drivers/scsi/mac_esp.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /* mac_esp.c: ESP front-end for Macintosh Quadra systems.
  *
  * Adapted from jazz_esp.c and the old mac_esp.c.
  *
  * The pseudo DMA algorithm is based on the one used in NetBSD.
  * See sys/arch/mac68k/obio/esp.c for some background information.
  *
  * Copyright (C) 2007-2008 Finn Thain
  */

 #include <linux/kernel.h>
 #include <linux/types.h>
 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/interrupt.h>
 #include <linux/platform_device.h>
 #include <linux/dma-mapping.h>
 #include <linux/scatterlist.h>
 #include <linux/delay.h>
 #include <linux/io.h>
 #include <linux/nubus.h>
 #include <linux/slab.h>

 #include <asm/irq.h>
 #include <asm/dma.h>
 #include <asm/macints.h>
 #include <asm/macintosh.h>
 #include <asm/mac_via.h>

 #include <scsi/scsi_host.h>

 #include "esp_scsi.h"

 #define DRV_MODULE_NAME     "mac_esp"
 #define PFX                 DRV_MODULE_NAME ": "
 #define DRV_VERSION         "1.000"
 #define DRV_MODULE_RELDATE  "Sept 15, 2007"

 #define MAC_ESP_IO_BASE          0x50F00000
 #define MAC_ESP_REGS_QUADRA      (MAC_ESP_IO_BASE + 0x10000)
 #define MAC_ESP_REGS_QUADRA2     (MAC_ESP_IO_BASE + 0xF000)
 #define MAC_ESP_REGS_QUADRA3     (MAC_ESP_IO_BASE + 0x18000)
 #define MAC_ESP_REGS_SPACING     0x402
 #define MAC_ESP_PDMA_REG         0xF9800024
 #define MAC_ESP_PDMA_REG_SPACING 0x4
 #define MAC_ESP_PDMA_IO_OFFSET   0x100

 #define esp_read8(REG)		mac_esp_read8(esp, REG)
 #define esp_write8(VAL, REG)	mac_esp_write8(esp, VAL, REG)

 struct mac_esp_priv {
 	struct esp *esp;
 	void __iomem *pdma_regs;
 	void __iomem *pdma_io;
 };
 static struct esp *esp_chips[2];
 static DEFINE_SPINLOCK(esp_chips_lock);

 #define MAC_ESP_GET_PRIV(esp) ((struct mac_esp_priv *) \
 			       dev_get_drvdata((esp)->dev))

 static inline void mac_esp_write8(struct esp *esp, u8 val, unsigned long reg)
 {
 	nubus_writeb(val, esp->regs + reg * 16);
 }

 static inline u8 mac_esp_read8(struct esp *esp, unsigned long reg)
 {
 	return nubus_readb(esp->regs + reg * 16);
 }

 static void mac_esp_reset_dma(struct esp *esp)
 {
 	/* Nothing to do. */
 }

 static void mac_esp_dma_drain(struct esp *esp)
 {
 	/* Nothing to do. */
 }

 static void mac_esp_dma_invalidate(struct esp *esp)
 {
 	/* Nothing to do. */
 }

 static int mac_esp_dma_error(struct esp *esp)
 {
 	return esp->send_cmd_error;
 }

 static inline int mac_esp_wait_for_empty_fifo(struct esp *esp)
 {
 	int i = 500000;

 	do {
 		if (!(esp_read8(ESP_FFLAGS) & ESP_FF_FBYTES))
 			return 0;

 		if (esp_read8(ESP_STATUS) & ESP_STAT_INTR)
 			return 1;

 		udelay(2);
 	} while (--i);

 	printk(KERN_ERR PFX "FIFO is not empty (sreg %02x)\n",
 	       esp_read8(ESP_STATUS));
 	esp->send_cmd_error = 1;
 	return 1;
 }

 static inline int mac_esp_wait_for_dreq(struct esp *esp)
 {
 	struct mac_esp_priv *mep = MAC_ESP_GET_PRIV(esp);
 	int i = 500000;

 	do {
 		if (mep->pdma_regs == NULL) {
 			if (via2_scsi_drq_pending())
 				return 0;
 		} else {
 			if (nubus_readl(mep->pdma_regs) & 0x200)
 				return 0;
 		}

 		if (esp_read8(ESP_STATUS) & ESP_STAT_INTR)
 			return 1;

 		udelay(2);
 	} while (--i);

 	printk(KERN_ERR PFX "PDMA timeout (sreg %02x)\n",
 	       esp_read8(ESP_STATUS));
 	esp->send_cmd_error = 1;
 	return 1;
 }

