arch/powerpc/platforms/powernv/opal-rtc.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * PowerNV Real Time Clock.
   4  *
   5  * Copyright 2011 IBM Corp.
   6  */
   7
   8
   9 #include <linux/kernel.h>
  10 #include <linux/time.h>
  11 #include <linux/bcd.h>
  12 #include <linux/rtc.h>
  13 #include <linux/delay.h>
  14 #include <linux/platform_device.h>
  15 #include <linux/of_platform.h>
  16
  17 #include <asm/opal.h>
  18 #include <asm/firmware.h>
  19 #include <asm/machdep.h>
  20
  21 static void opal_to_tm(u32 y_m_d, u64 h_m_s_ms, struct rtc_time *tm)
  22 {
  23         tm->tm_year     = ((bcd2bin(y_m_d >> 24) * 100) +
  24                            bcd2bin((y_m_d >> 16) & 0xff)) - 1900;
  25         tm->tm_mon      = bcd2bin((y_m_d >> 8) & 0xff) - 1;
  26         tm->tm_mday     = bcd2bin(y_m_d & 0xff);
  27         tm->tm_hour     = bcd2bin((h_m_s_ms >> 56) & 0xff);
  28         tm->tm_min      = bcd2bin((h_m_s_ms >> 48) & 0xff);
  29         tm->tm_sec      = bcd2bin((h_m_s_ms >> 40) & 0xff);
  30         tm->tm_wday     = -1;
  31 }
  32
  33 time64_t __init opal_get_boot_time(void)
  34 {
  35         struct rtc_time tm;
  36         u32 y_m_d;
  37         u64 h_m_s_ms;
  38         __be32 __y_m_d;
  39         __be64 __h_m_s_ms;
  40         long rc = OPAL_BUSY;
  41
  42         if (!opal_check_token(OPAL_RTC_READ))
  43                 return 0;
  44
  45         while (rc == OPAL_BUSY || rc == OPAL_BUSY_EVENT) {
  46                 rc = opal_rtc_read(&__y_m_d, &__h_m_s_ms);
  47                 if (rc == OPAL_BUSY_EVENT) {
  48                         mdelay(OPAL_BUSY_DELAY_MS);
  49                         opal_poll_events(NULL);
  50                 } else if (rc == OPAL_BUSY) {
  51                         mdelay(OPAL_BUSY_DELAY_MS);
  52                 }
  53         }
  54         if (rc != OPAL_SUCCESS)
  55                 return 0;
  56
  57         y_m_d = be32_to_cpu(__y_m_d);
  58         h_m_s_ms = be64_to_cpu(__h_m_s_ms);
  59         opal_to_tm(y_m_d, h_m_s_ms, &tm);
  60         return rtc_tm_to_time64(&tm);
  61 }
  62
  63 static __init int opal_time_init(void)
  64 {
  65         struct platform_device *pdev;
  66         struct device_node *rtc;
  67
  68         rtc = of_find_node_by_path("/ibm,opal/rtc");
  69         if (rtc) {
  70                 pdev = of_platform_device_create(rtc, "opal-rtc", NULL);
  71                 of_node_put(rtc);
  72         } else {
  73                 if (opal_check_token(OPAL_RTC_READ) ||
  74                     opal_check_token(OPAL_READ_TPO))
  75                         pdev = platform_device_register_simple("opal-rtc", -1,
  76                                                                NULL, 0);
  77                 else
  78                         return -ENODEV;
  79         }
  80
  81         return PTR_ERR_OR_ZERO(pdev);
  82 }
  83 machine_subsys_initcall(powernv, opal_time_init);