source: trunk/minix/drivers/cmos/cmos.c@ 20

Last change on this file since 20 was 9, checked in by Mattia Monga, 14 years ago

Minix 3.1.2a
File size: 7.7 KB
Line 
1/* This file contains a device driver that can access the CMOS chip to
2 * get or set the system time. It drives the special file:
3 *
4 * /dev/cmos - CMOS chip
5 *
6 * Changes:
7 * Aug 04, 2005 Created. Read CMOS time. (Jorrit N. Herder)
8 *
9 * Manufacturers usually use the ID value of the IBM model they emulate.
10 * However some manufacturers, notably HP and COMPAQ, have had different
11 * ideas in the past.
12 *
13 * Machine ID byte information source:
14 * _The Programmer's PC Sourcebook_ by Thom Hogan,
15 * published by Microsoft Press
16 */
17
18#include "../drivers.h"
19#include <sys/ioc_cmos.h>
20#include <time.h>
21#include <ibm/cmos.h>
22#include <ibm/bios.h>
23
24extern int errno; /* error number for PM calls */
25
26FORWARD _PROTOTYPE( int gettime, (int who, int y2kflag, vir_bytes dst_time));
27FORWARD _PROTOTYPE( void reply, (int reply, int replyee, int proc, int s));
28
29FORWARD _PROTOTYPE( int read_register, (int register_address));
30FORWARD _PROTOTYPE( int get_cmostime, (struct tm *tmp, int y2kflag));
31FORWARD _PROTOTYPE( int dec_to_bcd, (int dec));
32FORWARD _PROTOTYPE( int bcd_to_dec, (int bcd));
33
34/*===========================================================================*
35 * main *
36 *===========================================================================*/
37PUBLIC void main(void)
38{
39 message m;
40 int y2kflag;
41 int result;
42 int suspended = NONE;
43 int s;
44
45 while(TRUE) {
46
47 /* Get work. */
48 if (OK != (s=receive(ANY, &m)))
49 panic("CMOS", "attempt to receive work failed", s);
50
51 /* Handle request. */
52 switch(m.m_type) {
53
54 case DEV_OPEN:
55 case DEV_CLOSE:
56 case CANCEL:
57 reply(TASK_REPLY, m.m_source, m.IO_ENDPT, OK);
58 break;
59
60 case DEV_PING:
61 notify(m.m_source);
62 break;
63 case DEV_IOCTL:
64
65 /* Probably best to SUSPEND the caller, CMOS I/O has nasty timeouts.
66 * This way we don't block the rest of the system. First check if
67 * another process is already suspended. We cannot handle multiple
68 * requests at a time.
69 */
70 if (suspended != NONE) {
71 reply(TASK_REPLY, m.m_source, m.IO_ENDPT, EBUSY);
72 break;
73 }
74 suspended = m.IO_ENDPT;
75 reply(TASK_REPLY, m.m_source, m.IO_ENDPT, SUSPEND);
76
77 switch(m.REQUEST) {
78 case CIOCGETTIME: /* get CMOS time */
79 case CIOCGETTIMEY2K:
80 y2kflag = (m.REQUEST = CIOCGETTIME) ? 0 : 1;
81 result = gettime(m.IO_ENDPT, y2kflag, (vir_bytes) m.ADDRESS);
82 break;
83 case CIOCSETTIME:
84 case CIOCSETTIMEY2K:
85 default: /* unsupported ioctl */
86 result = ENOSYS;
87 }
88
89 /* Request completed. Tell the caller to check our status. */
90 notify(m.m_source);
91 break;
92
93 case DEV_STATUS:
94
95 /* The FS calls back to get our status. Revive the suspended
96 * processes and return the status of reading the CMOS.
97 */
98 if (suspended == NONE)
99 reply(DEV_NO_STATUS, m.m_source, NONE, OK);
100 else
101 reply(DEV_REVIVE, m.m_source, suspended, result);
102 suspended = NONE;
103 break;
104
105 case SYN_ALARM: /* shouldn't happen */
106 case SYS_SIG: /* ignore system events */
107 continue;
108
109 default:
110 reply(TASK_REPLY, m.m_source, m.IO_ENDPT, EINVAL);
111 }
112 }
113}
114
115/*===========================================================================*
116 * reply *
117 *===========================================================================*/
118PRIVATE void reply(int code, int replyee, int process, int status)
119{
120 message m;
121 int s;
122
123 m.m_type = code; /* TASK_REPLY or REVIVE */
124 m.REP_STATUS = status; /* result of device operation */
125 m.REP_ENDPT = process; /* which user made the request */
126 if (OK != (s=send(replyee, &m)))
127 panic("CMOS", "sending reply failed", s);
128}
129
130/*===========================================================================*
131 * gettime *
132 *===========================================================================*/
133PRIVATE int gettime(int who, int y2kflag, vir_bytes dst_time)
134{
135 unsigned char mach_id, cmos_state;
136 struct tm time1;
137 int i, s;
138
139 /* First obtain the machine ID to see if we can read the CMOS clock. Only
140 * for PS_386 and PC_AT this is possible. Otherwise, return an error.
