hw/ds1338.c

   1 /*
   2  * MAXIM DS1338 I2C RTC+NVRAM
   3  *
   4  * Copyright (c) 2009 CodeSourcery.
   5  * Written by Paul Brook
   6  *
   7  * This code is licensed under the GNU GPL v2.
   8  *
   9  * Contributions after 2012-01-13 are licensed under the terms of the
  10  * GNU GPL, version 2 or (at your option) any later version.
  11  */
  12
  13 #include "i2c.h"
  14
  15 typedef struct {
  16     I2CSlave i2c;
  17     time_t offset;
  18     struct tm now;
  19     uint8_t nvram[56];
  20     int ptr;
  21     int addr_byte;
  22 } DS1338State;
  23
  24 static void ds1338_event(I2CSlave *i2c, enum i2c_event event)
  25 {
  26     DS1338State *s = FROM_I2C_SLAVE(DS1338State, i2c);
  27
  28     switch (event) {
  29     case I2C_START_RECV:
  30         qemu_get_timedate(&s->now, s->offset);
  31         s->nvram[0] = to_bcd(s->now.tm_sec);
  32         s->nvram[1] = to_bcd(s->now.tm_min);
  33         if (s->nvram[2] & 0x40) {
  34             s->nvram[2] = (to_bcd((s->now.tm_hour % 12)) + 1) | 0x40;
  35             if (s->now.tm_hour >= 12) {
  36                 s->nvram[2] |= 0x20;
  37             }
  38         } else {
  39             s->nvram[2] = to_bcd(s->now.tm_hour);
  40         }
  41         s->nvram[3] = to_bcd(s->now.tm_wday) + 1;
  42         s->nvram[4] = to_bcd(s->now.tm_mday);
  43         s->nvram[5] = to_bcd(s->now.tm_mon) + 1;
  44         s->nvram[6] = to_bcd(s->now.tm_year - 100);
  45         break;
  46     case I2C_START_SEND:
  47         s->addr_byte = 1;
  48         break;
  49     default:
  50         break;
  51     }
  52 }
  53
  54 static int ds1338_recv(I2CSlave *i2c)
  55 {
  56     DS1338State *s = FROM_I2C_SLAVE(DS1338State, i2c);
  57     uint8_t res;
  58
  59     res  = s->nvram[s->ptr];
  60     s->ptr = (s->ptr + 1) & 0xff;
  61     return res;
  62 }
  63
  64 static int ds1338_send(I2CSlave *i2c, uint8_t data)
  65 {
  66     DS1338State *s = FROM_I2C_SLAVE(DS1338State, i2c);
  67     if (s->addr_byte) {
  68         s->ptr = data;
  69         s->addr_byte = 0;
  70         return 0;
  71     }
  72     s->nvram[s->ptr - 8] = data;
  73     if (data < 8) {
  74         qemu_get_timedate(&s->now, s->offset);
  75         switch(data) {
  76         case 0:
  77             /* TODO: Implement CH (stop) bit.  */
  78             s->now.tm_sec = from_bcd(data & 0x7f);
  79             break;
  80         case 1:
  81             s->now.tm_min = from_bcd(data & 0x7f);
  82             break;
  83         case 2:
  84             if (data & 0x40) {
  85                 if (data & 0x20) {
  86                     data = from_bcd(data & 0x4f) + 11;
  87                 } else {
  88                     data = from_bcd(data & 0x1f) - 1;
  89                 }
  90             } else {
  91                 data = from_bcd(data);
  92             }
  93             s->now.tm_hour = data;
  94             break;
  95         case 3:
  96             s->now.tm_wday = from_bcd(data & 7) - 1;
  97             break;
  98         case 4:
  99             s->now.tm_mday = from_bcd(data & 0x3f);
 100             break;
 101         case 5:
 102             s->now.tm_mon = from_bcd(data & 0x1f) - 1;
 103         case 6:
 104             s->now.tm_year = from_bcd(data) + 100;
 105             break;
 106         case 7:
 107             /* Control register. Currently ignored.  */
 108             break;
 109         }
 110         s->offset = qemu_timedate_diff(&s->now);
 111     }
 112     s->ptr = (s->ptr + 1) & 0xff;
 113     return 0;
 114 }
 115
 116 static int ds1338_init(I2CSlave *i2c)
 117 {
 118     return 0;
 119 }
 120
 121 static void ds1338_class_init(ObjectClass *klass, void *data)
 122 {
 123     I2CSlaveClass *k = I2C_SLAVE_CLASS(klass);
 124
 125     k->init = ds1338_init;
 126     k->event = ds1338_event;
 127     k->recv = ds1338_recv;
 128     k->send = ds1338_send;
 129 }
 130
 131 static DeviceInfo ds1338_info = {
 132     .name = "ds1338",
 133     .size = sizeof(DS1338State),
 134     .class_init = ds1338_class_init,
 135 };
 136
 137 static void ds1338_register_devices(void)
 138 {
 139     i2c_register_slave(&ds1338_info);
 140 }
 141
 142 device_init(ds1338_register_devices)