pps: add parallel port PPS client (a10203c6) · Commits · 戴 / test

drivers/pps/clients/Kconfig

+7 −0

Original line number	Diff line number	Diff line
		@@ -22,4 +22,11 @@ config PPS_CLIENT_LDISC
		If you say yes here you get support for a PPS source connected
		with the CD (Carrier Detect) pin of your serial port.

		config PPS_CLIENT_PARPORT
		tristate "Parallel port PPS client"
		depends on PPS && PARPORT
		help
		If you say yes here you get support for a PPS source connected
		with the interrupt pin of your parallel port.

		endif

drivers/pps/clients/Makefile

+1 −0

Original line number	Diff line number	Diff line
		@@ -4,6 +4,7 @@

		obj-$(CONFIG_PPS_CLIENT_KTIMER) += pps-ktimer.o
		obj-$(CONFIG_PPS_CLIENT_LDISC) += pps-ldisc.o
		obj-$(CONFIG_PPS_CLIENT_PARPORT) += pps_parport.o

		ifeq ($(CONFIG_PPS_DEBUG),y)
		EXTRA_CFLAGS += -DDEBUG

drivers/pps/clients/pps_parport.c

0 → 100644

+258 −0

Original line number	Diff line number	Diff line
		/*
		* pps_parport.c -- kernel parallel port PPS client
		*
		*
		* Copyright (C) 2009 Alexander Gordeev <lasaine@lvk.cs.msu.su>
		*
		* This program is free software; you can redistribute it and/or modify
		* it under the terms of the GNU General Public License as published by
		* the Free Software Foundation; either version 2 of the License, or
		* (at your option) any later version.
		*
		* 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.
		*
		* You should have received a copy of the GNU General Public License
		* along with this program; if not, write to the Free Software
		* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
		*/


		/*
		* TODO:
		* implement echo over SEL pin
		*/

		#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

		#include <linux/kernel.h>
		#include <linux/module.h>
		#include <linux/init.h>
		#include <linux/irqnr.h>
		#include <linux/time.h>
		#include <linux/parport.h>
		#include <linux/pps_kernel.h>

		#define DRVDESC "parallel port PPS client"

		/* module parameters */

		#define CLEAR_WAIT_MAX 100
		#define CLEAR_WAIT_MAX_ERRORS 5

		static unsigned int clear_wait = 100;
		MODULE_PARM_DESC(clear_wait,
		"Maximum number of port reads when polling for signal clear,"
		" zero turns clear edge capture off entirely");
		module_param(clear_wait, uint, 0);


		/* internal per port structure */
		struct pps_client_pp {
		struct pardevice pardev; / parport device */
		struct pps_device pps; / PPS device */
		unsigned int cw; /* port clear timeout */
		unsigned int cw_err; /* number of timeouts */
		};

		static inline int signal_is_set(struct parport *port)
		{
		return (port->ops->read_status(port) & PARPORT_STATUS_ACK) != 0;
		}

		/* parport interrupt handler */
		static void parport_irq(void *handle)
		{
		struct pps_event_time ts_assert, ts_clear;
		struct pps_client_pp *dev = handle;
		struct parport *port = dev->pardev->port;
		unsigned int i;
		unsigned long flags;

		/* first of all we get the time stamp... */
		pps_get_ts(&ts_assert);

		if (dev->cw == 0)
		/* clear edge capture disabled */
		goto out_assert;

		/* try capture the clear edge */

		/* We have to disable interrupts here. The idea is to prevent
		* other interrupts on the same processor to introduce random
		* lags while polling the port. Reading from IO port is known
		* to take approximately 1us while other interrupt handlers can
		* take much more potentially.
		*
		* Interrupts won't be disabled for a long time because the
		* number of polls is limited by clear_wait parameter which is
		* kept rather low. So it should never be an issue.
		*/
		local_irq_save(flags);
		/* check the signal (no signal means the pulse is lost this time) */
		if (!signal_is_set(port)) {
		local_irq_restore(flags);
		dev_err(dev->pps->dev, "lost the signal\n");
		goto out_assert;
		}

		/* poll the port until the signal is unset */
		for (i = dev->cw; i; i--)
		if (!signal_is_set(port)) {
		pps_get_ts(&ts_clear);
		local_irq_restore(flags);
		dev->cw_err = 0;
		goto out_both;
		}
		local_irq_restore(flags);

