// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * (c) 1997-1998  Grant R. Guenther <grant@torque.net>
 *
 * epia.c is a low-level protocol driver for Shuttle Technologies
 * EPIA parallel to IDE adapter chip.  This device is now obsolete
 * and has been replaced with the EPAT chip, which is supported
 * by epat.c, however, some devices based on EPIA are still
 * available.
 */

#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 on port 1, 8-bit writes
 *              1  5/3 reads on ports 1 & 2, 8-bit writes
 *              2  8-bit reads and writes
 *              3  8-bit EPP mode
 *              4  16-bit EPP
 *              5  32-bit EPP
 */

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

/*
 * cont =  0   IDE register file
 * cont =  1   IDE control registers
 */
static int cont_map[2] = { 0, 0x80 };

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

        regr += cont_map[cont];

        switch (pi->mode)  {
        case 0:
                r = regr ^ 0x39;
                w0(r); w2(1); w2(3); w0(r);
                a = r1(); w2(1); b = r1(); w2(4);
                return j44(a, b);
        case 1:
                r = regr ^ 0x31;
                w0(r); w2(1); w0(r & 0x37);
                w2(3); w2(5); w0(r | 0xf0);
                a = r1(); b = r2(); w2(4);
                return j53(a, b);
        case 2:
                r = regr^0x29;
                w0(r); w2(1); w2(0X21); w2(0x23);
                a = r0(); w2(4);
                return a;
        case 3:
        case 4:
        case 5:
                w3(regr); w2(0x24); a = r4(); w2(4);
                return a;
        }

        return -1;
}

static void epia_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:
                r = regr ^ 0x19;
                w0(r); w2(1); w0(val); w2(3); w2(4);
                break;
        case 3:
        case 4:
        case 5:
                r = regr ^ 0x40;
                w3(r); w4(val); w2(4);
                break;
        }
}

#define WR(r, v)        epia_write_regr(pi, 0, r, v)
#define RR(r)           epia_read_regr(pi, 0, r)

/*
 * The use of register 0x84 is entirely unclear - it seems to control
 * some EPP counters ...  currently we know about 3 different block
 * sizes:  the standard 512 byte reads and writes, 12 byte writes and
 * 2048 byte reads (the last two being used in the CDrom drivers.
 */
static void epia_connect(struct pi_adapter *pi)
{
        pi->saved_r0 = r0();
        pi->saved_r2 = r2();

        w2(4); w0(0xa0); w0(0x50); w0(0xc0); w0(0x30); w0(0xa0); w0(0);
        w2(1); w2(4);
        if (pi->mode >= 3) {
                w0(0xa); w2(1); w2(4); w0(0x82); w2(4); w2(0xc); w2(4);
                w2(0x24); w2(0x26); w2(4);
        }
        WR(0x86, 8);
}

static void epia_disconnect(struct pi_adapter *pi)
{
        /* WR(0x84,0x10); */
        w0(pi->saved_r0);
        w2(1); w2(4);
        w0(pi->saved_r0);
        w2(pi->saved_r2);
}

static void epia_read_block(struct pi_adapter *pi, char *buf, int count)

{
        int k, ph, a, b;

