Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755511Ab1BXSH3 (ORCPT ); Thu, 24 Feb 2011 13:07:29 -0500 Received: from mga02.intel.com ([134.134.136.20]:24267 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754465Ab1BXSHK (ORCPT ); Thu, 24 Feb 2011 13:07:10 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.62,219,1297065600"; d="scan'208";a="606213957" From: james_p_freyensee@linux.intel.com To: gregkh@suse.de Cc: linux-kernel@vger.kernel.org, suhail.ahmed@intel.com, james_p_freyensee@linux.intel.com, christophe.guerard@intel.com Subject: [PATCH 09/10] n_tracerouter ldisc driver. Date: Thu, 24 Feb 2011 10:07:03 -0800 Message-Id: <1298570824-26085-10-git-send-email-james_p_freyensee@linux.intel.com> X-Mailer: git-send-email 1.7.2.3 In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 8633 Lines: 283 From: J Freyensee This patch adds the n_tracerouter ldisc driver. It is part of the Intel-Atom PTI implementation solution. Signed-off-by: J Freyensee --- drivers/tty/n_tracerouter.c | 258 +++++++++++++++++++++++++++++++++++++++++++ 1 files changed, 258 insertions(+), 0 deletions(-) create mode 100644 drivers/tty/n_tracerouter.c diff --git a/drivers/tty/n_tracerouter.c b/drivers/tty/n_tracerouter.c new file mode 100644 index 0000000..d28dcb9 --- /dev/null +++ b/drivers/tty/n_tracerouter.c @@ -0,0 +1,258 @@ +/* + * 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 +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#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); + +/** + * tracerouter_alloc + * + * Allocates the structure needed for this ldisc. + */ +static struct tracerouter_data *tracerouter_alloc(void) +{ + struct tracerouter_data *tptr = kzalloc( + sizeof(struct tracerouter_data), + GFP_KERNEL); + if (tptr == NULL) + return NULL; + tptr->opencalled = 0; + return tptr; +} + +/** + * 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; + + WARN_ON(tptr->kref_tty != tr_data->kref_tty); + tty_driver_flush_buffer(tty); + mutex_lock(&routelock); + 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 = tracerouter_alloc(); + 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; + + kfree(tr_data); + retval = tty_unregister_ldisc(N_TRACEROUTER); + if (retval < 0) + pr_err("%s: Unregistration failed: %d\n", + __func__, retval); +} + +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"); -- 1.7.2.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/