arch/mips/lasat/ds1603.c

   1 /*
   2  * Dallas Semiconductors 1603 RTC driver
   3  *
   4  * Brian Murphy <brian@murphy.dk>
   5  *
   6  */
   7 #include <linux/kernel.h>
   8 #include <asm/lasat/lasat.h>
   9 #include <linux/delay.h>
  10 #include <asm/lasat/ds1603.h>
  11 #include <asm/time.h>
  12
  13 #include "ds1603.h"
  14
  15 #define READ_TIME_CMD 0x81
  16 #define SET_TIME_CMD 0x80
  17 #define TRIMMER_SET_CMD 0xC0
  18 #define TRIMMER_VALUE_MASK 0x38
  19 #define TRIMMER_SHIFT 3
  20
  21 struct ds_defs *ds1603 = NULL;
  22
  23 /* HW specific register functions */
  24 static void rtc_reg_write(unsigned long val)
  25 {
  26         *ds1603->reg = val;
  27 }
  28
  29 static unsigned long rtc_reg_read(void)
  30 {
  31         unsigned long tmp = *ds1603->reg;
  32         return tmp;
  33 }
  34
  35 static unsigned long rtc_datareg_read(void)
  36 {
  37         unsigned long tmp = *ds1603->data_reg;
  38         return tmp;
  39 }
  40
  41 static void rtc_nrst_high(void)
  42 {
  43         rtc_reg_write(rtc_reg_read() | ds1603->rst);
  44 }
  45
  46 static void rtc_nrst_low(void)
  47 {
  48         rtc_reg_write(rtc_reg_read() & ~ds1603->rst);
  49 }
  50
  51 static void rtc_cycle_clock(unsigned long data)
  52 {
  53         data |= ds1603->clk;
  54         rtc_reg_write(data);
  55         lasat_ndelay(250);
  56         if (ds1603->data_reversed)
  57                 data &= ~ds1603->data;
  58         else
  59                 data |= ds1603->data;
  60         data &= ~ds1603->clk;
  61         rtc_reg_write(data);
  62         lasat_ndelay(250 + ds1603->huge_delay);
  63 }
  64
  65 static void rtc_write_databit(unsigned int bit)
  66 {
  67         unsigned long data = rtc_reg_read();
  68         if (ds1603->data_reversed)
  69                 bit = !bit;
  70         if (bit)
  71                 data |= ds1603->data;
  72         else
  73                 data &= ~ds1603->data;
  74
  75         rtc_reg_write(data);
  76         lasat_ndelay(50 + ds1603->huge_delay);
  77         rtc_cycle_clock(data);
  78 }
  79
  80 static unsigned int rtc_read_databit(void)
  81 {
  82         unsigned int data;
  83
  84         data = (rtc_datareg_read() & (1 << ds1603->data_read_shift))
  85                 >> ds1603->data_read_shift;
  86         rtc_cycle_clock(rtc_reg_read());
  87         return data;
  88 }
  89
  90 static void rtc_write_byte(unsigned int byte)
  91 {
  92         int i;
  93
  94         for (i = 0; i<=7; i++) {
  95                 rtc_write_databit(byte & 1L);
  96                 byte >>= 1;
  97         }
  98 }
  99
 100 static void rtc_write_word(unsigned long word)
 101 {
 102         int i;
 103
 104         for (i = 0; i<=31; i++) {
 105                 rtc_write_databit(word & 1L);
 106                 word >>= 1;
 107         }
 108 }
 109
 110 static unsigned long rtc_read_word(void)
 111 {
 112         int i;
 113         unsigned long word = 0;
 114         unsigned long shift = 0;
 115
 116         for (i = 0; i<=31; i++) {
 117                 word |= rtc_read_databit() << shift;
 118                 shift++;
 119         }
 120         return word;
 121 }
 122
 123 static void rtc_init_op(void)
 124 {
 125         rtc_nrst_high();
 126
 127         rtc_reg_write(rtc_reg_read() & ~ds1603->clk);
 128
 129         lasat_ndelay(50);
 130 }
 131
 132 static void rtc_end_op(void)
 133 {
 134         rtc_nrst_low();
 135         lasat_ndelay(1000);
 136 }
 137
 138 /* interface */
 139 unsigned long ds1603_read(void)
 140 {
 141         unsigned long word;
 142         unsigned long flags;
 143
 144         spin_lock_irqsave(&rtc_lock, flags);
 145         rtc_init_op();
 146         rtc_write_byte(READ_TIME_CMD);
 147         word = rtc_read_word();
 148         rtc_end_op();
 149         spin_unlock_irqrestore(&rtc_lock, flags);
 150         return word;
 151 }
 152
 153 int ds1603_set(unsigned long time)
 154 {
 155         unsigned long flags;
 156
 157         spin_lock_irqsave(&rtc_lock, flags);
 158         rtc_init_op();
 159         rtc_write_byte(SET_TIME_CMD);
 160         rtc_write_word(time);
 161         rtc_end_op();
 162         spin_unlock_irqrestore(&rtc_lock, flags);
 163
 164         return 0;
 165 }
 166
 167 void ds1603_set_trimmer(unsigned int trimval)
 168 {
 169         rtc_init_op();
 170         rtc_write_byte(((trimval << TRIMMER_SHIFT) & TRIMMER_VALUE_MASK)
 171                         | (TRIMMER_SET_CMD));
 172         rtc_end_op();
 173 }
 174
 175 void ds1603_disable(void)
 176 {
 177         ds1603_set_trimmer(TRIMMER_DISABLE_RTC);
 178 }
 179
 180 void ds1603_enable(void)
 181 {
 182         ds1603_set_trimmer(TRIMMER_DEFAULT);
 183 }