drivers/misc/eeprom/eeprom.c - arm/linux - Git at Google

 /*
  * Copyright (C) 1998, 1999  Frodo Looijaard <frodol@dds.nl> and
  *                           Philip Edelbrock <phil@netroedge.com>
  * Copyright (C) 2003 Greg Kroah-Hartman <greg@kroah.com>
  * Copyright (C) 2003 IBM Corp.
  * Copyright (C) 2004 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.
  */

 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/device.h>
 #include <linux/capability.h>
 #include <linux/jiffies.h>
 #include <linux/i2c.h>
 #include <linux/mutex.h>

 /* Addresses to scan */
 static const unsigned short normal_i2c[] = { 0x50, 0x51, 0x52, 0x53, 0x54,
 					0x55, 0x56, 0x57, I2C_CLIENT_END };


 /* Size of EEPROM in bytes */
 #define EEPROM_SIZE		256

 /* possible types of eeprom devices */
 enum eeprom_nature {
 	UNKNOWN,
 	VAIO,
 };

 /* Each client has this additional data */
 struct eeprom_data {
 	struct mutex update_lock;
 	u8 valid;			/* bitfield, bit!=0 if slice is valid */
 	unsigned long last_updated[8];	/* In jiffies, 8 slices */
 	u8 data[EEPROM_SIZE];		/* Register values */
 	enum eeprom_nature nature;
 };


 static void eeprom_update_client(struct i2c_client *client, u8 slice)
 {
 	struct eeprom_data *data = i2c_get_clientdata(client);
 	int i;

 	mutex_lock(&data->update_lock);

 	if (!(data->valid & (1 << slice)) ||
 	    time_after(jiffies, data->last_updated[slice] + 300 * HZ)) {
 		dev_dbg(&client->dev, "Starting eeprom update, slice %u\n", slice);

 		if (i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_READ_I2C_BLOCK)) {
 			for (i = slice << 5; i < (slice + 1) << 5; i += 32)
 				if (i2c_smbus_read_i2c_block_data(client, i,
 							32, data->data + i)
 							!= 32)
 					goto exit;
 		} else {
 			for (i = slice << 5; i < (slice + 1) << 5; i += 2) {
 				int word = i2c_smbus_read_word_data(client, i);
 				if (word < 0)
 					goto exit;
 				data->data[i] = word & 0xff;
 				data->data[i + 1] = word >> 8;
 			}
 		}
 		data->last_updated[slice] = jiffies;
 		data->valid |= (1 << slice);
 	}
 exit:
 	mutex_unlock(&data->update_lock);
 }

 static ssize_t eeprom_read(struct file *filp, struct kobject *kobj,
 			   struct bin_attribute *bin_attr,
 			   char *buf, loff_t off, size_t count)
 {
 	struct i2c_client *client = to_i2c_client(kobj_to_dev(kobj));
 	struct eeprom_data *data = i2c_get_clientdata(client);
 	u8 slice;

 	/* Only refresh slices which contain requested bytes */
 	for (slice = off >> 5; slice <= (off + count - 1) >> 5; slice++)
 		eeprom_update_client(client, slice);

 	/* Hide Vaio private settings to regular users:
 	   - BIOS passwords: bytes 0x00 to 0x0f
 	   - UUID: bytes 0x10 to 0x1f
 	   - Serial number: 0xc0 to 0xdf */
 	if (data->nature == VAIO && !capable(CAP_SYS_ADMIN)) {
 		int i;

 		for (i = 0; i < count; i++) {
 			if ((off + i <= 0x1f) ||
 			    (off + i >= 0xc0 && off + i <= 0xdf))
 				buf[i] = 0;
 			else
 				buf[i] = data->data[off + i];
 		}
 	} else {
 		memcpy(buf, &data->data[off], count);
 	}

 	return count;
 }

 static const struct bin_attribute eeprom_attr = {
 	.attr = {
 		.name = "eeprom",
 		.mode = S_IRUGO,
 	},
 	.size = EEPROM_SIZE,
 	.read = eeprom_read,
 };

 /* Return 0 if detection is successful, -ENODEV otherwise */
 static int eeprom_detect(struct i2c_client *client, struct i2c_board_info *info)
 {
 	struct i2c_adapter *adapter = client->adapter;

 	/* EDID EEPROMs are often 24C00 EEPROMs, which answer to all
 	   addresses 0x50-0x57, but we only care about 0x50. So decline
 	   attaching to addresses >= 0x51 on DDC buses */
 	if (!(adapter->class & I2C_CLASS_SPD) && client->addr >= 0x51)
 		return -ENODEV;

