/*
 * 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/module.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/device.h>
#include <linux/scatterlist.h>
#include <linux/iommu.h>
#include <linux/omap-iommu.h>
#include <linux/platform_data/iommu-omap.h>

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

#include "omap-iopgtable.h"
#include "omap-iommu.h"

/*
 * IOVMF_FLAGS: attribute for iommu virtual memory area(iovma)
 *
 * lower 16 bit is used for h/w and upper 16 bit is for s/w.
 */
#define IOVMF_SW_SHIFT          16

/*
 * iovma: h/w flags derived from cam and ram attribute
 */
#define IOVMF_CAM_MASK          (~((1 << 10) - 1))
#define IOVMF_RAM_MASK          (~IOVMF_CAM_MASK)

#define IOVMF_PGSZ_MASK         (3 << 0)
#define IOVMF_PGSZ_1M           MMU_CAM_PGSZ_1M
#define IOVMF_PGSZ_64K          MMU_CAM_PGSZ_64K
#define IOVMF_PGSZ_4K           MMU_CAM_PGSZ_4K
#define IOVMF_PGSZ_16M          MMU_CAM_PGSZ_16M

#define IOVMF_ENDIAN_MASK       (1 << 9)
#define IOVMF_ENDIAN_BIG        MMU_RAM_ENDIAN_BIG

#define IOVMF_ELSZ_MASK         (3 << 7)
#define IOVMF_ELSZ_16           MMU_RAM_ELSZ_16
#define IOVMF_ELSZ_32           MMU_RAM_ELSZ_32
#define IOVMF_ELSZ_NONE         MMU_RAM_ELSZ_NONE

#define IOVMF_MIXED_MASK        (1 << 6)
#define IOVMF_MIXED             MMU_RAM_MIXED

/*
 * iovma: s/w flags, used for mapping and umapping internally.
 */
#define IOVMF_MMIO              (1 << IOVMF_SW_SHIFT)
#define IOVMF_ALLOC             (2 << IOVMF_SW_SHIFT)
#define IOVMF_ALLOC_MASK        (3 << IOVMF_SW_SHIFT)

/* "superpages" is supported just with physically linear pages */
#define IOVMF_DISCONT           (1 << (2 + IOVMF_SW_SHIFT))
#define IOVMF_LINEAR            (2 << (2 + IOVMF_SW_SHIFT))
#define IOVMF_LINEAR_MASK       (3 << (2 + IOVMF_SW_SHIFT))

#define IOVMF_DA_FIXED          (1 << (4 + IOVMF_SW_SHIFT))

static struct kmem_cache *iovm_area_cachep;

/* return the offset of the first scatterlist entry in a sg table */
static unsigned int sgtable_offset(const struct sg_table *sgt)
{
        if (!sgt || !sgt->nents)
                return 0;

        return sgt->sgl->offset;
}

/* 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->length + sg->offset;

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

                if (i && sg->offset) {
                        pr_err("%s: sg[%d] offset not allowed in internal entries\n",
                                __func__, i);
                        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 bytes;
                u32 pa;
                int err;

                pa = sg_phys(sg) - sg->offset;
                bytes = sg->length + sg->offset;

                BUG_ON(bytes != PAGE_SIZE);

                err = ioremap_page(va,  pa, mtype);
                if (err)
                        goto err_out;

                va += bytes;
        }

        flush_cache_vmap((unsigned long)new->addr,
                                (unsigned long)(new->addr + total));
        return new->addr;

err_out:
        WARN_ON(1); /* FIXME: cleanup some mpu mappings */
        vunmap(new->addr);
        return ERR_PTR(-EAGAIN);
}

static inline void vunmap_sg(const void *va)
{
        vunmap(va);
}

static struct iovm_struct *__find_iovm_area(struct omap_iommu *obj,
                                                        const u32 da)
{
        struct iovm_struct *tmp;

        list_for_each_entry(tmp, &obj->mmap, list) {
                if ((da >= tmp->da_start) && (da < tmp->da_end)) {
                        size_t len;

