[LinuxPPS] [PATCH 1/3] pps: add kernel consumer support
Alexander Gordeev
lasaine at lvk.cs.msu.su
Thu Oct 1 22:37:01 CEST 2009
Add an optional feature of PPSAPI, kernel consumer support, with a stub
hardpps function.
Signed-off-by: Alexander Gordeev <lasaine at lvk.cs.msu.su>
---
Documentation/ioctl/ioctl-number.txt | 2 +-
Documentation/pps/timepps.h | 10 ++++--
drivers/pps/kapi.c | 37 +++++++++++++++++++++
drivers/pps/pps.c | 60 +++++++++++++++++++++++++++++++++-
include/linux/pps.h | 13 +++++++
5 files changed, 117 insertions(+), 5 deletions(-)
diff --git a/Documentation/ioctl/ioctl-number.txt b/Documentation/ioctl/ioctl-number.txt
index df7aeca..eda1e93 100644
--- a/Documentation/ioctl/ioctl-number.txt
+++ b/Documentation/ioctl/ioctl-number.txt
@@ -151,7 +151,7 @@ Code Seq# Include File Comments
'p' 40-7F linux/nvram.h
'p' 80-9F user-space parport
<mailto:tim at cyberelk.net>
-'p' a1-a4 linux/pps.h LinuxPPS
+'p' a1-a5 linux/pps.h LinuxPPS
<mailto:giometti at linux.it>
'q' 00-1F linux/serio.h
'q' 80-FF Internet PhoneJACK, Internet LineJACK
diff --git a/Documentation/pps/timepps.h b/Documentation/pps/timepps.h
index d2628d2..84e5544 100644
--- a/Documentation/pps/timepps.h
+++ b/Documentation/pps/timepps.h
@@ -190,9 +190,13 @@ static __inline int time_pps_kcbind(pps_handle_t handle,
const int kernel_consumer,
const int edge, const int tsformat)
{
- /* LinuxPPS doesn't implement kernel consumer feature */
- errno = EOPNOTSUPP;
- return -1;
+ struct pps_bind_args __bind_args;
+
+ __bind_args.tsformat = tsformat;
+ __bind_args.edge = edge;
+ __bind_args.consumer = kernel_consumer;
+
+ return ioctl(handle, PPS_KC_BIND, &__bind_args);
}
#endif /* _SYS_TIMEPPS_H_ */
diff --git a/drivers/pps/kapi.c b/drivers/pps/kapi.c
index e0b75ed..edb5315 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 = NULL; /* some unique pointer to device */
+int pps_kc_hardpps_mode = 0; /* mode bits for kernel consumer */
+
/*
* Local functions
*/
@@ -253,6 +260,30 @@ void pps_unregister_source(int source)
}
EXPORT_SYMBOL(pps_unregister_source);
+/*
+ * hardpps() - discipline CPU clock oscillator to external PPS signal
+ *
+ * This routine is called at each PPS interrupt in order to discipline
+ * the CPU clock oscillator to the PPS signal. There are two independent
+ * first-order feedback loops, one for the phase, the other for the
+ * frequency. The phase loop measures and grooms the PPS phase offset
+ * and leaves it in a handy spot for the seconds overflow routine. The
+ * frequency loop averages successive PPS phase differences and
+ * calculates the PPS frequency offset, which is also processed by the
+ * seconds overflow routine. The code requires the caller to capture the
+ * time and architecture-dependent hardware counter values in
+ * nanoseconds at the on-time PPS signal transition.
+ *
+ * Note that, on some Unix systems this routine runs at an interrupt
+ * priority level higher than the timer interrupt routine second_overflow().
+ * Therefore, the variables used are distinct from the second_overflow()
+ * variables, except for the actual time and frequency variables, which
+ * are determined by this routine and updated atomically.
+ */
+void hardpps(const struct timespec *p_ts, long nsec)
+{
+}
+
/* pps_event - register a PPS event into the system
* @source: the PPS source ID
* @ts: the event timestamp
@@ -315,6 +346,12 @@ void pps_event(int source, struct pps_ktime *ts, int event, void *data)
pr_debug("capture clear seq #%u for source %d\n",
pps->clear_sequence, source);
}
+ spin_lock(&pps_kc_hardpps_lock);
+ if (pps == pps_kc_hardpps_dev && event & pps_kc_hardpps_mode) {
+ struct timespec p_ts = { .tv_sec = ts->sec, .tv_nsec = ts->nsec };
+ hardpps(&p_ts, 0);
+ }
+ spin_unlock(&pps_kc_hardpps_lock);
pps->go = ~0;
wake_up_interruptible(&pps->queue);
diff --git a/drivers/pps/pps.c b/drivers/pps/pps.c
index 23ea070..4404763 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;
@@ -181,9 +183,65 @@ 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 8a92204..558d679 100644
--- a/include/linux/pps.h
+++ b/include/linux/pps.h
@@ -113,12 +113,19 @@ 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 *)
#ifdef __KERNEL__
@@ -177,6 +184,12 @@ 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
*/
--
1.6.3.3
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