() called successfully once and it cannot - * be called again. - * - * Caveats: open() should only be successful the first time a - * SW entity calls it. - */ -static int n_tracesink_open(struct tty_struct *tty) -{ - int retval = -EEXIST; - - mutex_lock(&writelock); - if (this_tty == NULL) { - this_tty = tty_kref_get(tty); - if (this_tty == NULL) { - retval = -EFAULT; - } else { - tty->disc_data = this_tty; - tty_driver_flush_buffer(tty); - retval = 0; - } - } - mutex_unlock(&writelock); - - return retval; -} - -/** - * n_tracesink_close() - close connection - * @tty: terminal device to the ldisc. - * - * Called when a software entity wants to close a connection. - */ -static void n_tracesink_close(struct tty_struct *tty) -{ - mutex_lock(&writelock); - tty_driver_flush_buffer(tty); - tty_kref_put(this_tty); - this_tty = NULL; - tty->disc_data = NULL; - mutex_unlock(&writelock); -} - -/** - * n_tracesink_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_tracesink_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_tracesink_read(struct tty_struct *tty, struct file *file, - unsigned char __user *buf, size_t nr) { - return -EINVAL; -} - -/** - * n_tracesink_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_tracesink_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_tracesink_write(struct tty_struct *tty, struct file *file, - const unsigned char *buf, size_t nr) { - return -EINVAL; -} - -/** - * n_tracesink_datadrain() - Kernel API function used to route - * trace debugging data to user-defined - * port like USB. - * - * @buf: Trace debuging data buffer to write to tty target - * port. Null value will return with no write occurring. - * @count: Size of buf. Value of 0 or a negative number will - * return with no write occuring. - * - * Caveat: If this line discipline does not set the tty it sits - * on top of via an open() call, this API function will not - * call the tty's write() call because it will have no pointer - * to call the write(). - */ -void n_tracesink_datadrain(u8 *buf, int count) -{ - mutex_lock(&writelock); - - if ((buf != NULL) && (count > 0) && (this_tty != NULL)) - this_tty->ops->write(this_tty, buf, count); - - mutex_unlock(&writelock); -} -EXPORT_SYMBOL_GPL(n_tracesink_datadrain); - -/* - * 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. - */ - -/* - * tty_ldisc function operations for this driver. - */ -static struct tty_ldisc_ops tty_n_tracesink = { - .owner = THIS_MODULE, - .magic = TTY_LDISC_MAGIC, - .name = DRIVERNAME, - .open = n_tracesink_open, - .close = n_tracesink_close, - .read = n_tracesink_read, - .write = n_tracesink_write -}; - -/** - * n_tracesink_init- module initialisation - * - * Registers this module as a line discipline driver. - * - * Return: - * 0 for success, any other value error. - */ -static int __init n_tracesink_init(void) -{ - /* Note N_TRACESINK is defined in linux/tty.h */ - int retval = tty_register_ldisc(N_TRACESINK, &tty_n_tracesink); - - if (retval < 0) - pr_err("%s: Registration failed: %d\n", __func__, retval); - - return retval; -} - -/** - * n_tracesink_exit - module unload - * - * Removes this module as a line discipline driver. - */ -static void __exit n_tracesink_exit(void) -{ - int retval = tty_unregister_ldisc(N_TRACESINK); - - if (retval < 0) - pr_err("%s: Unregistration failed: %d\n", __func__, retval); -} - -module_init(n_tracesink_init); -module_exit(n_tracesink_exit); - -MODULE_LICENSE("GPL"); -MODULE_AUTHOR("Jay Freyensee"); -MODULE_ALIAS_LDISC(N_TRACESINK); -MODULE_DESCRIPTION("Trace sink ldisc driver"); |