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c-1.in.c

/* i2c-core.c - a device driver for the iic-bus interface              */
/* ------------------------------------------------------------------------- */
/*   Copyright (C) 1995-99 Simon G. Vogl

    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.                */
/* ------------------------------------------------------------------------- */

/* With some changes from Kyösti Mälkki <kmalkki@cc.hut.fi>.
   All SMBus-related things are written by Frodo Looijaard <frodol@dds.nl>
   SMBus 2.0 support by Mark Studebaker <mdsxyz123@yahoo.com>                */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/i2c.h>
#include <linux/init.h>
#include <linux/idr.h>
#include <linux/seq_file.h>
#include <asm/uaccess.h>


static LIST_HEAD(adapters);
static LIST_HEAD(drivers);
static DECLARE_MUTEX(core_lists);
static DEFINE_IDR(i2c_adapter_idr);

static int i2c_device_match(struct device *dev, struct device_driver *drv)
{
      return 1;
}

static int i2c_bus_suspend(struct device * dev, pm_message_t state)
{
      int rc = 0;

      if (dev->driver && dev->driver->suspend)
            rc = dev->driver->suspend(dev,state,0);
      return rc;
}

static int i2c_bus_resume(struct device * dev)
{
      int rc = 0;
      
      if (dev->driver && dev->driver->resume)
            rc = dev->driver->resume(dev,0);
      return rc;
}

struct bus_type i2c_bus_type = {
      .name =     "i2c",
      .match = i2c_device_match,
      .suspend = i2c_bus_suspend,
      .resume = i2c_bus_resume,
};

static int i2c_device_probe(struct device *dev)
{
      return -ENODEV;
}

static int i2c_device_remove(struct device *dev)
{
      return 0;
}

void i2c_adapter_dev_release(struct device *dev)
{
      struct i2c_adapter *adap = dev_to_i2c_adapter(dev);
      complete(&adap->dev_released);
}

struct device_driver i2c_adapter_driver = {
      .name =     "i2c_adapter",
      .bus = &i2c_bus_type,
      .probe = i2c_device_probe,
      .remove = i2c_device_remove,
};

static void i2c_adapter_class_dev_release(struct class_device *dev)
{
      struct i2c_adapter *adap = class_dev_to_i2c_adapter(dev);
      complete(&adap->class_dev_released);
}

struct class i2c_adapter_class = {
      .name =     "i2c-adapter",
      .release =&i2c_adapter_class_dev_release,
};

static ssize_t show_adapter_name(struct device *dev, struct device_attribute *attr, char *buf)
{
      struct i2c_adapter *adap = dev_to_i2c_adapter(dev);
      return sprintf(buf, "%s\n", adap->name);
}
static DEVICE_ATTR(name, S_IRUGO, show_adapter_name, NULL);


static void i2c_client_release(struct device *dev)
{
      struct i2c_client *client = to_i2c_client(dev);
      complete(&client->released);
}

static ssize_t show_client_name(struct device *dev, struct device_attribute *attr, char *buf)
{
      struct i2c_client *client = to_i2c_client(dev);
      return sprintf(buf, "%s\n", client->name);
}

/*
 * We can't use the DEVICE_ATTR() macro here as we want the same filename for a
 * different type of a device.  So beware if the DEVICE_ATTR() macro ever
 * changes, this definition will also have to change.
 */
static struct device_attribute dev_attr_client_name = {
      .attr = {.name = "name", .mode = S_IRUGO, .owner = THIS_MODULE },
      .show   =  &show_client_name,
};


/* ---------------------------------------------------
 * registering functions
 * ---------------------------------------------------
 */

/* -----
 * i2c_add_adapter is called from within the algorithm layer,
 * when a new hw adapter registers. A new device is register to be
 * available for clients.
 */
int i2c_add_adapter(struct i2c_adapter *adap)
{
      int id, res = 0;
      struct list_head   *item;
      struct i2c_driver  *driver;

      down(&core_lists);

      if (idr_pre_get(&i2c_adapter_idr, GFP_KERNEL) == 0) {
            res = -ENOMEM;
            goto out_unlock;
      }

      res = idr_get_new(&i2c_adapter_idr, adap, &id);
      if (res < 0) {
            if (res == -EAGAIN)
                  res = -ENOMEM;
            goto out_unlock;
      }

      adap->nr =  id & MAX_ID_MASK;
      init_MUTEX(&adap->bus_lock);
      init_MUTEX(&adap->clist_lock);
      list_add_tail(&adap->list,&adapters);
      INIT_LIST_HEAD(&adap->clients);

      /* Add the adapter to the driver core.
       * If the parent pointer is not set up,
       * we add this adapter to the host bus.
       */
      if (adap->dev.parent == NULL)
            adap->dev.parent = &platform_bus;
      sprintf(adap->dev.bus_id, "i2c-%d", adap->nr);
      adap->dev.driver = &i2c_adapter_driver;
      adap->dev.release = &i2c_adapter_dev_release;
      device_register(&adap->dev);
      device_create_file(&adap->dev, &dev_attr_name);

