Merge tag 'leds_for_4.14' of git://git.kernel.org/pub/scm/linux/kernel/git/j.anaszews...

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

/*
 * IPMMU VMSA
 *
 * Copyright (C) 2014 Renesas Electronics Corporation
 *
 * 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; version 2 of the License.
 */

#include <linux/bitmap.h>
#include <linux/delay.h>
#include <linux/dma-iommu.h>
#include <linux/dma-mapping.h>
#include <linux/err.h>
#include <linux/export.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/iommu.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/sizes.h>
#include <linux/slab.h>

#if defined(CONFIG_ARM) && !defined(CONFIG_IOMMU_DMA)
#include <asm/dma-iommu.h>
#include <asm/pgalloc.h>
#endif

#include "io-pgtable.h"

#define IPMMU_CTX_MAX 1

struct ipmmu_vmsa_device {
        struct device *dev;
        void __iomem *base;
        struct list_head list;

        unsigned int num_utlbs;
        spinlock_t lock;                        /* Protects ctx and domains[] */
        DECLARE_BITMAP(ctx, IPMMU_CTX_MAX);
        struct ipmmu_vmsa_domain *domains[IPMMU_CTX_MAX];

        struct dma_iommu_mapping *mapping;
};

struct ipmmu_vmsa_domain {
        struct ipmmu_vmsa_device *mmu;
        struct iommu_domain io_domain;

        struct io_pgtable_cfg cfg;
        struct io_pgtable_ops *iop;

        unsigned int context_id;
        spinlock_t lock;                        /* Protects mappings */
};

struct ipmmu_vmsa_iommu_priv {
        struct ipmmu_vmsa_device *mmu;
        unsigned int *utlbs;
        unsigned int num_utlbs;
        struct device *dev;
        struct list_head list;
};

static DEFINE_SPINLOCK(ipmmu_devices_lock);
static LIST_HEAD(ipmmu_devices);

static struct ipmmu_vmsa_domain *to_vmsa_domain(struct iommu_domain *dom)
{
        return container_of(dom, struct ipmmu_vmsa_domain, io_domain);
}


static struct ipmmu_vmsa_iommu_priv *to_priv(struct device *dev)
{
#if defined(CONFIG_ARM)
        return dev->archdata.iommu;
#else
        return dev->iommu_fwspec->iommu_priv;
#endif
}
static void set_priv(struct device *dev, struct ipmmu_vmsa_iommu_priv *p)
{
#if defined(CONFIG_ARM)
        dev->archdata.iommu = p;
#else
        dev->iommu_fwspec->iommu_priv = p;
#endif
}

#define TLB_LOOP_TIMEOUT                100     /* 100us */

/* -----------------------------------------------------------------------------
 * Registers Definition
 */

#define IM_NS_ALIAS_OFFSET              0x800

#define IM_CTX_SIZE                     0x40

#define IMCTR                           0x0000
#define IMCTR_TRE                       (1 << 17)
#define IMCTR_AFE                       (1 << 16)
#define IMCTR_RTSEL_MASK                (3 << 4)
#define IMCTR_RTSEL_SHIFT               4
#define IMCTR_TREN                      (1 << 3)
#define IMCTR_INTEN                     (1 << 2)
#define IMCTR_FLUSH                     (1 << 1)
#define IMCTR_MMUEN                     (1 << 0)

#define IMCAAR                          0x0004

#define IMTTBCR                         0x0008
#define IMTTBCR_EAE                     (1 << 31)
#define IMTTBCR_PMB                     (1 << 30)
#define IMTTBCR_SH1_NON_SHAREABLE       (0 << 28)
#define IMTTBCR_SH1_OUTER_SHAREABLE     (2 << 28)
#define IMTTBCR_SH1_INNER_SHAREABLE     (3 << 28)
#define IMTTBCR_SH1_MASK                (3 << 28)
#define IMTTBCR_ORGN1_NC                (0 << 26)
#define IMTTBCR_ORGN1_WB_WA             (1 << 26)
#define IMTTBCR_ORGN1_WT                (2 << 26)
#define IMTTBCR_ORGN1_WB                (3 << 26)
#define IMTTBCR_ORGN1_MASK              (3 << 26)
#define IMTTBCR_IRGN1_NC                (0 << 24)
#define IMTTBCR_IRGN1_WB_WA             (1 << 24)
#define IMTTBCR_IRGN1_WT                (2 << 24)
#define IMTTBCR_IRGN1_WB                (3 << 24)
#define IMTTBCR_IRGN1_MASK              (3 << 24)
#define IMTTBCR_TSZ1_MASK               (7 << 16)
#define IMTTBCR_TSZ1_SHIFT              16
#define IMTTBCR_SH0_NON_SHAREABLE       (0 << 12)
#define IMTTBCR_SH0_OUTER_SHAREABLE     (2 << 12)
#define IMTTBCR_SH0_INNER_SHAREABLE     (3 << 12)
#define IMTTBCR_SH0_MASK                (3 << 12)
#define IMTTBCR_ORGN0_NC                (0 << 10)
#define IMTTBCR_ORGN0_WB_WA             (1 << 10)
#define IMTTBCR_ORGN0_WT                (2 << 10)
#define IMTTBCR_ORGN0_WB                (3 << 10)
#define IMTTBCR_ORGN0_MASK              (3 << 10)
#define IMTTBCR_IRGN0_NC                (0 << 8)
#define IMTTBCR_IRGN0_WB_WA             (1 << 8)
#define IMTTBCR_IRGN0_WT                (2 << 8)
#define IMTTBCR_IRGN0_WB                (3 << 8)
#define IMTTBCR_IRGN0_MASK              (3 << 8)
#define IMTTBCR_SL0_LVL_2               (0 << 4)
#define IMTTBCR_SL0_LVL_1               (1 << 4)
#define IMTTBCR_TSZ0_MASK               (7 << 0)
#define IMTTBCR_TSZ0_SHIFT              O

