// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * (c) 1996-1998  Grant R. Guenther <grant@torque.net>
 *
 * frpw.c is a low-level protocol driver for the Freecom "Power" parallel port
 * IDE adapter.
 *
 * Some applications of this adapter may require a "printer" reset prior to
 * loading the driver.  This can be done by loading and unloading the "lp"
 * driver, or it can be done by this driver if you define FRPW_HARD_RESET.
 * The latter is not recommended as it may upset devices on other ports.
 */

#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 cec4		w2(0xc);w2(0xe);w2(0xe);w2(0xc);w2(4);w2(4);w2(4);
#define j44(l,h)	(((l>>4)&0x0f)|(h&0xf0))

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

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

	r = regr + cont_map[cont];

	w2(4);
	w0(r); cec4;
	w2(6); l = r1();
	w2(4); h = r1();
	w2(4);

	return j44(l, h);
}

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

	w2(4); w0(r); cec4;
	w0(val);
	w2(5); w2(7); w2(5); w2(4);
}

static void frpw_read_block_int(struct pi_adapter *pi, char *buf, int count,
				int regr)
{
	int h, l, k, ph;

	switch (pi->mode) {
	case 0:
		w2(4); w0(regr); cec4;
		for (k = 0; k < count; k++) {
			w2(6); l = r1();
			w2(4); h = r1();
			buf[k] = j44(l, h);
		}
		w2(4);
		break;

	case 1:
		ph = 2;
		w2(4); w0(regr + 0xc0); cec4;
		w0(0xff);
		for (k = 0; k < count; k++) {
			w2(0xa4 + ph);
			buf[k] = r0();
			ph = 2 - ph;
		}
		w2(0xac); w2(0xa4); w2(4);
		break;

	case 2:
		w2(4); w0(regr + 0x80); cec4;
		for (k = 0; k < count; k++)
			buf[k] = r4();
		w2(0xac); w2(0xa4);
		w2(4);
		break;

	case 3:
		w2(4); w0(regr + 0x80); cec4;
		for (k = 0; k < count - 2; k++)
			buf[k] = r4();
		w2(0xac); w2(0xa4);
		buf[count - 2] = r4();
		buf[count - 1] = r4();
		w2(4);
		break;

	case 4:
		w2(4); w0(regr + 0x80); cec4;
		for (k = 0; k < count / 2 - 1; k++)
			((u16 *)buf)[k] = r4w();
		w2(0xac); w2(0xa4);
		buf[count - 2] = r4();
		buf[count - 1] = r4();
		w2(4);
		break;

	case 5:
		w2(4); w0(regr + 0x80); cec4;
		for (k = 0; k < count / 4 - 1; k++)
			((u32 *)buf)[k] = r4l();
		buf[count - 4] = r4();
		buf[count - 3] = r4();
		w2(0xac); w2(0xa4);
		buf[count - 2] = r4();
		buf[count - 1] = r4();
		w2(4);
		break;
        }
}

static void frpw_read_block(struct pi_adapter *pi, char *buf, int count)
{
	frpw_read_block_int(pi, buf, count, 0x08);
}

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

	switch (pi->mode) {
	case 0:
	case 1:
	case 2:
		w2(4); w0(8); cec4; w2(5);
		for (k = 0; k < count; k++) {
			w0(buf[k]);
			w2(7); w2(5);
		}
		w2(4);
		break;

	case 3:
		w2(4); w0(0xc8); cec4; w2(5);
		for (k = 0; k < count; k++)
			w4(buf[k]);
		w2(4);
		break;

	case 4:
		w2(4); w0(0xc8); cec4; w2(5);
		for (k = 0; k < count / 2; k++)
			w4w(((u16 *)buf)[k]);
		w2(4);
		break;

	case 5:
		w2(4); w0(0xc8); cec4; w2(5);
		for (k = 0; k < count / 4; k++)
			w4l(((u32 *)buf)[k]);
		w2(4);
		break;
	}
}

static void frpw_connect(struct pi_adapter *pi)
{
	pi->saved_r0 = r0();
	pi->saved_r2 = r2();
	w2(4);
}

static void frpw_disconnect(struct pi_adapter *pi)
{
	w2(4); w0(0x20); cec4;
	w0(pi->saved_r0);
	w2(pi->saved_r2);
}

