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/*
* Ricoh RS5C372, R222x I2C RTC
*
* Copyright (c) 2025 Bernhard Beschow <shentey@gmail.com>
*
* Based on hw/rtc/ds1338.c
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
#include "qemu/osdep.h"
#include "hw/i2c/i2c.h"
#include "hw/qdev-properties.h"
#include "hw/resettable.h"
#include "migration/vmstate.h"
#include "qemu/bcd.h"
#include "qom/object.h"
#include "system/rtc.h"
#include "trace.h"
#define NVRAM_SIZE 0x10
/* Flags definitions */
#define SECONDS_CH 0x80
#define HOURS_PM 0x20
#define CTRL2_24 0x20
#define TYPE_RS5C372 "rs5c372"
OBJECT_DECLARE_SIMPLE_TYPE(RS5C372State, RS5C372)
struct RS5C372State {
I2CSlave parent_obj;
int64_t offset;
uint8_t wday_offset;
uint8_t nvram[NVRAM_SIZE];
uint8_t ptr;
uint8_t tx_format;
bool addr_byte;
};
static void capture_current_time(RS5C372State *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[0xf] & CTRL2_24) {
s->nvram[2] = to_bcd(now.tm_hour);
} else {
int tmp = now.tm_hour;
if (tmp % 12 == 0) {
tmp += 12;
}
if (tmp <= 12) {
s->nvram[2] = to_bcd(tmp);
} else {
s->nvram[2] = HOURS_PM | to_bcd(tmp - 12);
}
}
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(RS5C372State *s)
{
s->ptr = (s->ptr + 1) & (NVRAM_SIZE - 1);
}
static int rs5c372_event(I2CSlave *i2c, enum i2c_event event)
{
RS5C372State *s = RS5C372(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);
s->ptr = 0xf;
break;
case I2C_START_SEND:
s->addr_byte = true;
break;
default:
break;
}
return 0;
}
static uint8_t rs5c372_recv(I2CSlave *i2c)
{
RS5C372State *s = RS5C372(i2c);
uint8_t res;
res = s->nvram[s->ptr];
trace_rs5c372_recv(s->ptr, res);
inc_regptr(s);
return res;
}
static int rs5c372_send(I2CSlave *i2c, uint8_t data)
{
RS5C372State *s = RS5C372(i2c);
if (s->addr_byte) {
s->ptr = data >> 4;
s->tx_format = data & 0xf;
s->addr_byte = false;
return 0;
}
trace_rs5c372_send(s->ptr, data);
if (s->ptr < 7) {
/* Time register. */
struct tm now;
qemu_get_timedate(&now, s->offset);
switch (s->ptr) {
case 0:
now.tm_sec = from_bcd(data & 0x7f);
break;
case 1:
now.tm_min = from_bcd(data & 0x7f);
break;
case 2:
if (s->nvram[0xf] & CTRL2_24) {
now.tm_hour = from_bcd(data & 0x3f);
} else {
int tmp = from_bcd(data & (HOURS_PM - 1));
if (data & HOURS_PM) {
tmp += 12;
}
if (tmp % 12 == 0) {
tmp -= 12;
}
now.tm_hour = tmp;
}
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 {
s->nvram[s->ptr] = data;
}
inc_regptr(s);
return 0;
}
static void rs5c372_reset_hold(Object *obj, ResetType type)
{
RS5C372State *s = RS5C372(obj);
/* 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 const VMStateDescription rs5c372_vmstate = {
.name = "rs5c372",
.version_id = 1,
.minimum_version_id = 1,
.fields = (const VMStateField[]) {
VMSTATE_I2C_SLAVE(parent_obj, RS5C372State),
VMSTATE_INT64(offset, RS5C372State),
VMSTATE_UINT8_V(wday_offset, RS5C372State, 2),
VMSTATE_UINT8_ARRAY(nvram, RS5C372State, NVRAM_SIZE),
VMSTATE_UINT8(ptr, RS5C372State),
VMSTATE_UINT8(tx_format, RS5C372State),
VMSTATE_BOOL(addr_byte, RS5C372State),
VMSTATE_END_OF_LIST()
}
};
static void rs5c372_init(Object *obj)
{
qdev_prop_set_uint8(DEVICE(obj), "address", 0x32);
}
static void rs5c372_class_init(ObjectClass *klass, void *data)
{
DeviceClass *dc = DEVICE_CLASS(klass);
I2CSlaveClass *k = I2C_SLAVE_CLASS(klass);
ResettableClass *rc = RESETTABLE_CLASS(klass);
k->event = rs5c372_event;
k->recv = rs5c372_recv;
k->send = rs5c372_send;
dc->vmsd = &rs5c372_vmstate;
rc->phases.hold = rs5c372_reset_hold;
}
static const TypeInfo rs5c372_types[] = {
{
.name = TYPE_RS5C372,
.parent = TYPE_I2C_SLAVE,
.instance_size = sizeof(RS5C372State),
.instance_init = rs5c372_init,
.class_init = rs5c372_class_init,
},
};
DEFINE_TYPES(rs5c372_types)
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