#define IMBUSCR                         0x000c
#define IMBUSCR_DVM                     (1 << 2)
#define IMBUSCR_BUSSEL_SYS              (0 << 0)
#define IMBUSCR_BUSSEL_CCI              (1 << 0)
#define IMBUSCR_BUSSEL_IMCAAR           (2 << 0)
#define IMBUSCR_BUSSEL_CCI_IMCAAR       (3 << 0)
#define IMBUSCR_BUSSEL_MASK             (3 << 0)

#define IMTTLBR0                        0x0010
#define IMTTUBR0                        0x0014
#define IMTTLBR1                        0x0018
#define IMTTUBR1                        0x001c

#define IMSTR                           0x0020
#define IMSTR_ERRLVL_MASK               (3 << 12)
#define IMSTR_ERRLVL_SHIFT              12
#define IMSTR_ERRCODE_TLB_FORMAT        (1 << 8)
#define IMSTR_ERRCODE_ACCESS_PERM       (4 << 8)
#define IMSTR_ERRCODE_SECURE_ACCESS     (5 << 8)
#define IMSTR_ERRCODE_MASK              (7 << 8)
#define IMSTR_MHIT                      (1 << 4)
#define IMSTR_ABORT                     (1 << 2)
#define IMSTR_PF                        (1 << 1)
#define IMSTR_TF                        (1 << 0)

#define IMMAIR0                         0x0028
#define IMMAIR1                         0x002c
#define IMMAIR_ATTR_MASK                0xff
#define IMMAIR_ATTR_DEVICE              0x04
#define IMMAIR_ATTR_NC                  0x44
#define IMMAIR_ATTR_WBRWA               0xff
#define IMMAIR_ATTR_SHIFT(n)            ((n) << 3)
#define IMMAIR_ATTR_IDX_NC              0
#define IMMAIR_ATTR_IDX_WBRWA           1
#define IMMAIR_ATTR_IDX_DEV             2

#define IMEAR                           0x0030

#define IMPCTR                          0x0200
#define IMPSTR                          0x0208
#define IMPEAR                          0x020c
#define IMPMBA(n)                       (0x0280 + ((n) * 4))
#define IMPMBD(n)                       (0x02c0 + ((n) * 4))

#define IMUCTR(n)                       (0x0300 + ((n) * 16))
#define IMUCTR_FIXADDEN                 (1 << 31)
#define IMUCTR_FIXADD_MASK              (0xff << 16)
#define IMUCTR_FIXADD_SHIFT             16
#define IMUCTR_TTSEL_MMU(n)             ((n) << 4)
#define IMUCTR_TTSEL_PMB                (8 << 4)
#define IMUCTR_TTSEL_MASK               (15 << 4)
#define IMUCTR_FLUSH                    (1 << 1)
#define IMUCTR_MMUEN                    (1 << 0)

#define IMUASID(n)                      (0x0308 + ((n) * 16))
#define IMUASID_ASID8_MASK              (0xff << 8)
#define IMUASID_ASID8_SHIFT             8
#define IMUASID_ASID0_MASK              (0xff << 0)
#define IMUASID_ASID0_SHIFT             0

/* -----------------------------------------------------------------------------
 * Read/Write Access
 */

static u32 ipmmu_read(struct ipmmu_vmsa_device *mmu, unsigned int offset)
{
        return ioread32(mmu->base + offset);
}

static void ipmmu_write(struct ipmmu_vmsa_device *mmu, unsigned int offset,
                        u32 data)
{
        iowrite32(data, mmu->base + offset);
}

static u32 ipmmu_ctx_read(struct ipmmu_vmsa_domain *domain, unsigned int reg)
{
        return ipmmu_read(domain->mmu, domain->context_id * IM_CTX_SIZE + reg);
}

static void ipmmu_ctx_write(struct ipmmu_vmsa_domain *domain, unsigned int reg,
                            u32 data)
{
        ipmmu_write(domain->mmu, domain->context_id * IM_CTX_SIZE + reg, data);
}

