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>

5 files changed, 212 insertions, 1 deletions

diff --git a/drivers/pps/Makefile b/drivers/pps/Makefile
index 98960ddd3188..77c23457b739 100644
--- a/drivers/pps/Makefile
+++ b/drivers/pps/Makefile
@@ -3,6 +3,7 @@
 #
 
 pps_core-y                      := pps.o kapi.o sysfs.o
+pps_core-$(CONFIG_NTP_PPS)      += kc.o
 obj-$(CONFIG_PPS)               := pps_core.o
 obj-y                           += clients/
 
diff --git a/drivers/pps/kapi.c b/drivers/pps/kapi.c
index ebf33746c37c..cba1b43f7519 100644
--- a/drivers/pps/kapi.c
+++ b/drivers/pps/kapi.c
@@ -26,11 +26,14 @@
 #include <linux/init.h>
 #include <linux/sched.h>
 #include <linux/time.h>
+#include <linux/timex.h>
 #include <linux/spinlock.h>
 #include <linux/fs.h>
 #include <linux/pps_kernel.h>
 #include <linux/slab.h>
 
+#include "kc.h"
+
 /*
  * Local functions
  */
@@ -139,6 +142,7 @@ EXPORT_SYMBOL(pps_register_source);
 
 void pps_unregister_source(struct pps_device *pps)
 {
+        pps_kc_remove(pps);
         pps_unregister_cdev(pps);
 
         /* don't have to kfree(pps) here because it will be done on
@@ -211,6 +215,8 @@ void pps_event(struct pps_device *pps, struct pps_event_time *ts, int event,
                 captured = ~0;
         }
 
+        pps_kc_event(pps, ts, event);
+
         /* Wake up if captured something */
         if (captured) {
                 pps->last_ev++;
diff --git a/drivers/pps/kc.c b/drivers/pps/kc.c
new file mode 100644
index 000000000000..079e930b1938
--- /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);
+}
diff --git a/drivers/pps/kc.h b/drivers/pps/kc.h
new file mode 100644
index 000000000000..d296fcd0a175
--- /dev/null
+++ b/drivers/pps/kc.h
@@ -0,0 +1,46 @@
+/*
+ * PPS kernel consumer API header
+ *
+ * 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.
+ */
+
+#ifndef LINUX_PPS_KC_H
+#define LINUX_PPS_KC_H
+
+#include <linux/errno.h>
+#include <linux/pps_kernel.h>
+
+#ifdef CONFIG_NTP_PPS
+
+extern int pps_kc_bind(struct pps_device *pps,
+                struct pps_bind_args *bind_args);
+extern void pps_kc_remove(struct pps_device *pps);
+extern void pps_kc_event(struct pps_device *pps,
+                struct pps_event_time *ts, int event);
+
+
+#else /* CONFIG_NTP_PPS */
+
+static inline int pps_kc_bind(struct pps_device *pps,
+                struct pps_bind_args *bind_args) { return -EOPNOTSUPP; }
+static inline void pps_kc_remove(struct pps_device *pps) {}
+static inline void pps_kc_event(struct pps_device *pps,
+                struct pps_event_time *ts, int event) {}
+
+#endif /* CONFIG_NTP_PPS */
+
+#endif /* LINUX_PPS_KC_H */
diff --git a/drivers/pps/pps.c b/drivers/pps/pps.c
index 9e15cf1da946..2baadd21b7a6 100644
--- a/drivers/pps/pps.c
+++ b/drivers/pps/pps.c
@@ -33,6 +33,8 @@
 #include <linux/pps_kernel.h>
 #include <linux/slab.h>
 
+#include "kc.h"
+
 /*
  * Local variables
  */
@@ -198,9 +200,43 @@ static long pps_cdev_ioctl(struct file *file,
 
                 break;
         }
+        case PPS_KC_BIND: {
+                struct pps_bind_args bind_args;
+
+                dev_dbg(pps->dev, "PPS_KC_BIND\n");
+
+                /* Check the capabilities */
+                if (!capable(CAP_SYS_TIME))
+                        return -EPERM;
+
+                if (copy_from_user(&bind_args, uarg,
+                                        sizeof(struct pps_bind_args)))
+                        return -EFAULT;
+
+                /* Check for supported capabilities */
+                if ((bind_args.edge & ~pps->info.mode) != 0) {
+                        dev_err(pps->dev, "unsupported capabilities (%x)\n",
+                                        bind_args.edge);
+                        return -EINVAL;
+                }
+
+                /* Validate parameters roughly */
+                if (bind_args.tsformat != PPS_TSFMT_TSPEC ||
+                                (bind_args.edge & ~PPS_CAPTUREBOTH) != 0 ||
+                                bind_args.consumer != PPS_KC_HARDPPS) {
+                        dev_err(pps->dev, "invalid kernel consumer bind"
+                                        " parameters (%x)\n", bind_args.edge);
+                        return -EINVAL;
+                }
+
+                err = pps_kc_bind(pps, &bind_args);
+                if (err < 0)
+                        return err;
+
+                break;
+        }
         default:
                 return -ENOTTY;
-                break;
         }
 
         return 0;