drivers/i2c/i2c-stub.c - arm/linux - Git at Google

 /*
     i2c-stub.c - I2C/SMBus chip emulator

     Copyright (c) 2004 Mark M. Hoffman <mhoffman@lightlink.com>
     Copyright (C) 2007-2014 Jean Delvare <jdelvare@suse.de>

     This program is free software; you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published by
     the Free Software Foundation; either version 2 of the License, or
     (at your option) any later version.

     This program is distributed in the hope that it will be useful,
     but WITHOUT ANY WARRANTY; without even the implied warranty of
     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     GNU General Public License for more details.
 */

 #define DEBUG 1
 #define pr_fmt(fmt) "i2c-stub: " fmt

 #include <linux/errno.h>
 #include <linux/i2c.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/list.h>
 #include <linux/module.h>
 #include <linux/slab.h>

 #define MAX_CHIPS 10

 /*
  * Support for I2C_FUNC_SMBUS_BLOCK_DATA is disabled by default and must
  * be enabled explicitly by setting the I2C_FUNC_SMBUS_BLOCK_DATA bits
  * in the 'functionality' module parameter.
  */
 #define STUB_FUNC_DEFAULT \
 		(I2C_FUNC_SMBUS_QUICK | I2C_FUNC_SMBUS_BYTE | \
 		 I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA | \
 		 I2C_FUNC_SMBUS_I2C_BLOCK)

 #define STUB_FUNC_ALL \
 		(STUB_FUNC_DEFAULT | I2C_FUNC_SMBUS_BLOCK_DATA)

 static unsigned short chip_addr[MAX_CHIPS];
 module_param_array(chip_addr, ushort, NULL, S_IRUGO);
 MODULE_PARM_DESC(chip_addr,
 		 "Chip addresses (up to 10, between 0x03 and 0x77)");

 static unsigned long functionality = STUB_FUNC_DEFAULT;
 module_param(functionality, ulong, S_IRUGO | S_IWUSR);
 MODULE_PARM_DESC(functionality, "Override functionality bitfield");

 /* Some chips have banked register ranges */

 static u8 bank_reg[MAX_CHIPS];
 module_param_array(bank_reg, byte, NULL, S_IRUGO);
 MODULE_PARM_DESC(bank_reg, "Bank register");

 static u8 bank_mask[MAX_CHIPS];
 module_param_array(bank_mask, byte, NULL, S_IRUGO);
 MODULE_PARM_DESC(bank_mask, "Bank value mask");

 static u8 bank_start[MAX_CHIPS];
 module_param_array(bank_start, byte, NULL, S_IRUGO);
 MODULE_PARM_DESC(bank_start, "First banked register");

 static u8 bank_end[MAX_CHIPS];
 module_param_array(bank_end, byte, NULL, S_IRUGO);
 MODULE_PARM_DESC(bank_end, "Last banked register");

 struct smbus_block_data {
 	struct list_head node;
 	u8 command;
 	u8 len;
 	u8 block[I2C_SMBUS_BLOCK_MAX];
 };

 struct stub_chip {
 	u8 pointer;
 	u16 words[256];		/* Byte operations use the LSB as per SMBus
 				   specification */
 	struct list_head smbus_blocks;

 	/* For chips with banks, extra registers are allocated dynamically */
 	u8 bank_reg;
 	u8 bank_shift;
 	u8 bank_mask;
 	u8 bank_sel;		/* Currently selected bank */
 	u8 bank_start;
 	u8 bank_end;
 	u16 bank_size;
 	u16 *bank_words;	/* Room for bank_mask * bank_size registers */
 };

 static struct stub_chip *stub_chips;
 static int stub_chips_nr;

 static struct smbus_block_data *stub_find_block(struct device *dev,
 						struct stub_chip *chip,
 						u8 command, bool create)
 {
 	struct smbus_block_data *b, *rb = NULL;

