nvme: depend on INFINIBAND_ADDR_TRANS

[mirror_ubuntu-bionic-kernel.git] / drivers / iommu / omap-iommu.c

/*
 * omap iommu: tlb and pagetable primitives
 *
 * Copyright (C) 2008-2010 Nokia Corporation
 * Copyright (C) 2013-2017 Texas Instruments Incorporated - http://www.ti.com/
 *
 * Written by Hiroshi DOYU <Hiroshi.DOYU@nokia.com>,
 *              Paul Mundt and Toshihiro Kobayashi
 *
 * 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/dma-mapping.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/interrupt.h>
#include <linux/ioport.h>
#include <linux/platform_device.h>
#include <linux/iommu.h>
#include <linux/omap-iommu.h>
#include <linux/mutex.h>
#include <linux/spinlock.h>
#include <linux/io.h>
#include <linux/pm_runtime.h>
#include <linux/of.h>
#include <linux/of_iommu.h>
#include <linux/of_irq.h>
#include <linux/of_platform.h>
#include <linux/regmap.h>
#include <linux/mfd/syscon.h>

#include <linux/platform_data/iommu-omap.h>

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

static const struct iommu_ops omap_iommu_ops;

#define to_iommu(dev)                                                   \
        ((struct omap_iommu *)platform_get_drvdata(to_platform_device(dev)))

/* bitmap of the page sizes currently supported */
#define OMAP_IOMMU_PGSIZES      (SZ_4K | SZ_64K | SZ_1M | SZ_16M)

#define MMU_LOCK_BASE_SHIFT     10
#define MMU_LOCK_BASE_MASK      (0x1f << MMU_LOCK_BASE_SHIFT)
#define MMU_LOCK_BASE(x)        \
        ((x & MMU_LOCK_BASE_MASK) >> MMU_LOCK_BASE_SHIFT)

#define MMU_LOCK_VICT_SHIFT     4
#define MMU_LOCK_VICT_MASK      (0x1f << MMU_LOCK_VICT_SHIFT)
#define MMU_LOCK_VICT(x)        \
        ((x & MMU_LOCK_VICT_MASK) >> MMU_LOCK_VICT_SHIFT)

static struct platform_driver omap_iommu_driver;
static struct kmem_cache *iopte_cachep;

/**
 * to_omap_domain - Get struct omap_iommu_domain from generic iommu_domain
 * @dom:        generic iommu domain handle
 **/
static struct omap_iommu_domain *to_omap_domain(struct iommu_domain *dom)
{
        return container_of(dom, struct omap_iommu_domain, domain);
}

/**
 * omap_iommu_save_ctx - Save registers for pm off-mode support
 * @dev:        client device
 **/
void omap_iommu_save_ctx(struct device *dev)
{
        struct omap_iommu_arch_data *arch_data = dev->archdata.iommu;
        struct omap_iommu *obj;
        u32 *p;
        int i;

        if (!arch_data)
                return;

        while (arch_data->iommu_dev) {
                obj = arch_data->iommu_dev;
                p = obj->ctx;
                for (i = 0; i < (MMU_REG_SIZE / sizeof(u32)); i++) {
                        p[i] = iommu_read_reg(obj, i * sizeof(u32));
                        dev_dbg(obj->dev, "%s\t[%02d] %08x\n", __func__, i,
                                p[i]);
                }
                arch_data++;
        }
}
EXPORT_SYMBOL_GPL(omap_iommu_save_ctx);

/**
 * omap_iommu_restore_ctx - Restore registers for pm off-mode support
 * @dev:        client device
 **/
void omap_iommu_restore_ctx(struct device *dev)
{
        struct omap_iommu_arch_data *arch_data = dev->archdata.iommu;
        struct omap_iommu *obj;
        u32 *p;
        int i;

        if (!arch_data)
                return;

        while (arch_data->iommu_dev) {
                obj = arch_data->iommu_dev;
                p = obj->ctx;
                for (i = 0; i < (MMU_REG_SIZE / sizeof(u32)); i++) {
                        iommu_write_reg(obj, p[i], i * sizeof(u32));
                        dev_dbg(obj->dev, "%s\t[%02d] %08x\n", __func__, i,
                                p[i]);
                }
                arch_data++;
        }
}
EXPORT_SYMBOL_GPL(omap_iommu_restore_ctx);

static void dra7_cfg_dspsys_mmu(struct omap_iommu *obj, bool enable)
{
        u32 val, mask;

        if (!obj->syscfg)
                return;

        mask = (1 << (obj->id * DSP_SYS_MMU_CONFIG_EN_SHIFT));
        val = enable ? mask : 0;
        regmap_update_bits(obj->syscfg, DSP_SYS_MMU_CONFIG, mask, val);
}

static void __iommu_set_twl(struct omap_iommu *obj, bool on)
{
        u32 l = iommu_read_reg(obj, MMU_CNTL);

        if (on)
                iommu_write_reg(obj, MMU_IRQ_TWL_MASK, MMU_IRQENABLE);
        else
                iommu_write_reg(obj, MMU_IRQ_TLB_MISS_MASK, MMU_IRQENABLE);

        l &= ~MMU_CNTL_MASK;
        if (on)
                l |= (MMU_CNTL_MMU_EN | MMU_CNTL_TWL_EN);
        else
                l |= (MMU_CNTL_MMU_EN);

        iommu_write_reg(obj, l, MMU_CNTL);
}

static int omap2_iommu_enable(struct omap_iommu *obj)
{
        u32 l, pa;

        if (!obj->iopgd || !IS_ALIGNED((u32)obj->iopgd,  SZ_16K))
                return -EINVAL;

        pa = virt_to_phys(obj->iopgd);
        if (!IS_ALIGNED(pa, SZ_16K))
                return -EINVAL;

        l = iommu_read_reg(obj, MMU_REVISION);
        dev_info(obj->dev, "%s: version %d.%d\n", obj->name,
                 (l >> 4) & 0xf, l & 0xf);

        iommu_write_reg(obj, pa, MMU_TTB);

        dra7_cfg_dspsys_mmu(obj, true);

        if (obj->has_bus_err_back)
                iommu_write_reg(obj, MMU_GP_REG_BUS_ERR_BACK_EN, MMU_GP_REG);

