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Atmosphere/libraries/libexosphere/source/uart/uart_api.cpp

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/*
* Copyright (c) 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 <exosphere.hpp>
#include "uart_registers.hpp"
namespace ams::uart {
namespace {
constexpr inline const u16 UartRegisterOffsets[Port_Count] = {
secmon::MemoryRegionPhysicalDeviceUartA.GetAddress() - secmon::MemoryRegionPhysicalDeviceUart.GetAddress(),
secmon::MemoryRegionPhysicalDeviceUartB.GetAddress() - secmon::MemoryRegionPhysicalDeviceUart.GetAddress(),
secmon::MemoryRegionPhysicalDeviceUartC.GetAddress() - secmon::MemoryRegionPhysicalDeviceUart.GetAddress(),
};
constinit uintptr_t g_register_address = secmon::MemoryRegionPhysicalDeviceUart.GetAddress();
volatile UartRegisters *GetRegisters(Port port) {
return reinterpret_cast<volatile UartRegisters *>(g_register_address + UartRegisterOffsets[port]);
}
void WaitSymbols(int baud, u32 num) {
util::WaitMicroSeconds(util::DivideUp(num * 1'000'000, baud));
}
void WaitCycles(int baud, u32 num) {
util::WaitMicroSeconds(util::DivideUp(num * 1'000'000, 16 * baud));
}
ALWAYS_INLINE void WaitFifoNotFull(volatile UartRegisters *uart) {
while ((uart->lsr & UART_LSR_TX_FIFO_FULL) != 0) { /* ... */ }
}
ALWAYS_INLINE void WaitFifoNotEmpty(volatile UartRegisters *uart) {
while ((uart->lsr & UART_LSR_RX_FIFO_EMPTY) != 0) { /* ... */ }
}
void WaitIdle(volatile UartRegisters *uart, u32 vendor_state) {
if (vendor_state & UART_VENDOR_STATE_TX_IDLE) {
while ((uart->lsr & UART_LSR_TMTY) == 0) { /* ... */ }
}
if (vendor_state & UART_VENDOR_STATE_RX_IDLE) {
while ((uart->lsr & UART_LSR_RDR) != 0) { /* ... */ }
}
}
constexpr inline u32 LockBit = (1 << 6);
}
void SetRegisterAddress(uintptr_t address) {
g_register_address = address;
}
void Initialize(Port port, int baud_rate, u32 flags) {
/* Get the registers. */
auto *uart = GetRegisters(port);
/* Parse flags. */
const bool inverted = (flags & Flag_Inverted) != 0;
/* Calculate the baud rate divisor. */
constexpr u32 UartClock = 408000000;
const u32 divisor = (UartClock + (baud_rate * 16) / 2) / (baud_rate * 16);
/* Wait for idle state. */
WaitIdle(uart, UART_VENDOR_STATE_TX_IDLE);
/* Wait 100 us. */
util::WaitMicroSeconds(100);
/* Disable interrupts. */
uart->lcr = uart->lcr & ~UART_LCR_DLAB;
uart->ier = 0;
uart->mcr = 0;
/* Setup the uart in FIFO mode. */
uart->lcr = UART_LCR_DLAB | UART_LCR_WD_LENGTH_8;
uart->dll = static_cast<u8>(divisor);
uart->dlh = static_cast<u8>(divisor >> 8);
uart->lcr = uart->lcr & ~UART_LCR_DLAB;
reg::Read(std::addressof(uart->spr));
/* Wait three symbols. */
WaitSymbols(baud_rate, 3);
/* Enable FIFO with default settings. */
uart->fcr = UART_FCR_FCR_EN_FIFO;
uart->irda_csr = inverted ? UART_IRDA_CSR_INVERT_TXD : 0;
reg::Read(std::addressof(uart->spr));
/* Wait three cycles. */
WaitCycles(baud_rate, 3);
/* Flush the FIFO. */
WaitIdle(uart, UART_VENDOR_STATE_TX_IDLE);
uart->fcr = uart->fcr | UART_FCR_RX_CLR | UART_FCR_TX_CLR;
WaitCycles(baud_rate, 32);
/* Wait for idle state. */
WaitIdle(uart, UART_VENDOR_STATE_TX_IDLE | UART_VENDOR_STATE_RX_IDLE);
/* Wait 100 us. */
util::WaitMicroSeconds(100);
}
void SendText(Port port, const void *data, size_t size) {
/* Get the registers. */
auto *uart = GetRegisters(port);
/* Get pointer to data. */
const u8 *p = static_cast<const u8 *>(data);
/* Send each byte. */
for (size_t i = 0; i < size; ++i) {
WaitFifoNotFull(uart);
if (p[i] == '\n') {
*reinterpret_cast<volatile u8 *>(std::addressof(uart->thr)) = '\r';
WaitFifoNotFull(uart);
}
*reinterpret_cast<volatile u8 *>(std::addressof(uart->thr)) = p[i];
}
}
void WaitFlush(Port port) {
/* Get the registers. */
auto *uart = GetRegisters(port);
/* Wait for idle. */
WaitIdle(uart, UART_VENDOR_STATE_TX_IDLE);
}
}