arch/mips/sibyte/swarm/rtc_m41t81.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Copyright (C) 2000, 2001 Broadcom Corporation
   4  *
   5  * Copyright (C) 2002 MontaVista Software Inc.
   6  * Author: jsun@mvista.com or jsun@junsun.net
   7  */
   8 #include <linux/bcd.h>
   9 #include <linux/types.h>
  10 #include <linux/time.h>
  11
  12 #include <asm/time.h>
  13 #include <asm/addrspace.h>
  14 #include <asm/io.h>
  15
  16 #include <asm/sibyte/sb1250.h>
  17 #include <asm/sibyte/sb1250_regs.h>
  18 #include <asm/sibyte/sb1250_smbus.h>
  19
  20
  21 /* M41T81 definitions */
  22
  23 /*
  24  * Register bits
  25  */
  26
  27 #define M41T81REG_SC_ST         0x80            /* stop bit */
  28 #define M41T81REG_HR_CB         0x40            /* century bit */
  29 #define M41T81REG_HR_CEB        0x80            /* century enable bit */
  30 #define M41T81REG_CTL_S         0x20            /* sign bit */
  31 #define M41T81REG_CTL_FT        0x40            /* frequency test bit */
  32 #define M41T81REG_CTL_OUT       0x80            /* output level */
  33 #define M41T81REG_WD_RB0        0x01            /* watchdog resolution bit 0 */
  34 #define M41T81REG_WD_RB1        0x02            /* watchdog resolution bit 1 */
  35 #define M41T81REG_WD_BMB0       0x04            /* watchdog multiplier bit 0 */
  36 #define M41T81REG_WD_BMB1       0x08            /* watchdog multiplier bit 1 */
  37 #define M41T81REG_WD_BMB2       0x10            /* watchdog multiplier bit 2 */
  38 #define M41T81REG_WD_BMB3       0x20            /* watchdog multiplier bit 3 */
  39 #define M41T81REG_WD_BMB4       0x40            /* watchdog multiplier bit 4 */
  40 #define M41T81REG_AMO_ABE       0x20            /* alarm in "battery back-up mode" enable bit */
  41 #define M41T81REG_AMO_SQWE      0x40            /* square wave enable */
  42 #define M41T81REG_AMO_AFE       0x80            /* alarm flag enable flag */
  43 #define M41T81REG_ADT_RPT5      0x40            /* alarm repeat mode bit 5 */
  44 #define M41T81REG_ADT_RPT4      0x80            /* alarm repeat mode bit 4 */
  45 #define M41T81REG_AHR_RPT3      0x80            /* alarm repeat mode bit 3 */
  46 #define M41T81REG_AHR_HT        0x40            /* halt update bit */
  47 #define M41T81REG_AMN_RPT2      0x80            /* alarm repeat mode bit 2 */
  48 #define M41T81REG_ASC_RPT1      0x80            /* alarm repeat mode bit 1 */
  49 #define M41T81REG_FLG_AF        0x40            /* alarm flag (read only) */
  50 #define M41T81REG_FLG_WDF       0x80            /* watchdog flag (read only) */
  51 #define M41T81REG_SQW_RS0       0x10            /* sqw frequency bit 0 */
  52 #define M41T81REG_SQW_RS1       0x20            /* sqw frequency bit 1 */
  53 #define M41T81REG_SQW_RS2       0x40            /* sqw frequency bit 2 */
  54 #define M41T81REG_SQW_RS3       0x80            /* sqw frequency bit 3 */
  55
  56
  57 /*
  58  * Register numbers
  59  */
  60
  61 #define M41T81REG_TSC   0x00            /* tenths/hundredths of second */
  62 #define M41T81REG_SC    0x01            /* seconds */
  63 #define M41T81REG_MN    0x02            /* minute */
  64 #define M41T81REG_HR    0x03            /* hour/century */
  65 #define M41T81REG_DY    0x04            /* day of week */
