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> 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/module.h> 21 #include <linux/device.h> 22 #include <linux/capability.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(kobj_to_dev(kobj)); 89 struct eeprom_data *data = i2c_get_clientdata(client); 90 u8 slice; 91 92 /* Only refresh slices which contain requested bytes */ 93 for (slice = off >> 5; slice <= (off + count - 1) >> 5; slice++) 94 eeprom_update_client(client, slice); 95 96 /* Hide Vaio private settings to regular users: 97 - BIOS passwords: bytes 0x00 to 0x0f 98 - UUID: bytes 0x10 to 0x1f 99 - Serial number: 0xc0 to 0xdf */ 100 if (data->nature == VAIO && !capable(CAP_SYS_ADMIN)) { 101 int i; 102 103 for (i = 0; i < count; i++) { 104 if ((off + i <= 0x1f) || 105 (off + i >= 0xc0 && off + i <= 0xdf)) 106 buf[i] = 0; 107 else 108 buf[i] = data->data[off + i]; 109 } 110 } else { 111 memcpy(buf, &data->data[off], count); 112 } 113 114 return count; 115 } 116 117 static const struct bin_attribute eeprom_attr = { 118 .attr = { 119 .name = "eeprom", 120 .mode = S_IRUGO, 121 }, 122 .size = EEPROM_SIZE, 123 .read = eeprom_read, 124 }; 125 126 /* Return 0 if detection is successful, -ENODEV otherwise */ 127 static int eeprom_detect(struct i2c_client *client, struct i2c_board_info *info) 128 { 129 struct i2c_adapter *adapter = client->adapter; 130 131 /* EDID EEPROMs are often 24C00 EEPROMs, which answer to all 132 addresses 0x50-0x57, but we only care about 0x50. So decline 133 attaching to addresses >= 0x51 on DDC buses */ 134 if (!(adapter->class & I2C_CLASS_SPD) && client->addr >= 0x51) 135 return -ENODEV; 136 137 /* There are four ways we can read the EEPROM data: 138 (1) I2C block reads (faster, but unsupported by most adapters) 139 (2) Word reads (128% overhead) 140 (3) Consecutive byte reads (88% overhead, unsafe) 141 (4) Regular byte data reads (265% overhead) 142 The third and fourth methods are not implemented by this driver 143 because all known adapters support one of the first two. */ 144 if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_WORD_DATA) 145 && !i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_I2C_BLOCK)) 146 return -ENODEV; 147 148 strlcpy(info->type, "eeprom", I2C_NAME_SIZE); 149 150 return 0; 151 } 152 153 static int eeprom_probe(struct i2c_client *client, 154 const struct i2c_device_id *id) 155 { 156 struct i2c_adapter *adapter = client->adapter; 157 struct eeprom_data *data; 158 159 data = devm_kzalloc(&client->dev, sizeof(struct eeprom_data), 160 GFP_KERNEL); 161 if (!data) 162 return -ENOMEM; 163 164 memset(data->data, 0xff, EEPROM_SIZE); 165 i2c_set_clientdata(client, data); 166 mutex_init(&data->update_lock); 167 data->nature = UNKNOWN; 168 169 /* Detect the Vaio nature of EEPROMs. 170 We use the "PCG-" or "VGN-" prefix as the signature. */ 171 if (client->addr == 0x57 172 && i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_BYTE_DATA)) { 173 char name[4]; 174 175 name[0] = i2c_smbus_read_byte_data(client, 0x80); 176 name[1] = i2c_smbus_read_byte_data(client, 0x81); 177 name[2] = i2c_smbus_read_byte_data(client, 0x82); 178 name[3] = i2c_smbus_read_byte_data(client, 0x83); 179 180 if (!memcmp(name, "PCG-", 4) || !memcmp(name, "VGN-", 4)) { 181 dev_info(&client->dev, "Vaio EEPROM detected, " 182 "enabling privacy protection\n"); 183 data->nature = VAIO; 184 } 185 } 186 187 /* create the sysfs eeprom file */ 188 return sysfs_create_bin_file(&client->dev.kobj, &eeprom_attr); 189 } 190 191 static int eeprom_remove(struct i2c_client *client) 192 { 193 sysfs_remove_bin_file(&client->dev.kobj, &eeprom_attr); 194 195 return 0; 196 } 197 198 static const struct i2c_device_id eeprom_id[] = { 199 { "eeprom", 0 }, 200 { } 201 }; 202 203 static struct i2c_driver eeprom_driver = { 204 .driver = { 205 .name = "eeprom", 206 }, 207 .probe = eeprom_probe, 208 .remove = eeprom_remove, 209 .id_table = eeprom_id, 210 211 .class = I2C_CLASS_DDC | I2C_CLASS_SPD, 212 .detect = eeprom_detect, 213 .address_list = normal_i2c, 214 }; 215 216 module_i2c_driver(eeprom_driver); 217 218 MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl> and " 219 "Philip Edelbrock <phil@netroedge.com> and " 220 "Greg Kroah-Hartman <greg@kroah.com>"); 221 MODULE_DESCRIPTION("I2C EEPROM driver"); 222 MODULE_LICENSE("GPL"); 223