text: /*
   * arch/xtensa/platforms/iss/simdisk.c
   *
   * This file is subject to the terms and conditions of the GNU General Public
   * License.  See the file "COPYING" in the main directory of this archive
   * for more details.
   *
   * Copyright (C) 2001-2013 Tensilica Inc.
   *   Authors	Victor Prupis
   */
  
  #include <linux/module.h>
  #include <linux/moduleparam.h>
  #include <linux/kernel.h>
  #include <linux/init.h>
  #include <linux/string.h>
  #include <linux/blkdev.h>
  #include <linux/bio.h>
  #include <linux/proc_fs.h>
  #include <linux/uaccess.h>
  #include <platform/simcall.h>
  
  #define SIMDISK_MAJOR 240
  #define SIMDISK_MINORS 1
  #define MAX_SIMDISK_COUNT 10
  
  struct simdisk {
  	const char *filename;
  	spinlock_t lock;
  	struct gendisk *gd;
  	struct proc_dir_entry *procfile;
  	int users;
  	unsigned long size;
  	int fd;
  };
  
  
  static int simdisk_count = CONFIG_BLK_DEV_SIMDISK_COUNT;
  module_param(simdisk_count, int, S_IRUGO);
  MODULE_PARM_DESC(simdisk_count, "Number of simdisk units.");
  
  static int n_files;
  static const char *filename[MAX_SIMDISK_COUNT] = {
  #ifdef CONFIG_SIMDISK0_FILENAME
  	CONFIG_SIMDISK0_FILENAME,
  #ifdef CONFIG_SIMDISK1_FILENAME
  	CONFIG_SIMDISK1_FILENAME,
  #endif
  #endif
  };
  
  static int simdisk_param_set_filename(const char *val,
  		const struct kernel_param *kp)
  {
  	if (n_files < ARRAY_SIZE(filename))
  		filename[n_files++] = val;
  	else
  		return -EINVAL;
  	return 0;
  }
  
  static const struct kernel_param_ops simdisk_param_ops_filename = {
  	.set = simdisk_param_set_filename,
  };
  module_param_cb(filename, &simdisk_param_ops_filename, &n_files, 0);
  MODULE_PARM_DESC(filename, "Backing storage filename.");
  
  static int simdisk_major = SIMDISK_MAJOR;
  
  static void simdisk_transfer(struct simdisk *dev, unsigned long sector,
  		unsigned long nsect, char *buffer, int write)
  {
  	unsigned long offset = sector << SECTOR_SHIFT;
  	unsigned long nbytes = nsect << SECTOR_SHIFT;
  
  	if (offset > dev->size || dev->size - offset < nbytes) {
  		pr_notice("Beyond-end %s (%ld %ld)\n",
  				write ? "write" : "read", offset, nbytes);
  		return;
  	}
  
  	spin_lock(&dev->lock);
  	while (nbytes > 0) {
  		unsigned long io;
  
  		simc_lseek(dev->fd, offset, SEEK_SET);
  		READ_ONCE(*buffer);
  		if (write)
  			io = simc_write(dev->fd, buffer, nbytes);
  		else
  			io = simc_read(dev->fd, buffer, nbytes);
  		if (io == -1) {
  			pr_err("SIMDISK: IO error %d\n", errno);
  			break;
  		}
  		buffer += io;
  		offset += io;
  		nbytes -= io;
  	}
  	spin_unlock(&dev->lock);
  }
  
  static void simdisk_submit_bio(struct bio *bio)
  {
  	struct simdisk *dev = bio->bi_bdev->bd_disk->private_data;
  	struct bio_vec bvec;
  	struct bvec_iter iter;
  	sector_t sector = bio->bi_iter.bi_sector;
  
  	bio_for_each_segment(bvec, bio, iter) {
  		char *buffer = bvec_kmap_local(&bvec);
  		unsigned len = bvec.bv_len >> SECTOR_SHIFT;
  
