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/config.h>
  30 #include <linux/kernel.h>
  31 #include <linux/init.h>
  32 #include <linux/module.h>
  33 #include <linux/slab.h>
  34 #include <linux/sched.h>
  35 #include <linux/jiffies.h>
  36 #include <linux/i2c.h>
  37 #include <linux/i2c-sensor.h>
  38
  39 /* Addresses to scan */
  40 static unsigned short normal_i2c[] = { 0x50, 0x51, 0x52, 0x53, 0x54,
  41                                         0x55, 0x56, 0x57, I2C_CLIENT_END };
  42 static unsigned int normal_isa[] = { I2C_CLIENT_ISA_END };
  43
  44 /* Insmod parameters */
  45 SENSORS_INSMOD_1(eeprom);
  46
  47
  48 /* Size of EEPROM in bytes */
  49 #define EEPROM_SIZE             256
  50
  51 /* possible types of eeprom devices */
  52 enum eeprom_nature {
  53         UNKNOWN,
  54         VAIO,
  55 };
  56
  57 /* Each client has this additional data */
  58 struct eeprom_data {
  59         struct i2c_client client;
  60         struct semaphore update_lock;
  61         u8 valid;                       /* bitfield, bit!=0 if slice is valid */
  62         unsigned long last_updated[8];  /* In jiffies, 8 slices */
  63         u8 data[EEPROM_SIZE];           /* Register values */
  64         enum eeprom_nature nature;
  65 };
  66
  67
  68 static int eeprom_attach_adapter(struct i2c_adapter *adapter);
  69 static int eeprom_detect(struct i2c_adapter *adapter, int address, int kind);
  70 static int eeprom_detach_client(struct i2c_client *client);
  71
  72 /* This is the driver that will be inserted */
  73 static struct i2c_driver eeprom_driver = {
  74         .owner          = THIS_MODULE,
  75         .name           = "eeprom",
  76         .id             = I2C_DRIVERID_EEPROM,
  77         .flags          = I2C_DF_NOTIFY,
  78         .attach_adapter = eeprom_attach_adapter,
  79         .detach_client  = eeprom_detach_client,
  80 };
  81
  82 static void eeprom_update_client(struct i2c_client *client, u8 slice)
  83 {
  84         struct eeprom_data *data = i2c_get_clientdata(client);
  85         int i, j;
  86
  87         down(&data->update_lock);
  88
  89         if (!(data->valid & (1 << slice)) ||
  90             time_after(jiffies, data->last_updated[slice] + 300 * HZ)) {
  91                 dev_dbg(&client->dev, "Starting eeprom update, slice %u\n", slice);
  92
  93                 if (i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_READ_I2C_BLOCK)) {
  94                         for (i = slice << 5; i < (slice + 1) << 5; i += I2C_SMBUS_I2C_BLOCK_MAX)
  95                                 if (i2c_smbus_read_i2c_block_data(client, i, data->data + i) != I2C_SMBUS_I2C_BLOCK_MAX)
  96                                         goto exit;
  97                 } else {
  98                         if (i2c_smbus_write_byte(client, slice << 5)) {
  99                                 dev_dbg(&client->dev, "eeprom read start has failed!\n");
 100                                 goto exit;
 101                         }
 102                         for (i = slice << 5; i < (slice + 1) << 5; i++) {
 103                                 j = i2c_smbus_read_byte(client);
 104                                 if (j < 0)
 105                                         goto exit;
 106                                 data->data[i] = (u8) j;
 107                         }
 108                 }
 109                 data->last_updated[slice] = jiffies;
 110                 data->valid |= (1 << slice);
 111         }
 112 exit:
 113         up(&data->update_lock);
 114 }
 115
 116 static ssize_t eeprom_read(struct kobject *kobj, char *buf, loff_t off, size_t count)
 117 {
 118         struct i2c_client *client = to_i2c_client(container_of(kobj, struct device, kobj));
 119         struct eeprom_data *data = i2c_get_clientdata(client);
 120         u8 slice;
 121
 122         if (off > EEPROM_SIZE)
 123                 return 0;
 124         if (off + count > EEPROM_SIZE)
 125                 count = EEPROM_SIZE - off;
 126
 127         /* Only refresh slices which contain requested bytes */
 128         for (slice = off >> 5; slice <= (off + count - 1) >> 5; slice++)
 129                 eeprom_update_client(client, slice);
 130
 131         /* Hide Vaio security settings to regular users (16 first bytes) */
 132         if (data->nature == VAIO && off < 16 && !capable(CAP_SYS_ADMIN)) {
 133                 size_t in_row1 = 16 - off;
 134                 in_row1 = min(in_row1, count);
 135                 memset(buf, 0, in_row1);
 136                 if (count - in_row1 > 0)
