n_tracerouter and n_tracesink ldisc additions. (ee4f6b4b) · Commits · e / devices / android_kernel_sony_msm8998

drivers/tty/Kconfig

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Original line number	Diff line number	Diff line
		@@ -319,3 +319,34 @@ config N_GSM
		This line discipline provides support for the GSM MUX protocol and
		presents the mux as a set of 61 individual tty devices.

		config TRACE_ROUTER
		tristate "Trace data router for MIPI P1149.7 cJTAG standard"
		depends on TRACE_SINK
		default n
		help
		The trace router uses the Linux tty line discipline framework to
		route trace data coming from a tty port (say UART for example) to
		the trace sink line discipline driver and to another tty port (say
		USB). This is part of a solution for the MIPI P1149.7, compact JTAG,
		standard, which is for debugging mobile devices. The PTI driver in
		drivers/misc/pti.c defines the majority of this MIPI solution.

		You should select this driver if the target kernel is meant for
		a mobile device containing a modem. Then you will need to select
		"Trace data sink for MIPI P1149.7 cJTAG standard" line discipline
		driver.

		config TRACE_SINK
		tristate "Trace data sink for MIPI P1149.7 cJTAG standard"
		default n
		help
		The trace sink uses the Linux line discipline framework to receive
		trace data coming from the trace router line discipline driver
		to a user-defined tty port target, 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.

		If you select this option, you need to select
		"Trace data router for MIPI P1149.7 cJTAG standard".

drivers/tty/Makefile

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Original line number	Diff line number	Diff line
		@@ -6,6 +6,8 @@ obj-$(CONFIG_AUDIT) += tty_audit.o
		obj-$(CONFIG_MAGIC_SYSRQ) += sysrq.o
		obj-$(CONFIG_N_HDLC) += n_hdlc.o
		obj-$(CONFIG_N_GSM) += n_gsm.o
		obj-$(CONFIG_TRACE_ROUTER) += n_tracerouter.o
		obj-$(CONFIG_TRACE_SINK) += n_tracesink.o
		obj-$(CONFIG_R3964) += n_r3964.o

		obj-y += vt/

drivers/tty/n_tracerouter.c

0 → 100644

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		/*
		* 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");

drivers/tty/n_tracesink.c

0 → 100644

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		/*
		* n_tracesink.c - Trace data router and sink path 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.
		*
		* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
		*
		* 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 <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_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");

drivers/tty/n_tracesink.h

0 → 100644

+36 −0

Original line number	Diff line number	Diff line
		/*
		* n_tracesink.h - Kernel driver API to route trace data in kernel 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.
		*
		* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
		*
		* The PTI (Parallel Trace Interface) driver directs trace data routed from
		* various parts in the system out through the Intel Penwell PTI port and
		* out of the mobile device for analysis with a debugging tool
		* (Lauterbach, Fido). This is part of a solution for the MIPI P1149.7,
		* compact JTAG, standard.
		*
		* This header file is used by n_tracerouter to be able to send the
		* data of it's tty port to the tty port this module sits. This
		* mechanism can also be used independent of the PTI module.
		*
		*/

		#ifndef N_TRACESINK_H_
		#define N_TRACESINK_H_

		void n_tracesink_datadrain(u8 *buf, int count);

		#endif