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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 "i2c.h"
/* Size of NVRAM including both the user-accessible area and the
* secondary register area.
*/
#define NVRAM_SIZE 64
typedef struct {
I2CSlave i2c;
time_t offset;
uint8_t nvram[NVRAM_SIZE];
int ptr;
int addr_byte;
} DS1338State;
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] & 0x40) {
s->nvram[2] = (to_bcd((now.tm_hour % 12)) + 1) | 0x40;
if (now.tm_hour >= 12) {
s->nvram[2] |= 0x20;
}
} else {
s->nvram[2] = to_bcd(now.tm_hour);
}
s->nvram[3] = to_bcd(now.tm_wday) + 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 = FROM_I2C_SLAVE(DS1338State, 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 = 1;
break;
default:
break;
}
}
static int ds1338_recv(I2CSlave *i2c)
{
DS1338State *s = FROM_I2C_SLAVE(DS1338State, 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 = FROM_I2C_SLAVE(DS1338State, i2c);
if (s->addr_byte) {
s->ptr = data & (NVRAM_SIZE - 1);
s->addr_byte = 0;
return 0;
}
if (s->ptr < 8) {
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 & 0x40) {
if (data & 0x20) {
data = from_bcd(data & 0x4f) + 11;
} else {
data = from_bcd(data & 0x1f) - 1;
}
} else {
data = from_bcd(data);
}
now.tm_hour = data;
break;
case 3:
now.tm_wday = from_bcd(data & 7) - 1;
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;
case 7:
/* Control register. Currently ignored. */
break;
}
s->offset = qemu_timedate_diff(&now);
} else {
s->nvram[s->ptr] = data;
}
inc_regptr(s);
return 0;
}
static int ds1338_init(I2CSlave *i2c)
{
return 0;
}
static void ds1338_class_init(ObjectClass *klass, void *data)
{
I2CSlaveClass *k = I2C_SLAVE_CLASS(klass);
k->init = ds1338_init;
k->event = ds1338_event;
k->recv = ds1338_recv;
k->send = ds1338_send;
}
static TypeInfo ds1338_info = {
.name = "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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