Linux 4.2.1
[linux/fpc-iii.git] / drivers / misc / eeprom / eeprom.c
blobb432873def96b5f489a50279205b0df0c7070453
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>
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.
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.
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>
26 /* Addresses to scan */
27 static const unsigned short normal_i2c[] = { 0x50, 0x51, 0x52, 0x53, 0x54,
28 0x55, 0x56, 0x57, I2C_CLIENT_END };
31 /* Size of EEPROM in bytes */
32 #define EEPROM_SIZE 256
34 /* possible types of eeprom devices */
35 enum eeprom_nature {
36 UNKNOWN,
37 VAIO,
40 /* Each client has this additional data */
41 struct 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;
50 static void eeprom_update_client(struct i2c_client *client, u8 slice)
52 struct eeprom_data *data = i2c_get_clientdata(client);
53 int i;
55 mutex_lock(&data->update_lock);
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);
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;
76 data->last_updated[slice] = jiffies;
77 data->valid |= (1 << slice);
79 exit:
80 mutex_unlock(&data->update_lock);
83 static 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)
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;
91 if (off > EEPROM_SIZE)
92 return 0;
93 if (off + count > EEPROM_SIZE)
94 count = EEPROM_SIZE - off;
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);
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;
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];
114 } else {
115 memcpy(buf, &data->data[off], count);
118 return count;
121 static struct bin_attribute eeprom_attr = {
122 .attr = {
123 .name = "eeprom",
124 .mode = S_IRUGO,
126 .size = EEPROM_SIZE,
127 .read = eeprom_read,
130 /* Return 0 if detection is successful, -ENODEV otherwise */
131 static int eeprom_detect(struct i2c_client *client, struct i2c_board_info *info)
133 struct i2c_adapter *adapter = client->adapter;
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;
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;
152 strlcpy(info->type, "eeprom", I2C_NAME_SIZE);
154 return 0;
157 static int eeprom_probe(struct i2c_client *client,
158 const struct i2c_device_id *id)
160 struct i2c_adapter *adapter = client->adapter;
161 struct eeprom_data *data;
163 data = devm_kzalloc(&client->dev, sizeof(struct eeprom_data),
164 GFP_KERNEL);
165 if (!data)
166 return -ENOMEM;
168 memset(data->data, 0xff, EEPROM_SIZE);
169 i2c_set_clientdata(client, data);
170 mutex_init(&data->update_lock);
171 data->nature = UNKNOWN;
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];
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);
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;
191 /* create the sysfs eeprom file */
192 return sysfs_create_bin_file(&client->dev.kobj, &eeprom_attr);
195 static int eeprom_remove(struct i2c_client *client)
197 sysfs_remove_bin_file(&client->dev.kobj, &eeprom_attr);
199 return 0;
202 static const struct i2c_device_id eeprom_id[] = {
203 { "eeprom", 0 },
207 static struct i2c_driver eeprom_driver = {
208 .driver = {
209 .name = "eeprom",
211 .probe = eeprom_probe,
212 .remove = eeprom_remove,
213 .id_table = eeprom_id,
215 .class = I2C_CLASS_DDC | I2C_CLASS_SPD,
216 .detect = eeprom_detect,
217 .address_list = normal_i2c,
220 module_i2c_driver(eeprom_driver);
222 MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl> and "
223 "Philip Edelbrock <phil@netroedge.com> and "
224 "Greg Kroah-Hartman <greg@kroah.com>");
225 MODULE_DESCRIPTION("I2C EEPROM driver");
226 MODULE_LICENSE("GPL");