RASCSI/cpp/hal/systimer_raspberry.cpp

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//---------------------------------------------------------------------------
//
// SCSI Target Emulator PiSCSI
// for Raspberry Pi
//
// Powered by XM6 TypeG Technology.
// Copyright (C) 2016-2020 GIMONS
// Copyright (C) 2022 akuker
//
// [ High resolution timer ]
//
//---------------------------------------------------------------------------
#include "hal/systimer_raspberry.h"
#include <spdlog/spdlog.h>
#include <memory>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include "hal/gpiobus.h"
#include "hal/sbc_version.h"
// System timer address
volatile uint32_t *SysTimer_Raspberry::systaddr = nullptr;
// ARM timer address
volatile uint32_t *SysTimer_Raspberry::armtaddr = nullptr;
volatile uint32_t SysTimer_Raspberry::corefreq = 0;
using namespace std;
//---------------------------------------------------------------------------
//
// Initialize the system timer
//
//---------------------------------------------------------------------------
void SysTimer_Raspberry::Init()
{
// Get the base address
const auto baseaddr = SBC_Version::GetPeripheralAddress();
// Open /dev/mem
int mem_fd = open("/dev/mem", O_RDWR | O_SYNC);
if (mem_fd == -1) {
spdlog::error("Error: Unable to open /dev/mem. Are you running as root?");
return;
}
// Map peripheral region memory
void *map = mmap(nullptr, 0x1000100, PROT_READ | PROT_WRITE, MAP_SHARED, mem_fd, baseaddr);
if (map == MAP_FAILED) {
spdlog::error("Error: Unable to map memory");
close(mem_fd);
return;
}
close(mem_fd);
// RPI Mailbox property interface
// Get max clock rate
// Tag: 0x00030004
//
// Request: Length: 4
// Value: u32: clock id
// Response: Length: 8
// Value: u32: clock id, u32: rate (in Hz)
//
// Clock id
// 0x000000004: CORE
const array<uint32_t, 32> maxclock = {32, 0, 0x00030004, 8, 0, 4, 0, 0};
// Save the base address
systaddr = (uint32_t *)map + SYST_OFFSET / sizeof(uint32_t);
armtaddr = (uint32_t *)map + ARMT_OFFSET / sizeof(uint32_t);
// Change the ARM timer to free run mode
armtaddr[ARMT_CTRL] = 0x00000282;
// Get the core frequency
if (int vcio_fd = open("/dev/vcio", O_RDONLY); vcio_fd >= 0) {
ioctl(vcio_fd, _IOWR(100, 0, char *), maxclock.data());
corefreq = maxclock[6] / 1000000;
close(vcio_fd);
}
}
//---------------------------------------------------------------------------
//
// Get system timer low byte
//
//---------------------------------------------------------------------------
uint32_t SysTimer_Raspberry::GetTimerLow()
{
return systaddr[SYST_CLO];
}
//---------------------------------------------------------------------------
//
// Get system timer high byte
//
//---------------------------------------------------------------------------
uint32_t SysTimer_Raspberry::GetTimerHigh()
{
return systaddr[SYST_CHI];
}
//---------------------------------------------------------------------------
//
// Sleep in nanoseconds
//
//---------------------------------------------------------------------------
void SysTimer_Raspberry::SleepNsec(uint32_t nsec)
{
// If time is 0, don't do anything
if (nsec == 0) {
return;
}
// Calculate the timer difference
const uint32_t diff = corefreq * nsec / 1000;
// Return if the difference in time is too small
if (diff == 0) {
return;
}
// Start
const uint32_t start = armtaddr[ARMT_FREERUN];
// Loop until timer has elapsed
while ((armtaddr[ARMT_FREERUN] - start) < diff)
;
}
//---------------------------------------------------------------------------
//
// Sleep in microseconds
//
//---------------------------------------------------------------------------
void SysTimer_Raspberry::SleepUsec(uint32_t usec)
{
// If time is 0, don't do anything
if (usec == 0) {
return;
}
const uint32_t now = GetTimerLow();
while ((GetTimerLow() - now) < usec)
;
}