// SPDX-License-Identifier: GPL-2.0-only
#include <linux/types.h>
#include <linux/mm.h>
#include <linux/ioport.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/interrupt.h>
#include <linux/platform_device.h>
#include <linux/dma-mapping.h>
#include <linux/module.h>

#include <asm/page.h>
#include <asm/amigaints.h>
#include <asm/amigahw.h>

#include <scsi/scsi.h>
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_eh.h>
#include <scsi/scsi_tcq.h>
#include "wd33c93.h"
#include "a3000.h"


struct a3000_hostdata {
        struct WD33C93_hostdata wh;
        struct a3000_scsiregs *regs;
        struct device *dev;
};

#define DMA_DIR(d)   ((d == DATA_OUT_DIR) ? DMA_TO_DEVICE : DMA_FROM_DEVICE)

static irqreturn_t a3000_intr(int irq, void *data)
{
        struct Scsi_Host *instance = data;
        struct a3000_hostdata *hdata = shost_priv(instance);
        unsigned int status = hdata->regs->ISTR;
        unsigned long flags;

        if (!(status & ISTR_INT_P))
                return IRQ_NONE;
        if (status & ISTR_INTS) {
                spin_lock_irqsave(instance->host_lock, flags);
                wd33c93_intr(instance);
                spin_unlock_irqrestore(instance->host_lock, flags);
                return IRQ_HANDLED;
        }
        pr_warn("Non-serviced A3000 SCSI-interrupt? ISTR = %02x\n", status);
        return IRQ_NONE;
}

static int dma_setup(struct scsi_cmnd *cmd, int dir_in)
{
        struct scsi_pointer *scsi_pointer = WD33C93_scsi_pointer(cmd);
        unsigned long len = scsi_pointer->this_residual;
        struct Scsi_Host *instance = cmd->device->host;
        struct a3000_hostdata *hdata = shost_priv(instance);
        struct WD33C93_hostdata *wh = &hdata->wh;
        struct a3000_scsiregs *regs = hdata->regs;
        unsigned short cntr = CNTR_PDMD | CNTR_INTEN;
        dma_addr_t addr;

        addr = dma_map_single(hdata->dev, scsi_pointer->ptr,
                              len, DMA_DIR(dir_in));
        if (dma_mapping_error(hdata->dev, addr)) {
                dev_warn(hdata->dev, "cannot map SCSI data block %p\n",
                         scsi_pointer->ptr);
                return 1;
        }
        scsi_pointer->dma_handle = addr;

        /*
         * if the physical address has the wrong alignment, or if
         * physical address is bad, or if it is a write and at the
         * end of a physical memory chunk, then allocate a bounce
         * buffer
         * MSch 20220629 - only wrong alignment tested - bounce
         * buffer returned by kmalloc is guaranteed to be aligned
         */
        if (addr & A3000_XFER_MASK) {
                WARN_ONCE(1, "Invalid alignment for DMA!");
                /* drop useless mapping */
                dma_unmap_single(hdata->dev, scsi_pointer->dma_handle,
                                 scsi_pointer->this_residual,
                                 DMA_DIR(dir_in));

                wh->dma_bounce_len = (scsi_pointer->this_residual + 511) & ~0x1ff;
                wh->dma_bounce_buffer = kmalloc(wh->dma_bounce_len,
                                                GFP_KERNEL);

                /* can't allocate memory; use PIO */
                if (!wh->dma_bounce_buffer) {
                        wh->dma_bounce_len = 0;
                        scsi_pointer->dma_handle = (dma_addr_t) NULL;
                        return 1;
                }

                if (!dir_in) {
                        /* copy to bounce buffer for a write */
                        memcpy(wh->dma_bounce_buffer, scsi_pointer->ptr,
                               scsi_pointer->this_residual);
                }

                addr = dma_map_single(hdata->dev, scsi_pointer->ptr,
                                      len, DMA_DIR(dir_in));
                if (dma_mapping_error(hdata->dev, addr)) {
                        dev_warn(hdata->dev,
                                 "cannot map SCSI data block %p\n",
                                 scsi_pointer->ptr);
                        return 1;
                }
                scsi_pointer->dma_handle = addr;
        }

        /* setup dma direction */
        if (!dir_in)
                cntr |= CNTR_DDIR;

        /* remember direction */
        wh->dma_dir = dir_in;

        regs->CNTR = cntr;

        /* setup DMA *physical* address */
        regs->ACR = addr;

        /* no more cache flush here - dma_map_single() takes care */

        /* start DMA */
        mb();                   /* make sure setup is completed */
        regs->ST_DMA = 1;
        mb();                   /* make sure DMA has started before next IO */

        /* return success */
        return 0;
}

static void dma_stop(struct Scsi_Host *instance, struct scsi_cmnd *SCpnt,
                     int status)
{
        struct scsi_pointer *scsi_pointer = WD33C93_scsi_pointer(SCpnt);
        struct a3000_hostdata *hdata = shost_priv(instance);
        struct WD33C93_hostdata *wh = &hdata->wh;
        struct a3000_scsiregs *regs = hdata->regs;

        /* disable SCSI interrupts */
        unsigned short cntr = CNTR_PDMD;

        if (!wh->dma_dir)
                cntr |= CNTR_DDIR;

        regs->CNTR = cntr;
        mb();                   /* make sure CNTR is updated before next IO */

