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(container_of(kobj, struct device, kobj));
88	struct eeprom_data *data = i2c_get_clientdata(client);
89	u8 slice;
90
91	if (off > EEPROM_SIZE)
92		return 0;
93	if (off + count > EEPROM_SIZE)
94		count = EEPROM_SIZE - off;
95
96	/* Only refresh slices which contain requested bytes */
97	for (slice = off >> 5; slice <= (off + count - 1) >> 5; slice++)
98		eeprom_update_client(client, slice);
99
100	/* Hide Vaio private settings to regular users:
101	   - BIOS passwords: bytes 0x00 to 0x0f
102	   - UUID: bytes 0x10 to 0x1f
103	   - Serial number: 0xc0 to 0xdf */
104	if (data->nature == VAIO && !capable(CAP_SYS_ADMIN)) {
105		int i;
106
107		for (i = 0; i < count; i++) {
108			if ((off + i <= 0x1f) ||
109			    (off + i >= 0xc0 && off + i <= 0xdf))
110				buf[i] = 0;
111			else
112				buf[i] = data->data[off + i];
113		}
114	} else {
115		memcpy(buf, &data->data[off], count);
116	}
117
118	return count;
119}
120
121static struct bin_attribute eeprom_attr = {
122	.attr = {
123		.name = "eeprom",
124		.mode = S_IRUGO,
125	},
126	.size = EEPROM_SIZE,
127	.read = eeprom_read,
128};
129
130/* Return 0 if detection is successful, -ENODEV otherwise */
131static int eeprom_detect(struct i2c_client *client, struct i2c_board_info *info)
132{
133	struct i2c_adapter *adapter = client->adapter;
134
135	/* EDID EEPROMs are often 24C00 EEPROMs, which answer to all
136	   addresses 0x50-0x57, but we only care about 0x50. So decline
137	   attaching to addresses >= 0x51 on DDC buses */
138	if (!(adapter->class & I2C_CLASS_SPD) && client->addr >= 0x51)
139		return -ENODEV;
140
141	/* There are four ways we can read the EEPROM data:
142	   (1) I2C block reads (faster, but unsupported by most adapters)
143	   (2) Word reads (128% overhead)
144	   (3) Consecutive byte reads (88% overhead, unsafe)
145	   (4) Regular byte data reads (265% overhead)
146	   The third and fourth methods are not implemented by this driver
147	   because all known adapters support one of the first two. */
148	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_WORD_DATA)
149	 && !i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_I2C_BLOCK))
150		return -ENODEV;
151
152	strlcpy(info->type, "eeprom", I2C_NAME_SIZE);
153
154	return 0;
155}
156
157static int eeprom_probe(struct i2c_client *client,
158			const struct i2c_device_id *id)
159{
160	struct i2c_adapter *adapter = client->adapter;
161	struct eeprom_data *data;
162
163	data = devm_kzalloc(&client->dev, sizeof(struct eeprom_data),
164			    GFP_KERNEL);
165	if (!data)
166		return -ENOMEM;
167
168	memset(data->data, 0xff, EEPROM_SIZE);
169	i2c_set_clientdata(client, data);
170	mutex_init(&data->update_lock);
171	data->nature = UNKNOWN;
172
173	/* Detect the Vaio nature of EEPROMs.
174	   We use the "PCG-" or "VGN-" prefix as the signature. */
175	if (client->addr == 0x57
176	 && i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_BYTE_DATA)) {
177		char name[4];
178
179		name[0] = i2c_smbus_read_byte_data(client, 0x80);
180		name[1] = i2c_smbus_read_byte_data(client, 0x81);
181		name[2] = i2c_smbus_read_byte_data(client, 0x82);
182		name[3] = i2c_smbus_read_byte_data(client, 0x83);
183
184		if (!memcmp(name, "PCG-", 4) || !memcmp(name, "VGN-", 4)) {
185			dev_info(&client->dev, "Vaio EEPROM detected, "
186				 "enabling privacy protection\n");
187			data->nature = VAIO;
188		}
189	}
190
191	/* create the sysfs eeprom file */
192	return sysfs_create_bin_file(&client->dev.kobj, &eeprom_attr);
193}
194
195static int eeprom_remove(struct i2c_client *client)
196{
197	sysfs_remove_bin_file(&client->dev.kobj, &eeprom_attr);
198
199	return 0;
200}
201
202static const struct i2c_device_id eeprom_id[] = {
203	{ "eeprom", 0 },
204	{ }
205};
206
207static struct i2c_driver eeprom_driver = {
208	.driver = {
209		.name	= "eeprom",
210	},
211	.probe		= eeprom_probe,
212	.remove		= eeprom_remove,
213	.id_table	= eeprom_id,
214
215	.class		= I2C_CLASS_DDC | I2C_CLASS_SPD,
216	.detect		= eeprom_detect,
217	.address_list	= normal_i2c,
218};
219
220module_i2c_driver(eeprom_driver);
221
222MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl> and "
223		"Philip Edelbrock <phil@netroedge.com> and "
224		"Greg Kroah-Hartman <greg@kroah.com>");
225MODULE_DESCRIPTION("I2C EEPROM driver");
226MODULE_LICENSE("GPL");
227