      /* Add this adapter to the i2c_adapter class */
      memset(&adap->class_dev, 0x00, sizeof(struct class_device));
      adap->class_dev.dev = &adap->dev;
      adap->class_dev.class = &i2c_adapter_class;
      strlcpy(adap->class_dev.class_id, adap->dev.bus_id, BUS_ID_SIZE);
      class_device_register(&adap->class_dev);

      dev_dbg(&adap->dev, "adapter [%s] registered\n", adap->name);

      /* inform drivers of new adapters */
      list_for_each(item,&drivers) {
            driver = list_entry(item, struct i2c_driver, list);
            if (driver->flags & I2C_DF_NOTIFY)
            /* We ignore the return code; if it fails, too bad */
            driver->attach_adapter(adap);
      }

out_unlock:
      up(&core_lists);
      return res;
}


int i2c_del_adapter(struct i2c_adapter *adap)
{
      struct list_head  *item, *_n;
      struct i2c_adapter *adap_from_list;
      struct i2c_driver *driver;
      struct i2c_client *client;
      int res = 0;

      down(&core_lists);

      /* First make sure that this adapter was ever added */
      list_for_each_entry(adap_from_list, &adapters, list) {
            if (adap_from_list == adap)
                  break;
      }
      if (adap_from_list != adap) {
            pr_debug("i2c-core: attempting to delete unregistered "
                   "adapter [%s]\n", adap->name);
            res = -EINVAL;
            goto out_unlock;
      }

      list_for_each(item,&drivers) {
            driver = list_entry(item, struct i2c_driver, list);
            if (driver->detach_adapter)
                  if ((res = driver->detach_adapter(adap))) {
                        dev_err(&adap->dev, "detach_adapter failed "
                              "for driver [%s]\n", driver->name);
                        goto out_unlock;
                  }
      }

      /* detach any active clients. This must be done first, because
       * it can fail; in which case we give up. */
      list_for_each_safe(item, _n, &adap->clients) {
            client = list_entry(item, struct i2c_client, list);

            /* detaching devices is unconditional of the set notify
             * flag, as _all_ clients that reside on the adapter
             * must be deleted, as this would cause invalid states.
             */
            if ((res=client->driver->detach_client(client))) {
                  dev_err(&adap->dev, "detach_client failed for client "
                        "[%s] at address 0x%02x\n", client->name,
                        client->addr);
                  goto out_unlock;
            }
      }

      /* clean up the sysfs representation */
      init_completion(&adap->dev_released);
      init_completion(&adap->class_dev_released);
      class_device_unregister(&adap->class_dev);
      device_remove_file(&adap->dev, &dev_attr_name);
      device_unregister(&adap->dev);
      list_del(&adap->list);

      /* wait for sysfs to drop all references */
      wait_for_completion(&adap->dev_released);
      wait_for_completion(&adap->class_dev_released);

      /* free dynamically allocated bus id */
      idr_remove(&i2c_adapter_idr, adap->nr);

      dev_dbg(&adap->dev, "adapter [%s] unregistered\n", adap->name);

 out_unlock:
      up(&core_lists);
      return res;
}


/* -----
 * What follows is the "upwards" interface: commands for talking to clients,
 * which implement the functions to access the physical information of the
 * chips.
 */

int i2c_add_driver(struct i2c_driver *driver)
{
      struct list_head   *item;
      struct i2c_adapter *adapter;
      int res = 0;

      down(&core_lists);

      /* add the driver to the list of i2c drivers in the driver core */
      driver->driver.name = driver->name;
      driver->driver.bus = &i2c_bus_type;
      driver->driver.probe = i2c_device_probe;
      driver->driver.remove = i2c_device_remove;

      res = driver_register(&driver->driver);
      if (res)
            goto out_unlock;
      
      list_add_tail(&driver->list,&drivers);
      pr_debug("i2c-core: driver [%s] registered\n", driver->name);

      /* now look for instances of driver on our adapters */
      if (driver->flags & I2C_DF_NOTIFY) {
            list_for_each(item,&adapters) {
                  adapter = list_entry(item, struct i2c_adapter, list);
                  driver->attach_adapter(adapter);
            }
      }

 out_unlock:
      up(&core_lists);
      return res;
}

int i2c_del_driver(struct i2c_driver *driver)
{
      struct list_head   *item1, *item2, *_n;
      struct i2c_client  *client;
      struct i2c_adapter *adap;
      
      int res = 0;

      down(&core_lists);

