drivers/sbus/char/bbc_i2c.c - linux/kernel/git/davem/net-next - Git at Google

 /* $Id: bbc_i2c.c,v 1.2 2001/04/02 09:59:08 davem Exp $
  * bbc_i2c.c: I2C low-level driver for BBC device on UltraSPARC-III
  *            platforms.
  *
  * Copyright (C) 2001 David S. Miller (davem@redhat.com)
  */

 #include <linux/module.h>
 #include <linux/kernel.h>
 #include <linux/types.h>
 #include <linux/slab.h>
 #include <linux/sched.h>
 #include <linux/wait.h>
 #include <linux/delay.h>
 #include <linux/init.h>
 #include <linux/interrupt.h>
 #include <asm/oplib.h>
 #include <asm/ebus.h>
 #include <asm/spitfire.h>
 #include <asm/bbc.h>

 #include "bbc_i2c.h"

 /* Convert this driver to use i2c bus layer someday... */
 #define I2C_PCF_PIN	0x80
 #define I2C_PCF_ESO	0x40
 #define I2C_PCF_ES1	0x20
 #define I2C_PCF_ES2	0x10
 #define I2C_PCF_ENI	0x08
 #define I2C_PCF_STA	0x04
 #define I2C_PCF_STO	0x02
 #define I2C_PCF_ACK	0x01

 #define I2C_PCF_START    (I2C_PCF_PIN | I2C_PCF_ESO | I2C_PCF_ENI | I2C_PCF_STA | I2C_PCF_ACK)
 #define I2C_PCF_STOP     (I2C_PCF_PIN | I2C_PCF_ESO | I2C_PCF_STO | I2C_PCF_ACK)
 #define I2C_PCF_REPSTART (              I2C_PCF_ESO | I2C_PCF_STA | I2C_PCF_ACK)
 #define I2C_PCF_IDLE     (I2C_PCF_PIN | I2C_PCF_ESO               | I2C_PCF_ACK)

 #define I2C_PCF_INI 0x40   /* 1 if not initialized */
 #define I2C_PCF_STS 0x20
 #define I2C_PCF_BER 0x10
 #define I2C_PCF_AD0 0x08
 #define I2C_PCF_LRB 0x08
 #define I2C_PCF_AAS 0x04
 #define I2C_PCF_LAB 0x02
 #define I2C_PCF_BB  0x01

 /* The BBC devices have two I2C controllers.  The first I2C controller
  * connects mainly to configuration proms (NVRAM, cpu configuration,
  * dimm types, etc.).  Whereas the second I2C controller connects to
  * environmental control devices such as fans and temperature sensors.
  * The second controller also connects to the smartcard reader, if present.
  */

 #define NUM_CHILDREN	8
 struct bbc_i2c_bus {
 	struct bbc_i2c_bus		*next;
 	int				index;
 	spinlock_t			lock;
 	void				__iomem *i2c_bussel_reg;
 	void				__iomem *i2c_control_regs;
 	unsigned char			own, clock;

 	wait_queue_head_t		wq;
 	volatile int			waiting;

 	struct linux_ebus_device	*bus_edev;
 	struct {
 		struct linux_ebus_child	*device;
 		int			client_claimed;
 	} devs[NUM_CHILDREN];
 };

 static struct bbc_i2c_bus *all_bbc_i2c;

 struct bbc_i2c_client {
 	struct bbc_i2c_bus	*bp;
 	struct linux_ebus_child	*echild;
 	int			bus;
 	int			address;
 };

 static int find_device(struct bbc_i2c_bus *bp, struct linux_ebus_child *echild)
 {
 	int i;

 	for (i = 0; i < NUM_CHILDREN; i++) {
 		if (bp->devs[i].device == echild) {
 			if (bp->devs[i].client_claimed)
 				return 0;
 			return 1;
 		}
 	}
 	return 0;
 }

 static void set_device_claimage(struct bbc_i2c_bus *bp, struct linux_ebus_child *echild, int val)
 {
 	int i;

 	for (i = 0; i < NUM_CHILDREN; i++) {
 		if (bp->devs[i].device == echild) {
 			bp->devs[i].client_claimed = val;
 			return;
 		}
 	}
 }