 	list_for_each_entry(b, &chip->smbus_blocks, node) {
 		if (b->command == command) {
 			rb = b;
 			break;
 		}
 	}
 	if (rb == NULL && create) {
 		rb = devm_kzalloc(dev, sizeof(*rb), GFP_KERNEL);
 		if (rb == NULL)
 			return rb;
 		rb->command = command;
 		list_add(&rb->node, &chip->smbus_blocks);
 	}
 	return rb;
 }

 static u16 *stub_get_wordp(struct stub_chip *chip, u8 offset)
 {
 	if (chip->bank_sel &&
 	    offset >= chip->bank_start && offset <= chip->bank_end)
 		return chip->bank_words +
 		       (chip->bank_sel - 1) * chip->bank_size +
 		       offset - chip->bank_start;
 	else
 		return chip->words + offset;
 }

 /* Return negative errno on error. */
 static s32 stub_xfer(struct i2c_adapter *adap, u16 addr, unsigned short flags,
 	char read_write, u8 command, int size, union i2c_smbus_data *data)
 {
 	s32 ret;
 	int i, len;
 	struct stub_chip *chip = NULL;
 	struct smbus_block_data *b;
 	u16 *wordp;

 	/* Search for the right chip */
 	for (i = 0; i < stub_chips_nr; i++) {
 		if (addr == chip_addr[i]) {
 			chip = stub_chips + i;
 			break;
 		}
 	}
 	if (!chip)
 		return -ENODEV;

 	switch (size) {

 	case I2C_SMBUS_QUICK:
 		dev_dbg(&adap->dev, "smbus quick - addr 0x%02x\n", addr);
 		ret = 0;
 		break;

 	case I2C_SMBUS_BYTE:
 		if (read_write == I2C_SMBUS_WRITE) {
 			chip->pointer = command;
 			dev_dbg(&adap->dev,
 				"smbus byte - addr 0x%02x, wrote 0x%02x.\n",
 				addr, command);
 		} else {
 			wordp = stub_get_wordp(chip, chip->pointer++);
 			data->byte = *wordp & 0xff;
 			dev_dbg(&adap->dev,
 				"smbus byte - addr 0x%02x, read  0x%02x.\n",
 				addr, data->byte);
 		}

 		ret = 0;
 		break;

 	case I2C_SMBUS_BYTE_DATA:
 		wordp = stub_get_wordp(chip, command);
 		if (read_write == I2C_SMBUS_WRITE) {
 			*wordp &= 0xff00;
 			*wordp |= data->byte;
 			dev_dbg(&adap->dev,
 				"smbus byte data - addr 0x%02x, wrote 0x%02x at 0x%02x.\n",
 				addr, data->byte, command);

 			/* Set the bank as needed */
 			if (chip->bank_words && command == chip->bank_reg) {
 				chip->bank_sel =
 					(data->byte >> chip->bank_shift)
 					& chip->bank_mask;
 				dev_dbg(&adap->dev,
 					"switching to bank %u.\n",
 					chip->bank_sel);
 			}
 		} else {
 			data->byte = *wordp & 0xff;
 			dev_dbg(&adap->dev,
 				"smbus byte data - addr 0x%02x, read  0x%02x at 0x%02x.\n",
 				addr, data->byte, command);
 		}
 		chip->pointer = command + 1;

 		ret = 0;
 		break;

 	case I2C_SMBUS_WORD_DATA:
 		wordp = stub_get_wordp(chip, command);
 		if (read_write == I2C_SMBUS_WRITE) {
 			*wordp = data->word;
 			dev_dbg(&adap->dev,
 				"smbus word data - addr 0x%02x, wrote 0x%04x at 0x%02x.\n",
 				addr, data->word, command);
 		} else {
 			data->word = *wordp;
 			dev_dbg(&adap->dev,
 				"smbus word data - addr 0x%02x, read  0x%04x at 0x%02x.\n",
 				addr, data->word, command);
 		}

 		ret = 0;
 		break;

