/*
   * helper functions for vmalloc video4linux capture buffers
   *

   * The functions expect the hardware being able to scatter gather

   * (i.e. the buffers are not linear in physical memory, but fragmented
   * into PAGE_SIZE chunks).  They also assume the driver does not need
   * to touch the video data.
   *
   * (c) 2007 Mauro Carvalho Chehab, <mchehab@infradead.org>
   *
   * 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
   */
  
  #include <linux/init.h>
  #include <linux/module.h>
  #include <linux/moduleparam.h>
  #include <linux/slab.h>
  #include <linux/interrupt.h>
  
  #include <linux/pci.h>
  #include <linux/vmalloc.h>
  #include <linux/pagemap.h>
  #include <asm/page.h>
  #include <asm/pgtable.h>
  
  #include <media/videobuf-vmalloc.h>
  
  #define MAGIC_DMABUF   0x17760309
  #define MAGIC_VMAL_MEM 0x18221223

  #define MAGIC_CHECK(is, should)						\
  	if (unlikely((is) != (should))) {				\
  		printk(KERN_ERR "magic mismatch: %x (expected %x)
  ",	\
  				is, should);				\
  		BUG();							\
  	}

  static int debug;

  module_param(debug, int, 0644);
  
  MODULE_DESCRIPTION("helper module to manage video4linux vmalloc buffers");
  MODULE_AUTHOR("Mauro Carvalho Chehab <mchehab@infradead.org>");
  MODULE_LICENSE("GPL");

  #define dprintk(level, fmt, arg...)					\
  	if (debug >= level)						\
  		printk(KERN_DEBUG "vbuf-vmalloc: " fmt , ## arg)

  
  
  /***************************************************************************/

  static void videobuf_vm_open(struct vm_area_struct *vma)

  {
  	struct videobuf_mapping *map = vma->vm_private_data;

  	dprintk(2, "vm_open %p [count=%u,vma=%08lx-%08lx]
  ", map,
  		map->count, vma->vm_start, vma->vm_end);

  
  	map->count++;
  }

  static void videobuf_vm_close(struct vm_area_struct *vma)

  {
  	struct videobuf_mapping *map = vma->vm_private_data;
  	struct videobuf_queue *q = map->q;

  	int i;

  	dprintk(2, "vm_close %p [count=%u,vma=%08lx-%08lx]
  ", map,

  		map->count, vma->vm_start, vma->vm_end);

  
  	map->count--;
  	if (0 == map->count) {

  		struct videobuf_vmalloc_memory *mem;
  
  		dprintk(1, "munmap %p q=%p
  ", map, q);

  		videobuf_queue_lock(q);

  
  		/* We need first to cancel streams, before unmapping */
  		if (q->streaming)
  			videobuf_queue_cancel(q);

  		for (i = 0; i < VIDEO_MAX_FRAME; i++) {
  			if (NULL == q->bufs[i])
  				continue;

  			if (q->bufs[i]->map != map)

  				continue;

  			mem = q->bufs[i]->priv;
  			if (mem) {
  				/* This callback is called only if kernel has
  				   allocated memory and this memory is mmapped.
  				   In this case, memory should be freed,
  				   in order to do memory unmap.
  				 */

  				MAGIC_CHECK(mem->magic, MAGIC_VMAL_MEM);

  
  				/* vfree is not atomic - can't be
  				   called with IRQ's disabled
  				 */
  				dprintk(1, "%s: buf[%d] freeing (%p)
  ",

  					__func__, i, mem->vaddr);

  				vfree(mem->vaddr);
  				mem->vaddr = NULL;

  			}

  			q->bufs[i]->map   = NULL;

  			q->bufs[i]->baddr = 0;

  		}

  		kfree(map);

  		videobuf_queue_unlock(q);

  	}

  	return;
  }

  static const struct vm_operations_struct videobuf_vm_ops = {

  	.open     = videobuf_vm_open,
  	.close    = videobuf_vm_close,
  };
  