 #define claim_device(BP,ECHILD)		set_device_claimage(BP,ECHILD,1)
 #define release_device(BP,ECHILD)	set_device_claimage(BP,ECHILD,0)

 static struct bbc_i2c_bus *find_bus_for_device(struct linux_ebus_child *echild)
 {
 	struct bbc_i2c_bus *bp = all_bbc_i2c;

 	while (bp != NULL) {
 		if (find_device(bp, echild) != 0)
 			break;
 		bp = bp->next;
 	}

 	return bp;
 }

 struct linux_ebus_child *bbc_i2c_getdev(int index)
 {
 	struct bbc_i2c_bus *bp = all_bbc_i2c;
 	struct linux_ebus_child *echild = NULL;
 	int curidx = 0;

 	while (bp != NULL) {
 		struct bbc_i2c_bus *next = bp->next;
 		int i;

 		for (i = 0; i < NUM_CHILDREN; i++) {
 			if (!(echild = bp->devs[i].device))
 				break;
 			if (curidx == index)
 				goto out;
 			echild = NULL;
 			curidx++;
 		}
 		bp = next;
 	}
 out:
 	if (curidx == index)
 		return echild;
 	return NULL;
 }

 struct bbc_i2c_client *bbc_i2c_attach(struct linux_ebus_child *echild)
 {
 	struct bbc_i2c_bus *bp = find_bus_for_device(echild);
 	struct bbc_i2c_client *client;

 	if (!bp)
 		return NULL;
 	client = kmalloc(sizeof(*client), GFP_KERNEL);
 	if (!client)
 		return NULL;
 	memset(client, 0, sizeof(*client));
 	client->bp = bp;
 	client->echild = echild;
 	client->bus = echild->resource[0].start;
 	client->address = echild->resource[1].start;

 	claim_device(bp, echild);

 	return client;
 }

 void bbc_i2c_detach(struct bbc_i2c_client *client)
 {
 	struct bbc_i2c_bus *bp = client->bp;
 	struct linux_ebus_child *echild = client->echild;

 	release_device(bp, echild);
 	kfree(client);
 }

 static int wait_for_pin(struct bbc_i2c_bus *bp, u8 *status)
 {
 	DECLARE_WAITQUEUE(wait, current);
 	int limit = 32;
 	int ret = 1;

 	bp->waiting = 1;
 	add_wait_queue(&bp->wq, &wait);
 	while (limit-- > 0) {
 		unsigned long val;

 		val = wait_event_interruptible_timeout(
 				bp->wq,
 				(((*status = readb(bp->i2c_control_regs + 0))
 				  & I2C_PCF_PIN) == 0),
 				msecs_to_jiffies(250));
 		if (val > 0) {
 			ret = 0;
 			break;
 		}
 	}
 	remove_wait_queue(&bp->wq, &wait);
 	bp->waiting = 0;

 	return ret;
 }

 int bbc_i2c_writeb(struct bbc_i2c_client *client, unsigned char val, int off)
 {
 	struct bbc_i2c_bus *bp = client->bp;
 	int address = client->address;
 	u8 status;
 	int ret = -1;

 	if (bp->i2c_bussel_reg != NULL)
 		writeb(client->bus, bp->i2c_bussel_reg);

 	writeb(address, bp->i2c_control_regs + 0x1);
 	writeb(I2C_PCF_START, bp->i2c_control_regs + 0x0);
 	if (wait_for_pin(bp, &status))
 		goto out;

 	writeb(off, bp->i2c_control_regs + 0x1);
 	if (wait_for_pin(bp, &status) ||
 	    (status & I2C_PCF_LRB) != 0)
 		goto out;

 	writeb(val, bp->i2c_control_regs + 0x1);
 	if (wait_for_pin(bp, &status))
 		goto out;

 	ret = 0;

