Atmosphere/libraries/libmesosphere/source/kern_debug_log_impl.board.nintendo_nx.cpp

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/*
* Copyright (c) 2018-2020 Atmosphère-NX
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope 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 <http://www.gnu.org/licenses/>.
*/
#include <mesosphere.hpp>
#include "kern_debug_log_impl.hpp"
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namespace ams::kern {
namespace {
enum UartRegister {
UartRegister_THR = 0,
UartRegister_IER = 1,
UartRegister_FCR = 2,
UartRegister_LCR = 3,
UartRegister_LSR = 5,
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UartRegister_IRDA_CSR = 8,
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UartRegister_DLL = 0,
UartRegister_DLH = 1,
};
KVirtualAddress g_uart_address = 0;
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constinit u32 g_saved_registers[5];
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NOINLINE u32 ReadUartRegister(UartRegister which) {
return GetPointer<volatile u32>(g_uart_address)[which];
}
NOINLINE void WriteUartRegister(UartRegister which, u32 value) {
GetPointer<volatile u32>(g_uart_address)[which] = value;
}
}
bool KDebugLogImpl::Initialize() {
/* Set the uart register base address. */
g_uart_address = KMemoryLayout::GetDeviceVirtualAddress(KMemoryRegionType_Uart);
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/* Parameters for uart. */
constexpr u32 BaudRate = 115200;
constexpr u32 Pllp = 408000000;
constexpr u32 Rate = 16 * BaudRate;
constexpr u32 Divisor = (Pllp + Rate / 2) / Rate;
/* Initialize the UART registers. */
/* Set Divisor Latch Access bit, to allow access to DLL/DLH */
WriteUartRegister(UartRegister_LCR, 0x80);
ReadUartRegister(UartRegister_LCR);
/* Program the divisor into DLL/DLH. */
WriteUartRegister(UartRegister_DLL, Divisor & 0xFF);
WriteUartRegister(UartRegister_DLH, (Divisor >> 8) & 0xFF);
ReadUartRegister(UartRegister_DLH);
/* Set word length to 3, clear Divisor Latch Access. */
WriteUartRegister(UartRegister_LCR, 0x03);
ReadUartRegister(UartRegister_LCR);
/* Disable UART interrupts. */
WriteUartRegister(UartRegister_IER, 0x00);
/* Configure the FIFO to be enabled and clear receive. */
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WriteUartRegister(UartRegister_FCR, 0x03);
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WriteUartRegister(UartRegister_IRDA_CSR, 0x02);
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ReadUartRegister(UartRegister_FCR);
return true;
}
void KDebugLogImpl::PutChar(char c) {
while (ReadUartRegister(UartRegister_LSR) & 0x100) {
/* While the FIFO is full, yield. */
cpu::Yield();
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}
WriteUartRegister(UartRegister_THR, c);
cpu::DataSynchronizationBarrier();
}
void KDebugLogImpl::Flush() {
while ((ReadUartRegister(UartRegister_LSR) & 0x40) == 0) {
/* Wait for the TMTY bit to be one (transmit empty). */
}
}
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void KDebugLogImpl::Save() {
/* Save LCR, IER, FCR. */
g_saved_registers[0] = ReadUartRegister(UartRegister_LCR);
g_saved_registers[1] = ReadUartRegister(UartRegister_IER);
g_saved_registers[2] = ReadUartRegister(UartRegister_FCR);
/* Set Divisor Latch Access bit, to allow access to DLL/DLH */
WriteUartRegister(UartRegister_LCR, 0x80);
ReadUartRegister(UartRegister_LCR);
/* Save DLL/DLH. */
g_saved_registers[3] = ReadUartRegister(UartRegister_DLL);
g_saved_registers[4] = ReadUartRegister(UartRegister_DLH);
/* Restore Divisor Latch Access bit. */
WriteUartRegister(UartRegister_LCR, g_saved_registers[0]);
ReadUartRegister(UartRegister_LCR);
}
void KDebugLogImpl::Restore() {
/* Set Divisor Latch Access bit, to allow access to DLL/DLH */
WriteUartRegister(UartRegister_LCR, 0x80);
ReadUartRegister(UartRegister_LCR);
/* Restore DLL/DLH. */
WriteUartRegister(UartRegister_DLL, g_saved_registers[3]);
WriteUartRegister(UartRegister_DLH, g_saved_registers[4]);
ReadUartRegister(UartRegister_DLH);
/* Restore Divisor Latch Access bit. */
WriteUartRegister(UartRegister_LCR, g_saved_registers[0]);
ReadUartRegister(UartRegister_LCR);
/* Restore IER and FCR. */
WriteUartRegister(UartRegister_IER, g_saved_registers[1]);
WriteUartRegister(UartRegister_FCR, g_saved_registers[2] | 2);
WriteUartRegister(UartRegister_IRDA_CSR, 0x02);
ReadUartRegister(UartRegister_FCR);
}
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}