  /* ---------------------------------------------------------------------
   * vmalloc handlers for the generic methods
   */
  
  /* Allocated area consists on 3 parts:
  	struct video_buffer
  	struct <driver>_buffer (cx88_buffer, saa7134_buf, ...)

  	struct videobuf_dma_sg_memory

   */

  static struct videobuf_buffer *__videobuf_alloc_vb(size_t size)

  {

  	struct videobuf_vmalloc_memory *mem;

  	struct videobuf_buffer *vb;

  	vb = kzalloc(size + sizeof(*mem), GFP_KERNEL);

  	if (!vb)
  		return vb;

  	mem = vb->priv = ((char *)vb) + size;
  	mem->magic = MAGIC_VMAL_MEM;

  	dprintk(1, "%s: allocated at %p(%ld+%ld) & %p(%ld)
  ",
  		__func__, vb, (long)sizeof(*vb), (long)size - sizeof(*vb),
  		mem, (long)sizeof(*mem));

  
  	return vb;
  }

  static int __videobuf_iolock(struct videobuf_queue *q,
  			     struct videobuf_buffer *vb,
  			     struct v4l2_framebuffer *fbuf)

  {

  	struct videobuf_vmalloc_memory *mem = vb->priv;

  	int pages;

  
  	BUG_ON(!mem);

  	MAGIC_CHECK(mem->magic, MAGIC_VMAL_MEM);

  	switch (vb->memory) {
  	case V4L2_MEMORY_MMAP:
  		dprintk(1, "%s memory method MMAP
  ", __func__);

  		/* All handling should be done by __videobuf_mmap_mapper() */

  		if (!mem->vaddr) {

  			printk(KERN_ERR "memory is not alloced/mmapped.
  ");
  			return -EINVAL;
  		}
  		break;
  	case V4L2_MEMORY_USERPTR:

  		pages = PAGE_ALIGN(vb->size);

  		dprintk(1, "%s memory method USERPTR
  ", __func__);

  		if (vb->baddr) {
  			printk(KERN_ERR "USERPTR is currently not supported
  ");
  			return -EINVAL;
  		}

  		/* The only USERPTR currently supported is the one needed for

  		 * read() method.

  		 */

  		mem->vaddr = vmalloc_user(pages);
  		if (!mem->vaddr) {

  			printk(KERN_ERR "vmalloc (%d pages) failed
  ", pages);
  			return -ENOMEM;

  		}

  		dprintk(1, "vmalloc is at addr %p (%d pages)
  ",

  			mem->vaddr, pages);

  
  #if 0
  		int rc;
  		/* Kernel userptr is used also by read() method. In this case,
  		   there's no need to remap, since data will be copied to user
  		 */
  		if (!vb->baddr)
  			return 0;
  
  		/* FIXME: to properly support USERPTR, remap should occur.

  		   The code below won't work, since mem->vma = NULL

  		 */
  		/* Try to remap memory */
  		rc = remap_vmalloc_range(mem->vma, (void *)vb->baddr, 0);
  		if (rc < 0) {

  			printk(KERN_ERR "mmap: remap failed with error %d", rc);

  			return -ENOMEM;
  		}
  #endif
  
  		break;

  	case V4L2_MEMORY_OVERLAY:
  	default:
  		dprintk(1, "%s memory method OVERLAY/unknown
  ", __func__);
  
  		/* Currently, doesn't support V4L2_MEMORY_OVERLAY */
  		printk(KERN_ERR "Memory method currently unsupported.
  ");
  		return -EINVAL;

  	}
  
  	return 0;
  }

  static int __videobuf_mmap_mapper(struct videobuf_queue *q,

  				  struct videobuf_buffer *buf,
  				  struct vm_area_struct *vma)

  {

  	struct videobuf_vmalloc_memory *mem;

  	struct videobuf_mapping *map;

  	int retval, pages;

  	dprintk(1, "%s
  ", __func__);

