// 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);