                        len = tmp->da_end - tmp->da_start;

                        dev_dbg(obj->dev, "%s: %08x-%08x-%08x(%x) %08x\n",
                                __func__, tmp->da_start, da, tmp->da_end, len,
                                tmp->flags);

                        return tmp;
                }
        }

        return NULL;
}

/**
 * omap_find_iovm_area  -  find iovma which includes @da
 * @dev:        client device
 * @da:         iommu device virtual address
 *
 * Find the existing iovma starting at @da
 */
struct iovm_struct *omap_find_iovm_area(struct device *dev, u32 da)
{
        struct omap_iommu *obj = dev_to_omap_iommu(dev);
        struct iovm_struct *area;

        mutex_lock(&obj->mmap_lock);
        area = __find_iovm_area(obj, da);
        mutex_unlock(&obj->mmap_lock);

        return area;
}
EXPORT_SYMBOL_GPL(omap_find_iovm_area);

/*
 * This finds the hole(area) which fits the requested address and len
 * in iovmas mmap, and returns the new allocated iovma.
 */
static struct iovm_struct *alloc_iovm_area(struct omap_iommu *obj, u32 da,
                                           size_t bytes, u32 flags)
{
        struct iovm_struct *new, *tmp;
        u32 start, prev_end, alignment;

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

        start = da;
        alignment = PAGE_SIZE;

        if (~flags & IOVMF_DA_FIXED) {
                /* Don't map address 0 */
                start = obj->da_start ? obj->da_start : alignment;

                if (flags & IOVMF_LINEAR)
                        alignment = iopgsz_max(bytes);
                start = roundup(start, alignment);
        } else if (start < obj->da_start || start > obj->da_end ||
                                        obj->da_end - start < bytes) {
                return ERR_PTR(-EINVAL);
        }

        tmp = NULL;
        if (list_empty(&obj->mmap))
                goto found;

        prev_end = 0;
        list_for_each_entry(tmp, &obj->mmap, list) {

                if (prev_end > start)
                        break;

                if (tmp->da_start > start && (tmp->da_start - start) >= bytes)
                        goto found;

                if (tmp->da_end >= start && ~flags & IOVMF_DA_FIXED)
                        start = roundup(tmp->da_end + 1, alignment);

                prev_end = tmp->da_end;
        }

        if ((start >= prev_end) && (obj->da_end - start >= bytes))
                goto found;

        dev_dbg(obj->dev, "%s: no space to fit %08x(%x) flags: %08x\n",
                __func__, da, bytes, flags);

        return ERR_PTR(-EINVAL);

found:
        new = kmem_cache_zalloc(iovm_area_cachep, GFP_KERNEL);
        if (!new)
                return ERR_PTR(-ENOMEM);

        new->iommu = obj;
        new->da_start = start;
        new->da_end = start + bytes;
        new->flags = flags;

        /*
         * keep ascending order of iovmas
         */
        if (tmp)
                list_add_tail(&new->list, &tmp->list);
        else
                list_add(&new->list, &obj->mmap);

        dev_dbg(obj->dev, "%s: found %08x-%08x-%08x(%x) %08x\n",
                __func__, new->da_start, start, new->da_end, bytes, flags);

        return new;
}

static void free_iovm_area(struct omap_iommu *obj, struct iovm_struct *area)
{
        size_t bytes;

        BUG_ON(!obj || !area);

        bytes = area->da_end - area->da_start;

        dev_dbg(obj->dev, "%s: %08x-%08x(%x) %08x\n",
                __func__, area->da_start, area->da_end, bytes, area->flags);

        list_del(&area->list);
        kmem_cache_free(iovm_area_cachep, area);
}

/**
 * omap_da_to_va - convert (d) to (v)
 * @dev:        client device
 * @da:         iommu device virtual address
 * @va:         mpu virtual address
 *
 * Returns mpu virtual addr which corresponds to a given device virtual addr
 */
void *omap_da_to_va(struct device *dev, u32 da)
{
        struct omap_iommu *obj = dev_to_omap_iommu(dev);
        void *va = NULL;
        struct iovm_struct *area;

