1/*
  2 * Copyright (C) 1998, 1999  Frodo Looijaard <frodol@dds.nl> and
  3 *                           Philip Edelbrock <phil@netroedge.com>
  4 * Copyright (C) 2003 Greg Kroah-Hartman <greg@kroah.com>
  5 * Copyright (C) 2003 IBM Corp.
  6 * Copyright (C) 2004 Jean Delvare <jdelvare@suse.de>
  7 *
  8 * This program is free software; you can redistribute it and/or modify
  9 * it under the terms of the GNU General Public License as published by
 10 * the Free Software Foundation; either version 2 of the License, or
 11 * (at your option) any later version.
 12 *
 13 * This program is distributed in the hope that it will be useful,
 14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 16 * GNU General Public License for more details.
 17 */
 18
 19#include <linux/kernel.h>
 20#include <linux/module.h>
 21#include <linux/device.h>
 22#include <linux/jiffies.h>
 23#include <linux/i2c.h>
 24#include <linux/mutex.h>
 25
 26/* Addresses to scan */
 27static const unsigned short normal_i2c[] = { 0x50, 0x51, 0x52, 0x53, 0x54,
 28					0x55, 0x56, 0x57, I2C_CLIENT_END };
 29
 30
 31/* Size of EEPROM in bytes */
 32#define EEPROM_SIZE		256
 33
 34/* possible types of eeprom devices */
 35enum eeprom_nature {
 36	UNKNOWN,
 37	VAIO,
 38};
 39
 40/* Each client has this additional data */
 41struct eeprom_data {
 42	struct mutex update_lock;
 43	u8 valid;			/* bitfield, bit!=0 if slice is valid */
 44	unsigned long last_updated[8];	/* In jiffies, 8 slices */
 45	u8 data[EEPROM_SIZE];		/* Register values */
 46	enum eeprom_nature nature;
 47};
 48
 49
 50static void eeprom_update_client(struct i2c_client *client, u8 slice)
 51{
 52	struct eeprom_data *data = i2c_get_clientdata(client);
 53	int i;
 54
 55	mutex_lock(&data->update_lock);
 56
 57	if (!(data->valid & (1 << slice)) ||
 58	    time_after(jiffies, data->last_updated[slice] + 300 * HZ)) {
 59		dev_dbg(&client->dev, "Starting eeprom update, slice %u\n", slice);
 60
 61		if (i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_READ_I2C_BLOCK)) {
 62			for (i = slice << 5; i < (slice + 1) << 5; i += 32)
 63				if (i2c_smbus_read_i2c_block_data(client, i,
 64							32, data->data + i)
 65							!= 32)
 66					goto exit;
 67		} else {
 68			for (i = slice << 5; i < (slice + 1) << 5; i += 2) {
 69				int word = i2c_smbus_read_word_data(client, i);
 70				if (word < 0)
 71					goto exit;
 72				data->data[i] = word & 0xff;
 73				data->data[i + 1] = word >> 8;
 74			}
 75		}
 76		data->last_updated[slice] = jiffies;
 77		data->valid |= (1 << slice);
 78	}
 79exit:
 80	mutex_unlock(&data->update_lock);
 81}
 82
 83static ssize_t eeprom_read(struct file *filp, struct kobject *kobj,
 84			   struct bin_attribute *bin_attr,
 85			   char *buf, loff_t off, size_t count)
 86{
 87	struct i2c_client *client = to_i2c_client(kobj_to_dev(kobj));
 88	struct eeprom_data *data = i2c_get_clientdata(client);
 89	u8 slice;
 90
 91	/* Only refresh slices which contain requested bytes */
 92	for (slice = off >> 5; slice <= (off + count - 1) >> 5; slice++)
 93		eeprom_update_client(client, slice);
 94
 95	/* Hide Vaio private settings to regular users:
 96	   - BIOS passwords: bytes 0x00 to 0x0f
 97	   - UUID: bytes 0x10 to 0x1f
 98	   - Serial number: 0xc0 to 0xdf */
 99	if (data->nature == VAIO && !capable(CAP_SYS_ADMIN)) {
100		int i;
101
102		for (i = 0; i < count; i++) {
103			if ((off + i <= 0x1f) ||
104			    (off + i >= 0xc0 && off + i <= 0xdf))
105				buf[i] = 0;
106			else
