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