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Diffstat (limited to 'drivers/pps/clients/pps_parport.c')
-rw-r--r--drivers/pps/clients/pps_parport.c225
1 files changed, 225 insertions, 0 deletions
diff --git a/drivers/pps/clients/pps_parport.c b/drivers/pps/clients/pps_parport.c
new file mode 100644
index 000000000..42f93d4c6
--- /dev/null
+++ b/drivers/pps/clients/pps_parport.c
@@ -0,0 +1,225 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * pps_parport.c -- kernel parallel port PPS client
+ *
+ * Copyright (C) 2009 Alexander Gordeev <lasaine@lvk.cs.msu.su>
+ */
+
+
+/*
+ * 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/slab.h>
+#include <linux/parport.h>
+#include <linux/pps_kernel.h>
+
+/* 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);
+
+static DEFINE_IDA(pps_client_index);
+
+/* 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 */
+ int index; /* device number */
+};
+
+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;
+}
+
+static void parport_attach(struct parport *port)
+{
+ struct pardev_cb pps_client_cb;
+ int index;
+ 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,
+ .owner = THIS_MODULE,
+ .dev = NULL
+ };
+
+ if (clear_wait > CLEAR_WAIT_MAX) {
+ pr_err("clear_wait value should be not greater then %d\n",
+ CLEAR_WAIT_MAX);
+ return;
+ }
+
+ device = kzalloc(sizeof(struct pps_client_pp), GFP_KERNEL);
+ if (!device) {
+ pr_err("memory allocation failed, not attaching\n");
+ return;
+ }
+
+ index = ida_simple_get(&pps_client_index, 0, 0, GFP_KERNEL);
+ memset(&pps_client_cb, 0, sizeof(pps_client_cb));
+ pps_client_cb.private = device;
+ pps_client_cb.irq_func = parport_irq;
+ pps_client_cb.flags = PARPORT_FLAG_EXCL;
+ device->pardev = parport_register_dev_model(port,
+ KBUILD_MODNAME,
+ &pps_client_cb,
+ index);
+ 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 (IS_ERR(device->pps)) {
+ pr_err("couldn't register PPS source\n");
+ goto err_release_dev;
+ }
+
+ device->cw = clear_wait;
+
+ port->ops->enable_irq(port);
+ device->index = index;
+
+ 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:
+ ida_simple_remove(&pps_client_index, index);
+ 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 (!pardev || 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);
+ ida_simple_remove(&pps_client_index, device->index);
+ kfree(device);
+}
+
+static struct parport_driver pps_parport_driver = {
+ .name = KBUILD_MODNAME,
+ .match_port = parport_attach,
+ .detach = parport_detach,
+ .devmodel = true,
+};
+module_parport_driver(pps_parport_driver);
+
+MODULE_AUTHOR("Alexander Gordeev <lasaine@lvk.cs.msu.su>");
+MODULE_DESCRIPTION("parallel port PPS client");
+MODULE_LICENSE("GPL");