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/i2c-sensor.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 static unsigned int normal_isa[] = { I2C_CLIENT_ISA_END };
  42
  43 /* Insmod parameters */
  44 SENSORS_INSMOD_1(eeprom);
  45
  46
  47 /* Size of EEPROM in bytes */
  48 #define EEPROM_SIZE             256
  49
  50 /* possible types of eeprom devices */
  51 enum eeprom_nature {
  52         UNKNOWN,
  53         VAIO,
  54 };
  55
  56 /* Each client has this additional data */
  57 struct eeprom_data {
  58         struct i2c_client client;
  59         struct semaphore update_lock;
  60         u8 valid;                       /* bitfield, bit!=0 if slice is valid */
  61         unsigned long last_updated[8];  /* In jiffies, 8 slices */
  62         u8 data[EEPROM_SIZE];           /* Register values */
  63         enum eeprom_nature nature;
  64 };
  65
  66
  67 static int eeprom_attach_adapter(struct i2c_adapter *adapter);
  68 static int eeprom_detect(struct i2c_adapter *adapter, int address, int kind);
  69 static int eeprom_detach_client(struct i2c_client *client);
  70
  71 /* This is the driver that will be inserted */
  72 static struct i2c_driver eeprom_driver = {
  73         .owner          = THIS_MODULE,
  74         .name           = "eeprom",
  75         .id             = I2C_DRIVERID_EEPROM,
  76         .flags          = I2C_DF_NOTIFY,
  77         .attach_adapter = eeprom_attach_adapter,
  78         .detach_client  = eeprom_detach_client,
  79 };
  80
  81 static void eeprom_update_client(struct i2c_client *client, u8 slice)
  82 {
  83         struct eeprom_data *data = i2c_get_clientdata(client);
  84         int i, j;
  85
  86         down(&data->update_lock);
  87
  88         if (!(data->valid & (1 << slice)) ||
  89             time_after(jiffies, data->last_updated[slice] + 300 * HZ)) {
  90                 dev_dbg(&client->dev, "Starting eeprom update, slice %u\n", slice);
  91
  92                 if (i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_READ_I2C_BLOCK)) {
  93                         for (i = slice << 5; i < (slice + 1) << 5; i += I2C_SMBUS_I2C_BLOCK_MAX)
  94                                 if (i2c_smbus_read_i2c_block_data(client, i, data->data + i) != I2C_SMBUS_I2C_BLOCK_MAX)
  95                                         goto exit;
  96                 } else {
  97                         if (i2c_smbus_write_byte(client, slice << 5)) {
  98                                 dev_dbg(&client->dev, "eeprom read start has failed!\n");
  99                                 goto exit;
 100                         }
 101                         for (i = slice << 5; i < (slice + 1) << 5; i++) {
 102                                 j = i2c_smbus_read_byte(client);
 103                                 if (j < 0)
 104                                         goto exit;
 105                                 data->data[i] = (u8) j;
 106                         }
 107                 }
 108                 data->last_updated[slice] = jiffies;
 109                 data->valid |= (1 << slice);
 110         }
 111 exit:
 112         up(&data->update_lock);
 113 }
 114
 115 static ssize_t eeprom_read(struct kobject *kobj, char *buf, loff_t off, size_t count)
 116 {
 117         struct i2c_client *client = to_i2c_client(container_of(kobj, struct device, kobj));
 118         struct eeprom_data *data = i2c_get_clientdata(client);
 119         u8 slice;
 120
 121         if (off > EEPROM_SIZE)
 122                 return 0;
 123         if (off + count > EEPROM_SIZE)
 124                 count = EEPROM_SIZE - off;
 125
 126         /* Only refresh slices which contain requested bytes */
 127         for (slice = off >> 5; slice <= (off + count - 1) >> 5; slice++)
 128                 eeprom_update_client(client, slice);
 129
 130         /* Hide Vaio security settings to regular users (16 first bytes) */
 131         if (data->nature == VAIO && off < 16 && !capable(CAP_SYS_ADMIN)) {
 132                 size_t in_row1 = 16 - off;
 133                 in_row1 = min(in_row1, count);
 134                 memset(buf, 0, in_row1);
 135                 if (count - in_row1 > 0)
 136                         memcpy(buf + in_row1, &data->data[16], count - in_row1);
 137         } else {
 138                 memcpy(buf, &data->data[off], count);
