Computes the device timestamp according to the specification.
It also ensures that if the time between two events is greater
than MAX_TIMESTAMP_INTERVAL, the timestamp will be reset.
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@xxxxxxxxx>
---
drivers/hid/hid-multitouch.c | 46 +++++++++++++++++++++++++++++++++++++++++---
include/linux/hid.h | 1 +
2 files changed, 44 insertions(+), 3 deletions(-)
diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c
index efae60c..47ccf3a 100644
--- a/drivers/hid/hid-multitouch.c
+++ b/drivers/hid/hid-multitouch.c
@@ -32,6 +32,7 @@
#include <linux/slab.h>
#include <linux/usb.h>
#include <linux/input/mt.h>
+#include <linux/jiffies.h>
#include "usbhid/usbhid.h"
@@ -98,6 +99,9 @@ struct mt_device {
bool serial_maybe; /* need to check for serial protocol */
bool curvalid; /* is the current contact valid? */
unsigned mt_flags; /* flags to pass to input-mt */
+ __s32 dev_time; /* the scan time provided by the device */
+ unsigned long jiffies; /* the frame's jiffies */
+ unsigned timestamp; /* the timestamp to be sent */
};
/* classes of device behavior */
@@ -126,6 +130,8 @@ struct mt_device {
#define MT_DEFAULT_MAXCONTACT 10
#define MT_MAX_MAXCONTACT 250
+#define MAX_TIMESTAMP_INTERVAL 500000
+
#define MT_USB_DEVICE(v, p) HID_DEVICE(BUS_USB, HID_GROUP_MULTITOUCH, v, p)
#define MT_BT_DEVICE(v, p) HID_DEVICE(BUS_BLUETOOTH, HID_GROUP_MULTITOUCH, v, p)
@@ -459,12 +465,19 @@ static int mt_input_mapping(struct hid_device *hdev, struct hid_input *hi,
mt_store_field(usage, td, hi);
td->last_field_index = field->index;
return 1;
+ case HID_DG_SCANTIME:
+ hid_map_usage(hi, usage, bit, max,
+ EV_MSC, MSC_TIMESTAMP);
+ set_bit(MSC_TIMESTAMP, hi->input->mscbit);
+ td->last_field_index = field->index;
+ return 1;
case HID_DG_CONTACTCOUNT:
td->last_field_index = field->index;
return 1;
case HID_DG_CONTACTMAX:
- /* we don't set td->last_slot_field as contactcount and
- * contact max are global to the report */
+ /* we don't set td->last_slot_field as scan time,
+ * contactcount and contact max are global to the
+ * report */
td->last_field_index = field->index;
return -1;
}
@@ -493,7 +506,8 @@ static int mt_input_mapped(struct hid_device *hdev, struct hid_input *hi,
struct hid_field *field, struct hid_usage *usage,
unsigned long **bit, int *max)
{
- if (usage->type == EV_KEY || usage->type == EV_ABS)
+ if (usage->type == EV_KEY || usage->type == EV_ABS ||
+ usage->type == EV_MSC)
set_bit(usage->type, hi->input->evbit);
return -1;
@@ -572,10 +586,33 @@ static void mt_complete_slot(struct mt_device *td, struct input_dev *input)
static void mt_sync_frame(struct mt_device *td, struct input_dev *input)
{
input_mt_sync_frame(input);
+ input_event(input, EV_MSC, MSC_TIMESTAMP, td->timestamp);
input_sync(input);
td->num_received = 0;
}
+static void mt_compute_timestamp(struct mt_device *td, struct hid_field *field,
+ __s32 value)
+{
+ long delta = value - td->dev_time;
+ unsigned long jdelta = jiffies_to_usecs(jiffies - td->jiffies);
+
+ td->jiffies = jiffies;
+ td->dev_time = value;
+
+ if (delta < 0)
+ delta += field->logical_maximum;
+
+ /* HID_DG_SCANTIME is expressed in 100us, we want it in ms. */
+ delta *= 100;
+
+ if (abs(delta - jdelta) > MAX_TIMESTAMP_INTERVAL)
+ /* obviously wrong clock -> the device time has been reset */
+ td->timestamp = 0;
+ else
+ td->timestamp += delta;
+}
+
static int mt_event(struct hid_device *hid, struct hid_field *field,
struct hid_usage *usage, __s32 value)
{
@@ -623,6 +660,9 @@ static int mt_event(struct hid_device *hid, struct hid_field *field,
case HID_DG_HEIGHT:
td->curdata.h = value;
break;
+ case HID_DG_SCANTIME:
+ mt_compute_timestamp(td, field, value);
+ break;
case HID_DG_CONTACTCOUNT:
/*
* Includes multi-packet support where subsequent
diff --git a/include/linux/hid.h b/include/linux/hid.h
index ce14c32..aaba0e7 100644
--- a/include/linux/hid.h
+++ b/include/linux/hid.h
@@ -279,6 +279,7 @@ struct hid_item {
#define HID_DG_DEVICEINDEX 0x000d0053
#define HID_DG_CONTACTCOUNT 0x000d0054
#define HID_DG_CONTACTMAX 0x000d0055
+#define HID_DG_SCANTIME 0x000d0056
/*
* HID report types --- Ouch! HID spec says 1 2 3!
--
1.8.0
--
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