// license:BSD-3-Clause
// copyright-holders:Nathan Woods
/***************************************************************************
MSM6242 / Epson RTC 62421 / 62423 Real Time Clock
TODO:
- Stop timer callbacks on every single tick
- HOLD mechanism
- IRQs are grossly mapped
- STOP / RESET mechanism
- why skns.c games try to read uninitialized registers?
***************************************************************************/
#include "emu.h"
#include "machine/msm6242.h"
//**************************************************************************
// CONSTANTS
//**************************************************************************
enum
{
MSM6242_REG_S1 = 0,
MSM6242_REG_S10,
MSM6242_REG_MI1,
MSM6242_REG_MI10,
MSM6242_REG_H1,
MSM6242_REG_H10,
MSM6242_REG_D1,
MSM6242_REG_D10,
MSM6242_REG_MO1,
MSM6242_REG_MO10,
MSM6242_REG_Y1,
MSM6242_REG_Y10,
MSM6242_REG_W,
MSM6242_REG_CD,
MSM6242_REG_CE,
MSM6242_REG_CF
};
#define TIMER_RTC_CALLBACK 1
#define LOG_UNMAPPED 0
#define LOG_IRQ 0
#define LOG_IRQ_ENABLE 0
//**************************************************************************
// GLOBAL VARIABLES
//**************************************************************************
// device type definition
const device_type MSM6242 = &device_creator<msm6242_device>;
//**************************************************************************
// LIVE DEVICE
//**************************************************************************
//-------------------------------------------------
// msm6242_device - constructor
//-------------------------------------------------
msm6242_device::msm6242_device(const machine_config &mconfig, std::string tag, device_t *owner, UINT32 clock)
: device_t(mconfig, MSM6242, "MSM6242 RTC", tag, owner, clock, "msm6242", __FILE__),
device_rtc_interface(mconfig, *this),
m_out_int_handler(*this)
{
}
//-------------------------------------------------
// device_start - device-specific startup
//-------------------------------------------------
void msm6242_device::device_start()
{
m_out_int_handler.resolve();
// let's call the timer callback every tick
m_timer = timer_alloc(TIMER_RTC_CALLBACK);
m_timer->adjust(attotime::zero);
// get real time from system
set_current_time(machine());
// set up registers
m_tick = 0;
m_irq_flag = 0;
m_irq_type = 0;
// TODO: skns writes 0x4 to D then expects E == 6 and F == 4, perhaps those are actually saved in the RTC CMOS?
m_reg[0] = 0;
m_reg[1] = 0x6;
m_reg[2] = 0x4;
// save states
save_item(NAME(m_reg));
save_item(NAME(m_irq_flag));
save_item(NAME(m_irq_type));
save_item(NAME(m_tick));
save_item(NAME(m_last_update_time));
}
//-------------------------------------------------
// device_reset - device-specific reset
//-------------------------------------------------
void msm6242_device::device_reset()
{
if (!m_out_int_handler.isnull())
m_out_int_handler(CLEAR_LINE);
}
//-------------------------------------------------
// device_pre_save - called prior to saving the
// state, so that registered variables can be
// properly normalized
//-------------------------------------------------
void msm6242_device::device_pre_save()
{
// update the RTC registers so that we can get the right values
update_rtc_registers();
}
//-------------------------------------------------
// device_post_load - called after the loading a
// saved state, so that registered variables can
// be expaneded as necessary
//-------------------------------------------------
void msm6242_device::device_post_load()
{
// this is probably redundant, because the timer state is saved; but it isn't
// a terribly bad idea
update_timer();
}
//-------------------------------------------------
// device_timer - called whenever a device timer
// fires
//-------------------------------------------------
void msm6242_device::device_timer(emu_timer &timer, device_timer_id id, int param, void *ptr)
{
switch(id)
{
case TIMER_RTC_CALLBACK:
rtc_timer_callback();
break;
}
}
//-------------------------------------------------
// irq
//-------------------------------------------------
void msm6242_device::irq(UINT8 irq_type)
{
// are we actually raising this particular IRQ?