      /* Have a look at each adapter, if clients of this driver are still
       * attached. If so, detach them to be able to kill the driver
       * afterwards.
       *
       * Removing clients does not depend on the notify flag, else
       * invalid operation might (will!) result, when using stale client
       * pointers.
       */
      list_for_each(item1,&adapters) {
            adap = list_entry(item1, struct i2c_adapter, list);
            if (driver->detach_adapter) {
                  if ((res = driver->detach_adapter(adap))) {
                        dev_err(&adap->dev, "detach_adapter failed "
                              "for driver [%s]\n", driver->name);
                        goto out_unlock;
                  }
            } else {
                  list_for_each_safe(item2, _n, &adap->clients) {
                        client = list_entry(item2, struct i2c_client, list);
                        if (client->driver != driver)
                              continue;
                        dev_dbg(&adap->dev, "detaching client [%s] "
                              "at 0x%02x\n", client->name,
                              client->addr);
                        if ((res = driver->detach_client(client))) {
                              dev_err(&adap->dev, "detach_client "
                                    "failed for client [%s] at "
                                    "0x%02x\n", client->name,
                                    client->addr);
                              goto out_unlock;
                        }
                  }
            }
      }

      driver_unregister(&driver->driver);
      list_del(&driver->list);
      pr_debug("i2c-core: driver [%s] unregistered\n", driver->name);

 out_unlock:
      up(&core_lists);
      return 0;
}

static int __i2c_check_addr(struct i2c_adapter *adapter, unsigned int addr)
{
      struct list_head   *item;
      struct i2c_client  *client;

      list_for_each(item,&adapter->clients) {
            client = list_entry(item, struct i2c_client, list);
            if (client->addr == addr)
                  return -EBUSY;
      }
      return 0;
}

int i2c_check_addr(struct i2c_adapter *adapter, int addr)
{
      int rval;

      down(&adapter->clist_lock);
      rval = __i2c_check_addr(adapter, addr);
      up(&adapter->clist_lock);

      return rval;
}

int i2c_attach_client(struct i2c_client *client)
{
      struct i2c_adapter *adapter = client->adapter;

      down(&adapter->clist_lock);
      if (__i2c_check_addr(client->adapter, client->addr)) {
            up(&adapter->clist_lock);
            return -EBUSY;
      }
      list_add_tail(&client->list,&adapter->clients);
      up(&adapter->clist_lock);
      
      if (adapter->client_register)  {
            if (adapter->client_register(client))  {
                  dev_dbg(&adapter->dev, "client_register "
                        "failed for client [%s] at 0x%02x\n",
                        client->name, client->addr);
            }
      }

      if (client->flags & I2C_CLIENT_ALLOW_USE)
            client->usage_count = 0;

      client->dev.parent = &client->adapter->dev;
      client->dev.driver = &client->driver->driver;
      client->dev.bus = &i2c_bus_type;
      client->dev.release = &i2c_client_release;
      
      snprintf(&client->dev.bus_id[0], sizeof(client->dev.bus_id),
            "%d-%04x", i2c_adapter_id(adapter), client->addr);
      dev_dbg(&adapter->dev, "client [%s] registered with bus id %s\n",
            client->name, client->dev.bus_id);
      device_register(&client->dev);
      device_create_file(&client->dev, &dev_attr_client_name);
      
      return 0;
}


int i2c_detach_client(struct i2c_client *client)
{
      struct i2c_adapter *adapter = client->adapter;
      int res = 0;
      
      if ((client->flags & I2C_CLIENT_ALLOW_USE)
       && (client->usage_count > 0)) {
            dev_warn(&client->dev, "Client [%s] still busy, "
                   "can't detach\n", client->name);
            return -EBUSY;
      }

      if (adapter->client_unregister)  {
            res = adapter->client_unregister(client);
            if (res) {
                  dev_err(&client->dev,
                        "client_unregister [%s] failed, "
                        "client not detached\n", client->name);
                  goto out;
            }
      }

      down(&adapter->clist_lock);
      list_del(&client->list);
      init_completion(&client->released);
      device_remove_file(&client->dev, &dev_attr_client_name);
      device_unregister(&client->dev);
      up(&adapter->clist_lock);
      wait_for_completion(&client->released);

 out:
      return res;
}

static int i2c_inc_use_client(struct i2c_client *client)
{

      if (!try_module_get(client->driver->owner))
            return -ENODEV;
      if (!try_module_get(client->adapter->owner)) {
            module_put(client->driver->owner);
            return -ENODEV;
      }

      return 0;
}

static void i2c_dec_use_client(struct i2c_client *client)
{
      module_put(client->driver->owner);
      module_put(client->adapter->owner);
}

int i2c_use_client(struct i2c_client *client)
{
      int ret;

      ret = i2c_inc_use_client(client);
      if (ret)
            return ret;

      if (client->flags & I2C_CLIENT_ALLOW_USE) {
            if (client->flags & I2C_CLIENT_ALLOW_MULTIPLE_USE)
                  client->usage_count++;
            else if (client->usage_count > 0)
                  goto busy;
            else
                  client->usage_count++;
      }

      return 0;
 busy:
      i2c_dec_use_client(client);
      return -EBUSY;
}

int i2c_release_client(struct i2c_client *client)
{
      if(client->flags & I2C_CLIENT_ALLOW_USE) {
            if(client->usage_count>0)
                  client->usage_count--;
            else {
                  pr_debug("i2c-core: %s used one too many times\n",
                        __FUNCTION__);
                  return -EPERM;
            }
      }
      
      i2c_dec_use_client(client);
      
      return 0;
}

void i2c_clients_command(struct i2c_adapter *adap, unsigned int cmd, void *arg)
{
      struct list_head  *item;
      struct i2c_client *client;