        mutex_lock(&obj->mmap_lock);

        area = __find_iovm_area(obj, da);
        if (!area) {
                dev_dbg(obj->dev, "%s: no da area(%08x)\n", __func__, da);
                goto out;
        }
        va = area->va;
out:
        mutex_unlock(&obj->mmap_lock);

        return va;
}
EXPORT_SYMBOL_GPL(omap_da_to_va);

static void sgtable_fill_vmalloc(struct sg_table *sgt, void *_va)
{
        unsigned int i;
        struct scatterlist *sg;
        void *va = _va;
        void *va_end;

        for_each_sg(sgt->sgl, sg, sgt->nents, i) {
                struct page *pg;
                const size_t bytes = PAGE_SIZE;

                /*
                 * iommu 'superpage' isn't supported with 'omap_iommu_vmalloc()'
                 */
                pg = vmalloc_to_page(va);
                BUG_ON(!pg);
                sg_set_page(sg, pg, bytes, 0);

                va += bytes;
        }

        va_end = _va + PAGE_SIZE * i;
}

static inline void sgtable_drain_vmalloc(struct sg_table *sgt)
{
        /*
         * Actually this is not necessary at all, just exists for
         * consistency of the code readability.
         */
        BUG_ON(!sgt);
}

/* create 'da' <-> 'pa' mapping from 'sgt' */
static int map_iovm_area(struct iommu_domain *domain, struct iovm_struct *new,
                        const struct sg_table *sgt, u32 flags)
{
        int err;
        unsigned int i, j;
        struct scatterlist *sg;
        u32 da = new->da_start;

        if (!domain || !sgt)
                return -EINVAL;

        BUG_ON(!sgtable_ok(sgt));

        for_each_sg(sgt->sgl, sg, sgt->nents, i) {
                u32 pa;
                size_t bytes;

                pa = sg_phys(sg) - sg->offset;
                bytes = sg->length + sg->offset;

                flags &= ~IOVMF_PGSZ_MASK;

                if (bytes_to_iopgsz(bytes) < 0)
                        goto err_out;

                pr_debug("%s: [%d] %08x %08x(%x)\n", __func__,
                         i, da, pa, bytes);

                err = iommu_map(domain, da, pa, bytes, flags);
                if (err)
                        goto err_out;

                da += bytes;
        }
        return 0;

err_out:
        da = new->da_start;

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

                bytes = sg->length + sg->offset;

                /* ignore failures.. we're already handling one */
                iommu_unmap(domain, da, bytes);

                da += bytes;
        }
        return err;
}

/* release 'da' <-> 'pa' mapping */
static void unmap_iovm_area(struct iommu_domain *domain, struct omap_iommu *obj,
                                                struct iovm_struct *area)
{
        u32 start;
        size_t total = area->da_end - area->da_start;
        const struct sg_table *sgt = area->sgt;
        struct scatterlist *sg;
        int i;
        size_t unmapped;

        BUG_ON(!sgtable_ok(sgt));
        BUG_ON((!total) || !IS_ALIGNED(total, PAGE_SIZE));

        start = area->da_start;
        for_each_sg(sgt->sgl, sg, sgt->nents, i) {
                size_t bytes;

                bytes = sg->length + sg->offset;

                unmapped = iommu_unmap(domain, start, bytes);
                if (unmapped < bytes)
                        break;

                dev_dbg(obj->dev, "%s: unmap %08x(%x) %08x\n",
                                __func__, start, bytes, area->flags);

                BUG_ON(!IS_ALIGNED(bytes, PAGE_SIZE));

                total -= bytes;
                start += bytes;
        }
        BUG_ON(total);
}

