path: root/arch/arm/plat-omap/iovmm.c

/*
 * omap iommu: simple virtual address space management
 *
 * Copyright (C) 2008-2009 Nokia Corporation
 *
 * Written by Hiroshi DOYU <Hiroshi.DOYU@nokia.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/err.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/device.h>
#include <linux/scatterlist.h>

#include <asm/cacheflush.h>
#include <asm/mach/map.h>

#include <plat/iommu.h>
#include <plat/iovmm.h>

#include "iopgtable.h"

/*
 * A device driver needs to create address mappings between:
 *
 * - iommu/device address
 * - physical address
 * - mpu virtual address
 *
 * There are 4 possible patterns for them:
 *
 *    |iova/			  mapping		iommu_		page
 *    | da	pa	va	(d)-(p)-(v)		function	type
 *  ---------------------------------------------------------------------------
 *  1 | c	c	c	 1 - 1 - 1	  _kmap() / _kunmap()	s
 *  2 | c	c,a	c	 1 - 1 - 1	_kmalloc()/ _kfree()	s
 *  3 | c	d	c	 1 - n - 1	  _vmap() / _vunmap()	s
 *  4 | c	d,a	c	 1 - n - 1	_vmalloc()/ _vfree()	n*
 *
 *
 *	'iova':	device iommu virtual address
 *	'da':	alias of 'iova'
 *	'pa':	physical address
 *	'va':	mpu virtual address
 *
 *	'c':	contiguous memory area
 *	'd':	discontiguous memory area
 *	'a':	anonymous memory allocation
 *	'()':	optional feature
 *
 *	'n':	a normal page(4KB) size is used.
 *	's':	multiple iommu superpage(16MB, 1MB, 64KB, 4KB) size is used.
 *
 *	'*':	not yet, but feasible.
 */

static struct kmem_cache *iovm_area_cachep;

/* return total bytes of sg buffers */
static size_t sgtable_len(const struct sg_table *sgt)
{
	unsigned int i, total = 0;
	struct scatterlist *sg;

	if (!sgt)
		return 0;

	for_each_sg(sgt->sgl, sg, sgt->nents, i) {
		size_t bytes;

		bytes = sg_dma_len(sg);

		if (!iopgsz_ok(bytes)) {
			pr_err("%s: sg[%d] not iommu pagesize(%x)\n",
			       __func__, i, bytes);
			return 0;
		}

		total += bytes;
	}

	return total;
}
#define sgtable_ok(x)	(!!sgtable_len(x))

static unsigned max_alignment(u32 addr)
{
	int i;
	unsigned pagesize[] = { SZ_16M, SZ_1M, SZ_64K, SZ_4K, };
	for (i = 0; i < ARRAY_SIZE(pagesize) && addr & (pagesize[i] - 1); i++)
		;
	return (i < ARRAY_SIZE(pagesize)) ? pagesize[i] : 0;
}

/*
 * calculate the optimal number sg elements from total bytes based on
 * iommu superpages
 */
static unsigned sgtable_nents(size_t bytes, u32 da, u32 pa)
{
	unsigned nr_entries = 0, ent_sz;

	if (!IS_ALIGNED(bytes, PAGE_SIZE)) {
		pr_err("%s: wrong size %08x\n", __func__, bytes);
		return 0;
	}

	while (bytes) {
		ent_sz = max_alignment(da | pa);
		ent_sz = min_t(unsigned, ent_sz, iopgsz_max(bytes));
		nr_entries++;
		da += ent_sz;
		pa += ent_sz;
		bytes -= ent_sz;
	}

	return nr_entries;
}

/* allocate and initialize sg_table header(a kind of 'superblock') */
static struct sg_table *sgtable_alloc(const size_t bytes, u32 flags,
							u32 da, u32 pa)
{
	unsigned int nr_entries;
	int err;
	struct sg_table *sgt;

	if (!bytes)
		return ERR_PTR(-EINVAL);

	if (!IS_ALIGNED(bytes, PAGE_SIZE))
		return ERR_PTR(-EINVAL);

	if (flags & IOVMF_LINEAR) {
		nr_entries = sgtable_nents(bytes, da, pa);
		if (!nr_entries)
			return ERR_PTR(-EINVAL);
	} else
		nr_entries =  bytes / PAGE_SIZE;

	sgt = kzalloc(sizeof(*sgt), GFP_KERNEL);
	if (!sgt)
		return ERR_PTR(-ENOMEM);

	err = sg_alloc_table(sgt, nr_entries, GFP_KERNEL);
	if (err) {
		kfree(sgt);
		return ERR_PTR(err);
	}

	pr_debug("%s: sgt:%p(%d entries)\n", __func__, sgt, nr_entries);

	return sgt;
}

/* free sg_table header(a kind of superblock) */
static void sgtable_free(struct sg_table *sgt)
{
	if (!sgt)
		return;

	sg_free_table(sgt);
	kfree(sgt);

	pr_debug("%s: sgt:%p\n", __func__, sgt);
}

/* map 'sglist' to a contiguous mpu virtual area and return 'va' */
static void *vmap_sg(const struct sg_table *sgt)
{
	u32 va;
	size_t total;
	unsigned int i;
	struct scatterlist *sg;
	struct vm_struct *new;
	const struct mem_type *mtype;

	mtype = get_mem_type(MT_DEVICE);
	if (!mtype)
		return ERR_PTR(-EINVAL);

	total = sgtable_len(sgt);
	if (!total)
		return ERR_PTR(-EINVAL);

	new = __get_vm_area(total, VM_IOREMAP, VMALLOC_START, VMALLOC_END);
	if (!new)
		return ERR_PTR(-ENOMEM);
	va = (u32)new->addr;

	for_each_sg(sgt->sgl, sg, sgt->nents, i) {
		size_t