      down(&adap->clist_lock);
      list_for_each(item,&adap->clients) {
            client = list_entry(item, struct i2c_client, list);
            if (!try_module_get(client->driver->owner))
                  continue;
            if (NULL != client->driver->command) {
                  up(&adap->clist_lock);
                  client->driver->command(client,cmd,arg);
                  down(&adap->clist_lock);
            }
            module_put(client->driver->owner);
       }
       up(&adap->clist_lock);
}

static int __init i2c_init(void)
{
      int retval;

      retval = bus_register(&i2c_bus_type);
      if (retval)
            return retval;
      retval = driver_register(&i2c_adapter_driver);
      if (retval)
            return retval;
      return class_register(&i2c_adapter_class);
}

static void __exit i2c_exit(void)
{
      class_unregister(&i2c_adapter_class);
      driver_unregister(&i2c_adapter_driver);
      bus_unregister(&i2c_bus_type);
}

subsys_initcall(i2c_init);
module_exit(i2c_exit);

/* ----------------------------------------------------
 * the functional interface to the i2c busses.
 * ----------------------------------------------------
 */

int i2c_transfer(struct i2c_adapter * adap, struct i2c_msg *msgs, int num)
{
      int ret;

      if (adap->algo->master_xfer) {
#ifdef DEBUG
            for (ret = 0; ret < num; ret++) {
                  dev_dbg(&adap->dev, "master_xfer[%d] %c, addr=0x%02x, "
                        "len=%d\n", ret, msgs[ret].flags & I2C_M_RD ?
                        'R' : 'W', msgs[ret].addr, msgs[ret].len);
            }
#endif

            down(&adap->bus_lock);
            ret = adap->algo->master_xfer(adap,msgs,num);
            up(&adap->bus_lock);

            return ret;
      } else {
            dev_dbg(&adap->dev, "I2C level transfers not supported\n");
            return -ENOSYS;
      }
}

int i2c_master_send(struct i2c_client *client,const char *buf ,int count)
{
      int ret;
      struct i2c_adapter *adap=client->adapter;
      struct i2c_msg msg;

      msg.addr = client->addr;
      msg.flags = client->flags & I2C_M_TEN;
      msg.len = count;
      msg.buf = (char *)buf;
      
      ret = i2c_transfer(adap, &msg, 1);

      /* If everything went ok (i.e. 1 msg transmitted), return #bytes
         transmitted, else error code. */
      return (ret == 1) ? count : ret;
}

int i2c_master_recv(struct i2c_client *client, char *buf ,int count)
{
      struct i2c_adapter *adap=client->adapter;
      struct i2c_msg msg;
      int ret;

      msg.addr = client->addr;
      msg.flags = client->flags & I2C_M_TEN;
      msg.flags |= I2C_M_RD;
      msg.len = count;
      msg.buf = buf;

      ret = i2c_transfer(adap, &msg, 1);

      /* If everything went ok (i.e. 1 msg transmitted), return #bytes
         transmitted, else error code. */
      return (ret == 1) ? count : ret;
}


int i2c_control(struct i2c_client *client,
      unsigned int cmd, unsigned long arg)
{
      int ret = 0;
      struct i2c_adapter *adap = client->adapter;

      dev_dbg(&client->adapter->dev, "i2c ioctl, cmd: 0x%x, arg: %#lx\n", cmd, arg);
      switch (cmd) {
            case I2C_RETRIES:
                  adap->retries = arg;
                  break;
            case I2C_TIMEOUT:
                  adap->timeout = arg;
                  break;
            default:
                  if (adap->algo->algo_control!=NULL)
                        ret = adap->algo->algo_control(adap,cmd,arg);
      }
      return ret;
}

/* ----------------------------------------------------
 * the i2c address scanning function
 * Will not work for 10-bit addresses!
 * ----------------------------------------------------
 */
static int i2c_probe_address(struct i2c_adapter *adapter, int addr, int kind,
                       int (*found_proc) (struct i2c_adapter *, int, int))
{
      int err;

      /* Make sure the address is valid */
      if (addr < 0x03 || addr > 0x77) {
            dev_warn(&adapter->dev, "Invalid probe address 0x%02x\n",
                   addr);
            return -EINVAL;
      }

      /* Skip if already in use */
      if (i2c_check_addr(adapter, addr))
            return 0;

      /* Make sure there is something at this address, unless forced */
      if (kind < 0) {
            if (i2c_smbus_xfer(adapter, addr, 0, 0, 0,
                           I2C_SMBUS_QUICK, NULL) < 0)
                  return 0;

            /* prevent 24RF08 corruption */
            if ((addr & ~0x0f) == 0x50)
                  i2c_smbus_xfer(adapter, addr, 0, 0, 0,
                               I2C_SMBUS_QUICK, NULL);
      }

      /* Finally call the custom detection function */
      err = found_proc(adapter, addr, kind);

      /* -ENODEV can be returned if there is a chip at the given address
         but it isn't supported by this chip driver. We catch it here as
         this isn't an error. */
      return (err == -ENODEV) ? 0 : err;
}

int i2c_probe(struct i2c_adapter *adapter,
            struct i2c_client_address_data *address_data,
            int (*found_proc) (struct i2c_adapter *, int, int))
{
      int i, err;
      int adap_id = i2c_adapter_id(adapter);