 	case I2C_SMBUS_I2C_BLOCK_DATA:
 		/*
 		 * We ignore banks here, because banked chips don't use I2C
 		 * block transfers
 		 */
 		if (data->block[0] > 256 - command)	/* Avoid overrun */
 			data->block[0] = 256 - command;
 		len = data->block[0];
 		if (read_write == I2C_SMBUS_WRITE) {
 			for (i = 0; i < len; i++) {
 				chip->words[command + i] &= 0xff00;
 				chip->words[command + i] |= data->block[1 + i];
 			}
 			dev_dbg(&adap->dev,
 				"i2c block data - addr 0x%02x, wrote %d bytes at 0x%02x.\n",
 				addr, len, command);
 		} else {
 			for (i = 0; i < len; i++) {
 				data->block[1 + i] =
 					chip->words[command + i] & 0xff;
 			}
 			dev_dbg(&adap->dev,
 				"i2c block data - addr 0x%02x, read  %d bytes at 0x%02x.\n",
 				addr, len, command);
 		}

 		ret = 0;
 		break;

 	case I2C_SMBUS_BLOCK_DATA:
 		/*
 		 * We ignore banks here, because chips typically don't use both
 		 * banks and SMBus block transfers
 		 */
 		b = stub_find_block(&adap->dev, chip, command, false);
 		if (read_write == I2C_SMBUS_WRITE) {
 			len = data->block[0];
 			if (len == 0 || len > I2C_SMBUS_BLOCK_MAX) {
 				ret = -EINVAL;
 				break;
 			}
 			if (b == NULL) {
 				b = stub_find_block(&adap->dev, chip, command,
 						    true);
 				if (b == NULL) {
 					ret = -ENOMEM;
 					break;
 				}
 			}
 			/* Largest write sets read block length */
 			if (len > b->len)
 				b->len = len;
 			for (i = 0; i < len; i++)
 				b->block[i] = data->block[i + 1];
 			/* update for byte and word commands */
 			chip->words[command] = (b->block[0] << 8) | b->len;
 			dev_dbg(&adap->dev,
 				"smbus block data - addr 0x%02x, wrote %d bytes at 0x%02x.\n",
 				addr, len, command);
 		} else {
 			if (b == NULL) {
 				dev_dbg(&adap->dev,
 					"SMBus block read command without prior block write not supported\n");
 				ret = -EOPNOTSUPP;
 				break;
 			}
 			len = b->len;
 			data->block[0] = len;
 			for (i = 0; i < len; i++)
 				data->block[i + 1] = b->block[i];
 			dev_dbg(&adap->dev,
 				"smbus block data - addr 0x%02x, read  %d bytes at 0x%02x.\n",
 				addr, len, command);
 		}

 		ret = 0;
 		break;

 	default:
 		dev_dbg(&adap->dev, "Unsupported I2C/SMBus command\n");
 		ret = -EOPNOTSUPP;
 		break;
 	} /* switch (size) */

 	return ret;
 }

 static u32 stub_func(struct i2c_adapter *adapter)
 {
 	return STUB_FUNC_ALL & functionality;
 }

 static const struct i2c_algorithm smbus_algorithm = {
 	.functionality	= stub_func,
 	.smbus_xfer	= stub_xfer,
 };

 static struct i2c_adapter stub_adapter = {
 	.owner		= THIS_MODULE,
 	.class		= I2C_CLASS_HWMON | I2C_CLASS_SPD,
 	.algo		= &smbus_algorithm,
 	.name		= "SMBus stub driver",
 };

 static int __init i2c_stub_allocate_banks(int i)
 {
 	struct stub_chip *chip = stub_chips + i;

 	chip->bank_reg = bank_reg[i];
 	chip->bank_start = bank_start[i];
 	chip->bank_end = bank_end[i];
 	chip->bank_size = bank_end[i] - bank_start[i] + 1;

