![Christopher S. Hall](/assets/img/avatar_default.png)
Currently, network /system cross-timestamping is performed in the PTP_SYS_OFFSET ioctl. The PTP clock driver reads gettimeofday() and the gettime64() callback provided by the driver. The cross-timestamp is best effort where the latency between the capture of system time (getnstimeofday()) and the device time (driver callback) may be significant. The getcrosststamp() callback and corresponding PTP_SYS_OFFSET_PRECISE ioctl allows the driver to perform this device/system correlation when for example cross timestamp hardware is available. Modern Intel systems can do this for onboard Ethernet controllers using the ART counter. There is virtually zero latency between captures of the ART and network device clock. The capabilities ioctl (PTP_CLOCK_GETCAPS), is augmented allowing applications to query whether or not drivers implement the getcrosststamp callback, providing more precise cross timestamping. Cc: Prarit Bhargava <prarit@redhat.com> Cc: Richard Cochran <richardcochran@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: kevin.b.stanton@intel.com Cc: kevin.j.clarke@intel.com Cc: hpa@zytor.com Cc: jeffrey.t.kirsher@intel.com Cc: netdev@vger.kernel.org Acked-by: Richard Cochran <richardcochran@gmail.com> Signed-off-by: Christopher S. Hall <christopher.s.hall@intel.com> [jstultz: Commit subject tweaks] Signed-off-by: John Stultz <john.stultz@linaro.org>
360 lines
8.5 KiB
C
360 lines
8.5 KiB
C
/*
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* PTP 1588 clock support - character device implementation.
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*
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* Copyright (C) 2010 OMICRON electronics GmbH
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#include <linux/module.h>
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#include <linux/posix-clock.h>
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#include <linux/poll.h>
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#include <linux/sched.h>
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#include <linux/slab.h>
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#include <linux/timekeeping.h>
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#include "ptp_private.h"
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static int ptp_disable_pinfunc(struct ptp_clock_info *ops,
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enum ptp_pin_function func, unsigned int chan)
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{
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struct ptp_clock_request rq;
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int err = 0;
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memset(&rq, 0, sizeof(rq));
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switch (func) {
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case PTP_PF_NONE:
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break;
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case PTP_PF_EXTTS:
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rq.type = PTP_CLK_REQ_EXTTS;
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rq.extts.index = chan;
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err = ops->enable(ops, &rq, 0);
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break;
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case PTP_PF_PEROUT:
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rq.type = PTP_CLK_REQ_PEROUT;
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rq.perout.index = chan;
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err = ops->enable(ops, &rq, 0);
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break;
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case PTP_PF_PHYSYNC:
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break;
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default:
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return -EINVAL;
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}
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return err;
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}
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int ptp_set_pinfunc(struct ptp_clock *ptp, unsigned int pin,
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enum ptp_pin_function func, unsigned int chan)
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{
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struct ptp_clock_info *info = ptp->info;
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struct ptp_pin_desc *pin1 = NULL, *pin2 = &info->pin_config[pin];
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unsigned int i;
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/* Check to see if any other pin previously had this function. */
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for (i = 0; i < info->n_pins; i++) {
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if (info->pin_config[i].func == func &&
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info->pin_config[i].chan == chan) {
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pin1 = &info->pin_config[i];
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break;
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}
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}
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if (pin1 && i == pin)
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return 0;
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/* Check the desired function and channel. */
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switch (func) {
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case PTP_PF_NONE:
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break;
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case PTP_PF_EXTTS:
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if (chan >= info->n_ext_ts)
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return -EINVAL;
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break;
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case PTP_PF_PEROUT:
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if (chan >= info->n_per_out)
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return -EINVAL;
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break;
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case PTP_PF_PHYSYNC:
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if (chan != 0)
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return -EINVAL;
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default:
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return -EINVAL;
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}
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if (info->verify(info, pin, func, chan)) {
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pr_err("driver cannot use function %u on pin %u\n", func, chan);
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return -EOPNOTSUPP;
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}
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/* Disable whatever function was previously assigned. */
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if (pin1) {
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ptp_disable_pinfunc(info, func, chan);
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pin1->func = PTP_PF_NONE;
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pin1->chan = 0;
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}
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ptp_disable_pinfunc(info, pin2->func, pin2->chan);
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pin2->func = func;
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pin2->chan = chan;
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return 0;
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}
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int ptp_open(struct posix_clock *pc, fmode_t fmode)
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{
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return 0;
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}