  66 #define M41T81REG_DT    0x05            /* date of month */
  67 #define M41T81REG_MO    0x06            /* month */
  68 #define M41T81REG_YR    0x07            /* year */
  69 #define M41T81REG_CTL   0x08            /* control */
  70 #define M41T81REG_WD    0x09            /* watchdog */
  71 #define M41T81REG_AMO   0x0A            /* alarm: month */
  72 #define M41T81REG_ADT   0x0B            /* alarm: date */
  73 #define M41T81REG_AHR   0x0C            /* alarm: hour */
  74 #define M41T81REG_AMN   0x0D            /* alarm: minute */
  75 #define M41T81REG_ASC   0x0E            /* alarm: second */
  76 #define M41T81REG_FLG   0x0F            /* flags */
  77 #define M41T81REG_SQW   0x13            /* square wave register */
  78
  79 #define M41T81_CCR_ADDRESS      0x68
  80
  81 #define SMB_CSR(reg)    IOADDR(A_SMB_REGISTER(1, reg))
  82
  83 static int m41t81_read(uint8_t addr)
  84 {
  85         while (__raw_readq(SMB_CSR(R_SMB_STATUS)) & M_SMB_BUSY)
  86                 ;
  87
  88         __raw_writeq(addr & 0xff, SMB_CSR(R_SMB_CMD));
  89         __raw_writeq(V_SMB_ADDR(M41T81_CCR_ADDRESS) | V_SMB_TT_WR1BYTE,
  90                      SMB_CSR(R_SMB_START));
  91
  92         while (__raw_readq(SMB_CSR(R_SMB_STATUS)) & M_SMB_BUSY)
  93                 ;
  94
  95         __raw_writeq(V_SMB_ADDR(M41T81_CCR_ADDRESS) | V_SMB_TT_RD1BYTE,
  96                      SMB_CSR(R_SMB_START));
  97
  98         while (__raw_readq(SMB_CSR(R_SMB_STATUS)) & M_SMB_BUSY)
  99                 ;
 100
 101         if (__raw_readq(SMB_CSR(R_SMB_STATUS)) & M_SMB_ERROR) {
 102                 /* Clear error bit by writing a 1 */
 103                 __raw_writeq(M_SMB_ERROR, SMB_CSR(R_SMB_STATUS));
 104                 return -1;
 105         }
 106
 107         return __raw_readq(SMB_CSR(R_SMB_DATA)) & 0xff;
 108 }
 109
 110 static int m41t81_write(uint8_t addr, int b)
 111 {
 112         while (__raw_readq(SMB_CSR(R_SMB_STATUS)) & M_SMB_BUSY)
 113                 ;
 114
 115         __raw_writeq(addr & 0xff, SMB_CSR(R_SMB_CMD));
 116         __raw_writeq(b & 0xff, SMB_CSR(R_SMB_DATA));
 117         __raw_writeq(V_SMB_ADDR(M41T81_CCR_ADDRESS) | V_SMB_TT_WR2BYTE,
 118                      SMB_CSR(R_SMB_START));
 119
 120         while (__raw_readq(SMB_CSR(R_SMB_STATUS)) & M_SMB_BUSY)
 121                 ;
 122
 123         if (__raw_readq(SMB_CSR(R_SMB_STATUS)) & M_SMB_ERROR) {
 124                 /* Clear error bit by writing a 1 */
 125                 __raw_writeq(M_SMB_ERROR, SMB_CSR(R_SMB_STATUS));
 126                 return -1;
 127         }
 128
 129         /* read the same byte again to make sure it is written */
 130         __raw_writeq(V_SMB_ADDR(M41T81_CCR_ADDRESS) | V_SMB_TT_RD1BYTE,
 131                      SMB_CSR(R_SMB_START));
 132
 133         while (__raw_readq(SMB_CSR(R_SMB_STATUS)) & M_SMB_BUSY)
 134                 ;
 135
 136         return 0;
 137 }
 138
 139 int m41t81_set_time(time64_t t)
 140 {
 141         struct rtc_time tm;
 142         unsigned long flags;
 143
 144         /* Note we don't care about the century */
 145         rtc_time64_to_tm(t, &tm);
 146
 147         /*
 148          * Note the write order matters as it ensures the correctness.
