// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * (c) 1997-1998  Grant R. Guenther <grant@torque.net>
 *
 * This is the low level protocol driver for the EPAT parallel
 * to IDE adapter from Shuttle Technologies.  This adapter is
 * used in many popular parallel port disk products such as the
 * SyQuest EZ drives, the Avatar Shark and the Imation SuperDisk.
 */

#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"

#define j44(a, b)       (((a >> 4) & 0x0f) + (b & 0xf0))
#define j53(a, b)       (((a >> 3) & 0x1f) + ((b << 4) & 0xe0))

static int epatc8;

module_param(epatc8, int, 0);
MODULE_PARM_DESC(epatc8,
                 "support for the Shuttle EP1284 chip, "
                 "used in any recent Imation SuperDisk (LS-120) drive.");

/*
 * cont =  0   IDE register file
 * cont =  1   IDE control registers
 * cont =  2   internal EPAT registers
 */
static int cont_map[3] = { 0x18, 0x10, 0 };

static void epat_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:
        case 2:
                w0(0x60+r); w2(1); w0(val); w2(4);
                break;
        case 3:
        case 4:
        case 5:
                w3(0x40+r); w4(val);
                break;
        }
}

static int epat_read_regr(struct pi_adapter *pi, int cont, int regr)
{
        int  a, b, r;

        r = regr + cont_map[cont];

        switch (pi->mode) {

        case 0:
                w0(r); w2(1); w2(3);
                a = r1(); w2(4); b = r1();
                return j44(a, b);
        case 1:
                w0(0x40+r); w2(1); w2(4);
                a = r1(); b = r2(); w0(0xff);
                return j53(a, b);
        case 2:
                w0(0x20+r); w2(1); w2(0x25);
                a = r0(); w2(4);
                return a;
        case 3:
        case 4:
        case 5:
                w3(r); w2(0x24); a = r4(); w2(4);
                return a;
        }

        return -1;      /* never gets here */
}

static void epat_read_block(struct pi_adapter *pi, char *buf, int count)
{
        int  k, ph, a, b;

        switch (pi->mode) {

        case 0:
                w0(7); w2(1); w2(3); w0(0xff);
                ph = 0;
                for (k = 0; k < count; k++) {
                        if (k == count-1)
                                w0(0xfd);
                        w2(6 + ph); a = r1();
                        if (a & 8) {
                                b = a;
                        } else {
                                w2(4+ph); b = r1();
                        }
                        buf[k] = j44(a, b);
                        ph =  1 - ph;
                }
                w0(0); w2(4);
                break;

        case 1:
                w0(0x47); w2(1); w2(5); w0(0xff);
                ph = 0;
                for (k = 0; k < count; k++) {
                        if (k == count - 1)
                                w0(0xfd);
                        w2(4 + ph);
                        a = r1(); b = r2();
                        buf[k] = j53(a, b);
                        ph = 1 - ph;
                }
                w0(0); w2(4);
                break;

        case 2:
                w0(0x27); w2(1); w2(0x25); w0(0);
                ph = 0;
                for (k = 0; k < count - 1; k++) {
                        w2(0x24 + ph);
                        buf[k] = r0();
                        ph = 1 - ph;
                }
                w2(0x26); w2(0x27);
                buf[count - 1] = r0();
                w2(0x25); w2(4);
                break;

        case 3:
                w3(0x80); w2(0x24);
                for (k = 0; k < count - 1; k++)
                        buf[k] = r4();
                w2(4); w3(0xa0); w2(0x24);
                buf[count - 1] = r4();
                w2(4);
                break;

        case 4:
                w3(0x80); w2(0x24);
                for (k = 0; k < count / 2 - 1; k++)
                        ((u16 *)buf)[k] = r4w();
                buf[count - 2] = r4();
                w2(4); w3(0xa0); w2(0x24);
                buf[count - 1] = r4();
                w2(4);
                break;

        case 5:
                w3(0x80); w2(0x24);
                for (k = 0; k < count / 4 - 1; k++)
                        ((u32 *)buf)[k] = r4l();
                for (k = count - 4; k < count - 1; k++)
                        buf[k] = r4();
                w2(4); w3(0xa0); w2(0x24);
                buf[count - 1] = r4();
                w2(4);
                break;
        }
}

static void epat_write_block(struct pi_adapter *pi, char *buf, int count)
{
        int ph, k;

        switch (pi->mode) {
        case 0:
        case 1:
        case 2:
                w0(0x67); w2(1); w2(5);
                ph = 0;
                for (k = 0; k < count; k++) {
                        w0(buf[k]);
                        w2(4 + ph);
                        ph = 1 - ph;
                }
                w2(7); w2(4);
                break;
        case 3:
                w3(0xc0);
                for (k = 0; k < count; k++)
                        w4(buf[k]);
                w2(4);
                break;
        case 4:
                w3(0xc0);
                for (k = 0; k < count / 2; k++)
                        w4w(((u16 *)buf)[k]);
                w2(4);
                break;
        case 5:
                w3(0xc0);
                for (k = 0; k < count / 4; k++)
                        w4l(((u32 *)buf)[k]);
                w2(4);
                break;
        }
}