        /* flush if we were reading */
        if (wh->dma_dir) {
                regs->FLUSH = 1;
                mb();           /* don't allow prefetch */
                while (!(regs->ISTR & ISTR_FE_FLG))
                        barrier();
                mb();           /* no IO until FLUSH is done */
        }

        /* clear a possible interrupt */
        /* I think that this CINT is only necessary if you are
         * using the terminal count features.   HM 7 Mar 1994
         */
        regs->CINT = 1;

        /* stop DMA */
        regs->SP_DMA = 1;
        mb();                   /* make sure DMA is stopped before next IO */

        /* restore the CONTROL bits (minus the direction flag) */
        regs->CNTR = CNTR_PDMD | CNTR_INTEN;
        mb();                   /* make sure CNTR is updated before next IO */

        dma_unmap_single(hdata->dev, scsi_pointer->dma_handle,
                         scsi_pointer->this_residual,
                         DMA_DIR(wh->dma_dir));

        /* copy from a bounce buffer, if necessary */
        if (status && wh->dma_bounce_buffer) {
                if (SCpnt) {
                        if (wh->dma_dir && SCpnt)
                                memcpy(scsi_pointer->ptr, wh->dma_bounce_buffer,
                                       scsi_pointer->this_residual);
                        kfree(wh->dma_bounce_buffer);
                        wh->dma_bounce_buffer = NULL;
                        wh->dma_bounce_len = 0;
                } else {
                        kfree(wh->dma_bounce_buffer);
                        wh->dma_bounce_buffer = NULL;
                        wh->dma_bounce_len = 0;
                }
        }
}

static const struct scsi_host_template amiga_a3000_scsi_template = {
        .module                 = THIS_MODULE,
        .name                   = "Amiga 3000 built-in SCSI",
        .show_info              = wd33c93_show_info,
        .write_info             = wd33c93_write_info,
        .proc_name              = "A3000",
        .queuecommand           = wd33c93_queuecommand,
        .eh_abort_handler       = wd33c93_abort,
        .eh_host_reset_handler  = wd33c93_host_reset,
        .can_queue              = CAN_QUEUE,
        .this_id                = 7,
        .sg_tablesize           = SG_ALL,
        .cmd_per_lun            = CMD_PER_LUN,
        .cmd_size               = sizeof(struct scsi_pointer),
};

static int __init amiga_a3000_scsi_probe(struct platform_device *pdev)
{
        struct resource *res;
        struct Scsi_Host *instance;
        int error;
        struct a3000_scsiregs *regs;
        wd33c93_regs wdregs;
        struct a3000_hostdata *hdata;

        if (dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(32))) {
                dev_warn(&pdev->dev, "cannot use 32 bit DMA\n");
                return -ENODEV;
        }

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (!res)
                return -ENODEV;

        if (!request_mem_region(res->start, resource_size(res), "wd33c93"))
                return -EBUSY;

        instance = scsi_host_alloc(&amiga_a3000_scsi_template,
                                   sizeof(struct a3000_hostdata));
        if (!instance) {
                error = -ENOMEM;
                goto fail_alloc;
        }

        instance->irq = IRQ_AMIGA_PORTS;

        regs = ZTWO_VADDR(res->start);
        regs->DAWR = DAWR_A3000;

        wdregs.SASR = &regs->SASR;
        wdregs.SCMD = &regs->SCMD;

        hdata = shost_priv(instance);
        hdata->dev = &pdev->dev;
        hdata->wh.no_sync = 0xff;
        hdata->wh.fast = 0;
        hdata->wh.dma_mode = CTRL_DMA;
        hdata->regs = regs;

        wd33c93_init(instance, wdregs, dma_setup, dma_stop, WD33C93_FS_12_15);
        error = request_irq(IRQ_AMIGA_PORTS, a3000_intr, IRQF_SHARED,
                            "A3000 SCSI", instance);
        if (error)
                goto fail_irq;

        regs->CNTR = CNTR_PDMD | CNTR_INTEN;

        error = scsi_add_host(instance, NULL);
        if (error)
                goto fail_host;

        platform_set_drvdata(pdev, instance);

        scsi_scan_host(instance);
        return 0;

fail_host:
        free_irq(IRQ_AMIGA_PORTS, instance);
fail_irq:
        scsi_host_put(instance);
fail_alloc:
        release_mem_region(res->start, resource_size(res));
        return error;
}

static void __exit amiga_a3000_scsi_remove(struct platform_device *pdev)
{
        struct Scsi_Host *instance = platform_get_drvdata(pdev);
        struct a3000_hostdata *hdata = shost_priv(instance);
        struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);

        hdata->regs->CNTR = 0;
        scsi_remove_host(instance);
        free_irq(IRQ_AMIGA_PORTS, instance);
        scsi_host_put(instance);
        release_mem_region(res->start, resource_size(res));
}

/*
 * amiga_a3000_scsi_remove() lives in .exit.text. For drivers registered via
 * module_platform_driver_probe() this is ok because they cannot get unbound at
 * runtime. So mark the driver struct with __refdata to prevent modpost
 * triggering a section mismatch warning.
 */
static struct platform_driver amiga_a3000_scsi_driver __refdata = {
        .remove = __exit_p(amiga_a3000_scsi_remove),
        .driver = {
                .name = "amiga-a3000-scsi",
        },
};

module_platform_driver_probe(amiga_a3000_scsi_driver, amiga_a3000_scsi_probe);

MODULE_DESCRIPTION("Amiga 3000 built-in SCSI");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:amiga-a3000-scsi");