arch/powerpc/kernel/rtas-rtc.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <linux/kernel.h>
   3 #include <linux/time.h>
   4 #include <linux/timer.h>
   5 #include <linux/init.h>
   6 #include <linux/rtc.h>
   7 #include <linux/delay.h>
   8 #include <linux/ratelimit.h>
   9 #include <asm/prom.h>
  10 #include <asm/rtas.h>
  11 #include <asm/time.h>
  12
  13
  14 #define MAX_RTC_WAIT 5000       /* 5 sec */
  15 #define RTAS_CLOCK_BUSY (-2)
  16 unsigned long __init rtas_get_boot_time(void)
  17 {
  18         int ret[8];
  19         int error;
  20         unsigned int wait_time;
  21         u64 max_wait_tb;
  22
  23         max_wait_tb = get_tb() + tb_ticks_per_usec * 1000 * MAX_RTC_WAIT;
  24         do {
  25                 error = rtas_call(rtas_token("get-time-of-day"), 0, 8, ret);
  26
  27                 wait_time = rtas_busy_delay_time(error);
  28                 if (wait_time) {
  29                         /* This is boot time so we spin. */
  30                         udelay(wait_time*1000);
  31                 }
  32         } while (wait_time && (get_tb() < max_wait_tb));
  33
  34         if (error != 0) {
  35                 printk_ratelimited(KERN_WARNING
  36                                    "error: reading the clock failed (%d)\n",
  37                                    error);
  38                 return 0;
  39         }
  40
  41         return mktime(ret[0], ret[1], ret[2], ret[3], ret[4], ret[5]);
  42 }
  43
  44 /* NOTE: get_rtc_time will get an error if executed in interrupt context
  45  * and if a delay is needed to read the clock.  In this case we just
  46  * silently return without updating rtc_tm.
  47  */
  48 void rtas_get_rtc_time(struct rtc_time *rtc_tm)
  49 {
  50         int ret[8];
  51         int error;
  52         unsigned int wait_time;
  53         u64 max_wait_tb;
  54
  55         max_wait_tb = get_tb() + tb_ticks_per_usec * 1000 * MAX_RTC_WAIT;
  56         do {
  57                 error = rtas_call(rtas_token("get-time-of-day"), 0, 8, ret);
  58
  59                 wait_time = rtas_busy_delay_time(error);
  60                 if (wait_time) {
  61                         if (in_interrupt()) {
  62                                 memset(rtc_tm, 0, sizeof(struct rtc_time));
  63                                 printk_ratelimited(KERN_WARNING
  64                                                    "error: reading clock "
  65                                                    "would delay interrupt\n");
  66                                 return; /* delay not allowed */
  67                         }
  68                         msleep(wait_time);
  69                 }
  70         } while (wait_time && (get_tb() < max_wait_tb));
  71
  72         if (error != 0) {
  73                 printk_ratelimited(KERN_WARNING
  74                                    "error: reading the clock failed (%d)\n",
  75                                    error);
  76                 return;
  77         }
  78
  79         rtc_tm->tm_sec = ret[5];
  80         rtc_tm->tm_min = ret[4];
  81         rtc_tm->tm_hour = ret[3];
  82         rtc_tm->tm_mday = ret[2];
  83         rtc_tm->tm_mon = ret[1] - 1;
  84         rtc_tm->tm_year = ret[0] - 1900;
  85 }
  86
  87 int rtas_set_rtc_time(struct rtc_time *tm)
  88 {
  89         int error, wait_time;
  90         u64 max_wait_tb;
  91
  92         max_wait_tb = get_tb() + tb_ticks_per_usec * 1000 * MAX_RTC_WAIT;
  93         do {
  94                 error = rtas_call(rtas_token("set-time-of-day"), 7, 1, NULL,
  95                                   tm->tm_year + 1900, tm->tm_mon + 1,
  96                                   tm->tm_mday, tm->tm_hour, tm->tm_min,
  97                                   tm->tm_sec, 0);
  98
  99                 wait_time = rtas_busy_delay_time(error);
 100                 if (wait_time) {
 101                         if (in_interrupt())
 102                                 return 1;       /* probably decrementer */
 103                         msleep(wait_time);
 104                 }
 105         } while (wait_time && (get_tb() < max_wait_tb));
 106
 107         if (error != 0)
 108                 printk_ratelimited(KERN_WARNING
 109                                    "error: setting the clock failed (%d)\n",
 110                                    error);
 111
 112         return 0;
 113 }