mirror of
https://github.com/DragonOS-Community/DragonOS.git
synced 2025-06-09 23:46:48 +00:00
112 lines
3.0 KiB
C
112 lines
3.0 KiB
C
#include "uart.h"
|
||
#include <common/kprint.h>
|
||
|
||
#define UART_MAX_BITS_RATE 115200
|
||
|
||
/**
|
||
* @brief 当前是否有数据到达
|
||
*
|
||
*/
|
||
#define serial_received(p) ((io_in8(p + 5) & 1))
|
||
|
||
/**
|
||
* @brief 当前是否有数据正等待发送
|
||
*
|
||
*/
|
||
#define is_transmit_empty(p) ((io_in8(p + 5) & 0x20))
|
||
|
||
/**
|
||
* @brief 初始化com口
|
||
*
|
||
* @param port com口的端口号
|
||
* @param bits_rate 通信的比特率
|
||
*/
|
||
int uart_init(uint32_t port, uint32_t bits_rate)
|
||
{
|
||
// 错误的比特率
|
||
if (bits_rate > UART_MAX_BITS_RATE || UART_MAX_BITS_RATE % bits_rate != 0)
|
||
return E_UART_BITS_RATE_ERROR;
|
||
|
||
io_out8(port + 1, 0x00); // Disable all interrupts
|
||
io_out8(port + 3, 0x80); // Enable DLAB (set baud rate divisor)
|
||
|
||
uint16_t divisor = UART_MAX_BITS_RATE / bits_rate;
|
||
|
||
io_out8(port + 0, divisor & 0xff); // Set divisor (lo byte)
|
||
io_out8(port + 1, (divisor >> 8) & 0xff); // (hi byte)
|
||
io_out8(port + 3, 0x03); // 8 bits, no parity, one stop bit
|
||
io_out8(port + 2, 0xC7); // Enable FIFO, clear them, with 14-byte threshold
|
||
io_out8(port + 4, 0x08); // IRQs enabled, RTS/DSR clear (现代计算机上一般都不需要hardware flow control,因此不需要置位RTS/DSR)
|
||
io_out8(port + 4, 0x1E); // Set in loopback mode, test the serial chip
|
||
io_out8(port + 0, 0xAE); // Test serial chip (send byte 0xAE and check if serial returns same byte)
|
||
|
||
// Check if serial is faulty (i.e: not same byte as sent)
|
||
if (io_in8(port + 0) != 0xAE)
|
||
{
|
||
return E_UART_SERIAL_FAULT;
|
||
}
|
||
|
||
// If serial is not faulty set it in normal operation mode
|
||
// (not-loopback with IRQs enabled and OUT#1 and OUT#2 bits enabled)
|
||
io_out8(port + 4, 0x08);
|
||
|
||
char init_text2[] = "uart initialized.\n";
|
||
for (int i = 0; i < sizeof(init_text2) - 1; ++i)
|
||
uart_send(COM1, init_text2[i]);
|
||
return UART_SUCCESS;
|
||
|
||
/*
|
||
Notice that the initialization code above writes to [PORT + 1]
|
||
twice with different values. This is once to write to the Divisor
|
||
register along with [PORT + 0] and once to write to the Interrupt
|
||
register as detailed in the previous section.
|
||
The second write to the Line Control register [PORT + 3]
|
||
clears the DLAB again as well as setting various other bits.
|
||
*/
|
||
}
|
||
|
||
/**
|
||
* @brief 发送数据
|
||
*
|
||
* @param port 端口号
|
||
* @param c 要发送的数据
|
||
*/
|
||
void uart_send(uint32_t port, char c)
|
||
{
|
||
while (is_transmit_empty(port) == 0)
|
||
pause();
|
||
io_out8(port, c);
|
||
}
|
||
|
||
/**
|
||
* @brief 从uart接收数据
|
||
*
|
||
* @param port 端口号
|
||
* @return uchar 接收到的数据
|
||
*/
|
||
uchar uart_read(uint32_t port)
|
||
{
|
||
while (serial_received(port) == 0)
|
||
pause();
|
||
|
||
return io_in8(port);
|
||
}
|
||
|
||
/**
|
||
* @brief 通过串口发送整个字符串
|
||
*
|
||
* @param port 串口端口
|
||
* @param str 字符串
|
||
*/
|
||
void uart_send_str(uint32_t port, const char *str)
|
||
{
|
||
if ((unlikely(str == NULL)))
|
||
return;
|
||
while (1)
|
||
{
|
||
if (unlikely(*str == '\0'))
|
||
return;
|
||
uart_send(port, *str);
|
||
++str;
|
||
}
|
||
} |