  		simdisk_transfer(dev, sector, len, buffer,
  				bio_data_dir(bio) == WRITE);
  		sector += len;
  		kunmap_local(buffer);
  	}
  
  	bio_endio(bio);
  }
  
  static int simdisk_open(struct block_device *bdev, fmode_t mode)
  {
  	struct simdisk *dev = bdev->bd_disk->private_data;
  
  	spin_lock(&dev->lock);
  	++dev->users;
  	spin_unlock(&dev->lock);
  	return 0;
  }
  
  static void simdisk_release(struct gendisk *disk, fmode_t mode)
  {
  	struct simdisk *dev = disk->private_data;
  	spin_lock(&dev->lock);
  	--dev->users;
  	spin_unlock(&dev->lock);
  }
  
  static const struct block_device_operations simdisk_ops = {
  	.owner		= THIS_MODULE,
  	.submit_bio	= simdisk_submit_bio,
  	.open		= simdisk_open,
  	.release	= simdisk_release,
  };
  
  static struct simdisk *sddev;
  static struct proc_dir_entry *simdisk_procdir;
  
  static int simdisk_attach(struct simdisk *dev, const char *filename)
  {
  	int err = 0;
  
  	filename = kstrdup(filename, GFP_KERNEL);
  	if (filename == NULL)
  		return -ENOMEM;
  
  	spin_lock(&dev->lock);
  
  	if (dev->fd != -1) {
  		err = -EBUSY;
  		goto out;
  	}
  	dev->fd = simc_open(filename, O_RDWR, 0);
  	if (dev->fd == -1) {
  		pr_err("SIMDISK: Can't open %s: %d\n", filename, errno);
  		err = -ENODEV;
  		goto out;
  	}
  	dev->size = simc_lseek(dev->fd, 0, SEEK_END);
  	set_capacity(dev->gd, dev->size >> SECTOR_SHIFT);
  	dev->filename = filename;
  	pr_info("SIMDISK: %s=%s\n", dev->gd->disk_name, dev->filename);
  out:
  	if (err)
  		kfree(filename);
  	spin_unlock(&dev->lock);
  
  	return err;
  }
  
  static int simdisk_detach(struct simdisk *dev)
  {
  	int err = 0;
  
  	spin_lock(&dev->lock);
  
  	if (dev->users != 0) {
  		err = -EBUSY;
  	} else if (dev->fd != -1) {
  		if (simc_close(dev->fd)) {
  			pr_err("SIMDISK: error closing %s: %d\n",
  					dev->filename, errno);
  			err = -EIO;
  		} else {
  			pr_info("SIMDISK: %s detached from %s\n",
  					dev->gd->disk_name, dev->filename);
  			dev->fd = -1;
  			kfree(dev->filename);
  			dev->filename = NULL;
  		}
  	}
  	spin_unlock(&dev->lock);
  	return err;
  }
  
  static ssize_t proc_read_simdisk(struct file *file, char __user *buf,
  			size_t size, loff_t *ppos)
  {
  	struct simdisk *dev = pde_data(file_inode(file));
  	const char *s = dev->filename;
  	if (s) {
  		ssize_t n = simple_read_from_buffer(buf, size, ppos,
  							s, strlen(s));
  		if (n < 0)
  			return n;
  		buf += n;
  		size -= n;
  	}
  	return simple_read_from_buffer(buf, size, ppos, "\n", 1);
  }
  
  static ssize_t proc_write_simdisk(struct file *file, const char __user *buf,
  			size_t count, loff_t *ppos)
  {
  	char *tmp = memdup_user_nul(buf, count);
  	struct simdisk *dev = pde_data(file_inode(file));
  	int err;
  
  	if (IS_ERR(tmp))
  		return PTR_ERR(tmp);
  
  	err = simdisk_detach(dev);
  	if (err != 0)
  		goto out_free;
  
  	if (count > 0 && tmp[count - 1] == '\n')
  		tmp[count - 1] = 0;
  
  	if (tmp[0])
  		err = simdisk_attach(dev, tmp);
  
