/*
    i2c-dev.c - Part of lm_sensors, Linux kernel modules for hardware
                 monitoring
    Copyright (c) 1995-1997, 1999 by Frodo Looijaard <frodol@dds.nl> and
    Simon 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.
*/

/* Note that this is a complete rewrite of Simon Vogl's i2c-dev module.
   But I have used so much of his original code and ideas that it seems
   only fair to recognize him as co-author -- Frodo */

#include <linux/module.h>
#include <linux/fs.h>
#include <linux/malloc.h>
#include "compat.h"
#include "i2c.h"
#include "isa.h"
#include "sensors.h"
#include "version.h"

#ifdef MODULE
extern int init_module(void);
extern int cleanup_module(void);
#endif /* def MODULE */

/* struct file_operations changed too often in the 2.1 series for nice code */

#if (LINUX_VERSION_CODE >= KERNEL_VERSION(2,1,70))
static loff_t i2cdev_lseek (struct file *file, loff_t offset, int origin);
#elif (LINUX_VERSION_CODE >= KERNEL_VERSION(2,1,56))
static long long i2cdev_lseek (struct file *file, long long offset, int origin);
#elif (LINUX_VERSION_CODE >= KERNEL_VERSION(2,1,0))
static long long i2cdev_llseek (struct inode *inode, struct file *file, 
                                long long offset, int origin);
#else
static int i2cdev_lseek (struct inode *inode, struct file *file, off_t offset, 
                         int origin);
#endif

#if (LINUX_VERSION_CODE >= KERNEL_VERSION(2,1,70))
static ssize_t i2cdev_read (struct file *file, char *buf, size_t count, 
                            loff_t *offset);
static ssize_t i2cdev_write (struct file *file, const char *buf, size_t count, 
                             loff_t *offset);
#elif (LINUX_VERSION_CODE >= KERNEL_VERSION(2,1,0))
static long i2cdev_read (struct inode *inode, struct file *file, char *buf, 
                         unsigned long count);
static long i2cdev_write (struct inode *inode, struct file *file, 
                          const char *buf, unsigned long offset);
#else
static int i2cdev_read(struct inode *inode, struct file *file, char *buf, 
                       int count);
static int i2cdev_write(struct inode *inode, struct file *file, 
                        const char *buf, int count);
#endif

static int i2cdev_ioctl (struct inode *inode, struct file *file, 
                         unsigned int cmd, unsigned long arg);
static int i2cdev_open (struct inode *inode, struct file *file);

#if (LINUX_VERSION_CODE >= KERNEL_VERSION(2,1,31))
static int i2cdev_release (struct inode *inode, struct file *file);
#else
static void i2cdev_release (struct inode *inode, struct file *file);
#endif


static int i2cdev_attach_adapter(struct i2c_adapter *adap);
static int i2cdev_detach_client(struct i2c_client *client);
static int i2cdev_command(struct i2c_client *client, unsigned int cmd,
                           void *arg);
static void i2cdev_inc_use(struct i2c_client *client);
static void i2cdev_dec_use(struct i2c_client *client);

static int i2cdev_init(void);
static int i2cdev_cleanup(void);

static struct file_operations i2cdev_fops = {
    i2cdev_lseek,
    i2cdev_read,
    i2cdev_write,
    NULL,                   /* i2cdev_readdir  */
    NULL,                   /* i2cdev_select   */
    i2cdev_ioctl,
    NULL,                   /* i2cdev_mmap     */
    i2cdev_open,
#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,1,118)
    NULL,                   /* i2cdev_flush    */
#endif
    i2cdev_release,
};

#define I2CDEV_CLIENTS_MAX I2C_ADAP_MAX
static struct i2c_client *i2cdev_clients[I2CDEV_CLIENTS_MAX];

static struct i2c_driver i2cdev_driver = {
  /* name */            "i2c-dev dummy driver",
  /* id */              I2C_DRIVERID_I2CDEV,
  /* flags */           DF_NOTIFY,
  /* attach_adapter */  &i2cdev_attach_adapter,
  /* detach_client */   &i2cdev_detach_client,
  /* command */         &i2cdev_command,
  /* inc_use */         &i2cdev_inc_use,
  /* dec_use */         &i2cdev_dec_use
};

static struct i2c_client i2cdev_client_template = {
  /* name */          "I2C /dev entry",
  /* id */            1,
  /* flags */         0,
  /* addr */          -1,
  /* adapter */       NULL,
  /* driver */        &i2cdev_driver,
  /* data */          NULL
};

static int i2cdev_initialized;