 #define MAC_ESP_PDMA_LOOP(operands) \
 	asm volatile ( \
 	     "       tstw %1                   \n" \
 	     "       jbeq 20f                  \n" \
 	     "1:     movew " operands "        \n" \
 	     "2:     movew " operands "        \n" \
 	     "3:     movew " operands "        \n" \
 	     "4:     movew " operands "        \n" \
 	     "5:     movew " operands "        \n" \
 	     "6:     movew " operands "        \n" \
 	     "7:     movew " operands "        \n" \
 	     "8:     movew " operands "        \n" \
 	     "9:     movew " operands "        \n" \
 	     "10:    movew " operands "        \n" \
 	     "11:    movew " operands "        \n" \
 	     "12:    movew " operands "        \n" \
 	     "13:    movew " operands "        \n" \
 	     "14:    movew " operands "        \n" \
 	     "15:    movew " operands "        \n" \
 	     "16:    movew " operands "        \n" \
 	     "       subqw #1,%1               \n" \
 	     "       jbne 1b                   \n" \
 	     "20:    tstw %2                   \n" \
 	     "       jbeq 30f                  \n" \
 	     "21:    movew " operands "        \n" \
 	     "       subqw #1,%2               \n" \
 	     "       jbne 21b                  \n" \
 	     "30:    tstw %3                   \n" \
 	     "       jbeq 40f                  \n" \
 	     "31:    moveb " operands "        \n" \
 	     "32:    nop                       \n" \
 	     "40:                              \n" \
 	     "                                 \n" \
 	     "       .section __ex_table,\"a\" \n" \
 	     "       .align  4                 \n" \
 	     "       .long   1b,40b            \n" \
 	     "       .long   2b,40b            \n" \
 	     "       .long   3b,40b            \n" \
 	     "       .long   4b,40b            \n" \
 	     "       .long   5b,40b            \n" \
 	     "       .long   6b,40b            \n" \
 	     "       .long   7b,40b            \n" \
 	     "       .long   8b,40b            \n" \
 	     "       .long   9b,40b            \n" \
 	     "       .long  10b,40b            \n" \
 	     "       .long  11b,40b            \n" \
 	     "       .long  12b,40b            \n" \
 	     "       .long  13b,40b            \n" \
 	     "       .long  14b,40b            \n" \
 	     "       .long  15b,40b            \n" \
 	     "       .long  16b,40b            \n" \
 	     "       .long  21b,40b            \n" \
 	     "       .long  31b,40b            \n" \
 	     "       .long  32b,40b            \n" \
 	     "       .previous                 \n" \
 	     : "+a" (addr), "+r" (count32), "+r" (count2) \
 	     : "g" (count1), "a" (mep->pdma_io))

 static void mac_esp_send_pdma_cmd(struct esp *esp, u32 addr, u32 esp_count,
 				  u32 dma_count, int write, u8 cmd)
 {
 	struct mac_esp_priv *mep = MAC_ESP_GET_PRIV(esp);

 	esp->send_cmd_error = 0;

 	if (!write)
 		scsi_esp_cmd(esp, ESP_CMD_FLUSH);

 	esp_write8((esp_count >> 0) & 0xFF, ESP_TCLOW);
 	esp_write8((esp_count >> 8) & 0xFF, ESP_TCMED);

 	scsi_esp_cmd(esp, cmd);

 	do {
 		unsigned int count32 = esp_count >> 5;
 		unsigned int count2 = (esp_count & 0x1F) >> 1;
 		unsigned int count1 = esp_count & 1;
 		unsigned int start_addr = addr;

 		if (mac_esp_wait_for_dreq(esp))
 			break;

 		if (write) {
 			MAC_ESP_PDMA_LOOP("%4@,%0@+");

 			esp_count -= addr - start_addr;
 		} else {
 			unsigned int n;