  	if (err == 0)
  		err = count;
  out_free:
  	kfree(tmp);
  	return err;
  }
  
  static const struct proc_ops simdisk_proc_ops = {
  	.proc_read	= proc_read_simdisk,
  	.proc_write	= proc_write_simdisk,
  	.proc_lseek	= default_llseek,
  };
  
  static int __init simdisk_setup(struct simdisk *dev, int which,
  		struct proc_dir_entry *procdir)
  {
  	char tmp[2] = { '0' + which, 0 };
  	int err = -ENOMEM;
  
  	dev->fd = -1;
  	dev->filename = NULL;
  	spin_lock_init(&dev->lock);
  	dev->users = 0;
  
  	dev->gd = blk_alloc_disk(NUMA_NO_NODE);
  	if (!dev->gd)
  		goto out;
  	dev->gd->major = simdisk_major;
  	dev->gd->first_minor = which;
  	dev->gd->minors = SIMDISK_MINORS;
  	dev->gd->fops = &simdisk_ops;
  	dev->gd->private_data = dev;
  	snprintf(dev->gd->disk_name, 32, "simdisk%d", which);
  	set_capacity(dev->gd, 0);
  	err = add_disk(dev->gd);
  	if (err)
  		goto out_cleanup_disk;
  
  	dev->procfile = proc_create_data(tmp, 0644, procdir, &simdisk_proc_ops, dev);
  
  	return 0;
  
  out_cleanup_disk:
  	blk_cleanup_disk(dev->gd);
  out:
  	return err;
  }
  
  static int __init simdisk_init(void)
  {
  	int i;
  
  	if (register_blkdev(simdisk_major, "simdisk") < 0) {
  		pr_err("SIMDISK: register_blkdev: %d\n", simdisk_major);
  		return -EIO;
  	}
  	pr_info("SIMDISK: major: %d\n", simdisk_major);
  
  	if (n_files > simdisk_count)
  		simdisk_count = n_files;
  	if (simdisk_count > MAX_SIMDISK_COUNT)
  		simdisk_count = MAX_SIMDISK_COUNT;
  
  	sddev = kmalloc_array(simdisk_count, sizeof(*sddev), GFP_KERNEL);
  	if (sddev == NULL)
  		goto out_unregister;
  
  	simdisk_procdir = proc_mkdir("simdisk", 0);
  	if (simdisk_procdir == NULL)
  		goto out_free_unregister;
  
  	for (i = 0; i < simdisk_count; ++i) {
  		if (simdisk_setup(sddev + i, i, simdisk_procdir) == 0) {
  			if (filename[i] != NULL && filename[i][0] != 0 &&
  					(n_files == 0 || i < n_files))
  				simdisk_attach(sddev + i, filename[i]);
  		}
  	}
  
  	return 0;
  
  out_free_unregister:
  	kfree(sddev);
  out_unregister:
  	unregister_blkdev(simdisk_major, "simdisk");
  	return -ENOMEM;
  }
  module_init(simdisk_init);
  
  static void simdisk_teardown(struct simdisk *dev, int which,
  		struct proc_dir_entry *procdir)
  {
  	char tmp[2] = { '0' + which, 0 };
  
  	simdisk_detach(dev);
  	if (dev->gd) {
  		del_gendisk(dev->gd);
  		blk_cleanup_disk(dev->gd);
  	}
  	remove_proc_entry(tmp, procdir);
  }
  
  static void __exit simdisk_exit(void)
  {
  	int i;
  
  	for (i = 0; i < simdisk_count; ++i)
  		simdisk_teardown(sddev + i, i, simdisk_procdir);
  	remove_proc_entry("simdisk", 0);
  	kfree(sddev);
  	unregister_blkdev(simdisk_major, "simdisk");
  }
  module_exit(simdisk_exit);
  
  MODULE_ALIAS_BLOCKDEV_MAJOR(SIMDISK_MAJOR);
  
  MODULE_LICENSE("GPL");
  