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bugfix: uart在真机上无法初始化的问题

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This commit is contained in:
fslongjin 2022-09-02 12:21:52 +08:00
parent 7d983bd5cb
commit 071392923d
1 changed files with 7 additions and 8 deletions
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15
kernel/driver/uart/uart.c
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@ -13,9 +13,7 @@
* @brief 当前是否有数据正等待发送
*
*/
// todo: 这里有bug，在真机上，一直认为端口是忙的
#define is_transmit_empty(p) ((io_in8(p + 5) & 0x20))
// #define is_transmit_empty(p) (1)
/**
* @brief 初始化com口
@ -32,14 +30,15 @@ int uart_init(uint32_t port, uint32_t bits_rate)
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;
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, 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)
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)
@ -49,9 +48,9 @@ int uart_init(uint32_t port, uint32_t bits_rate)
// 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);
io_out8(port + 4, 0x08);
char init_text2[] = "uart initialized.";
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;