      /* Forget it if we can't probe using SMBUS_QUICK */
      if (! i2c_check_functionality(adapter,I2C_FUNC_SMBUS_QUICK))
            return -1;

      /* Force entries are done first, and are not affected by ignore
         entries */
      if (address_data->forces) {
            unsigned short **forces = address_data->forces;
            int kind;

            for (kind = 0; forces[kind]; kind++) {
                  for (i = 0; forces[kind][i] != I2C_CLIENT_END;
                       i += 2) {
                        if (forces[kind][i] == adap_id
                         || forces[kind][i] == ANY_I2C_BUS) {
                              dev_dbg(&adapter->dev, "found force "
                                    "parameter for adapter %d, "
                                    "addr 0x%02x, kind %d\n",
                                    adap_id, forces[kind][i + 1],
                                    kind);
                              err = i2c_probe_address(adapter,
                                    forces[kind][i + 1],
                                    kind, found_proc);
                              if (err)
                                    return err;
                        }
                  }
            }
      }

      /* Probe entries are done second, and are not affected by ignore
         entries either */
      for (i = 0; address_data->probe[i] != I2C_CLIENT_END; i += 2) {
            if (address_data->probe[i] == adap_id
             || address_data->probe[i] == ANY_I2C_BUS) {
                  dev_dbg(&adapter->dev, "found probe parameter for "
                        "adapter %d, addr 0x%02x\n", adap_id,
                        address_data->probe[i + 1]);
                  err = i2c_probe_address(adapter,
                                    address_data->probe[i + 1],
                                    -1, found_proc);
                  if (err)
                        return err;
            }
      }

      /* Normal entries are done last, unless shadowed by an ignore entry */
      for (i = 0; address_data->normal_i2c[i] != I2C_CLIENT_END; i += 1) {
            int j, ignore;

            ignore = 0;
            for (j = 0; address_data->ignore[j] != I2C_CLIENT_END;
                 j += 2) {
                  if ((address_data->ignore[j] == adap_id ||
                       address_data->ignore[j] == ANY_I2C_BUS)
                   && address_data->ignore[j + 1]
                      == address_data->normal_i2c[i]) {
                        dev_dbg(&adapter->dev, "found ignore "
                              "parameter for adapter %d, "
                              "addr 0x%02x\n", adap_id,
                              address_data->ignore[j + 1]);
                  }
                  ignore = 1;
                  break;
            }
            if (ignore)
                  continue;

            dev_dbg(&adapter->dev, "found normal entry for adapter %d, "
                  "addr 0x%02x\n", adap_id,
                  address_data->normal_i2c[i]);
            err = i2c_probe_address(adapter, address_data->normal_i2c[i],
                              -1, found_proc);
            if (err)
                  return err;
      }

      return 0;
}

struct i2c_adapter* i2c_get_adapter(int id)
{
      struct i2c_adapter *adapter;
      
      down(&core_lists);
      adapter = (struct i2c_adapter *)idr_find(&i2c_adapter_idr, id);
      if (adapter && !try_module_get(adapter->owner))
            adapter = NULL;

      up(&core_lists);
      return adapter;
}

void i2c_put_adapter(struct i2c_adapter *adap)
{
      module_put(adap->owner);
}

/* The SMBus parts */

#define POLY    (0x1070U << 3)
static u8
crc8(u16 data)
{
      int i;

      for(i = 0; i < 8; i++) {
            if (data & 0x8000)
                  data = data ^ POLY;
            data = data << 1;
      }
      return (u8)(data >> 8);
}

/* CRC over count bytes in the first array plus the bytes in the rest
   array if it is non-null. rest[0] is the (length of rest) - 1
   and is included. */
static u8 i2c_smbus_partial_pec(u8 crc, int count, u8 *first, u8 *rest)
{
      int i;

      for(i = 0; i < count; i++)
            crc = crc8((crc ^ first[i]) << 8);
      if(rest != NULL)
            for(i = 0; i <= rest[0]; i++)
                  crc = crc8((crc ^ rest[i]) << 8);
      return crc;
}

static u8 i2c_smbus_pec(int count, u8 *first, u8 *rest)
{
      return i2c_smbus_partial_pec(0, count, first, rest);
}

/* Returns new "size" (transaction type)
   Note that we convert byte to byte_data and byte_data to word_data
   rather than invent new xxx_PEC transactions. */
static int i2c_smbus_add_pec(u16 addr, u8 command, int size,
                       union i2c_smbus_data *data)
{
      u8 buf[3];

      buf[0] = addr << 1;
      buf[1] = command;
      switch(size) {
            case I2C_SMBUS_BYTE:
                  data->byte = i2c_smbus_pec(2, buf, NULL);
                  size = I2C_SMBUS_BYTE_DATA;
                  break;
            case I2C_SMBUS_BYTE_DATA:
                  buf[2] = data->byte;
                  data->word = buf[2] ||
                              (i2c_smbus_pec(3, buf, NULL) << 8);
                  size = I2C_SMBUS_WORD_DATA;
                  break;
            case I2C_SMBUS_WORD_DATA:
                  /* unsupported */
                  break;
            case I2C_SMBUS_BLOCK_DATA:
                  data->block[data->block[0] + 1] =
                               i2c_smbus_pec(2, buf, data->block);
                  size = I2C_SMBUS_BLOCK_DATA_PEC;
                  break;
      }
      return size;      
}

