// 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);