266 строки
6.5 KiB
C
266 строки
6.5 KiB
C
/*
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* pps_parport.c -- kernel parallel port PPS client
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*
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*
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* Copyright (C) 2009 Alexander Gordeev <lasaine@lvk.cs.msu.su>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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/*
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* TODO:
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* implement echo over SEL pin
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/irqnr.h>
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#include <linux/time.h>
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#include <linux/slab.h>
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#include <linux/parport.h>
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#include <linux/pps_kernel.h>
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#define DRVDESC "parallel port PPS client"
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/* module parameters */
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#define CLEAR_WAIT_MAX 100
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#define CLEAR_WAIT_MAX_ERRORS 5
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static unsigned int clear_wait = 100;
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MODULE_PARM_DESC(clear_wait,
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"Maximum number of port reads when polling for signal clear,"
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" zero turns clear edge capture off entirely");
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module_param(clear_wait, uint, 0);
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static DEFINE_IDA(pps_client_index);
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/* internal per port structure */
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struct pps_client_pp {
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struct pardevice *pardev; /* parport device */
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struct pps_device *pps; /* PPS device */
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unsigned int cw; /* port clear timeout */
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unsigned int cw_err; /* number of timeouts */
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int index; /* device number */
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};
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static inline int signal_is_set(struct parport *port)
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{
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return (port->ops->read_status(port) & PARPORT_STATUS_ACK) != 0;
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}
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/* parport interrupt handler */
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static void parport_irq(void *handle)
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{
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struct pps_event_time ts_assert, ts_clear;
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struct pps_client_pp *dev = handle;
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struct parport *port = dev->pardev->port;
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unsigned int i;
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unsigned long flags;
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/* first of all we get the time stamp... */
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pps_get_ts(&ts_assert);
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if (dev->cw == 0)
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/* clear edge capture disabled */
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goto out_assert;
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/* try capture the clear edge */
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/* We have to disable interrupts here. The idea is to prevent
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* other interrupts on the same processor to introduce random
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* lags while polling the port. Reading from IO port is known
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* to take approximately 1us while other interrupt handlers can
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* take much more potentially.
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*
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* Interrupts won't be disabled for a long time because the
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* number of polls is limited by clear_wait parameter which is
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* kept rather low. So it should never be an issue.
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*/
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local_irq_save(flags);
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/* check the signal (no signal means the pulse is lost this time) */
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if (!signal_is_set(port)) {
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local_irq_restore(flags);
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dev_err(dev->pps->dev, "lost the signal\n");
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goto out_assert;
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}
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/* poll the port until the signal is unset */
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for (i = dev->cw; i; i--)
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if (!signal_is_set(port)) {
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pps_get_ts(&ts_clear);
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local_irq_restore(flags);
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dev->cw_err = 0;
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goto out_both;
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}
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local_irq_restore(flags);
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/* timeout */
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dev->cw_err++;
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if (dev->cw_err >= CLEAR_WAIT_MAX_ERRORS) {
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dev_err(dev->pps->dev, "disabled clear edge capture after %d"
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" timeouts\n", dev->cw_err);
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dev->cw = 0;
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dev->cw_err = 0;
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}
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out_assert:
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/* fire assert event */
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pps_event(dev->pps, &ts_assert,
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PPS_CAPTUREASSERT, NULL);
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return;
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out_both:
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/* fire assert event */
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pps_event(dev->pps, &ts_assert,
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PPS_CAPTUREASSERT, NULL);
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/* fire clear event */
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pps_event(dev->pps, &ts_clear,
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PPS_CAPTURECLEAR, NULL);
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return;
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}
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static void parport_attach(struct parport *port)
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{
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struct pardev_cb pps_client_cb;
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int index;
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struct pps_client_pp *device;
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struct pps_source_info info = {
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.name = KBUILD_MODNAME,
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.path = "",
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.mode = PPS_CAPTUREBOTH | \
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PPS_OFFSETASSERT | PPS_OFFSETCLEAR | \
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PPS_ECHOASSERT | PPS_ECHOCLEAR | \
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PPS_CANWAIT | PPS_TSFMT_TSPEC,
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.owner = THIS_MODULE,
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.dev = NULL
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};
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device = kzalloc(sizeof(struct pps_client_pp), GFP_KERNEL);
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if (!device) {
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pr_err("memory allocation failed, not attaching\n");
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return;
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}
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index = ida_simple_get(&pps_client_index, 0, 0, GFP_KERNEL);
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memset(&pps_client_cb, 0, sizeof(pps_client_cb));
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pps_client_cb.private = device;
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pps_client_cb.irq_func = parport_irq;
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pps_client_cb.flags = PARPORT_FLAG_EXCL;
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device->pardev = parport_register_dev_model(port,
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KBUILD_MODNAME,
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&pps_client_cb,
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index);
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if (!device->pardev) {
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pr_err("couldn't register with %s\n", port->name);
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goto err_free;
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}
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if (parport_claim_or_block(device->pardev) < 0) {
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pr_err("couldn't claim %s\n", port->name);
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goto err_unregister_dev;
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}
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device->pps = pps_register_source(&info,
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PPS_CAPTUREBOTH | PPS_OFFSETASSERT | PPS_OFFSETCLEAR);
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if (IS_ERR(device->pps)) {
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pr_err("couldn't register PPS source\n");
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goto err_release_dev;
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}
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device->cw = clear_wait;
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port->ops->enable_irq(port);
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device->index = index;
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pr_info("attached to %s\n", port->name);
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return;
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err_release_dev:
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parport_release(device->pardev);
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err_unregister_dev:
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parport_unregister_device(device->pardev);
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err_free:
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ida_simple_remove(&pps_client_index, index);
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kfree(device);
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}
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static void parport_detach(struct parport *port)
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{
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struct pardevice *pardev = port->cad;
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struct pps_client_pp *device;
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/* FIXME: oooh, this is ugly! */
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if (!pardev || strcmp(pardev->name, KBUILD_MODNAME))
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/* not our port */
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return;
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device = pardev->private;
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port->ops->disable_irq(port);
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pps_unregister_source(device->pps);
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parport_release(pardev);
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parport_unregister_device(pardev);
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ida_simple_remove(&pps_client_index, device->index);
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kfree(device);
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}
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static struct parport_driver pps_parport_driver = {
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.name = KBUILD_MODNAME,
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.match_port = parport_attach,
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.detach = parport_detach,
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.devmodel = true,
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};
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/* module staff */
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static int __init pps_parport_init(void)
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{
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int ret;
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pr_info(DRVDESC "\n");
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if (clear_wait > CLEAR_WAIT_MAX) {
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pr_err("clear_wait value should be not greater"
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" then %d\n", CLEAR_WAIT_MAX);
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return -EINVAL;
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}
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ret = parport_register_driver(&pps_parport_driver);
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if (ret) {
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pr_err("unable to register with parport\n");
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return ret;
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}
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return 0;
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}
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static void __exit pps_parport_exit(void)
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{
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parport_unregister_driver(&pps_parport_driver);
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}
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module_init(pps_parport_init);
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module_exit(pps_parport_exit);
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MODULE_AUTHOR("Alexander Gordeev <lasaine@lvk.cs.msu.su>");
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MODULE_DESCRIPTION(DRVDESC);
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MODULE_LICENSE("GPL");
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