For my modification of XFree86 keyboard event handling I need to detect *duration*
of key presses, i.e. difference in time between 2 input events.
Evdev, in current version, timestamps each event with do_gettimeofday(). In
presence of adjustements to timeofday the difference/duration information is
damaged.
I would like to read the events timestamped with
do_posix_clock_monotonic_gettime() time.
I have prepared a patch, which provides an IOCTL call with which a reader can
request this monotonic timestamp. The default behaviour remains unchanged (I
think useless).
What i am not sure about:
* evdev builds as module, so do_posix_clock_monotonic_gettime is needed
exported... so my patch adds
EXPORT_SYMBOL_GPL(do_posix_clock_monotonic_gettime) in kernel/posix-timers.c.
* _IOW macro to declare the ioctl number
I took just a successor of the highest pre-existant number.
* I don't know how interrupt handlers preempt one another. So, in my attempt to
attain the most precise timestamp, I would like the interrupt routine to ask
for the timestamp as soon as possible. I could prepare another patch, which
adds to each "struct input_dev" a slot where the timestamp is stored at the
beginning of the interrupt routine. Evdev then uses such timestamp, if the
lower-level driver provides it.
Signed-off-by: Michal Maruska <[email protected]>
--- linux-2.6.14-rc3.orig/drivers/input/evdev.c 2005-10-05 22:47:40.000000000 +0200
+++ linux-2.6.14-rc3.mmc/drivers/input/evdev.c 2005-10-06 14:27:16.084510018 +0200
@@ -38,6 +38,7 @@
struct input_event buffer[EVDEV_BUFFER_SIZE];
int head;
int tail;
+ int time_kind; /* which time to use for the timestamps. Monotonic or timeofday */
struct fasync_struct *fasync;
struct evdev *evdev;
struct list_head node;
@@ -45,15 +46,37 @@
static struct evdev *evdev_table[EVDEV_MINORS];
+static inline
+void
+mem_copy_time(struct timeval *a, struct timeval* b)
+{
+ memcpy(a, b, sizeof(struct timeval));
+}
+
static void evdev_event(struct input_handle *handle, unsigned int type, unsigned int code, int value)
{
struct evdev *evdev = handle->private;
struct evdev_list *list;
+ struct timeval mtv, dtv;
+ /* `do_posix_clock_monotonic_gettime' delivers a different struct,
+ * but i do the conversion immediately, and once. */
+ struct timespec mts;
+
+ do_posix_clock_monotonic_gettime(&mts);
+ mtv.tv_sec = mts.tv_sec;
+ mtv.tv_usec = mts.tv_nsec / 1000; /* should I >> 10 ? */
+
+ do_gettimeofday(&dtv); /* for backward compatibility: */
+
if (evdev->grab) {
list = evdev->grab;
- do_gettimeofday(&list->buffer[list->head].time);
+ if (list->time_kind == EV_USE_DAY_TIME)
+ mem_copy_time(&list->buffer[list->head].time,&dtv);
+ else
+ mem_copy_time(&list->buffer[list->head].time,&mtv);
+
list->buffer[list->head].type = type;
list->buffer[list->head].code = code;
list->buffer[list->head].value = value;
@@ -63,7 +86,11 @@
} else
list_for_each_entry(list, &evdev->list, node) {
- do_gettimeofday(&list->buffer[list->head].time);
+ if (list->time_kind == EV_USE_DAY_TIME)
+ mem_copy_time(&list->buffer[list->head].time,&dtv);
+ else
+ mem_copy_time(&list->buffer[list->head].time,&mtv);
+
list->buffer[list->head].type = type;
list->buffer[list->head].code = code;
list->buffer[list->head].value = value;
@@ -135,6 +162,7 @@
return -ENOMEM;
memset(list, 0, sizeof(struct evdev_list));
+ list->time_kind = EV_USE_DAY_TIME; /* for backward compatibility! */
list->evdev = evdev_table[i];
list_add_tail(&list->node, &evdev_table[i]->list);
file->private_data = list;
@@ -371,6 +399,17 @@
evdev->grab = NULL;
return 0;
}
+ case EVIOCTIME:
+ switch (arg) {
+ case EV_USE_MONOTONIC_TIME:
+ list->time_kind = EV_USE_MONOTONIC_TIME;
+ return 0;
+ case EV_USE_DAY_TIME:
+ list->time_kind = EV_USE_DAY_TIME;
+ return 0;
+ default:
+ return -EINVAL;
+ }
default:
--- linux-2.6.14-rc3.orig/include/linux/input.h 2005-10-05 23:07:39.833168000 +0200
+++ linux-2.6.14-rc3.mmc/include/linux/input.h 2005-10-05 22:47:40.000000000 +0200
@@ -78,6 +78,15 @@
#define EVIOCGRAB _IOW('E', 0x90, int) /* Grab/Release device */
+#define EVIOCTIME _IOW('E', 0x91, int) /* choose what kind of time to use for timestamps */
+
+/*
+ * Time used to timestamp
+ */
+#define EV_USE_MONOTONIC_TIME 0
+#define EV_USE_DAY_TIME 1
+
+
/*
* Event types
*/
--- linux-2.6.14-rc3/kernel/posix-timers.c 2005-10-05 23:07:40.295183000 +0200
+++ linux-2.6.14-rc3.mmc/kernel/posix-timers.c 2005-10-06 14:30:30.831829116 +0200
@@ -1223,6 +1223,7 @@
{
return do_posix_clock_monotonic_get(CLOCK_MONOTONIC, tp);
}
+EXPORT_SYMBOL_GPL(do_posix_clock_monotonic_gettime);
int do_posix_clock_nosettime(clockid_t clockid, struct timespec *tp)
{
-
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