 out:
 	writeb(I2C_PCF_STOP, bp->i2c_control_regs + 0x0);
 	return ret;
 }

 int bbc_i2c_readb(struct bbc_i2c_client *client, unsigned char *byte, int off)
 {
 	struct bbc_i2c_bus *bp = client->bp;
 	unsigned char address = client->address, status;
 	int ret = -1;

 	if (bp->i2c_bussel_reg != NULL)
 		writeb(client->bus, bp->i2c_bussel_reg);

 	writeb(address, bp->i2c_control_regs + 0x1);
 	writeb(I2C_PCF_START, bp->i2c_control_regs + 0x0);
 	if (wait_for_pin(bp, &status))
 		goto out;

 	writeb(off, bp->i2c_control_regs + 0x1);
 	if (wait_for_pin(bp, &status) ||
 	    (status & I2C_PCF_LRB) != 0)
 		goto out;

 	writeb(I2C_PCF_STOP, bp->i2c_control_regs + 0x0);

 	address |= 0x1; /* READ */

 	writeb(address, bp->i2c_control_regs + 0x1);
 	writeb(I2C_PCF_START, bp->i2c_control_regs + 0x0);
 	if (wait_for_pin(bp, &status))
 		goto out;

 	/* Set PIN back to one so the device sends the first
 	 * byte.
 	 */
 	(void) readb(bp->i2c_control_regs + 0x1);
 	if (wait_for_pin(bp, &status))
 		goto out;

 	writeb(I2C_PCF_ESO | I2C_PCF_ENI, bp->i2c_control_regs + 0x0);
 	*byte = readb(bp->i2c_control_regs + 0x1);
 	if (wait_for_pin(bp, &status))
 		goto out;

 	ret = 0;

 out:
 	writeb(I2C_PCF_STOP, bp->i2c_control_regs + 0x0);
 	(void) readb(bp->i2c_control_regs + 0x1);

 	return ret;
 }

 int bbc_i2c_write_buf(struct bbc_i2c_client *client,
 		      char *buf, int len, int off)
 {
 	int ret = 0;

 	while (len > 0) {
 		int err = bbc_i2c_writeb(client, *buf, off);

 		if (err < 0) {
 			ret = err;
 			break;
 		}

 		len--;
 		buf++;
 		off++;
 	}
 	return ret;
 }

 int bbc_i2c_read_buf(struct bbc_i2c_client *client,
 		     char *buf, int len, int off)
 {
 	int ret = 0;

 	while (len > 0) {
 		int err = bbc_i2c_readb(client, buf, off);
 		if (err < 0) {
 			ret = err;
 			break;
 		}
 		len--;
 		buf++;
 		off++;
 	}

 	return ret;
 }

 EXPORT_SYMBOL(bbc_i2c_getdev);
 EXPORT_SYMBOL(bbc_i2c_attach);
 EXPORT_SYMBOL(bbc_i2c_detach);
 EXPORT_SYMBOL(bbc_i2c_writeb);
 EXPORT_SYMBOL(bbc_i2c_readb);
 EXPORT_SYMBOL(bbc_i2c_write_buf);
 EXPORT_SYMBOL(bbc_i2c_read_buf);

 static irqreturn_t bbc_i2c_interrupt(int irq, void *dev_id)
 {
 	struct bbc_i2c_bus *bp = dev_id;

 	/* PIN going from set to clear is the only event which
 	 * makes the i2c assert an interrupt.
 	 */
 	if (bp->waiting &&
 	    !(readb(bp->i2c_control_regs + 0x0) & I2C_PCF_PIN))
 		wake_up_interruptible(&bp->wq);

 	return IRQ_HANDLED;
 }

 static void __init reset_one_i2c(struct bbc_i2c_bus *bp)
 {
 	writeb(I2C_PCF_PIN, bp->i2c_control_regs + 0x0);
 	writeb(bp->own, bp->i2c_control_regs + 0x1);
 	writeb(I2C_PCF_PIN | I2C_PCF_ES1, bp->i2c_control_regs + 0x0);
 	writeb(bp->clock, bp->i2c_control_regs + 0x1);
 	writeb(I2C_PCF_IDLE, bp->i2c_control_regs + 0x0);
 }