 139         }
 140
 141         return count;
 142 }
 143
 144 static struct bin_attribute eeprom_attr = {
 145         .attr = {
 146                 .name = "eeprom",
 147                 .mode = S_IRUGO,
 148                 .owner = THIS_MODULE,
 149         },
 150         .size = EEPROM_SIZE,
 151         .read = eeprom_read,
 152 };
 153
 154 static int eeprom_attach_adapter(struct i2c_adapter *adapter)
 155 {
 156         return i2c_detect(adapter, &addr_data, eeprom_detect);
 157 }
 158
 159 /* This function is called by i2c_detect */
 160 int eeprom_detect(struct i2c_adapter *adapter, int address, int kind)
 161 {
 162         struct i2c_client *new_client;
 163         struct eeprom_data *data;
 164         int err = 0;
 165
 166         /* prevent 24RF08 corruption */
 167         if (kind < 0)
 168                 i2c_smbus_xfer(adapter, address, 0, 0, 0,
 169                                I2C_SMBUS_QUICK, NULL);
 170
 171         /* There are three ways we can read the EEPROM data:
 172            (1) I2C block reads (faster, but unsupported by most adapters)
 173            (2) Consecutive byte reads (100% overhead)
 174            (3) Regular byte data reads (200% overhead)
 175            The third method is not implemented by this driver because all
 176            known adapters support at least the second. */
 177         if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_BYTE_DATA
 178                                             | I2C_FUNC_SMBUS_BYTE))
 179                 goto exit;
 180
 181         if (!(data = kmalloc(sizeof(struct eeprom_data), GFP_KERNEL))) {
 182                 err = -ENOMEM;
 183                 goto exit;
 184         }
 185         memset(data, 0, sizeof(struct eeprom_data));
 186
 187         new_client = &data->client;
 188         memset(data->data, 0xff, EEPROM_SIZE);
 189         i2c_set_clientdata(new_client, data);
 190         new_client->addr = address;
 191         new_client->adapter = adapter;
 192         new_client->driver = &eeprom_driver;
 193         new_client->flags = 0;
 194
 195         /* Fill in the remaining client fields */
 196         strlcpy(new_client->name, "eeprom", I2C_NAME_SIZE);
 197         data->valid = 0;
 198         init_MUTEX(&data->update_lock);
 199         data->nature = UNKNOWN;
 200
 201         /* Tell the I2C layer a new client has arrived */
 202         if ((err = i2c_attach_client(new_client)))
 203                 goto exit_kfree;
 204
 205         /* Detect the Vaio nature of EEPROMs.
 206            We use the "PCG-" prefix as the signature. */
 207         if (address == 0x57) {
 208                 if (i2c_smbus_read_byte_data(new_client, 0x80) == 'P'
 209                  && i2c_smbus_read_byte(new_client) == 'C'
 210                  && i2c_smbus_read_byte(new_client) == 'G'
 211                  && i2c_smbus_read_byte(new_client) == '-') {
 212                         dev_info(&new_client->dev, "Vaio EEPROM detected, "
 213                                 "enabling password protection\n");
 214                         data->nature = VAIO;
 215                 }
 216         }
 217
 218         /* create the sysfs eeprom file */
 219         sysfs_create_bin_file(&new_client->dev.kobj, &eeprom_attr);
 220
 221         return 0;
 222
 223 exit_kfree:
 224         kfree(data);
 225 exit:
 226         return err;
 227 }
 228
 229 static int eeprom_detach_client(struct i2c_client *client)
 230 {
 231         int err;
 232
 233         err = i2c_detach_client(client);
 234         if (err) {
 235                 dev_err(&client->dev, "Client deregistration failed, client not detached.\n");
 236                 return err;
 237         }
 238
 239         kfree(i2c_get_clientdata(client));
 240
 241         return 0;
 242 }
 243
 244 static int __init eeprom_init(void)
 245 {
 246         return i2c_add_driver(&eeprom_driver);
 247 }
 248
 249 static void __exit eeprom_exit(void)
 250 {
 251         i2c_del_driver(&eeprom_driver);
 252 }
 253
 254
 255 MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl> and "
 256                 "Philip Edelbrock <phil@netroedge.com> and "
 257                 "Greg Kroah-Hartman <greg@kroah.com>");
 258 MODULE_DESCRIPTION("I2C EEPROM driver");
 259 MODULE_LICENSE("GPL");
 260
 261 module_init(eeprom_init);
 262 module_exit(eeprom_exit);