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eeprom.c

/*
    eeprom.c - Part of lm_sensors, Linux kernel modules for hardware
               monitoring
    Copyright (C) 1998, 1999  Frodo Looijaard <frodol@dds.nl> and
                         Philip Edelbrock <phil@netroedge.com>
    Copyright (C) 2003 Greg Kroah-Hartman <greg@kroah.com>
    Copyright (C) 2003 IBM Corp.

    2004-01-16  Jean Delvare <khali@linux-fr.org>
    Divide the eeprom in 32-byte (arbitrary) slices. This significantly
    speeds sensors up, as well as various scripts using the eeprom
    module.

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/jiffies.h>
#include <linux/i2c.h>
#include <linux/mutex.h>

/* Addresses to scan */
static unsigned short normal_i2c[] = { 0x50, 0x51, 0x52, 0x53, 0x54,
                              0x55, 0x56, 0x57, I2C_CLIENT_END };

/* Insmod parameters */
I2C_CLIENT_INSMOD_1(eeprom);


/* Size of EEPROM in bytes */
#define EEPROM_SIZE           256

/* possible types of eeprom devices */
enum eeprom_nature {
      UNKNOWN,
      VAIO,
};

/* Each client has this additional data */
struct eeprom_data {
      struct i2c_client client;
      struct mutex update_lock;
      u8 valid;               /* bitfield, bit!=0 if slice is valid */
      unsigned long last_updated[8];      /* In jiffies, 8 slices */
      u8 data[EEPROM_SIZE];         /* Register values */
      enum eeprom_nature nature;
};


static int eeprom_attach_adapter(struct i2c_adapter *adapter);
static int eeprom_detect(struct i2c_adapter *adapter, int address, int kind);
static int eeprom_detach_client(struct i2c_client *client);

/* This is the driver that will be inserted */
static struct i2c_driver eeprom_driver = {
      .driver = {
            .name = "eeprom",
      },
      .id         = I2C_DRIVERID_EEPROM,
      .attach_adapter   = eeprom_attach_adapter,
      .detach_client    = eeprom_detach_client,
};

static void eeprom_update_client(struct i2c_client *client, u8 slice)
{
      struct eeprom_data *data = i2c_get_clientdata(client);
      int i, j;

      mutex_lock(&data->update_lock);

      if (!(data->valid & (1 << slice)) ||
          time_after(jiffies, data->last_updated[slice] + 300 * HZ)) {
            dev_dbg(&client->dev, "Starting eeprom update, slice %u\n", slice);

            if (i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_READ_I2C_BLOCK)) {
                  for (i = slice << 5; i < (slice + 1) << 5; i += 32)
                        if (i2c_smbus_read_i2c_block_data(client, i,
                                          32, data->data + i)
                                          != 32)
                              goto exit;
            } else {
                  if (i2c_smbus_write_byte(client, slice << 5)) {
                        dev_dbg(&client->dev, "eeprom read start has failed!\n");
                        goto exit;
                  }
                  for (i = slice << 5; i < (slice + 1) << 5; i++) {
                        j = i2c_smbus_read_byte(client);
                        if (j < 0)
                              goto exit;
                        data->data[i] = (u8) j;
                  }
            }
            data->last_updated[slice] = jiffies;
            data->valid |= (1 << slice);
      }
exit:
      mutex_unlock(&data->update_lock);
}

static ssize_t eeprom_read(struct kobject *kobj, struct bin_attribute *bin_attr,
                     char *buf, loff_t off, size_t count)
{
      struct i2c_client *client = to_i2c_client(container_of(kobj, struct device, kobj));
      struct eeprom_data *data = i2c_get_clientdata(client);
      u8 slice;

      if (off > EEPROM_SIZE)
            return 0;
      if (off + count > EEPROM_SIZE)
            count = EEPROM_SIZE - off;

      /* Only refresh slices which contain requested bytes */
      for (slice = off >> 5; slice <= (off + count - 1) >> 5; slice++)
            eeprom_update_client(client, slice);