 static int __init attach_one_i2c(struct linux_ebus_device *edev, int index)
 {
 	struct bbc_i2c_bus *bp = kmalloc(sizeof(*bp), GFP_KERNEL);
 	struct linux_ebus_child *echild;
 	int entry;

 	if (!bp)
 		return -ENOMEM;
 	memset(bp, 0, sizeof(*bp));

 	bp->i2c_control_regs = ioremap(edev->resource[0].start, 0x2);
 	if (!bp->i2c_control_regs)
 		goto fail;

 	if (edev->num_addrs == 2) {
 		bp->i2c_bussel_reg = ioremap(edev->resource[1].start, 0x1);
 		if (!bp->i2c_bussel_reg)
 			goto fail;
 	}

 	bp->waiting = 0;
 	init_waitqueue_head(&bp->wq);
 	if (request_irq(edev->irqs[0], bbc_i2c_interrupt,
 			IRQF_SHARED, "bbc_i2c", bp))
 		goto fail;

 	bp->index = index;
 	bp->bus_edev = edev;

 	spin_lock_init(&bp->lock);
 	bp->next = all_bbc_i2c;
 	all_bbc_i2c = bp;

 	entry = 0;
 	for (echild = edev->children;
 	     echild && entry < 8;
 	     echild = echild->next, entry++) {
 		bp->devs[entry].device = echild;
 		bp->devs[entry].client_claimed = 0;
 	}

 	writeb(I2C_PCF_PIN, bp->i2c_control_regs + 0x0);
 	bp->own = readb(bp->i2c_control_regs + 0x01);
 	writeb(I2C_PCF_PIN | I2C_PCF_ES1, bp->i2c_control_regs + 0x0);
 	bp->clock = readb(bp->i2c_control_regs + 0x01);

 	printk(KERN_INFO "i2c-%d: Regs at %p, %d devices, own %02x, clock %02x.\n",
 	       bp->index, bp->i2c_control_regs, entry, bp->own, bp->clock);

 	reset_one_i2c(bp);

 	return 0;

 fail:
 	if (bp->i2c_bussel_reg)
 		iounmap(bp->i2c_bussel_reg);
 	if (bp->i2c_control_regs)
 		iounmap(bp->i2c_control_regs);
 	kfree(bp);
 	return -EINVAL;
 }

 static int __init bbc_present(void)
 {
 	struct linux_ebus *ebus = NULL;
 	struct linux_ebus_device *edev = NULL;

 	for_each_ebus(ebus) {
 		for_each_ebusdev(edev, ebus) {
 			if (!strcmp(edev->prom_node->name, "bbc"))
 				return 1;
 		}
 	}
 	return 0;
 }

 extern int bbc_envctrl_init(void);
 extern void bbc_envctrl_cleanup(void);
 static void bbc_i2c_cleanup(void);

 static int __init bbc_i2c_init(void)
 {
 	struct linux_ebus *ebus = NULL;
 	struct linux_ebus_device *edev = NULL;
 	int err, index = 0;

 	if ((tlb_type != cheetah && tlb_type != cheetah_plus) ||
 	    !bbc_present())
 		return -ENODEV;

 	for_each_ebus(ebus) {
 		for_each_ebusdev(edev, ebus) {
 			if (!strcmp(edev->prom_node->name, "i2c")) {
 				if (!attach_one_i2c(edev, index))
 					index++;
 			}
 		}
 	}

 	if (!index)
 		return -ENODEV;

 	err = bbc_envctrl_init();
 	if (err)
 		bbc_i2c_cleanup();
 	return err;
 }

 static void bbc_i2c_cleanup(void)
 {
 	struct bbc_i2c_bus *bp = all_bbc_i2c;

 	bbc_envctrl_cleanup();

 	while (bp != NULL) {
 		struct bbc_i2c_bus *next = bp->next;

 		free_irq(bp->bus_edev->irqs[0], bp);

