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 You should have received a copy of the GNU General Public License 19 along with this program; if not, write to the Free Software 20 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. 21 */ 22 23 #include <linux/kernel.h> 24 #include <linux/init.h> 25 #include <linux/module.h> 26 #include <linux/slab.h> 27 #include <linux/jiffies.h> 28 #include <linux/i2c.h> 29 #include <linux/mutex.h> 30 31 /* Addresses to scan */ 32 static const unsigned short normal_i2c[] = { 0x50, 0x51, 0x52, 0x53, 0x54, 33 0x55, 0x56, 0x57, I2C_CLIENT_END }; 34 35 /* Insmod parameters */ 36 I2C_CLIENT_INSMOD_1(eeprom); 37 38 39 /* Size of EEPROM in bytes */ 40 #define EEPROM_SIZE 256 41 42 /* possible types of eeprom devices */ 43 enum eeprom_nature { 44 UNKNOWN, 45 VAIO, 46 }; 47 48 /* Each client has this additional data */ 49 struct eeprom_data { 50 struct mutex update_lock; 51 u8 valid; /* bitfield, bit!=0 if slice is valid */ 52 unsigned long last_updated[8]; /* In jiffies, 8 slices */ 53 u8 data[EEPROM_SIZE]; /* Register values */ 54 enum eeprom_nature nature; 55 }; 56 57 58 static void eeprom_update_client(struct i2c_client *client, u8 slice) 59 { 60 struct eeprom_data *data = i2c_get_clientdata(client); 61 int i; 62 63 mutex_lock(&data->update_lock); 64 65 if (!(data->valid & (1 << slice)) || 66 time_after(jiffies, data->last_updated[slice] + 300 * HZ)) { 67 dev_dbg(&client->dev, "Starting eeprom update, slice %u\n", slice); 68 69 if (i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_READ_I2C_BLOCK)) { 70 for (i = slice << 5; i < (slice + 1) << 5; i += 32) 71 if (i2c_smbus_read_i2c_block_data(client, i, 72 32, data->data + i) 73 != 32) 74 goto exit; 75 } else { 76 for (i = slice << 5; i < (slice + 1) << 5; i += 2) { 77 int word = i2c_smbus_read_word_data(client, i); 78 if (word < 0) 79 goto exit; 80 data->data[i] = word & 0xff; 81 data->data[i + 1] = word >> 8; 82 } 83 } 84 data->last_updated[slice] = jiffies; 85 data->valid |= (1 << slice); 86 } 87 exit: 88 mutex_unlock(&data->update_lock); 89 } 90 91 static ssize_t eeprom_read(struct kobject *kobj, struct bin_attribute *bin_attr, 92 char *buf, loff_t off, size_t count) 93 { 94 struct i2c_client *client = to_i2c_client(container_of(kobj, struct device, kobj)); 95 struct eeprom_data *data = i2c_get_clientdata(client); 96 u8 slice; 97 98 if (off > EEPROM_SIZE) 99 return 0; 100 if (off + count > EEPROM_SIZE) 101 count = EEPROM_SIZE - off; 102 103 /* Only refresh slices which contain requested bytes */ 104 for (slice = off >> 5; slice <= (off + count - 1) >> 5; slice++) 105 eeprom_update_client(client, slice); 106 107 /* Hide Vaio private settings to regular users: 108 - BIOS passwords: bytes 0x00 to 0x0f 109 - UUID: bytes 0x10 to 0x1f 110 - Serial number: 0xc0 to 0xdf */ 111 if (data->nature == VAIO && !capable(CAP_SYS_ADMIN)) { 112 int i; 113 114 for (i = 0; i < count; i++) { 115 if ((off + i <= 0x1f) || 116 (off + i >= 0xc0 && off + i <= 0xdf)) 117 buf[i] = 0; 118 else 119 buf[i] = data->data[off + i]; 120 } 121 } else { 122 memcpy(buf, &data->data[off], count); 123 } 124 125 return count; 126 } 127 128 static struct bin_attribute eeprom_attr = { 129 .attr = { 130 .name = "eeprom", 131 .mode = S_IRUGO, 132 }, 133 .size = EEPROM_SIZE, 134 .read = eeprom_read, 135 }; 136 137 /* Return 0 if detection is successful, -ENODEV otherwise */ 138 static int eeprom_detect(struct i2c_client *client, struct i2c_board_info *info) 139 { 140 struct i2c_adapter *adapter = client->adapter; 141 142 /* EDID EEPROMs are often 24C00 EEPROMs, which answer to all 143 addresses 0x50-0x57, but we only care about 0x50. So decline 144 attaching to addresses >= 0x51 on DDC buses */ 145 if (!