pps: add kernel consumer support

[pandora-kernel.git] / drivers / pps / kc.c

diff --git a/drivers/pps/kc.c b/drivers/pps/kc.c
new file mode 100644 (file)
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);
+}