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long ptp_ioctl(struct posix_clock *pc, unsigned int cmd, unsigned long arg)
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{
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struct ptp_clock_caps caps;
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struct ptp_clock_request req;
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struct ptp_sys_offset *sysoff = NULL;
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struct ptp_sys_offset_precise precise_offset;
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struct ptp_pin_desc pd;
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struct ptp_clock *ptp = container_of(pc, struct ptp_clock, clock);
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struct ptp_clock_info *ops = ptp->info;
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struct ptp_clock_time *pct;
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struct timespec64 ts;
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struct system_device_crosststamp xtstamp;
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int enable, err = 0;
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unsigned int i, pin_index;
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switch (cmd) {
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case PTP_CLOCK_GETCAPS:
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memset(&caps, 0, sizeof(caps));
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caps.max_adj = ptp->info->max_adj;
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caps.n_alarm = ptp->info->n_alarm;
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caps.n_ext_ts = ptp->info->n_ext_ts;
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caps.n_per_out = ptp->info->n_per_out;
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caps.pps = ptp->info->pps;
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caps.n_pins = ptp->info->n_pins;
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caps.cross_timestamping = ptp->info->getcrosststamp != NULL;
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if (copy_to_user((void __user *)arg, &caps, sizeof(caps)))
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err = -EFAULT;
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break;
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case PTP_EXTTS_REQUEST:
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if (copy_from_user(&req.extts, (void __user *)arg,
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sizeof(req.extts))) {
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err = -EFAULT;
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break;
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}
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if (req.extts.index >= ops->n_ext_ts) {
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err = -EINVAL;
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break;
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}
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req.type = PTP_CLK_REQ_EXTTS;
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enable = req.extts.flags & PTP_ENABLE_FEATURE ? 1 : 0;
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err = ops->enable(ops, &req, enable);
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break;
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case PTP_PEROUT_REQUEST:
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if (copy_from_user(&req.perout, (void __user *)arg,
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sizeof(req.perout))) {
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err = -EFAULT;
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break;
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}
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if (req.perout.index >= ops->n_per_out) {
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err = -EINVAL;
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break;
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}
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req.type = PTP_CLK_REQ_PEROUT;
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enable = req.perout.period.sec || req.perout.period.nsec;
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err = ops->enable(ops, &req, enable);
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break;
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case PTP_ENABLE_PPS:
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if (!capable(CAP_SYS_TIME))
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return -EPERM;
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req.type = PTP_CLK_REQ_PPS;
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enable = arg ? 1 : 0;
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err = ops->enable(ops, &req, enable);
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break;
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case PTP_SYS_OFFSET_PRECISE:
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if (!ptp->info->getcrosststamp) {
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err = -EOPNOTSUPP;
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break;
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}
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err = ptp->info->getcrosststamp(ptp->info, &xtstamp);
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if (err)
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break;
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ts = ktime_to_timespec64(xtstamp.device);
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precise_offset.device.sec = ts.tv_sec;
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precise_offset.device.nsec = ts.tv_nsec;
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ts = ktime_to_timespec64(xtstamp.sys_realtime);
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precise_offset.sys_realtime.sec = ts.tv_sec;
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precise_offset.sys_realtime.nsec = ts.tv_nsec;
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ts = ktime_to_timespec64(xtstamp.sys_monoraw);
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precise_offset.sys_monoraw.sec = ts.tv_sec;
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precise_offset.sys_monoraw.nsec = ts.tv_nsec;
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if (copy_to_user((void __user *)arg, &precise_offset,
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sizeof(precise_offset)))
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err = -EFAULT;
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break;
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case PTP_SYS_OFFSET:
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sysoff = kmalloc(sizeof(*sysoff), GFP_KERNEL);
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if (!sysoff) {
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err = -ENOMEM;
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break;
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}
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if (copy_from_user(sysoff, (void __user *)arg,
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sizeof(*sysoff))) {
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err = -EFAULT;
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break;
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}
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if (sysoff->n_samples > PTP_MAX_SAMPLES) {
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err = -EINVAL;
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break;
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}
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pct = &sysoff->ts[0];
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for (i = 0; i < sysoff->n_samples; i++) {
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getnstimeofday64(&ts);
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pct->sec = ts.tv_sec;
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pct->nsec = ts.tv_nsec;