static int i2c_smbus_check_pec(u16 addr, u8 command, int size, u8 partial,
                         union i2c_smbus_data *data)
{
      u8 buf[3], rpec, cpec;

      buf[1] = command;
      switch(size) {
            case I2C_SMBUS_BYTE_DATA:
                  buf[0] = (addr << 1) | 1;
                  cpec = i2c_smbus_pec(2, buf, NULL);
                  rpec = data->byte;
                  break;
            case I2C_SMBUS_WORD_DATA:
                  buf[0] = (addr << 1) | 1;
                  buf[2] = data->word & 0xff;
                  cpec = i2c_smbus_pec(3, buf, NULL);
                  rpec = data->word >> 8;
                  break;
            case I2C_SMBUS_WORD_DATA_PEC:
                  /* unsupported */
                  cpec = rpec = 0;
                  break;
            case I2C_SMBUS_PROC_CALL_PEC:
                  /* unsupported */
                  cpec = rpec = 0;
                  break;
            case I2C_SMBUS_BLOCK_DATA_PEC:
                  buf[0] = (addr << 1);
                  buf[2] = (addr << 1) | 1;
                  cpec = i2c_smbus_pec(3, buf, data->block);
                  rpec = data->block[data->block[0] + 1];
                  break;
            case I2C_SMBUS_BLOCK_PROC_CALL_PEC:
                  buf[0] = (addr << 1) | 1;
                  rpec = i2c_smbus_partial_pec(partial, 1,
                                               buf, data->block);
                  cpec = data->block[data->block[0] + 1];
                  break;
            default:
                  cpec = rpec = 0;
                  break;
      }
      if (rpec != cpec) {
            pr_debug("i2c-core: Bad PEC 0x%02x vs. 0x%02x\n",
                  rpec, cpec);
            return -1;
      }
      return 0;   
}

s32 i2c_smbus_write_quick(struct i2c_client *client, u8 value)
{
      return i2c_smbus_xfer(client->adapter,client->addr,client->flags,
                            value,0,I2C_SMBUS_QUICK,NULL);
}

s32 i2c_smbus_read_byte(struct i2c_client *client)
{
      union i2c_smbus_data data;
      if (i2c_smbus_xfer(client->adapter,client->addr,client->flags,
                         I2C_SMBUS_READ,0,I2C_SMBUS_BYTE, &data))
            return -1;
      else
            return 0x0FF & data.byte;
}

s32 i2c_smbus_write_byte(struct i2c_client *client, u8 value)
{
      union i2c_smbus_data data;    /* only for PEC */
      return i2c_smbus_xfer(client->adapter,client->addr,client->flags,
                            I2C_SMBUS_WRITE,value, I2C_SMBUS_BYTE,&data);
}

s32 i2c_smbus_read_byte_data(struct i2c_client *client, u8 command)
{
      union i2c_smbus_data data;
      if (i2c_smbus_xfer(client->adapter,client->addr,client->flags,
                         I2C_SMBUS_READ,command, I2C_SMBUS_BYTE_DATA,&data))
            return -1;
      else
            return 0x0FF & data.byte;
}

s32 i2c_smbus_write_byte_data(struct i2c_client *client, u8 command, u8 value)
{
      union i2c_smbus_data data;
      data.byte = value;
      return i2c_smbus_xfer(client->adapter,client->addr,client->flags,
                            I2C_SMBUS_WRITE,command,
                            I2C_SMBUS_BYTE_DATA,&data);
}

s32 i2c_smbus_read_word_data(struct i2c_client *client, u8 command)
{
      union i2c_smbus_data data;
      if (i2c_smbus_xfer(client->adapter,client->addr,client->flags,
                         I2C_SMBUS_READ,command, I2C_SMBUS_WORD_DATA, &data))
            return -1;
      else
            return 0x0FFFF & data.word;
}

s32 i2c_smbus_write_word_data(struct i2c_client *client, u8 command, u16 value)
{
      union i2c_smbus_data data;
      data.word = value;
      return i2c_smbus_xfer(client->adapter,client->addr,client->flags,
                            I2C_SMBUS_WRITE,command,
                            I2C_SMBUS_WORD_DATA,&data);
}

s32 i2c_smbus_write_block_data(struct i2c_client *client, u8 command,
                         u8 length, u8 *values)
{
      union i2c_smbus_data data;
      int i;
      if (length > I2C_SMBUS_BLOCK_MAX)
            length = I2C_SMBUS_BLOCK_MAX;
      for (i = 1; i <= length; i++)
            data.block[i] = values[i-1];
      data.block[0] = length;
      return i2c_smbus_xfer(client->adapter,client->addr,client->flags,
                        I2C_SMBUS_WRITE,command,
                        I2C_SMBUS_BLOCK_DATA,&data);
}