if (m_irq_flag == 1 && m_irq_type == irq_type)
{
// log if appropriate
if (LOG_IRQ)
logerror("%s: MSM6242 logging IRQ #%d\n", machine().describe_context(), (int) irq_type);
// ...and assert the output line
if (!m_out_int_handler.isnull())
m_out_int_handler(ASSERT_LINE);
}
}
//-------------------------------------------------
// bump
//-------------------------------------------------
UINT64 msm6242_device::bump(int rtc_register, UINT64 delta, UINT64 register_min, UINT64 register_range)
{
UINT64 carry = 0;
if (delta > 0)
{
// get the register value
UINT64 register_value = (rtc_register == RTC_TICKS)
? m_tick
: get_clock_register(rtc_register);
// increment the value
UINT64 new_register_value = ((register_value - register_min + delta) % register_range) + register_min;
// calculate the cary
carry = ((register_value - register_min) + delta) / register_range;
// store the new register value
if (rtc_register == RTC_TICKS)
m_tick = (UINT16) new_register_value;
else
set_clock_register(rtc_register, (int) new_register_value);
}
return carry;
}
//-------------------------------------------------
// current_time
//-------------------------------------------------
UINT64 msm6242_device::current_time()
{
return machine().time().as_ticks(clock());
}
//-------------------------------------------------
// update_rtc_registers
//-------------------------------------------------
void msm6242_device::update_rtc_registers()
{
// get the absolute current time, in ticks
UINT64 curtime = current_time();
// how long as it been since we last updated?
UINT64 delta = curtime - m_last_update_time;
// set current time
m_last_update_time = curtime;
// no delta? just return
if (delta == 0)
return;
// ticks
if ((m_tick % 200) != (int)((delta + m_tick) % 0x200))
irq(IRQ_64THSECOND);
delta = bump(RTC_TICKS, delta, 0, 0x8000);
if (delta == 0)
return;
// seconds
irq(IRQ_SECOND);
delta = bump(RTC_SECOND, delta, 0, 60);
if (delta == 0)
return;
// minutes
irq(IRQ_MINUTE);
delta = bump(RTC_MINUTE, delta, 0, 60);
if (delta == 0)
return;
// hours
irq(IRQ_HOUR);
delta = bump(RTC_HOUR, delta, 0, 24);
if (delta == 0)
return;
// days
while(delta--)
advance_days();
}
//-------------------------------------------------
// update_timer
//-------------------------------------------------
void msm6242_device::update_timer()
{
UINT64 callback_ticks = 0;
attotime callback_time = attotime::never;
// we only need to call back if the IRQ flag is on, and we have a handler
if (!m_out_int_handler.isnull() && m_irq_flag == 1)
{
switch(m_irq_type)
{
case IRQ_HOUR:
callback_ticks += (59 - get_clock_register(RTC_MINUTE)) * (0x8000 * 60);
// fall through
case IRQ_MINUTE:
callback_ticks += (59 - get_clock_register(RTC_SECOND)) * 0x8000;
// fall through
case IRQ_SECOND:
callback_ticks += 0x8000 - m_tick;
break;
case IRQ_64THSECOND:
callback_ticks += 0x200 - (m_tick % 0x200);
break;
}
}
// if set, convert ticks to an attotime
if (callback_ticks > 0)
{
// get the current time
UINT64 curtime = current_time();
// we need the absolute callback time, in ticks
UINT64 absolute_callback_ticks = curtime + callback_ticks;
// convert that to an attotime
attotime absolute_callback_time = attotime::from_ticks(absolute_callback_ticks, clock());
// and finally get the delta as an attotime
callback_time = absolute_callback_time - machine().time();
}
m_timer->adjust(callback_time);
}
//-------------------------------------------------
// rtc_clock_updated
//-------------------------------------------------
void msm6242_device::rtc_clock_updated(int year, int month, int day, int day_of_week, int hour, int minute, int second)
{
m_last_update_time = current_time();
}
//-------------------------------------------------
// rtc_timer_callback
//-------------------------------------------------
void msm6242_device::rtc_timer_callback()
{
update_rtc_registers();
update_timer();
}
//-------------------------------------------------
// get_clock_nibble
//-------------------------------------------------
UINT8 msm6242_device::get_clock_nibble(int rtc_register, bool high)
{
int value = get_clock_register(rtc_register);
value /= high ? 10 : 1;
return (UINT8) ((value % 10) & 0x0F);
}
//-------------------------------------------------
// get_clock_nibble
//-------------------------------------------------
const char *msm6242_device::irq_type_string(UINT8 irq_type)
{
switch(irq_type)
{
case IRQ_64THSECOND: return "1/64th second";
case IRQ_SECOND: return "second";
case IRQ_MINUTE: return "minute";
case IRQ_HOUR: return "hour";
default: return "???";
}
}
//**************************************************************************
// READ/WRITE HANDLERS
//**************************************************************************
//-------------------------------------------------
// read
//-------------------------------------------------
READ8_MEMBER( msm6242_device::read )
{
int hour, pm;
UINT8 result;
// update the registers; they may have changed
update_rtc_registers();
switch(offset)
{
case MSM6242_REG_S1:
result = get_clock_nibble(RTC_SECOND, false);
break;
case MSM6242_REG_S10:
result = get_clock_nibble(RTC_SECOND, true);
break;
case MSM6242_REG_MI1:
result = get_clock_nibble(RTC_MINUTE, false);
break;
case MSM6242_REG_MI10:
result = get_clock_nibble(RTC_MINUTE, true);
break;
case MSM6242_REG_H1:
case MSM6242_REG_H10:
pm = 0;
hour = get_clock_register(RTC_HOUR);
// check for 12/24 hour mode
if ((m_reg[2] & 0x04) == 0) // 12 hour mode?