/*
 * Stub logic to see if PNP string is available - used to distinguish
 * between the Xilinx and ASIC implementations of the Freecom adapter.
 * returns chip_type:   0 = Xilinx, 1 = ASIC
 */
static int frpw_test_pnp(struct pi_adapter *pi)
{
	int olddelay, a, b;

#ifdef FRPW_HARD_RESET
        w0(0); w2(8); udelay(50); w2(0xc);   /* parallel bus reset */
        mdelay(1500);
#endif

	olddelay = pi->delay;
	pi->delay = 10;

	pi->saved_r0 = r0();
        pi->saved_r2 = r2();

	w2(4); w0(4); w2(6); w2(7);
	a = r1() & 0xff; w2(4); b = r1() & 0xff;
	w2(0xc); w2(0xe); w2(4);

	pi->delay = olddelay;
        w0(pi->saved_r0);
        w2(pi->saved_r2);

	return ((~a & 0x40) && (b & 0x40));
}

/*
 * We use the pi->private to remember the result of the PNP test.
 * To make this work, private = port*2 + chip.  Yes, I know it's a hack :-(
 */
static int frpw_test_proto(struct pi_adapter *pi)
{
	int j, k, r;
	int e[2] = { 0, 0 };
	char scratch[512];

	if ((pi->private >> 1) != pi->port)
		pi->private = frpw_test_pnp(pi) + 2*pi->port;

	if (((pi->private & 0x1) == 0) && (pi->mode > 2)) {
		dev_dbg(&pi->dev,
			"frpw: Xilinx does not support mode %d\n", pi->mode);
		return 1;
	}

	if (((pi->private & 0x1) == 1) && (pi->mode == 2)) {
		dev_dbg(&pi->dev, "frpw: ASIC does not support mode 2\n");
		return 1;
	}

	frpw_connect(pi);
	for (j = 0; j < 2; j++) {
		frpw_write_regr(pi, 0, 6, 0xa0 + j * 0x10);
		for (k = 0; k < 256; k++) {
			frpw_write_regr(pi, 0, 2, k ^ 0xaa);
			frpw_write_regr(pi, 0, 3, k ^ 0x55);
			if (frpw_read_regr(pi, 0, 2) != (k ^ 0xaa))
				e[j]++;
		}
	}
	frpw_disconnect(pi);

	frpw_connect(pi);
	frpw_read_block_int(pi, scratch, 512, 0x10);
	r = 0;
	for (k = 0; k < 128; k++) {
		if (scratch[k] != k)
			r++;
	}
	frpw_disconnect(pi);

	dev_dbg(&pi->dev,
		"frpw: port 0x%x, chip %ld, mode %d, test=(%d,%d,%d)\n",
		pi->port, (pi->private%2), pi->mode, e[0], e[1], r);

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

static void frpw_log_adapter(struct pi_adapter *pi)

{
	char *mode[6] = { "4-bit", "8-bit", "EPP", "EPP-8", "EPP-16", "EPP-32"};

	dev_info(&pi->dev,
		 "Freecom (%s) adapter at 0x%x, mode %d (%s), delay %d\n",
		 ((pi->private & 0x1) == 0) ? "Xilinx" : "ASIC",
		 pi->port, pi->mode, mode[pi->mode], pi->delay);
}

static struct pi_protocol frpw = {
	.owner		= THIS_MODULE,
	.name		= "frpw",
	.max_mode	= 6,
	.epp_first	= 2,
	.default_delay	= 2,
	.max_units	= 1,
	.write_regr	= frpw_write_regr,
	.read_regr	= frpw_read_regr,
	.write_block	= frpw_write_block,
	.read_block	= frpw_read_block,
	.connect	= frpw_connect,
	.disconnect	= frpw_disconnect,
	.test_proto	= frpw_test_proto,
	.log_adapter	= frpw_log_adapter,
};

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