drivers/i2c/chips/eeprom.c

   1 /*
   2     eeprom.c - Part of lm_sensors, Linux kernel modules for hardware
   3                monitoring
   4     Copyright (C) 1998, 1999  Frodo Looijaard <frodol@dds.nl> and
   5                                Philip Edelbrock <phil@netroedge.com>
   6     Copyright (C) 2003 Greg Kroah-Hartman <greg@kroah.com>
   7     Copyright (C) 2003 IBM Corp.
   8
   9     2004-01-16  Jean Delvare <khali@linux-fr.org>
  10     Divide the eeprom in 32-byte (arbitrary) slices. This significantly
  11     speeds sensors up, as well as various scripts using the eeprom
  12     module.
  13
  14     This program is free software; you can redistribute it and/or modify
  15     it under the terms of the GNU General Public License as published by
  16     the Free Software Foundation; either version 2 of the License, or
  17     (at your option) any later version.
  18
  19     This program is distributed in the hope that it will be useful,
  20     but WITHOUT ANY WARRANTY; without even the implied warranty of
  21     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22     GNU General Public License for more details.
  23
  24     You should have received a copy of the GNU General Public License
  25     along with this program; if not, write to the Free Software
  26     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  27 */
  28
  29 #include <linux/kernel.h>
  30 #include <linux/init.h>
  31 #include <linux/module.h>
  32 #include <linux/slab.h>
  33 #include <linux/sched.h>
  34 #include <linux/jiffies.h>
  35 #include <linux/i2c.h>
  36 #include <linux/mutex.h>
  37
  38 /* Addresses to scan */
  39 static unsigned short normal_i2c[] = { 0x50, 0x51, 0x52, 0x53, 0x54,
  40                                         0x55, 0x56, 0x57, I2C_CLIENT_END };
  41
  42 /* Insmod parameters */
  43 I2C_CLIENT_INSMOD_1(eeprom);
  44
  45
  46 /* Size of EEPROM in bytes */
  47 #define EEPROM_SIZE             256
  48
  49 /* possible types of eeprom devices */
  50 enum eeprom_nature {
  51         UNKNOWN,
  52         VAIO,
  53 };
  54
  55 /* Each client has this additional data */
  56 struct eeprom_data {
  57         struct i2c_client client;
  58         struct mutex update_lock;
  59         u8 valid;                       /* bitfield, bit!=0 if slice is valid */
  60         unsigned long last_updated[8];  /* In jiffies, 8 slices */
  61         u8 data[EEPROM_SIZE];           /* Register values */
  62         enum eeprom_nature nature;
  63 };
  64
  65
  66 static int eeprom_attach_adapter(struct i2c_adapter *adapter);
  67 static int eeprom_detect(struct i2c_adapter *adapter, int address, int kind);
  68 static int eeprom_detach_client(struct i2c_client *client);
  69
  70 /* This is the driver that will be inserted */
  71 static struct i2c_driver eeprom_driver = {
  72         .driver = {
  73                 .name   = "eeprom",
  74         },
  75         .id             = I2C_DRIVERID_EEPROM,
  76         .attach_adapter = eeprom_attach_adapter,
  77         .detach_client  = eeprom_detach_client,
  78 };
  79
  80 static void eeprom_update_client(struct i2c_client *client, u8 slice)
  81 {
  82         struct eeprom_data *data = i2c_get_clientdata(client);
  83         int i, j;
  84
  85         mutex_lock(&data->update_lock);
  86
  87         if (!(data->valid & (1 << slice)) ||
  88             time_after(jiffies, data->last_updated[slice] + 300 * HZ)) {
  89                 dev_dbg(&client->dev, "Starting eeprom update, slice %u\n", slice);
  90
  91                 if (i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_READ_I2C_BLOCK)) {
  92                         for (i = slice << 5; i < (slice + 1) << 5; i += I2C_SMBUS_BLOCK_MAX)
  93                                 if (i2c_smbus_read_i2c_block_data(client, i, data->data + i) != I2C_SMBUS_BLOCK_MAX)
  94                                         goto exit;
  95                 } else {
  96                         if (i2c_smbus_write_byte(client, slice << 5)) {
  97                                 dev_dbg(&client->dev, "eeprom read start has failed!\n");
  98                                 goto exit;
  99                         }
 100                         for (i = slice << 5; i < (slice + 1) << 5; i++) {
 101                                 j = i2c_smbus_read_byte(client);
 102                                 if (j < 0)
 103                                         goto exit;
 104                                 data->data[i] = (u8) j;
 105                         }
 106                 }
 107                 data->last_updated[slice] = jiffies;
 108                 data->valid |= (1 << slice);
 109         }
 110 exit:
 111         mutex_unlock(&data->update_lock);
 112 }
 113
 114 static ssize_t eeprom_read(struct kobject *kobj, char *buf, loff_t off, size_t count)
 115 {