/* -----------------------------------------------------------------------------
 * TLB and microTLB Management
 */

/* Wait for any pending TLB invalidations to complete */
static void ipmmu_tlb_sync(struct ipmmu_vmsa_domain *domain)
{
        unsigned int count = 0;

        while (ipmmu_ctx_read(domain, IMCTR) & IMCTR_FLUSH) {
                cpu_relax();
                if (++count == TLB_LOOP_TIMEOUT) {
                        dev_err_ratelimited(domain->mmu->dev,
                        "TLB sync timed out -- MMU may be deadlocked\n");
                        return;
                }
                udelay(1);
        }
}

static void ipmmu_tlb_invalidate(struct ipmmu_vmsa_domain *domain)
{
        u32 reg;

        reg = ipmmu_ctx_read(domain, IMCTR);
        reg |= IMCTR_FLUSH;
        ipmmu_ctx_write(domain, IMCTR, reg);

        ipmmu_tlb_sync(domain);
}

/*
 * Enable MMU translation for the microTLB.
 */
static void ipmmu_utlb_enable(struct ipmmu_vmsa_domain *domain,
                              unsigned int utlb)
{
        struct ipmmu_vmsa_device *mmu = domain->mmu;

        /*
         * TODO: Reference-count the microTLB as several bus masters can be
         * connected to the same microTLB.
         */

        /* TODO: What should we set the ASID to ? */
        ipmmu_write(mmu, IMUASID(utlb), 0);
        /* TODO: Do we need to flush the microTLB ? */
        ipmmu_write(mmu, IMUCTR(utlb),
                    IMUCTR_TTSEL_MMU(domain->context_id) | IMUCTR_FLUSH |
                    IMUCTR_MMUEN);
}

/*
 * Disable MMU translation for the microTLB.
 */
static void ipmmu_utlb_disable(struct ipmmu_vmsa_domain *domain,
                               unsigned int utlb)
{
        struct ipmmu_vmsa_device *mmu = domain->mmu;

        ipmmu_write(mmu, IMUCTR(utlb), 0);
}

static void ipmmu_tlb_flush_all(void *cookie)
{
        struct ipmmu_vmsa_domain *domain = cookie;

        ipmmu_tlb_invalidate(domain);
}

static void ipmmu_tlb_add_flush(unsigned long iova, size_t size,
                                size_t granule, bool leaf, void *cookie)
{
        /* The hardware doesn't support selective TLB flush. */
}

static struct iommu_gather_ops ipmmu_gather_ops = {
        .tlb_flush_all = ipmmu_tlb_flush_all,
        .tlb_add_flush = ipmmu_tlb_add_flush,
        .tlb_sync = ipmmu_tlb_flush_all,
};

/* -----------------------------------------------------------------------------
 * Domain/Context Management
 */

static int ipmmu_domain_allocate_context(struct ipmmu_vmsa_device *mmu,
                                         struct ipmmu_vmsa_domain *domain)
{
        unsigned long flags;
        int ret;

        spin_lock_irqsave(&mmu->lock, flags);

        ret = find_first_zero_bit(mmu->ctx, IPMMU_CTX_MAX);
        if (ret != IPMMU_CTX_MAX) {
                mmu->domains[ret] = domain;
                set_bit(ret, mmu->ctx);
        }

        spin_unlock_irqrestore(&mmu->lock, flags);

        return ret;
}

static int ipmmu_domain_init_context(struct ipmmu_vmsa_domain *domain)
{
        u64 ttbr;
        int ret;

        /*
         * Allocate the page table operations.
         *
         * VMSA states in section B3.6.3 "Control of Secure or Non-secure memory
         * access, Long-descriptor format" that the NStable bit being set in a
         * table descriptor will result in the NStable and NS bits of all child
         * entries being ignored and considered as being set. The IPMMU seems
         * not to comply with this, as it generates a secure access page fault
         * if any of the NStable and NS bits isn't set when running in
         * non-secure mode.
         */
        domain->cfg.quirks = IO_PGTABLE_QUIRK_ARM_NS;
        domain->cfg.pgsize_bitmap = SZ_1G | SZ_2M | SZ_4K;
        domain->cfg.ias = 32;
        domain->cfg.oas = 40;
        domain->cfg.tlb = &ipmmu_gather_ops;
        domain->io_domain.geometry.aperture_end = DMA_BIT_MASK(32);
        domain->io_domain.geometry.force_aperture = true;
        /*
         * TODO: Add support for coherent walk through CCI with DVM and remove
         * cache handling. For now, delegate it to the io-pgtable code.
         */
        domain->cfg.iommu_dev = domain->mmu->dev;

        domain->iop = alloc_io_pgtable_ops(ARM_32_LPAE_S1, &domain->cfg,
                                           domain);
        if (!domain->iop)
                return -EINVAL;