      /* Hide Vaio private settings to regular users:
         - BIOS passwords: bytes 0x00 to 0x0f
         - UUID: bytes 0x10 to 0x1f
         - Serial number: 0xc0 to 0xdf */
      if (data->nature == VAIO && !capable(CAP_SYS_ADMIN)) {
            int i;

            for (i = 0; i < count; i++) {
                  if ((off + i <= 0x1f) ||
                      (off + i >= 0xc0 && off + i <= 0xdf))
                        buf[i] = 0;
                  else
                        buf[i] = data->data[off + i];
            }
      } else {
            memcpy(buf, &data->data[off], count);
      }

      return count;
}

static struct bin_attribute eeprom_attr = {
      .attr = {
            .name = "eeprom",
            .mode = S_IRUGO,
      },
      .size = EEPROM_SIZE,
      .read = eeprom_read,
};

static int eeprom_attach_adapter(struct i2c_adapter *adapter)
{
      return i2c_probe(adapter, &addr_data, eeprom_detect);
}

/* This function is called by i2c_probe */
static int eeprom_detect(struct i2c_adapter *adapter, int address, int kind)
{
      struct i2c_client *new_client;
      struct eeprom_data *data;
      int err = 0;

      /* There are three ways we can read the EEPROM data:
         (1) I2C block reads (faster, but unsupported by most adapters)
         (2) Consecutive byte reads (100% overhead)
         (3) Regular byte data reads (200% overhead)
         The third method is not implemented by this driver because all
         known adapters support at least the second. */
      if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_BYTE_DATA
                                  | I2C_FUNC_SMBUS_BYTE))
            goto exit;

      if (!(data = kzalloc(sizeof(struct eeprom_data), GFP_KERNEL))) {
            err = -ENOMEM;
            goto exit;
      }

      new_client = &data->client;
      memset(data->data, 0xff, EEPROM_SIZE);
      i2c_set_clientdata(new_client, data);
      new_client->addr = address;
      new_client->adapter = adapter;
      new_client->driver = &eeprom_driver;
      new_client->flags = 0;

      /* Fill in the remaining client fields */
      strlcpy(new_client->name, "eeprom", I2C_NAME_SIZE);
      data->valid = 0;
      mutex_init(&data->update_lock);
      data->nature = UNKNOWN;

      /* Tell the I2C layer a new client has arrived */
      if ((err = i2c_attach_client(new_client)))
            goto exit_kfree;

      /* Detect the Vaio nature of EEPROMs.
         We use the "PCG-" or "VGN-" prefix as the signature. */
      if (address == 0x57) {
            char name[4];

            name[0] = i2c_smbus_read_byte_data(new_client, 0x80);
            name[1] = i2c_smbus_read_byte(new_client);
            name[2] = i2c_smbus_read_byte(new_client);
            name[3] = i2c_smbus_read_byte(new_client);

            if (!memcmp(name, "PCG-", 4) || !memcmp(name, "VGN-", 4)) {
                  dev_info(&new_client->dev, "Vaio EEPROM detected, "
                         "enabling privacy protection\n");
                  data->nature = VAIO;
            }
      }

      /* create the sysfs eeprom file */
      err = sysfs_create_bin_file(&new_client->dev.kobj, &eeprom_attr);
      if (err)
            goto exit_detach;

      return 0;

exit_detach:
      i2c_detach_client(new_client);
exit_kfree:
      kfree(data);
exit:
      return err;
}

static int eeprom_detach_client(struct i2c_client *client)
{
      int err;

      sysfs_remove_bin_file(&client->dev.kobj, &eeprom_attr);

      err = i2c_detach_client(client);
      if (err)
            return err;

      kfree(i2c_get_clientdata(client));

      return 0;
}

static int __init eeprom_init(void)
{
      return i2c_add_driver(&eeprom_driver);
}

static void __exit eeprom_exit(void)
{
      i2c_del_driver(&eeprom_driver);
}


MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl> and "
            "Philip Edelbrock <phil@netroedge.com> and "
            "Greg Kroah-Hartman <greg@kroah.com>");
MODULE_DESCRIPTION("I2C EEPROM driver");
MODULE_LICENSE("GPL");

module_init(eeprom_init);
module_exit(eeprom_exit);

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