 	/* We assume that all bits in the mask are contiguous */
 	chip->bank_mask = bank_mask[i];
 	while (!(chip->bank_mask & 1)) {
 		chip->bank_shift++;
 		chip->bank_mask >>= 1;
 	}

 	chip->bank_words = kzalloc(chip->bank_mask * chip->bank_size *
 				   sizeof(u16), GFP_KERNEL);
 	if (!chip->bank_words)
 		return -ENOMEM;

 	pr_debug("Allocated %u banks of %u words each (registers 0x%02x to 0x%02x)\n",
 		 chip->bank_mask, chip->bank_size, chip->bank_start,
 		 chip->bank_end);

 	return 0;
 }

 static void i2c_stub_free(void)
 {
 	int i;

 	for (i = 0; i < stub_chips_nr; i++)
 		kfree(stub_chips[i].bank_words);
 	kfree(stub_chips);
 }

 static int __init i2c_stub_init(void)
 {
 	int i, ret;

 	if (!chip_addr[0]) {
 		pr_err("Please specify a chip address\n");
 		return -ENODEV;
 	}

 	for (i = 0; i < MAX_CHIPS && chip_addr[i]; i++) {
 		if (chip_addr[i] < 0x03 || chip_addr[i] > 0x77) {
 			pr_err("Invalid chip address 0x%02x\n",
 			       chip_addr[i]);
 			return -EINVAL;
 		}

 		pr_info("Virtual chip at 0x%02x\n", chip_addr[i]);
 	}

 	/* Allocate memory for all chips at once */
 	stub_chips_nr = i;
 	stub_chips = kcalloc(stub_chips_nr, sizeof(struct stub_chip),
 			     GFP_KERNEL);
 	if (!stub_chips)
 		return -ENOMEM;

 	for (i = 0; i < stub_chips_nr; i++) {
 		INIT_LIST_HEAD(&stub_chips[i].smbus_blocks);

 		/* Allocate extra memory for banked register ranges */
 		if (bank_mask[i]) {
 			ret = i2c_stub_allocate_banks(i);
 			if (ret)
 				goto fail_free;
 		}
 	}

 	ret = i2c_add_adapter(&stub_adapter);
 	if (ret)
 		goto fail_free;

 	return 0;

  fail_free:
 	i2c_stub_free();
 	return ret;
 }

 static void __exit i2c_stub_exit(void)
 {
 	i2c_del_adapter(&stub_adapter);
 	i2c_stub_free();
 }

 MODULE_AUTHOR("Mark M. Hoffman <mhoffman@lightlink.com>");
 MODULE_DESCRIPTION("I2C stub driver");
 MODULE_LICENSE("GPL");

 module_init(i2c_stub_init);
 module_exit(i2c_stub_exit);
	/*
	i2c-stub.c - I2C/SMBus chip emulator

	Copyright (c) 2004 Mark M. Hoffman <mhoffman@lightlink.com>
	Copyright (C) 2007-2014 Jean Delvare <jdelvare@suse.de>

	This program is free software; you can redistribute it and/or modify
	it under the terms of the GNU General Public License as published by
	the Free Software Foundation; either version 2 of the License, or
	(at your option) any later version.

	This program is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	GNU General Public License for more details.
	*/

	#define DEBUG 1
	#define pr_fmt(fmt) "i2c-stub: " fmt

	#include <linux/errno.h>
	#include <linux/i2c.h>
	#include <linux/init.h>
	#include <linux/kernel.h>
	#include <linux/list.h>
	#include <linux/module.h>
	#include <linux/slab.h>

	#define MAX_CHIPS 10

	/*
	* Support for I2C_FUNC_SMBUS_BLOCK_DATA is disabled by default and must
	* be enabled explicitly by setting the I2C_FUNC_SMBUS_BLOCK_DATA bits
	* in the 'functionality' module parameter.
	*/
	#define STUB_FUNC_DEFAULT \
	(I2C_FUNC_SMBUS_QUICK \| I2C_FUNC_SMBUS_BYTE \| \
	I2C_FUNC_SMBUS_BYTE_DATA \| I2C_FUNC_SMBUS_WORD_DATA \| \
	I2C_FUNC_SMBUS_I2C_BLOCK)

