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Message-Id: <20110419162015.e4446442.rdunlap@xenotime.net>
Date: Tue, 19 Apr 2011 16:20:15 -0700
From: Randy Dunlap <rdunlap@...otime.net>
To: james_p_freyensee@...ux.intel.com
Cc: gregkh@...e.de, linux-kernel@...r.kernel.org,
suhail.ahmed@...el.com, christophe.guerard@...el.com
Subject: Re: [PATCH 4/4] n_tracerouter and n_tracesink ldisc additions.
On Tue, 19 Apr 2011 15:58:09 -0700 james_p_freyensee@...ux.intel.com wrote:
> drivers/tty/Kconfig | 31 ++++++
> drivers/tty/Makefile | 2 +
> drivers/tty/n_tracerouter.c | 241 ++++++++++++++++++++++++++++++++++++++++++
> drivers/tty/n_tracesink.c | 244 +++++++++++++++++++++++++++++++++++++++++++
> drivers/tty/n_tracesink.h | 36 +++++++
> include/linux/tty.h | 2 +
> 6 files changed, 556 insertions(+), 0 deletions(-)
> create mode 100644 drivers/tty/n_tracerouter.c
> create mode 100644 drivers/tty/n_tracesink.c
> create mode 100644 drivers/tty/n_tracesink.h
>
> diff --git a/drivers/tty/Kconfig b/drivers/tty/Kconfig
> index 3fd7199..d1ab9c0 100644
> --- a/drivers/tty/Kconfig
> +++ b/drivers/tty/Kconfig
> @@ -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 Y
Don't add default Y misc drivers.
> + 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 Y
ditto.
> + 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".
> diff --git a/drivers/tty/n_tracerouter.c b/drivers/tty/n_tracerouter.c
> new file mode 100644
> index 0000000..7295799
> --- /dev/null
> +++ b/drivers/tty/n_tracerouter.c
> @@ -0,0 +1,241 @@
> +/*
> + * 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.
> + */
Fix multi-line comment style throughout.
> +#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);
> +/* 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
> +};
> diff --git a/drivers/tty/n_tracesink.c b/drivers/tty/n_tracesink.c
> new file mode 100644
> index 0000000..4c40127
> --- /dev/null
> +++ b/drivers/tty/n_tracesink.c
> @@ -0,0 +1,244 @@
> +/*
> + * 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.
> + */
Fix multi-line comment style throughout.
> +#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);
> +/* 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
> +};
---
~Randy
*** Remember to use Documentation/SubmitChecklist when testing your code ***
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