 116         struct i2c_client *client = to_i2c_client(container_of(kobj, struct device, kobj));
 117         struct eeprom_data *data = i2c_get_clientdata(client);
 118         u8 slice;
 119
 120         if (off > EEPROM_SIZE)
 121                 return 0;
 122         if (off + count > EEPROM_SIZE)
 123                 count = EEPROM_SIZE - off;
 124
 125         /* Only refresh slices which contain requested bytes */
 126         for (slice = off >> 5; slice <= (off + count - 1) >> 5; slice++)
 127                 eeprom_update_client(client, slice);
 128
 129         /* Hide Vaio security settings to regular users (16 first bytes) */
 130         if (data->nature == VAIO && off < 16 && !capable(CAP_SYS_ADMIN)) {
 131                 size_t in_row1 = 16 - off;
 132                 in_row1 = min(in_row1, count);
 133                 memset(buf, 0, in_row1);
 134                 if (count - in_row1 > 0)
 135                         memcpy(buf + in_row1, &data->data[16], count - in_row1);
 136         } else {
 137                 memcpy(buf, &data->data[off], count);
 138         }
 139
 140         return count;
 141 }
 142
 143 static struct bin_attribute eeprom_attr = {
 144         .attr = {
 145                 .name = "eeprom",
 146                 .mode = S_IRUGO,
 147                 .owner = THIS_MODULE,
 148         },
 149         .size = EEPROM_SIZE,
 150         .read = eeprom_read,
 151 };
 152
 153 static int eeprom_attach_adapter(struct i2c_adapter *adapter)
 154 {
 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 *new_client;
 162         struct eeprom_data *data;
 163         int err = 0;
 164
 165         /* There are three ways we can read the EEPROM data:
 166            (1) I2C block reads (faster, but unsupported by most adapters)
 167            (2) Consecutive byte reads (100% overhead)
 168            (3) Regular byte data reads (200% overhead)
 169            The third method is not implemented by this driver because all
 170            known adapters support at least the second. */
 171         if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_BYTE_DATA
 172                                             | I2C_FUNC_SMBUS_BYTE))
 173                 goto exit;
 174
 175         if (!(data = kzalloc(sizeof(struct eeprom_data), GFP_KERNEL))) {
 176                 err = -ENOMEM;
 177                 goto exit;
 178         }
 179
 180         new_client = &data->client;
 181         memset(data->data, 0xff, EEPROM_SIZE);
 182         i2c_set_clientdata(new_client, data);
 183         new_client->addr = address;
 184         new_client->adapter = adapter;
 185         new_client->driver = &eeprom_driver;
 186         new_client->flags = 0;
 187
 188         /* Fill in the remaining client fields */
 189         strlcpy(new_client->name, "eeprom", I2C_NAME_SIZE);
 190         data->valid = 0;
 191         mutex_init(&data->update_lock);
 192         data->nature = UNKNOWN;
 193
 194         /* Tell the I2C layer a new client has arrived */
 195         if ((err = i2c_attach_client(new_client)))
 196                 goto exit_kfree;
 197
 198         /* Detect the Vaio nature of EEPROMs.
 199            We use the "PCG-" prefix as the signature. */
 200         if (address == 0x57) {
 201                 if (i2c_smbus_read_byte_data(new_client, 0x80) == 'P'
 202                  && i2c_smbus_read_byte(new_client) == 'C'
 203                  && i2c_smbus_read_byte(new_client) == 'G'
 204                  && i2c_smbus_read_byte(new_client) == '-') {
 205                         dev_info(&new_client->dev, "Vaio EEPROM detected, "
 206                                 "enabling password protection\n");
 207                         data->nature = VAIO;
 208                 }
 209         }
 210
 211         /* create the sysfs eeprom file */
 212         sysfs_create_bin_file(&new_client->dev.kobj, &eeprom_attr);
 213
 214         return 0;
 215
 216 exit_kfree:
 217         kfree(data);
 218 exit:
 219         return err;
 220 }
 221
 222 static int eeprom_detach_client(struct i2c_client *client)
 223 {
 224         int err;
 225
 226         err = i2c_detach_client(client);
 227         if (err)
 228                 return err;
 229
 230         kfree(i2c_get_clientdata(client));
 231
 232         return 0;
 233 }
 234
 235 static int __init eeprom_init(void)
 236 {
 237         return i2c_add_driver(&eeprom_driver);
 238 }
 239
 240 static void __exit eeprom_exit(void)
 241 {
 242         i2c_del_driver(&eeprom_driver);
 243 }
 244
 245
 246 MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl> and "
 247                 "Philip Edelbrock <phil@netroedge.com> and "
 248                 "Greg Kroah-Hartman <greg@kroah.com>");
 249 MODULE_DESCRIPTION("I2C EEPROM driver");
 250 MODULE_LICENSE("GPL");
 251
 252 module_init(eeprom_init);
 253 module_exit(eeprom_exit);