  
  	/* create mapping + update buffer list */

  	map = kzalloc(sizeof(struct videobuf_mapping), GFP_KERNEL);

  	if (NULL == map)
  		return -ENOMEM;

  	buf->map = map;

  	map->q     = q;

  	buf->baddr = vma->vm_start;

  	mem = buf->priv;

  	BUG_ON(!mem);
  	MAGIC_CHECK(mem->magic, MAGIC_VMAL_MEM);

  	pages = PAGE_ALIGN(vma->vm_end - vma->vm_start);

  	mem->vaddr = vmalloc_user(pages);
  	if (!mem->vaddr) {

  		printk(KERN_ERR "vmalloc (%d pages) failed
  ", pages);
  		goto error;
  	}

  	dprintk(1, "vmalloc is at addr %p (%d pages)
  ", mem->vaddr, pages);

  	/* Try to remap memory */

  	retval = remap_vmalloc_range(vma, mem->vaddr, 0);

  	if (retval < 0) {
  		printk(KERN_ERR "mmap: remap failed with error %d. ", retval);

  		vfree(mem->vaddr);

  		goto error;

  	}

  	vma->vm_ops          = &videobuf_vm_ops;
  	vma->vm_flags       |= VM_DONTEXPAND | VM_RESERVED;
  	vma->vm_private_data = map;

  	dprintk(1, "mmap %p: q=%p %08lx-%08lx (%lx) pgoff %08lx buf %d
  ",

  		map, q, vma->vm_start, vma->vm_end,

  		(long int)buf->bsize,
  		vma->vm_pgoff, buf->i);

  
  	videobuf_vm_open(vma);

  	return 0;
  
  error:
  	mem = NULL;
  	kfree(map);
  	return -ENOMEM;

  }

  static struct videobuf_qtype_ops qops = {
  	.magic        = MAGIC_QTYPE_OPS,

  	.alloc_vb     = __videobuf_alloc_vb,

  	.iolock       = __videobuf_iolock,

  	.mmap_mapper  = __videobuf_mmap_mapper,

  	.vaddr        = videobuf_to_vmalloc,

  };

  void videobuf_queue_vmalloc_init(struct videobuf_queue *q,

  			 const struct videobuf_queue_ops *ops,

  			 struct device *dev,

  			 spinlock_t *irqlock,
  			 enum v4l2_buf_type type,
  			 enum v4l2_field field,
  			 unsigned int msize,

  			 void *priv,
  			 struct mutex *ext_lock)

  {

  	videobuf_queue_core_init(q, ops, dev, irqlock, type, field, msize,

  				 priv, &qops, ext_lock);

  }

  EXPORT_SYMBOL_GPL(videobuf_queue_vmalloc_init);

  void *videobuf_to_vmalloc(struct videobuf_buffer *buf)

  {

  	struct videobuf_vmalloc_memory *mem = buf->priv;
  	BUG_ON(!mem);
  	MAGIC_CHECK(mem->magic, MAGIC_VMAL_MEM);

  	return mem->vaddr;

  }
  EXPORT_SYMBOL_GPL(videobuf_to_vmalloc);

  void videobuf_vmalloc_free(struct videobuf_buffer *buf)

  {

  	struct videobuf_vmalloc_memory *mem = buf->priv;

  	/* mmapped memory can't be freed here, otherwise mmapped region
  	   would be released, while still needed. In this case, the memory
  	   release should happen inside videobuf_vm_close().
  	   So, it should free memory only if the memory were allocated for
  	   read() operation.
  	 */

  	if ((buf->memory != V4L2_MEMORY_USERPTR) || buf->baddr)

  		return;

  	if (!mem)
  		return;
  
  	MAGIC_CHECK(mem->magic, MAGIC_VMAL_MEM);

  	vfree(mem->vaddr);
  	mem->vaddr = NULL;

  	return;
  }
  EXPORT_SYMBOL_GPL(videobuf_vmalloc_free);