        switch (pi->mode) {
        case 0:
                w0(0x81); w2(1); w2(3); w0(0xc1);
                ph = 1;
                for (k = 0; k < count; k++) {
                        w2(2+ph); a = r1();
                        w2(4+ph); b = r1();
                        buf[k] = j44(a, b);
                        ph = 1 - ph;
                }
                w0(0); w2(4);
                break;
        case 1:
                w0(0x91); w2(1); w0(0x10); w2(3);
                w0(0x51); w2(5); w0(0xd1);
                ph = 1;
                for (k = 0; k < count; k++) {
                        w2(4 + ph);
                        a = r1(); b = r2();
                        buf[k] = j53(a, b);
                        ph = 1 - ph;
                }
                w0(0); w2(4);
                break;
        case 2:
                w0(0x89); w2(1); w2(0x23); w2(0x21);
                ph = 1;
                for (k = 0; k < count; k++) {
                        w2(0x24 + ph);
                        buf[k] = r0();
                        ph = 1 - ph;
                }
                w2(6); w2(4);
                break;
        case 3:
                if (count > 512)
                        WR(0x84, 3);
                w3(0); w2(0x24);
                for (k = 0; k < count; k++)
                        buf[k] = r4();
                w2(4); WR(0x84, 0);
                break;
        case 4:
                if (count > 512)
                        WR(0x84, 3);
                w3(0); w2(0x24);
                for (k = 0; k < count / 2; k++)
                        ((u16 *)buf)[k] = r4w();
                w2(4); WR(0x84, 0);
                break;
        case 5:
                if (count > 512)
                        WR(0x84, 3);
                w3(0); w2(0x24);
                for (k = 0; k < count / 4; k++)
                        ((u32 *)buf)[k] = r4l();
                w2(4); WR(0x84, 0);
                break;
        }
}

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

        switch (pi->mode) {
        case 0:
        case 1:
        case 2:
                w0(0xa1); w2(1); w2(3); w2(1); w2(5);
                ph = 0;  last = 0x8000;
                for (k = 0; k < count; k++) {
                        d = buf[k];
                        if (d != last) {
                                last = d;
                                w0(d);
                        }
                        w2(4 + ph);
                        ph = 1 - ph;
                }
                w2(7); w2(4);
                break;
        case 3:
                if (count < 512)
                        WR(0x84, 1);
                w3(0x40);
                for (k = 0; k < count; k++)
                        w4(buf[k]);
                if (count < 512)
                        WR(0x84, 0);
                break;
        case 4:
                if (count < 512)
                        WR(0x84, 1);
                w3(0x40);
                for (k = 0; k < count / 2; k++)
                        w4w(((u16 *)buf)[k]);
                if (count < 512)
                        WR(0x84, 0);
                break;
        case 5:
                if (count < 512)
                        WR(0x84, 1);
                w3(0x40);
                for (k = 0; k < count / 4; k++)
                        w4l(((u32 *)buf)[k]);
                if (count < 512)
                        WR(0x84, 0);
                break;
        }
}

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

        epia_connect(pi);
        for (j = 0; j < 2; j++) {
                WR(6, 0xa0 + j * 0x10);
                for (k = 0; k < 256; k++) {
                        WR(2, k ^ 0xaa);
                        WR(3, k ^ 0x55);
                        if (RR(2) != (k ^ 0xaa))
                                e[j]++;
                }
                WR(2, 1); WR(3, 1);
        }
        epia_disconnect(pi);

        f = 0;
        epia_connect(pi);
        WR(0x84, 8);
        epia_read_block(pi, scratch, 512);
        for (k = 0; k < 256; k++) {
                if ((scratch[2 * k] & 0xff) != ((k + 1) & 0xff))
                        f++;
                if ((scratch[2 * k + 1] & 0xff) != ((-2 - k) & 0xff))
                        f++;
        }
        WR(0x84, 0);
        epia_disconnect(pi);

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

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


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

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

static struct pi_protocol epia = {
        .owner          = THIS_MODULE,
        .name           = "epia",
        .max_mode       = 6,
        .epp_first      = 3,
        .default_delay  = 1,
        .max_units      = 1,
        .write_regr     = epia_write_regr,
        .read_regr      = epia_read_regr,
        .write_block    = epia_write_block,
        .read_block     = epia_read_block,
        .connect        = epia_connect,
        .disconnect     = epia_disconnect,
        .test_proto     = epia_test_proto,
        .log_adapter    = epia_log_adapter,
};

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Grant R. Guenther <grant@torque.net>");
MODULE_DESCRIPTION("Shuttle Technologies EPIA parallel port IDE adapter "
                   "protocol driver");
module_pata_parport_driver(epia);