// SPDX-License-Identifier: GPL-2.0

/*
 * Atari Falcon PATA controller driver
 *
 * Copyright (c) 2016 Samsung Electronics Co., Ltd.
 *		http://www.samsung.com
 *
 * Based on falconide.c:
 *
 *     Created 12 Jul 1997 by Geert Uytterhoeven
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/blkdev.h>
#include <linux/delay.h>
#include <scsi/scsi_host.h>
#include <scsi/scsi_cmnd.h>
#include <linux/ata.h>
#include <linux/libata.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/platform_device.h>

#include <asm/setup.h>
#include <asm/atarihw.h>
#include <asm/atariints.h>
#include <asm/atari_stdma.h>

#define DRV_NAME "pata_falcon"
#define DRV_VERSION "0.1.0"

static int pata_falcon_swap_mask;

module_param_named(data_swab, pata_falcon_swap_mask, int, 0444);
MODULE_PARM_DESC(data_swab, "Data byte swap enable/disable bitmap (0x1==drive1, 0x2==drive2, 0x4==drive3, 0x8==drive4, default==0)");

static const struct scsi_host_template pata_falcon_sht = {
	ATA_PIO_SHT(DRV_NAME),
};

static unsigned int pata_falcon_data_xfer(struct ata_queued_cmd *qc,
					  unsigned char *buf,
					  unsigned int buflen, int rw)
{
	struct ata_device *dev = qc->dev;
	struct ata_port *ap = dev->link->ap;
	void __iomem *data_addr = ap->ioaddr.data_addr;
	unsigned int words = buflen >> 1;
	struct scsi_cmnd *cmd = qc->scsicmd;
	bool swap = 1;

	if (dev->class == ATA_DEV_ATA && cmd &&
	    !blk_rq_is_passthrough(scsi_cmd_to_rq(cmd)))
		swap = (uintptr_t)ap->private_data & BIT(dev->devno);

	/* Transfer multiple of 2 bytes */
	if (rw == READ) {
		if (swap)
			raw_insw_swapw(data_addr, (u16 *)buf, words);
		else
			raw_insw(data_addr, (u16 *)buf, words);
	} else {
		if (swap)
			raw_outsw_swapw(data_addr, (u16 *)buf, words);
		else
			raw_outsw(data_addr, (u16 *)buf, words);
	}

	/* Transfer trailing byte, if any. */
	if (unlikely(buflen & 0x01)) {
		unsigned char pad[2] = { };

		/* Point buf to the tail of buffer */
		buf += buflen - 1;

		if (rw == READ) {
			if (swap)
				raw_insw_swapw(data_addr, (u16 *)pad, 1);
			else
				raw_insw(data_addr, (u16 *)pad, 1);
			*buf = pad[0];
		} else {
			pad[0] = *buf;
			if (swap)
				raw_outsw_swapw(data_addr, (u16 *)pad, 1);
			else
				raw_outsw(data_addr, (u16 *)pad, 1);
		}
		words++;
	}

	return words << 1;
}

/*
 * Provide our own set_mode() as we don't want to change anything that has
 * already been configured..
 */
static int pata_falcon_set_mode(struct ata_link *link,
				struct ata_device **unused)
{
	struct ata_device *dev;

	ata_for_each_dev(dev, link, ENABLED) {
		/* We don't really care */
		dev->pio_mode = dev->xfer_mode = XFER_PIO_0;
		dev->xfer_shift = ATA_SHIFT_PIO;
		dev->flags |= ATA_DFLAG_PIO;
		ata_dev_info(dev, "configured for PIO\n");
	}
	return 0;
}

static struct ata_port_operations pata_falcon_ops = {
	.inherits	= &ata_sff_port_ops,
	.sff_data_xfer	= pata_falcon_data_xfer,
	.cable_detect	= ata_cable_unknown,
	.set_mode	= pata_falcon_set_mode,
};

static int pata_falcon_init_one(struct platform_device *pdev)
{
	struct resource *base_mem_res, *ctl_mem_res;
	struct resource *base_res, *ctl_res, *irq_res;
	struct ata_host *host;
	struct ata_port *ap;
	void __iomem *base, *ctl_base;
	int mask_shift = 0; /* Q40 & Falcon default */
	int irq = 0, io_offset = 1, reg_shift = 2; /* Falcon defaults */