		/* timeout */
		dev->cw_err++;
		if (dev->cw_err >= CLEAR_WAIT_MAX_ERRORS) {
		dev_err(dev->pps->dev, "disabled clear edge capture after %d"
		" timeouts\n", dev->cw_err);
		dev->cw = 0;
		dev->cw_err = 0;
		}

		out_assert:
		/* fire assert event */
		pps_event(dev->pps, &ts_assert,
		PPS_CAPTUREASSERT, NULL);
		return;

		out_both:
		/* fire assert event */
		pps_event(dev->pps, &ts_assert,
		PPS_CAPTUREASSERT, NULL);
		/* fire clear event */
		pps_event(dev->pps, &ts_clear,
		PPS_CAPTURECLEAR, NULL);
		return;
		}

		/* the PPS echo function */
		static void pps_echo(struct pps_device pps, int event, void data)
		{
		dev_info(pps->dev, "echo %s %s\n",
		event & PPS_CAPTUREASSERT ? "assert" : "",
		event & PPS_CAPTURECLEAR ? "clear" : "");
		}

		static void parport_attach(struct parport *port)
		{
		struct pps_client_pp *device;
		struct pps_source_info info = {
		.name = KBUILD_MODNAME,
		.path = "",
		.mode = PPS_CAPTUREBOTH \| \
		PPS_OFFSETASSERT \| PPS_OFFSETCLEAR \| \
		PPS_ECHOASSERT \| PPS_ECHOCLEAR \| \
		PPS_CANWAIT \| PPS_TSFMT_TSPEC,
		.echo = pps_echo,
		.owner = THIS_MODULE,
		.dev = NULL
		};

		device = kzalloc(sizeof(struct pps_client_pp), GFP_KERNEL);
		if (!device) {
		pr_err("memory allocation failed, not attaching\n");
		return;
		}

		device->pardev = parport_register_device(port, KBUILD_MODNAME,
		NULL, NULL, parport_irq, 0, device);
		if (!device->pardev) {
		pr_err("couldn't register with %s\n", port->name);
		goto err_free;
		}

		if (parport_claim_or_block(device->pardev) < 0) {
		pr_err("couldn't claim %s\n", port->name);
		goto err_unregister_dev;
		}

		device->pps = pps_register_source(&info,
		PPS_CAPTUREBOTH \| PPS_OFFSETASSERT \| PPS_OFFSETCLEAR);
		if (device->pps == NULL) {
		pr_err("couldn't register PPS source\n");
		goto err_release_dev;
		}

		device->cw = clear_wait;

		port->ops->enable_irq(port);

		pr_info("attached to %s\n", port->name);

		return;

		err_release_dev:
		parport_release(device->pardev);
		err_unregister_dev:
		parport_unregister_device(device->pardev);
		err_free:
		kfree(device);
		}

		static void parport_detach(struct parport *port)
		{
		struct pardevice *pardev = port->cad;
		struct pps_client_pp *device;

		/* FIXME: oooh, this is ugly! */
		if (strcmp(pardev->name, KBUILD_MODNAME))
		/* not our port */
		return;

		device = pardev->private;

		port->ops->disable_irq(port);
		pps_unregister_source(device->pps);
		parport_release(pardev);
		parport_unregister_device(pardev);
		kfree(device);
		}

		static struct parport_driver pps_parport_driver = {
		.name = KBUILD_MODNAME,
		.attach = parport_attach,
		.detach = parport_detach,
		};

		/* module staff */

		static int __init pps_parport_init(void)
		{
		int ret;

		pr_info(DRVDESC "\n");

		if (clear_wait > CLEAR_WAIT_MAX) {
		pr_err("clear_wait value should be not greater"
		" then %d\n", CLEAR_WAIT_MAX);
		return -EINVAL;
		}

		ret = parport_register_driver(&pps_parport_driver);
		if (ret) {
		pr_err("unable to register with parport\n");
		return ret;
		}

		return 0;
		}

		static void __exit pps_parport_exit(void)
		{
		parport_unregister_driver(&pps_parport_driver);
		}

		module_init(pps_parport_init);
		module_exit(pps_parport_exit);

		MODULE_AUTHOR("Alexander Gordeev <lasaine@lvk.cs.msu.su>");
		MODULE_DESCRIPTION(DRVDESC);
		MODULE_LICENSE("GPL");

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