 		if (bp->i2c_bussel_reg)
 			iounmap(bp->i2c_bussel_reg);
 		if (bp->i2c_control_regs)
 			iounmap(bp->i2c_control_regs);

 		kfree(bp);

 		bp = next;
 	}
 	all_bbc_i2c = NULL;
 }

 module_init(bbc_i2c_init);
 module_exit(bbc_i2c_cleanup);
 MODULE_LICENSE("GPL");
	/* $Id: bbc_i2c.c,v 1.2 2001/04/02 09:59:08 davem Exp $
	* bbc_i2c.c: I2C low-level driver for BBC device on UltraSPARC-III
	* platforms.
	*
	* Copyright (C) 2001 David S. Miller (davem@redhat.com)
	*/

	#include <linux/module.h>
	#include <linux/kernel.h>
	#include <linux/types.h>
	#include <linux/slab.h>
	#include <linux/sched.h>
	#include <linux/wait.h>
	#include <linux/delay.h>
	#include <linux/init.h>
	#include <linux/interrupt.h>
	#include <asm/oplib.h>
	#include <asm/ebus.h>
	#include <asm/spitfire.h>
	#include <asm/bbc.h>

	#include "bbc_i2c.h"

	/* Convert this driver to use i2c bus layer someday... */
	#define I2C_PCF_PIN 0x80
	#define I2C_PCF_ESO 0x40
	#define I2C_PCF_ES1 0x20
	#define I2C_PCF_ES2 0x10
	#define I2C_PCF_ENI 0x08
	#define I2C_PCF_STA 0x04
	#define I2C_PCF_STO 0x02
	#define I2C_PCF_ACK 0x01

	#define I2C_PCF_START (I2C_PCF_PIN \| I2C_PCF_ESO \| I2C_PCF_ENI \| I2C_PCF_STA \| I2C_PCF_ACK)
	#define I2C_PCF_STOP (I2C_PCF_PIN \| I2C_PCF_ESO \| I2C_PCF_STO \| I2C_PCF_ACK)
	#define I2C_PCF_REPSTART ( I2C_PCF_ESO \| I2C_PCF_STA \| I2C_PCF_ACK)
	#define I2C_PCF_IDLE (I2C_PCF_PIN \| I2C_PCF_ESO \| I2C_PCF_ACK)

	#define I2C_PCF_INI 0x40 /* 1 if not initialized */
	#define I2C_PCF_STS 0x20
	#define I2C_PCF_BER 0x10
	#define I2C_PCF_AD0 0x08
	#define I2C_PCF_LRB 0x08
	#define I2C_PCF_AAS 0x04
	#define I2C_PCF_LAB 0x02
	#define I2C_PCF_BB 0x01

	/* The BBC devices have two I2C controllers. The first I2C controller
	* connects mainly to configuration proms (NVRAM, cpu configuration,
	* dimm types, etc.). Whereas the second I2C controller connects to
	* environmental control devices such as fans and temperature sensors.
	* The second controller also connects to the smartcard reader, if present.
	*/

	#define NUM_CHILDREN 8
	struct bbc_i2c_bus {
	struct bbc_i2c_bus *next;
	int index;
	spinlock_t lock;
	void __iomem *i2c_bussel_reg;
	void __iomem *i2c_control_regs;
	unsigned char own, clock;

	wait_queue_head_t wq;
	volatile int waiting;

	struct linux_ebus_device *bus_edev;
	struct {
	struct linux_ebus_child *device;
	int client_claimed;
	} devs[NUM_CHILDREN];
	};

	static struct bbc_i2c_bus *all_bbc_i2c;

	struct bbc_i2c_client {
	struct bbc_i2c_bus *bp;
	struct linux_ebus_child *echild;
	int bus;
	int address;
	};

	static int find_device(struct bbc_i2c_bus bp, struct linux_ebus_child echild)
	{
	int i;

	for (i = 0; i < NUM_CHILDREN; i++) {
	if (bp->devs[i].device == echild) {
	if (bp->devs[i].client_claimed)
	return 0;
	return 1;
	}
	}
	return 0;
	}

	static void set_device_claimage(struct bbc_i2c_bus bp, struct linux_ebus_child echild, int val)
	{
	int i;

	for (i = 0; i < NUM_CHILDREN; i++) {
	if (bp->devs[i].device == echild) {
	bp->devs[i].client_claimed = val;
	return;
	}
	}
	}

