// SPDX-License-Identifier:     GPL-2.0
/* Copyright 2019 Linaro, Ltd, Rob Herring <robh@kernel.org> */
#include <linux/atomic.h>
#include <linux/bitfield.h>
#include <linux/delay.h>
#include <linux/dma-mapping.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/iopoll.h>
#include <linux/io-pgtable.h>
#include <linux/iommu.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
#include <linux/shmem_fs.h>
#include <linux/sizes.h>

#include "panfrost_device.h"
#include "panfrost_mmu.h"
#include "panfrost_gem.h"
#include "panfrost_features.h"
#include "panfrost_regs.h"

#define mmu_write(dev, reg, data) writel(data, dev->iomem + reg)
#define mmu_read(dev, reg) readl(dev->iomem + reg)

static int wait_ready(struct panfrost_device *pfdev, u32 as_nr)
{
        int ret;
        u32 val;

        /* Wait for the MMU status to indicate there is no active command, in
         * case one is pending. */
        ret = readl_relaxed_poll_timeout_atomic(pfdev->iomem + AS_STATUS(as_nr),
                val, !(val & AS_STATUS_AS_ACTIVE), 10, 1000);

        if (ret)
                dev_err(pfdev->dev, "AS_ACTIVE bit stuck\n");

        return ret;
}

static int write_cmd(struct panfrost_device *pfdev, u32 as_nr, u32 cmd)
{
        int status;

        /* write AS_COMMAND when MMU is ready to accept another command */
        status = wait_ready(pfdev, as_nr);
        if (!status)
                mmu_write(pfdev, AS_COMMAND(as_nr), cmd);

        return status;
}

static void lock_region(struct panfrost_device *pfdev, u32 as_nr,
                        u64 iova, size_t size)
{
        u8 region_width;
        u64 region = iova & PAGE_MASK;
        /*
         * fls returns:
         * 1 .. 32
         *
         * 10 + fls(num_pages)
         * results in the range (11 .. 42)
         */

        size = round_up(size, PAGE_SIZE);

        region_width = 10 + fls(size >> PAGE_SHIFT);
        if ((size >> PAGE_SHIFT) != (1ul << (region_width - 11))) {
                /* not pow2, so must go up to the next pow2 */
                region_width += 1;
        }
        region |= region_width;

        /* Lock the region that needs to be updated */
        mmu_write(pfdev, AS_LOCKADDR_LO(as_nr), region & 0xFFFFFFFFUL);
        mmu_write(pfdev, AS_LOCKADDR_HI(as_nr), (region >> 32) & 0xFFFFFFFFUL);
        write_cmd(pfdev, as_nr, AS_COMMAND_LOCK);
}


static int mmu_hw_do_operation_locked(struct panfrost_device *pfdev, int as_nr,
                                      u64 iova, size_t size, u32 op)
{
        if (as_nr < 0)
                return 0;

        if (op != AS_COMMAND_UNLOCK)
                lock_region(pfdev, as_nr, iova, size);

        /* Run the MMU operation */
        write_cmd(pfdev, as_nr, op);

        /* Wait for the flush to complete */
        return wait_ready(pfdev, as_nr);
}

static int mmu_hw_do_operation(struct panfrost_device *pfdev,
                               struct panfrost_mmu *mmu,
                               u64 iova, size_t size, u32 op)
{
        int ret;

        spin_lock(&pfdev->as_lock);
        ret = mmu_hw_do_operation_locked(pfdev, mmu->as, iova, size, op);
        spin_unlock(&pfdev->as_lock);
        return ret;
}

static void panfrost_mmu_enable(struct panfrost_device *pfdev, struct panfrost_mmu *mmu)
{
        int as_nr = mmu->as;
        struct io_pgtable_cfg *cfg = &mmu->pgtbl_cfg;
        u64 transtab = cfg->arm_mali_lpae_cfg.transtab;
        u64 memattr = cfg->arm_mali_lpae_cfg.memattr;

        mmu_hw_do_operation_locked(pfdev, as_nr, 0, ~0UL, AS_COMMAND_FLUSH_MEM);

        mmu_write(pfdev, AS_TRANSTAB_LO(as_nr), transtab & 0xffffffffUL);
        mmu_write(pfdev, AS_TRANSTAB_HI(as_nr), transtab >> 32);

