From patchwork Fri Jan 6 02:50:12 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: John Stultz X-Patchwork-Id: 6075 Return-Path: X-Original-To: patchwork@peony.canonical.com Delivered-To: patchwork@peony.canonical.com Received: from fiordland.canonical.com (fiordland.canonical.com [91.189.94.145]) by peony.canonical.com (Postfix) with ESMTP id CC89C23E10 for ; Fri, 6 Jan 2012 02:50:30 +0000 (UTC) Received: from mail-ey0-f180.google.com (mail-ey0-f180.google.com [209.85.215.180]) by fiordland.canonical.com (Postfix) with ESMTP id AF022A183D0 for ; Fri, 6 Jan 2012 02:50:30 +0000 (UTC) Received: by eaac11 with SMTP id c11so1071450eaa.11 for ; Thu, 05 Jan 2012 18:50:30 -0800 (PST) Received: by 10.205.141.78 with SMTP id jd14mr1842304bkc.107.1325818230376; Thu, 05 Jan 2012 18:50:30 -0800 (PST) X-Forwarded-To: linaro-patchwork@canonical.com X-Forwarded-For: patch@linaro.org linaro-patchwork@canonical.com Delivered-To: patches@linaro.org Received: by 10.205.82.144 with SMTP id ac16cs418100bkc; Thu, 5 Jan 2012 18:50:30 -0800 (PST) Received: by 10.68.73.100 with SMTP id k4mr11233079pbv.55.1325818227702; Thu, 05 Jan 2012 18:50:27 -0800 (PST) Received: from e5.ny.us.ibm.com (e5.ny.us.ibm.com. 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Violators will be prosecuted; Thu, 5 Jan 2012 21:50:23 -0500 Received: from d01av03.pok.ibm.com (d01av03.pok.ibm.com [9.56.224.217]) by d01relay05.pok.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id q062oMaV260536; Thu, 5 Jan 2012 21:50:22 -0500 Received: from d01av03.pok.ibm.com (loopback [127.0.0.1]) by d01av03.pok.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id q062oLJQ029857; Fri, 6 Jan 2012 00:50:22 -0200 Received: from kernel.beaverton.ibm.com (kernel.beaverton.ibm.com [9.47.67.96]) by d01av03.pok.ibm.com (8.14.4/8.13.1/NCO v10.0 AVin) with ESMTP id q062oLAW029843; Fri, 6 Jan 2012 00:50:21 -0200 Received: by kernel.beaverton.ibm.com (Postfix, from userid 1056) id 592E11E74FB; Thu, 5 Jan 2012 18:50:20 -0800 (PST) From: John Stultz To: linux-input@vger.kernel.org Cc: John Stultz , Dmitry Torokhov , Daniel Kurtz , =?UTF-8?q?Arve=20Hj=C3=B8nnev=C3=A5g?= Subject: [RFC][PATCH] Input: Add infrastrucutre for selecting clockid for event time stamps. Date: Thu, 5 Jan 2012 18:50:12 -0800 Message-Id: <1325818212-24752-1-git-send-email-john.stultz@linaro.org> X-Mailer: git-send-email 1.7.3.2.146.gca209 MIME-Version: 1.0 x-cbid: 12010602-5930-0000-0000-000003D7079E Here's another revision, incorperating Dmitry's suggestion. As noted by Arve and others, since wall time can jump backwards, it is difficult to use for input because one cannot determine if one event occured before another or for how long a key was pressed. However, the timestamp field is part of the kernel ABI, and cannot be changed without possibly breaking existing users. This patch adds a new IOCTL that allows a clockid to be set in the evdev_client struct that will specify which time base to use for event timestamps (ie: CLOCK_MONOTONIC instead of CLOCK_REALTIME). For now we only support CLOCK_MONOTONIC and CLOCK_REALTIME, but in the future we could support other clockids if appropriate. The default remains CLOCK_REALTIME, so we don't change the ABI. CC: Dmitry Torokhov CC: Daniel Kurtz CC: linux-input@vger.kernel.org CC: Arve Hjønnevåg Signed-off-by: John Stultz --- drivers/input/evdev.c | 33 +++++++++++++++++++++++++++++---- include/linux/input.h | 2 ++ 2 files changed, 31 insertions(+), 4 deletions(-) diff --git a/drivers/input/evdev.c b/drivers/input/evdev.c index 4cf2534..4b71484 100644 --- a/drivers/input/evdev.c +++ b/drivers/input/evdev.c @@ -46,6 +46,7 @@ struct evdev_client { struct fasync_struct *fasync; struct evdev *evdev; struct list_head node; + bool timestamp_clkid; unsigned int bufsize; struct input_event buffer[]; }; @@ -54,8 +55,19 @@ static struct evdev *evdev_table[EVDEV_MINORS]; static DEFINE_MUTEX(evdev_table_mutex); static void evdev_pass_event(struct evdev_client *client, - struct input_event *event) + struct input_event *event, + ktime_t mono, ktime_t real) { + struct timespec ts; + + if (client->timestamp_clkid == CLOCK_MONOTONIC) + ts = ktime_to_timespec(mono); + else + ts = ktime_to_timespec(real); + event->time.tv_sec = ts.tv_sec; + event->time.tv_usec = ts.tv_nsec / NSEC_PER_USEC; + + /* Interrupts are disabled, just acquire the lock. */ spin_lock(&client->buffer_lock); @@ -94,8 +106,11 @@ static void evdev_event(struct input_handle *handle, struct evdev *evdev = handle->private; struct evdev_client *client; struct input_event event; + ktime_t time_mono, time_real; + + time_mono = ktime_get(); + time_real = ktime_sub(time_mono, ktime_get_monotonic_offset()); - do_gettimeofday(&event.time); event.type = type; event.code = code; event.value = value; @@ -103,11 +118,12 @@ static void evdev_event(struct input_handle *handle, rcu_read_lock(); client = rcu_dereference(evdev->grab); + if (client) - evdev_pass_event(client, &event); + evdev_pass_event(client, &event, time_mono, time_real); else list_for_each_entry_rcu(client, &evdev->client_list, node) - evdev_pass_event(client, &event); + evdev_pass_event(client, &event, time_mono, time_real); rcu_read_unlock(); @@ -683,6 +699,15 @@ static long evdev_do_ioctl(struct file *file, unsigned int cmd, else return evdev_ungrab(evdev, client); + case EVIOCCLOCKID: + if (copy_from_user(&i, p, sizeof(unsigned int))) + return -EFAULT; + if ((i == CLOCK_MONOTONIC) || (i == CLOCK_REALTIME)) { + client->timestamp_clkid = i; + return 0; + } + return -EINVAL; + case EVIOCGKEYCODE: return evdev_handle_get_keycode(dev, p); diff --git a/include/linux/input.h b/include/linux/input.h index 3862e32..9618e14 100644 --- a/include/linux/input.h +++ b/include/linux/input.h @@ -129,6 +129,8 @@ struct input_keymap_entry { #define EVIOCGRAB _IOW('E', 0x90, int) /* Grab/Release device */ +#define EVIOCCLOCKID _IOW('E', 0xA0, int) /* Set clockid to be used for timestamps */ + /* * Device properties and quirks */