        __iommu_set_twl(obj, true);

        return 0;
}

static void omap2_iommu_disable(struct omap_iommu *obj)
{
        u32 l = iommu_read_reg(obj, MMU_CNTL);

        l &= ~MMU_CNTL_MASK;
        iommu_write_reg(obj, l, MMU_CNTL);
        dra7_cfg_dspsys_mmu(obj, false);

        dev_dbg(obj->dev, "%s is shutting down\n", obj->name);
}

static int iommu_enable(struct omap_iommu *obj)
{
        int err;
        struct platform_device *pdev = to_platform_device(obj->dev);
        struct iommu_platform_data *pdata = dev_get_platdata(&pdev->dev);

        if (pdata && pdata->deassert_reset) {
                err = pdata->deassert_reset(pdev, pdata->reset_name);
                if (err) {
                        dev_err(obj->dev, "deassert_reset failed: %d\n", err);
                        return err;
                }
        }

        pm_runtime_get_sync(obj->dev);

        err = omap2_iommu_enable(obj);

        return err;
}

static void iommu_disable(struct omap_iommu *obj)
{
        struct platform_device *pdev = to_platform_device(obj->dev);
        struct iommu_platform_data *pdata = dev_get_platdata(&pdev->dev);

        omap2_iommu_disable(obj);

        pm_runtime_put_sync(obj->dev);

        if (pdata && pdata->assert_reset)
                pdata->assert_reset(pdev, pdata->reset_name);
}

/*
 *      TLB operations
 */
static u32 iotlb_cr_to_virt(struct cr_regs *cr)
{
        u32 page_size = cr->cam & MMU_CAM_PGSZ_MASK;
        u32 mask = get_cam_va_mask(cr->cam & page_size);

        return cr->cam & mask;
}

static u32 get_iopte_attr(struct iotlb_entry *e)
{
        u32 attr;

        attr = e->mixed << 5;
        attr |= e->endian;
        attr |= e->elsz >> 3;
        attr <<= (((e->pgsz == MMU_CAM_PGSZ_4K) ||
                        (e->pgsz == MMU_CAM_PGSZ_64K)) ? 0 : 6);
        return attr;
}

static u32 iommu_report_fault(struct omap_iommu *obj, u32 *da)
{
        u32 status, fault_addr;

        status = iommu_read_reg(obj, MMU_IRQSTATUS);
        status &= MMU_IRQ_MASK;
        if (!status) {
                *da = 0;
                return 0;
        }

        fault_addr = iommu_read_reg(obj, MMU_FAULT_AD);
        *da = fault_addr;

        iommu_write_reg(obj, status, MMU_IRQSTATUS);

        return status;
}

void iotlb_lock_get(struct omap_iommu *obj, struct iotlb_lock *l)
{
        u32 val;

        val = iommu_read_reg(obj, MMU_LOCK);

        l->base = MMU_LOCK_BASE(val);
        l->vict = MMU_LOCK_VICT(val);
}

void iotlb_lock_set(struct omap_iommu *obj, struct iotlb_lock *l)
{
        u32 val;

        val = (l->base << MMU_LOCK_BASE_SHIFT);
        val |= (l->vict << MMU_LOCK_VICT_SHIFT);

        iommu_write_reg(obj, val, MMU_LOCK);
}

static void iotlb_read_cr(struct omap_iommu *obj, struct cr_regs *cr)
{
        cr->cam = iommu_read_reg(obj, MMU_READ_CAM);
        cr->ram = iommu_read_reg(obj, MMU_READ_RAM);
}

static void iotlb_load_cr(struct omap_iommu *obj, struct cr_regs *cr)
{
        iommu_write_reg(obj, cr->cam | MMU_CAM_V, MMU_CAM);
        iommu_write_reg(obj, cr->ram, MMU_RAM);

        iommu_write_reg(obj, 1, MMU_FLUSH_ENTRY);
        iommu_write_reg(obj, 1, MMU_LD_TLB);
}

/* only used in iotlb iteration for-loop */
struct cr_regs __iotlb_read_cr(struct omap_iommu *obj, int n)
{
        struct cr_regs cr;
        struct iotlb_lock l;

        iotlb_lock_get(obj, &l);
        l.vict = n;
        iotlb_lock_set(obj, &l);
        iotlb_read_cr(obj, &cr);

        return cr;
}

#ifdef PREFETCH_IOTLB
static struct cr_regs *iotlb_alloc_cr(struct omap_iommu *obj,
                                      struct iotlb_entry *e)
{
        struct cr_regs *cr;

        if (!e)
                return NULL;

        if (e->da & ~(get_cam_va_mask(e->pgsz))) {
                dev_err(obj->dev, "%s:\twrong alignment: %08x\n", __func__,
                        e->da);
                return ERR_PTR(-EINVAL);
        }

        cr = kmalloc(sizeof(*cr), GFP_KERNEL);
        if (!cr)
                return ERR_PTR(-ENOMEM);

        cr->cam = (e->da & MMU_CAM_VATAG_MASK) | e->prsvd | e->pgsz | e->valid;
        cr->ram = e->pa | e->endian | e->elsz | e->mixed;

        return cr;
}

/**
 * load_iotlb_entry - Set an iommu tlb entry
 * @obj:        target iommu
 * @e:          an iommu tlb entry info
 **/
static int load_iotlb_entry(struct omap_iommu *obj, struct iotlb_entry *e)
{
        int err = 0;
        struct iotlb_lock l;
        struct cr_regs *cr;

        if (!obj || !obj->nr_tlb_entries || !e)
                return -EINVAL;

        pm_runtime_get_sync(obj->dev);

        iotlb_lock_get(obj, &l);
        if (l.base == obj->nr_tlb_entries) {
                dev_warn(obj->dev, "%s: preserve entries full\n", __func__);
                err = -EBUSY;
                goto out;
        }
        if (!e->prsvd) {
                int i;
                struct cr_regs tmp;

                for_each_iotlb_cr(obj, obj->nr_tlb_entries, i, tmp)
                        if (!iotlb_cr_valid(&tmp))
                                break;

                if (i == obj->nr_tlb_entries) {
                        dev_dbg(obj->dev, "%s: full: no entry\n", __func__);
                        err = -EBUSY;
                        goto out;
                }

                iotlb_lock_get(obj, &l);
        } else {
                l.vict = l.base;
                iotlb_lock_set(obj, &l);
        }

        cr = iotlb_alloc_cr(obj, e);
        if (IS_ERR(cr)) {
                pm_runtime_put_sync(obj->dev);
                return PTR_ERR(cr);
        }

        iotlb_load_cr(obj, cr);
        kfree(cr);

        if (e->prsvd)
                l.base++;
        /* increment victim for next tlb load */
        if (++l.vict == obj->nr_tlb_entries)
                l.vict = l.base;
        iotlb_lock_set(obj, &l);
out:
        pm_runtime_put_sync(obj->dev);
        return err;
}

