// 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_new = __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");