        /* Need to revisit mem attrs.
         * NC is the default, Mali driver is inner WT.
         */
        mmu_write(pfdev, AS_MEMATTR_LO(as_nr), memattr & 0xffffffffUL);
        mmu_write(pfdev, AS_MEMATTR_HI(as_nr), memattr >> 32);

        write_cmd(pfdev, as_nr, AS_COMMAND_UPDATE);
}

static void panfrost_mmu_disable(struct panfrost_device *pfdev, u32 as_nr)
{
        mmu_hw_do_operation_locked(pfdev, as_nr, 0, ~0UL, AS_COMMAND_FLUSH_MEM);

        mmu_write(pfdev, AS_TRANSTAB_LO(as_nr), 0);
        mmu_write(pfdev, AS_TRANSTAB_HI(as_nr), 0);

        mmu_write(pfdev, AS_MEMATTR_LO(as_nr), 0);
        mmu_write(pfdev, AS_MEMATTR_HI(as_nr), 0);

        write_cmd(pfdev, as_nr, AS_COMMAND_UPDATE);
}

u32 panfrost_mmu_as_get(struct panfrost_device *pfdev, struct panfrost_mmu *mmu)
{
        int as;

        spin_lock(&pfdev->as_lock);

        as = mmu->as;
        if (as >= 0) {
                int en = atomic_inc_return(&mmu->as_count);

                /*
                 * AS can be retained by active jobs or a perfcnt context,
                 * hence the '+ 1' here.
                 */
                WARN_ON(en >= (NUM_JOB_SLOTS + 1));

                list_move(&mmu->list, &pfdev->as_lru_list);
                goto out;
        }

        /* Check for a free AS */
        as = ffz(pfdev->as_alloc_mask);
        if (!(BIT(as) & pfdev->features.as_present)) {
                struct panfrost_mmu *lru_mmu;

                list_for_each_entry_reverse(lru_mmu, &pfdev->as_lru_list, list) {
                        if (!atomic_read(&lru_mmu->as_count))
                                break;
                }
                WARN_ON(&lru_mmu->list == &pfdev->as_lru_list);

                list_del_init(&lru_mmu->list);
                as = lru_mmu->as;

                WARN_ON(as < 0);
                lru_mmu->as = -1;
        }

        /* Assign the free or reclaimed AS to the FD */
        mmu->as = as;
        set_bit(as, &pfdev->as_alloc_mask);
        atomic_set(&mmu->as_count, 1);
        list_add(&mmu->list, &pfdev->as_lru_list);

        dev_dbg(pfdev->dev, "Assigned AS%d to mmu %p, alloc_mask=%lx", as, mmu, pfdev->as_alloc_mask);

        panfrost_mmu_enable(pfdev, mmu);

out:
        spin_unlock(&pfdev->as_lock);
        return as;
}

void panfrost_mmu_as_put(struct panfrost_device *pfdev, struct panfrost_mmu *mmu)
{
        atomic_dec(&mmu->as_count);
        WARN_ON(atomic_read(&mmu->as_count) < 0);
}

void panfrost_mmu_reset(struct panfrost_device *pfdev)
{
        struct panfrost_mmu *mmu, *mmu_tmp;

        spin_lock(&pfdev->as_lock);

        pfdev->as_alloc_mask = 0;

        list_for_each_entry_safe(mmu, mmu_tmp, &pfdev->as_lru_list, list) {
                mmu->as = -1;
                atomic_set(&mmu->as_count, 0);
                list_del_init(&mmu->list);
        }

        spin_unlock(&pfdev->as_lock);

        mmu_write(pfdev, MMU_INT_CLEAR, ~0);
        mmu_write(pfdev, MMU_INT_MASK, ~0);
}

static size_t get_pgsize(u64 addr, size_t size)
{
        if (addr & (SZ_2M - 1) || size < SZ_2M)
                return SZ_4K;

        return SZ_2M;
}

static void panfrost_mmu_flush_range(struct panfrost_device *pfdev,
                                     struct panfrost_mmu *mmu,
                                     u64 iova, size_t size)
{
        if (mmu->as < 0)
                return;

        pm_runtime_get_noresume(pfdev->dev);