/* Note that the lseek function is called llseek in 2.1 kernels. But things
   are complicated enough as is. */
#if (LINUX_VERSION_CODE >= KERNEL_VERSION(2,1,70))
loff_t i2cdev_lseek (struct file *file, loff_t offset, int origin)
#elif (LINUX_VERSION_CODE >= KERNEL_VERSION(2,1,56))
long long i2cdev_lseek (struct file *file, long long offset, int origin)
#elif (LINUX_VERSION_CODE >= KERNEL_VERSION(2,1,0))
long long i2cdev_llseek (struct inode *inode, struct file *file, 
                         long long offset, int origin)
#else
int i2cdev_lseek (struct inode *inode, struct file *file, off_t offset, 
                  int origin)
#endif
{
  return -ESPIPE;
}

#if (LINUX_VERSION_CODE >= KERNEL_VERSION(2,1,70))
static ssize_t i2cdev_read (struct file *file, char *buf, size_t count,
                            loff_t *offset)
#elif (LINUX_VERSION_CODE >= KERNEL_VERSION(2,1,0))
static long i2cdev_read (struct inode *inode, struct file *file, char *buf,
                         unsigned long count)
#else
static int i2cdev_read(struct inode *inode, struct file *file, char *buf,
                       int count)
#endif
{
  char *tmp;
  int ret;

  struct i2c_client *client = (struct i2c_client *)file->private_data;

#ifdef  DEBUG
  printk("i2cdev_read: i2c%d reading %d bytes from %d.\n",minor,count,
         client->addr);
#endif

  /* copy user space data to kernel space. */
  tmp = kmalloc(count,GFP_KERNEL);
  if (tmp==NULL)
     return -ENOMEM;
  ret = i2c_master_recv(client,tmp,count);
  copy_to_user(buf,tmp,count);
  kfree(tmp);
  return ret;
}

#if (LINUX_VERSION_CODE >= KERNEL_VERSION(2,1,70))
static ssize_t i2cdev_write (struct file *file, const char *buf, size_t count,
                             loff_t *offset)
#elif (LINUX_VERSION_CODE >= KERNEL_VERSION(2,1,0))
static long i2cdev_write (struct inode *inode, struct file *file,
                          const char *buf, unsigned long offset)
#else
static int i2cdev_write(struct inode *inode, struct file *file,
                        const char *buf, int count)
#endif
{
  int ret;
  char *tmp;
  struct i2c_client *client = (struct i2c_client *)file->private_data;

  /* copy user space data to kernel space. */
  tmp = kmalloc(count,GFP_KERNEL);
  if (tmp==NULL)
    return -ENOMEM;
  copy_from_user(tmp,buf,count);

#ifdef DEBUG
  printk("i2c_write: i2c%d writing %d bytes.\n",minor,count);
#endif
  ret = i2c_master_send(client,tmp,count);
  kfree(tmp);
  return ret;
}

  
int i2cdev_open (struct inode *inode, struct file *file)
{
  unsigned int minor = MINOR(inode->i_rdev);
  struct i2c_client *client;

  if (! i2cdev_clients[minor]) {
#ifdef DEBUG
    printk("i2cdev: trying to open unattached adapter i2c-%d\n",minor);
#endif
    return -ENODEV;
  }

  /* Note that we here allocate a client for later use, but we will *not*
     register this client! Yes, this is safe. No, it is not very clean. */
  if(! (client = kmalloc(sizeof(struct i2c_client),GFP_KERNEL)))
    return -ENOMEM;
  memcpy(client,&i2cdev_client_template,sizeof(struct i2c_client));
  client->adapter = i2cdev_clients[minor]->adapter;
  file->private_data = client;

  MOD_INC_USE_COUNT;

#ifdef DEBUG
  printk("i2cdev_open: i2c-%d\n",minor);
#endif
  return 0;
}

#if (LINUX_VERSION_CODE >= KERNEL_VERSION(2,1,31))
static int i2cdev_release (struct inode *inode, struct file *file)
#else
static void i2cdev_release (struct inode *inode, struct file *file)
#endif
{
   kfree(file->private_data);
   file->private_data=NULL;
#ifdef DEBUG
   printk("i2c_close: i2c-%d\n", MINOR(inode->i_rdev));
#endif
  MOD_DEC_USE_COUNT;
#if (LINUX_VERSION_CODE >= KERNEL_VERSION(2,1,31))
   return 0;
#endif
}

