drivers/i2c/chips/eeprom.c

   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     You should have received a copy of the GNU General Public License
  19     along with this program; if not, write to the Free Software
  20     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  21 */
  22
  23 #include <linux/kernel.h>
  24 #include <linux/init.h>
  25 #include <linux/module.h>
  26 #include <linux/slab.h>
  27 #include <linux/jiffies.h>
  28 #include <linux/i2c.h>
  29 #include <linux/mutex.h>
  30
  31 /* Addresses to scan */
  32 static const unsigned short normal_i2c[] = { 0x50, 0x51, 0x52, 0x53, 0x54,
  33                                         0x55, 0x56, 0x57, I2C_CLIENT_END };
  34
  35 /* Insmod parameters */
  36 I2C_CLIENT_INSMOD_1(eeprom);
  37
  38
  39 /* Size of EEPROM in bytes */
  40 #define EEPROM_SIZE             256
  41
  42 /* possible types of eeprom devices */
  43 enum eeprom_nature {
  44         UNKNOWN,
  45         VAIO,
  46 };
  47
  48 /* Each client has this additional data */
  49 struct eeprom_data {
  50         struct i2c_client client;
  51         struct mutex update_lock;
  52         u8 valid;                       /* bitfield, bit!=0 if slice is valid */
  53         unsigned long last_updated[8];  /* In jiffies, 8 slices */
  54         u8 data[EEPROM_SIZE];           /* Register values */
  55         enum eeprom_nature nature;
  56 };
  57
  58
  59 static int eeprom_attach_adapter(struct i2c_adapter *adapter);
  60 static int eeprom_detect(struct i2c_adapter *adapter, int address, int kind);
  61 static int eeprom_detach_client(struct i2c_client *client);
  62
  63 /* This is the driver that will be inserted */
  64 static struct i2c_driver eeprom_driver = {
  65         .driver = {
  66                 .name   = "eeprom",
  67         },
  68         .attach_adapter = eeprom_attach_adapter,
  69         .detach_client  = eeprom_detach_client,
  70 };
  71
  72 static void eeprom_update_client(struct i2c_client *client, u8 slice)
  73 {
  74         struct eeprom_data *data = i2c_get_clientdata(client);
  75         int i;
  76
  77         mutex_lock(&data->update_lock);
  78
  79         if (!(data->valid & (1 << slice)) ||
  80             time_after(jiffies, data->last_updated[slice] + 300 * HZ)) {
  81                 dev_dbg(&client->dev, "Starting eeprom update, slice %u\n", slice);
  82
  83                 if (i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_READ_I2C_BLOCK)) {
  84                         for (i = slice << 5; i < (slice + 1) << 5; i += 32)
  85                                 if (i2c_smbus_read_i2c_block_data(client, i,
  86                                                         32, data->data + i)
  87                                                         != 32)
  88                                         goto exit;
  89                 } else {
  90                         for (i = slice << 5; i < (slice + 1) << 5; i += 2) {
  91                                 int word = i2c_smbus_read_word_data(client, i);
  92                                 if (word < 0)
  93                                         goto exit;
  94                                 data->data[i] = word & 0xff;
  95                                 data->data[i + 1] = word >> 8;
  96                         }
  97                 }
  98                 data->last_updated[slice] = jiffies;
  99                 data->valid |= (1 << slice);
 100         }
 101 exit:
 102         mutex_unlock(&data->update_lock);
 103 }
 104
 105 static ssize_t eeprom_read(struct kobject *kobj, struct bin_attribute *bin_attr,
 106                            char *buf, loff_t off, size_t count)
 107 {
 108         struct i2c_client *client = to_i2c_client(container_of(kobj, struct device, kobj));
 109         struct eeprom_data *data = i2c_get_clientdata(client);
 110         u8 slice;
 111
 112         if (off > EEPROM_SIZE)
 113                 return 0;
 114         if (off + count > EEPROM_SIZE)
 115                 count = EEPROM_SIZE - off;
 116
 117         /* Only refresh slices which contain requested bytes */
 118         for (slice = off >> 5; slice <= (off + count - 1) >> 5; slice++)
 119                 eeprom_update_client(client, slice);
 120
 121         /* Hide Vaio private settings to regular users:
 122            - BIOS passwords: bytes 0x00 to 0x0f
 123            - UUID: bytes 0x10 to 0x1f
 124            - Serial number: 0xc0 to 0xdf */
 125         if (data->nature == VAIO && !capable(CAP_SYS_ADMIN)) {
 126                 int i;
 127
 128                 for (i = 0; i < count; i++) {
 129                         if ((off + i <= 0x1f) ||
 130                             (off + i >= 0xc0 && off + i <= 0xdf))
 131                                 buf[i] = 0;
 132                         else
 133                                 buf[i] = data->data[off + i];