        /*
         * Find an unused context.
         */
        ret = ipmmu_domain_allocate_context(domain->mmu, domain);
        if (ret == IPMMU_CTX_MAX) {
                free_io_pgtable_ops(domain->iop);
                return -EBUSY;
        }

        domain->context_id = ret;

        /* TTBR0 */
        ttbr = domain->cfg.arm_lpae_s1_cfg.ttbr[0];
        ipmmu_ctx_write(domain, IMTTLBR0, ttbr);
        ipmmu_ctx_write(domain, IMTTUBR0, ttbr >> 32);

        /*
         * TTBCR
         * We use long descriptors with inner-shareable WBWA tables and allocate
         * the whole 32-bit VA space to TTBR0.
         */
        ipmmu_ctx_write(domain, IMTTBCR, IMTTBCR_EAE |
                        IMTTBCR_SH0_INNER_SHAREABLE | IMTTBCR_ORGN0_WB_WA |
                        IMTTBCR_IRGN0_WB_WA | IMTTBCR_SL0_LVL_1);

        /* MAIR0 */
        ipmmu_ctx_write(domain, IMMAIR0, domain->cfg.arm_lpae_s1_cfg.mair[0]);

        /* IMBUSCR */
        ipmmu_ctx_write(domain, IMBUSCR,
                        ipmmu_ctx_read(domain, IMBUSCR) &
                        ~(IMBUSCR_DVM | IMBUSCR_BUSSEL_MASK));

        /*
         * IMSTR
         * Clear all interrupt flags.
         */
        ipmmu_ctx_write(domain, IMSTR, ipmmu_ctx_read(domain, IMSTR));

        /*
         * IMCTR
         * Enable the MMU and interrupt generation. The long-descriptor
         * translation table format doesn't use TEX remapping. Don't enable AF
         * software management as we have no use for it. Flush the TLB as
         * required when modifying the context registers.
         */
        ipmmu_ctx_write(domain, IMCTR, IMCTR_INTEN | IMCTR_FLUSH | IMCTR_MMUEN);

        return 0;
}

static void ipmmu_domain_free_context(struct ipmmu_vmsa_device *mmu,
                                      unsigned int context_id)
{
        unsigned long flags;

        spin_lock_irqsave(&mmu->lock, flags);

        clear_bit(context_id, mmu->ctx);
        mmu->domains[context_id] = NULL;

        spin_unlock_irqrestore(&mmu->lock, flags);
}

static void ipmmu_domain_destroy_context(struct ipmmu_vmsa_domain *domain)
{
        /*
         * Disable the context. Flush the TLB as required when modifying the
         * context registers.
         *
         * TODO: Is TLB flush really needed ?
         */
        ipmmu_ctx_write(domain, IMCTR, IMCTR_FLUSH);
        ipmmu_tlb_sync(domain);
        ipmmu_domain_free_context(domain->mmu, domain->context_id);
}

/* -----------------------------------------------------------------------------
 * Fault Handling
 */

static irqreturn_t ipmmu_domain_irq(struct ipmmu_vmsa_domain *domain)
{
        const u32 err_mask = IMSTR_MHIT | IMSTR_ABORT | IMSTR_PF | IMSTR_TF;
        struct ipmmu_vmsa_device *mmu = domain->mmu;
        u32 status;
        u32 iova;

        status = ipmmu_ctx_read(domain, IMSTR);
        if (!(status & err_mask))
                return IRQ_NONE;

        iova = ipmmu_ctx_read(domain, IMEAR);

        /*
         * Clear the error status flags. Unlike traditional interrupt flag
         * registers that must be cleared by writing 1, this status register
         * seems to require 0. The error address register must be read before,
         * otherwise its value will be 0.
         */
        ipmmu_ctx_write(domain, IMSTR, 0);

        /* Log fatal errors. */
        if (status & IMSTR_MHIT)
                dev_err_ratelimited(mmu->dev, "Multiple TLB hits @0x%08x\n",
                                    iova);
        if (status & IMSTR_ABORT)
                dev_err_ratelimited(mmu->dev, "Page Table Walk Abort @0x%08x\n",
                                    iova);

        if (!(status & (IMSTR_PF | IMSTR_TF)))
                return IRQ_NONE;