#else /* !PREFETCH_IOTLB */

static int load_iotlb_entry(struct omap_iommu *obj, struct iotlb_entry *e)
{
        return 0;
}

#endif /* !PREFETCH_IOTLB */

static int prefetch_iotlb_entry(struct omap_iommu *obj, struct iotlb_entry *e)
{
        return load_iotlb_entry(obj, e);
}

/**
 * flush_iotlb_page - Clear an iommu tlb entry
 * @obj:        target iommu
 * @da:         iommu device virtual address
 *
 * Clear an iommu tlb entry which includes 'da' address.
 **/
static void flush_iotlb_page(struct omap_iommu *obj, u32 da)
{
        int i;
        struct cr_regs cr;

        pm_runtime_get_sync(obj->dev);

        for_each_iotlb_cr(obj, obj->nr_tlb_entries, i, cr) {
                u32 start;
                size_t bytes;

                if (!iotlb_cr_valid(&cr))
                        continue;

                start = iotlb_cr_to_virt(&cr);
                bytes = iopgsz_to_bytes(cr.cam & 3);

                if ((start <= da) && (da < start + bytes)) {
                        dev_dbg(obj->dev, "%s: %08x<=%08x(%x)\n",
                                __func__, start, da, bytes);
                        iotlb_load_cr(obj, &cr);
                        iommu_write_reg(obj, 1, MMU_FLUSH_ENTRY);
                        break;
                }
        }
        pm_runtime_put_sync(obj->dev);

        if (i == obj->nr_tlb_entries)
                dev_dbg(obj->dev, "%s: no page for %08x\n", __func__, da);
}

/**
 * flush_iotlb_all - Clear all iommu tlb entries
 * @obj:        target iommu
 **/
static void flush_iotlb_all(struct omap_iommu *obj)
{
        struct iotlb_lock l;

        pm_runtime_get_sync(obj->dev);

        l.base = 0;
        l.vict = 0;
        iotlb_lock_set(obj, &l);

        iommu_write_reg(obj, 1, MMU_GFLUSH);

        pm_runtime_put_sync(obj->dev);
}

/*
 *      H/W pagetable operations
 */
static void flush_iopte_range(struct device *dev, dma_addr_t dma,
                              unsigned long offset, int num_entries)
{
        size_t size = num_entries * sizeof(u32);

        dma_sync_single_range_for_device(dev, dma, offset, size, DMA_TO_DEVICE);
}

static void iopte_free(struct omap_iommu *obj, u32 *iopte, bool dma_valid)
{
        dma_addr_t pt_dma;

        /* Note: freed iopte's must be clean ready for re-use */
        if (iopte) {
                if (dma_valid) {
                        pt_dma = virt_to_phys(iopte);
                        dma_unmap_single(obj->dev, pt_dma, IOPTE_TABLE_SIZE,
                                         DMA_TO_DEVICE);
                }

                kmem_cache_free(iopte_cachep, iopte);
        }
}

static u32 *iopte_alloc(struct omap_iommu *obj, u32 *iopgd,
                        dma_addr_t *pt_dma, u32 da)
{
        u32 *iopte;
        unsigned long offset = iopgd_index(da) * sizeof(da);

        /* a table has already existed */
        if (*iopgd)
                goto pte_ready;

        /*
         * do the allocation outside the page table lock
         */
        spin_unlock(&obj->page_table_lock);
        iopte = kmem_cache_zalloc(iopte_cachep, GFP_KERNEL);
        spin_lock(&obj->page_table_lock);

        if (!*iopgd) {
                if (!iopte)
                        return ERR_PTR(-ENOMEM);

                *pt_dma = dma_map_single(obj->dev, iopte, IOPTE_TABLE_SIZE,
                                         DMA_TO_DEVICE);
                if (dma_mapping_error(obj->dev, *pt_dma)) {
                        dev_err(obj->dev, "DMA map error for L2 table\n");
                        iopte_free(obj, iopte, false);
                        return ERR_PTR(-ENOMEM);
                }

                /*
                 * we rely on dma address and the physical address to be
                 * the same for mapping the L2 table
                 */
                if (WARN_ON(*pt_dma != virt_to_phys(iopte))) {
                        dev_err(obj->dev, "DMA translation error for L2 table\n");
                        dma_unmap_single(obj->dev, *pt_dma, IOPTE_TABLE_SIZE,
                                         DMA_TO_DEVICE);
                        iopte_free(obj, iopte, false);
                        return ERR_PTR(-ENOMEM);
                }

                *iopgd = virt_to_phys(iopte) | IOPGD_TABLE;

                flush_iopte_range(obj->dev, obj->pd_dma, offset, 1);
                dev_vdbg(obj->dev, "%s: a new pte:%p\n", __func__, iopte);
        } else {
                /* We raced, free the reduniovant table */
                iopte_free(obj, iopte, false);
        }

pte_ready:
        iopte = iopte_offset(iopgd, da);
        *pt_dma = virt_to_phys(iopte);
        dev_vdbg(obj->dev,
                 "%s: da:%08x pgd:%p *pgd:%08x pte:%p *pte:%08x\n",
                 __func__, da, iopgd, *iopgd, iopte, *iopte);

        return iopte;
}

static int iopgd_alloc_section(struct omap_iommu *obj, u32 da, u32 pa, u32 prot)
{
        u32 *iopgd = iopgd_offset(obj, da);
        unsigned long offset = iopgd_index(da) * sizeof(da);

        if ((da | pa) & ~IOSECTION_MASK) {
                dev_err(obj->dev, "%s: %08x:%08x should aligned on %08lx\n",
                        __func__, da, pa, IOSECTION_SIZE);
                return -EINVAL;
        }