        /* Flush the PTs only if we're already awake */
        if (pm_runtime_active(pfdev->dev))
                mmu_hw_do_operation(pfdev, mmu, iova, size, AS_COMMAND_FLUSH_PT);

        pm_runtime_put_sync_autosuspend(pfdev->dev);
}

static int mmu_map_sg(struct panfrost_device *pfdev, struct panfrost_mmu *mmu,
                      u64 iova, int prot, struct sg_table *sgt)
{
        unsigned int count;
        struct scatterlist *sgl;
        struct io_pgtable_ops *ops = mmu->pgtbl_ops;
        u64 start_iova = iova;

        for_each_sg(sgt->sgl, sgl, sgt->nents, count) {
                unsigned long paddr = sg_dma_address(sgl);
                size_t len = sg_dma_len(sgl);

                dev_dbg(pfdev->dev, "map: as=%d, iova=%llx, paddr=%lx, len=%zx", mmu->as, iova, paddr, len);

                while (len) {
                        size_t pgsize = get_pgsize(iova | paddr, len);

                        ops->map(ops, iova, paddr, pgsize, prot, GFP_KERNEL);
                        iova += pgsize;
                        paddr += pgsize;
                        len -= pgsize;
                }
        }

        panfrost_mmu_flush_range(pfdev, mmu, start_iova, iova - start_iova);

        return 0;
}

int panfrost_mmu_map(struct panfrost_gem_mapping *mapping)
{
        struct panfrost_gem_object *bo = mapping->obj;
        struct drm_gem_object *obj = &bo->base.base;
        struct panfrost_device *pfdev = to_panfrost_device(obj->dev);
        struct sg_table *sgt;
        int prot = IOMMU_READ | IOMMU_WRITE;

        if (WARN_ON(mapping->active))
                return 0;

        if (bo->noexec)
                prot |= IOMMU_NOEXEC;

        sgt = drm_gem_shmem_get_pages_sgt(obj);
        if (WARN_ON(IS_ERR(sgt)))
                return PTR_ERR(sgt);

        mmu_map_sg(pfdev, mapping->mmu, mapping->mmnode.start << PAGE_SHIFT,
                   prot, sgt);
        mapping->active = true;

        return 0;
}

void panfrost_mmu_unmap(struct panfrost_gem_mapping *mapping)
{
        struct panfrost_gem_object *bo = mapping->obj;
        struct drm_gem_object *obj = &bo->base.base;
        struct panfrost_device *pfdev = to_panfrost_device(obj->dev);
        struct io_pgtable_ops *ops = mapping->mmu->pgtbl_ops;
        u64 iova = mapping->mmnode.start << PAGE_SHIFT;
        size_t len = mapping->mmnode.size << PAGE_SHIFT;
        size_t unmapped_len = 0;

        if (WARN_ON(!mapping->active))
                return;

        dev_dbg(pfdev->dev, "unmap: as=%d, iova=%llx, len=%zx",
                mapping->mmu->as, iova, len);

        while (unmapped_len < len) {
                size_t unmapped_page;
                size_t pgsize = get_pgsize(iova, len - unmapped_len);

                if (ops->iova_to_phys(ops, iova)) {
                        unmapped_page = ops->unmap(ops, iova, pgsize, NULL);
                        WARN_ON(unmapped_page != pgsize);
                }
                iova += pgsize;
                unmapped_len += pgsize;
        }

        panfrost_mmu_flush_range(pfdev, mapping->mmu,
                                 mapping->mmnode.start << PAGE_SHIFT, len);
        mapping->active = false;
}

static void mmu_tlb_inv_context_s1(void *cookie)
{}

static void mmu_tlb_sync_context(void *cookie)
{
        //struct panfrost_device *pfdev = cookie;
        // TODO: Wait 1000 GPU cycles for HW_ISSUE_6367/T60X
}

static void mmu_tlb_flush_walk(unsigned long iova, size_t size, size_t granule,
                               void *cookie)
{
        mmu_tlb_sync_context(cookie);
}

static void mmu_tlb_flush_leaf(unsigned long iova, size_t size, size_t granule,
                               void *cookie)
{
        mmu_tlb_sync_context(cookie);
}

static const struct iommu_flush_ops mmu_tlb_ops = {
        .tlb_flush_all  = mmu_tlb_inv_context_s1,
        .tlb_flush_walk = mmu_tlb_flush_walk,
        .tlb_flush_leaf = mmu_tlb_flush_leaf,
};

int panfrost_mmu_pgtable_alloc(struct panfrost_file_priv *priv)
{
        struct panfrost_mmu *mmu = &priv->mmu;
        struct panfrost_device *pfdev = priv->pfdev;

