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

   1 /*
   2  * PowerNV Real Time Clock.
   3  *
   4  * Copyright 2011 IBM Corp.
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the License, or (at your option) any later version.
  10  */
  11
  12
  13 #include <linux/kernel.h>
  14 #include <linux/time.h>
  15 #include <linux/bcd.h>
  16 #include <linux/rtc.h>
  17 #include <linux/delay.h>
  18 #include <linux/platform_device.h>
  19 #include <linux/of_platform.h>
  20
  21 #include <asm/opal.h>
  22 #include <asm/firmware.h>
  23 #include <asm/machdep.h>
  24
  25 static void opal_to_tm(u32 y_m_d, u64 h_m_s_ms, struct rtc_time *tm)
  26 {
  27         tm->tm_year     = ((bcd2bin(y_m_d >> 24) * 100) +
  28                            bcd2bin((y_m_d >> 16) & 0xff)) - 1900;
  29         tm->tm_mon      = bcd2bin((y_m_d >> 8) & 0xff) - 1;
  30         tm->tm_mday     = bcd2bin(y_m_d & 0xff);
  31         tm->tm_hour     = bcd2bin((h_m_s_ms >> 56) & 0xff);
  32         tm->tm_min      = bcd2bin((h_m_s_ms >> 48) & 0xff);
  33         tm->tm_sec      = bcd2bin((h_m_s_ms >> 40) & 0xff);
  34         tm->tm_wday     = -1;
  35 }
  36
  37 unsigned long __init opal_get_boot_time(void)
  38 {
  39         struct rtc_time tm;
  40         u32 y_m_d;
  41         u64 h_m_s_ms;
  42         __be32 __y_m_d;
  43         __be64 __h_m_s_ms;
  44         long rc = OPAL_BUSY;
  45
  46         if (!opal_check_token(OPAL_RTC_READ))
  47                 return 0;
  48
  49         while (rc == OPAL_BUSY || rc == OPAL_BUSY_EVENT) {
  50                 rc = opal_rtc_read(&__y_m_d, &__h_m_s_ms);
  51                 if (rc == OPAL_BUSY_EVENT)
  52                         opal_poll_events(NULL);
  53                 else if (rc == OPAL_BUSY)
  54                         mdelay(10);
  55         }
  56         if (rc != OPAL_SUCCESS)
  57                 return 0;
  58
  59         y_m_d = be32_to_cpu(__y_m_d);
  60         h_m_s_ms = be64_to_cpu(__h_m_s_ms);
  61         opal_to_tm(y_m_d, h_m_s_ms, &tm);
  62         return mktime(tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday,
  63                       tm.tm_hour, tm.tm_min, tm.tm_sec);
  64 }
  65
  66 static __init int opal_time_init(void)
  67 {
  68         struct platform_device *pdev;
  69         struct device_node *rtc;
  70
  71         rtc = of_find_node_by_path("/ibm,opal/rtc");
  72         if (rtc) {
  73                 pdev = of_platform_device_create(rtc, "opal-rtc", NULL);
  74                 of_node_put(rtc);
  75         } else {
  76                 if (opal_check_token(OPAL_RTC_READ) ||
  77                     opal_check_token(OPAL_READ_TPO))
  78                         pdev = platform_device_register_simple("opal-rtc", -1,
  79                                                                NULL, 0);
  80                 else
  81                         return -ENODEV;
  82         }
  83
  84         return PTR_ERR_OR_ZERO(pdev);
  85 }
  86 machine_subsys_initcall(powernv, opal_time_init);