        *iopgd = (pa & IOSECTION_MASK) | prot | IOPGD_SECTION;
        flush_iopte_range(obj->dev, obj->pd_dma, offset, 1);
        return 0;
}

static int iopgd_alloc_super(struct omap_iommu *obj, u32 da, u32 pa, u32 prot)
{
        u32 *iopgd = iopgd_offset(obj, da);
        unsigned long offset = iopgd_index(da) * sizeof(da);
        int i;

        if ((da | pa) & ~IOSUPER_MASK) {
                dev_err(obj->dev, "%s: %08x:%08x should aligned on %08lx\n",
                        __func__, da, pa, IOSUPER_SIZE);
                return -EINVAL;
        }

        for (i = 0; i < 16; i++)
                *(iopgd + i) = (pa & IOSUPER_MASK) | prot | IOPGD_SUPER;
        flush_iopte_range(obj->dev, obj->pd_dma, offset, 16);
        return 0;
}

static int iopte_alloc_page(struct omap_iommu *obj, u32 da, u32 pa, u32 prot)
{
        u32 *iopgd = iopgd_offset(obj, da);
        dma_addr_t pt_dma;
        u32 *iopte = iopte_alloc(obj, iopgd, &pt_dma, da);
        unsigned long offset = iopte_index(da) * sizeof(da);

        if (IS_ERR(iopte))
                return PTR_ERR(iopte);

        *iopte = (pa & IOPAGE_MASK) | prot | IOPTE_SMALL;
        flush_iopte_range(obj->dev, pt_dma, offset, 1);

        dev_vdbg(obj->dev, "%s: da:%08x pa:%08x pte:%p *pte:%08x\n",
                 __func__, da, pa, iopte, *iopte);

        return 0;
}

static int iopte_alloc_large(struct omap_iommu *obj, u32 da, u32 pa, u32 prot)
{
        u32 *iopgd = iopgd_offset(obj, da);
        dma_addr_t pt_dma;
        u32 *iopte = iopte_alloc(obj, iopgd, &pt_dma, da);
        unsigned long offset = iopte_index(da) * sizeof(da);
        int i;

        if ((da | pa) & ~IOLARGE_MASK) {
                dev_err(obj->dev, "%s: %08x:%08x should aligned on %08lx\n",
                        __func__, da, pa, IOLARGE_SIZE);
                return -EINVAL;
        }

        if (IS_ERR(iopte))
                return PTR_ERR(iopte);

        for (i = 0; i < 16; i++)
                *(iopte + i) = (pa & IOLARGE_MASK) | prot | IOPTE_LARGE;
        flush_iopte_range(obj->dev, pt_dma, offset, 16);
        return 0;
}

static int
iopgtable_store_entry_core(struct omap_iommu *obj, struct iotlb_entry *e)
{
        int (*fn)(struct omap_iommu *, u32, u32, u32);
        u32 prot;
        int err;

        if (!obj || !e)
                return -EINVAL;

        switch (e->pgsz) {
        case MMU_CAM_PGSZ_16M:
                fn = iopgd_alloc_super;
                break;
        case MMU_CAM_PGSZ_1M:
                fn = iopgd_alloc_section;
                break;
        case MMU_CAM_PGSZ_64K:
                fn = iopte_alloc_large;
                break;
        case MMU_CAM_PGSZ_4K:
                fn = iopte_alloc_page;
                break;
        default:
                fn = NULL;
                break;
        }

        if (WARN_ON(!fn))
                return -EINVAL;

        prot = get_iopte_attr(e);

        spin_lock(&obj->page_table_lock);
        err = fn(obj, e->da, e->pa, prot);
        spin_unlock(&obj->page_table_lock);

        return err;
}

/**
 * omap_iopgtable_store_entry - Make an iommu pte entry
 * @obj:        target iommu
 * @e:          an iommu tlb entry info
 **/
static int
omap_iopgtable_store_entry(struct omap_iommu *obj, struct iotlb_entry *e)
{
        int err;

        flush_iotlb_page(obj, e->da);
        err = iopgtable_store_entry_core(obj, e);
        if (!err)
                prefetch_iotlb_entry(obj, e);
        return err;
}

/**
 * iopgtable_lookup_entry - Lookup an iommu pte entry
 * @obj:        target iommu
 * @da:         iommu device virtual address
 * @ppgd:       iommu pgd entry pointer to be returned
 * @ppte:       iommu pte entry pointer to be returned
 **/
static void
iopgtable_lookup_entry(struct omap_iommu *obj, u32 da, u32 **ppgd, u32 **ppte)
{
        u32 *iopgd, *iopte = NULL;

        iopgd = iopgd_offset(obj, da);
        if (!*iopgd)
                goto out;

        if (iopgd_is_table(*iopgd))
                iopte = iopte_offset(iopgd, da);
out:
        *ppgd = iopgd;
        *ppte = iopte;
}

static size_t iopgtable_clear_entry_core(struct omap_iommu *obj, u32 da)
{
        size_t bytes;
        u32 *iopgd = iopgd_offset(obj, da);
        int nent = 1;
        dma_addr_t pt_dma;
        unsigned long pd_offset = iopgd_index(da) * sizeof(da);
        unsigned long pt_offset = iopte_index(da) * sizeof(da);

        if (!*iopgd)
                return 0;

        if (iopgd_is_table(*iopgd)) {
                int i;
                u32 *iopte = iopte_offset(iopgd, da);

                bytes = IOPTE_SIZE;
                if (*iopte & IOPTE_LARGE) {
                        nent *= 16;
                        /* rewind to the 1st entry */
                        iopte = iopte_offset(iopgd, (da & IOLARGE_MASK));
                }
                bytes *= nent;
                memset(iopte, 0, nent * sizeof(*iopte));
                pt_dma = virt_to_phys(iopte);
                flush_iopte_range(obj->dev, pt_dma, pt_offset, nent);

                /*
                 * do table walk to check if this table is necessary or not
                 */
                iopte = iopte_offset(iopgd, 0);
                for (i = 0; i < PTRS_PER_IOPTE; i++)
                        if (iopte[i])
                                goto out;

                iopte_free(obj, iopte, true);
                nent = 1; /* for the next L1 entry */
        } else {
                bytes = IOPGD_SIZE;
                if ((*iopgd & IOPGD_SUPER) == IOPGD_SUPER) {
                        nent *= 16;
                        /* rewind to the 1st entry */
                        iopgd = iopgd_offset(obj, (da & IOSUPER_MASK));
                }
                bytes *= nent;
        }
        memset(iopgd, 0, nent * sizeof(*iopgd));
        flush_iopte_range(obj->dev, obj->pd_dma, pd_offset, nent);
out:
        return bytes;
}

