arch/mips/sibyte/swarm/time.c

   1 /*
   2  * Copyright (C) 2000, 2001 Broadcom Corporation
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License
   6  * as published by the Free Software Foundation; either version 2
   7  * of the License, or (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  17  */
  18
  19 /*
  20  * Time routines for the swarm board.  We pass all the hard stuff
  21  * through to the sb1250 handling code.  Only thing we really keep
  22  * track of here is what time of day we think it is.  And we don't
  23  * really even do a good job of that...
  24  */
  25
  26
  27 #include <linux/bcd.h>
  28 #include <linux/init.h>
  29 #include <linux/time.h>
  30 #include <linux/sched.h>
  31 #include <linux/spinlock.h>
  32 #include <asm/system.h>
  33 #include <asm/addrspace.h>
  34 #include <asm/io.h>
  35
  36 #include <asm/sibyte/sb1250.h>
  37 #include <asm/sibyte/sb1250_regs.h>
  38 #include <asm/sibyte/sb1250_smbus.h>
  39
  40 static unsigned long long sec_bias = 0;
  41 static unsigned int usec_bias = 0;
  42
  43 /* Xicor 1241 definitions */
  44
  45 /*
  46  * Register bits
  47  */
  48
  49 #define X1241REG_SR_BAT 0x80            /* currently on battery power */
  50 #define X1241REG_SR_RWEL 0x04           /* r/w latch is enabled, can write RTC */
  51 #define X1241REG_SR_WEL 0x02            /* r/w latch is unlocked, can enable r/w now */
  52 #define X1241REG_SR_RTCF 0x01           /* clock failed */
  53 #define X1241REG_BL_BP2 0x80            /* block protect 2 */
  54 #define X1241REG_BL_BP1 0x40            /* block protect 1 */
  55 #define X1241REG_BL_BP0 0x20            /* block protect 0 */
  56 #define X1241REG_BL_WD1 0x10
  57 #define X1241REG_BL_WD0 0x08
  58 #define X1241REG_HR_MIL 0x80            /* military time format */
  59
  60 /*
  61  * Register numbers
  62  */
  63
  64 #define X1241REG_BL     0x10            /* block protect bits */
  65 #define X1241REG_INT    0x11            /*  */
  66 #define X1241REG_SC     0x30            /* Seconds */
  67 #define X1241REG_MN     0x31            /* Minutes */
  68 #define X1241REG_HR     0x32            /* Hours */
  69 #define X1241REG_DT     0x33            /* Day of month */
  70 #define X1241REG_MO     0x34            /* Month */
  71 #define X1241REG_YR     0x35            /* Year */
  72 #define X1241REG_DW     0x36            /* Day of Week */
  73 #define X1241REG_Y2K    0x37            /* Year 2K */
  74 #define X1241REG_SR     0x3F            /* Status register */
  75
  76 #define X1241_CCR_ADDRESS       0x6F
  77
  78 #define SMB_CSR(reg) (IOADDR(A_SMB_REGISTER(1, reg)))
  79
  80 static int xicor_read(uint8_t addr)
  81 {
  82         while (bus_readq(SMB_CSR(R_SMB_STATUS)) & M_SMB_BUSY)
  83                 ;
  84
  85         bus_writeq((addr >> 8) & 0x7, SMB_CSR(R_SMB_CMD));
  86         bus_writeq((addr & 0xff), SMB_CSR(R_SMB_DATA));
  87         bus_writeq((V_SMB_ADDR(X1241_CCR_ADDRESS) | V_SMB_TT_WR2BYTE),
  88                    SMB_CSR(R_SMB_START));
  89
  90         while (bus_readq(SMB_CSR(R_SMB_STATUS)) & M_SMB_BUSY)
  91                 ;
  92
  93         bus_writeq((V_SMB_ADDR(X1241_CCR_ADDRESS) | V_SMB_TT_RD1BYTE),
  94                    SMB_CSR(R_SMB_START));
  95
  96         while (bus_readq(SMB_CSR(R_SMB_STATUS)) & M_SMB_BUSY)
  97                 ;
  98
  99         if (bus_readq(SMB_CSR(R_SMB_STATUS)) & M_SMB_ERROR) {
 100                 /* Clear error bit by writing a 1 */
 101                 bus_writeq(M_SMB_ERROR, SMB_CSR(R_SMB_STATUS));
 102                 return -1;
 103         }
 104
 105         return (bus_readq(SMB_CSR(R_SMB_DATA)) & 0xff);
 106 }
 107
 108 static int xicor_write(uint8_t addr, int b)
 109 {
 110         while (bus_readq(SMB_CSR(R_SMB_STATUS)) & M_SMB_BUSY)
 111                 ;
 112
 113         bus_writeq(addr, SMB_CSR(R_SMB_CMD));
 114         bus_writeq((addr & 0xff) | ((b & 0xff) << 8), SMB_CSR(R_SMB_DATA));
 115         bus_writeq(V_SMB_ADDR(X1241_CCR_ADDRESS) | V_SMB_TT_WR3BYTE,
 116                    SMB_CSR(R_SMB_START));
 117
 118         while (bus_readq(SMB_CSR(R_SMB_STATUS)) & M_SMB_BUSY)
 119                 ;
 120
 121         if (bus_readq(SMB_CSR(R_SMB_STATUS)) & M_SMB_ERROR) {
 122                 /* Clear error bit by writing a 1 */
 123                 bus_writeq(M_SMB_ERROR, SMB_CSR(R_SMB_STATUS));
 124                 return -1;
 125         } else {
 126                 return 0;
 127         }
 128 }
 129
 130 /*
 131  * In order to set the CMOS clock precisely, set_rtc_mmss has to be
 132  * called 500 ms after the second nowtime has started, because when
 133  * nowtime is written into the registers of the CMOS clock, it will
 134  * jump to the next second precisely 500 ms later. Check the Motorola
 135  * MC146818A or Dallas DS12887 data sheet for details.