/* these macros access the EPAT registers in native addressing */

#define WR(r, v)        epat_write_regr(pi, 2, r, v)
#define RR(r)           epat_read_regr(pi, 2, r)

/* and these access the IDE task file */

#define WRi(r, v)       epat_write_regr(pi, 0, r, v)
#define RRi(r)          epat_read_regr(pi, 0, r)

/* FIXME:  the CPP stuff should be fixed to handle multiple EPATs on a chain */

#define CPP(x)                                  \
        do {                                    \
                w2(4); w0(0x22); w0(0xaa);      \
                w0(0x55); w0(0); w0(0xff);      \
                w0(0x87); w0(0x78); w0(x);      \
                w2(4); w2(5); w2(4); w0(0xff);  \
        } while (0)

static void epat_connect(struct pi_adapter *pi)
{
        pi->saved_r0 = r0();
        pi->saved_r2 = r2();

        /* Initialize the chip */
        CPP(0);

        if (epatc8) {
                CPP(0x40); CPP(0xe0);
                w0(0); w2(1); w2(4);
                WR(0x8, 0x12);
                WR(0xc, 0x14);
                WR(0x12, 0x10);
                WR(0xe, 0xf);
                WR(0xf, 4);
                /* WR(0xe,0xa);WR(0xf,4); */
                WR(0xe, 0xd);
                WR(0xf, 0);
                /* CPP(0x30); */
        }

        /* Connect to the chip */
        CPP(0xe0);
        w0(0); w2(1); w2(4); /* Idle into SPP */
        if (pi->mode >= 3) {
                w0(0); w2(1); w2(4); w2(0xc);
                /* Request EPP */
                w0(0x40); w2(6); w2(7); w2(4); w2(0xc); w2(4);
        }

        if (!epatc8) {
                WR(8, 0x10);
                WR(0xc, 0x14);
                WR(0xa, 0x38);
                WR(0x12, 0x10);
        }
}

static void epat_disconnect(struct pi_adapter *pi)
{
        CPP(0x30);
        w0(pi->saved_r0);
        w2(pi->saved_r2);
}

static int epat_test_proto(struct pi_adapter *pi)
{
        int k, j, f, cc;
        int e[2] = { 0, 0 };
        char scratch[512];

        epat_connect(pi);
        cc = RR(0xd);
        epat_disconnect(pi);

        epat_connect(pi);
        for (j=0;j<2;j++) {
                WRi(6, 0xa0 + j * 0x10);
                for (k = 0; k < 256; k++) {
                        WRi(2, k ^ 0xaa);
                        WRi(3, k ^ 0x55);
                        if (RRi(2) != (k ^ 0xaa))
                                e[j]++;
                }
        }
        epat_disconnect(pi);

        f = 0;
        epat_connect(pi);
        WR(0x13, 1); WR(0x13, 0); WR(0xa, 0x11);
        epat_read_block(pi, scratch, 512);

        for (k = 0; k < 256; k++) {
                if ((scratch[2 * k] & 0xff) != k)
                        f++;
                if ((scratch[2 * k + 1] & 0xff) != 0xff - k)
                        f++;
        }
        epat_disconnect(pi);

        dev_dbg(&pi->dev,
                "epat: port 0x%x, mode %d, ccr %x, test=(%d,%d,%d)\n",
                pi->port, pi->mode, cc, e[0], e[1], f);

        return (e[0] && e[1]) || f;
}

static void epat_log_adapter(struct pi_adapter *pi)
{
        int ver;
        char *mode_string[6] =
                { "4-bit", "5/3", "8-bit", "EPP-8", "EPP-16", "EPP-32" };

        epat_connect(pi);
        WR(0xa, 0x38);          /* read the version code */
        ver = RR(0xb);
        epat_disconnect(pi);

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

static struct pi_protocol epat = {
        .owner          = THIS_MODULE,
        .name           = "epat",
        .max_mode       = 6,
        .epp_first      = 3,
        .default_delay  = 1,
        .max_units      = 1,
        .write_regr     = epat_write_regr,
        .read_regr      = epat_read_regr,
        .write_block    = epat_write_block,
        .read_block     = epat_read_block,
        .connect        = epat_connect,
        .disconnect     = epat_disconnect,
        .test_proto     = epat_test_proto,
        .log_adapter    = epat_log_adapter,
};

static int __init epat_init(void)
{
#ifdef CONFIG_PATA_PARPORT_EPATC8
        epatc8 = 1;
#endif
        return pata_parport_register_driver(&epat);
}

static void __exit epat_exit(void)
{
        pata_parport_unregister_driver(&epat);
}

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Grant R. Guenther <grant@torque.net>");
MODULE_DESCRIPTION("Shuttle Technologies EPAT parallel port IDE adapter "
                   "protocol driver");
module_init(epat_init)
module_exit(epat_exit)