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 <khali@linux-fr.org>
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/init.h>
21#include <linux/module.h>
22#include <linux/slab.h>
23#include <linux/jiffies.h>
24#include <linux/i2c.h>
25#include <linux/mutex.h>
26
27/* Addresses to scan */
28static const unsigned short normal_i2c[] = { 0x50, 0x51, 0x52, 0x53, 0x54,
29					0x55, 0x56, 0x57, I2C_CLIENT_END };
30
31
32/* Size of EEPROM in bytes */
33#define EEPROM_SIZE		256
34
35/* possible types of eeprom devices */
36enum eeprom_nature {
37	UNKNOWN,
38	VAIO,
39};
40
41/* Each client has this additional data */
42struct eeprom_data {
43	struct mutex update_lock;
44	u8 valid;			/* bitfield, bit!=0 if slice is valid */
45	unsigned long last_updated[8];	/* In jiffies, 8 slices */
46	u8 data[EEPROM_SIZE];		/* Register values */
47	enum eeprom_nature nature;
48};
49
50
51static void eeprom_update_client(struct i2c_client *client, u8 slice)
52{
53	struct eeprom_data *data = i2c_get_clientdata(client);
54	int i;
55
56	mutex_lock(&data->update_lock);
57
58	if (!(data->valid & (1 << slice)) ||
59	    time_after(jiffies, data->last_updated[slice] + 300 * HZ)) {
60		dev_dbg(&client->dev, "Starting eeprom update, slice %u\n", slice);
61
62		if (i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_READ_I2C_BLOCK)) {
63			for (i = slice << 5; i < (slice + 1) << 5; i += 32)
64				if (i2c_smbus_read_i2c_block_data(client, i,
65							32, data->data + i)
66							!= 32)
67					goto exit;
68		} else {
69			for (i = slice << 5; i < (slice + 1) << 5; i += 2) {
70				int word = i2c_smbus_read_word_data(client, i);
71				if (word < 0)
72					goto exit;
73				data->data[i] = word & 0xff;
74				data->data[i + 1] = word >> 8;
75			}
76		}
77		data->last_updated[slice] = jiffies;
78		data->valid |= (1 << slice);
79	}
80exit:
81	mutex_unlock(&data->update_lock);
82}
83
84static ssize_t eeprom_read(struct file *filp, struct kobject *kobj,
85			   struct bin_attribute *bin_attr,
86			   char *buf, loff_t off, size_t count)
87{
88	struct i2c_client *client = to_i2c_client(container_of(kobj, struct device, kobj));
89	struct eeprom_data *data = i2c_get_clientdata(client);
90	u8 slice;
91
92	if (off > EEPROM_SIZE)
93		return 0;
94	if (off + count > EEPROM_SIZE)
95		count = EEPROM_SIZE - off;
96
97	/* Only refresh slices which contain requested bytes */
98	for (slice = off >> 5; slice <= (off + count - 1) >> 5; slice++)
99		eeprom_update_client(client, slice);
100
101	/* Hide Vaio private settings to regular users:
102	   - BIOS passwords: bytes 0x00 to 0x0f
103	   - UUID: bytes 0x10 to 0x1f
104	   - Serial number: 0xc0 to 0xdf */
105	if (data->nature == VAIO && !capable(CAP_SYS_ADMIN)) {
106		int i;
107
108		for (i = 0; i < count; i++) {
109			if ((off + i <= 0x1f) ||
110			    (off + i >= 0xc0 && off + i <= 0xdf))
111				buf[i] = 0;
112			else
113				buf[i] = data->data[off + i];
114		}
115	} else {
116		memcpy(buf, &data->data[off], count);
117	}
118
119	return count;
120}
121
122static struct bin_attribute eeprom_attr = {
123	.attr = {
124		.name = "eeprom",
125		.mode = S_IRUGO,
126	},
127	.size = EEPROM_SIZE,
128	.read = eeprom_read,
129};
130
131/* Return 0 if detection is successful, -ENODEV otherwise */