 136  *
 137  * BUG: This routine does not handle hour overflow properly; it just
 138  *      sets the minutes. Usually you'll only notice that after reboot!
 139  */
 140 int set_rtc_mmss(unsigned long nowtime)
 141 {
 142         int retval = 0;
 143         int real_seconds, real_minutes, cmos_minutes;
 144
 145         cmos_minutes = xicor_read(X1241REG_MN);
 146         cmos_minutes = BCD2BIN(cmos_minutes);
 147
 148         /*
 149          * since we're only adjusting minutes and seconds,
 150          * don't interfere with hour overflow. This avoids
 151          * messing with unknown time zones but requires your
 152          * RTC not to be off by more than 15 minutes
 153          */
 154         real_seconds = nowtime % 60;
 155         real_minutes = nowtime / 60;
 156         if (((abs(real_minutes - cmos_minutes) + 15)/30) & 1)
 157                 real_minutes += 30;             /* correct for half hour time zone */
 158         real_minutes %= 60;
 159
 160         /* unlock writes to the CCR */
 161         xicor_write(X1241REG_SR, X1241REG_SR_WEL);
 162         xicor_write(X1241REG_SR, X1241REG_SR_WEL | X1241REG_SR_RWEL);
 163
 164         if (abs(real_minutes - cmos_minutes) < 30) {
 165                 real_seconds = BIN2BCD(real_seconds);
 166                 real_minutes = BIN2BCD(real_minutes);
 167                 xicor_write(X1241REG_SC, real_seconds);
 168                 xicor_write(X1241REG_MN, real_minutes);
 169         } else {
 170                 printk(KERN_WARNING
 171                        "set_rtc_mmss: can't update from %d to %d\n",
 172                        cmos_minutes, real_minutes);
 173                 retval = -1;
 174         }
 175
 176         xicor_write(X1241REG_SR, 0);
 177
 178         printk("set_rtc_mmss: %02d:%02d\n", real_minutes, real_seconds);
 179
 180         return retval;
 181 }
 182
 183 static unsigned long __init get_swarm_time(void)
 184 {
 185         unsigned int year, mon, day, hour, min, sec, y2k;
 186
 187         sec = xicor_read(X1241REG_SC);
 188         min = xicor_read(X1241REG_MN);
 189         hour = xicor_read(X1241REG_HR);
 190
 191         if (hour & X1241REG_HR_MIL) {
 192                 hour &= 0x3f;
 193         } else {
 194                 if (hour & 0x20)
 195                         hour = (hour & 0xf) + 0x12;
 196         }
 197
 198         sec = BCD2BIN(sec);
 199         min = BCD2BIN(min);
 200         hour = BCD2BIN(hour);
 201
 202         day = xicor_read(X1241REG_DT);
 203         mon = xicor_read(X1241REG_MO);
 204         year = xicor_read(X1241REG_YR);
 205         y2k = xicor_read(X1241REG_Y2K);
 206
 207         day = BCD2BIN(day);
 208         mon = BCD2BIN(mon);
 209         year = BCD2BIN(year);
 210         y2k = BCD2BIN(y2k);
 211
 212         year += (y2k * 100);
 213
 214         return mktime(year, mon, day, hour, min, sec);
 215 }
 216
 217 /*
 218  *  Bring up the timer at 100 Hz.
 219  */
 220 void __init swarm_time_init(void)
 221 {
 222         unsigned int flags;
 223         int status;
 224
 225         /* Set up the scd general purpose timer 0 to cpu 0 */
 226         sb1250_time_init();
 227
 228         /* Establish communication with the Xicor 1241 RTC */
 229         /* XXXKW how do I share the SMBus with the I2C subsystem? */
 230
 231         bus_writeq(K_SMB_FREQ_400KHZ, SMB_CSR(R_SMB_FREQ));
 232         bus_writeq(0, SMB_CSR(R_SMB_CONTROL));
 233
 234         if ((status = xicor_read(X1241REG_SR_RTCF)) < 0) {
 235                 printk("x1241: couldn't detect on SWARM SMBus 1\n");
 236         } else {
 237                 if (status & X1241REG_SR_RTCF)
 238                         printk("x1241: battery failed -- time is probably wrong\n");
 239                 write_seqlock_irqsave(&xtime_lock, flags);
 240                 xtime.tv_sec = get_swarm_time();
 241                 xtime.tv_nsec = 0;
 242                 write_sequnlock_irqrestore(&xtime_lock, flags);
 243         }
 244 }