{
if (hour >= 12)
pm = 1;
hour %= 12;
if ( hour == 0 )
hour = 12;
}
if ( offset == MSM6242_REG_H1 )
result = hour % 10;
else
result = (hour / 10) | (pm <<2);
break;
case MSM6242_REG_D1:
result = get_clock_nibble(RTC_DAY, false);
break;
case MSM6242_REG_D10:
result = get_clock_nibble(RTC_DAY, true);
break;
case MSM6242_REG_MO1:
result = get_clock_nibble(RTC_MONTH, false);
break;
case MSM6242_REG_MO10:
result = get_clock_nibble(RTC_MONTH, true);
break;
case MSM6242_REG_Y1:
result = get_clock_nibble(RTC_YEAR, false);
break;
case MSM6242_REG_Y10:
result = get_clock_nibble(RTC_YEAR, true);
break;
case MSM6242_REG_W:
result = (UINT8) (get_clock_register(RTC_DAY_OF_WEEK) - 1);
break;
case MSM6242_REG_CD:
case MSM6242_REG_CE:
case MSM6242_REG_CF:
result = m_reg[offset - MSM6242_REG_CD];
break;
default:
result = 0x00;
if (LOG_UNMAPPED)
logerror("%s: MSM6242 unmapped offset %02x read\n", machine().describe_context(), offset);
break;
}
return result;
}
//-------------------------------------------------
// write
//-------------------------------------------------
WRITE8_MEMBER( msm6242_device::write )
{
switch(offset)
{
case MSM6242_REG_CD:
// x--- 30s ADJ
// -x-- IRQ FLAG
// --x- BUSY
// ---x HOLD
m_reg[0] = data & 0x0f;
break;
case MSM6242_REG_CE:
// xx-- t0,t1 (timing irq)
// --x- STD
// ---x MASK
m_reg[1] = data & 0x0f;
if((data & 3) == 0) // MASK & STD = 0
{
m_irq_flag = 1;
m_irq_type = (data & 0xc) >> 2;
if (LOG_IRQ_ENABLE)
logerror("%s: MSM6242 enabling irq '%s'\n", machine().describe_context(), irq_type_string(m_irq_type));
}
else
{
m_irq_flag = 0;
if ( !m_out_int_handler.isnull() )
m_out_int_handler( CLEAR_LINE );
if (LOG_IRQ_ENABLE)
logerror("%s: MSM6242 disabling irq\n", machine().describe_context());
}
break;
case MSM6242_REG_CF:
// x--- TEST
// -x-- 24/12
// --x- STOP
// ---x RESET
// the 12/24 mode bit can only be changed when RESET does a 1 -> 0 transition
if (((data & 0x01) == 0x00) && (m_reg[2] & 0x01))
m_reg[2] = (m_reg[2] & ~0x04) | (data & 0x04);
else
m_reg[2] = (data & 0x0b) | (m_reg[2] & 4);
break;
default:
if (LOG_UNMAPPED)
logerror("%s: MSM6242 unmapped offset %02x written with %02x\n", machine().describe_context(), offset, data);
break;
}
// update the timer variable in response to potential changes
update_timer();
}