 134                 }
 135         } else {
 136                 memcpy(buf, &data->data[off], count);
 137         }
 138
 139         return count;
 140 }
 141
 142 static struct bin_attribute eeprom_attr = {
 143         .attr = {
 144                 .name = "eeprom",
 145                 .mode = S_IRUGO,
 146         },
 147         .size = EEPROM_SIZE,
 148         .read = eeprom_read,
 149 };
 150
 151 static int eeprom_attach_adapter(struct i2c_adapter *adapter)
 152 {
 153         if (!(adapter->class & (I2C_CLASS_DDC | I2C_CLASS_SPD)))
 154                 return 0;
 155         return i2c_probe(adapter, &addr_data, eeprom_detect);
 156 }
 157
 158 /* This function is called by i2c_probe */
 159 static int eeprom_detect(struct i2c_adapter *adapter, int address, int kind)
 160 {
 161         struct i2c_client *client;
 162         struct eeprom_data *data;
 163         int err = 0;
 164
 165         /* EDID EEPROMs are often 24C00 EEPROMs, which answer to all
 166            addresses 0x50-0x57, but we only care about 0x50. So decline
 167            attaching to addresses >= 0x51 on DDC buses */
 168         if (!(adapter->class & I2C_CLASS_SPD) && address >= 0x51)
 169                 goto exit;
 170
 171         /* There are four ways we can read the EEPROM data:
 172            (1) I2C block reads (faster, but unsupported by most adapters)
 173            (2) Word reads (128% overhead)
 174            (3) Consecutive byte reads (88% overhead, unsafe)
 175            (4) Regular byte data reads (265% overhead)
 176            The third and fourth methods are not implemented by this driver
 177            because all known adapters support one of the first two. */
 178         if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_WORD_DATA)
 179          && !i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_I2C_BLOCK))
 180                 goto exit;
 181
 182         if (!(data = kzalloc(sizeof(struct eeprom_data), GFP_KERNEL))) {
 183                 err = -ENOMEM;
 184                 goto exit;
 185         }
 186
 187         client = &data->client;
 188         memset(data->data, 0xff, EEPROM_SIZE);
 189         i2c_set_clientdata(client, data);
 190         client->addr = address;
 191         client->adapter = adapter;
 192         client->driver = &eeprom_driver;
 193
 194         /* Fill in the remaining client fields */
 195         strlcpy(client->name, "eeprom", I2C_NAME_SIZE);
 196         mutex_init(&data->update_lock);
 197         data->nature = UNKNOWN;
 198
 199         /* Tell the I2C layer a new client has arrived */
 200         if ((err = i2c_attach_client(client)))
 201                 goto exit_kfree;
 202
 203         /* Detect the Vaio nature of EEPROMs.
 204            We use the "PCG-" or "VGN-" prefix as the signature. */
 205         if (address == 0x57
 206          && i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_BYTE_DATA)) {
 207                 char name[4];
 208
 209                 name[0] = i2c_smbus_read_byte_data(client, 0x80);
 210                 name[1] = i2c_smbus_read_byte_data(client, 0x81);
 211                 name[2] = i2c_smbus_read_byte_data(client, 0x82);
 212                 name[3] = i2c_smbus_read_byte_data(client, 0x83);
 213
 214                 if (!memcmp(name, "PCG-", 4) || !memcmp(name, "VGN-", 4)) {
 215                         dev_info(&client->dev, "Vaio EEPROM detected, "
 216                                  "enabling privacy protection\n");
 217                         data->nature = VAIO;
 218                 }
 219         }
 220
 221         /* create the sysfs eeprom file */
 222         err = sysfs_create_bin_file(&client->dev.kobj, &eeprom_attr);
 223         if (err)
 224                 goto exit_detach;
 225
 226         return 0;
 227
 228 exit_detach:
 229         i2c_detach_client(client);
 230 exit_kfree:
 231         kfree(data);
 232 exit:
 233         return err;
 234 }
 235
 236 static int eeprom_detach_client(struct i2c_client *client)
 237 {
 238         int err;
 239
 240         sysfs_remove_bin_file(&client->dev.kobj, &eeprom_attr);
 241
 242         err = i2c_detach_client(client);
 243         if (err)
 244                 return err;
 245
 246         kfree(i2c_get_clientdata(client));
 247
 248         return 0;
 249 }
 250
 251 static int __init eeprom_init(void)
 252 {
 253         return i2c_add_driver(&eeprom_driver);
 254 }
 255
 256 static void __exit eeprom_exit(void)
 257 {
 258         i2c_del_driver(&eeprom_driver);
 259 }
 260
 261
 262 MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl> and "
 263                 "Philip Edelbrock <phil@netroedge.com> and "
 264                 "Greg Kroah-Hartman <greg@kroah.com>");
 265 MODULE_DESCRIPTION("I2C EEPROM driver");
 266 MODULE_LICENSE("GPL");
 267
 268 module_init(eeprom_init);
 269 module_exit(eeprom_exit);