/*
   * 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
   *
   * Copyright (C) IBM Corp. 2006
   *
   * Authors: Hollis Blanchard <hollisb@us.ibm.com>
   */

  #include <linux/mm.h>

  #include <linux/slab.h>

  #include <asm/page.h>
  #include <xen/xencomm.h>
  #include <xen/interface/xen.h>

  #include <asm/xen/xencomm.h>	/* for xencomm_is_phys_contiguous() */

  
  static int xencomm_init(struct xencomm_desc *desc,
  			void *buffer, unsigned long bytes)
  {
  	unsigned long recorded = 0;
  	int i = 0;
  
  	while ((recorded < bytes) && (i < desc->nr_addrs)) {
  		unsigned long vaddr = (unsigned long)buffer + recorded;
  		unsigned long paddr;
  		int offset;
  		int chunksz;
  
  		offset = vaddr % PAGE_SIZE; /* handle partial pages */
  		chunksz = min(PAGE_SIZE - offset, bytes - recorded);
  
  		paddr = xencomm_vtop(vaddr);
  		if (paddr == ~0UL) {
  			printk(KERN_DEBUG "%s: couldn't translate vaddr %lx
  ",
  			       __func__, vaddr);
  			return -EINVAL;
  		}
  
  		desc->address[i++] = paddr;
  		recorded += chunksz;
  	}
  
  	if (recorded < bytes) {
  		printk(KERN_DEBUG
  		       "%s: could only translate %ld of %ld bytes
  ",
  		       __func__, recorded, bytes);
  		return -ENOSPC;
  	}
  
  	/* mark remaining addresses invalid (just for safety) */
  	while (i < desc->nr_addrs)
  		desc->address[i++] = XENCOMM_INVALID;
  
  	desc->magic = XENCOMM_MAGIC;
  
  	return 0;
  }
  
  static struct xencomm_desc *xencomm_alloc(gfp_t gfp_mask,
  					  void *buffer, unsigned long bytes)
  {
  	struct xencomm_desc *desc;
  	unsigned long buffer_ulong = (unsigned long)buffer;
  	unsigned long start = buffer_ulong & PAGE_MASK;
  	unsigned long end = (buffer_ulong + bytes) | ~PAGE_MASK;
  	unsigned long nr_addrs = (end - start + 1) >> PAGE_SHIFT;
  	unsigned long size = sizeof(*desc) +
  		sizeof(desc->address[0]) * nr_addrs;
  
  	/*
  	 * slab allocator returns at least sizeof(void*) aligned pointer.
  	 * When sizeof(*desc) > sizeof(void*), struct xencomm_desc might
  	 * cross page boundary.
  	 */
  	if (sizeof(*desc) > sizeof(void *)) {
  		unsigned long order = get_order(size);
  		desc = (struct xencomm_desc *)__get_free_pages(gfp_mask,
  							       order);
  		if (desc == NULL)
  			return NULL;
  
  		desc->nr_addrs =
  			((PAGE_SIZE << order) - sizeof(struct xencomm_desc)) /
  			sizeof(*desc->address);
  	} else {
  		desc = kmalloc(size, gfp_mask);
  		if (desc == NULL)
  			return NULL;
  
  		desc->nr_addrs = nr_addrs;
  	}
  	return desc;
  }
  
  void xencomm_free(struct xencomm_handle *desc)
  {
  	if (desc && !((ulong)desc & XENCOMM_INLINE_FLAG)) {
  		struct xencomm_desc *desc__ = (struct xencomm_desc *)desc;
  		if (sizeof(*desc__) > sizeof(void *)) {
  			unsigned long size = sizeof(*desc__) +
  				sizeof(desc__->address[0]) * desc__->nr_addrs;
  			unsigned long order = get_order(size);
  			free_pages((unsigned long)__va(desc), order);
  		} else
  			kfree(__va(desc));
  	}
  }
  
  static int xencomm_create(void *buffer, unsigned long bytes,
  			  struct xencomm_desc **ret, gfp_t gfp_mask)
  {
  	struct xencomm_desc *desc;
  	int rc;
  
  	pr_debug("%s: %p[%ld]
  ", __func__, buffer, bytes);
  
  	if (bytes == 0) {
  		/* don't create a descriptor; Xen recognizes NULL. */
  		BUG_ON(buffer != NULL);
  		*ret = NULL;
  		return 0;
  	}
  
  	BUG_ON(buffer == NULL); /* 'bytes' is non-zero */
  
  	desc = xencomm_alloc(gfp_mask, buffer, bytes);
  	if (!desc) {
  		printk(KERN_DEBUG "%s failure
  ", "xencomm_alloc");
  		return -ENOMEM;
  	}
  
  	rc = xencomm_init(desc, buffer, bytes);
  	if (rc) {
  		printk(KERN_DEBUG "%s failure: %d
  ", "xencomm_init", rc);
  		xencomm_free((struct xencomm_handle *)__pa(desc));
  		return rc;
  	}
  
  	*ret = desc;
  	return 0;
  }

  static struct xencomm_handle *xencomm_create_inline(void *ptr)
  {
  	unsigned long paddr;

  	BUG_ON(!xencomm_is_phys_contiguous((unsigned long)ptr));

  
  	paddr = (unsigned long)xencomm_pa(ptr);
  	BUG_ON(paddr & XENCOMM_INLINE_FLAG);
  	return (struct xencomm_handle *)(paddr | XENCOMM_INLINE_FLAG);
  }
  
  /* "mini" routine, for stack-based communications: */
  static int xencomm_create_mini(void *buffer,
  	unsigned long bytes, struct xencomm_mini *xc_desc,
  	struct xencomm_desc **ret)
  {
  	int rc = 0;
  	struct xencomm_desc *desc;
  	BUG_ON(((unsigned long)xc_desc) % sizeof(*xc_desc) != 0);
  
  	desc = (void *)xc_desc;
  
  	desc->nr_addrs = XENCOMM_MINI_ADDRS;
  
  	rc = xencomm_init(desc, buffer, bytes);
  	if (!rc)
  		*ret = desc;
  
  	return rc;
  }
  
  struct xencomm_handle *xencomm_map(void *ptr, unsigned long bytes)
  {
  	int rc;
  	struct xencomm_desc *desc;

  	if (xencomm_is_phys_contiguous((unsigned long)ptr))

  		return xencomm_create_inline(ptr);
  
  	rc = xencomm_create(ptr, bytes, &desc, GFP_KERNEL);
  
  	if (rc || desc == NULL)
  		return NULL;
  
  	return xencomm_pa(desc);
  }
  
  struct xencomm_handle *__xencomm_map_no_alloc(void *ptr, unsigned long bytes,
  			struct xencomm_mini *xc_desc)
  {
  	int rc;
  	struct xencomm_desc *desc = NULL;

  	if (xencomm_is_phys_contiguous((unsigned long)ptr))

  		return xencomm_create_inline(ptr);
  
  	rc = xencomm_create_mini(ptr, bytes, xc_desc,
  				&desc);
  
  	if (rc)
  		return NULL;
  
  	return xencomm_pa(desc);
  }