	#define STUB_FUNC_ALL \
	(STUB_FUNC_DEFAULT \| I2C_FUNC_SMBUS_BLOCK_DATA)

	static unsigned short chip_addr[MAX_CHIPS];
	module_param_array(chip_addr, ushort, NULL, S_IRUGO);
	MODULE_PARM_DESC(chip_addr,
	"Chip addresses (up to 10, between 0x03 and 0x77)");

	static unsigned long functionality = STUB_FUNC_DEFAULT;
	module_param(functionality, ulong, S_IRUGO \| S_IWUSR);
	MODULE_PARM_DESC(functionality, "Override functionality bitfield");

	/* Some chips have banked register ranges */

	static u8 bank_reg[MAX_CHIPS];
	module_param_array(bank_reg, byte, NULL, S_IRUGO);
	MODULE_PARM_DESC(bank_reg, "Bank register");

	static u8 bank_mask[MAX_CHIPS];
	module_param_array(bank_mask, byte, NULL, S_IRUGO);
	MODULE_PARM_DESC(bank_mask, "Bank value mask");

	static u8 bank_start[MAX_CHIPS];
	module_param_array(bank_start, byte, NULL, S_IRUGO);
	MODULE_PARM_DESC(bank_start, "First banked register");

	static u8 bank_end[MAX_CHIPS];
	module_param_array(bank_end, byte, NULL, S_IRUGO);
	MODULE_PARM_DESC(bank_end, "Last banked register");

	struct smbus_block_data {
	struct list_head node;
	u8 command;
	u8 len;
	u8 block[I2C_SMBUS_BLOCK_MAX];
	};

	struct stub_chip {
	u8 pointer;
	u16 words[256]; /* Byte operations use the LSB as per SMBus
	specification */
	struct list_head smbus_blocks;

	/* For chips with banks, extra registers are allocated dynamically */
	u8 bank_reg;
	u8 bank_shift;
	u8 bank_mask;
	u8 bank_sel; /* Currently selected bank */
	u8 bank_start;
	u8 bank_end;
	u16 bank_size;
	u16 bank_words; / Room for bank_mask * bank_size registers */
	};

	static struct stub_chip *stub_chips;
	static int stub_chips_nr;

	static struct smbus_block_data stub_find_block(struct device dev,
	struct stub_chip *chip,
	u8 command, bool create)
	{
	struct smbus_block_data b, rb = NULL;

	list_for_each_entry(b, &chip->smbus_blocks, node) {
	if (b->command == command) {
	rb = b;
	break;
	}
	}
	if (rb == NULL && create) {
	rb = devm_kzalloc(dev, sizeof(*rb), GFP_KERNEL);
	if (rb == NULL)
	return rb;
	rb->command = command;
	list_add(&rb->node, &chip->smbus_blocks);
	}
	return rb;
	}

	static u16 stub_get_wordp(struct stub_chip chip, u8 offset)
	{
	if (chip->bank_sel &&
	offset >= chip->bank_start && offset <= chip->bank_end)
	return chip->bank_words +
	(chip->bank_sel - 1) * chip->bank_size +
	offset - chip->bank_start;
	else
	return chip->words + offset;
	}

	/* Return negative errno on error. */
	static s32 stub_xfer(struct i2c_adapter *adap, u16 addr, unsigned short flags,
	char read_write, u8 command, int size, union i2c_smbus_data *data)
	{
	s32 ret;
	int i, len;
	struct stub_chip *chip = NULL;
	struct smbus_block_data *b;
	u16 *wordp;

	/* Search for the right chip */
	for (i = 0; i < stub_chips_nr; i++) {
	if (addr == chip_addr[i]) {
	chip = stub_chips + i;
	break;
	}
	}
	if (!chip)
	return -ENODEV;

	switch (size) {

	case I2C_SMBUS_QUICK:
	dev_dbg(&adap->dev, "smbus quick - addr 0x%02x\n", addr);
	ret = 0;
	break;

	case I2C_SMBUS_BYTE:
	if (read_write == I2C_SMBUS_WRITE) {
	chip->pointer = command;
	dev_dbg(&adap->dev,
	"smbus byte - addr 0x%02x, wrote 0x%02x.\n",
	addr, command);
	} else {
	wordp = stub_get_wordp(chip, chip->pointer++);
	data->byte = *wordp & 0xff;
	dev_dbg(&adap->dev,
	"smbus byte - addr 0x%02x, read 0x%02x.\n",
	addr, data->byte);
	}

