payloads/libpayload/drivers/nvram.c

   1 /*
   2  *
   3  * Copyright (C) 2008 Uwe Hermann <uwe@hermann-uwe.de>
   4  * Copyright (C) 2017 Patrick Rudolph <siro@das-labor.org>
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  * 3. The name of the author may not be used to endorse or promote products
  15  *    derived from this software without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  */
  29
  30 /*
  31  * Datasheet:
  32  *  - Name: MC146818: Real-time Clock Plus RAM (RTC)
  33  *  - PDF: http://www.freescale.com/files/microcontrollers/doc/data_sheet/MC146818.pdf
  34  *  - Order number: MC146818/D
  35  */
  36
  37 /*
  38  * See also:
  39  * http://bochs.sourceforge.net/techspec/CMOS-reference.txt
  40  * http://www.bioscentral.com/misc/cmosmap.htm
  41  */
  42 #include <libpayload-config.h>
  43 #include <libpayload.h>
  44
  45 /**
  46  * PCs can have either 64 (very old ones), 128, or 256 bytes of CMOS RAM.
  47  *
  48  * Usually you access the lower 128 CMOS bytes via I/O port 0x70/0x71.
  49  * For more recent chipsets with 256 bytes, you have to access the upper
  50  * 128 bytes (128-255) using two different registers, usually 0x72/0x73.
  51  *
  52  * On some chipsets this can be different, though. The VIA VT8237R for example
  53  * only recognizes the ports 0x74/0x75 for accessing the high 128 CMOS bytes
  54  * (as seems to be the case for multiple VIA chipsets).
  55  *
  56  * It's very chipset-specific if and how the upper 128 bytes are enabled at
  57  * all, but this work should be done in coreboot anyway. Libpayload assumes
  58  * that coreboot has properly enabled access to the upper 128 bytes and
  59  * doesn't try to do this on its own.
  60  */
  61 #define RTC_PORT_STANDARD      0x70
  62 #if CONFIG(LP_RTC_PORT_EXTENDED_VIA)
  63 #define RTC_PORT_EXTENDED      0x74
  64 #else
  65 #define RTC_PORT_EXTENDED      0x72
  66 #endif
  67
  68 /**
  69  * Read a byte from the specified NVRAM address.
  70  *
  71  * @param addr The NVRAM address to read a byte from.
  72  * @return The byte at the given NVRAM address.
  73  */
  74 u8 nvram_read(u8 addr)
  75 {
  76         u16 rtc_port = addr < 128 ? RTC_PORT_STANDARD : RTC_PORT_EXTENDED;
  77
  78         outb(addr, rtc_port);
  79         return inb(rtc_port + 1);
  80 }
  81
  82 /**
  83  * Write a byte to the specified NVRAM address.
  84  *
  85  * @param val The byte to write to NVRAM.
  86  * @param addr The NVRAM address to write to.
  87  */
  88 void nvram_write(u8 val, u8 addr)
  89 {
  90         u16 rtc_port = addr < 128 ? RTC_PORT_STANDARD : RTC_PORT_EXTENDED;
  91
  92         outb(addr, rtc_port);
  93         outb(val, rtc_port + 1);
  94 }
  95
  96 /**
  97  * Return 1 if the NVRAM is currently updating and a 0 otherwise
  98  * @return A 1 if the NVRAM is updating and 0 otherwise
  99  */
 100
 101 int nvram_updating(void)
 102 {
 103        return (nvram_read(NVRAM_RTC_FREQ_SELECT) & NVRAM_RTC_UIP) ? 1 : 0;
 104 }
 105
 106 /**
 107  * Get the current time and date from the RTC
 108  *
 109  * @param time A pointer to a broken-down time structure
 110  */
 111 void rtc_read_clock(struct tm *time)
 112 {
 113         u16 timeout = 10000;
 114         u8 statusB;
 115         u8 reg8;
 116
 117         memset(time, 0, sizeof(*time));
 118
 119         while (nvram_updating())
 120                 if (!timeout--)
 121                         return;
 122
 123         statusB = nvram_read(NVRAM_RTC_STATUSB);
 124
 125         if (!(statusB & NVRAM_RTC_FORMAT_BINARY)) {
 126                 time->tm_mon = bcd2dec(nvram_read(NVRAM_RTC_MONTH)) - 1;
 127                 time->tm_sec = bcd2dec(nvram_read(NVRAM_RTC_SECONDS));
 128                 time->tm_min = bcd2dec(nvram_read(NVRAM_RTC_MINUTES));
 129                 time->tm_mday = bcd2dec(nvram_read(NVRAM_RTC_DAY));
 130