/**
 * iopgtable_clear_entry - Remove an iommu pte entry
 * @obj:        target iommu
 * @da:         iommu device virtual address
 **/
static size_t iopgtable_clear_entry(struct omap_iommu *obj, u32 da)
{
        size_t bytes;

        spin_lock(&obj->page_table_lock);

        bytes = iopgtable_clear_entry_core(obj, da);
        flush_iotlb_page(obj, da);

        spin_unlock(&obj->page_table_lock);

        return bytes;
}

static void iopgtable_clear_entry_all(struct omap_iommu *obj)
{
        unsigned long offset;
        int i;

        spin_lock(&obj->page_table_lock);

        for (i = 0; i < PTRS_PER_IOPGD; i++) {
                u32 da;
                u32 *iopgd;

                da = i << IOPGD_SHIFT;
                iopgd = iopgd_offset(obj, da);
                offset = iopgd_index(da) * sizeof(da);

                if (!*iopgd)
                        continue;

                if (iopgd_is_table(*iopgd))
                        iopte_free(obj, iopte_offset(iopgd, 0), true);

                *iopgd = 0;
                flush_iopte_range(obj->dev, obj->pd_dma, offset, 1);
        }

        flush_iotlb_all(obj);

        spin_unlock(&obj->page_table_lock);
}

/*
 *      Device IOMMU generic operations
 */
static irqreturn_t iommu_fault_handler(int irq, void *data)
{
        u32 da, errs;
        u32 *iopgd, *iopte;
        struct omap_iommu *obj = data;
        struct iommu_domain *domain = obj->domain;
        struct omap_iommu_domain *omap_domain = to_omap_domain(domain);

        if (!omap_domain->dev)
                return IRQ_NONE;

        errs = iommu_report_fault(obj, &da);
        if (errs == 0)
                return IRQ_HANDLED;

        /* Fault callback or TLB/PTE Dynamic loading */
        if (!report_iommu_fault(domain, obj->dev, da, 0))
                return IRQ_HANDLED;

        iommu_write_reg(obj, 0, MMU_IRQENABLE);

        iopgd = iopgd_offset(obj, da);

        if (!iopgd_is_table(*iopgd)) {
                dev_err(obj->dev, "%s: errs:0x%08x da:0x%08x pgd:0x%p *pgd:px%08x\n",
                        obj->name, errs, da, iopgd, *iopgd);
                return IRQ_NONE;
        }

        iopte = iopte_offset(iopgd, da);

        dev_err(obj->dev, "%s: errs:0x%08x da:0x%08x pgd:0x%p *pgd:0x%08x pte:0x%p *pte:0x%08x\n",
                obj->name, errs, da, iopgd, *iopgd, iopte, *iopte);

        return IRQ_NONE;
}

/**
 * omap_iommu_attach() - attach iommu device to an iommu domain
 * @obj:        target omap iommu device
 * @iopgd:      page table
 **/
static int omap_iommu_attach(struct omap_iommu *obj, u32 *iopgd)
{
        int err;

        spin_lock(&obj->iommu_lock);

        obj->pd_dma = dma_map_single(obj->dev, iopgd, IOPGD_TABLE_SIZE,
                                     DMA_TO_DEVICE);
        if (dma_mapping_error(obj->dev, obj->pd_dma)) {
                dev_err(obj->dev, "DMA map error for L1 table\n");
                err = -ENOMEM;
                goto out_err;
        }

        obj->iopgd = iopgd;
        err = iommu_enable(obj);
        if (err)
                goto out_err;
        flush_iotlb_all(obj);

        spin_unlock(&obj->iommu_lock);

        dev_dbg(obj->dev, "%s: %s\n", __func__, obj->name);

        return 0;

out_err:
        spin_unlock(&obj->iommu_lock);

        return err;
}

/**
 * omap_iommu_detach - release iommu device
 * @obj:        target iommu
 **/
static void omap_iommu_detach(struct omap_iommu *obj)
{
        if (!obj || IS_ERR(obj))
                return;

        spin_lock(&obj->iommu_lock);

        dma_unmap_single(obj->dev, obj->pd_dma, IOPGD_TABLE_SIZE,
                         DMA_TO_DEVICE);
        iommu_disable(obj);
        obj->pd_dma = 0;
        obj->iopgd = NULL;

        spin_unlock(&obj->iommu_lock);

        dev_dbg(obj->dev, "%s: %s\n", __func__, obj->name);
}

static bool omap_iommu_can_register(struct platform_device *pdev)
{
        struct device_node *np = pdev->dev.of_node;

        if (!of_device_is_compatible(np, "ti,dra7-dsp-iommu"))
                return true;

        /*
         * restrict IOMMU core registration only for processor-port MDMA MMUs
         * on DRA7 DSPs
         */
        if ((!strcmp(dev_name(&pdev->dev), "40d01000.mmu")) ||
            (!strcmp(dev_name(&pdev->dev), "41501000.mmu")))
                return true;

        return false;
}

static int omap_iommu_dra7_get_dsp_system_cfg(struct platform_device *pdev,
                                              struct omap_iommu *obj)
{
        struct device_node *np = pdev->dev.of_node;
        int ret;

        if (!of_device_is_compatible(np, "ti,dra7-dsp-iommu"))
                return 0;

        if (!of_property_read_bool(np, "ti,syscon-mmuconfig")) {
                dev_err(&pdev->dev, "ti,syscon-mmuconfig property is missing\n");
                return -EINVAL;
        }

        obj->syscfg =
                syscon_regmap_lookup_by_phandle(np, "ti,syscon-mmuconfig");
        if (IS_ERR(obj->syscfg)) {
                /* can fail with -EPROBE_DEFER */
                ret = PTR_ERR(obj->syscfg);
                return ret;
        }

        if (of_property_read_u32_index(np, "ti,syscon-mmuconfig", 1,
                                       &obj->id)) {
                dev_err(&pdev->dev, "couldn't get the IOMMU instance id within subsystem\n");
                return -EINVAL;
        }

        if (obj->id != 0 && obj->id != 1) {
                dev_err(&pdev->dev, "invalid IOMMU instance id\n");
                return -EINVAL;
        }

        return 0;
}

/*
 *      OMAP Device MMU(IOMMU) detection
 */
static int omap_iommu_probe(struct platform_device *pdev)
{
        int err = -ENODEV;
        int irq;
        struct omap_iommu *obj;
        struct resource *res;
        struct device_node *of = pdev->dev.of_node;

        if (!of) {
                pr_err("%s: only DT-based devices are supported\n", __func__);
                return -ENODEV;
        }