int i2cdev_attach_adapter(struct i2c_adapter *adap)
{
  int i,res;
  struct i2c_client *client;

  if ((i = i2c_adapter_id(adap)) < 0) {
    printk("i2cdev_attach_adapter: unknown adapter?!?\n");
    return -ENODEV;
  }
  if (i >= I2CDEV_CLIENTS_MAX) {
    printk("i2cdev_attach_adapter: adapter number too large?!? (%d)\n",i);
    return -ENODEV;
  }
  if (i2cdev_clients[i]) {
    printk("i2cdev_attach_adapter: adapter already in use?!? (%d)\n",i);
    return -EBUSY;
  }
  if (i2c_is_isa_adapter(adap)) {
    printk("i2cdev_attach_adapter: Can't open ISA adapter!\n");
    return -ENODEV;
  }

  if (! (client = (struct i2c_client *)kmalloc(sizeof(struct i2c_client), 
                                               GFP_KERNEL)))
    return -ENOMEM;
  memcpy(client,&i2cdev_client_template,sizeof(struct i2c_client));
  client->adapter = adap;
  if ((res =  i2c_attach_client(client))) {
    printk("i2cdev_attach_adapter: attaching client failed.\n");
    kfree(client);
    return res;
  }
  i2cdev_clients[i] = client;
  printk("i2cdev: registered '%s' as minor %d\n",adap->name,i);
  return 0;
}

int i2cdev_detach_client(struct i2c_client *client)
{
  struct i2c_adapter *adap = client->adapter;
  int i,res;

  if ((i = i2c_adapter_id(adap)) < 0) {
    printk("i2cdev_detach_adapter: unknown adapter?!?\n");
    return -ENODEV;
  }
  if (i >= I2CDEV_CLIENTS_MAX) {
    printk("i2cdev_detach_adapter: adapter number too large?!? (%d)\n",i);
    return -ENODEV;
  }
  if (!i2cdev_clients[i]) {
    printk("i2cdev_detach_adapter: adapter not in use?!? (%d)\n",i);
    return -ENODEV;
  }

  if ((res =  i2c_detach_client(client))) {
    printk("i2cdev_detach_adapter: detaching client failed.\n");
    return res;
  }

  kfree(i2cdev_clients[i]);
  i2cdev_clients[i] = NULL;

#ifdef DEBUG
  printk("i2c(char): adapter unregistered: %s\n",adap->name);
#endif
  return 0;
}

static int i2cdev_command(struct i2c_client *client, unsigned int cmd,
                           void *arg)
{
  return -1;
}


static void i2cdev_inc_use(struct i2c_client *client)
{
#ifdef MODULE
  MOD_INC_USE_COUNT;
#endif
}

static void i2cdev_dec_use(struct i2c_client *client)
{
#ifdef MODULE
  MOD_DEC_USE_COUNT;
#endif
}

int i2cdev_init(void)
{
  int res;

  printk("i2c-dev.o version %s (%s)\n",LM_VERSION,LM_DATE);
  i2cdev_initialized = 0;
  if (register_chrdev(I2C_MAJOR,"i2c",&i2cdev_fops)) {
    printk("i2c-dev.o: unable to get major %d for i2c bus\n",I2C_MAJOR);
    return -EIO;
  }
  i2cdev_initialized ++;

  if ((res = i2c_add_driver(&i2cdev_driver))) {
    printk("i2c-dev.o: Driver registration failed, module not inserted.\n");
    i2cdev_cleanup();
    return res;
  }
  i2cdev_initialized ++;
  return 0;
}

int i2cdev_cleanup(void)
{
  int res;

  if (i2cdev_initialized >= 2) {
    if ((res = i2c_del_driver(&i2cdev_driver))) {
      printk("i2c-dev.o: Driver deregistration failed, "
             "module not removed.\n");
      return res;
    }
    i2cdev_initialized ++;
  }

  if (i2cdev_initialized >= 1) {
    if ((res = unregister_chrdev(I2C_MAJOR,"i2c"))) {
      printk("i2c-dev.o: unable to release major %d for i2c bus\n",I2C_MAJOR);
      return res;
    }
    i2cdev_initialized --;
  }
  return 0;
}


#ifdef MODULE

MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl> and Simon G. Vogl <simon@tk.uni-linz.ac.at>");
MODULE_DESCRIPTION("I2C /dev entries driver");

int init_module(void)
{
  return i2cdev_init();
}

int cleanup_module(void)
{
  return i2cdev_cleanup();
}

#endif /* def MODULE */