dingusppc/devices/common/scsi/scsi_bus.cpp

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/*
DingusPPC - The Experimental PowerPC Macintosh emulator
Copyright (C) 2018-22 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 <https://www.gnu.org/licenses/>.
*/
/** @file SCSI bus emulation. */
#include <devices/common/hwcomponent.h>
#include <devices/common/scsi/scsi.h>
#include <loguru.hpp>
#include <cinttypes>
ScsiBus::ScsiBus()
{
supports_types(HWCompType::SCSI_BUS);
for(int i = 0; i < SCSI_MAX_DEVS; i++) {
this->devices[i] = nullptr;
this->dev_ctrl_lines[i] = 0;
}
this->ctrl_lines = 0; // all control lines released
this->data_lines = 0; // data lines released
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this->arb_winner_id = -1;
this->initiator_id = -1;
this->target_id = -1;
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}
void ScsiBus::register_device(int id, ScsiDevice* dev_obj)
{
if (this->devices[id] != nullptr) {
ABORT_F("ScsiBus: device with ID %d already registered", id);
}
this->devices[id] = dev_obj;
}
void ScsiBus::change_bus_phase(int initiator_id)
{
for (int i = 0; i < SCSI_MAX_DEVS; i++) {
if (i == initiator_id)
continue; // don't notify the initiator
if (this->devices[i] != nullptr) {
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this->devices[i]->notify(this, ScsiMsg::BUS_PHASE_CHANGE, this->cur_phase);
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}
}
}
void ScsiBus::assert_ctrl_line(int initiator_id, uint16_t mask)
{
uint16_t new_state = 0xFFFFU & mask;
this->dev_ctrl_lines[initiator_id] = new_state;
if (new_state == this->ctrl_lines) {
return;
}
this->ctrl_lines = new_state;
if (new_state & SCSI_CTRL_RST) {
this->cur_phase = ScsiPhase::RESET;
change_bus_phase(initiator_id);
}
}
void ScsiBus::release_ctrl_line(int id, uint16_t mask)
{
uint16_t new_state = 0;
this->dev_ctrl_lines[id] &= ~mask;
// OR control lines of all devices together
for (int i = 0; i < SCSI_MAX_DEVS; i++) {
new_state |= this->dev_ctrl_lines[i];
}
if (this->ctrl_lines & SCSI_CTRL_RST) {
if (!(new_state & SCSI_CTRL_RST)) {
this->ctrl_lines = new_state;
this->cur_phase = ScsiPhase::BUS_FREE;
change_bus_phase(id);
}
} else {
this->ctrl_lines = new_state;
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}
}
void ScsiBus::release_ctrl_lines(int id)
{
this->release_ctrl_line(id, 0xFFFFUL);
}
uint16_t ScsiBus::test_ctrl_lines(uint16_t mask)
{
uint16_t new_state = 0;
// OR control lines of all devices together
for (int i = 0; i < SCSI_MAX_DEVS; i++) {
new_state |= this->dev_ctrl_lines[i];
}
return new_state & mask;
}
int ScsiBus::switch_phase(int id, int new_phase)
{
int old_phase = this->cur_phase;
// leave the current phase (low-level)
switch (old_phase) {
case ScsiPhase::COMMAND:
this->release_ctrl_line(id, SCSI_CTRL_CD);
break;
case ScsiPhase::DATA_IN:
this->release_ctrl_line(id, SCSI_CTRL_IO);
break;
}
// enter new phase (low-level)
switch (new_phase) {
case ScsiPhase::COMMAND:
this->assert_ctrl_line(id, SCSI_CTRL_CD);
break;
case ScsiPhase::DATA_IN:
this->assert_ctrl_line(id, SCSI_CTRL_IO);
break;
}
// switch the bus to the new phase (high-level)
this->cur_phase = new_phase;
change_bus_phase(id);
return old_phase;
}
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bool ScsiBus::begin_arbitration(int initiator_id)
{
if (this->cur_phase == ScsiPhase::BUS_FREE) {
this->data_lines |= 1 << initiator_id;
this->cur_phase = ScsiPhase::ARBITRATION;
change_bus_phase(initiator_id);
return true;
} else {
return false;
}
}
bool ScsiBus::end_arbitration(int initiator_id)
{
int highest_id = -1;
// find the highest ID bit on the data lines
for (int id = 7; id >= 0; id--) {
if (this->data_lines & (1 << id)) {
highest_id = id;
break;
}
}
if (highest_id >= 0) {
this->arb_winner_id = highest_id;
}
return highest_id == initiator_id;
}
bool ScsiBus::begin_selection(int initiator_id, int target_id, bool atn)
{
// perform bus integrity checks
if (this->cur_phase != ScsiPhase::ARBITRATION || this->arb_winner_id != initiator_id)
return false;
this->assert_ctrl_line(initiator_id, SCSI_CTRL_SEL);
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this->data_lines |= (1 << initiator_id) | (1 << target_id);
if (atn) {
assert_ctrl_line(initiator_id, SCSI_CTRL_ATN);
}
this->initiator_id = initiator_id;
this->cur_phase = ScsiPhase::SELECTION;
change_bus_phase(initiator_id);
return true;
}
void ScsiBus::confirm_selection(int target_id)
{
this->target_id = target_id;
// notify initiator about selection confirmation from target
if (this->initiator_id >= 0) {
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this->devices[this->initiator_id]->notify(this, ScsiMsg::CONFIRM_SEL, target_id);
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}
}
bool ScsiBus::end_selection(int initiator_id, int target_id)
{
// check for selection confirmation from target
return this->target_id == target_id;
}
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bool ScsiBus::transfer_command(uint8_t* dst_ptr)
{
static uint8_t cmd_to_cdb_length[8] = {6, 10, 10, 6, 6, 12, 6, 6};
this->switch_phase(target_id, ScsiPhase::COMMAND);
this->devices[this->initiator_id]->notify(this, ScsiMsg::SEND_CMD_BEGIN, 0);
// attempt to transfer the shortest Command Description Block (CDB)
if (!this->devices[this->initiator_id]->send_bytes(dst_ptr, 6)) {
LOG_F(ERROR, "ScsiBus: error while transferring CDB!");
return false;
}
// transfer the remaining CDB bytes if any
int cdb_length = cmd_to_cdb_length[dst_ptr[0] >> 5];
if (cdb_length > 6) {
if (!this->devices[this->initiator_id]->send_bytes(dst_ptr + 6, cdb_length - 6)) {
LOG_F(ERROR, "ScsiBus: error while transferring CDB!");
return false;
}
}
this->devices[this->initiator_id]->notify(this, ScsiMsg::SEND_CMD_END, 0);
return true;
}
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void ScsiBus::disconnect(int dev_id)
{
this->release_ctrl_lines(dev_id);
if (!(this->ctrl_lines & SCSI_CTRL_BSY) && !(this->ctrl_lines & SCSI_CTRL_SEL)) {
this->cur_phase = ScsiPhase::BUS_FREE;
change_bus_phase(dev_id);
}
}