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pct++;
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ptp->info->gettime64(ptp->info, &ts);
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pct->sec = ts.tv_sec;
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pct->nsec = ts.tv_nsec;
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pct++;
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}
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getnstimeofday64(&ts);
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pct->sec = ts.tv_sec;
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pct->nsec = ts.tv_nsec;
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if (copy_to_user((void __user *)arg, sysoff, sizeof(*sysoff)))
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err = -EFAULT;
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break;
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case PTP_PIN_GETFUNC:
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if (copy_from_user(&pd, (void __user *)arg, sizeof(pd))) {
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err = -EFAULT;
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break;
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}
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pin_index = pd.index;
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if (pin_index >= ops->n_pins) {
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err = -EINVAL;
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break;
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}
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if (mutex_lock_interruptible(&ptp->pincfg_mux))
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return -ERESTARTSYS;
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pd = ops->pin_config[pin_index];
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mutex_unlock(&ptp->pincfg_mux);
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if (!err && copy_to_user((void __user *)arg, &pd, sizeof(pd)))
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err = -EFAULT;
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break;
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case PTP_PIN_SETFUNC:
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if (copy_from_user(&pd, (void __user *)arg, sizeof(pd))) {
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err = -EFAULT;
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break;
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}
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pin_index = pd.index;
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if (pin_index >= ops->n_pins) {
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err = -EINVAL;
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break;
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}
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if (mutex_lock_interruptible(&ptp->pincfg_mux))
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return -ERESTARTSYS;
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err = ptp_set_pinfunc(ptp, pin_index, pd.func, pd.chan);
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mutex_unlock(&ptp->pincfg_mux);
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break;
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default:
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err = -ENOTTY;
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break;
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}
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kfree(sysoff);
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return err;
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}
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unsigned int ptp_poll(struct posix_clock *pc, struct file *fp, poll_table *wait)
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{
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struct ptp_clock *ptp = container_of(pc, struct ptp_clock, clock);
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poll_wait(fp, &ptp->tsev_wq, wait);
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return queue_cnt(&ptp->tsevq) ? POLLIN : 0;
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}
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#define EXTTS_BUFSIZE (PTP_BUF_TIMESTAMPS * sizeof(struct ptp_extts_event))
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ssize_t ptp_read(struct posix_clock *pc,
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uint rdflags, char __user *buf, size_t cnt)
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{
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struct ptp_clock *ptp = container_of(pc, struct ptp_clock, clock);
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struct timestamp_event_queue *queue = &ptp->tsevq;
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struct ptp_extts_event *event;
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unsigned long flags;
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size_t qcnt, i;
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int result;
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if (cnt % sizeof(struct ptp_extts_event) != 0)
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return -EINVAL;
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if (cnt > EXTTS_BUFSIZE)
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cnt = EXTTS_BUFSIZE;
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cnt = cnt / sizeof(struct ptp_extts_event);
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if (mutex_lock_interruptible(&ptp->tsevq_mux))
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return -ERESTARTSYS;
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if (wait_event_interruptible(ptp->tsev_wq,
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ptp->defunct || queue_cnt(queue))) {
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mutex_unlock(&ptp->tsevq_mux);
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return -ERESTARTSYS;
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}
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if (ptp->defunct) {
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mutex_unlock(&ptp->tsevq_mux);
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return -ENODEV;
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}
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event = kmalloc(EXTTS_BUFSIZE, GFP_KERNEL);
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if (!event) {
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mutex_unlock(&ptp->tsevq_mux);
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return -ENOMEM;
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}
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spin_lock_irqsave(&queue->lock, flags);
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qcnt = queue_cnt(queue);
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if (cnt > qcnt)
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cnt = qcnt;
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for (i = 0; i < cnt; i++) {
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event[i] = queue->buf[queue->head];
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queue->head = (queue->head + 1) % PTP_MAX_TIMESTAMPS;
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}
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spin_unlock_irqrestore(&queue->lock, flags);
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cnt = cnt * sizeof(struct ptp_extts_event);
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mutex_unlock(&ptp->tsevq_mux);
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result = cnt;
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if (copy_to_user(buf, event, cnt))
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result = -EFAULT;
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kfree(event);
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return result;
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}
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