qemu

ds1338.c (6348B)

---

 /*
  * MAXIM DS1338 I2C RTC+NVRAM
  *
  * Copyright (c) 2009 CodeSourcery.
  * Written by Paul Brook
  *
  * This code is licensed under the GNU GPL v2.
  *
  * Contributions after 2012-01-13 are licensed under the terms of the
  * GNU GPL, version 2 or (at your option) any later version.
  */
 
 #include "qemu/osdep.h"
 #include "hw/i2c/i2c.h"
 #include "migration/vmstate.h"
 #include "qemu/bcd.h"
 #include "qemu/module.h"
 #include "qom/object.h"
 #include "sysemu/rtc.h"
 
 /* Size of NVRAM including both the user-accessible area and the
  * secondary register area.
  */
 #define NVRAM_SIZE 64
 
 /* Flags definitions */
 #define SECONDS_CH 0x80
 #define HOURS_12   0x40
 #define HOURS_PM   0x20
 #define CTRL_OSF   0x20
 
 #define TYPE_DS1338 "ds1338"
 OBJECT_DECLARE_SIMPLE_TYPE(DS1338State, DS1338)
 
 struct DS1338State {
     I2CSlave parent_obj;
 
     int64_t offset;
     uint8_t wday_offset;
     uint8_t nvram[NVRAM_SIZE];
     int32_t ptr;
     bool addr_byte;
 };
 
 static const VMStateDescription vmstate_ds1338 = {
     .name = "ds1338",
     .version_id = 2,
     .minimum_version_id = 1,
     .fields = (VMStateField[]) {
         VMSTATE_I2C_SLAVE(parent_obj, DS1338State),
         VMSTATE_INT64(offset, DS1338State),
         VMSTATE_UINT8_V(wday_offset, DS1338State, 2),
         VMSTATE_UINT8_ARRAY(nvram, DS1338State, NVRAM_SIZE),
         VMSTATE_INT32(ptr, DS1338State),
         VMSTATE_BOOL(addr_byte, DS1338State),
         VMSTATE_END_OF_LIST()
     }
 };
 
 static void capture_current_time(DS1338State *s)
 {
     /* Capture the current time into the secondary registers
      * which will be actually read by the data transfer operation.
      */
     struct tm now;
     qemu_get_timedate(&now, s->offset);
     s->nvram[0] = to_bcd(now.tm_sec);
     s->nvram[1] = to_bcd(now.tm_min);
     if (s->nvram[2] & HOURS_12) {
         int tmp = now.tm_hour;
         if (tmp % 12 == 0) {
             tmp += 12;
         }
         if (tmp <= 12) {
             s->nvram[2] = HOURS_12 | to_bcd(tmp);
         } else {
             s->nvram[2] = HOURS_12 | HOURS_PM | to_bcd(tmp - 12);
         }
     } else {
         s->nvram[2] = to_bcd(now.tm_hour);
     }
     s->nvram[3] = (now.tm_wday + s->wday_offset) % 7 + 1;
     s->nvram[4] = to_bcd(now.tm_mday);
     s->nvram[5] = to_bcd(now.tm_mon + 1);
     s->nvram[6] = to_bcd(now.tm_year - 100);
 }
 
 static void inc_regptr(DS1338State *s)
 {
     /* The register pointer wraps around after 0x3F; wraparound
      * causes the current time/date to be retransferred into
      * the secondary registers.
      */
     s->ptr = (s->ptr + 1) & (NVRAM_SIZE - 1);
     if (!s->ptr) {
         capture_current_time(s);
     }
 }
 
 static int ds1338_event(I2CSlave *i2c, enum i2c_event event)
 {
     DS1338State *s = DS1338(i2c);
 