 137                         memcpy(buf + in_row1, &data->data[16], count - in_row1);
 138         } else {
 139                 memcpy(buf, &data->data[off], count);
 140         }
 141
 142         return count;
 143 }
 144
 145 static struct bin_attribute eeprom_attr = {
 146         .attr = {
 147                 .name = "eeprom",
 148                 .mode = S_IRUGO,
 149                 .owner = THIS_MODULE,
 150         },
 151         .size = EEPROM_SIZE,
 152         .read = eeprom_read,
 153 };
 154
 155 static int eeprom_attach_adapter(struct i2c_adapter *adapter)
 156 {
 157         return i2c_detect(adapter, &addr_data, eeprom_detect);
 158 }
 159
 160 /* This function is called by i2c_detect */
 161 int eeprom_detect(struct i2c_adapter *adapter, int address, int kind)
 162 {
 163         struct i2c_client *new_client;
 164         struct eeprom_data *data;
 165         int err = 0;
 166
 167         /* There are three ways we can read the EEPROM data:
 168            (1) I2C block reads (faster, but unsupported by most adapters)
 169            (2) Consecutive byte reads (100% overhead)
 170            (3) Regular byte data reads (200% overhead)
 171            The third method is not implemented by this driver because all
 172            known adapters support at least the second. */
 173         if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_BYTE_DATA
 174                                             | I2C_FUNC_SMBUS_BYTE))
 175                 goto exit;
 176
 177         /* OK. For now, we presume we have a valid client. We now create the
 178            client structure, even though we cannot fill it completely yet.
 179            But it allows us to access eeprom_{read,write}_value. */
 180         if (!(data = kmalloc(sizeof(struct eeprom_data), GFP_KERNEL))) {
 181                 err = -ENOMEM;
 182                 goto exit;
 183         }
 184         memset(data, 0, sizeof(struct eeprom_data));
 185
 186         new_client = &data->client;
 187         memset(data->data, 0xff, EEPROM_SIZE);
 188         i2c_set_clientdata(new_client, data);
 189         new_client->addr = address;
 190         new_client->adapter = adapter;
 191         new_client->driver = &eeprom_driver;
 192         new_client->flags = 0;
 193
 194         /* prevent 24RF08 corruption */
 195         i2c_smbus_write_quick(new_client, 0);
 196
 197         /* Fill in the remaining client fields */
 198         strlcpy(new_client->name, "eeprom", I2C_NAME_SIZE);
 199         data->valid = 0;
 200         init_MUTEX(&data->update_lock);
 201         data->nature = UNKNOWN;
 202
 203         /* Tell the I2C layer a new client has arrived */
 204         if ((err = i2c_attach_client(new_client)))
 205                 goto exit_kfree;
 206
 207         /* Detect the Vaio nature of EEPROMs.
 208            We use the "PCG-" prefix as the signature. */
 209         if (address == 0x57) {
 210                 if (i2c_smbus_read_byte_data(new_client, 0x80) == 'P'
 211                  && i2c_smbus_read_byte(new_client) == 'C'
 212                  && i2c_smbus_read_byte(new_client) == 'G'
 213                  && i2c_smbus_read_byte(new_client) == '-') {
 214                         dev_info(&new_client->dev, "Vaio EEPROM detected, "
 215                                 "enabling password protection\n");
 216                         data->nature = VAIO;
 217                 }
 218         }
 219
 220         /* create the sysfs eeprom file */
 221         sysfs_create_bin_file(&new_client->dev.kobj, &eeprom_attr);
 222
 223         return 0;
 224
 225 exit_kfree:
 226         kfree(data);
 227 exit:
 228         return err;
 229 }
 230
 231 static int eeprom_detach_client(struct i2c_client *client)
 232 {
 233         int err;
 234
 235         err = i2c_detach_client(client);
 236         if (err) {
 237                 dev_err(&client->dev, "Client deregistration failed, client not detached.\n");
 238                 return err;
 239         }
 240
 241         kfree(i2c_get_clientdata(client));
 242
 243         return 0;
 244 }
 245
 246 static int __init eeprom_init(void)
 247 {
 248         return i2c_add_driver(&eeprom_driver);
 249 }
 250
 251 static void __exit eeprom_exit(void)
 252 {
 253         i2c_del_driver(&eeprom_driver);
 254 }
 255
 256
 257 MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl> and "
 258                 "Philip Edelbrock <phil@netroedge.com> and "
 259                 "Greg Kroah-Hartman <greg@kroah.com>");
 260 MODULE_DESCRIPTION("I2C EEPROM driver");
 261 MODULE_LICENSE("GPL");
 262
 263 module_init(eeprom_init);
 264 module_exit(eeprom_exit);