1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Copyright (C) 1998, 1999 Frodo Looijaard <frodol@dds.nl> and 4 * Philip Edelbrock <phil@netroedge.com> 5 * Copyright (C) 2003 Greg Kroah-Hartman <greg@kroah.com> 6 * Copyright (C) 2003 IBM Corp. 7 * Copyright (C) 2004 Jean Delvare <jdelvare@suse.de> 8 */ 9 10 #include <linux/kernel.h> 11 #include <linux/module.h> 12 #include <linux/device.h> 13 #include <linux/capability.h> 14 #include <linux/jiffies.h> 15 #include <linux/i2c.h> 16 #include <linux/mutex.h> 17 18 /* Addresses to scan */ 19 static const unsigned short normal_i2c[] = { 0x50, 0x51, 0x52, 0x53, 0x54, 20 0x55, 0x56, 0x57, I2C_CLIENT_END }; 21 22 23 /* Size of EEPROM in bytes */ 24 #define EEPROM_SIZE 256 25 26 /* possible types of eeprom devices */ 27 enum eeprom_nature { 28 UNKNOWN, 29 VAIO, 30 }; 31 32 /* Each client has this additional data */ 33 struct eeprom_data { 34 struct mutex update_lock; 35 u8 valid; /* bitfield, bit!=0 if slice is valid */ 36 unsigned long last_updated[8]; /* In jiffies, 8 slices */ 37 u8 data[EEPROM_SIZE]; /* Register values */ 38 enum eeprom_nature nature; 39 }; 40 41 42 static void eeprom_update_client(struct i2c_client *client, u8 slice) 43 { 44 struct eeprom_data *data = i2c_get_clientdata(client); 45 int i; 46 47 mutex_lock(&data->update_lock); 48 49 if (!(data->valid & (1 << slice)) || 50 time_after(jiffies, data->last_updated[slice] + 300 * HZ)) { 51 dev_dbg(&client->dev, "Starting eeprom update, slice %u\n", slice); 52 53 if (i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_READ_I2C_BLOCK)) { 54 for (i = slice << 5; i < (slice + 1) << 5; i += 32) 55 if (i2c_smbus_read_i2c_block_data(client, i, 56 32, data->data + i) 57 != 32) 58 goto exit; 59 } else { 60 for (i = slice << 5; i < (slice + 1) << 5; i += 2) { 61 int word = i2c_smbus_read_word_data(client, i); 62 if (word < 0) 63 goto exit; 64 data->data[i] = word & 0xff; 65 data->data[i + 1] = word >> 8; 66 } 67 } 68 data->last_updated[slice] = jiffies; 69 data->valid |= (1 << slice); 70 } 71 exit: 72 mutex_unlock(&data->update_lock); 73 } 74 75 static ssize_t eeprom_read(struct file *filp, struct kobject *kobj, 76 struct bin_attribute *bin_attr, 77 char *buf, loff_t off, size_t count) 78 { 79 struct i2c_client *client = kobj_to_i2c_client(kobj); 80 struct eeprom_data *data = i2c_get_clientdata(client); 81 u8 slice; 82 83 /* Only refresh slices which contain requested bytes */ 84 for (slice = off >> 5; slice <= (off + count - 1) >> 5; slice++) 85 eeprom_update_client(client, slice); 86 87 /* Hide Vaio private settings to regular users: 88 - BIOS passwords: bytes 0x00 to 0x0f 89 - UUID: bytes 0x10 to 0x1f 90 - Serial number: 0xc0 to 0xdf */ 91 if (data->nature == VAIO && !capable(CAP_SYS_ADMIN)) { 92 int i; 93 94 for (i = 0; i < count; i++) { 95 if ((off + i <= 0x1f) || 96 (off + i >= 0xc0 && off + i <= 0xdf)) 97 buf[i] = 0; 98 else 99 buf[i] = data->data[off + i]; 100 } 101 } else { 102 memcpy(buf, &data->data[off], count); 103 } 104 105 return count; 106 } 107 108 static const struct bin_attribute eeprom_attr = { 109 .attr = { 110 .name = "eeprom", 111 .mode = S_IRUGO, 112 }, 113 .size = EEPROM_SIZE, 114 .read = eeprom_read, 115 }; 116 117 /* Return 0 if detection is successful, -ENODEV otherwise */ 118 static int eeprom_detect(struct i2c_client *client, struct i2c_board_info *info) 119 { 120 struct i2c_adapter *adapter = client->adapter; 121 122 /* EDID EEPROMs are often 24C00 EEPROMs, which answer to all 123 addresses 0x50-0x57, but we only care about 0x50. So decline 124 attaching to addresses >= 0x51 on DDC buses */ 125 if (!