        obj = devm_kzalloc(&pdev->dev, sizeof(*obj) + MMU_REG_SIZE, GFP_KERNEL);
        if (!obj)
                return -ENOMEM;

        obj->name = dev_name(&pdev->dev);
        obj->nr_tlb_entries = 32;
        err = of_property_read_u32(of, "ti,#tlb-entries", &obj->nr_tlb_entries);
        if (err && err != -EINVAL)
                return err;
        if (obj->nr_tlb_entries != 32 && obj->nr_tlb_entries != 8)
                return -EINVAL;
        if (of_find_property(of, "ti,iommu-bus-err-back", NULL))
                obj->has_bus_err_back = MMU_GP_REG_BUS_ERR_BACK_EN;

        obj->dev = &pdev->dev;
        obj->ctx = (void *)obj + sizeof(*obj);

        spin_lock_init(&obj->iommu_lock);
        spin_lock_init(&obj->page_table_lock);

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        obj->regbase = devm_ioremap_resource(obj->dev, res);
        if (IS_ERR(obj->regbase))
                return PTR_ERR(obj->regbase);

        err = omap_iommu_dra7_get_dsp_system_cfg(pdev, obj);
        if (err)
                return err;

        irq = platform_get_irq(pdev, 0);
        if (irq < 0)
                return -ENODEV;

        err = devm_request_irq(obj->dev, irq, iommu_fault_handler, IRQF_SHARED,
                               dev_name(obj->dev), obj);
        if (err < 0)
                return err;
        platform_set_drvdata(pdev, obj);

        if (omap_iommu_can_register(pdev)) {
                obj->group = iommu_group_alloc();
                if (IS_ERR(obj->group))
                        return PTR_ERR(obj->group);

                err = iommu_device_sysfs_add(&obj->iommu, obj->dev, NULL,
                                             obj->name);
                if (err)
                        goto out_group;

                iommu_device_set_ops(&obj->iommu, &omap_iommu_ops);

                err = iommu_device_register(&obj->iommu);
                if (err)
                        goto out_sysfs;
        }

        pm_runtime_irq_safe(obj->dev);
        pm_runtime_enable(obj->dev);

        omap_iommu_debugfs_add(obj);

        dev_info(&pdev->dev, "%s registered\n", obj->name);

        return 0;

out_sysfs:
        iommu_device_sysfs_remove(&obj->iommu);
out_group:
        iommu_group_put(obj->group);
        return err;
}

static int omap_iommu_remove(struct platform_device *pdev)
{
        struct omap_iommu *obj = platform_get_drvdata(pdev);

        if (obj->group) {
                iommu_group_put(obj->group);
                obj->group = NULL;

                iommu_device_sysfs_remove(&obj->iommu);
                iommu_device_unregister(&obj->iommu);
        }

        omap_iommu_debugfs_remove(obj);

        pm_runtime_disable(obj->dev);

        dev_info(&pdev->dev, "%s removed\n", obj->name);
        return 0;
}

static const struct of_device_id omap_iommu_of_match[] = {
        { .compatible = "ti,omap2-iommu" },
        { .compatible = "ti,omap4-iommu" },
        { .compatible = "ti,dra7-iommu" },
        { .compatible = "ti,dra7-dsp-iommu" },
        {},
};

static struct platform_driver omap_iommu_driver = {
        .probe  = omap_iommu_probe,
        .remove = omap_iommu_remove,
        .driver = {
                .name   = "omap-iommu",
                .of_match_table = of_match_ptr(omap_iommu_of_match),
        },
};

static u32 iotlb_init_entry(struct iotlb_entry *e, u32 da, u32 pa, int pgsz)
{
        memset(e, 0, sizeof(*e));

        e->da           = da;
        e->pa           = pa;
        e->valid        = MMU_CAM_V;
        e->pgsz         = pgsz;
        e->endian       = MMU_RAM_ENDIAN_LITTLE;
        e->elsz         = MMU_RAM_ELSZ_8;
        e->mixed        = 0;

        return iopgsz_to_bytes(e->pgsz);
}

static int omap_iommu_map(struct iommu_domain *domain, unsigned long da,
                          phys_addr_t pa, size_t bytes, int prot)
{
        struct omap_iommu_domain *omap_domain = to_omap_domain(domain);
        struct device *dev = omap_domain->dev;
        struct omap_iommu_device *iommu;
        struct omap_iommu *oiommu;
        struct iotlb_entry e;
        int omap_pgsz;
        u32 ret = -EINVAL;
        int i;

        omap_pgsz = bytes_to_iopgsz(bytes);
        if (omap_pgsz < 0) {
                dev_err(dev, "invalid size to map: %d\n", bytes);
                return -EINVAL;
        }

        dev_dbg(dev, "mapping da 0x%lx to pa %pa size 0x%x\n", da, &pa, bytes);

        iotlb_init_entry(&e, da, pa, omap_pgsz);

        iommu = omap_domain->iommus;
        for (i = 0; i < omap_domain->num_iommus; i++, iommu++) {
                oiommu = iommu->iommu_dev;
                ret = omap_iopgtable_store_entry(oiommu, &e);
                if (ret) {
                        dev_err(dev, "omap_iopgtable_store_entry failed: %d\n",
                                ret);
                        break;
                }
        }

        if (ret) {
                while (i--) {
                        iommu--;
                        oiommu = iommu->iommu_dev;
                        iopgtable_clear_entry(oiommu, da);
                }
        }

        return ret;
}

static size_t omap_iommu_unmap(struct iommu_domain *domain, unsigned long da,
                               size_t size)
{
        struct omap_iommu_domain *omap_domain = to_omap_domain(domain);
        struct device *dev = omap_domain->dev;
        struct omap_iommu_device *iommu;
        struct omap_iommu *oiommu;
        bool error = false;
        size_t bytes = 0;
        int i;

        dev_dbg(dev, "unmapping da 0x%lx size %u\n", da, size);

        iommu = omap_domain->iommus;
        for (i = 0; i < omap_domain->num_iommus; i++, iommu++) {
                oiommu = iommu->iommu_dev;
                bytes = iopgtable_clear_entry(oiommu, da);
                if (!bytes)
                        error = true;
        }

