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 <stdbool.h>
   7 #include <os.h>
   8 #include <errno.h>
   9 #include <sched.h>
  10 #include <unistd.h>
  11 #include <kern_util.h>
  12 #include <sys/select.h>
  13 #include <stdio.h>
  14 #include <sys/timerfd.h>
  15 #include "rtc.h"
  16
  17 static int uml_rtc_irq_fds[2];
  18
  19 void uml_rtc_send_timetravel_alarm(void)
  20 {
  21         unsigned long long c = 1;
  22
  23         CATCH_EINTR(write(uml_rtc_irq_fds[1], &c, sizeof(c)));
  24 }
  25
  26 int uml_rtc_start(bool timetravel)
  27 {
  28         int err;
  29
  30         if (timetravel) {
  31                 int err = os_pipe(uml_rtc_irq_fds, 1, 1);
  32                 if (err)
  33                         goto fail;
  34         } else {
  35                 uml_rtc_irq_fds[0] = timerfd_create(CLOCK_REALTIME, TFD_CLOEXEC);
  36                 if (uml_rtc_irq_fds[0] < 0) {
  37                         err = -errno;
  38                         goto fail;
  39                 }
  40
  41                 /* apparently timerfd won't send SIGIO, use workaround */
  42                 sigio_broken(uml_rtc_irq_fds[0]);
  43                 err = add_sigio_fd(uml_rtc_irq_fds[0]);
  44                 if (err < 0) {
  45                         close(uml_rtc_irq_fds[0]);
  46                         goto fail;
  47                 }
  48         }
  49
  50         return uml_rtc_irq_fds[0];
  51 fail:
  52         uml_rtc_stop(timetravel);
  53         return err;
  54 }
  55
  56 int uml_rtc_enable_alarm(unsigned long long delta_seconds)
  57 {
  58         struct itimerspec it = {
  59                 .it_value = {
  60                         .tv_sec = delta_seconds,
  61                 },
  62         };
  63
  64         if (timerfd_settime(uml_rtc_irq_fds[0], 0, &it, NULL))
  65                 return -errno;
  66         return 0;
  67 }
  68
  69 void uml_rtc_disable_alarm(void)
  70 {
  71         uml_rtc_enable_alarm(0);
  72 }
  73
  74 void uml_rtc_stop(bool timetravel)
  75 {
  76         if (timetravel)
  77                 os_close_file(uml_rtc_irq_fds[1]);
  78         else
  79                 ignore_sigio_fd(uml_rtc_irq_fds[0]);
  80         os_close_file(uml_rtc_irq_fds[0]);
  81 }