 			MAC_ESP_PDMA_LOOP("%0@+,%4@");

 			if (mac_esp_wait_for_empty_fifo(esp))
 				break;

 			n = (esp_read8(ESP_TCMED) << 8) + esp_read8(ESP_TCLOW);
 			addr = start_addr + esp_count - n;
 			esp_count = n;
 		}
 	} while (esp_count);
 }

 static int mac_esp_irq_pending(struct esp *esp)
 {
 	if (esp_read8(ESP_STATUS) & ESP_STAT_INTR)
 		return 1;
 	return 0;
 }

 static u32 mac_esp_dma_length_limit(struct esp *esp, u32 dma_addr, u32 dma_len)
 {
 	return dma_len > 0xFFFF ? 0xFFFF : dma_len;
 }

 static irqreturn_t mac_scsi_esp_intr(int irq, void *dev_id)
 {
 	int got_intr;

 	/*
 	 * This is an edge triggered IRQ, so we have to be careful to
 	 * avoid missing a transition when it is shared by two ESP devices.
 	 */

 	do {
 		got_intr = 0;
 		if (esp_chips[0] &&
 		    (mac_esp_read8(esp_chips[0], ESP_STATUS) & ESP_STAT_INTR)) {
 			(void)scsi_esp_intr(irq, esp_chips[0]);
 			got_intr = 1;
 		}
 		if (esp_chips[1] &&
 		    (mac_esp_read8(esp_chips[1], ESP_STATUS) & ESP_STAT_INTR)) {
 			(void)scsi_esp_intr(irq, esp_chips[1]);
 			got_intr = 1;
 		}
 	} while (got_intr);

 	return IRQ_HANDLED;
 }

 static struct esp_driver_ops mac_esp_ops = {
 	.esp_write8       = mac_esp_write8,
 	.esp_read8        = mac_esp_read8,
 	.irq_pending      = mac_esp_irq_pending,
 	.dma_length_limit = mac_esp_dma_length_limit,
 	.reset_dma        = mac_esp_reset_dma,
 	.dma_drain        = mac_esp_dma_drain,
 	.dma_invalidate   = mac_esp_dma_invalidate,
 	.send_dma_cmd     = mac_esp_send_pdma_cmd,
 	.dma_error        = mac_esp_dma_error,
 };

 static int esp_mac_probe(struct platform_device *dev)
 {
 	struct scsi_host_template *tpnt = &scsi_esp_template;
 	struct Scsi_Host *host;
 	struct esp *esp;
 	int err;
 	struct mac_esp_priv *mep;

 	if (!MACH_IS_MAC)
 		return -ENODEV;

 	if (dev->id > 1)
 		return -ENODEV;

 	host = scsi_host_alloc(tpnt, sizeof(struct esp));

 	err = -ENOMEM;
 	if (!host)
 		goto fail;

 	host->max_id = 8;
 	host->dma_boundary = PAGE_SIZE - 1;
 	esp = shost_priv(host);

 	esp->host = host;
 	esp->dev = &dev->dev;

 	esp->command_block = kzalloc(16, GFP_KERNEL);
 	if (!esp->command_block)
 		goto fail_unlink;
 	esp->command_block_dma = (dma_addr_t)esp->command_block;

 	esp->scsi_id = 7;
 	host->this_id = esp->scsi_id;
 	esp->scsi_id_mask = 1 << esp->scsi_id;

 	mep = kzalloc(sizeof(struct mac_esp_priv), GFP_KERNEL);
 	if (!mep)
 		goto fail_free_command_block;
 	mep->esp = esp;
 	platform_set_drvdata(dev, mep);

