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