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Add Exar XR68C681 support to mc68681.cpp (again) (#3755)

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* skeleton support for Exar XR68C681 dual UART device

* added support for XR68C681 MISR register

* XR68C681 extended baud rate support

Well, at least in theory. Here goes nothing!

* copyright update

* Style changes as described in mamedev pull request #3755

* More style changes for PR #3755 in mamedev

hex literals should be lower case
also some spacing corrected
This commit is contained in:
jzatarski 2018-07-22 19:51:45 -05:00 committed by Vas Crabb
parent 47e045d545
commit e6938b4226
2 changed files with 594 additions and 389 deletions
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212
src/devices/machine/mc68681.cpp
View File

@ -1,16 +1,18 @@
// license:BSD-3-Clause
// copyright-holders:Mariusz Wojcieszek, R. Belmont
// copyright-holders:Mariusz Wojcieszek, R. Belmont, Joseph Zatarski
/*
2681 DUART
68681 DUART
28C94 QUART
68340 serial module
XR68C681 DUART (backwards compatible with 68681 with some improvements)
Written by Mariusz Wojcieszek
Updated by Jonathan Gevaryahu AKA Lord Nightmare
Improved interrupt handling by R. Belmont
Rewrite and modernization in progress by R. Belmont
Addition of the duart compatible 68340 serial module support by Edstrom
Support for the Exar XR68C681 by Joseph Zatarski (July of 2018)
The main incompatibility between the 2681 and 68681 (Signetics and Motorola each
manufactured both versions of the chip) is that the 68681 has a R/W input and
@ -21,6 +23,26 @@
The command register addresses should never be read from. Doing so may place
the baud rate generator into a test mode which drives the parallel outputs with
internal counters and causes serial ports to operate at uncontrollable rates.
Exar XR68C681
The XR68C681 is an improvement upon the MC68681 which supports more baud
rates, adds an additional MISR (masked ISR) register, and adds a low-power
standby mode. There may be other differences, but these are the most
notable.
The extra baud rates are implemented by an 'X' bit for each channel. The X
bit chooses between two baud rate tables, in addition to the ACR[7] bit.
The X bit is changed by additional commands that are written to CRA and
CRB.
The MISR is a read only register that takes the place of the 'BRG Test'
register on the MC68681.
The low power standby mode is entered and left by a command written to CRA
or CRB registers. Writing the commands to either register affects the whole
DUART, not just one channel. Resetting the DUART also leaves low power
mode.
*/
#include "emu.h"
@ -41,8 +63,10 @@ static const char *const duart68681_reg_write_names[0x10] =
"MRA", "CSRA", "CRA", "THRA", "ACR", "IMR", "CRUR", "CTLR", "MRB", "CSRB", "CRB", "THRB", "IVR", "OPCR", "Set OP Bits", "Reset OP Bits"
};
static const int baud_rate_ACR_0[] = { 50, 110, 134, 200, 300, 600, 1200, 1050, 2400, 4800, 7200, 9600, 38400, 0, 0, 0 };
static const int baud_rate_ACR_1[] = { 75, 110, 134, 150, 300, 600, 1200, 2000, 2400, 4800, 1800, 9600, 19200, 0, 0, 0 };
static const int baud_rate_ACR_0[] = { 50, 110, 134, 200, 300, 600, 1200, 1050, 2400, 4800, 7200, 9600, 38400, 0, 0, 0 }; /* xr68c681 X=0 */
static const int baud_rate_ACR_0_X_1[] = { 75, 110, 134, 150, 3600, 14400, 28800, 57600, 115200, 4800, 1800, 9600, 19200, 0, 0, 0 };
static const int baud_rate_ACR_1[] = { 75, 110, 134, 150, 300, 600, 1200, 2000, 2400, 4800, 1800, 9600, 19200, 0, 0, 0 }; /* xr68c681 X=0 */
static const int baud_rate_ACR_1_X_1[] = { 50, 110, 134, 200, 3600, 14400, 28800, 57600, 115200, 4800, 7200, 9600, 38400, 0, 0, 0 };
#define INT_INPUT_PORT_CHANGE 0x80
#define INT_DELTA_BREAK_B 0x40
@ -74,6 +98,7 @@ DEFINE_DEVICE_TYPE(SCN2681, scn2681_device, "scn2681", "SCN2681 DUART")
DEFINE_DEVICE_TYPE(MC68681, mc68681_device, "mc68681", "MC68681 DUART")