 	switch (macintosh_config->scsi_type) {
 	case MAC_SCSI_QUADRA:
 		esp->cfreq     = 16500000;
 		esp->regs      = (void __iomem *)MAC_ESP_REGS_QUADRA;
 		mep->pdma_io   = esp->regs + MAC_ESP_PDMA_IO_OFFSET;
 		mep->pdma_regs = NULL;
 		break;
 	case MAC_SCSI_QUADRA2:
 		esp->cfreq     = 25000000;
 		esp->regs      = (void __iomem *)(MAC_ESP_REGS_QUADRA2 +
 				 dev->id * MAC_ESP_REGS_SPACING);
 		mep->pdma_io   = esp->regs + MAC_ESP_PDMA_IO_OFFSET;
 		mep->pdma_regs = (void __iomem *)(MAC_ESP_PDMA_REG +
 				 dev->id * MAC_ESP_PDMA_REG_SPACING);
 		nubus_writel(0x1d1, mep->pdma_regs);
 		break;
 	case MAC_SCSI_QUADRA3:
 		/* These quadras have a real DMA controller (the PSC) but we
 		 * don't know how to drive it so we must use PIO instead.
 		 */
 		esp->cfreq     = 25000000;
 		esp->regs      = (void __iomem *)MAC_ESP_REGS_QUADRA3;
 		mep->pdma_io   = NULL;
 		mep->pdma_regs = NULL;
 		break;
 	}
 	esp->fifo_reg = esp->regs + ESP_FDATA * 16;

 	esp->ops = &mac_esp_ops;
 	esp->flags = ESP_FLAG_NO_DMA_MAP;
 	if (mep->pdma_io == NULL) {
 		printk(KERN_INFO PFX "using PIO for controller %d\n", dev->id);
 		esp_write8(0, ESP_TCLOW);
 		esp_write8(0, ESP_TCMED);
 		esp->flags |= ESP_FLAG_DISABLE_SYNC;
 		mac_esp_ops.send_dma_cmd = esp_send_pio_cmd;
 	} else {
 		printk(KERN_INFO PFX "using PDMA for controller %d\n", dev->id);
 	}

 	host->irq = IRQ_MAC_SCSI;

 	/* The request_irq() call is intended to succeed for the first device
 	 * and fail for the second device.
 	 */
 	err = request_irq(host->irq, mac_scsi_esp_intr, 0, "ESP", NULL);
 	spin_lock(&esp_chips_lock);
 	if (err < 0 && esp_chips[!dev->id] == NULL) {
 		spin_unlock(&esp_chips_lock);
 		goto fail_free_priv;
 	}
 	esp_chips[dev->id] = esp;
 	spin_unlock(&esp_chips_lock);

 	err = scsi_esp_register(esp);
 	if (err)
 		goto fail_free_irq;

 	return 0;

 fail_free_irq:
 	spin_lock(&esp_chips_lock);
 	esp_chips[dev->id] = NULL;
 	if (esp_chips[!dev->id] == NULL) {
 		spin_unlock(&esp_chips_lock);
 		free_irq(host->irq, NULL);
 	} else
 		spin_unlock(&esp_chips_lock);
 fail_free_priv:
 	kfree(mep);
 fail_free_command_block:
 	kfree(esp->command_block);
 fail_unlink:
 	scsi_host_put(host);
 fail:
 	return err;
 }

 static int esp_mac_remove(struct platform_device *dev)
 {
 	struct mac_esp_priv *mep = platform_get_drvdata(dev);
 	struct esp *esp = mep->esp;
 	unsigned int irq = esp->host->irq;

 	scsi_esp_unregister(esp);

 	spin_lock(&esp_chips_lock);
 	esp_chips[dev->id] = NULL;
 	if (esp_chips[!dev->id] == NULL) {
 		spin_unlock(&esp_chips_lock);
 		free_irq(irq, NULL);
 	} else
 		spin_unlock(&esp_chips_lock);

 	kfree(mep);

 	kfree(esp->command_block);

 	scsi_host_put(esp->host);

 	return 0;
 }

 static struct platform_driver esp_mac_driver = {
 	.probe    = esp_mac_probe,
 	.remove   = esp_mac_remove,
 	.driver   = {
 		.name	= DRV_MODULE_NAME,
 	},
 };

 static int __init mac_esp_init(void)
 {
 	return platform_driver_register(&esp_mac_driver);
 }

 static void __exit mac_esp_exit(void)
 {
 	platform_driver_unregister(&esp_mac_driver);
 }