     switch (event) {
     case I2C_START_RECV:
         /* In h/w, capture happens on any START condition, not just a
          * START_RECV, but there is no need to actually capture on
          * START_SEND, because the guest can't get at that data
          * without going through a START_RECV which would overwrite it.
          */
         capture_current_time(s);
         break;
     case I2C_START_SEND:
         s->addr_byte = true;
         break;
     default:
         break;
     }
 
     return 0;
 }
 
 static uint8_t ds1338_recv(I2CSlave *i2c)
 {
     DS1338State *s = DS1338(i2c);
     uint8_t res;
 
     res  = s->nvram[s->ptr];
     inc_regptr(s);
     return res;
 }
 
 static int ds1338_send(I2CSlave *i2c, uint8_t data)
 {
     DS1338State *s = DS1338(i2c);
 
     if (s->addr_byte) {
         s->ptr = data & (NVRAM_SIZE - 1);
         s->addr_byte = false;
         return 0;
     }
     if (s->ptr < 7) {
         /* Time register. */
         struct tm now;
         qemu_get_timedate(&now, s->offset);
         switch(s->ptr) {
         case 0:
             /* TODO: Implement CH (stop) bit.  */
             now.tm_sec = from_bcd(data & 0x7f);
             break;
         case 1:
             now.tm_min = from_bcd(data & 0x7f);
             break;
         case 2:
             if (data & HOURS_12) {
                 int tmp = from_bcd(data & (HOURS_PM - 1));
                 if (data & HOURS_PM) {
                     tmp += 12;
                 }
                 if (tmp % 12 == 0) {
                     tmp -= 12;
                 }
                 now.tm_hour = tmp;
             } else {
                 now.tm_hour = from_bcd(data & (HOURS_12 - 1));
             }
             break;
         case 3:
             {
                 /* The day field is supposed to contain a value in
                    the range 1-7. Otherwise behavior is undefined.
                  */
                 int user_wday = (data & 7) - 1;
                 s->wday_offset = (user_wday - now.tm_wday + 7) % 7;
             }
             break;
         case 4:
             now.tm_mday = from_bcd(data & 0x3f);
             break;
         case 5:
             now.tm_mon = from_bcd(data & 0x1f) - 1;
             break;
         case 6:
             now.tm_year = from_bcd(data) + 100;
             break;
         }
         s->offset = qemu_timedate_diff(&now);
     } else if (s->ptr == 7) {
         /* Control register. */
 
         /* Ensure bits 2, 3 and 6 will read back as zero. */
         data &= 0xB3;
 
         /* Attempting to write the OSF flag to logic 1 leaves the
            value unchanged. */
         data = (data & ~CTRL_OSF) | (data & s->nvram[s->ptr] & CTRL_OSF);
 
         s->nvram[s->ptr] = data;
     } else {
         s->nvram[s->ptr] = data;
     }
     inc_regptr(s);
     return 0;
 }
 
 static void ds1338_reset(DeviceState *dev)
 {
     DS1338State *s = DS1338(dev);
 
     /* The clock is running and synchronized with the host */
     s->offset = 0;
     s->wday_offset = 0;
     memset(s->nvram, 0, NVRAM_SIZE);
     s->ptr = 0;
     s->addr_byte = false;
 }
 
 static void ds1338_class_init(ObjectClass *klass, void *data)
 {
     DeviceClass *dc = DEVICE_CLASS(klass);
     I2CSlaveClass *k = I2C_SLAVE_CLASS(klass);
 
     k->event = ds1338_event;
     k->recv = ds1338_recv;
     k->send = ds1338_send;
     dc->reset = ds1338_reset;
     dc->vmsd = &vmstate_ds1338;
 }
 
 static const TypeInfo ds1338_info = {
     .name          = TYPE_DS1338,
     .parent        = TYPE_I2C_SLAVE,
     .instance_size = sizeof(DS1338State),
     .class_init    = ds1338_class_init,
 };
 
 static void ds1338_register_types(void)
 {
     type_register_static(&ds1338_info);
 }
 
 type_init(ds1338_register_types)