 	/* There are four ways we can read the EEPROM data:
 	   (1) I2C block reads (faster, but unsupported by most adapters)
 	   (2) Word reads (128% overhead)
 	   (3) Consecutive byte reads (88% overhead, unsafe)
 	   (4) Regular byte data reads (265% overhead)
 	   The third and fourth methods are not implemented by this driver
 	   because all known adapters support one of the first two. */
 	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_WORD_DATA)
 	 && !i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_I2C_BLOCK))
 		return -ENODEV;

 	strlcpy(info->type, "eeprom", I2C_NAME_SIZE);

 	return 0;
 }

 static int eeprom_probe(struct i2c_client *client,
 			const struct i2c_device_id *id)
 {
 	struct i2c_adapter *adapter = client->adapter;
 	struct eeprom_data *data;

 	data = devm_kzalloc(&client->dev, sizeof(struct eeprom_data),
 			    GFP_KERNEL);
 	if (!data)
 		return -ENOMEM;

 	memset(data->data, 0xff, EEPROM_SIZE);
 	i2c_set_clientdata(client, data);
 	mutex_init(&data->update_lock);
 	data->nature = UNKNOWN;

 	/* Detect the Vaio nature of EEPROMs.
 	   We use the "PCG-" or "VGN-" prefix as the signature. */
 	if (client->addr == 0x57
 	 && i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_BYTE_DATA)) {
 		char name[4];

 		name[0] = i2c_smbus_read_byte_data(client, 0x80);
 		name[1] = i2c_smbus_read_byte_data(client, 0x81);
 		name[2] = i2c_smbus_read_byte_data(client, 0x82);
 		name[3] = i2c_smbus_read_byte_data(client, 0x83);

 		if (!memcmp(name, "PCG-", 4) || !memcmp(name, "VGN-", 4)) {
 			dev_info(&client->dev, "Vaio EEPROM detected, "
 				 "enabling privacy protection\n");
 			data->nature = VAIO;
 		}
 	}

 	/* create the sysfs eeprom file */
 	return sysfs_create_bin_file(&client->dev.kobj, &eeprom_attr);
 }

 static int eeprom_remove(struct i2c_client *client)
 {
 	sysfs_remove_bin_file(&client->dev.kobj, &eeprom_attr);

 	return 0;
 }

 static const struct i2c_device_id eeprom_id[] = {
 	{ "eeprom", 0 },
 	{ }
 };

 static struct i2c_driver eeprom_driver = {
 	.driver = {
 		.name	= "eeprom",
 	},
 	.probe		= eeprom_probe,
 	.remove		= eeprom_remove,
 	.id_table	= eeprom_id,

 	.class		= I2C_CLASS_DDC | I2C_CLASS_SPD,
 	.detect		= eeprom_detect,
 	.address_list	= normal_i2c,
 };

 module_i2c_driver(eeprom_driver);

 MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl> and "
 		"Philip Edelbrock <phil@netroedge.com> and "
 		"Greg Kroah-Hartman <greg@kroah.com>");
 MODULE_DESCRIPTION("I2C EEPROM driver");
 MODULE_LICENSE("GPL");
	/*
	* Copyright (C) 1998, 1999 Frodo Looijaard <frodol@dds.nl> and
	* Philip Edelbrock <phil@netroedge.com>
	* Copyright (C) 2003 Greg Kroah-Hartman <greg@kroah.com>
	* Copyright (C) 2003 IBM Corp.
	* Copyright (C) 2004 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.
	*/

	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/device.h>
	#include <linux/capability.h>
	#include <linux/jiffies.h>
	#include <linux/i2c.h>
	#include <linux/mutex.h>

	/* Addresses to scan */
	static const unsigned short normal_i2c[] = { 0x50, 0x51, 0x52, 0x53, 0x54,
	0x55, 0x56, 0x57, I2C_CLIENT_END };


	/* Size of EEPROM in bytes */
	#define EEPROM_SIZE 256

	/* possible types of eeprom devices */
	enum eeprom_nature {
	UNKNOWN,
	VAIO,
	};

	/* Each client has this additional data */
	struct eeprom_data {
	struct mutex update_lock;
	u8 valid; /* bitfield, bit!=0 if slice is valid */
	unsigned long last_updated[8]; /* In jiffies, 8 slices */
	u8 data[EEPROM_SIZE]; /* Register values */
	enum eeprom_nature nature;
	};


	static void eeprom_update_client(struct i2c_client *client, u8 slice)
	{
	struct eeprom_data *data = i2c_get_clientdata(client);
	int i;

	mutex_lock(&data->update_lock);

	if (!(data->valid & (1 << slice)) \|\|
	time_after(jiffies, data->last_updated[slice] + 300 * HZ)) {
	dev_dbg(&client->dev, "Starting eeprom update, slice %u\n", slice);

	if (i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_READ_I2C_BLOCK)) {
	for (i = slice << 5; i < (slice + 1) << 5; i += 32)
	if (i2c_smbus_read_i2c_block_data(client, i,
	32, data->data + i)
	!= 32)
	goto exit;
	} else {
	for (i = slice << 5; i < (slice + 1) << 5; i += 2) {
	int word = i2c_smbus_read_word_data(client, i);
	if (word < 0)
	goto exit;
	data->data[i] = word & 0xff;
	data->data[i + 1] = word >> 8;
	}
	}
	data->last_updated[slice] = jiffies;
	data->valid \|= (1 << slice);
	}
	exit:
	mutex_unlock(&data->update_lock);
	}

	static ssize_t eeprom_read(struct file filp, struct kobject kobj,
	struct bin_attribute *bin_attr,
	char *buf, loff_t off, size_t count)
	{
	struct i2c_client *client = to_i2c_client(kobj_to_dev(kobj));
	struct eeprom_data *data = i2c_get_clientdata(client);
	u8 slice;