 MODULE_DESCRIPTION("Mac ESP SCSI driver");
 MODULE_AUTHOR("Finn Thain");
 MODULE_LICENSE("GPL v2");
 MODULE_VERSION(DRV_VERSION);
 MODULE_ALIAS("platform:" DRV_MODULE_NAME);

 module_init(mac_esp_init);
 module_exit(mac_esp_exit);
	// SPDX-License-Identifier: GPL-2.0-only
	/* mac_esp.c: ESP front-end for Macintosh Quadra systems.
	*
	* Adapted from jazz_esp.c and the old mac_esp.c.
	*
	* The pseudo DMA algorithm is based on the one used in NetBSD.
	* See sys/arch/mac68k/obio/esp.c for some background information.
	*
	* Copyright (C) 2007-2008 Finn Thain
	*/

	#include <linux/kernel.h>
	#include <linux/types.h>
	#include <linux/module.h>
	#include <linux/init.h>
	#include <linux/interrupt.h>
	#include <linux/platform_device.h>
	#include <linux/dma-mapping.h>
	#include <linux/scatterlist.h>
	#include <linux/delay.h>
	#include <linux/io.h>
	#include <linux/nubus.h>
	#include <linux/slab.h>

	#include <asm/irq.h>
	#include <asm/dma.h>
	#include <asm/macints.h>
	#include <asm/macintosh.h>
	#include <asm/mac_via.h>

	#include <scsi/scsi_host.h>

	#include "esp_scsi.h"

	#define DRV_MODULE_NAME "mac_esp"
	#define PFX DRV_MODULE_NAME ": "
	#define DRV_VERSION "1.000"
	#define DRV_MODULE_RELDATE "Sept 15, 2007"

	#define MAC_ESP_IO_BASE 0x50F00000
	#define MAC_ESP_REGS_QUADRA (MAC_ESP_IO_BASE + 0x10000)
	#define MAC_ESP_REGS_QUADRA2 (MAC_ESP_IO_BASE + 0xF000)
	#define MAC_ESP_REGS_QUADRA3 (MAC_ESP_IO_BASE + 0x18000)
	#define MAC_ESP_REGS_SPACING 0x402
	#define MAC_ESP_PDMA_REG 0xF9800024
	#define MAC_ESP_PDMA_REG_SPACING 0x4
	#define MAC_ESP_PDMA_IO_OFFSET 0x100

	#define esp_read8(REG) mac_esp_read8(esp, REG)
	#define esp_write8(VAL, REG) mac_esp_write8(esp, VAL, REG)

	struct mac_esp_priv {
	struct esp *esp;
	void __iomem *pdma_regs;
	void __iomem *pdma_io;
	};
	static struct esp *esp_chips[2];
	static DEFINE_SPINLOCK(esp_chips_lock);

	#define MAC_ESP_GET_PRIV(esp) ((struct mac_esp_priv *) \
	dev_get_drvdata((esp)->dev))

	static inline void mac_esp_write8(struct esp *esp, u8 val, unsigned long reg)
	{
	nubus_writeb(val, esp->regs + reg * 16);
	}

	static inline u8 mac_esp_read8(struct esp *esp, unsigned long reg)
	{
	return nubus_readb(esp->regs + reg * 16);
	}

	static void mac_esp_reset_dma(struct esp *esp)
	{
	/* Nothing to do. */
	}

	static void mac_esp_dma_drain(struct esp *esp)
	{
	/* Nothing to do. */
	}

	static void mac_esp_dma_invalidate(struct esp *esp)
	{
	/* Nothing to do. */
	}

	static int mac_esp_dma_error(struct esp *esp)
	{
	return esp->send_cmd_error;
	}

	static inline int mac_esp_wait_for_empty_fifo(struct esp *esp)
	{
	int i = 500000;

	do {
	if (!(esp_read8(ESP_FFLAGS) & ESP_FF_FBYTES))
	return 0;