	ret = 0;
	break;

	case I2C_SMBUS_BYTE_DATA:
	wordp = stub_get_wordp(chip, command);
	if (read_write == I2C_SMBUS_WRITE) {
	*wordp &= 0xff00;
	*wordp \|= data->byte;
	dev_dbg(&adap->dev,
	"smbus byte data - addr 0x%02x, wrote 0x%02x at 0x%02x.\n",
	addr, data->byte, command);

	/* Set the bank as needed */
	if (chip->bank_words && command == chip->bank_reg) {
	chip->bank_sel =
	(data->byte >> chip->bank_shift)
	& chip->bank_mask;
	dev_dbg(&adap->dev,
	"switching to bank %u.\n",
	chip->bank_sel);
	}
	} else {
	data->byte = *wordp & 0xff;
	dev_dbg(&adap->dev,
	"smbus byte data - addr 0x%02x, read 0x%02x at 0x%02x.\n",
	addr, data->byte, command);
	}
	chip->pointer = command + 1;

	ret = 0;
	break;

	case I2C_SMBUS_WORD_DATA:
	wordp = stub_get_wordp(chip, command);
	if (read_write == I2C_SMBUS_WRITE) {
	*wordp = data->word;
	dev_dbg(&adap->dev,
	"smbus word data - addr 0x%02x, wrote 0x%04x at 0x%02x.\n",
	addr, data->word, command);
	} else {
	data->word = *wordp;
	dev_dbg(&adap->dev,
	"smbus word data - addr 0x%02x, read 0x%04x at 0x%02x.\n",
	addr, data->word, command);
	}

	ret = 0;
	break;

	case I2C_SMBUS_I2C_BLOCK_DATA:
	/*
	* We ignore banks here, because banked chips don't use I2C
	* block transfers
	*/
	if (data->block[0] > 256 - command) /* Avoid overrun */
	data->block[0] = 256 - command;
	len = data->block[0];
	if (read_write == I2C_SMBUS_WRITE) {
	for (i = 0; i < len; i++) {
	chip->words[command + i] &= 0xff00;
	chip->words[command + i] \|= data->block[1 + i];
	}
	dev_dbg(&adap->dev,
	"i2c block data - addr 0x%02x, wrote %d bytes at 0x%02x.\n",
	addr, len, command);
	} else {
	for (i = 0; i < len; i++) {
	data->block[1 + i] =
	chip->words[command + i] & 0xff;
	}
	dev_dbg(&adap->dev,
	"i2c block data - addr 0x%02x, read %d bytes at 0x%02x.\n",
	addr, len, command);
	}

	ret = 0;
	break;

	case I2C_SMBUS_BLOCK_DATA:
	/*
	* We ignore banks here, because chips typically don't use both
	* banks and SMBus block transfers
	*/
	b = stub_find_block(&adap->dev, chip, command, false);
	if (read_write == I2C_SMBUS_WRITE) {
	len = data->block[0];
	if (len == 0 \|\| len > I2C_SMBUS_BLOCK_MAX) {
	ret = -EINVAL;
	break;
	}
	if (b == NULL) {
	b = stub_find_block(&adap->dev, chip, command,
	true);
	if (b == NULL) {
	ret = -ENOMEM;
	break;
	}
	}
	/* Largest write sets read block length */
	if (len > b->len)
	b->len = len;
	for (i = 0; i < len; i++)
	b->block[i] = data->block[i + 1];
	/* update for byte and word commands */
	chip->words[command] = (b->block[0] << 8) \| b->len;
	dev_dbg(&adap->dev,
	"smbus block data - addr 0x%02x, wrote %d bytes at 0x%02x.\n",
	addr, len, command);
	} else {
	if (b == NULL) {
	dev_dbg(&adap->dev,
	"SMBus block read command without prior block write not supported\n");
	ret = -EOPNOTSUPP;
	break;
	}
	len = b->len;
	data->block[0] = len;
	for (i = 0; i < len; i++)
	data->block[i + 1] = b->block[i];
	dev_dbg(&adap->dev,
	"smbus block data - addr 0x%02x, read %d bytes at 0x%02x.\n",
	addr, len, command);
	}