	dev_info(&pdev->dev, "Atari Falcon and Q40/Q60 PATA controller\n");

	base_res = platform_get_resource(pdev, IORESOURCE_IO, 0);
	if (base_res && !devm_request_region(&pdev->dev, base_res->start,
					   resource_size(base_res), DRV_NAME)) {
		dev_err(&pdev->dev, "resources busy\n");
		return -EBUSY;
	}

	ctl_res = platform_get_resource(pdev, IORESOURCE_IO, 1);
	if (ctl_res && !devm_request_region(&pdev->dev, ctl_res->start,
					    resource_size(ctl_res), DRV_NAME)) {
		dev_err(&pdev->dev, "resources busy\n");
		return -EBUSY;
	}

	base_mem_res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (!base_mem_res)
		return -ENODEV;
	if (!devm_request_mem_region(&pdev->dev, base_mem_res->start,
				     resource_size(base_mem_res), DRV_NAME)) {
		dev_err(&pdev->dev, "resources busy\n");
		return -EBUSY;
	}

	ctl_mem_res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
	if (!ctl_mem_res)
		return -ENODEV;

	/* allocate host */
	host = ata_host_alloc(&pdev->dev, 1);
	if (!host)
		return -ENOMEM;
	ap = host->ports[0];

	ap->ops = &pata_falcon_ops;
	ap->pio_mask = ATA_PIO4;
	ap->flags |= ATA_FLAG_SLAVE_POSS | ATA_FLAG_NO_IORDY;

	/* N.B. this assumes data_addr will be used for word-sized I/O only */
	ap->ioaddr.data_addr = (void __iomem *)base_mem_res->start;

	if (base_res) {		/* only Q40 has IO resources */
		io_offset = 0x10000;
		reg_shift = 0;
		base = (void __iomem *)base_res->start;
		ctl_base = (void __iomem *)ctl_res->start;
	} else {
		base = (void __iomem *)base_mem_res->start;
		ctl_base = (void __iomem *)ctl_mem_res->start;
	}

	ap->ioaddr.error_addr	= base + io_offset + (1 << reg_shift);
	ap->ioaddr.feature_addr	= base + io_offset + (1 << reg_shift);
	ap->ioaddr.nsect_addr	= base + io_offset + (2 << reg_shift);
	ap->ioaddr.lbal_addr	= base + io_offset + (3 << reg_shift);
	ap->ioaddr.lbam_addr	= base + io_offset + (4 << reg_shift);
	ap->ioaddr.lbah_addr	= base + io_offset + (5 << reg_shift);
	ap->ioaddr.device_addr	= base + io_offset + (6 << reg_shift);
	ap->ioaddr.status_addr	= base + io_offset + (7 << reg_shift);
	ap->ioaddr.command_addr	= base + io_offset + (7 << reg_shift);

	ap->ioaddr.altstatus_addr	= ctl_base + io_offset;
	ap->ioaddr.ctl_addr		= ctl_base + io_offset;

	ata_port_desc(ap, "cmd %px ctl %px data %px",
		      base, ctl_base, ap->ioaddr.data_addr);

	if (pdev->id > 0)
		mask_shift = 2;
	ap->private_data = (void *)(uintptr_t)(pata_falcon_swap_mask >> mask_shift);

	irq_res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
	if (irq_res && irq_res->start > 0) {
		irq = irq_res->start;
	} else {
		ap->flags |= ATA_FLAG_PIO_POLLING;
		ata_port_desc(ap, "no IRQ, using PIO polling");
	}

	/* activate */
	return ata_host_activate(host, irq, irq ? ata_sff_interrupt : NULL,
				 IRQF_SHARED, &pata_falcon_sht);
}

static void pata_falcon_remove_one(struct platform_device *pdev)
{
	struct ata_host *host = platform_get_drvdata(pdev);

	ata_host_detach(host);
}

static struct platform_driver pata_falcon_driver = {
	.probe = pata_falcon_init_one,
	.remove = pata_falcon_remove_one,
	.driver = {
		.name	= "atari-falcon-ide",
	},
};

module_platform_driver(pata_falcon_driver);

MODULE_AUTHOR("Bartlomiej Zolnierkiewicz");
MODULE_DESCRIPTION("low-level driver for Atari Falcon PATA");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:atari-falcon-ide");
MODULE_VERSION(DRV_VERSION);