	if (esp_read8(ESP_STATUS) & ESP_STAT_INTR)
	return 1;

	udelay(2);
	} while (--i);

	printk(KERN_ERR PFX "FIFO is not empty (sreg %02x)\n",
	esp_read8(ESP_STATUS));
	esp->send_cmd_error = 1;
	return 1;
	}

	static inline int mac_esp_wait_for_dreq(struct esp *esp)
	{
	struct mac_esp_priv *mep = MAC_ESP_GET_PRIV(esp);
	int i = 500000;

	do {
	if (mep->pdma_regs == NULL) {
	if (via2_scsi_drq_pending())
	return 0;
	} else {
	if (nubus_readl(mep->pdma_regs) & 0x200)
	return 0;
	}

	if (esp_read8(ESP_STATUS) & ESP_STAT_INTR)
	return 1;

	udelay(2);
	} while (--i);

	printk(KERN_ERR PFX "PDMA timeout (sreg %02x)\n",
	esp_read8(ESP_STATUS));
	esp->send_cmd_error = 1;
	return 1;
	}

	#define MAC_ESP_PDMA_LOOP(operands) \
	asm volatile ( \
	" tstw %1 \n" \
	" jbeq 20f \n" \
	"1: movew " operands " \n" \
	"2: movew " operands " \n" \
	"3: movew " operands " \n" \
	"4: movew " operands " \n" \
	"5: movew " operands " \n" \
	"6: movew " operands " \n" \
	"7: movew " operands " \n" \
	"8: movew " operands " \n" \
	"9: movew " operands " \n" \
	"10: movew " operands " \n" \
	"11: movew " operands " \n" \
	"12: movew " operands " \n" \
	"13: movew " operands " \n" \
	"14: movew " operands " \n" \
	"15: movew " operands " \n" \
	"16: movew " operands " \n" \
	" subqw #1,%1 \n" \
	" jbne 1b \n" \
	"20: tstw %2 \n" \
	" jbeq 30f \n" \
	"21: movew " operands " \n" \
	" subqw #1,%2 \n" \
	" jbne 21b \n" \
	"30: tstw %3 \n" \
	" jbeq 40f \n" \
	"31: moveb " operands " \n" \
	"32: nop \n" \
	"40: \n" \
	" \n" \
	" .section __ex_table,\"a\" \n" \
	" .align 4 \n" \
	" .long 1b,40b \n" \
	" .long 2b,40b \n" \
	" .long 3b,40b \n" \
	" .long 4b,40b \n" \
	" .long 5b,40b \n" \
	" .long 6b,40b \n" \
	" .long 7b,40b \n" \
	" .long 8b,40b \n" \
	" .long 9b,40b \n" \
	" .long 10b,40b \n" \
	" .long 11b,40b \n" \
	" .long 12b,40b \n" \
	" .long 13b,40b \n" \
	" .long 14b,40b \n" \
	" .long 15b,40b \n" \
	" .long 16b,40b \n" \
	" .long 21b,40b \n" \
	" .long 31b,40b \n" \
	" .long 32b,40b \n" \
	" .previous \n" \
	: "+a" (addr), "+r" (count32), "+r" (count2) \
	: "g" (count1), "a" (mep->pdma_io))

	static void mac_esp_send_pdma_cmd(struct esp *esp, u32 addr, u32 esp_count,
	u32 dma_count, int write, u8 cmd)
	{
	struct mac_esp_priv *mep = MAC_ESP_GET_PRIV(esp);

	esp->send_cmd_error = 0;

	if (!write)
	scsi_esp_cmd(esp, ESP_CMD_FLUSH);

	esp_write8((esp_count >> 0) & 0xFF, ESP_TCLOW);
	esp_write8((esp_count >> 8) & 0xFF, ESP_TCMED);

	scsi_esp_cmd(esp, cmd);

	do {
	unsigned int count32 = esp_count >> 5;
	unsigned int count2 = (esp_count & 0x1F) >> 1;
	unsigned int count1 = esp_count & 1;
	unsigned int start_addr = addr;

	if (mac_esp_wait_for_dreq(esp))
	break;

	if (write) {
	MAC_ESP_PDMA_LOOP("%4@,%0@+");

	esp_count -= addr - start_addr;
	} else {
	unsigned int n;