132static int eeprom_detect(struct i2c_client *client, struct i2c_board_info *info)
133{
134	struct i2c_adapter *adapter = client->adapter;
135
136	/* EDID EEPROMs are often 24C00 EEPROMs, which answer to all
137	   addresses 0x50-0x57, but we only care about 0x50. So decline
138	   attaching to addresses >= 0x51 on DDC buses */
139	if (!(adapter->class & I2C_CLASS_SPD) && client->addr >= 0x51)
140		return -ENODEV;
141
142	/* There are four ways we can read the EEPROM data:
143	   (1) I2C block reads (faster, but unsupported by most adapters)
144	   (2) Word reads (128% overhead)
145	   (3) Consecutive byte reads (88% overhead, unsafe)
146	   (4) Regular byte data reads (265% overhead)
147	   The third and fourth methods are not implemented by this driver
148	   because all known adapters support one of the first two. */
149	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_WORD_DATA)
150	 && !i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_I2C_BLOCK))
151		return -ENODEV;
152
153	strlcpy(info->type, "eeprom", I2C_NAME_SIZE);
154
155	return 0;
156}
157
158static int eeprom_probe(struct i2c_client *client,
159			const struct i2c_device_id *id)
160{
161	struct i2c_adapter *adapter = client->adapter;
162	struct eeprom_data *data;
163	int err;
164
165	if (!(data = kzalloc(sizeof(struct eeprom_data), GFP_KERNEL))) {
166		err = -ENOMEM;
167		goto exit;
168	}
169
170	memset(data->data, 0xff, EEPROM_SIZE);
171	i2c_set_clientdata(client, data);
172	mutex_init(&data->update_lock);
173	data->nature = UNKNOWN;
174
175	/* Detect the Vaio nature of EEPROMs.
176	   We use the "PCG-" or "VGN-" prefix as the signature. */
177	if (client->addr == 0x57
178	 && i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_BYTE_DATA)) {
179		char name[4];
180
181		name[0] = i2c_smbus_read_byte_data(client, 0x80);
182		name[1] = i2c_smbus_read_byte_data(client, 0x81);
183		name[2] = i2c_smbus_read_byte_data(client, 0x82);
184		name[3] = i2c_smbus_read_byte_data(client, 0x83);
185
186		if (!memcmp(name, "PCG-", 4) || !memcmp(name, "VGN-", 4)) {
187			dev_info(&client->dev, "Vaio EEPROM detected, "
188				 "enabling privacy protection\n");
189			data->nature = VAIO;
190		}
191	}
192
193	/* create the sysfs eeprom file */
194	err = sysfs_create_bin_file(&client->dev.kobj, &eeprom_attr);
195	if (err)
196		goto exit_kfree;
197
198	return 0;
199
200exit_kfree:
201	kfree(data);
202exit:
203	return err;
204}
205
206static int eeprom_remove(struct i2c_client *client)
207{
208	sysfs_remove_bin_file(&client->dev.kobj, &eeprom_attr);
209	kfree(i2c_get_clientdata(client));
210
211	return 0;
212}
213
214static const struct i2c_device_id eeprom_id[] = {
215	{ "eeprom", 0 },
216	{ }
217};
218
219static struct i2c_driver eeprom_driver = {
220	.driver = {
221		.name	= "eeprom",
222	},
223	.probe		= eeprom_probe,
224	.remove		= eeprom_remove,
225	.id_table	= eeprom_id,
226
227	.class		= I2C_CLASS_DDC | I2C_CLASS_SPD,
228	.detect		= eeprom_detect,
229	.address_list	= normal_i2c,
230};
231
232module_i2c_driver(eeprom_driver);
233
234MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl> and "
235		"Philip Edelbrock <phil@netroedge.com> and "
236		"Greg Kroah-Hartman <greg@kroah.com>");
237MODULE_DESCRIPTION("I2C EEPROM driver");
238MODULE_LICENSE("GPL");
239