[PATCHv2 4/6] pps: add kernel consumer support

[Alexander Gordeev]

Add an optional feature of PPSAPI, kernel consumer support, which uses
the added hardpps() function.

Signed-off-by: Alexander Gordeev <lasaine@xxxxxxxxxxxxx>
---
 Documentation/ioctl/ioctl-number.txt |    2 +-
 drivers/pps/kapi.c                   |   26 +++++++++++++
 drivers/pps/pps.c                    |   67 +++++++++++++++++++++++++++++++++-
 include/linux/pps.h                  |    7 ++++
 include/linux/pps_kernel.h           |    6 +++
 5 files changed, 106 insertions(+), 2 deletions(-)

diff --git a/Documentation/ioctl/ioctl-number.txt b/Documentation/ioctl/ioctl-number.txt
index 9473749..d68718b 100644
--- a/Documentation/ioctl/ioctl-number.txt
+++ b/Documentation/ioctl/ioctl-number.txt
@@ -152,7 +152,7 @@ Code	Seq#	Include File		Comments
 'p'	40-7F	linux/nvram.h
 'p'	80-9F				user-space parport
 					<mailto:tim@xxxxxxxxxxxx>
-'p'	a1-a4	linux/pps.h		LinuxPPS
+'p'	a1-a5	linux/pps.h		LinuxPPS
 					<mailto:giometti@xxxxxxxx>
 'q'	00-1F	linux/serio.h
 'q'	80-FF				Internet PhoneJACK, Internet LineJACK
diff --git a/drivers/pps/kapi.c b/drivers/pps/kapi.c
index b87f699..5871744 100644
--- a/drivers/pps/kapi.c
+++ b/drivers/pps/kapi.c
@@ -25,6 +25,7 @@
 #include <linux/init.h>
 #include <linux/sched.h>
 #include <linux/time.h>
+#include <linux/timex.h>
 #include <linux/spinlock.h>
 #include <linux/idr.h>
 #include <linux/fs.h>
@@ -37,6 +38,12 @@
 DEFINE_SPINLOCK(pps_idr_lock);
 DEFINE_IDR(pps_idr);
 
+/* state variables to bind kernel consumer */
+/* PPS API (RFC 2783): current source and mode for ``kernel consumer'' */
+DEFINE_SPINLOCK(pps_kc_hardpps_lock);
+void	*pps_kc_hardpps_dev;	/* some unique pointer to device */
+int	pps_kc_hardpps_mode;	/* mode bits for kernel consumer */
+
 /*
  * Local functions
  */
@@ -248,6 +255,15 @@ void pps_unregister_source(int source)
 	}
 	spin_unlock_irq(&pps_idr_lock);
 
+	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);
+		pr_info("unbound kernel consumer on device removal\n");
+	} else
+		spin_unlock_irq(&pps_kc_hardpps_lock);
+
 	pps_unregister_cdev(pps);
 	pps_put_source(pps);
 }
@@ -325,6 +341,16 @@ void pps_event(int source, struct pps_event_time *ts, int event, void *data)
 
 		captured = ~0;
 	}
+	spin_lock(&pps_kc_hardpps_lock);
+	if (pps == pps_kc_hardpps_dev && event & pps_kc_hardpps_mode) {
+		struct timespec p_ts = {
+			.tv_sec = ts->ts_real.sec,
+			.tv_nsec = ts->ts_real.nsec
+		};
+
+		hardpps(&p_ts, &ts->ts_raw);
+	}
+	spin_unlock(&pps_kc_hardpps_lock);
 
 	/* Wake up iif captured somthing */
 	if (captured) {
diff --git a/drivers/pps/pps.c b/drivers/pps/pps.c
index ca5183b..22fdcfe 100644
--- a/drivers/pps/pps.c
+++ b/drivers/pps/pps.c
@@ -62,6 +62,8 @@ static long pps_cdev_ioctl(struct file *file,
 	struct pps_device *pps = file->private_data;
 	struct pps_kparams params;
 	struct pps_fdata fdata;
+	struct pps_bind_args bind_args;
+	unsigned long irq_flags;
 	unsigned long ticks;
 	void __user *uarg = (void __user *) arg;
 	int __user *iuarg = (int __user *) arg;
@@ -186,9 +188,72 @@ static long pps_cdev_ioctl(struct file *file,
 
 		break;
 
+	case PPS_KC_BIND:
+		pr_info("PPS_KC_BIND: source %d\n", pps->id);
+
+		/* 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) {
+			pr_err("PPS_KC_BIND: "
+					"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) {
+			pr_err("PPS_KC_BIND: "
+					"invalid kcbind parameters (%x)\n",
+					bind_args.edge);
+			return -EINVAL;
+		}
+
+		/* Check if another consumer is already bound */
+		spin_lock_irqsave(&pps_kc_hardpps_lock, irq_flags);
+
+		if (bind_args.edge == 0)
+			if (pps_kc_hardpps_dev == pps) {
+				pps_kc_hardpps_mode = 0;
+				pps_kc_hardpps_dev = NULL;
+				spin_unlock_irqrestore(&pps_kc_hardpps_lock,
+						irq_flags);
+				pr_info("unbound kernel consumer\n");
+			} else {
+				spin_unlock_irqrestore(&pps_kc_hardpps_lock,
+						irq_flags);
+				pr_err("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_irqrestore(&pps_kc_hardpps_lock,
+						irq_flags);
+				pr_info("bound kernel consumer: dev=%p, "
+					"edge=0x%x\n", pps, bind_args.edge);
+			} else {
+				spin_unlock_irqrestore(&pps_kc_hardpps_lock,
+						irq_flags);
+				pr_err("another kernel consumer"
+						" is already bound\n");
+				return -EINVAL;
+			}
+		break;
+
 	default:
 		return -ENOTTY;
-		break;
 	}
 
 	return 0;
diff --git a/include/linux/pps.h b/include/linux/pps.h
index 0194ab0..a9bb1d9 100644
--- a/include/linux/pps.h
+++ b/include/linux/pps.h
@@ -114,11 +114,18 @@ struct pps_fdata {
 	struct pps_ktime timeout;
 };
 
+struct pps_bind_args {
+	int tsformat;	/* format of time stamps */
+	int edge;	/* selected event type */
+	int consumer;	/* selected kernel consumer */
+};
+
 #include <linux/ioctl.h>
 
 #define PPS_GETPARAMS		_IOR('p', 0xa1, struct pps_kparams *)
 #define PPS_SETPARAMS		_IOW('p', 0xa2, struct pps_kparams *)
 #define PPS_GETCAP		_IOR('p', 0xa3, int *)
 #define PPS_FETCH		_IOWR('p', 0xa4, struct pps_fdata *)
+#define PPS_KC_BIND		_IOW('p', 0xa5, struct pps_bind_args *)
 
 #endif /* _PPS_H_ */
diff --git a/include/linux/pps_kernel.h b/include/linux/pps_kernel.h
index 9bda892..2b203cd 100644
--- a/include/linux/pps_kernel.h
+++ b/include/linux/pps_kernel.h
@@ -80,6 +80,12 @@ extern struct timespec pps_irq_ts[];
 
 extern struct device_attribute pps_attrs[];
 
+/* state variables to bind kernel consumer */
+/* PPS API (RFC 2783): current source and mode for ``kernel consumer'' */
+extern spinlock_t pps_kc_hardpps_lock;
+extern void *pps_kc_hardpps_dev;	/* some unique pointer to device */
+extern int pps_kc_hardpps_mode;		/* mode bits for kernel consumer */
+
 /*
  * Exported functions
  */
-- 
1.6.6.1

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