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Initial emulation of the Athens clock ASIC.

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Maxim Poliakovski 2022-08-06 19:37:10 +02:00
parent 9a6336adb9
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136
devices/common/i2c/athens.cpp Normal file
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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 Athens clock generator emulation. */
/**
Athens (Apple part# 343S1191) is a programmable clock generator ASIC
used in the PCI Power Macintosh computers.
It has two outputs: system clock and video aka dot clock. Both can be
programmed using HW jumpers or I2C interface.
This high-level emulator focuses on the Athen's I2C interface providing
methods for querying the resulting virtual frequences.
This is helpful especially for calculating video parameters.
*/
#include <devices/common/i2c/athens.h>
#include <loguru.hpp>
#include <cinttypes>
#include <vector>
AthensClocks::AthensClocks(uint8_t dev_addr)
{
supports_types(HWCompType::I2C_DEV);
this->my_addr = dev_addr;
// set up power on values
this->regs[AthensRegs::P2_MUX2] = 0x62;
}
void AthensClocks::start_transaction()
{
this->pos = 0; // reset read/write position
}
bool AthensClocks::send_subaddress(uint8_t sub_addr)
{
LOG_F(INFO, "Athens: subaddress set to 0x%X", sub_addr);
return true;
}
bool AthensClocks::send_byte(uint8_t data)
{
switch (this->pos) {
case 0:
this->reg_num = data;
this->pos++;
break;
case 1:
if (this->reg_num >= ATHENS_NUM_REGS) {
LOG_F(WARNING, "Athens: invalid register number %d", this->reg_num);
return false; // return NACK
}
this->regs[this->reg_num] = data;
if (reg_num == 3) {
LOG_F(INFO, "Athens: dot clock frequency set to %d Hz", get_dot_freq());
}
break;
default:
LOG_F(WARNING, "Athens: too much data received!");
return false; // return NACK
}
return true;
}
bool AthensClocks::receive_byte(uint8_t* p_data)
{
LOG_F(INFO, "Athens: receive_byte called");
return false; // return NACK for now
}
int AthensClocks::get_sys_freq()
{
return 0;
}
int AthensClocks::get_dot_freq()
{
static std::vector<int> D2_commons = {7, 11, 13, 14, 15, 17, 23, 31};
static std::vector<int> N2_commons = {
22, 27, 28, 31, 35, 37, 38, 42, 49, 55, 56, 78, 125
};
float out_freq = 0.0f;
int d2 = this->regs[AthensRegs::D2];
int n2 = this->regs[AthensRegs::N2];
int post_div = 1 << (3 - (this->regs[AthensRegs::P2_MUX2] & 3));
if (std::find(D2_commons.begin(), D2_commons.end(), d2) == D2_commons.end()) {
LOG_F(WARNING, "Athens: untested D2 value %d", d2);
}
if (std::find(N2_commons.begin(), N2_commons.end(), n2) == N2_commons.end()) {
LOG_F(WARNING, "Athens: untested N2 value %d", d2);
}
int mux = (this->regs[AthensRegs::P2_MUX2] >> 4) & 3;
switch (mux) {
case 0: // clock source -> dot cock VCO
out_freq = ATHENS_XTAL * ((float)n2 / (float)(d2 * post_div));
break;
case 1: // clock source -> system clock VCO
LOG_F(WARNING, "Athens: system clock VCO not supported yet!");
break;
case 2: // clock source -> crystal frequency
out_freq = ATHENS_XTAL / post_div;
break;
case 3:
LOG_F(WARNING, "Athens: attempt to use reserved Mux value!");
break;
}
return static_cast<int>(out_freq + 0.5f);
}

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devices/common/i2c/athens.h Normal file
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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 Athens clock generator definitions. */
#ifndef ATHENS_H
#define ATHENS_H
#include <devices/common/hwcomponent.h>
#include <devices/common/i2c/i2c.h>
#include <cinttypes>
#define ATHENS_NUM_REGS 8
constexpr auto ATHENS_XTAL = 31334400.0f; // external crystal oscillator frequency
namespace AthensRegs {
enum AthensRegs: uint8_t {
ID = 0,
D2 = 1,
N2 = 2,
P2_MUX2 = 3,
VN_CTRL = 4, // vendor specific control bits
BD1 = 5,
BN1 = 6,
P1 = 7
};
}; // namespace AthensRegs
class AthensClocks : public I2CDevice, public HWComponent
{
public:
AthensClocks(uint8_t dev_addr);
~AthensClocks() = default;
// I2CDevice methods
void start_transaction();
bool send_subaddress(uint8_t sub_addr);
bool send_byte(uint8_t data);
bool receive_byte(uint8_t* p_data);
// methods for querying virtual frequences
int get_sys_freq();
int get_dot_freq();
private:
uint8_t my_addr = 0;
uint8_t reg_num = 0;
int pos = 0;
uint8_t regs[ATHENS_NUM_REGS];
};
#endif // ATHENS_H