141 */
142 sys_vircopy(SELF, BIOS_SEG, (vir_bytes) MACHINE_ID_ADDR,
143 SELF, D, (vir_bytes) &mach_id, MACHINE_ID_SIZE);
144 if (mach_id != PS_386_MACHINE && mach_id != PC_AT_MACHINE) {
145 printf("IS: Machine ID unknown. ID byte = %02x.\n", mach_id);
146 return(EFAULT);
147 }
148
149 /* Now check the CMOS' state to see if we can read a proper time from it.
150 * If the state is crappy, return an error.
151 */
152 cmos_state = read_register(CMOS_STATUS);
153 if (cmos_state & (CS_LOST_POWER | CS_BAD_CHKSUM | CS_BAD_TIME)) {
154 printf( "IS: CMOS RAM error(s) found. State = 0x%02x\n", cmos_state );
155 if (cmos_state & CS_LOST_POWER)
156 printf("IS: RTC lost power. Reset CMOS RAM with SETUP." );
157 if (cmos_state & CS_BAD_CHKSUM)
158 printf("IS: CMOS RAM checksum is bad. Run SETUP." );
159 if (cmos_state & CS_BAD_TIME)
160 printf("IS: Time invalid in CMOS RAM. Reset clock." );
161 return(EFAULT);
162 }
163
164 /* Everything seems to be OK. Read the CMOS real time clock and copy the
165 * result back to the caller.
166 */
167 if (get_cmostime(&time1, y2kflag) != 0)
168 return(EFAULT);
169 sys_datacopy(SELF, (vir_bytes) &time1,
170 who, dst_time, sizeof(struct tm));
171
172 return(OK);
173}
174
175PRIVATE int get_cmostime(struct tm *t, int y2kflag)
176{
177/* Update the structure pointed to by time with the current time as read
178 * from CMOS RAM of the RTC. If necessary, the time is converted into a
179 * binary format before being stored in the structure.
180 */
181 int osec, n;
182 unsigned long i;
183 clock_t t0,t1;
184
185 /* Start a timer to keep us from getting stuck on a dead clock. */
186 getuptime(&t0);
187 do {
188 osec = -1;
189 n = 0;
190 do {
191 getuptime(&t1);
192 if (t1-t0 > 5*HZ) {
193 printf("readclock: CMOS clock appears dead\n");
194 return(1);
195 }
196
197 /* Clock update in progress? */
198 if (read_register(RTC_REG_A) & RTC_A_UIP) continue;
199
200 t->tm_sec = read_register(RTC_SEC);
201 if (t->tm_sec != osec) {
202 /* Seconds changed. First from -1, then because the
203 * clock ticked, which is what we're waiting for to
204 * get a precise reading.
205 */
206 osec = t->tm_sec;
207 n++;
208 }
209 } while (n < 2);
210
211 /* Read the other registers. */
212 t->tm_min = read_register(RTC_MIN);
213 t->tm_hour = read_register(RTC_HOUR);
214 t->tm_mday = read_register(RTC_MDAY);
215 t->tm_mon = read_register(RTC_MONTH);
216 t->tm_year = read_register(RTC_YEAR);
217
218 /* Time stable? */
219 } while (read_register(RTC_SEC) != t->tm_sec
220 || read_register(RTC_MIN) != t->tm_min
221 || read_register(RTC_HOUR) != t->tm_hour
222 || read_register(RTC_MDAY) != t->tm_mday
223 || read_register(RTC_MONTH) != t->tm_mon
224 || read_register(RTC_YEAR) != t->tm_year);
225
226 if ((read_register(RTC_REG_B) & RTC_B_DM_BCD) == 0) {
227 /* Convert BCD to binary (default RTC mode). */
228 t->tm_year = bcd_to_dec(t->tm_year);
229 t->tm_mon = bcd_to_dec(t->tm_mon);
230 t->tm_mday = bcd_to_dec(t->tm_mday);
231 t->tm_hour = bcd_to_dec(t->tm_hour);
232 t->tm_min = bcd_to_dec(t->tm_min);
233 t->tm_sec = bcd_to_dec(t->tm_sec);
234 }
235 t->tm_mon--; /* Counts from 0. */
236
237 /* Correct the year, good until 2080. */
238 if (t->tm_year < 80) t->tm_year += 100;
239
240 if (y2kflag) {
241 /* Clock with Y2K bug, interpret 1980 as 2000, good until 2020. */
242 if (t->tm_year < 100) t->tm_year += 20;
243 }
244 return 0;
245}
246
247PRIVATE int read_register(int reg_addr)
248{
249/* Read a single CMOS register value. */
250 unsigned long r;
251 sys_outb(RTC_INDEX, reg_addr);
252 sys_inb(RTC_IO, &r);
253 return r;
254}
255
256PRIVATE int bcd_to_dec(int n)
257{
258 return ((n >> 4) & 0x0F) * 10 + (n & 0x0F);
259}
260
261PRIVATE int dec_to_bcd(int n)
262{
263 return ((n / 10) << 4) | (n % 10);
264}
265
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