	/* Only refresh slices which contain requested bytes */
	for (slice = off >> 5; slice <= (off + count - 1) >> 5; slice++)
	eeprom_update_client(client, slice);

	/* Hide Vaio private settings to regular users:
	- BIOS passwords: bytes 0x00 to 0x0f
	- UUID: bytes 0x10 to 0x1f
	- Serial number: 0xc0 to 0xdf */
	if (data->nature == VAIO && !capable(CAP_SYS_ADMIN)) {
	int i;

	for (i = 0; i < count; i++) {
	if ((off + i <= 0x1f) \|\|
	(off + i >= 0xc0 && off + i <= 0xdf))
	buf[i] = 0;
	else
	buf[i] = data->data[off + i];
	}
	} else {
	memcpy(buf, &data->data[off], count);
	}

	return count;
	}

	static const struct bin_attribute eeprom_attr = {
	.attr = {
	.name = "eeprom",
	.mode = S_IRUGO,
	},
	.size = EEPROM_SIZE,
	.read = eeprom_read,
	};

	/* Return 0 if detection is successful, -ENODEV otherwise */
	static int eeprom_detect(struct i2c_client client, struct i2c_board_info info)
	{
	struct i2c_adapter *adapter = client->adapter;

	/* EDID EEPROMs are often 24C00 EEPROMs, which answer to all
	addresses 0x50-0x57, but we only care about 0x50. So decline
	attaching to addresses >= 0x51 on DDC buses */
	if (!(adapter->class & I2C_CLASS_SPD) && client->addr >= 0x51)
	return -ENODEV;

	/* There are four ways we can read the EEPROM data:
	(1) I2C block reads (faster, but unsupported by most adapters)
	(2) Word reads (128% overhead)
	(3) Consecutive byte reads (88% overhead, unsafe)
	(4) Regular byte data reads (265% overhead)
	The third and fourth methods are not implemented by this driver
	because all known adapters support one of the first two. */
	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_WORD_DATA)
	&& !i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_I2C_BLOCK))
	return -ENODEV;

	strlcpy(info->type, "eeprom", I2C_NAME_SIZE);

	return 0;
	}

	static int eeprom_probe(struct i2c_client *client,
	const struct i2c_device_id *id)
	{
	struct i2c_adapter *adapter = client->adapter;
	struct eeprom_data *data;

	data = devm_kzalloc(&client->dev, sizeof(struct eeprom_data),
	GFP_KERNEL);
	if (!data)
	return -ENOMEM;

	memset(data->data, 0xff, EEPROM_SIZE);
	i2c_set_clientdata(client, data);
	mutex_init(&data->update_lock);
	data->nature = UNKNOWN;

	/* Detect the Vaio nature of EEPROMs.
	We use the "PCG-" or "VGN-" prefix as the signature. */
	if (client->addr == 0x57
	&& i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_BYTE_DATA)) {
	char name[4];

	name[0] = i2c_smbus_read_byte_data(client, 0x80);
	name[1] = i2c_smbus_read_byte_data(client, 0x81);
	name[2] = i2c_smbus_read_byte_data(client, 0x82);
	name[3] = i2c_smbus_read_byte_data(client, 0x83);

	if (!memcmp(name, "PCG-", 4) \|\| !memcmp(name, "VGN-", 4)) {
	dev_info(&client->dev, "Vaio EEPROM detected, "
	"enabling privacy protection\n");
	data->nature = VAIO;
	}
	}

	/* create the sysfs eeprom file */
	return sysfs_create_bin_file(&client->dev.kobj, &eeprom_attr);
	}

	static int eeprom_remove(struct i2c_client *client)
	{
	sysfs_remove_bin_file(&client->dev.kobj, &eeprom_attr);

	return 0;
	}

	static const struct i2c_device_id eeprom_id[] = {
	{ "eeprom", 0 },
	{ }
	};

	static struct i2c_driver eeprom_driver = {
	.driver = {
	.name = "eeprom",
	},
	.probe = eeprom_probe,
	.remove = eeprom_remove,
	.id_table = eeprom_id,

	.class = I2C_CLASS_DDC \| I2C_CLASS_SPD,
	.detect = eeprom_detect,
	.address_list = normal_i2c,
	};

	module_i2c_driver(eeprom_driver);

	MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl> and "
	"Philip Edelbrock <phil@netroedge.com> and "
	"Greg Kroah-Hartman <greg@kroah.com>");
	MODULE_DESCRIPTION("I2C EEPROM driver");
	MODULE_LICENSE("GPL");