	#define claim_device(BP,ECHILD) set_device_claimage(BP,ECHILD,1)
	#define release_device(BP,ECHILD) set_device_claimage(BP,ECHILD,0)

	static struct bbc_i2c_bus find_bus_for_device(struct linux_ebus_child echild)
	{
	struct bbc_i2c_bus *bp = all_bbc_i2c;

	while (bp != NULL) {
	if (find_device(bp, echild) != 0)
	break;
	bp = bp->next;
	}

	return bp;
	}

	struct linux_ebus_child *bbc_i2c_getdev(int index)
	{
	struct bbc_i2c_bus *bp = all_bbc_i2c;
	struct linux_ebus_child *echild = NULL;
	int curidx = 0;

	while (bp != NULL) {
	struct bbc_i2c_bus *next = bp->next;
	int i;

	for (i = 0; i < NUM_CHILDREN; i++) {
	if (!(echild = bp->devs[i].device))
	break;
	if (curidx == index)
	goto out;
	echild = NULL;
	curidx++;
	}
	bp = next;
	}
	out:
	if (curidx == index)
	return echild;
	return NULL;
	}

	struct bbc_i2c_client bbc_i2c_attach(struct linux_ebus_child echild)
	{
	struct bbc_i2c_bus *bp = find_bus_for_device(echild);
	struct bbc_i2c_client *client;

	if (!bp)
	return NULL;
	client = kmalloc(sizeof(*client), GFP_KERNEL);
	if (!client)
	return NULL;
	memset(client, 0, sizeof(*client));
	client->bp = bp;
	client->echild = echild;
	client->bus = echild->resource[0].start;
	client->address = echild->resource[1].start;

	claim_device(bp, echild);

	return client;
	}

	void bbc_i2c_detach(struct bbc_i2c_client *client)
	{
	struct bbc_i2c_bus *bp = client->bp;
	struct linux_ebus_child *echild = client->echild;

	release_device(bp, echild);
	kfree(client);
	}

	static int wait_for_pin(struct bbc_i2c_bus bp, u8 status)
	{
	DECLARE_WAITQUEUE(wait, current);
	int limit = 32;
	int ret = 1;

	bp->waiting = 1;
	add_wait_queue(&bp->wq, &wait);
	while (limit-- > 0) {
	unsigned long val;

	val = wait_event_interruptible_timeout(
	bp->wq,
	(((*status = readb(bp->i2c_control_regs + 0))
	& I2C_PCF_PIN) == 0),
	msecs_to_jiffies(250));
	if (val > 0) {
	ret = 0;
	break;
	}
	}
	remove_wait_queue(&bp->wq, &wait);
	bp->waiting = 0;

	return ret;
	}

	int bbc_i2c_writeb(struct bbc_i2c_client *client, unsigned char val, int off)
	{
	struct bbc_i2c_bus *bp = client->bp;
	int address = client->address;
	u8 status;
	int ret = -1;

	if (bp->i2c_bussel_reg != NULL)
	writeb(client->bus, bp->i2c_bussel_reg);

	writeb(address, bp->i2c_control_regs + 0x1);
	writeb(I2C_PCF_START, bp->i2c_control_regs + 0x0);
	if (wait_for_pin(bp, &status))
	goto out;

	writeb(off, bp->i2c_control_regs + 0x1);
	if (wait_for_pin(bp, &status) \|\|
	(status & I2C_PCF_LRB) != 0)
	goto out;

	writeb(val, bp->i2c_control_regs + 0x1);
	if (wait_for_pin(bp, &status))
	goto out;

	ret = 0;