	MAC_ESP_PDMA_LOOP("%0@+,%4@");

	if (mac_esp_wait_for_empty_fifo(esp))
	break;

	n = (esp_read8(ESP_TCMED) << 8) + esp_read8(ESP_TCLOW);
	addr = start_addr + esp_count - n;
	esp_count = n;
	}
	} while (esp_count);
	}

	static int mac_esp_irq_pending(struct esp *esp)
	{
	if (esp_read8(ESP_STATUS) & ESP_STAT_INTR)
	return 1;
	return 0;
	}

	static u32 mac_esp_dma_length_limit(struct esp *esp, u32 dma_addr, u32 dma_len)
	{
	return dma_len > 0xFFFF ? 0xFFFF : dma_len;
	}

	static irqreturn_t mac_scsi_esp_intr(int irq, void *dev_id)
	{
	int got_intr;

	/*
	* This is an edge triggered IRQ, so we have to be careful to
	* avoid missing a transition when it is shared by two ESP devices.
	*/

	do {
	got_intr = 0;
	if (esp_chips[0] &&
	(mac_esp_read8(esp_chips[0], ESP_STATUS) & ESP_STAT_INTR)) {
	(void)scsi_esp_intr(irq, esp_chips[0]);
	got_intr = 1;
	}
	if (esp_chips[1] &&
	(mac_esp_read8(esp_chips[1], ESP_STATUS) & ESP_STAT_INTR)) {
	(void)scsi_esp_intr(irq, esp_chips[1]);
	got_intr = 1;
	}
	} while (got_intr);

	return IRQ_HANDLED;
	}

	static struct esp_driver_ops mac_esp_ops = {
	.esp_write8 = mac_esp_write8,
	.esp_read8 = mac_esp_read8,
	.irq_pending = mac_esp_irq_pending,
	.dma_length_limit = mac_esp_dma_length_limit,
	.reset_dma = mac_esp_reset_dma,
	.dma_drain = mac_esp_dma_drain,
	.dma_invalidate = mac_esp_dma_invalidate,
	.send_dma_cmd = mac_esp_send_pdma_cmd,
	.dma_error = mac_esp_dma_error,
	};

	static int esp_mac_probe(struct platform_device *dev)
	{
	struct scsi_host_template *tpnt = &scsi_esp_template;
	struct Scsi_Host *host;
	struct esp *esp;
	int err;
	struct mac_esp_priv *mep;

	if (!MACH_IS_MAC)
	return -ENODEV;

	if (dev->id > 1)
	return -ENODEV;

	host = scsi_host_alloc(tpnt, sizeof(struct esp));

	err = -ENOMEM;
	if (!host)
	goto fail;

	host->max_id = 8;
	host->dma_boundary = PAGE_SIZE - 1;
	esp = shost_priv(host);

	esp->host = host;
	esp->dev = &dev->dev;

	esp->command_block = kzalloc(16, GFP_KERNEL);
	if (!esp->command_block)
	goto fail_unlink;
	esp->command_block_dma = (dma_addr_t)esp->command_block;

	esp->scsi_id = 7;
	host->this_id = esp->scsi_id;
	esp->scsi_id_mask = 1 << esp->scsi_id;

	mep = kzalloc(sizeof(struct mac_esp_priv), GFP_KERNEL);
	if (!mep)
	goto fail_free_command_block;
	mep->esp = esp;
	platform_set_drvdata(dev, mep);

