aboutsummaryrefslogtreecommitdiff
path: root/drivers/misc/eeprom/eeprom.c
blob: 3dc5e3db2c128191479f22da63e76d3e48075485 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
/*
    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 <khali@linux-fr.org>

    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.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/slab.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 };

/* Insmod parameters */
I2C_CLIENT_INSMOD_1(eeprom);


/* 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 kobject *kobj, struct bin_attribute *bin_attr,
			   char *buf, loff_t off, size_t count)
{
	struct i2c_client *client = to_i2c_client(container_of(kobj, struct device, kobj));
	struct eeprom_data *data = i2c_get_clientdata(client);
	u8 slice;

	if (off > EEPROM_SIZE)
		return 0;
	if (off + count > EEPROM_SIZE)
		count = EEPROM_SIZE - off;

	/* 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 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;
	int err;

	if (!(data = kzalloc(sizeof(struct eeprom_data), GFP_KERNEL))) {
		err = -ENOMEM;
		goto exit;
	}

	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 */
	err = sysfs_create_bin_file(&client->dev.kobj, &eeprom_attr);
	if (err)
		goto exit_kfree;

	return 0;

exit_kfree:
	kfree(data);
exit:
	return err;
}

static int eeprom_remove(struct i2c_client *client)
{
	sysfs_remove_bin_file(&client->dev.kobj, &eeprom_attr);
	kfree(i2c_get_clientdata(client));

	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,
};

static int __init eeprom_init(void)
{
	return i2c_add_driver(&eeprom_driver);
}

static void __exit eeprom_exit(void)
{
	i2c_del_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");

module_init(eeprom_init);
module_exit(eeprom_exit);