DEFINE_DEVICE_TYPE(SC28C94, sc28c94_device, "sc28c94", "SC28C94 QUART")
DEFINE_DEVICE_TYPE(MC68340_DUART, mc68340_duart_device, "mc68340duart", "MC68340 DUART Device")
DEFINE_DEVICE_TYPE(XR68C681, xr68c681_device, "xr68c681", "XR68C681 DUART")
DEFINE_DEVICE_TYPE(DUART_CHANNEL, duart_channel, "duart_channel", "DUART channel")
@ -108,12 +133,17 @@ scn2681_device::scn2681_device(const machine_config &mconfig, const char *tag, d
{
}
mc68681_device::mc68681_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock)
: duart_base_device(mconfig, MC68681, tag, owner, clock),
mc68681_device::mc68681_device(const machine_config &mconfig, device_type type, const char *tag, device_t *owner, uint32_t clock)
: duart_base_device(mconfig, type, tag, owner, clock),
m_read_vector(false)
{
}
mc68681_device::mc68681_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock)
: mc68681_device(mconfig, MC68681, tag, owner, clock)
{
}
sc28c94_device::sc28c94_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock)
: duart_base_device(mconfig, SC28C94, tag, owner, clock)
{
@ -136,6 +166,15 @@ mc68340_duart_device::mc68340_duart_device(const machine_config &mconfig, const
{
}
xr68c681_device::xr68c681_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock)
: mc68681_device(mconfig, XR68C681, tag, owner, clock),
m_XTXA(false),
m_XRXA(false),
m_XTXB(false),
m_XRXB(false)
{
}
//-------------------------------------------------
// set_clocks - configuration helper to set
// the external clocks
@ -182,6 +221,16 @@ void mc68681_device::device_start()
save_item(NAME(IVR));
}
void xr68c681_device::device_start()
{
mc68681_device::device_start();
save_item(NAME(m_XTXA));
save_item(NAME(m_XRXA));
save_item(NAME(m_XTXB));
save_item(NAME(m_XRXB));
}
/*-------------------------------------------------
device reset callback
-------------------------------------------------*/
@ -209,6 +258,13 @@ void mc68681_device::device_reset()
m_read_vector = false;
}
void xr68c681_device::device_reset()
{
mc68681_device::device_reset();
m_XTXA = m_XRXA = m_XTXB = m_XRXB = false;
}
MACHINE_CONFIG_START(duart_base_device::device_add_mconfig)
MCFG_DEVICE_ADD(CHANA_TAG, DUART_CHANNEL, 0)
MCFG_DEVICE_ADD(CHANB_TAG, DUART_CHANNEL, 0)
@ -474,6 +530,17 @@ READ8_MEMBER( sc28c94_device::read )
return r;
}
READ8_MEMBER(xr68c681_device::read)
{
if (offset == 0x02)
{
LOG("Reading XR68C681 (%s) reg 0x02 (MISR)\n", tag());
return ISR & IMR;
}
else
return mc68681_device::read(space, offset, mem_mask);
}
READ8_MEMBER(duart_base_device::read)
{
uint8_t r = 0xff;
@ -624,6 +691,81 @@ WRITE8_MEMBER( sc28c94_device::write )
}
}
WRITE8_MEMBER(xr68c681_device::write)
{
if (offset == 0x02) /* CRA */
switch (data >> 4)
{
case 0x08: /* set RX extend bit */
m_XRXA = true;
m_chanA->baud_updated();
data &= 0x0f; /* disable command before we send it off to 68681 */
break;
case 0x09: /* clear RX extend bit */
m_XRXA = false;
m_chanA->baud_updated();
data &= 0x0f;
break;
case 0x0a: /* set TX extend bit */
m_XTXA = true;
m_chanA->baud_updated();
data &= 0x0f;
break;
case 0x0b: /* clear TX extend bit */
m_XTXA = false;
m_chanA->baud_updated();
data &= 0x0f;
break;
case 0x0c: /* enter low power mode TODO: unimplemented */
case 0x0d: /* leave low power mode */
case 0x0e: /* reserved */
case 0x0f: /* reserved */
data &= 0x0f;
break;
}
else if (offset == 0x0a) /* CRB */
switch (data >> 4)
{
case 0x08: /* set RX extend bit */
m_XRXB = true;
m_chanB->baud_updated();
data &= 0x0f;
break;
case 0x09: /* clear RX extend bit */
m_XRXB = false;
m_chanB->baud_updated();
data &= 0x0f;
break;
case 0x0a: /* set TX extend bit */
m_XTXB = true;
m_chanB->baud_updated();
data &= 0x0f;
break;
case 0x0b: /* clear TX extend bit */
m_XTXB = false;
m_chanB->baud_updated();
data &= 0x0f;
break;
case 0x0c: /* enter low power mode TODO: unimplemented */
case 0x0d: /* leave low power mode */
case 0x0e: /* reserved */
case 0x0f: /* reserved */
