3 files changed, 266 insertions, 0 deletions

diff --git a/drivers/pps/clients/Kconfig b/drivers/pps/clients/Kconfig
index 4e801bd7254f..8520a7f4dd62 100644
--- a/drivers/pps/clients/Kconfig
+++ b/drivers/pps/clients/Kconfig
@@ -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
diff --git a/drivers/pps/clients/Makefile b/drivers/pps/clients/Makefile
index 812c9b19b430..42517da07049 100644
--- a/drivers/pps/clients/Makefile
+++ b/drivers/pps/clients/Makefile
@@ -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
diff --git a/drivers/pps/clients/pps_parport.c b/drivers/pps/clients/pps_parport.c
new file mode 100644
index 000000000000..32221efd9ca9
--- /dev/null
+++ b/drivers/pps/clients/pps_parport.c
@@ -0,0 +1,258 @@
+/*
+ * 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");