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/*
* 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 "hw/i2c/i2c.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"
#define DS1338(obj) OBJECT_CHECK(DS1338State, (obj), TYPE_DS1338)
typedef struct DS1338State {
I2CSlave parent_obj;
int64_t offset;
uint8_t wday_offset;
uint8_t nvram[NVRAM_SIZE];
int32_t ptr;
bool addr_byte;
} DS1338State;
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 void 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;
}
}
static int 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 int ds1338_init(I2CSlave *i2c)
{
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->init = ds1338_init;
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)
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