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/jiffies.h> 23 #include <linux/i2c.h> 24 #include <linux/mutex.h> 25 26 /* Addresses to scan */ 27 static const unsigned short normal_i2c[] = { 0x50, 0x51, 0x52, 0x53, 0x54, 28 0x55, 0x56, 0x57, I2C_CLIENT_END }; 29 30 31 /* Size of EEPROM in bytes */ 32 #define EEPROM_SIZE 256 33 34 /* possible types of eeprom devices */ 35 enum eeprom_nature { 36 UNKNOWN, 37 VAIO, 38 }; 39 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; 47 }; 48 49 50 static void eeprom_update_client(struct i2c_client *client, u8 slice) 51 { 52 struct eeprom_data *data = i2c_get_clientdata(client); 53 int i; 54 55 mutex_lock(&data->update_lock); 56 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); 60 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; 74 } 75 } 76 data->last_updated[slice] = jiffies; 77 data->valid |= (1 << slice); 78 } 79 exit: 80 mutex_unlock(&data->update_lock); 81 } 82 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) 86 { 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; 90 91 if (off > EEPROM_SIZE) 92 return 0; 93 if (off + count > EEPROM_SIZE) 94 count = EEPROM_SIZE - off; 95 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); 99 100 /* 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; 106 107 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]; 113 } 114 } else { 115 memcpy(buf, &data->data[off], count); 116 } 117 118 return count; 119 } 120 121 static struct bin_attribute eeprom_attr = { 122 .attr = { 123 .name = "eeprom", 124 .mode = S_IRUGO, 125 }, 126 .size = EEPROM_SIZE, 127 .read = eeprom_read, 128 }; 129 130 /* Return 0 if detection is successful, -ENODEV otherwise */ 131 static int eeprom_detect(struct i2c_client *client, struct i2c_board_info *info) 132 { 133 struct i2c_adapter *adapter = client->adapter; 134 135 /* 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; 140 141 /* 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; 151 152 strlcpy(info->type, "eeprom", I2C_NAME_SIZE); 153 154 return 0; 155 } 156 157 static int eeprom_probe(struct i2c_client *client, 158 const struct i2c_device_id *id) 159 { 160 struct i2c_adapter *adapter = client->adapter; 161 struct eeprom_data *data; 162 163 data = devm_kzalloc(&client->dev, sizeof(struct eeprom_data), 164 GFP_KERNEL); 165 if (!data) 166 return -ENOMEM; 167 168 memset(data->data, 0xff, EEPROM_SIZE); 169 i2c_set_clientdata(client, data); 170 mutex_init(&data->update_lock); 171 data->nature = UNKNOWN; 172 173 /* 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]; 178 179 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); 183 184 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; 188 } 189 } 190 191 /* create the sysfs eeprom file */ 192 return sysfs_create_bin_file(&client->dev.kobj, &eeprom_attr); 193 } 194 195 static int eeprom_remove(struct i2c_client *client) 196 { 197 sysfs_remove_bin_file(&client->dev.kobj, &eeprom_attr); 198 199 return 0; 200 } 201 202 static const struct i2c_device_id eeprom_id[] = { 203 { "eeprom", 0 }, 204 { } 205 }; 206 207 static struct i2c_driver eeprom_driver = { 208 .driver = { 209 .name = "eeprom", 210 }, 211 .probe = eeprom_probe, 212 .remove = eeprom_remove, 213 .id_table = eeprom_id, 214 215 .class = I2C_CLASS_DDC | I2C_CLASS_SPD, 216 .detect = eeprom_detect, 217 .address_list = normal_i2c, 218 }; 219 220 module_i2c_driver(eeprom_driver); 221 222 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"); 227