        /*
         * simplify return - we are only checking if any of the iommus
         * reported an error, but not if all of them are unmapping the
         * same number of entries. This should not occur due to the
         * mirror programming.
         */
        return error ? 0 : bytes;
}

static int omap_iommu_count(struct device *dev)
{
        struct omap_iommu_arch_data *arch_data = dev->archdata.iommu;
        int count = 0;

        while (arch_data->iommu_dev) {
                count++;
                arch_data++;
        }

        return count;
}

/* caller should call cleanup if this function fails */
static int omap_iommu_attach_init(struct device *dev,
                                  struct omap_iommu_domain *odomain)
{
        struct omap_iommu_device *iommu;
        int i;

        odomain->num_iommus = omap_iommu_count(dev);
        if (!odomain->num_iommus)
                return -EINVAL;

        odomain->iommus = kcalloc(odomain->num_iommus, sizeof(*iommu),
                                  GFP_ATOMIC);
        if (!odomain->iommus)
                return -ENOMEM;

        iommu = odomain->iommus;
        for (i = 0; i < odomain->num_iommus; i++, iommu++) {
                iommu->pgtable = kzalloc(IOPGD_TABLE_SIZE, GFP_ATOMIC);
                if (!iommu->pgtable)
                        return -ENOMEM;

                /*
                 * should never fail, but please keep this around to ensure
                 * we keep the hardware happy
                 */
                if (WARN_ON(!IS_ALIGNED((long)iommu->pgtable,
                                        IOPGD_TABLE_SIZE)))
                        return -EINVAL;
        }

        return 0;
}

static void omap_iommu_detach_fini(struct omap_iommu_domain *odomain)
{
        int i;
        struct omap_iommu_device *iommu = odomain->iommus;

        for (i = 0; iommu && i < odomain->num_iommus; i++, iommu++)
                kfree(iommu->pgtable);

        kfree(odomain->iommus);
        odomain->num_iommus = 0;
        odomain->iommus = NULL;
}

static int
omap_iommu_attach_dev(struct iommu_domain *domain, struct device *dev)
{
        struct omap_iommu_domain *omap_domain = to_omap_domain(domain);
        struct omap_iommu_arch_data *arch_data = dev->archdata.iommu;
        struct omap_iommu_device *iommu;
        struct omap_iommu *oiommu;
        int ret = 0;
        int i;

        if (!arch_data || !arch_data->iommu_dev) {
                dev_err(dev, "device doesn't have an associated iommu\n");
                return -EINVAL;
        }

        spin_lock(&omap_domain->lock);

        /* only a single client device can be attached to a domain */
        if (omap_domain->dev) {
                dev_err(dev, "iommu domain is already attached\n");
                ret = -EBUSY;
                goto out;
        }

        ret = omap_iommu_attach_init(dev, omap_domain);
        if (ret) {
                dev_err(dev, "failed to allocate required iommu data %d\n",
                        ret);
                goto init_fail;
        }

        iommu = omap_domain->iommus;
        for (i = 0; i < omap_domain->num_iommus; i++, iommu++, arch_data++) {
                /* configure and enable the omap iommu */
                oiommu = arch_data->iommu_dev;
                ret = omap_iommu_attach(oiommu, iommu->pgtable);
                if (ret) {
                        dev_err(dev, "can't get omap iommu: %d\n", ret);
                        goto attach_fail;
                }

                oiommu->domain = domain;
                iommu->iommu_dev = oiommu;
        }

        omap_domain->dev = dev;

        goto out;

attach_fail:
        while (i--) {
                iommu--;
                arch_data--;
                oiommu = iommu->iommu_dev;
                omap_iommu_detach(oiommu);
                iommu->iommu_dev = NULL;
                oiommu->domain = NULL;
        }
init_fail:
        omap_iommu_detach_fini(omap_domain);
out:
        spin_unlock(&omap_domain->lock);
        return ret;
}

static void _omap_iommu_detach_dev(struct omap_iommu_domain *omap_domain,
                                   struct device *dev)
{
        struct omap_iommu_arch_data *arch_data = dev->archdata.iommu;
        struct omap_iommu_device *iommu = omap_domain->iommus;
        struct omap_iommu *oiommu;
        int i;

        if (!omap_domain->dev) {
                dev_err(dev, "domain has no attached device\n");
                return;
        }

        /* only a single device is supported per domain for now */
        if (omap_domain->dev != dev) {
                dev_err(dev, "invalid attached device\n");
                return;
        }

        /*
         * cleanup in the reverse order of attachment - this addresses
         * any h/w dependencies between multiple instances, if any
         */
        iommu += (omap_domain->num_iommus - 1);
        arch_data += (omap_domain->num_iommus - 1);
        for (i = 0; i < omap_domain->num_iommus; i++, iommu--, arch_data--) {
                oiommu = iommu->iommu_dev;
                iopgtable_clear_entry_all(oiommu);

                omap_iommu_detach(oiommu);
                iommu->iommu_dev = NULL;
                oiommu->domain = NULL;
        }

        omap_iommu_detach_fini(omap_domain);

        omap_domain->dev = NULL;
}

static void omap_iommu_detach_dev(struct iommu_domain *domain,
                                  struct device *dev)
{
        struct omap_iommu_domain *omap_domain = to_omap_domain(domain);

        spin_lock(&omap_domain->lock);
        _omap_iommu_detach_dev(omap_domain, dev);
        spin_unlock(&omap_domain->lock);
}

static struct iommu_domain *omap_iommu_domain_alloc(unsigned type)
{
        struct omap_iommu_domain *omap_domain;

        if (type != IOMMU_DOMAIN_UNMANAGED)
                return NULL;

        omap_domain = kzalloc(sizeof(*omap_domain), GFP_KERNEL);
        if (!omap_domain)
                return NULL;

        spin_lock_init(&omap_domain->lock);

        omap_domain->domain.geometry.aperture_start = 0;
        omap_domain->domain.geometry.aperture_end   = (1ULL << 32) - 1;
        omap_domain->domain.geometry.force_aperture = true;

        return &omap_domain->domain;
}

static void omap_iommu_domain_free(struct iommu_domain *domain)
{
        struct omap_iommu_domain *omap_domain = to_omap_domain(domain);

        /*
         * An iommu device is still attached
         * (currently, only one device can be attached) ?
         */
        if (omap_domain->dev)
                _omap_iommu_detach_dev(omap_domain, omap_domain->dev);

        kfree(omap_domain);
}

static phys_addr_t omap_iommu_iova_to_phys(struct iommu_domain *domain,
                                           dma_addr_t da)
{
        struct omap_iommu_domain *omap_domain = to_omap_domain(domain);
        struct omap_iommu_device *iommu = omap_domain->iommus;
        struct omap_iommu *oiommu = iommu->iommu_dev;
        struct device *dev = oiommu->dev;
        u32 *pgd, *pte;
        phys_addr_t ret = 0;

