component serport """Hardware driver for the digital I/O bits of the 8250 and 16550 serial port.

.B loadrt serport io=\\fIaddr[,addr...]\\fR
.PP
The pin numbers refer to the 9-pin serial pinout.  Keep in mind that these ports generally use rs232 voltages, not 0/5V signals.

Specify the I/O address of the serial ports using the module parameter
\\fBio=\\fIaddr[,addr...]\\fR.  These ports must not be in use by the kernel.
To free up the I/O ports after bootup, install setserial and execute a command
like:
.RS 
sudo setserial /dev/ttyS0 uart none
.RE
but it is best to ensure that the serial port is never used or configured by
the Linux kernel by setting a kernel commandline parameter or not loading
the serial kernel module if it is a modularized driver.
""";

pin out bit pin_1_in "Also called DCD (data carrier detect); pin 8 on the 25-pin serial pinout";
pin out bit pin_6_in "Also called DSR (data set ready); pin 6 on the 25-pin serial pinout";
pin out bit pin_8_in "Also called CTS (clear to send); pin 5 on the 25-pin serial pinout";
pin out bit pin_9_in "Also called RI (ring indicator); pin 22 on the 25-pin serial pinout";

pin out bit pin_1_in_not "Inverted version of pin-1-in";
pin out bit pin_6_in_not "Inverted version of pin-6-in";
pin out bit pin_8_in_not "Inverted version of pin-8-in";
pin out bit pin_9_in_not "Inverted version of pin-9-in";

pin in bit pin_3_out  "Also called TX (transmit data); pin 2 on the 25-pin serial pinout";
pin in bit pin_4_out "Also called DTR (data terminal ready); pin 20 on the 25-pin serial pinout";
pin in bit pin_7_out "Also called RTS (request to send); pin 4 on the 25-pin serial pinout";

param rw bit pin_3_out_invert;
param rw bit pin_4_out_invert;
param rw bit pin_7_out_invert;
param r u32 ioaddr;

option count_function;
option extra_setup;
option extra_cleanup;
option constructable no;

function read nofp;
function write nofp;

license "GPL";
;;

#include <asm/io.h>
#include <rtapi_errno.h>

#define MAX 8
int io[MAX] = {0,};
RTAPI_MP_ARRAY_INT(io, MAX, "I/O addresses of serial ports");

int get_count(void) {
    int i = 0;
    for(i=0; i<MAX && io[i]; i++) { /* Nothing */ }
    return i;
}

EXTRA_SETUP() {
    rtapi_print_msg(RTAPI_MSG_INFO, "requesting I/O region 0x%x\n",
			io[extra_arg]);
    if(!rtapi_request_region(io[extra_arg], 7, "serport")) {
	// set this I/O port to 0 so that EXTRA_CLEANUP does not release the IO
	// ports that were never requested.
	rtapi_print_msg(RTAPI_MSG_ERR,
	    "Could not register port at address 0x%x.  See\n"
	    "'man serport' for information on using 'setserial'\n"
	    "to make a port available to hal", io[extra_arg]);
        io[extra_arg] = 0; 
        return -EBUSY;
    }
    ioaddr = io[extra_arg];
    return 0;
}

EXTRA_CLEANUP() {
    int i;
    for(i=0; i < MAX && io[i]; i++) {
        rtapi_print_msg(RTAPI_MSG_INFO, "releasing I/O region 0x%x\n",
			io[i]);
        rtapi_release_region(io[i], 7);
    }
}

#define MSR (ioaddr + 6)
#define CTS (1<<4)
#define DSR (1<<5)
#define RI (1<<6)
#define DCD (1<<7)

#define MCR (ioaddr + 4)
#define DTR (1<<0)
#define RTS (1<<1)

#define LCR (ioaddr + 3)
#define BREAK (1<<6)

FUNCTION(read) { 
    int i = inb(MSR);

    pin_9_in = (i & RI) == 0;
    pin_9_in_not = (i & RI) == RI;

    pin_1_in = (i & DCD) == 0;
    pin_1_in_not = !(i & DCD) == DCD;

    pin_6_in = (i & DSR) == 0;
    pin_6_in_not = (i & DSR) == DSR;

    pin_8_in = (i & CTS) == 0;
    pin_8_in_not = (i & CTS) == CTS;
}

FUNCTION(write) {
    int i = 0, j=0;

    if(!pin_4_out ^ !pin_4_out_invert) i |= DTR;
    if(!pin_7_out ^ !pin_7_out_invert) i |= RTS;
    if(!pin_3_out ^ !pin_3_out_invert) j |= BREAK;

    outb(i, MCR);
    outb(j, LCR);
}