pps: add kernel consumer support
Add an optional feature of PPSAPI, kernel consumer support, which uses the
added hardpps() function.
Signed-off-by: Alexander Gordeev <lasaine@lvk.cs.msu.su>
Acked-by: Rodolfo Giometti <giometti@linux.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/pps/kc.c b/drivers/pps/kc.c
new file mode 100644
index 0000000..079e930
--- /dev/null
+++ b/drivers/pps/kc.c
@@ -0,0 +1,122 @@
+/*
+ * PPS kernel consumer API
+ *
+ * Copyright (C) 2009-2010 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.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/init.h>
+#include <linux/spinlock.h>
+#include <linux/pps_kernel.h>
+
+#include "kc.h"
+
+/*
+ * Global variables
+ */
+
+/* state variables to bind kernel consumer */
+DEFINE_SPINLOCK(pps_kc_hardpps_lock);
+/* PPS API (RFC 2783): current source and mode for kernel consumer */
+struct pps_device *pps_kc_hardpps_dev; /* unique pointer to device */
+int pps_kc_hardpps_mode; /* mode bits for kernel consumer */
+
+/* pps_kc_bind - control PPS kernel consumer binding
+ * @pps: the PPS source
+ * @bind_args: kernel consumer bind parameters
+ *
+ * This function is used to bind or unbind PPS kernel consumer according to
+ * supplied parameters. Should not be called in interrupt context.
+ */
+int pps_kc_bind(struct pps_device *pps, struct pps_bind_args *bind_args)
+{
+ /* Check if another consumer is already bound */
+ spin_lock_irq(&pps_kc_hardpps_lock);
+
+ if (bind_args->edge == 0)
+ if (pps_kc_hardpps_dev == pps) {
+ pps_kc_hardpps_mode = 0;
+ pps_kc_hardpps_dev = NULL;
+ spin_unlock_irq(&pps_kc_hardpps_lock);
+ dev_info(pps->dev, "unbound kernel"
+ " consumer\n");
+ } else {
+ spin_unlock_irq(&pps_kc_hardpps_lock);
+ dev_err(pps->dev, "selected kernel consumer"
+ " is not bound\n");
+ return -EINVAL;
+ }
+ else
+ if (pps_kc_hardpps_dev == NULL ||
+ pps_kc_hardpps_dev == pps) {
+ pps_kc_hardpps_mode = bind_args->edge;
+ pps_kc_hardpps_dev = pps;
+ spin_unlock_irq(&pps_kc_hardpps_lock);
+ dev_info(pps->dev, "bound kernel consumer: "
+ "edge=0x%x\n", bind_args->edge);
+ } else {
+ spin_unlock_irq(&pps_kc_hardpps_lock);
+ dev_err(pps->dev, "another kernel consumer"
+ " is already bound\n");
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+/* pps_kc_remove - unbind kernel consumer on PPS source removal
+ * @pps: the PPS source
+ *
+ * This function is used to disable kernel consumer on PPS source removal
+ * if this source was bound to PPS kernel consumer. Can be called on any
+ * source safely. Should not be called in interrupt context.
+ */
+void pps_kc_remove(struct pps_device *pps)
+{
+ spin_lock_irq(&pps_kc_hardpps_lock);
+ if (pps == pps_kc_hardpps_dev) {
+ pps_kc_hardpps_mode = 0;
+ pps_kc_hardpps_dev = NULL;
+ spin_unlock_irq(&pps_kc_hardpps_lock);
+ dev_info(pps->dev, "unbound kernel consumer"
+ " on device removal\n");
+ } else
+ spin_unlock_irq(&pps_kc_hardpps_lock);
+}
+
+/* pps_kc_event - call hardpps() on PPS event
+ * @pps: the PPS source
+ * @ts: PPS event timestamp
+ * @event: PPS event edge
+ *
+ * This function calls hardpps() when an event from bound PPS source occurs.
+ */
+void pps_kc_event(struct pps_device *pps, struct pps_event_time *ts,
+ int event)
+{
+ unsigned long flags;
+
+ /* Pass some events to kernel consumer if activated */
+ spin_lock_irqsave(&pps_kc_hardpps_lock, flags);
+ if (pps == pps_kc_hardpps_dev && event & pps_kc_hardpps_mode)
+ hardpps(&ts->ts_real, &ts->ts_raw);
+ spin_unlock_irqrestore(&pps_kc_hardpps_lock, flags);
+}