 131                 if (!(statusB & NVRAM_RTC_FORMAT_24HOUR)) {
 132                         reg8 = nvram_read(NVRAM_RTC_HOURS);
 133                         time->tm_hour = bcd2dec(reg8 & 0x7f);
 134                         time->tm_hour += (reg8 & 0x80) ? 12 : 0;
 135                         time->tm_hour %= 24;
 136                 } else {
 137                         time->tm_hour = bcd2dec(nvram_read(NVRAM_RTC_HOURS));
 138                 }
 139                 time->tm_year = bcd2dec(nvram_read(NVRAM_RTC_YEAR));
 140         } else {
 141                 time->tm_mon = nvram_read(NVRAM_RTC_MONTH) - 1;
 142                 time->tm_sec = nvram_read(NVRAM_RTC_SECONDS);
 143                 time->tm_min = nvram_read(NVRAM_RTC_MINUTES);
 144                 time->tm_mday = nvram_read(NVRAM_RTC_DAY);
 145                 if (!(statusB & NVRAM_RTC_FORMAT_24HOUR)) {
 146                         reg8 = nvram_read(NVRAM_RTC_HOURS);
 147                         time->tm_hour = reg8 & 0x7f;
 148                         time->tm_hour += (reg8 & 0x80) ? 12 : 0;
 149                         time->tm_hour %= 24;
 150                 } else {
 151                         time->tm_hour = nvram_read(NVRAM_RTC_HOURS);
 152                 }
 153                 time->tm_year = nvram_read(NVRAM_RTC_YEAR);
 154         }
 155
 156         /* Instead of finding the century register,
 157            we just make an assumption that if the year value is
 158            less then 80, then it is 2000+
 159         */
 160         if (time->tm_year < 80)
 161                 time->tm_year += 100;
 162 }
 163
 164 /**
 165  * Write the current time and date to the RTC
 166  *
 167  * @param time A pointer to a broken-down time structure
 168  */
 169 void rtc_write_clock(const struct tm *time)
 170 {
 171         u16 timeout = 10000;
 172         u8 statusB;
 173         u8 reg8, year;
 174
 175         while (nvram_updating())
 176                 if (!timeout--)
 177                         return;
 178
 179         statusB = nvram_read(NVRAM_RTC_STATUSB);
 180
 181         year = time->tm_year;
 182         if (year > 100)
 183                 year -= 100;
 184
 185         if (!(statusB & NVRAM_RTC_FORMAT_BINARY)) {
 186                 nvram_write(dec2bcd(time->tm_mon + 1), NVRAM_RTC_MONTH);
 187                 nvram_write(dec2bcd(time->tm_sec), NVRAM_RTC_SECONDS);
 188                 nvram_write(dec2bcd(time->tm_min), NVRAM_RTC_MINUTES);
 189                 nvram_write(dec2bcd(time->tm_mday), NVRAM_RTC_DAY);
 190                 if (!(statusB & NVRAM_RTC_FORMAT_24HOUR)) {
 191                         if (time->tm_hour > 12)
 192                                 reg8 = dec2bcd(time->tm_hour - 12) | 0x80;
 193                         else
 194                                 reg8 = dec2bcd(time->tm_hour);
 195                 } else {
 196                         reg8 = dec2bcd(time->tm_hour);
 197                 }
 198                 nvram_write(reg8, NVRAM_RTC_HOURS);
 199                 nvram_write(dec2bcd(year), NVRAM_RTC_YEAR);
 200         } else {
 201                 nvram_write(time->tm_mon + 1, NVRAM_RTC_MONTH);
 202                 nvram_write(time->tm_sec, NVRAM_RTC_SECONDS);
 203                 nvram_write(time->tm_min, NVRAM_RTC_MINUTES);
 204                 nvram_write(time->tm_mday, NVRAM_RTC_DAY);
 205                 if (!(statusB & NVRAM_RTC_FORMAT_24HOUR)) {
 206                         if (time->tm_hour > 12)
 207                                 reg8 = (time->tm_hour - 12) | 0x80;
 208                         else
 209                                 reg8 = time->tm_hour;
 210                 } else {
 211                         reg8 = time->tm_hour;
 212                 }
 213                 nvram_write(reg8, NVRAM_RTC_HOURS);
 214                 nvram_write(year, NVRAM_RTC_YEAR);
 215         }
 216 }