	out:
	writeb(I2C_PCF_STOP, bp->i2c_control_regs + 0x0);
	return ret;
	}

	int bbc_i2c_readb(struct bbc_i2c_client client, unsigned char byte, int off)
	{
	struct bbc_i2c_bus *bp = client->bp;
	unsigned char address = client->address, status;
	int ret = -1;

	if (bp->i2c_bussel_reg != NULL)
	writeb(client->bus, bp->i2c_bussel_reg);

	writeb(address, bp->i2c_control_regs + 0x1);
	writeb(I2C_PCF_START, bp->i2c_control_regs + 0x0);
	if (wait_for_pin(bp, &status))
	goto out;

	writeb(off, bp->i2c_control_regs + 0x1);
	if (wait_for_pin(bp, &status) \|\|
	(status & I2C_PCF_LRB) != 0)
	goto out;

	writeb(I2C_PCF_STOP, bp->i2c_control_regs + 0x0);

	address \|= 0x1; /* READ */

	writeb(address, bp->i2c_control_regs + 0x1);
	writeb(I2C_PCF_START, bp->i2c_control_regs + 0x0);
	if (wait_for_pin(bp, &status))
	goto out;

	/* Set PIN back to one so the device sends the first
	* byte.
	*/
	(void) readb(bp->i2c_control_regs + 0x1);
	if (wait_for_pin(bp, &status))
	goto out;

	writeb(I2C_PCF_ESO \| I2C_PCF_ENI, bp->i2c_control_regs + 0x0);
	*byte = readb(bp->i2c_control_regs + 0x1);
	if (wait_for_pin(bp, &status))
	goto out;

	ret = 0;

	out:
	writeb(I2C_PCF_STOP, bp->i2c_control_regs + 0x0);
	(void) readb(bp->i2c_control_regs + 0x1);

	return ret;
	}

	int bbc_i2c_write_buf(struct bbc_i2c_client *client,
	char *buf, int len, int off)
	{
	int ret = 0;

	while (len > 0) {
	int err = bbc_i2c_writeb(client, *buf, off);

	if (err < 0) {
	ret = err;
	break;
	}

	len--;
	buf++;
	off++;
	}
	return ret;
	}

	int bbc_i2c_read_buf(struct bbc_i2c_client *client,
	char *buf, int len, int off)
	{
	int ret = 0;

	while (len > 0) {
	int err = bbc_i2c_readb(client, buf, off);
	if (err < 0) {
	ret = err;
	break;
	}
	len--;
	buf++;
	off++;
	}

	return ret;
	}

	EXPORT_SYMBOL(bbc_i2c_getdev);
	EXPORT_SYMBOL(bbc_i2c_attach);
	EXPORT_SYMBOL(bbc_i2c_detach);
	EXPORT_SYMBOL(bbc_i2c_writeb);
	EXPORT_SYMBOL(bbc_i2c_readb);
	EXPORT_SYMBOL(bbc_i2c_write_buf);
	EXPORT_SYMBOL(bbc_i2c_read_buf);

	static irqreturn_t bbc_i2c_interrupt(int irq, void *dev_id)
	{
	struct bbc_i2c_bus *bp = dev_id;

	/* PIN going from set to clear is the only event which
	* makes the i2c assert an interrupt.
	*/
	if (bp->waiting &&
	!(readb(bp->i2c_control_regs + 0x0) & I2C_PCF_PIN))
	wake_up_interruptible(&bp->wq);

	return IRQ_HANDLED;
	}

	static void __init reset_one_i2c(struct bbc_i2c_bus *bp)
	{
	writeb(I2C_PCF_PIN, bp->i2c_control_regs + 0x0);
	writeb(bp->own, bp->i2c_control_regs + 0x1);
	writeb(I2C_PCF_PIN \| I2C_PCF_ES1, bp->i2c_control_regs + 0x0);
	writeb(bp->clock, bp->i2c_control_regs + 0x1);
	writeb(I2C_PCF_IDLE, bp->i2c_control_regs + 0x0);
	}