 149          * When we write sec, 10th sec is clear.  It is reasonable to
 150          * believe we should finish writing min within a second.
 151          */
 152
 153         spin_lock_irqsave(&rtc_lock, flags);
 154         tm.tm_sec = bin2bcd(tm.tm_sec);
 155         m41t81_write(M41T81REG_SC, tm.tm_sec);
 156
 157         tm.tm_min = bin2bcd(tm.tm_min);
 158         m41t81_write(M41T81REG_MN, tm.tm_min);
 159
 160         tm.tm_hour = bin2bcd(tm.tm_hour);
 161         tm.tm_hour = (tm.tm_hour & 0x3f) | (m41t81_read(M41T81REG_HR) & 0xc0);
 162         m41t81_write(M41T81REG_HR, tm.tm_hour);
 163
 164         /* tm_wday starts from 0 to 6 */
 165         if (tm.tm_wday == 0) tm.tm_wday = 7;
 166         tm.tm_wday = bin2bcd(tm.tm_wday);
 167         m41t81_write(M41T81REG_DY, tm.tm_wday);
 168
 169         tm.tm_mday = bin2bcd(tm.tm_mday);
 170         m41t81_write(M41T81REG_DT, tm.tm_mday);
 171
 172         /* tm_mon starts from 0, *ick* */
 173         tm.tm_mon ++;
 174         tm.tm_mon = bin2bcd(tm.tm_mon);
 175         m41t81_write(M41T81REG_MO, tm.tm_mon);
 176
 177         /* we don't do century, everything is beyond 2000 */
 178         tm.tm_year %= 100;
 179         tm.tm_year = bin2bcd(tm.tm_year);
 180         m41t81_write(M41T81REG_YR, tm.tm_year);
 181         spin_unlock_irqrestore(&rtc_lock, flags);
 182
 183         return 0;
 184 }
 185
 186 time64_t m41t81_get_time(void)
 187 {
 188         unsigned int year, mon, day, hour, min, sec;
 189         unsigned long flags;
 190
 191         /*
 192          * min is valid if two reads of sec are the same.
 193          */
 194         for (;;) {
 195                 spin_lock_irqsave(&rtc_lock, flags);
 196                 sec = m41t81_read(M41T81REG_SC);
 197                 min = m41t81_read(M41T81REG_MN);
 198                 if (sec == m41t81_read(M41T81REG_SC)) break;
 199                 spin_unlock_irqrestore(&rtc_lock, flags);
 200         }
 201         hour = m41t81_read(M41T81REG_HR) & 0x3f;
 202         day = m41t81_read(M41T81REG_DT);
 203         mon = m41t81_read(M41T81REG_MO);
 204         year = m41t81_read(M41T81REG_YR);
 205         spin_unlock_irqrestore(&rtc_lock, flags);
 206
 207         sec = bcd2bin(sec);
 208         min = bcd2bin(min);
 209         hour = bcd2bin(hour);
 210         day = bcd2bin(day);
 211         mon = bcd2bin(mon);
 212         year = bcd2bin(year);
 213
 214         year += 2000;
 215
 216         return mktime64(year, mon, day, hour, min, sec);
 217 }
 218
 219 int m41t81_probe(void)
 220 {
 221         unsigned int tmp;
 222
 223         /* enable chip if it is not enabled yet */
 224         tmp = m41t81_read(M41T81REG_SC);
 225         m41t81_write(M41T81REG_SC, tmp & 0x7f);
 226
 227         return m41t81_read(M41T81REG_SC) != -1;
 228 }