        /*
         * Try to handle page faults and translation faults.
         *
         * TODO: We need to look up the faulty device based on the I/O VA. Use
         * the IOMMU device for now.
         */
        if (!report_iommu_fault(&domain->io_domain, mmu->dev, iova, 0))
                return IRQ_HANDLED;

        dev_err_ratelimited(mmu->dev,
                            "Unhandled fault: status 0x%08x iova 0x%08x\n",
                            status, iova);

        return IRQ_HANDLED;
}

static irqreturn_t ipmmu_irq(int irq, void *dev)
{
        struct ipmmu_vmsa_device *mmu = dev;
        irqreturn_t status = IRQ_NONE;
        unsigned int i;
        unsigned long flags;

        spin_lock_irqsave(&mmu->lock, flags);

        /*
         * Check interrupts for all active contexts.
         */
        for (i = 0; i < IPMMU_CTX_MAX; i++) {
                if (!mmu->domains[i])
                        continue;
                if (ipmmu_domain_irq(mmu->domains[i]) == IRQ_HANDLED)
                        status = IRQ_HANDLED;
        }

        spin_unlock_irqrestore(&mmu->lock, flags);

        return status;
}

/* -----------------------------------------------------------------------------
 * IOMMU Operations
 */

static struct iommu_domain *__ipmmu_domain_alloc(unsigned type)
{
        struct ipmmu_vmsa_domain *domain;

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

        spin_lock_init(&domain->lock);

        return &domain->io_domain;
}

static void ipmmu_domain_free(struct iommu_domain *io_domain)
{
        struct ipmmu_vmsa_domain *domain = to_vmsa_domain(io_domain);

        /*
         * Free the domain resources. We assume that all devices have already
         * been detached.
         */
        ipmmu_domain_destroy_context(domain);
        free_io_pgtable_ops(domain->iop);
        kfree(domain);
}

static int ipmmu_attach_device(struct iommu_domain *io_domain,
                               struct device *dev)
{
        struct ipmmu_vmsa_iommu_priv *priv = to_priv(dev);
        struct ipmmu_vmsa_device *mmu = priv->mmu;
        struct ipmmu_vmsa_domain *domain = to_vmsa_domain(io_domain);
        unsigned long flags;
        unsigned int i;
        int ret = 0;

        if (!mmu) {
                dev_err(dev, "Cannot attach to IPMMU\n");
                return -ENXIO;
        }

        spin_lock_irqsave(&domain->lock, flags);

        if (!domain->mmu) {
                /* The domain hasn't been used yet, initialize it. */
                domain->mmu = mmu;
                ret = ipmmu_domain_init_context(domain);
        } else if (domain->mmu != mmu) {
                /*
                 * Something is wrong, we can't attach two devices using
                 * different IOMMUs to the same domain.
                 */
                dev_err(dev, "Can't attach IPMMU %s to domain on IPMMU %s\n",
                        dev_name(mmu->dev), dev_name(domain->mmu->dev));
                ret = -EINVAL;
        } else
                dev_info(dev, "Reusing IPMMU context %u\n", domain->context_id);

        spin_unlock_irqrestore(&domain->lock, flags);

        if (ret < 0)
                return ret;

        for (i = 0; i < priv->num_utlbs; ++i)
                ipmmu_utlb_enable(domain, priv->utlbs[i]);

        return 0;
}

static void ipmmu_detach_device(struct iommu_domain *io_domain,
                                struct device *dev)
{
        struct ipmmu_vmsa_iommu_priv *priv = to_priv(dev);
        struct ipmmu_vmsa_domain *domain = to_vmsa_domain(io_domain);
        unsigned int i;

        for (i = 0; i < priv->num_utlbs; ++i)
                ipmmu_utlb_disable(domain, priv->utlbs[i]);

        /*
         * TODO: Optimize by disabling the context when no device is attached.
         */
}

static int ipmmu_map(struct iommu_domain *io_domain, unsigned long iova,
                     phys_addr_t paddr, size_t size, int prot)
{
        struct ipmmu_vmsa_domain *domain = to_vmsa_domain(io_domain);

        if (!domain)
                return -ENODEV;

        return domain->iop->map(domain->iop, iova, paddr, size, prot);
}

static size_t ipmmu_unmap(struct iommu_domain *io_domain, unsigned long iova,
                          size_t size)
{
        struct ipmmu_vmsa_domain *domain = to_vmsa_domain(io_domain);

        return domain->iop->unmap(domain->iop, iova, size);
}

static phys_addr_t ipmmu_iova_to_phys(struct iommu_domain *io_domain,
                                      dma_addr_t iova)
{
        struct ipmmu_vmsa_domain *domain = to_vmsa_domain(io_domain);