(adapter->class & I2C_CLASS_SPD) && client->addr >= 0x51) 126 return -ENODEV; 127 128 /* There are four ways we can read the EEPROM data: 129 (1) I2C block reads (faster, but unsupported by most adapters) 130 (2) Word reads (128% overhead) 131 (3) Consecutive byte reads (88% overhead, unsafe) 132 (4) Regular byte data reads (265% overhead) 133 The third and fourth methods are not implemented by this driver 134 because all known adapters support one of the first two. */ 135 if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_WORD_DATA) 136 && !i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_I2C_BLOCK)) 137 return -ENODEV; 138 139 strlcpy(info->type, "eeprom", I2C_NAME_SIZE); 140 141 return 0; 142 } 143 144 static int eeprom_probe(struct i2c_client *client, 145 const struct i2c_device_id *id) 146 { 147 struct i2c_adapter *adapter = client->adapter; 148 struct eeprom_data *data; 149 150 data = devm_kzalloc(&client->dev, sizeof(struct eeprom_data), 151 GFP_KERNEL); 152 if (!data) 153 return -ENOMEM; 154 155 memset(data->data, 0xff, EEPROM_SIZE); 156 i2c_set_clientdata(client, data); 157 mutex_init(&data->update_lock); 158 data->nature = UNKNOWN; 159 160 /* Detect the Vaio nature of EEPROMs. 161 We use the "PCG-" or "VGN-" prefix as the signature. */ 162 if (client->addr == 0x57 163 && i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_BYTE_DATA)) { 164 char name[4]; 165 166 name[0] = i2c_smbus_read_byte_data(client, 0x80); 167 name[1] = i2c_smbus_read_byte_data(client, 0x81); 168 name[2] = i2c_smbus_read_byte_data(client, 0x82); 169 name[3] = i2c_smbus_read_byte_data(client, 0x83); 170 171 if (!memcmp(name, "PCG-", 4) || !memcmp(name, "VGN-", 4)) { 172 dev_info(&client->dev, "Vaio EEPROM detected, " 173 "enabling privacy protection\n"); 174 data->nature = VAIO; 175 } 176 } 177 178 /* Let the users know they are using deprecated driver */ 179 dev_notice(&client->dev, 180 "eeprom driver is deprecated, please use at24 instead\n"); 181 182 /* create the sysfs eeprom file */ 183 return sysfs_create_bin_file(&client->dev.kobj, &eeprom_attr); 184 } 185 186 static int eeprom_remove(struct i2c_client *client) 187 { 188 sysfs_remove_bin_file(&client->dev.kobj, &eeprom_attr); 189 190 return 0; 191 } 192 193 static const struct i2c_device_id eeprom_id[] = { 194 { "eeprom", 0 }, 195 { } 196 }; 197 198 static struct i2c_driver eeprom_driver = { 199 .driver = { 200 .name = "eeprom", 201 }, 202 .probe = eeprom_probe, 203 .remove = eeprom_remove, 204 .id_table = eeprom_id, 205 206 .class = I2C_CLASS_DDC | I2C_CLASS_SPD, 207 .detect = eeprom_detect, 208 .address_list = normal_i2c, 209 }; 210 211 module_i2c_driver(eeprom_driver); 212 213 MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl> and " 214 "Philip Edelbrock <phil@netroedge.com> and " 215 "Greg Kroah-Hartman <greg@kroah.com>"); 216 MODULE_DESCRIPTION("I2C EEPROM driver"); 217 MODULE_LICENSE("GPL"); 218