	ret = 0;
	break;

	default:
	dev_dbg(&adap->dev, "Unsupported I2C/SMBus command\n");
	ret = -EOPNOTSUPP;
	break;
	} /* switch (size) */

	return ret;
	}

	static u32 stub_func(struct i2c_adapter *adapter)
	{
	return STUB_FUNC_ALL & functionality;
	}

	static const struct i2c_algorithm smbus_algorithm = {
	.functionality = stub_func,
	.smbus_xfer = stub_xfer,
	};

	static struct i2c_adapter stub_adapter = {
	.owner = THIS_MODULE,
	.class = I2C_CLASS_HWMON \| I2C_CLASS_SPD,
	.algo = &smbus_algorithm,
	.name = "SMBus stub driver",
	};

	static int __init i2c_stub_allocate_banks(int i)
	{
	struct stub_chip *chip = stub_chips + i;

	chip->bank_reg = bank_reg[i];
	chip->bank_start = bank_start[i];
	chip->bank_end = bank_end[i];
	chip->bank_size = bank_end[i] - bank_start[i] + 1;

	/* We assume that all bits in the mask are contiguous */
	chip->bank_mask = bank_mask[i];
	while (!(chip->bank_mask & 1)) {
	chip->bank_shift++;
	chip->bank_mask >>= 1;
	}

	chip->bank_words = kzalloc(chip->bank_mask * chip->bank_size *
	sizeof(u16), GFP_KERNEL);
	if (!chip->bank_words)
	return -ENOMEM;

	pr_debug("Allocated %u banks of %u words each (registers 0x%02x to 0x%02x)\n",
	chip->bank_mask, chip->bank_size, chip->bank_start,
	chip->bank_end);

	return 0;
	}

	static void i2c_stub_free(void)
	{
	int i;

	for (i = 0; i < stub_chips_nr; i++)
	kfree(stub_chips[i].bank_words);
	kfree(stub_chips);
	}

	static int __init i2c_stub_init(void)
	{
	int i, ret;

	if (!chip_addr[0]) {
	pr_err("Please specify a chip address\n");
	return -ENODEV;
	}

	for (i = 0; i < MAX_CHIPS && chip_addr[i]; i++) {
	if (chip_addr[i] < 0x03 \|\| chip_addr[i] > 0x77) {
	pr_err("Invalid chip address 0x%02x\n",
	chip_addr[i]);
	return -EINVAL;
	}

	pr_info("Virtual chip at 0x%02x\n", chip_addr[i]);
	}

	/* Allocate memory for all chips at once */
	stub_chips_nr = i;
	stub_chips = kcalloc(stub_chips_nr, sizeof(struct stub_chip),
	GFP_KERNEL);
	if (!stub_chips)
	return -ENOMEM;

	for (i = 0; i < stub_chips_nr; i++) {
	INIT_LIST_HEAD(&stub_chips[i].smbus_blocks);

	/* Allocate extra memory for banked register ranges */
	if (bank_mask[i]) {
	ret = i2c_stub_allocate_banks(i);
	if (ret)
	goto fail_free;
	}
	}

	ret = i2c_add_adapter(&stub_adapter);
	if (ret)
	goto fail_free;

	return 0;

	fail_free:
	i2c_stub_free();
	return ret;
	}

	static void __exit i2c_stub_exit(void)
	{
	i2c_del_adapter(&stub_adapter);
	i2c_stub_free();
	}

	MODULE_AUTHOR("Mark M. Hoffman <mhoffman@lightlink.com>");
	MODULE_DESCRIPTION("I2C stub driver");
	MODULE_LICENSE("GPL");

	module_init(i2c_stub_init);
	module_exit(i2c_stub_exit);