        /* TODO: Is locking needed ? */

        return domain->iop->iova_to_phys(domain->iop, iova);
}

static int ipmmu_find_utlbs(struct ipmmu_vmsa_device *mmu, struct device *dev,
                            unsigned int *utlbs, unsigned int num_utlbs)
{
        unsigned int i;

        for (i = 0; i < num_utlbs; ++i) {
                struct of_phandle_args args;
                int ret;

                ret = of_parse_phandle_with_args(dev->of_node, "iommus",
                                                 "#iommu-cells", i, &args);
                if (ret < 0)
                        return ret;

                of_node_put(args.np);

                if (args.np != mmu->dev->of_node || args.args_count != 1)
                        return -EINVAL;

                utlbs[i] = args.args[0];
        }

        return 0;
}

static int ipmmu_init_platform_device(struct device *dev)
{
        struct ipmmu_vmsa_iommu_priv *priv;
        struct ipmmu_vmsa_device *mmu;
        unsigned int *utlbs;
        unsigned int i;
        int num_utlbs;
        int ret = -ENODEV;

        /* Find the master corresponding to the device. */

        num_utlbs = of_count_phandle_with_args(dev->of_node, "iommus",
                                               "#iommu-cells");
        if (num_utlbs < 0)
                return -ENODEV;

        utlbs = kcalloc(num_utlbs, sizeof(*utlbs), GFP_KERNEL);
        if (!utlbs)
                return -ENOMEM;

        spin_lock(&ipmmu_devices_lock);

        list_for_each_entry(mmu, &ipmmu_devices, list) {
                ret = ipmmu_find_utlbs(mmu, dev, utlbs, num_utlbs);
                if (!ret) {
                        /*
                         * TODO Take a reference to the MMU to protect
                         * against device removal.
                         */
                        break;
                }
        }

        spin_unlock(&ipmmu_devices_lock);

        if (ret < 0)
                goto error;

        for (i = 0; i < num_utlbs; ++i) {
                if (utlbs[i] >= mmu->num_utlbs) {
                        ret = -EINVAL;
                        goto error;
                }
        }

        priv = kzalloc(sizeof(*priv), GFP_KERNEL);
        if (!priv) {
                ret = -ENOMEM;
                goto error;
        }

        priv->mmu = mmu;
        priv->utlbs = utlbs;
        priv->num_utlbs = num_utlbs;
        priv->dev = dev;
        set_priv(dev, priv);
        return 0;

error:
        kfree(utlbs);
        return ret;
}

#if defined(CONFIG_ARM) && !defined(CONFIG_IOMMU_DMA)

static struct iommu_domain *ipmmu_domain_alloc(unsigned type)
{
        if (type != IOMMU_DOMAIN_UNMANAGED)
                return NULL;

        return __ipmmu_domain_alloc(type);
}

static int ipmmu_add_device(struct device *dev)
{
        struct ipmmu_vmsa_device *mmu = NULL;
        struct iommu_group *group;
        int ret;

        if (to_priv(dev)) {
                dev_warn(dev, "IOMMU driver already assigned to device %s\n",
                         dev_name(dev));
                return -EINVAL;
        }

        /* Create a device group and add the device to it. */
        group = iommu_group_alloc();
        if (IS_ERR(group)) {
                dev_err(dev, "Failed to allocate IOMMU group\n");
                ret = PTR_ERR(group);
                goto error;
        }

        ret = iommu_group_add_device(group, dev);
        iommu_group_put(group);

        if (ret < 0) {
                dev_err(dev, "Failed to add device to IPMMU group\n");
                group = NULL;
                goto error;
        }

        ret = ipmmu_init_platform_device(dev);
        if (ret < 0)
                goto error;

        /*
         * Create the ARM mapping, used by the ARM DMA mapping core to allocate
         * VAs. This will allocate a corresponding IOMMU domain.
         *
         * TODO:
         * - Create one mapping per context (TLB).
         * - Make the mapping size configurable ? We currently use a 2GB mapping
         *   at a 1GB offset to ensure that NULL VAs will fault.
         */
        mmu = to_priv(dev)->mmu;
        if (!mmu->mapping) {
                struct dma_iommu_mapping *mapping;

                mapping = arm_iommu_create_mapping(&platform_bus_type,
                                                   SZ_1G, SZ_2G);
                if (IS_ERR(mapping)) {
                        dev_err(mmu->dev, "failed to create ARM IOMMU mapping\n");
                        ret = PTR_ERR(mapping);
                        goto error;
                }

                mmu->mapping = mapping;
        }

        /* Attach the ARM VA mapping to the device. */
        ret = arm_iommu_attach_device(dev, mmu->mapping);
        if (ret < 0) {
                dev_err(dev, "Failed to attach device to VA mapping\n");
                goto error;
        }

        return 0;

error:
        if (mmu)
                arm_iommu_release_mapping(mmu->mapping);

        if (!IS_ERR_OR_NULL(group))
                iommu_group_remove_device(dev);

        kfree(to_priv(dev)->utlbs);
        kfree(to_priv(dev));
        set_priv(dev, NULL);

