163 lines
4.1 KiB
C
163 lines
4.1 KiB
C
/*
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Copyright (C) 2016-2019 The University of Notre Dame
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This software is distributed under the GNU General Public License.
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See the file LICENSE for details.
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*/
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// Derived from: https://wiki.osdev.org/Serial_Ports#Example_Code
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// For more info:
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// https://wiki.osdev.org/Serial_Ports
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// http://www.webcitation.org/5ugQv5JOw
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#include "kernel/types.h"
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#include "ioports.h"
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#include "string.h"
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#include "device.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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#define SERIAL_DATA 0 // If DLAB disabled in LCR
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#define SERIAL_IRQ_ENABLE 1 // If DLAB disabled in LCR
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#define SERIAL_IRQ_DATA_AVAILABILE (0x01 << 0)
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#define SERIAL_IRQ_TRASMITTER_EMPTY (0x01 << 1)
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#define SERIAL_IRQ_ERROR (0x01 << 2)
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#define SERIAL_IRQ_STATUS_CHANGE (0x01 << 3)
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#define SERIAL_DIVISOR_LO 0 // If DLAB enabled in LCR
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#define SERIAL_DIVISOR_HI 1 // If DLAB enabled in LCR
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#define SERIAL_FCR 2
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#define SERIAL_FIFO_ENABLE (0x01 << 0)
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#define SERIAL_FIFO_CLEAR_RECIEVER (0x01 << 1)
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#define SERIAL_FIFO_CLEAR_TRANSMITTER (0x01 << 2)
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#define SERIAL_FIFO_DMA_MODE (0x01 << 3)
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#define SERIAL_TRIGGER_LEVEL0 (0x01 << 6)
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#define SERIAL_TRIGGER_LEVEL1 (0x01 << 7)
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#define SERIAL_LCR 3
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#define SERIAL_CHARLEN_START (0x01 << 0)
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#define SERIAL_STOP_BITS (0x01 << 2)
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#define SERIAL_DLAB_ENABLE (0x01 << 3)
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#define SERIAL_MCR 4
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#define SERIAL_DATA_TERMINAL_READY (0x01 << 0)
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#define SERIAL_REQUEST_TO_SEND (0x01 << 1)
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#define SERIAL_AUX_OUT1 (0x01 << 2)
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#define SERIAL_AUX_OUT2 (0x01 << 3)
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#define SERIAL_LSR 5
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#define SERIAL_DATA_AVAILABLE (0x01 << 0)
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#define SERIAL_TRANSMIT_EMPTY (0x01 << 5)
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#define SERIAL_MSR 6
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#define SERIAL_SCRATCH 7
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static const int serial_ports[4] = { COM1, COM2, COM3, COM4 };
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static void serial_init_port(int port)
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{
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//Disable iterrupts
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outb(0x00, port + SERIAL_IRQ_ENABLE);
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//Enable DLAB(set baud rate divisor)
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outb(SERIAL_DLAB_ENABLE, port + SERIAL_LCR);
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//Set divisor to 3(lo byte) 38400 baud
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outb(0x03, port + SERIAL_DIVISOR_LO);
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//(hi byte)
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outb(0x00, port + SERIAL_DIVISOR_HI);
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//8 bits, no parity, one stop bit
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outb(SERIAL_CHARLEN_START * 3, port + SERIAL_LCR);
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//Enable FIFO, clear them, with 14 - byte threshold
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outb(SERIAL_FIFO_ENABLE | SERIAL_FIFO_CLEAR_RECIEVER | SERIAL_FIFO_CLEAR_TRANSMITTER | SERIAL_TRIGGER_LEVEL0 | SERIAL_TRIGGER_LEVEL1, port + SERIAL_FCR);
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//IRQs enabled, RTS / DSR set
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outb(SERIAL_DATA_TERMINAL_READY | SERIAL_REQUEST_TO_SEND | SERIAL_AUX_OUT2, port + SERIAL_MCR);
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}
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static int serial_received(int port)
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{
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return inb(port + SERIAL_LSR) & SERIAL_DATA_AVAILABLE;
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}
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static int is_transmit_empty(int port)
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{
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return inb(port + SERIAL_LSR) & SERIAL_TRANSMIT_EMPTY;
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}
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static int is_valid_port(uint8_t port_no)
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{
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return port_no < sizeof(serial_ports) / sizeof(int);
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}
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char serial_read(uint8_t port_no)
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{
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if(!is_valid_port(port_no))
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return -1;
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while(serial_received(serial_ports[port_no]) == 0);
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return inb(serial_ports[port_no]);
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}
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int serial_write(uint8_t port_no, char a)
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{
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if(!is_valid_port(port_no))
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return -1;
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while(is_transmit_empty(serial_ports[port_no]) == 0);
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outb(a, serial_ports[port_no]);
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return 0;
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}
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int serial_device_probe( int unit, int *blocksize, int *nblocks, char *info )
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{
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if(unit<0 || unit>3) return 0;
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serial_init_port(serial_ports[unit]);
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*blocksize = 1;
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*nblocks = 0;
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strcpy(info,"serial");
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return 1;
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}
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int serial_device_read( int unit, void *data, int length, int offset )
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{
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int i;
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char *cdata = data;
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for(i=0;i<length;i++) {
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cdata[i] = serial_read(unit);
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}
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return length;
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}
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int serial_device_write( int unit, const void *data, int length, int offset )
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{
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int i;
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const char *cdata = data;
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for(i=0;i<length;i++) {
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serial_write(unit,cdata[i]);
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}
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return length;
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}
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static struct device_driver serial_driver = {
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.name = "serial",
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.probe = serial_device_probe,
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.read = serial_device_read,
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.read_nonblock = serial_device_read,
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.write = serial_device_write
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};
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void serial_init()
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{
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int i;
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for(i = 0; i < sizeof(serial_ports) / sizeof(int); i++) {
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serial_init_port(serial_ports[i]);
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}
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device_driver_register(&serial_driver);
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}
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