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 licenced under the GNU GPL v2.
   8  */
   9
  10 #include "i2c.h"
  11
  12 typedef struct {
  13     i2c_slave i2c;
  14     time_t offset;
  15     struct tm now;
  16     uint8_t nvram[56];
  17     int ptr;
  18     int addr_byte;
  19 } DS1338State;
  20
  21 static void ds1338_event(i2c_slave *i2c, enum i2c_event event)
  22 {
  23     DS1338State *s = FROM_I2C_SLAVE(DS1338State, i2c);
  24
  25     switch (event) {
  26     case I2C_START_RECV:
  27         qemu_get_timedate(&s->now, s->offset);
  28         s->nvram[0] = to_bcd(s->now.tm_sec);
  29         s->nvram[1] = to_bcd(s->now.tm_min);
  30         if (s->nvram[2] & 0x40) {
  31             s->nvram[2] = (to_bcd((s->now.tm_hour % 12)) + 1) | 0x40;
  32             if (s->now.tm_hour >= 12) {
  33                 s->nvram[2] |= 0x20;
  34             }
  35         } else {
  36             s->nvram[2] = to_bcd(s->now.tm_hour);
  37         }
  38         s->nvram[3] = to_bcd(s->now.tm_wday) + 1;
  39         s->nvram[4] = to_bcd(s->now.tm_mday);
  40         s->nvram[5] = to_bcd(s->now.tm_mon) + 1;
  41         s->nvram[6] = to_bcd(s->now.tm_year - 100);
  42         break;
  43     case I2C_START_SEND:
  44         s->addr_byte = 1;
  45         break;
  46     default:
  47         break;
  48     }
  49 }
  50
  51 static int ds1338_recv(i2c_slave *i2c)
  52 {
  53     DS1338State *s = FROM_I2C_SLAVE(DS1338State, i2c);
  54     uint8_t res;
  55
  56     res  = s->nvram[s->ptr];
  57     s->ptr = (s->ptr + 1) & 0xff;
  58     return res;
  59 }
  60
  61 static int ds1338_send(i2c_slave *i2c, uint8_t data)
  62 {
  63     DS1338State *s = FROM_I2C_SLAVE(DS1338State, i2c);
  64     if (s->addr_byte) {
  65         s->ptr = data;
  66         s->addr_byte = 0;
  67         return 0;
  68     }
  69     s->nvram[s->ptr - 8] = data;
  70     if (data < 8) {
  71         qemu_get_timedate(&s->now, s->offset);
  72         switch(data) {
  73         case 0:
  74             /* TODO: Implement CH (stop) bit.  */
  75             s->now.tm_sec = from_bcd(data & 0x7f);
  76             break;
  77         case 1:
  78             s->now.tm_min = from_bcd(data & 0x7f);
  79             break;
  80         case 2:
  81             if (data & 0x40) {
  82                 if (data & 0x20) {
  83                     data = from_bcd(data & 0x4f) + 11;
  84                 } else {
  85                     data = from_bcd(data & 0x1f) - 1;
  86                 }
  87             } else {
  88                 data = from_bcd(data);
  89             }
  90             s->now.tm_hour = data;
  91             break;
  92         case 3:
  93             s->now.tm_wday = from_bcd(data & 7) - 1;
  94             break;
  95         case 4:
  96             s->now.tm_mday = from_bcd(data & 0x3f);
  97             break;
  98         case 5:
  99             s->now.tm_mon = from_bcd(data & 0x1f) - 1;
 100         case 6:
 101             s->now.tm_year = from_bcd(data) + 100;
 102             break;
 103         case 7:
 104             /* Control register. Currently ignored.  */
 105             break;
 106         }
 107         s->offset = qemu_timedate_diff(&s->now);
 108     }
 109     s->ptr = (s->ptr + 1) & 0xff;
 110     return 0;
 111 }
 112
 113 static int ds1338_init(i2c_slave *i2c)
 114 {
 115     return 0;
 116 }
 117
 118 static I2CSlaveInfo ds1338_info = {
 119     .qdev.name = "ds1338",
 120     .qdev.size = sizeof(DS1338State),
 121     .init = ds1338_init,
 122     .event = ds1338_event,
 123     .recv = ds1338_recv,
 124     .send = ds1338_send,
 125 };
 126
 127 static void ds1338_register_devices(void)
 128 {
 129     i2c_register_slave(&ds1338_info);
 130 }
 131
 132 device_init(ds1338_register_devices)