data &= 0x0f;
break;
}
mc68681_device::write(space, offset, data, mem_mask); /* pass on 68681 command */
}
WRITE8_MEMBER(duart_base_device::write)
{
offset &= 0x0f;
@ -665,8 +807,8 @@ WRITE8_MEMBER( duart_base_device::write )
if ((((IPCR>>4) & data) & 0x0f) != 0)
set_ISR_bits(INT_INPUT_PORT_CHANGE);
m_chanA->ACR_updated();
m_chanB->ACR_updated();
m_chanA->baud_updated();
m_chanB->baud_updated();
m_chanA->update_interrupts();
m_chanB->update_interrupts();
break;
@ -808,7 +950,7 @@ duart_channel *duart_base_device::get_channel(int chan)
return m_chanB;
}
int duart_base_device::calc_baud(int ch, uint8_t data)
int duart_base_device::calc_baud(int ch, bool rx, uint8_t data)
{
int baud_rate;
@ -853,6 +995,45 @@ int duart_base_device::calc_baud(int ch, uint8_t data)
return baud_rate;
}
int xr68c681_device::calc_baud(int ch, bool rx, uint8_t data)
{
int baud_rate;
baud_rate = baud_rate_ACR_0[data & 0x0f];
if (ch == 0)
{
if ((data & 0x0f) == 0x0e)
baud_rate = ip3clk/16;
else if ((data & 0x0f) == 0x0f)
baud_rate = ip3clk;
else if ((rx && m_XRXA) || (!rx && m_XTXA)) /* X = 1 */
baud_rate = BIT(ACR, 7) == 0 ? baud_rate_ACR_0_X_1[data & 0x0f] : baud_rate_ACR_1_X_1[data & 0x0f];
else /* X = 0 */
baud_rate = BIT(ACR, 7) == 0 ? baud_rate_ACR_0[data & 0x0f] : baud_rate_ACR_1[data & 0x0f];
}
else if (ch == 1)
{
if ((data & 0x0f) == 0x0e)
baud_rate = ip5clk/16;
else if ((data & 0x0f) == 0x0f)
baud_rate = ip5clk;
else if ((rx && m_XRXB) || (!rx && m_XTXB)) /* X = 1 */
baud_rate = BIT(ACR, 7) == 0 ? baud_rate_ACR_0_X_1[data & 0x0f] : baud_rate_ACR_1_X_1[data & 0x0f];
else /* X = 0 */
baud_rate = BIT(ACR, 7) == 0 ? baud_rate_ACR_0[data & 0x0f] : baud_rate_ACR_1[data & 0x0f];
}
if ((baud_rate == 0) && ((data & 0xf) != 0xd))
{
LOG("Unsupported transmitter clock: channel %d, clock select = %02x\n", ch, data);
}
//printf("%s ch %d setting baud to %d\n", tag(), ch, baud_rate);
return baud_rate;
}
void duart_base_device::clear_ISR_bits(int mask)
{
if ((ISR & mask) != 0)
@ -958,7 +1139,7 @@ void duart_channel::tra_complete()
m_uart->clear_ISR_bits(INT_TXRDYB);
// if local loopback is on, write the transmitted data as if a byte had been received
if ((MR2 & 0xC0) == 0x80)
if ((MR2 & 0xc0) == 0x80)
{
if (rx_fifo_num >= MC68681_RX_FIFO_SIZE)
{
@ -982,7 +1163,7 @@ void duart_channel::tra_complete()
void duart_channel::tra_callback()
{
// don't actually send in loopback mode
if ((MR2&0xC0) != 0x80)
if ((MR2 & 0xc0) != 0x80)
{
int bit = transmit_register_get_data_bit();
//printf("%s ch %d transmit %d\n", tag(), m_ch, bit);
@ -1032,7 +1213,7 @@ void duart_channel::update_interrupts()
}
// Handle the TxEMT and TxRDY bits based on mode
switch(MR2&0xC0) // what mode are we in?
switch (MR2 & 0xc0) // what mode are we in?
{
case 0x00: // normal mode
if (tx_enabled)
@ -1058,12 +1239,13 @@ void duart_channel::update_interrupts()
SR &= ~STATUS_TRANSMITTER_EMPTY;
}
break;
case 0xC0: // remote loopback mode
case 0xc0: // remote loopback mode
// write me, what the txrdy/txemt regs do for remote loopback mode is undocumented afaik, for now just clear both
SR &= ~STATUS_TRANSMITTER_EMPTY;
SR &= ~STATUS_TRANSMITTER_READY;
break;
}
// now handle the ISR bits
if (SR & STATUS_TRANSMITTER_READY)
{
@ -1176,8 +1358,8 @@ void duart_channel::write_chan_reg(int reg, uint8_t data)
case 0x01: /* CSR */
CSR = data;
tx_baud_rate = m_uart->calc_baud(m_ch, data & 0xf);
rx_baud_rate = m_uart->calc_baud(m_ch, (data>>4) & 0xf);
tx_baud_rate = m_uart->calc_baud(m_ch, false, data & 0xf);
rx_baud_rate = m_uart->calc_baud(m_ch, true, (data>>4) & 0xf);
//printf("%s ch %d CSR %02x Tx baud %d Rx baud %d\n", tag(), m_ch, data, tx_baud_rate, rx_baud_rate);
set_rcv_rate(rx_baud_rate);
set_tra_rate(tx_baud_rate);
@ -1371,7 +1553,7 @@ void duart_channel::write_TX(uint8_t data)
update_interrupts();
}
void duart_channel::ACR_updated()
void duart_channel::baud_updated()
{
write_chan_reg(1, CSR);
}

