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