(adapter->class & I2C_CLASS_SPD) && client->addr >= 0x51) 146 return -ENODEV; 147 148 /* There are four ways we can read the EEPROM data: 149 (1) I2C block reads (faster, but unsupported by most adapters) 150 (2) Word reads (128% overhead) 151 (3) Consecutive byte reads (88% overhead, unsafe) 152 (4) Regular byte data reads (265% overhead) 153 The third and fourth methods are not implemented by this driver 154 because all known adapters support one of the first two. */ 155 if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_WORD_DATA) 156 && !i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_I2C_BLOCK)) 157 return -ENODEV; 158 159 strlcpy(info->type, "eeprom", I2C_NAME_SIZE); 160 161 return 0; 162 } 163 164 static int eeprom_probe(struct i2c_client *client, 165 const struct i2c_device_id *id) 166 { 167 struct i2c_adapter *adapter = client->adapter; 168 struct eeprom_data *data; 169 int err; 170 171 if (!(data = kzalloc(sizeof(struct eeprom_data), GFP_KERNEL))) { 172 err = -ENOMEM; 173 goto exit; 174 } 175 176 memset(data->data, 0xff, EEPROM_SIZE); 177 i2c_set_clientdata(client, data); 178 mutex_init(&data->update_lock); 179 data->nature = UNKNOWN; 180 181 /* Detect the Vaio nature of EEPROMs. 182 We use the "PCG-" or "VGN-" prefix as the signature. */ 183 if (client->addr == 0x57 184 && i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_BYTE_DATA)) { 185 char name[4]; 186 187 name[0] = i2c_smbus_read_byte_data(client, 0x80); 188 name[1] = i2c_smbus_read_byte_data(client, 0x81); 189 name[2] = i2c_smbus_read_byte_data(client, 0x82); 190 name[3] = i2c_smbus_read_byte_data(client, 0x83); 191 192 if (!memcmp(name, "PCG-", 4) || !memcmp(name, "VGN-", 4)) { 193 dev_info(&client->dev, "Vaio EEPROM detected, " 194 "enabling privacy protection\n"); 195 data->nature = VAIO; 196 } 197 } 198 199 /* create the sysfs eeprom file */ 200 err = sysfs_create_bin_file(&client->dev.kobj, &eeprom_attr); 201 if (err) 202 goto exit_kfree; 203 204 return 0; 205 206 exit_kfree: 207 kfree(data); 208 exit: 209 return err; 210 } 211 212 static int eeprom_remove(struct i2c_client *client) 213 { 214 sysfs_remove_bin_file(&client->dev.kobj, &eeprom_attr); 215 kfree(i2c_get_clientdata(client)); 216 217 return 0; 218 } 219 220 static const struct i2c_device_id eeprom_id[] = { 221 { "eeprom", 0 }, 222 { } 223 }; 224 225 static struct i2c_driver eeprom_driver = { 226 .driver = { 227 .name = "eeprom", 228 }, 229 .probe = eeprom_probe, 230 .remove = eeprom_remove, 231 .id_table = eeprom_id, 232 233 .class = I2C_CLASS_DDC | I2C_CLASS_SPD, 234 .detect = eeprom_detect, 235 .address_list = normal_i2c, 236 }; 237 238 static int __init eeprom_init(void) 239 { 240 return i2c_add_driver(&eeprom_driver); 241 } 242 243 static void __exit eeprom_exit(void) 244 { 245 i2c_del_driver(&eeprom_driver); 246 } 247 248 249 MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl> and " 250 "Philip Edelbrock <phil@netroedge.com> and " 251 "Greg Kroah-Hartman <greg@kroah.com>"); 252 MODULE_DESCRIPTION("I2C EEPROM driver"); 253 MODULE_LICENSE("GPL"); 254 255 module_init(eeprom_init); 256 module_exit(eeprom_exit); 257