/*
DingusPPC - The Experimental PowerPC Macintosh emulator
Copyright (C) 2018-23 divingkatae and maximum
(theweirdo) spatium
(Contact divingkatae#1017 or powermax#2286 on Discord for more info)
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see .
*/
/** @file MESH (Macintosh Enhanced SCSI Hardware) controller emulation. */
#include
#include
#include
#include
#include
#include
#include
using namespace MeshScsi;
int MeshController::device_postinit()
{
this->bus_obj = dynamic_cast(gMachineObj->get_comp_by_name("Scsi0"));
this->int_ctrl = dynamic_cast(
gMachineObj->get_comp_by_type(HWCompType::INT_CTRL));
this->irq_id = this->int_ctrl->register_dev_int(IntSrc::SCSI1);
return 0;
}
void MeshController::reset(bool is_hard_reset)
{
this->cur_cmd = SeqCmd::NoOperation;
this->fifo_cnt = 0;
this->int_mask = 0;
this->xfer_count = 0;
if (is_hard_reset) {
this->bus_stat = 0;
this->sync_params = (0 << 16) | 2; // fast async operation (guessed)
}
}
uint8_t MeshController::read(uint8_t reg_offset)
{
switch(reg_offset) {
case MeshReg::XferCount0:
return this->xfer_count & 0xFFU;
case MeshReg::XferCount1:
return (this->xfer_count >> 8) & 0xFFU;
case MeshReg::Sequence:
return this->cur_cmd;
case MeshReg::BusStatus0:
return this->bus_obj->test_ctrl_lines(0xFFU);
case MeshReg::BusStatus1:
return this->bus_obj->test_ctrl_lines(0xE000U) >> 8;
case MeshReg::FIFOCount:
return this->fifo_cnt;
case MeshReg::Exception:
return 0;
case MeshReg::Error:
return 0;
case MeshReg::IntMask:
return this->int_mask;
case MeshReg::Interrupt:
return this->int_stat;
case MeshReg::DestID:
return this->dst_id;
case MeshReg::SyncParms:
return this->sync_params;
case MeshReg::MeshID:
return this->chip_id; // tell them who we are
default:
LOG_F(WARNING, "MESH: read from unimplemented register at offset 0x%x", reg_offset);
}
return 0;
}
void MeshController::write(uint8_t reg_offset, uint8_t value)
{
uint16_t new_stat;
switch(reg_offset) {
case MeshReg::Sequence:
perform_command(value);
break;
case MeshReg::BusStatus1:
new_stat = value << 8;
if (new_stat != this->bus_stat) {
for (uint16_t mask = SCSI_CTRL_RST; mask >= SCSI_CTRL_SEL; mask >>= 1) {
if ((new_stat ^ this->bus_stat) & mask) {
if (new_stat & mask)
this->bus_obj->assert_ctrl_line(new_stat, mask);
else
this->bus_obj->release_ctrl_line(new_stat, mask);
}
}
this->bus_stat = new_stat;
}
break;
case MeshReg::IntMask:
this->int_mask = value;
break;
case MeshReg::Interrupt:
this->int_stat &= ~(value & INT_MASK); // clear requested interrupt bits
update_irq();
break;
case MeshReg::SourceID:
this->src_id = value;
break;
case MeshReg::DestID:
this->dst_id = value;
break;
case MeshReg::SyncParms:
this->sync_params = value;
break;
case MeshReg::SelTimeOut:
LOG_F(9, "MESH: selection timeout set to 0x%x", value);
break;
default:
LOG_F(WARNING, "MESH: write to unimplemented register at offset 0x%x",
reg_offset);
}
}
void MeshController::perform_command(const uint8_t cmd)
{
this->cur_cmd = cmd;
this->int_stat &= ~INT_CMD_DONE;
switch (this->cur_cmd & 0xF) {
case SeqCmd::Arbitrate:
this->bus_obj->release_ctrl_lines(this->src_id);
this->cur_state = SeqState::BUS_FREE;
this->sequencer();
break;
case SeqCmd::Select:
this->cur_state = SeqState::SEL_BEGIN;
this->sequencer();
break;
case SeqCmd::DisReselect:
LOG_F(9, "MESH: DisReselect command requested");
this->int_stat |= INT_CMD_DONE;
break;
case SeqCmd::ResetMesh:
this->reset(false);
this->int_stat |= INT_CMD_DONE;
break;
case SeqCmd::FlushFIFO:
LOG_F(INFO, "MESH: FlushFIFO command requested");
break;
default:
LOG_F(ERROR, "MESH: unsupported sequencer command 0x%X", this->cur_cmd);
}
}
void MeshController::seq_defer_state(uint64_t delay_ns)
{
seq_timer_id = TimerManager::get_instance()->add_oneshot_timer(
delay_ns,
[this]() {
// re-enter the sequencer with the state specified in next_state
this->cur_state = this->next_state;
this->sequencer();
});
}
void MeshController::sequencer()
{
switch (this->cur_state) {
case SeqState::IDLE:
break;
case SeqState::BUS_FREE:
if (this->bus_obj->current_phase() == ScsiPhase::BUS_FREE) {
this->next_state = SeqState::ARB_BEGIN;
this->seq_defer_state(BUS_FREE_DELAY + BUS_SETTLE_DELAY);
} else { // continue waiting
this->next_state = SeqState::BUS_FREE;
this->seq_defer_state(BUS_FREE_DELAY);
}
break;
case SeqState::ARB_BEGIN:
if (!this->bus_obj->begin_arbitration(this->src_id)) {
LOG_F(ERROR, "MESH: arbitration error, bus not free!");
this->bus_obj->release_ctrl_lines(this->src_id);
this->next_state = SeqState::BUS_FREE;
this->seq_defer_state(BUS_CLEAR_DELAY);
break;
}
this->next_state = SeqState::ARB_END;
this->seq_defer_state(ARB_DELAY);
break;
case SeqState::ARB_END:
if (this->bus_obj->end_arbitration(this->src_id) &&
!this->bus_obj->test_ctrl_lines(SCSI_CTRL_SEL)) { // arbitration won
this->bus_obj->assert_ctrl_line(this->src_id, SCSI_CTRL_SEL);
} else { // arbitration lost
LOG_F(INFO, "MESH: arbitration lost!");
this->bus_obj->release_ctrl_lines(this->src_id);
this->exception |= EXC_ARB_LOST;
this->int_stat |= INT_EXCEPTION;
}
this->int_stat |= INT_CMD_DONE;
update_irq();
break;
case SeqState::SEL_BEGIN:
this->bus_obj->begin_selection(this->src_id, this->dst_id, this->cur_cmd & 0x20);
this->next_state = SeqState::SEL_END;
this->seq_defer_state(SEL_TIME_OUT);
break;
case SeqState::SEL_END:
if (this->bus_obj->end_selection(this->src_id, this->dst_id)) {
this->bus_obj->release_ctrl_line(this->src_id, SCSI_CTRL_SEL);
LOG_F(9, "MESH: selection completed");
} else { // selection timeout
this->bus_obj->disconnect(this->src_id);
this->cur_state = SeqState::IDLE;
this->exception |= EXC_SEL_TIMEOUT;
this->int_stat |= INT_EXCEPTION;
}
this->int_stat |= INT_CMD_DONE;
update_irq();
break;
default:
ABORT_F("MESH: unimplemented sequencer state %d", this->cur_state);
}
}
void MeshController::update_irq()
{
uint8_t new_irq = !!(this->int_stat & this->int_mask);
if (new_irq != this->irq) {
this->irq = new_irq;
this->int_ctrl->ack_int(this->irq_id, new_irq);
}
}
static const DeviceDescription Mesh_Descriptor = {
MeshController::create, {}, {}
};
REGISTER_DEVICE(Mesh, Mesh_Descriptor);