27
src/devices/machine/mc68681.h
View File

@ -59,7 +59,7 @@ public:
uint8_t read_rx_fifo();
void ACR_updated();
void baud_updated();
uint8_t get_chan_CSR();
@ -167,10 +167,13 @@ protected:
private:
TIMER_CALLBACK_MEMBER(duart_timer_callback);
protected:
/* registers */
uint8_t ACR; /* Auxiliary Control Register */
uint8_t IMR; /* Interrupt Mask Register */
uint8_t ISR; /* Interrupt Status Register */
private:
uint8_t OPCR; /* Output Port Conf. Register */
uint8_t OPR; /* Output Port Register */
PAIR CTR; /* Counter/Timer Preset Value */
@ -186,7 +189,7 @@ private:
double get_ct_rate();
uint16_t get_ct_count();
void start_ct(int count);
int calc_baud(int ch, uint8_t data);
virtual int calc_baud(int ch, bool rx, uint8_t data);
void clear_ISR_bits(int mask);
void set_ISR_bits(int mask);
@ -230,6 +233,7 @@ protected:
virtual void device_start() override;
virtual void device_reset() override;
virtual void update_interrupts() override;
mc68681_device(const machine_config &mconfig, device_type type, const char *tag, device_t *owner, uint32_t clock);
private:
bool m_read_vector; // if this is read and IRQ is active, it counts as pulling IACK
@ -270,10 +274,29 @@ protected:
mc68340_duart_device(const machine_config &mconfig, device_type type, const char *tag, device_t *owner, uint32_t clock);
};
class xr68c681_device : public mc68681_device
{
public:
xr68c681_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock);
virtual DECLARE_READ8_MEMBER(read) override;
virtual DECLARE_WRITE8_MEMBER(write) override;
protected:
virtual void device_start() override;
virtual void device_reset() override;
private:
virtual int calc_baud(int ch, bool rx, uint8_t data) override;
bool m_XTXA,m_XRXA,m_XTXB,m_XRXB; /* X bits for the BRG (selects between 2 BRG tables) */
};
DECLARE_DEVICE_TYPE(SCN2681, scn2681_device)
DECLARE_DEVICE_TYPE(MC68681, mc68681_device)
DECLARE_DEVICE_TYPE(SC28C94, sc28c94_device)
DECLARE_DEVICE_TYPE(MC68340_DUART, mc68340_duart_device)
DECLARE_DEVICE_TYPE(XR68C681, xr68c681_device)
DECLARE_DEVICE_TYPE(DUART_CHANNEL, duart_channel)
#endif // MAME_MACHINE_MC68681_H