107				buf[i] = data->data[off + i];
108		}
109	} else {
110		memcpy(buf, &data->data[off], count);
111	}
112
113	return count;
114}
115
116static struct bin_attribute eeprom_attr = {
117	.attr = {
118		.name = "eeprom",
119		.mode = S_IRUGO,
120	},
121	.size = EEPROM_SIZE,
122	.read = eeprom_read,
123};
124
125/* Return 0 if detection is successful, -ENODEV otherwise */
126static int eeprom_detect(struct i2c_client *client, struct i2c_board_info *info)
127{
128	struct i2c_adapter *adapter = client->adapter;
129
130	/* EDID EEPROMs are often 24C00 EEPROMs, which answer to all
131	   addresses 0x50-0x57, but we only care about 0x50. So decline
132	   attaching to addresses >= 0x51 on DDC buses */
133	if (!(adapter->class & I2C_CLASS_SPD) && client->addr >= 0x51)
134		return -ENODEV;
135
136	/* There are four ways we can read the EEPROM data:
137	   (1) I2C block reads (faster, but unsupported by most adapters)
138	   (2) Word reads (128% overhead)
139	   (3) Consecutive byte reads (88% overhead, unsafe)
140	   (4) Regular byte data reads (265% overhead)
141	   The third and fourth methods are not implemented by this driver
142	   because all known adapters support one of the first two. */
143	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_WORD_DATA)
144	 && !i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_I2C_BLOCK))
145		return -ENODEV;
146
147	strlcpy(info->type, "eeprom", I2C_NAME_SIZE);
148
149	return 0;
150}
151
152static int eeprom_probe(struct i2c_client *client,
153			const struct i2c_device_id *id)
154{
155	struct i2c_adapter *adapter = client->adapter;
156	struct eeprom_data *data;
157
158	data = devm_kzalloc(&client->dev, sizeof(struct eeprom_data),
159			    GFP_KERNEL);
160	if (!data)
161		return -ENOMEM;
162
163	memset(data->data, 0xff, EEPROM_SIZE);
164	i2c_set_clientdata(client, data);
165	mutex_init(&data->update_lock);
166	data->nature = UNKNOWN;
167
168	/* Detect the Vaio nature of EEPROMs.
169	   We use the "PCG-" or "VGN-" prefix as the signature. */
170	if (client->addr == 0x57
171	 && i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_BYTE_DATA)) {
172		char name[4];
173
174		name[0] = i2c_smbus_read_byte_data(client, 0x80);
175		name[1] = i2c_smbus_read_byte_data(client, 0x81);
176		name[2] = i2c_smbus_read_byte_data(client, 0x82);
177		name[3] = i2c_smbus_read_byte_data(client, 0x83);
178
179		if (!memcmp(name, "PCG-", 4) || !memcmp(name, "VGN-", 4)) {
180			dev_info(&client->dev, "Vaio EEPROM detected, "
181				 "enabling privacy protection\n");
182			data->nature = VAIO;
183		}
184	}
185
186	/* create the sysfs eeprom file */
187	return sysfs_create_bin_file(&client->dev.kobj, &eeprom_attr);
188}
189
190static int eeprom_remove(struct i2c_client *client)
191{
192	sysfs_remove_bin_file(&client->dev.kobj, &eeprom_attr);
193
194	return 0;
195}
196
197static const struct i2c_device_id eeprom_id[] = {
198	{ "eeprom", 0 },
199	{ }
200};
201
202static struct i2c_driver eeprom_driver = {
203	.driver = {
204		.name	= "eeprom",
205	},
206	.probe		= eeprom_probe,
207	.remove		= eeprom_remove,
208	.id_table	= eeprom_id,
209
210	.class		= I2C_CLASS_DDC | I2C_CLASS_SPD,
211	.detect		= eeprom_detect,
212	.address_list	= normal_i2c,
213};
214
215module_i2c_driver(eeprom_driver);
216
217MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl> and "
218		"Philip Edelbrock <phil@netroedge.com> and "
219		"Greg Kroah-Hartman <greg@kroah.com>");
220MODULE_DESCRIPTION("I2C EEPROM driver");
221MODULE_LICENSE("GPL");