🆕 uart驱动

kernel/driver/uart/uart.c

@@ -0,0 +1,88 @@
+#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 = E_UART_BITS_RATE_ERROR / 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, 0x0B);                  // IRQs enabled, RTS/DSR set
+    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, 0x0F);
+    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);
+}

kernel/driver/uart/uart.h

@@ -0,0 +1,64 @@
+/**
+ * @file uart.h
+ * @author longjin (longjin@RinGoTek.cn)
+ * @brief uart驱动程序 RS-232驱动
+ * @version 0.1
+ * @date 2022-04-15
+ * 
+ * @copyright Copyright (c) 2022
+ * 
+ */
+#pragma once
+
+#include <common/glib.h>
+
+#define UART_SUCCESS 0
+#define E_UART_BITS_RATE_ERROR 1
+#define E_UART_SERIAL_FAULT 2
+enum uart_port_io_addr
+{
+    COM1 = 0x3f8,
+    COM2 = 0x2f8,
+    COM3 = 0x3e8,
+    COM4 = 0x2e8,
+    COM5 = 0x5f8,
+    COM6 = 0x4f8,
+    COM7 = 0x5e8,
+    COM8 = 0x4E8,
+};
+
+enum uart_register_offset
+{
+    REG_DATA = 0,
+    REG_INTERRUPT_ENABLE = 1,
+    REG_II_FIFO = 2,    // 	Interrupt Identification and FIFO control registers
+    REG_LINE_CONTROL = 3,
+    REG_MODEM_CONTROL = 4,
+    REG_LINE_STATUS = 5,
+    REG_MODEM_STATUE = 6,
+    REG_SCRATCH = 7
+};
+
+/**
+ * @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);
+
+/**
+ * @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);
+
+/**
+ * @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);