45 lines
1.5 KiB
C
45 lines
1.5 KiB
C
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#include <kernel/serial.h>
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#include <kernel/io.h>
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#include <kernel/kernel.h>
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uint8_t serial_port_init(int port) {
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// Test port by seeing if scratch register can store a value
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uint8_t old_scratch = inb(port + 7);
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outb(port + 7, old_scratch + 1);
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if (inb(port + 7) != old_scratch + 1)
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return 0;
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outb(port + 7, old_scratch);
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outb(port + 1, 0x00); // Disable all interrupts
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outb(port + 3, 0x80); // Enable DLAB (set baud rate divisor)
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outb(port + 0, 0x03); // Set divisor to 3 (lo byte) 38400 baud
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outb(port + 1, 0x00); // (hi byte)
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outb(port + 3, 0x03); // 8 bits, no parity, one stop bit
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outb(port + 2, 0xC7); // Enable FIFO, clear them, with 14-byte threshold
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outb(port + 4, 0x0B); // IRQs enabled, RTS/DSR set
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outb(port + 4, 0x1E); // Set in loopback mode, test the serial chip
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outb(port + 0, 0xAE); // Test serial chip (send byte 0xAE and check if serial returns same byte)
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// Check if serial is faulty (i.e: not same byte as sent)
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if(inb(port + 0) != 0xAE)
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return 0;
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// If serial is not faulty set it in normal operation mode
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// (not-loopback with IRQs enabled and OUT#1 and OUT#2 bits enabled)
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outb(port + 4, 0x0F);
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return 1;
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}
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void serial_putc(int port, const char c) {
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// Poll until transmit is empty
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while(!IS_TRANSMIT_EMPTY(port)) cpu_relax;
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outb(port, c);
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}
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void serial_puts(int port, const char *str) {
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while (*str) {
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serial_putc(port, str[0]);
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str++;
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}
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}
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