        /*
         * all the iommus within the domain will have identical programming,
         * so perform the lookup using just the first iommu
         */
        iopgtable_lookup_entry(oiommu, da, &pgd, &pte);

        if (pte) {
                if (iopte_is_small(*pte))
                        ret = omap_iommu_translate(*pte, da, IOPTE_MASK);
                else if (iopte_is_large(*pte))
                        ret = omap_iommu_translate(*pte, da, IOLARGE_MASK);
                else
                        dev_err(dev, "bogus pte 0x%x, da 0x%llx", *pte,
                                (unsigned long long)da);
        } else {
                if (iopgd_is_section(*pgd))
                        ret = omap_iommu_translate(*pgd, da, IOSECTION_MASK);
                else if (iopgd_is_super(*pgd))
                        ret = omap_iommu_translate(*pgd, da, IOSUPER_MASK);
                else
                        dev_err(dev, "bogus pgd 0x%x, da 0x%llx", *pgd,
                                (unsigned long long)da);
        }

        return ret;
}

static int omap_iommu_add_device(struct device *dev)
{
        struct omap_iommu_arch_data *arch_data, *tmp;
        struct omap_iommu *oiommu;
        struct iommu_group *group;
        struct device_node *np;
        struct platform_device *pdev;
        int num_iommus, i;
        int ret;

        /*
         * Allocate the archdata iommu structure for DT-based devices.
         *
         * TODO: Simplify this when removing non-DT support completely from the
         * IOMMU users.
         */
        if (!dev->of_node)
                return 0;

        /*
         * retrieve the count of IOMMU nodes using phandle size as element size
         * since #iommu-cells = 0 for OMAP
         */
        num_iommus = of_property_count_elems_of_size(dev->of_node, "iommus",
                                                     sizeof(phandle));
        if (num_iommus < 0)
                return 0;

        arch_data = kzalloc((num_iommus + 1) * sizeof(*arch_data), GFP_KERNEL);
        if (!arch_data)
                return -ENOMEM;

        for (i = 0, tmp = arch_data; i < num_iommus; i++, tmp++) {
                np = of_parse_phandle(dev->of_node, "iommus", i);
                if (!np) {
                        kfree(arch_data);
                        return -EINVAL;
                }

                pdev = of_find_device_by_node(np);
                if (WARN_ON(!pdev)) {
                        of_node_put(np);
                        kfree(arch_data);
                        return -EINVAL;
                }

                oiommu = platform_get_drvdata(pdev);
                if (!oiommu) {
                        of_node_put(np);
                        kfree(arch_data);
                        return -EINVAL;
                }

                tmp->iommu_dev = oiommu;

                of_node_put(np);
        }

        /*
         * use the first IOMMU alone for the sysfs device linking.
         * TODO: Evaluate if a single iommu_group needs to be
         * maintained for both IOMMUs
         */
        oiommu = arch_data->iommu_dev;
        ret = iommu_device_link(&oiommu->iommu, dev);
        if (ret) {
                kfree(arch_data);
                return ret;
        }

        dev->archdata.iommu = arch_data;

        /*
         * IOMMU group initialization calls into omap_iommu_device_group, which
         * needs a valid dev->archdata.iommu pointer
         */
        group = iommu_group_get_for_dev(dev);
        if (IS_ERR(group)) {
                iommu_device_unlink(&oiommu->iommu, dev);
                dev->archdata.iommu = NULL;
                kfree(arch_data);
                return PTR_ERR(group);
        }
        iommu_group_put(group);

        return 0;
}

static void omap_iommu_remove_device(struct device *dev)
{
        struct omap_iommu_arch_data *arch_data = dev->archdata.iommu;

        if (!dev->of_node || !arch_data)
                return;

        iommu_device_unlink(&arch_data->iommu_dev->iommu, dev);
        iommu_group_remove_device(dev);

        dev->archdata.iommu = NULL;
        kfree(arch_data);

}

static struct iommu_group *omap_iommu_device_group(struct device *dev)
{
        struct omap_iommu_arch_data *arch_data = dev->archdata.iommu;
        struct iommu_group *group = ERR_PTR(-EINVAL);

        if (arch_data->iommu_dev)
                group = arch_data->iommu_dev->group;

        return group;
}

static const struct iommu_ops omap_iommu_ops = {
        .domain_alloc   = omap_iommu_domain_alloc,
        .domain_free    = omap_iommu_domain_free,
        .attach_dev     = omap_iommu_attach_dev,
        .detach_dev     = omap_iommu_detach_dev,
        .map            = omap_iommu_map,
        .unmap          = omap_iommu_unmap,
        .map_sg         = default_iommu_map_sg,
        .iova_to_phys   = omap_iommu_iova_to_phys,
        .add_device     = omap_iommu_add_device,
        .remove_device  = omap_iommu_remove_device,
        .device_group   = omap_iommu_device_group,
        .pgsize_bitmap  = OMAP_IOMMU_PGSIZES,
};

static int __init omap_iommu_init(void)
{
        struct kmem_cache *p;
        const unsigned long flags = SLAB_HWCACHE_ALIGN;
        size_t align = 1 << 10; /* L2 pagetable alignement */
        struct device_node *np;
        int ret;

        np = of_find_matching_node(NULL, omap_iommu_of_match);
        if (!np)
                return 0;

        of_node_put(np);

        p = kmem_cache_create("iopte_cache", IOPTE_TABLE_SIZE, align, flags,
                              NULL);
        if (!p)
                return -ENOMEM;
        iopte_cachep = p;

        omap_iommu_debugfs_init();

        ret = platform_driver_register(&omap_iommu_driver);
        if (ret) {
                pr_err("%s: failed to register driver\n", __func__);
                goto fail_driver;
        }

        ret = bus_set_iommu(&platform_bus_type, &omap_iommu_ops);
        if (ret)
                goto fail_bus;

        return 0;

fail_bus:
        platform_driver_unregister(&omap_iommu_driver);
fail_driver:
        kmem_cache_destroy(iopte_cachep);
        return ret;
}
subsys_initcall(omap_iommu_init);
/* must be ready before omap3isp is probed */