// 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)