	static int __init attach_one_i2c(struct linux_ebus_device *edev, int index)
	{
	struct bbc_i2c_bus bp = kmalloc(sizeof(bp), GFP_KERNEL);
	struct linux_ebus_child *echild;
	int entry;

	if (!bp)
	return -ENOMEM;
	memset(bp, 0, sizeof(*bp));

	bp->i2c_control_regs = ioremap(edev->resource[0].start, 0x2);
	if (!bp->i2c_control_regs)
	goto fail;

	if (edev->num_addrs == 2) {
	bp->i2c_bussel_reg = ioremap(edev->resource[1].start, 0x1);
	if (!bp->i2c_bussel_reg)
	goto fail;
	}

	bp->waiting = 0;
	init_waitqueue_head(&bp->wq);
	if (request_irq(edev->irqs[0], bbc_i2c_interrupt,
	IRQF_SHARED, "bbc_i2c", bp))
	goto fail;

	bp->index = index;
	bp->bus_edev = edev;

	spin_lock_init(&bp->lock);
	bp->next = all_bbc_i2c;
	all_bbc_i2c = bp;

	entry = 0;
	for (echild = edev->children;
	echild && entry < 8;
	echild = echild->next, entry++) {
	bp->devs[entry].device = echild;
	bp->devs[entry].client_claimed = 0;
	}

	writeb(I2C_PCF_PIN, bp->i2c_control_regs + 0x0);
	bp->own = readb(bp->i2c_control_regs + 0x01);
	writeb(I2C_PCF_PIN \| I2C_PCF_ES1, bp->i2c_control_regs + 0x0);
	bp->clock = readb(bp->i2c_control_regs + 0x01);

	printk(KERN_INFO "i2c-%d: Regs at %p, %d devices, own %02x, clock %02x.\n",
	bp->index, bp->i2c_control_regs, entry, bp->own, bp->clock);

	reset_one_i2c(bp);

	return 0;

	fail:
	if (bp->i2c_bussel_reg)
	iounmap(bp->i2c_bussel_reg);
	if (bp->i2c_control_regs)
	iounmap(bp->i2c_control_regs);
	kfree(bp);
	return -EINVAL;
	}

	static int __init bbc_present(void)
	{
	struct linux_ebus *ebus = NULL;
	struct linux_ebus_device *edev = NULL;

	for_each_ebus(ebus) {
	for_each_ebusdev(edev, ebus) {
	if (!strcmp(edev->prom_node->name, "bbc"))
	return 1;
	}
	}
	return 0;
	}

	extern int bbc_envctrl_init(void);
	extern void bbc_envctrl_cleanup(void);
	static void bbc_i2c_cleanup(void);

	static int __init bbc_i2c_init(void)
	{
	struct linux_ebus *ebus = NULL;
	struct linux_ebus_device *edev = NULL;
	int err, index = 0;

	if ((tlb_type != cheetah && tlb_type != cheetah_plus) \|\|
	!bbc_present())
	return -ENODEV;

	for_each_ebus(ebus) {
	for_each_ebusdev(edev, ebus) {
	if (!strcmp(edev->prom_node->name, "i2c")) {
	if (!attach_one_i2c(edev, index))
	index++;
	}
	}
	}

	if (!index)
	return -ENODEV;

	err = bbc_envctrl_init();
	if (err)
	bbc_i2c_cleanup();
	return err;
	}

	static void bbc_i2c_cleanup(void)
	{
	struct bbc_i2c_bus *bp = all_bbc_i2c;

	bbc_envctrl_cleanup();

	while (bp != NULL) {
	struct bbc_i2c_bus *next = bp->next;

	free_irq(bp->bus_edev->irqs[0], bp);

	if (bp->i2c_bussel_reg)
	iounmap(bp->i2c_bussel_reg);
	if (bp->i2c_control_regs)
	iounmap(bp->i2c_control_regs);

	kfree(bp);

	bp = next;
	}
	all_bbc_i2c = NULL;
	}

	module_init(bbc_i2c_init);
	module_exit(bbc_i2c_cleanup);
	MODULE_LICENSE("GPL");