1 /*
2 *
3 * Copyright (C) 2008 Uwe Hermann <[email protected]>
4 * Copyright (C) 2017 Patrick Rudolph <[email protected]>
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 */
nvram_read(u8 addr)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 */
nvram_write(u8 val,u8 addr)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
nvram_updating(void)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 */
rtc_read_clock(struct tm * time)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 */
rtc_write_clock(const struct tm * time)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 }
217