        return ret;
}

static void ipmmu_remove_device(struct device *dev)
{
        struct ipmmu_vmsa_iommu_priv *priv = to_priv(dev);

        arm_iommu_detach_device(dev);
        iommu_group_remove_device(dev);

        kfree(priv->utlbs);
        kfree(priv);

        set_priv(dev, NULL);
}

static const struct iommu_ops ipmmu_ops = {
        .domain_alloc = ipmmu_domain_alloc,
        .domain_free = ipmmu_domain_free,
        .attach_dev = ipmmu_attach_device,
        .detach_dev = ipmmu_detach_device,
        .map = ipmmu_map,
        .unmap = ipmmu_unmap,
        .map_sg = default_iommu_map_sg,
        .iova_to_phys = ipmmu_iova_to_phys,
        .add_device = ipmmu_add_device,
        .remove_device = ipmmu_remove_device,
        .pgsize_bitmap = SZ_1G | SZ_2M | SZ_4K,
};

#endif /* !CONFIG_ARM && CONFIG_IOMMU_DMA */

#ifdef CONFIG_IOMMU_DMA

static DEFINE_SPINLOCK(ipmmu_slave_devices_lock);
static LIST_HEAD(ipmmu_slave_devices);

static struct iommu_domain *ipmmu_domain_alloc_dma(unsigned type)
{
        struct iommu_domain *io_domain = NULL;

        switch (type) {
        case IOMMU_DOMAIN_UNMANAGED:
                io_domain = __ipmmu_domain_alloc(type);
                break;

        case IOMMU_DOMAIN_DMA:
                io_domain = __ipmmu_domain_alloc(type);
                if (io_domain)
                        iommu_get_dma_cookie(io_domain);
                break;
        }

        return io_domain;
}

static void ipmmu_domain_free_dma(struct iommu_domain *io_domain)
{
        switch (io_domain->type) {
        case IOMMU_DOMAIN_DMA:
                iommu_put_dma_cookie(io_domain);
                /* fall-through */
        default:
                ipmmu_domain_free(io_domain);
                break;
        }
}

static int ipmmu_add_device_dma(struct device *dev)
{
        struct iommu_fwspec *fwspec = dev->iommu_fwspec;
        struct iommu_group *group;

        /*
         * Only let through devices that have been verified in xlate()
         * We may get called with dev->iommu_fwspec set to NULL.
         */
        if (!fwspec || !fwspec->iommu_priv)
                return -ENODEV;

        group = iommu_group_get_for_dev(dev);
        if (IS_ERR(group))
                return PTR_ERR(group);

        spin_lock(&ipmmu_slave_devices_lock);
        list_add(&to_priv(dev)->list, &ipmmu_slave_devices);
        spin_unlock(&ipmmu_slave_devices_lock);
        return 0;
}

static void ipmmu_remove_device_dma(struct device *dev)
{
        struct ipmmu_vmsa_iommu_priv *priv = to_priv(dev);

        spin_lock(&ipmmu_slave_devices_lock);
        list_del(&priv->list);
        spin_unlock(&ipmmu_slave_devices_lock);

        iommu_group_remove_device(dev);
}

static struct device *ipmmu_find_sibling_device(struct device *dev)
{
        struct ipmmu_vmsa_iommu_priv *priv = to_priv(dev);
        struct ipmmu_vmsa_iommu_priv *sibling_priv = NULL;
        bool found = false;

        spin_lock(&ipmmu_slave_devices_lock);

        list_for_each_entry(sibling_priv, &ipmmu_slave_devices, list) {
                if (priv == sibling_priv)
                        continue;
                if (sibling_priv->mmu == priv->mmu) {
                        found = true;
                        break;
                }
        }

        spin_unlock(&ipmmu_slave_devices_lock);

        return found ? sibling_priv->dev : NULL;
}

static struct iommu_group *ipmmu_find_group_dma(struct device *dev)
{
        struct iommu_group *group;
        struct device *sibling;

        sibling = ipmmu_find_sibling_device(dev);
        if (sibling)
                group = iommu_group_get(sibling);
        if (!sibling || IS_ERR(group))
                group = generic_device_group(dev);

        return group;
}

static int ipmmu_of_xlate_dma(struct device *dev,
                              struct of_phandle_args *spec)
{
        /* If the IPMMU device is disabled in DT then return error
         * to make sure the of_iommu code does not install ops
         * even though the iommu device is disabled
         */
        if (!of_device_is_available(spec->np))
                return -ENODEV;

        return ipmmu_init_platform_device(dev);
}

static const struct iommu_ops ipmmu_ops = {
        .domain_alloc = ipmmu_domain_alloc_dma,
        .domain_free = ipmmu_domain_free_dma,
        .attach_dev = ipmmu_attach_device,
        .detach_dev = ipmmu_detach_device,
        .map = ipmmu_map,
        .unmap = ipmmu_unmap,
        .map_sg = default_iommu_map_sg,
        .iova_to_phys = ipmmu_iova_to_phys,
        .add_device = ipmmu_add_device_dma,
        .remove_device = ipmmu_remove_device_dma,
        .device_group = ipmmu_find_group_dma,
        .pgsize_bitmap = SZ_1G | SZ_2M | SZ_4K,
        .of_xlate = ipmmu_of_xlate_dma,
};

