125 lines
2.6 KiB
C
125 lines
2.6 KiB
C
#include <socks/console.h>
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#include <socks/printk.h>
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#include <socks/panic.h>
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#include <arch/serial.h>
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#include <arch/ports.h>
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#define COM1 0x3F8
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#define COM2 0x2F8
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#define COM3 0x3E8
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#define COM4 0x2E8
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static int transmit_empty(int device)
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{
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return inportb(device + 5) & 0x20;
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}
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static int serial_received(int device)
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{
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return inportb(device + 5) & 0x1;
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}
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void serial_send_byte(int device, char out)
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{
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volatile unsigned int _count = 0;
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while (!transmit_empty(device)) {
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_count++;
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}
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outportb(device, out);
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while (!transmit_empty(device)) {
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_count++;
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}
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}
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void serial_putchar(int port, char ch)
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{
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if (ch == '\n') {
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serial_send_byte(port, '\r');
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}
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serial_send_byte(port, ch);
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}
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void serialcon_write(struct console *con, const char *s, unsigned int len)
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{
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for (unsigned int i = 0; i < len; i++) {
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serial_putchar(COM1, s[i]);
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}
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}
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static int get_baud_divisor(int baud)
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{
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int freq = 115200;
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int best_baud = -1;
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int best_div = -1;
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for (int i = 1; i < 254; i++) {
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int this_baud = freq / i;
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if (this_baud == baud) {
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return i;
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}
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if (best_baud == -1) {
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best_baud = this_baud;
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best_div = i;
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continue;
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}
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if (this_baud < baud && best_baud > baud) {
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/* TODO pick divisor that gives the closest baud rate */
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return best_div;
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}
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best_baud = this_baud;
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best_div = i;
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}
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return best_div;
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}
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static void init_serial_port(int port, int baud)
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{
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int baud_div = get_baud_divisor(baud);
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outportb(port + 1, 0x00); // Disable all interrupts
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outportb(port + 3, 0x80); // Enable DLAB (set baud rate divisor)
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outportb(port + 0, baud_div); // Set divisor
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outportb(port + 1, 0x00);
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outportb(port + 3, 0x03); // 8 bits, no parity, one stop bit
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outportb(port + 2, 0xC7); // Enable FIFO, clear them, with 14-byte threshold
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outportb(port + 4, 0x0B); // IRQs enabled, RTS/DSR set
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outportb(port + 4, 0x1E); // Set in loopback mode, test the serial chip
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outportb(port + 0, 0xAE); // Test serial chip (send byte 0xAE and check if serial returns same byte)
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volatile unsigned int q = 0;
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while (!serial_received(port)) {
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q++;
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}
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// Check if serial is faulty (i.e: not same byte as sent)
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if(inportb(port + 0) != 0xAE) {
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panic("serial: port %x init failed", port);
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return;
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}
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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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outportb(port + 4, 0x0F);
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printk("serial: port %x initialised", port);
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}
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static struct console serialcon = {
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.c_name = "serialcon",
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.c_flags = CON_BOOT,
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.c_write = serialcon_write,
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.c_lock = SPIN_LOCK_INIT,
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};
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void serialcon_init(int baud)
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{
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init_serial_port(COM1, baud);
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console_register(&serialcon);
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}
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