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author | Linus Torvalds <torvalds@linux-foundation.org> | 2011-05-23 12:23:20 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2011-05-23 12:23:20 -0700 |
commit | 99dff5856220a02b8711f2e8746413ea6e53ccf6 (patch) | |
tree | d8bae7ccdf8f7ad5221b053bb74a6220df996b3a /drivers/tty/n_tracerouter.c | |
parent | bb74e8ca352eecefdc5c1a9ebab01f18aa2f6f3c (diff) | |
parent | d9a0fbfd7bc5d2c42f0fa9bcbdab62c4942d0388 (diff) | |
download | linux-99dff5856220a02b8711f2e8746413ea6e53ccf6.tar.bz2 |
Merge branch 'tty-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty-2.6
* 'tty-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty-2.6: (48 commits)
serial: 8250_pci: add support for Cronyx Omega PCI multiserial board.
tty/serial: Fix break handling for PORT_TEGRA
tty/serial: Add explicit PORT_TEGRA type
n_tracerouter and n_tracesink ldisc additions.
Intel PTI implementaiton of MIPI 1149.7.
Kernel documentation for the PTI feature.
export kernel call get_task_comm().
tty: Remove to support serial for S5P6442
pch_phub: Support new device ML7223
8250_pci: Add support for the Digi/IBM PCIe 2-port Adapter
ASoC: Update cx20442 for TTY API change
pch_uart: Support new device ML7223 IOH
parport: Use request_muxed_region for IT87 probe and lock
tty/serial: add support for Xilinx PS UART
n_gsm: Use print_hex_dump_bytes
drivers/tty/moxa.c: Put correct tty value
TTY: tty_io, annotate locking functions
TTY: serial_core, remove superfluous set_task_state
TTY: serial_core, remove invalid test
Char: moxa, fix locking in moxa_write
...
Fix up trivial conflicts in drivers/bluetooth/hci_ldisc.c and
drivers/tty/serial/Makefile.
I did the hci_ldisc thing as an evil merge, cleaning things up.
Diffstat (limited to 'drivers/tty/n_tracerouter.c')
-rw-r--r-- | drivers/tty/n_tracerouter.c | 243 |
1 files changed, 243 insertions, 0 deletions
diff --git a/drivers/tty/n_tracerouter.c b/drivers/tty/n_tracerouter.c new file mode 100644 index 000000000000..1f063d3aa32f --- /dev/null +++ b/drivers/tty/n_tracerouter.c @@ -0,0 +1,243 @@ +/* + * n_tracerouter.c - Trace data router through tty space + * + * Copyright (C) Intel 2011 + * + * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 + * as published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + * + * 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 <asm-generic/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"); |