#endif /* CONFIG_IOMMU_DMA */

/* -----------------------------------------------------------------------------
 * Probe/remove and init
 */

static void ipmmu_device_reset(struct ipmmu_vmsa_device *mmu)
{
        unsigned int i;

        /* Disable all contexts. */
        for (i = 0; i < 4; ++i)
                ipmmu_write(mmu, i * IM_CTX_SIZE + IMCTR, 0);
}

static int ipmmu_probe(struct platform_device *pdev)
{
        struct ipmmu_vmsa_device *mmu;
        struct resource *res;
        int irq;
        int ret;

        mmu = devm_kzalloc(&pdev->dev, sizeof(*mmu), GFP_KERNEL);
        if (!mmu) {
                dev_err(&pdev->dev, "cannot allocate device data\n");
                return -ENOMEM;
        }

        mmu->dev = &pdev->dev;
        mmu->num_utlbs = 32;
        spin_lock_init(&mmu->lock);
        bitmap_zero(mmu->ctx, IPMMU_CTX_MAX);

        /* Map I/O memory and request IRQ. */
        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        mmu->base = devm_ioremap_resource(&pdev->dev, res);
        if (IS_ERR(mmu->base))
                return PTR_ERR(mmu->base);

        /*
         * The IPMMU has two register banks, for secure and non-secure modes.
         * The bank mapped at the beginning of the IPMMU address space
         * corresponds to the running mode of the CPU. When running in secure
         * mode the non-secure register bank is also available at an offset.
         *
         * Secure mode operation isn't clearly documented and is thus currently
         * not implemented in the driver. Furthermore, preliminary tests of
         * non-secure operation with the main register bank were not successful.
         * Offset the registers base unconditionally to point to the non-secure
         * alias space for now.
         */
        mmu->base += IM_NS_ALIAS_OFFSET;

        irq = platform_get_irq(pdev, 0);
        if (irq < 0) {
                dev_err(&pdev->dev, "no IRQ found\n");
                return irq;
        }

        ret = devm_request_irq(&pdev->dev, irq, ipmmu_irq, 0,
                               dev_name(&pdev->dev), mmu);
        if (ret < 0) {
                dev_err(&pdev->dev, "failed to request IRQ %d\n", irq);
                return ret;
        }

        ipmmu_device_reset(mmu);

        /*
         * We can't create the ARM mapping here as it requires the bus to have
         * an IOMMU, which only happens when bus_set_iommu() is called in
         * ipmmu_init() after the probe function returns.
         */

        spin_lock(&ipmmu_devices_lock);
        list_add(&mmu->list, &ipmmu_devices);
        spin_unlock(&ipmmu_devices_lock);

        platform_set_drvdata(pdev, mmu);

        return 0;
}

static int ipmmu_remove(struct platform_device *pdev)
{
        struct ipmmu_vmsa_device *mmu = platform_get_drvdata(pdev);

        spin_lock(&ipmmu_devices_lock);
        list_del(&mmu->list);
        spin_unlock(&ipmmu_devices_lock);

#if defined(CONFIG_ARM) && !defined(CONFIG_IOMMU_DMA)
        arm_iommu_release_mapping(mmu->mapping);
#endif

        ipmmu_device_reset(mmu);

        return 0;
}

static const struct of_device_id ipmmu_of_ids[] = {
        { .compatible = "renesas,ipmmu-vmsa", },
        { }
};

static struct platform_driver ipmmu_driver = {
        .driver = {
                .name = "ipmmu-vmsa",
                .of_match_table = of_match_ptr(ipmmu_of_ids),
        },
        .probe = ipmmu_probe,
        .remove = ipmmu_remove,
};

static int __init ipmmu_init(void)
{
        int ret;

        ret = platform_driver_register(&ipmmu_driver);
        if (ret < 0)
                return ret;

        if (!iommu_present(&platform_bus_type))
                bus_set_iommu(&platform_bus_type, &ipmmu_ops);

        return 0;
}

static void __exit ipmmu_exit(void)
{
        return platform_driver_unregister(&ipmmu_driver);
}

subsys_initcall(ipmmu_init);
module_exit(ipmmu_exit);

MODULE_DESCRIPTION("IOMMU API for Renesas VMSA-compatible IPMMU");
MODULE_AUTHOR("Laurent Pinchart <laurent.pinchart@ideasonboard.com>");
MODULE_LICENSE("GPL v2");