// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * (c) 1997-1998  Grant R. Guenther <grant@torque.net>
 *
 * comm.c is a low-level protocol driver for some older models of the DataStor
 * "Commuter" parallel to IDE adapter. Some of the parallel port devices
 * marketed by Arista currently use this adapter.
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/wait.h>
#include <asm/io.h>
#include "pata_parport.h"

/*
 * mode codes:  0  nybble reads, 8-bit writes
 *              1  8-bit reads and writes
 *              2  8-bit EPP mode
 */

#define j44(a, b)       (((a >> 3) & 0x0f) | ((b << 1) & 0xf0))

#define P1      w2(5);w2(0xd);w2(0xd);w2(5);w2(4);
#define P2      w2(5);w2(7);w2(7);w2(5);w2(4);

/*
 * cont = 0 - access the IDE register file
 * cont = 1 - access the IDE command set
 */
static int  cont_map[2] = { 0x08, 0x10 };

static int comm_read_regr(struct pi_adapter *pi, int cont, int regr)
{
        int l, h, r;

        r = regr + cont_map[cont];

        switch (pi->mode) {
        case 0:
                w0(r); P1; w0(0);
                w2(6); l = r1(); w0(0x80); h = r1(); w2(4);
                return j44(l, h);

        case 1:
                w0(r+0x20); P1;
                w0(0); w2(0x26); h = r0(); w2(4);
                return h;

        case 2:
        case 3:
        case 4:
                w3(r+0x20); (void)r1();
                w2(0x24); h = r4(); w2(4);
                return h;
        }

        return -1;
}

static void comm_write_regr(struct pi_adapter *pi, int cont, int regr, int val)
{
        int r = regr + cont_map[cont];

        switch (pi->mode) {
        case 0:
        case 1:
                w0(r); P1; w0(val); P2;
                break;
        case 2:
        case 3:
        case 4:
                w3(r); (void)r1(); w4(val);
                break;
        }
}

static void comm_connect(struct pi_adapter *pi)
{
        pi->saved_r0 = r0();
        pi->saved_r2 = r2();
        w2(4); w0(0xff); w2(6);
        w2(4); w0(0xaa); w2(6);
        w2(4); w0(0x00); w2(6);
        w2(4); w0(0x87); w2(6);
        w2(4); w0(0xe0); w2(0xc); w2(0xc); w2(4);
}

static void comm_disconnect(struct pi_adapter *pi)
{
        w2(0); w2(0); w2(0); w2(4);
        w0(pi->saved_r0);
        w2(pi->saved_r2);
}

static void comm_read_block(struct pi_adapter *pi, char *buf, int count)
{
        int i, l, h;

        switch (pi->mode) {
        case 0:
                w0(0x48); P1;
                for (i = 0; i < count; i++) {
                        w0(0); w2(6); l = r1();
                        w0(0x80); h = r1(); w2(4);
                        buf[i] = j44(l, h);
                }
                break;
        case 1:
                w0(0x68); P1; w0(0);
                for (i = 0; i < count; i++) {
                        w2(0x26);
                        buf[i] = r0();
                        w2(0x24);
                }
                w2(4);
                break;
        case 2:
                w3(0x68); (void)r1(); w2(0x24);
                for (i = 0; i < count; i++)
                        buf[i] = r4();
                w2(4);
                break;
        case 3:
                w3(0x68); (void)r1(); w2(0x24);
                for (i = 0; i < count / 2; i++)
                        ((u16 *)buf)[i] = r4w();
                w2(4);
                break;
        case 4:
                w3(0x68); (void)r1(); w2(0x24);
                for (i = 0; i < count / 4; i++)
                        ((u32 *)buf)[i] = r4l();
                w2(4);
                break;
        }
}

/* NB: Watch out for the byte swapped writes ! */
static void comm_write_block(struct pi_adapter *pi, char *buf, int count)
{
        int k;

        switch (pi->mode) {
        case 0:
        case 1:
                w0(0x68); P1;
                for (k = 0; k < count; k++) {
                        w2(5);
                        w0(buf[k ^ 1]);
                        w2(7);
                }
                w2(5); w2(4);
                break;
        case 2:
                w3(0x48); (void)r1();
                for (k = 0; k < count; k++)
                        w4(buf[k ^ 1]);
                break;
        case 3:
                w3(0x48); (void)r1();
                for (k = 0; k < count / 2; k++)
                        w4w(swab16(((u16 *)buf)[k]));
                break;
        case 4:
                w3(0x48); (void)r1();
                for (k = 0; k < count / 4; k++)
                        w4l(swab16(((u16 *)buf)[2 * k]) |
                            swab16(((u16 *)buf)[2 * k + 1]) << 16);
                break;
        }
}

static void comm_log_adapter(struct pi_adapter *pi)
{
        char *mode_string[5] = { "4-bit", "8-bit", "EPP-8", "EPP-16", "EPP-32" };

        dev_info(&pi->dev,
                 "DataStor Commuter at 0x%x, mode %d (%s), delay %d\n",
                 pi->port, pi->mode, mode_string[pi->mode], pi->delay);
}

static struct pi_protocol comm = {
        .owner          = THIS_MODULE,
        .name           = "comm",
        .max_mode       = 5,
        .epp_first      = 2,
        .default_delay  = 1,
        .max_units      = 1,
        .write_regr     = comm_write_regr,
        .read_regr      = comm_read_regr,
        .write_block    = comm_write_block,
        .read_block     = comm_read_block,
        .connect        = comm_connect,
        .disconnect     = comm_disconnect,
        .log_adapter    = comm_log_adapter,
};

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Grant R. Guenther <grant@torque.net>");
MODULE_DESCRIPTION("DataStor Commuter parallel port IDE adapter protocol driver");
module_pata_parport_driver(comm);