/* template function for all unmapping */
static struct sg_table *unmap_vm_area(struct iommu_domain *domain,
                                      struct omap_iommu *obj, const u32 da,
                                      void (*fn)(const void *), u32 flags)
{
        struct sg_table *sgt = NULL;
        struct iovm_struct *area;

        if (!IS_ALIGNED(da, PAGE_SIZE)) {
                dev_err(obj->dev, "%s: alignment err(%08x)\n", __func__, da);
                return NULL;
        }

        mutex_lock(&obj->mmap_lock);

        area = __find_iovm_area(obj, da);
        if (!area) {
                dev_dbg(obj->dev, "%s: no da area(%08x)\n", __func__, da);
                goto out;
        }

        if ((area->flags & flags) != flags) {
                dev_err(obj->dev, "%s: wrong flags(%08x)\n", __func__,
                        area->flags);
                goto out;
        }
        sgt = (struct sg_table *)area->sgt;

        unmap_iovm_area(domain, obj, area);

        fn(area->va);

        dev_dbg(obj->dev, "%s: %08x-%08x-%08x(%x) %08x\n", __func__,
                area->da_start, da, area->da_end,
                area->da_end - area->da_start, area->flags);

        free_iovm_area(obj, area);
out:
        mutex_unlock(&obj->mmap_lock);

        return sgt;
}

static u32 map_iommu_region(struct iommu_domain *domain, struct omap_iommu *obj,
                                u32 da, const struct sg_table *sgt, void *va,
                                size_t bytes, u32 flags)
{
        int err = -ENOMEM;
        struct iovm_struct *new;

        mutex_lock(&obj->mmap_lock);

        new = alloc_iovm_area(obj, da, bytes, flags);
        if (IS_ERR(new)) {
                err = PTR_ERR(new);
                goto err_alloc_iovma;
        }
        new->va = va;
        new->sgt = sgt;

        if (map_iovm_area(domain, new, sgt, new->flags))
                goto err_map;

        mutex_unlock(&obj->mmap_lock);

        dev_dbg(obj->dev, "%s: da:%08x(%x) flags:%08x va:%p\n",
                __func__, new->da_start, bytes, new->flags, va);

        return new->da_start;

err_map:
        free_iovm_area(obj, new);
err_alloc_iovma:
        mutex_unlock(&obj->mmap_lock);
        return err;
}

static inline u32
__iommu_vmap(struct iommu_domain *domain, struct omap_iommu *obj,
                                u32 da, const struct sg_table *sgt,
                                void *va, size_t bytes, u32 flags)
{
        return map_iommu_region(domain, obj, da, sgt, va, bytes, flags);
}

/**
 * omap_iommu_vmap  -  (d)-(p)-(v) address mapper
 * @domain:     iommu domain
 * @dev:        client device
 * @sgt:        address of scatter gather table
 * @flags:      iovma and page property
 *
 * Creates 1-n-1 mapping with given @sgt and returns @da.
 * All @sgt element must be io page size aligned.
 */
u32 omap_iommu_vmap(struct iommu_domain *domain, struct device *dev, u32 da,
                const struct sg_table *sgt, u32 flags)
{
        struct omap_iommu *obj = dev_to_omap_iommu(dev);
        size_t bytes;
        void *va = NULL;

        if (!obj || !obj->dev || !sgt)
                return -EINVAL;

        bytes = sgtable_len(sgt);
        if (!bytes)
                return -EINVAL;
        bytes = PAGE_ALIGN(bytes);

        if (flags & IOVMF_MMIO) {
                va = vmap_sg(sgt);
                if (IS_ERR(va))
                        return PTR_ERR(va);
        }

        flags |= IOVMF_DISCONT;
        flags |= IOVMF_MMIO;

        da = __iommu_vmap(domain, obj, da, sgt, va, bytes, flags);
        if (IS_ERR_VALUE(da))
                vunmap_sg(va);

        return da + sgtable_offset(sgt);
}
EXPORT_SYMBOL_GPL(omap_iommu_vmap);

