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 */ 28 static 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 */ 36 enum eeprom_nature { 37 UNKNOWN, 38 VAIO, 39 }; 40 41 /* Each client has this additional data */ 42 struct 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 51 static 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 } 80 exit: 81 mutex_unlock(&data->update_lock); 82 } 83 84 static 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 } 121 122 static 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 */ 132 static 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 } 157 158 static 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; 199 200 exit_kfree: 201 kfree(data); 202 exit: 203 return err; 204 } 205 206 static 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 } 213 214 static const struct i2c_device_id eeprom_id[] = { 215 { "eeprom", 0 }, 216 { } 217 }; 218 219 static 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 }; 231 232 module_i2c_driver(eeprom_driver); 233 234 MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl> and " 235 "Philip Edelbrock <phil@netroedge.com> and " 236 "Greg Kroah-Hartman <greg@kroah.com>"); 237 MODULE_DESCRIPTION("I2C EEPROM driver"); 238 MODULE_LICENSE("GPL"); 239