/*
   * Copyright (C) 2012 CERN (www.cern.ch)
   * Author: Alessandro Rubini <rubini@gnudd.com>
   *
   * Released according to the GNU GPL, version 2 or any later version.
   *
   * This work is part of the White Rabbit project, a research effort led
   * by CERN, the European Institute for Nuclear Research.
   */
  #include <linux/module.h>
  #include <linux/init.h>
  #include <linux/list.h>
  #include <linux/slab.h>
  #include <linux/fs.h>
  #include <linux/miscdevice.h>
  #include <linux/spinlock.h>
  #include <linux/fmc.h>
  #include <linux/uaccess.h>
  
  static LIST_HEAD(fc_devices);
  static DEFINE_SPINLOCK(fc_lock);
  
  struct fc_instance {
  	struct list_head list;
  	struct fmc_device *fmc;
  	struct miscdevice misc;
  };
  
  /* at open time, we must identify our device */
  static int fc_open(struct inode *ino, struct file *f)
  {
  	struct fmc_device *fmc;
  	struct fc_instance *fc;
  	int minor = iminor(ino);
  
  	list_for_each_entry(fc, &fc_devices, list)
  		if (fc->misc.minor == minor)
  			break;
  	if (fc->misc.minor != minor)
  		return -ENODEV;
  	fmc = fc->fmc;
  	if (try_module_get(fmc->owner) == 0)
  		return -ENODEV;
  
  	f->private_data = fmc;
  	return 0;
  }
  
  static int fc_release(struct inode *ino, struct file *f)
  {
  	struct fmc_device *fmc = f->private_data;
  	module_put(fmc->owner);
  	return 0;
  }
  
  /* read and write are simple after the default llseek has been used */
  static ssize_t fc_read(struct file *f, char __user *buf, size_t count,
  		       loff_t *offp)
  {
  	struct fmc_device *fmc = f->private_data;
  	unsigned long addr;
  	uint32_t val;
  
  	if (count < sizeof(val))
  		return -EINVAL;
  	count = sizeof(val);
  
  	addr = *offp;
  	if (addr > fmc->memlen)
  		return -ESPIPE; /* Illegal seek */
  	val = fmc_readl(fmc, addr);
  	if (copy_to_user(buf, &val, count))
  		return -EFAULT;
  	*offp += count;
  	return count;
  }
  
  static ssize_t fc_write(struct file *f, const char __user *buf, size_t count,
  			loff_t *offp)
  {
  	struct fmc_device *fmc = f->private_data;
  	unsigned long addr;
  	uint32_t val;
  
  	if (count < sizeof(val))
  		return -EINVAL;
  	count = sizeof(val);
  
  	addr = *offp;
  	if (addr > fmc->memlen)
  		return -ESPIPE; /* Illegal seek */
  	if (copy_from_user(&val, buf, count))
  		return -EFAULT;
  	fmc_writel(fmc, val, addr);
  	*offp += count;
  	return count;
  }
  
  static const struct file_operations fc_fops = {
  	.owner = THIS_MODULE,
  	.open = fc_open,
  	.release = fc_release,
  	.llseek = generic_file_llseek,
  	.read = fc_read,
  	.write = fc_write,
  };
  
  
  /* Device part .. */
  static int fc_probe(struct fmc_device *fmc);
  static int fc_remove(struct fmc_device *fmc);
  
  static struct fmc_driver fc_drv = {
  	.version = FMC_VERSION,
  	.driver.name = KBUILD_MODNAME,
  	.probe = fc_probe,
  	.remove = fc_remove,
  	/* no table: we want to match everything */
  };
  
  /* We accept the generic busid parameter */
  FMC_PARAM_BUSID(fc_drv);
  
  /* probe and remove must allocate and release a misc device */
  static int fc_probe(struct fmc_device *fmc)
  {
  	int ret;
  	int index = 0;
  
  	struct fc_instance *fc;
  
  	if (fmc->op->validate)
  		index = fmc->op->validate(fmc, &fc_drv);
  	if (index < 0)
  		return -EINVAL; /* not our device: invalid */
  
  	/* Create a char device: we want to create it anew */
  	fc = kzalloc(sizeof(*fc), GFP_KERNEL);
  	if (!fc)
  		return -ENOMEM;
  	fc->fmc = fmc;
  	fc->misc.minor = MISC_DYNAMIC_MINOR;
  	fc->misc.fops = &fc_fops;
  	fc->misc.name = kstrdup(dev_name(&fmc->dev), GFP_KERNEL);
  
  	ret = misc_register(&fc->misc);
  	if (ret < 0)
  		goto out;
  	spin_lock(&fc_lock);
  	list_add(&fc->list, &fc_devices);
  	spin_unlock(&fc_lock);
  	dev_info(&fc->fmc->dev, "Created misc device \"%s\"
  ",
  		 fc->misc.name);
  	return 0;
  
  out:
  	kfree(fc->misc.name);
  	kfree(fc);
  	return ret;
  }
  
  static int fc_remove(struct fmc_device *fmc)
  {
  	struct fc_instance *fc;
  
  	list_for_each_entry(fc, &fc_devices, list)
  		if (fc->fmc == fmc)
  			break;
  	if (fc->fmc != fmc) {
  		dev_err(&fmc->dev, "remove called but not found
  ");
  		return -ENODEV;
  	}
  
  	spin_lock(&fc_lock);
  	list_del(&fc->list);
  	spin_unlock(&fc_lock);
  	misc_deregister(&fc->misc);
  	kfree(fc->misc.name);
  	kfree(fc);
  
  	return 0;
  }
  
  
  static int fc_init(void)
  {
  	int ret;
  
  	ret = fmc_driver_register(&fc_drv);
  	return ret;
  }
  
  static void fc_exit(void)
  {
  	fmc_driver_unregister(&fc_drv);
  }
  
  module_init(fc_init);
  module_exit(fc_exit);
  
  MODULE_LICENSE("GPL");