/* Returns the number of read bytes */
s32 i2c_smbus_read_i2c_block_data(struct i2c_client *client, u8 command, u8 *values)
{
      union i2c_smbus_data data;
      int i;
      if (i2c_smbus_xfer(client->adapter,client->addr,client->flags,
                            I2C_SMBUS_READ,command,
                            I2C_SMBUS_I2C_BLOCK_DATA,&data))
            return -1;
      else {
            for (i = 1; i <= data.block[0]; i++)
                  values[i-1] = data.block[i];
            return data.block[0];
      }
}

/* Simulate a SMBus command using the i2c protocol
   No checking of parameters is done!  */
static s32 i2c_smbus_xfer_emulated(struct i2c_adapter * adapter, u16 addr,
                                   unsigned short flags,
                                   char read_write, u8 command, int size,
                                   union i2c_smbus_data * data)
{
      /* So we need to generate a series of msgs. In the case of writing, we
        need to use only one message; when reading, we need two. We initialize
        most things with sane defaults, to keep the code below somewhat
        simpler. */
      unsigned char msgbuf0[34];
      unsigned char msgbuf1[34];
      int num = read_write == I2C_SMBUS_READ?2:1;
      struct i2c_msg msg[2] = { { addr, flags, 1, msgbuf0 },
                                { addr, flags | I2C_M_RD, 0, msgbuf1 }
                              };
      int i;

      msgbuf0[0] = command;
      switch(size) {
      case I2C_SMBUS_QUICK:
            msg[0].len = 0;
            /* Special case: The read/write field is used as data */
            msg[0].flags = flags | (read_write==I2C_SMBUS_READ)?I2C_M_RD:0;
            num = 1;
            break;
      case I2C_SMBUS_BYTE:
            if (read_write == I2C_SMBUS_READ) {
                  /* Special case: only a read! */
                  msg[0].flags = I2C_M_RD | flags;
                  num = 1;
            }
            break;
      case I2C_SMBUS_BYTE_DATA:
            if (read_write == I2C_SMBUS_READ)
                  msg[1].len = 1;
            else {
                  msg[0].len = 2;
                  msgbuf0[1] = data->byte;
            }
            break;
      case I2C_SMBUS_WORD_DATA:
            if (read_write == I2C_SMBUS_READ)
                  msg[1].len = 2;
            else {
                  msg[0].len=3;
                  msgbuf0[1] = data->word & 0xff;
                  msgbuf0[2] = (data->word >> 8) & 0xff;
            }
            break;
      case I2C_SMBUS_PROC_CALL:
            num = 2; /* Special case */
            read_write = I2C_SMBUS_READ;
            msg[0].len = 3;
            msg[1].len = 2;
            msgbuf0[1] = data->word & 0xff;
            msgbuf0[2] = (data->word >> 8) & 0xff;
            break;
      case I2C_SMBUS_BLOCK_DATA:
      case I2C_SMBUS_BLOCK_DATA_PEC:
            if (read_write == I2C_SMBUS_READ) {
                  dev_err(&adapter->dev, "Block read not supported "
                         "under I2C emulation!\n");
                  return -1;
            } else {
                  msg[0].len = data->block[0] + 2;
                  if (msg[0].len > I2C_SMBUS_BLOCK_MAX + 2) {
                        dev_err(&adapter->dev, "smbus_access called with "
                               "invalid block write size (%d)\n",
                               data->block[0]);
                        return -1;
                  }
                  if(size == I2C_SMBUS_BLOCK_DATA_PEC)
                        (msg[0].len)++;
                  for (i = 1; i <= msg[0].len; i++)
                        msgbuf0[i] = data->block[i-1];
            }
            break;
      case I2C_SMBUS_BLOCK_PROC_CALL:
      case I2C_SMBUS_BLOCK_PROC_CALL_PEC:
            dev_dbg(&adapter->dev, "Block process call not supported "
                   "under I2C emulation!\n");
            return -1;
      case I2C_SMBUS_I2C_BLOCK_DATA:
            if (read_write == I2C_SMBUS_READ) {
                  msg[1].len = I2C_SMBUS_I2C_BLOCK_MAX;
            } else {
                  msg[0].len = data->block[0] + 1;
                  if (msg[0].len > I2C_SMBUS_I2C_BLOCK_MAX + 1) {
                        dev_err(&adapter->dev, "i2c_smbus_xfer_emulated called with "
                               "invalid block write size (%d)\n",
                               data->block[0]);
                        return -1;
                  }
                  for (i = 1; i <= data->block[0]; i++)
                        msgbuf0[i] = data->block[i];
            }
            break;
      default:
            dev_err(&adapter->dev, "smbus_access called with invalid size (%d)\n",
                   size);
            return -1;
      }

      if (i2c_transfer(adapter, msg, num) < 0)
            return -1;