/**
 * omap_iommu_vunmap  -  release virtual mapping obtained by 'omap_iommu_vmap()'
 * @domain:     iommu domain
 * @dev:        client device
 * @da:         iommu device virtual address
 *
 * Free the iommu virtually contiguous memory area starting at
 * @da, which was returned by 'omap_iommu_vmap()'.
 */
struct sg_table *
omap_iommu_vunmap(struct iommu_domain *domain, struct device *dev, u32 da)
{
        struct omap_iommu *obj = dev_to_omap_iommu(dev);
        struct sg_table *sgt;
        /*
         * 'sgt' is allocated before 'omap_iommu_vmalloc()' is called.
         * Just returns 'sgt' to the caller to free
         */
        da &= PAGE_MASK;
        sgt = unmap_vm_area(domain, obj, da, vunmap_sg,
                                        IOVMF_DISCONT | IOVMF_MMIO);
        if (!sgt)
                dev_dbg(obj->dev, "%s: No sgt\n", __func__);
        return sgt;
}
EXPORT_SYMBOL_GPL(omap_iommu_vunmap);

/**
 * omap_iommu_vmalloc  -  (d)-(p)-(v) address allocator and mapper
 * @dev:        client device
 * @da:         contiguous iommu virtual memory
 * @bytes:      allocation size
 * @flags:      iovma and page property
 *
 * Allocate @bytes linearly and creates 1-n-1 mapping and returns
 * @da again, which might be adjusted if 'IOVMF_DA_FIXED' is not set.
 */
u32
omap_iommu_vmalloc(struct iommu_domain *domain, struct device *dev, u32 da,
                                                size_t bytes, u32 flags)
{
        struct omap_iommu *obj = dev_to_omap_iommu(dev);
        void *va;
        struct sg_table *sgt;

        if (!obj || !obj->dev || !bytes)
                return -EINVAL;

        bytes = PAGE_ALIGN(bytes);

        va = vmalloc(bytes);
        if (!va)
                return -ENOMEM;

        flags |= IOVMF_DISCONT;
        flags |= IOVMF_ALLOC;

        sgt = sgtable_alloc(bytes, flags, da, 0);
        if (IS_ERR(sgt)) {
                da = PTR_ERR(sgt);
                goto err_sgt_alloc;
        }
        sgtable_fill_vmalloc(sgt, va);

        da = __iommu_vmap(domain, obj, da, sgt, va, bytes, flags);
        if (IS_ERR_VALUE(da))
                goto err_iommu_vmap;

        return da;

err_iommu_vmap:
        sgtable_drain_vmalloc(sgt);
        sgtable_free(sgt);
err_sgt_alloc:
        vfree(va);
        return da;
}
EXPORT_SYMBOL_GPL(omap_iommu_vmalloc);

/**
 * omap_iommu_vfree  -  release memory allocated by 'omap_iommu_vmalloc()'
 * @dev:        client device
 * @da:         iommu device virtual address
 *
 * Frees the iommu virtually continuous memory area starting at
 * @da, as obtained from 'omap_iommu_vmalloc()'.
 */
void omap_iommu_vfree(struct iommu_domain *domain, struct device *dev,
                                                                const u32 da)
{
        struct omap_iommu *obj = dev_to_omap_iommu(dev);
        struct sg_table *sgt;

        sgt = unmap_vm_area(domain, obj, da, vfree,
                                                IOVMF_DISCONT | IOVMF_ALLOC);
        if (!sgt)
                dev_dbg(obj->dev, "%s: No sgt\n", __func__);
        sgtable_free(sgt);
}
EXPORT_SYMBOL_GPL(omap_iommu_vfree);

static int __init iovmm_init(void)
{
        const unsigned long flags = SLAB_HWCACHE_ALIGN;
        struct kmem_cache *p;

        p = kmem_cache_create("iovm_area_cache", sizeof(struct iovm_struct), 0,
                              flags, NULL);
        if (!p)
                return -ENOMEM;
        iovm_area_cachep = p;

        return 0;
}
module_init(iovmm_init);

static void __exit iovmm_exit(void)
{
        kmem_cache_destroy(iovm_area_cachep);
}
module_exit(iovmm_exit);

MODULE_DESCRIPTION("omap iommu: simple virtual address space management");
MODULE_AUTHOR("Hiroshi DOYU <Hiroshi.DOYU@nokia.com>");
MODULE_LICENSE("GPL v2");