	switch (macintosh_config->scsi_type) {
	case MAC_SCSI_QUADRA:
	esp->cfreq = 16500000;
	esp->regs = (void __iomem *)MAC_ESP_REGS_QUADRA;
	mep->pdma_io = esp->regs + MAC_ESP_PDMA_IO_OFFSET;
	mep->pdma_regs = NULL;
	break;
	case MAC_SCSI_QUADRA2:
	esp->cfreq = 25000000;
	esp->regs = (void __iomem *)(MAC_ESP_REGS_QUADRA2 +
	dev->id * MAC_ESP_REGS_SPACING);
	mep->pdma_io = esp->regs + MAC_ESP_PDMA_IO_OFFSET;
	mep->pdma_regs = (void __iomem *)(MAC_ESP_PDMA_REG +
	dev->id * MAC_ESP_PDMA_REG_SPACING);
	nubus_writel(0x1d1, mep->pdma_regs);
	break;
	case MAC_SCSI_QUADRA3:
	/* These quadras have a real DMA controller (the PSC) but we
	* don't know how to drive it so we must use PIO instead.
	*/
	esp->cfreq = 25000000;
	esp->regs = (void __iomem *)MAC_ESP_REGS_QUADRA3;
	mep->pdma_io = NULL;
	mep->pdma_regs = NULL;
	break;
	}
	esp->fifo_reg = esp->regs + ESP_FDATA * 16;

	esp->ops = &mac_esp_ops;
	esp->flags = ESP_FLAG_NO_DMA_MAP;
	if (mep->pdma_io == NULL) {
	printk(KERN_INFO PFX "using PIO for controller %d\n", dev->id);
	esp_write8(0, ESP_TCLOW);
	esp_write8(0, ESP_TCMED);
	esp->flags \|= ESP_FLAG_DISABLE_SYNC;
	mac_esp_ops.send_dma_cmd = esp_send_pio_cmd;
	} else {
	printk(KERN_INFO PFX "using PDMA for controller %d\n", dev->id);
	}

	host->irq = IRQ_MAC_SCSI;

	/* The request_irq() call is intended to succeed for the first device
	* and fail for the second device.
	*/
	err = request_irq(host->irq, mac_scsi_esp_intr, 0, "ESP", NULL);
	spin_lock(&esp_chips_lock);
	if (err < 0 && esp_chips[!dev->id] == NULL) {
	spin_unlock(&esp_chips_lock);
	goto fail_free_priv;
	}
	esp_chips[dev->id] = esp;
	spin_unlock(&esp_chips_lock);

	err = scsi_esp_register(esp);
	if (err)
	goto fail_free_irq;

	return 0;

	fail_free_irq:
	spin_lock(&esp_chips_lock);
	esp_chips[dev->id] = NULL;
	if (esp_chips[!dev->id] == NULL) {
	spin_unlock(&esp_chips_lock);
	free_irq(host->irq, NULL);
	} else
	spin_unlock(&esp_chips_lock);
	fail_free_priv:
	kfree(mep);
	fail_free_command_block:
	kfree(esp->command_block);
	fail_unlink:
	scsi_host_put(host);
	fail:
	return err;
	}

	static int esp_mac_remove(struct platform_device *dev)
	{
	struct mac_esp_priv *mep = platform_get_drvdata(dev);
	struct esp *esp = mep->esp;
	unsigned int irq = esp->host->irq;

	scsi_esp_unregister(esp);

	spin_lock(&esp_chips_lock);
	esp_chips[dev->id] = NULL;
	if (esp_chips[!dev->id] == NULL) {
	spin_unlock(&esp_chips_lock);
	free_irq(irq, NULL);
	} else
	spin_unlock(&esp_chips_lock);

	kfree(mep);

	kfree(esp->command_block);

	scsi_host_put(esp->host);

	return 0;
	}

	static struct platform_driver esp_mac_driver = {
	.probe = esp_mac_probe,
	.remove = esp_mac_remove,
	.driver = {
	.name = DRV_MODULE_NAME,
	},
	};

	static int __init mac_esp_init(void)
	{
	return platform_driver_register(&esp_mac_driver);
	}

	static void __exit mac_esp_exit(void)
	{
	platform_driver_unregister(&esp_mac_driver);
	}

	MODULE_DESCRIPTION("Mac ESP SCSI driver");
	MODULE_AUTHOR("Finn Thain");
	MODULE_LICENSE("GPL v2");
	MODULE_VERSION(DRV_VERSION);
	MODULE_ALIAS("platform:" DRV_MODULE_NAME);

	module_init(mac_esp_init);
	module_exit(mac_esp_exit);