      if (read_write == I2C_SMBUS_READ)
            switch(size) {
                  case I2C_SMBUS_BYTE:
                        data->byte = msgbuf0[0];
                        break;
                  case I2C_SMBUS_BYTE_DATA:
                        data->byte = msgbuf1[0];
                        break;
                  case I2C_SMBUS_WORD_DATA:
                  case I2C_SMBUS_PROC_CALL:
                        data->word = msgbuf1[0] | (msgbuf1[1] << 8);
                        break;
                  case I2C_SMBUS_I2C_BLOCK_DATA:
                        /* fixed at 32 for now */
                        data->block[0] = I2C_SMBUS_I2C_BLOCK_MAX;
                        for (i = 0; i < I2C_SMBUS_I2C_BLOCK_MAX; i++)
                              data->block[i+1] = msgbuf1[i];
                        break;
            }
      return 0;
}


s32 i2c_smbus_xfer(struct i2c_adapter * adapter, u16 addr, unsigned short flags,
                   char read_write, u8 command, int size,
                   union i2c_smbus_data * data)
{
      s32 res;
      int swpec = 0;
      u8 partial = 0;

      flags &= I2C_M_TEN | I2C_CLIENT_PEC;
      if((flags & I2C_CLIENT_PEC) &&
         !(i2c_check_functionality(adapter, I2C_FUNC_SMBUS_HWPEC_CALC))) {
            swpec = 1;
            if(read_write == I2C_SMBUS_READ &&
               size == I2C_SMBUS_BLOCK_DATA)
                  size = I2C_SMBUS_BLOCK_DATA_PEC;
            else if(size == I2C_SMBUS_PROC_CALL)
                  size = I2C_SMBUS_PROC_CALL_PEC;
            else if(size == I2C_SMBUS_BLOCK_PROC_CALL) {
                  i2c_smbus_add_pec(addr, command,
                                      I2C_SMBUS_BLOCK_DATA, data);
                  partial = data->block[data->block[0] + 1];
                  size = I2C_SMBUS_BLOCK_PROC_CALL_PEC;
            } else if(read_write == I2C_SMBUS_WRITE &&
                      size != I2C_SMBUS_QUICK &&
                      size != I2C_SMBUS_I2C_BLOCK_DATA)
                  size = i2c_smbus_add_pec(addr, command, size, data);
      }

      if (adapter->algo->smbus_xfer) {
            down(&adapter->bus_lock);
            res = adapter->algo->smbus_xfer(adapter,addr,flags,read_write,
                                            command,size,data);
            up(&adapter->bus_lock);
      } else
            res = i2c_smbus_xfer_emulated(adapter,addr,flags,read_write,
                                            command,size,data);

      if(res >= 0 && swpec &&
         size != I2C_SMBUS_QUICK && size != I2C_SMBUS_I2C_BLOCK_DATA &&
         (read_write == I2C_SMBUS_READ || size == I2C_SMBUS_PROC_CALL_PEC ||
          size == I2C_SMBUS_BLOCK_PROC_CALL_PEC)) {
            if(i2c_smbus_check_pec(addr, command, size, partial, data))
                  return -1;
      }
      return res;
}


/* Next four are needed by i2c-isa */
EXPORT_SYMBOL_GPL(i2c_adapter_dev_release);
EXPORT_SYMBOL_GPL(i2c_adapter_driver);
EXPORT_SYMBOL_GPL(i2c_adapter_class);
EXPORT_SYMBOL_GPL(i2c_bus_type);

EXPORT_SYMBOL(i2c_add_adapter);
EXPORT_SYMBOL(i2c_del_adapter);
EXPORT_SYMBOL(i2c_add_driver);
EXPORT_SYMBOL(i2c_del_driver);
EXPORT_SYMBOL(i2c_attach_client);
EXPORT_SYMBOL(i2c_detach_client);
EXPORT_SYMBOL(i2c_use_client);
EXPORT_SYMBOL(i2c_release_client);
EXPORT_SYMBOL(i2c_clients_command);
EXPORT_SYMBOL(i2c_check_addr);

EXPORT_SYMBOL(i2c_master_send);
EXPORT_SYMBOL(i2c_master_recv);
EXPORT_SYMBOL(i2c_control);
EXPORT_SYMBOL(i2c_transfer);
EXPORT_SYMBOL(i2c_get_adapter);
EXPORT_SYMBOL(i2c_put_adapter);
EXPORT_SYMBOL(i2c_probe);

EXPORT_SYMBOL(i2c_smbus_xfer);
EXPORT_SYMBOL(i2c_smbus_write_quick);
EXPORT_SYMBOL(i2c_smbus_read_byte);
EXPORT_SYMBOL(i2c_smbus_write_byte);
EXPORT_SYMBOL(i2c_smbus_read_byte_data);
EXPORT_SYMBOL(i2c_smbus_write_byte_data);
EXPORT_SYMBOL(i2c_smbus_read_word_data);
EXPORT_SYMBOL(i2c_smbus_write_word_data);
EXPORT_SYMBOL(i2c_smbus_write_block_data);
EXPORT_SYMBOL(i2c_smbus_read_i2c_block_data);

MODULE_AUTHOR("Simon G. Vogl <simon@tk.uni-linz.ac.at>");
MODULE_DESCRIPTION("I2C-Bus main module");
MODULE_LICENSE("GPL");

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