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 /* Size of NVRAM including both the user-accessible area and the
  16  * secondary register area.
  17  */
  18 #define NVRAM_SIZE 64
  19
  20 typedef struct {
  21     I2CSlave i2c;
  22     int64_t offset;
  23     uint8_t nvram[NVRAM_SIZE];
  24     int32_t ptr;
  25     bool addr_byte;
  26 } DS1338State;
  27
  28 static const VMStateDescription vmstate_ds1338 = {
  29     .name = "ds1338",
  30     .version_id = 1,
  31     .minimum_version_id = 1,
  32     .minimum_version_id_old = 1,
  33     .fields = (VMStateField[]) {
  34         VMSTATE_I2C_SLAVE(i2c, DS1338State),
  35         VMSTATE_INT64(offset, DS1338State),
  36         VMSTATE_UINT8_ARRAY(nvram, DS1338State, NVRAM_SIZE),
  37         VMSTATE_INT32(ptr, DS1338State),
  38         VMSTATE_BOOL(addr_byte, DS1338State),
  39         VMSTATE_END_OF_LIST()
  40     }
  41 };
  42
  43 static void capture_current_time(DS1338State *s)
  44 {
  45     /* Capture the current time into the secondary registers
  46      * which will be actually read by the data transfer operation.
  47      */
  48     struct tm now;
  49     qemu_get_timedate(&now, s->offset);
  50     s->nvram[0] = to_bcd(now.tm_sec);
  51     s->nvram[1] = to_bcd(now.tm_min);
  52     if (s->nvram[2] & 0x40) {
  53         s->nvram[2] = (to_bcd((now.tm_hour % 12)) + 1) | 0x40;
  54         if (now.tm_hour >= 12) {
  55             s->nvram[2] |= 0x20;
  56         }
  57     } else {
  58         s->nvram[2] = to_bcd(now.tm_hour);
  59     }
  60     s->nvram[3] = to_bcd(now.tm_wday) + 1;
  61     s->nvram[4] = to_bcd(now.tm_mday);
  62     s->nvram[5] = to_bcd(now.tm_mon) + 1;
  63     s->nvram[6] = to_bcd(now.tm_year - 100);
  64 }
  65
  66 static void inc_regptr(DS1338State *s)
  67 {
  68     /* The register pointer wraps around after 0x3F; wraparound
  69      * causes the current time/date to be retransferred into
  70      * the secondary registers.
  71      */
  72     s->ptr = (s->ptr + 1) & (NVRAM_SIZE - 1);
  73     if (!s->ptr) {
  74         capture_current_time(s);
  75     }
  76 }
  77
  78 static void ds1338_event(I2CSlave *i2c, enum i2c_event event)
  79 {
  80     DS1338State *s = FROM_I2C_SLAVE(DS1338State, i2c);
  81
  82     switch (event) {
  83     case I2C_START_RECV:
  84         /* In h/w, capture happens on any START condition, not just a
  85          * START_RECV, but there is no need to actually capture on
  86          * START_SEND, because the guest can't get at that data
  87          * without going through a START_RECV which would overwrite it.
  88          */
  89         capture_current_time(s);
  90         break;
  91     case I2C_START_SEND:
  92         s->addr_byte = true;
  93         break;
  94     default:
  95         break;
  96     }
  97 }
  98
  99 static int ds1338_recv(I2CSlave *i2c)
 100 {
 101     DS1338State *s = FROM_I2C_SLAVE(DS1338State, i2c);
 102     uint8_t res;
 103
 104     res  = s->nvram[s->ptr];
 105     inc_regptr(s);
 106     return res;
 107 }
 108
 109 static int ds1338_send(I2CSlave *i2c, uint8_t data)
 110 {
 111     DS1338State *s = FROM_I2C_SLAVE(DS1338State, i2c);
 112     if (s->addr_byte) {
 113         s->ptr = data & (NVRAM_SIZE - 1);
 114         s->addr_byte = false;
 115         return 0;
 116     }
 117     if (s->ptr < 8) {
 118         struct tm now;
 119         qemu_get_timedate(&now, s->offset);
 120         switch(s->ptr) {
 121         case 0:
 122             /* TODO: Implement CH (stop) bit.  */
 123             now.tm_sec = from_bcd(data & 0x7f);
 124             break;
 125         case 1:
 126             now.tm_min = from_bcd(data & 0x7f);
 127             break;
 128         case 2:
 129             if (data & 0x40) {
 130                 if (data & 0x20) {
 131                     data = from_bcd(data & 0x4f) + 11;
 132                 } else {
 133                     data = from_bcd(data & 0x1f) - 1;
 134                 }
 135             } else {
 136                 data = from_bcd(data);
 137             }
 138             now.tm_hour = data;
 139             break;
 140         case 3:
 141             now.tm_wday = from_bcd(data & 7) - 1;
 142             break;
 143         case 4:
 144             now.tm_mday = from_bcd(data & 0x3f);
 145             break;
 146         case 5:
 147             now.tm_mon = from_bcd(data & 0x1f) - 1;
 148             break;
 149         case 6:
 150             now.tm_year = from_bcd(data) + 100;
 151             break;
 152         case 7:
 153             /* Control register. Currently ignored.  */
 154             break;
 155         }
 156         s->offset = qemu_timedate_diff(&now);
 157     } else {
 158         s->nvram[s->ptr] = data;
 159     }
 160     inc_regptr(s);
 161     return 0;
 162 }
 163
 164 static int ds1338_init(I2CSlave *i2c)
 165 {
 166     return 0;
 167 }
 168
 169 static void ds1338_class_init(ObjectClass *klass, void *data)
 170 {
 171     DeviceClass *dc = DEVICE_CLASS(klass);
 172     I2CSlaveClass *k = I2C_SLAVE_CLASS(klass);
 173
 174     k->init = ds1338_init;
 175     k->event = ds1338_event;
 176     k->recv = ds1338_recv;
 177     k->send = ds1338_send;
 178     dc->vmsd = &vmstate_ds1338;
 179 }
 180
 181 static TypeInfo ds1338_info = {
 182     .name          = "ds1338",
 183     .parent        = TYPE_I2C_SLAVE,
 184     .instance_size = sizeof(DS1338State),
 185     .class_init    = ds1338_class_init,
 186 };
 187
 188 static void ds1338_register_types(void)
 189 {
 190     type_register_static(&ds1338_info);
 191 }
 192
 193 type_init(ds1338_register_types)