[PATCH] I2C: Remove redundancy from i2c-core.c

[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / drivers / i2c / i2c-core.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);

/* match always succeeds, as we want the probe() to tell if we really accept this match */
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;
}

static 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;
}

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

static 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);
}

static 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, NULL, &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);

        /* 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);
        }

        dev_dbg(&adap->dev, "registered as adapter #%d\n", adap->nr);

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: Attempting to delete an unregistered "
                         "adapter\n");
                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_warn(&adap->dev, "can't detach adapter "
                                         "while detaching driver %s: driver not "
                                         "detached!", driver->name);
                                goto out_unlock;
                        }
        }

        /* detach any active clients. This must be done first, because
         * it can fail; in which case we give upp. */
        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, "adapter not "
                                "unregistered, because client at "
                                "address %02x can't be detached. ",
                                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 unregistered\n");

 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.
         */
        pr_debug("i2c-core: unregister_driver - looking for clients.\n");
        /* 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);
                dev_dbg(&adap->dev, "examining adapter\n");
                if (driver->detach_adapter) {
                        if ((res = driver->detach_adapter(adap))) {
                                dev_warn(&adap->dev, "while unregistering "
                                       "dummy driver %s, adapter could "
                                       "not be detached properly; driver "
                                       "not unloaded!",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;
                                pr_debug("i2c-core.o: detaching client %s:\n", client->name);
                                if ((res = driver->detach_client(client))) {
                                        dev_err(&adap->dev, "while "
                                                "unregistering driver "
                                                "`%s', the client at "
                                                "address %02x of "
                                                "adapter could not "
                                                "be detached; driver "
                                                "not unloaded!",
                                                driver->name,
                                                client->addr);
                                        goto out_unlock;
                                }
                        }
                }
        }

        driver_unregister(&driver->driver);
        list_del(&driver->list);
        pr_debug("i2c-core: driver unregistered: %s\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_warn(&adapter->dev, "warning: client_register "
                                "seems to have failed for client %02x\n",
                                client->addr);
                }
        }

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

        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);
        pr_debug("registering %s\n", 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))
                return -EBUSY;

        if (adapter->client_unregister)  {
                res = adapter->client_unregister(client);
                if (res) {
                        dev_err(&client->dev,
                               "client_unregister [%s] failed, "
                               "client not detached", 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!
 * ----------------------------------------------------
 */
int i2c_probe(struct i2c_adapter *adapter,
              struct i2c_client_address_data *address_data,
              int (*found_proc) (struct i2c_adapter *, int, int))
{
        int addr,i,found,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;

        for (addr = 0x00; addr <= 0x7f; addr++) {

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

                /* If it is in one of the force entries, we don't do any detection
                   at all */
                found = 0;

                for (i = 0; !found && (address_data->force[i] != I2C_CLIENT_END); i += 2) {
                        if (((adap_id == address_data->force[i]) || 
                             (address_data->force[i] == ANY_I2C_BUS)) &&
                             (addr == address_data->force[i+1])) {
                                dev_dbg(&adapter->dev, "found force parameter for adapter %d, addr %04x\n",
                                        adap_id, addr);
                                if ((err = found_proc(adapter,addr,0)))
                                        return err;
                                found = 1;
                        }
                }
                if (found) 
                        continue;

                /* If this address is in one of the ignores, we can forget about
                   it right now */
                for (i = 0;
                     !found && (address_data->ignore[i] != I2C_CLIENT_END);
                     i += 2) {
                        if (((adap_id == address_data->ignore[i]) || 
                            ((address_data->ignore[i] == ANY_I2C_BUS))) &&
                            (addr == address_data->ignore[i+1])) {
                                dev_dbg(&adapter->dev, "found ignore parameter for adapter %d, "
                                        "addr %04x\n", adap_id ,addr);
                                found = 1;
                        }
                }
                if (found) 
                        continue;

                /* Now, we will do a detection, but only if it is in the normal or 
                   probe entries */  
                for (i = 0;
                     !found && (address_data->normal_i2c[i] != I2C_CLIENT_END);
                     i += 1) {
                        if (addr == address_data->normal_i2c[i]) {
                                found = 1;
                                dev_dbg(&adapter->dev, "found normal i2c entry for adapter %d, "
                                        "addr %02x\n", adap_id, addr);
                        }
                }

                for (i = 0;
                     !found && (address_data->probe[i] != I2C_CLIENT_END);
                     i += 2) {
                        if (((adap_id == address_data->probe[i]) ||
                            ((address_data->probe[i] == ANY_I2C_BUS))) &&
                            (addr == address_data->probe[i+1])) {
                                found = 1;
                                dev_dbg(&adapter->dev, "found probe parameter for adapter %d, "
                                        "addr %04x\n", adap_id,addr);
                        }
                }
                if (!found) 
                        continue;

                /* OK, so we really should examine this address. First check
                   whether there is some client here at all! */
                if (i2c_smbus_xfer(adapter,addr,0,0,0,I2C_SMBUS_QUICK,NULL) >= 0)
                        if ((err = found_proc(adapter,addr,-1)))
                                return err;
        }
        return 0;
}

/*
 * return id number for a specific adapter
 */
int i2c_adapter_id(struct i2c_adapter *adap)
{
        return adap->nr;
}

struct i2c_adapter* i2c_get_adapter(int id)
{
        struct list_head   *item;
        struct i2c_adapter *adapter;
        
        down(&core_lists);
        list_for_each(item,&adapters) {
                adapter = list_entry(item, struct i2c_adapter, list);
                if (id == adapter->nr &&
                    try_module_get(adapter->owner)) {
                        up(&core_lists);
                        return adapter;
                }
        }
        up(&core_lists);
        return NULL;
}

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;
}


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_adapter_id);
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");