arch/um/drivers/rtc_user.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2020 Intel Corporation
   4  * Author: Johannes Berg <johannes@sipsolutions.net>
   5  */
   6 #include <os.h>
   7 #include <errno.h>
   8 #include <sched.h>
   9 #include <unistd.h>
  10 #include <kern_util.h>
  11 #include <sys/select.h>
  12 #include <stdio.h>
  13 #include <sys/timerfd.h>
  14 #include "rtc.h"
  15
  16 static int uml_rtc_irq_fds[2];
  17
  18 void uml_rtc_send_timetravel_alarm(void)
  19 {
  20         unsigned long long c = 1;
  21
  22         CATCH_EINTR(write(uml_rtc_irq_fds[1], &c, sizeof(c)));
  23 }
  24
  25 int uml_rtc_start(bool timetravel)
  26 {
  27         int err;
  28
  29         if (timetravel) {
  30                 int err = os_pipe(uml_rtc_irq_fds, 1, 1);
  31                 if (err)
  32                         goto fail;
  33         } else {
  34                 uml_rtc_irq_fds[0] = timerfd_create(CLOCK_REALTIME, TFD_CLOEXEC);
  35                 if (uml_rtc_irq_fds[0] < 0) {
  36                         err = -errno;
  37                         goto fail;
  38                 }
  39
  40                 /* apparently timerfd won't send SIGIO, use workaround */
  41                 sigio_broken(uml_rtc_irq_fds[0]);
  42                 err = add_sigio_fd(uml_rtc_irq_fds[0]);
  43                 if (err < 0) {
  44                         close(uml_rtc_irq_fds[0]);
  45                         goto fail;
  46                 }
  47         }
  48
  49         return uml_rtc_irq_fds[0];
  50 fail:
  51         uml_rtc_stop(timetravel);
  52         return err;
  53 }
  54
  55 int uml_rtc_enable_alarm(unsigned long long delta_seconds)
  56 {
  57         struct itimerspec it = {
  58                 .it_value = {
  59                         .tv_sec = delta_seconds,
  60                 },
  61         };
  62
  63         if (timerfd_settime(uml_rtc_irq_fds[0], 0, &it, NULL))
  64                 return -errno;
  65         return 0;
  66 }
  67
  68 void uml_rtc_disable_alarm(void)
  69 {
  70         uml_rtc_enable_alarm(0);
  71 }
  72
  73 void uml_rtc_stop(bool timetravel)
  74 {
  75         if (timetravel)
  76                 os_close_file(uml_rtc_irq_fds[1]);
  77         else
  78                 ignore_sigio_fd(uml_rtc_irq_fds[0]);
  79         os_close_file(uml_rtc_irq_fds[0]);
  80 }