        INIT_LIST_HEAD(&mmu->list);
        mmu->as = -1;

        mmu->pgtbl_cfg = (struct io_pgtable_cfg) {
                .pgsize_bitmap  = SZ_4K | SZ_2M,
                .ias            = FIELD_GET(0xff, pfdev->features.mmu_features),
                .oas            = FIELD_GET(0xff00, pfdev->features.mmu_features),
                .tlb            = &mmu_tlb_ops,
                .iommu_dev      = pfdev->dev,
        };

        mmu->pgtbl_ops = alloc_io_pgtable_ops(ARM_MALI_LPAE, &mmu->pgtbl_cfg,
                                              priv);
        if (!mmu->pgtbl_ops)
                return -EINVAL;

        return 0;
}

void panfrost_mmu_pgtable_free(struct panfrost_file_priv *priv)
{
        struct panfrost_device *pfdev = priv->pfdev;
        struct panfrost_mmu *mmu = &priv->mmu;

        spin_lock(&pfdev->as_lock);
        if (mmu->as >= 0) {
                pm_runtime_get_noresume(pfdev->dev);
                if (pm_runtime_active(pfdev->dev))
                        panfrost_mmu_disable(pfdev, mmu->as);
                pm_runtime_put_autosuspend(pfdev->dev);

                clear_bit(mmu->as, &pfdev->as_alloc_mask);
                clear_bit(mmu->as, &pfdev->as_in_use_mask);
                list_del(&mmu->list);
        }
        spin_unlock(&pfdev->as_lock);

        free_io_pgtable_ops(mmu->pgtbl_ops);
}

static struct panfrost_gem_mapping *
addr_to_mapping(struct panfrost_device *pfdev, int as, u64 addr)
{
        struct panfrost_gem_mapping *mapping = NULL;
        struct panfrost_file_priv *priv;
        struct drm_mm_node *node;
        u64 offset = addr >> PAGE_SHIFT;
        struct panfrost_mmu *mmu;

        spin_lock(&pfdev->as_lock);
        list_for_each_entry(mmu, &pfdev->as_lru_list, list) {
                if (as == mmu->as)
                        goto found_mmu;
        }
        goto out;

found_mmu:
        priv = container_of(mmu, struct panfrost_file_priv, mmu);

        spin_lock(&priv->mm_lock);

        drm_mm_for_each_node(node, &priv->mm) {
                if (offset >= node->start &&
                    offset < (node->start + node->size)) {
                        mapping = drm_mm_node_to_panfrost_mapping(node);

                        kref_get(&mapping->refcount);
                        break;
                }
        }

        spin_unlock(&priv->mm_lock);
out:
        spin_unlock(&pfdev->as_lock);
        return mapping;
}

#define NUM_FAULT_PAGES (SZ_2M / PAGE_SIZE)

static int panfrost_mmu_map_fault_addr(struct panfrost_device *pfdev, int as,
                                       u64 addr)
{
        int ret, i;
        struct panfrost_gem_mapping *bomapping;
        struct panfrost_gem_object *bo;
        struct address_space *mapping;
        pgoff_t page_offset;
        struct sg_table *sgt;
        struct page **pages;

        bomapping = addr_to_mapping(pfdev, as, addr);
        if (!bomapping)
                return -ENOENT;

        bo = bomapping->obj;
        if (!bo->is_heap) {
                dev_WARN(pfdev->dev, "matching BO is not heap type (GPU VA = %llx)",
                         bomapping->mmnode.start << PAGE_SHIFT);
                ret = -EINVAL;
                goto err_bo;
        }
        WARN_ON(bomapping->mmu->as != as);

        /* Assume 2MB alignment and size multiple */
        addr &= ~((u64)SZ_2M - 1);
        page_offset = addr >> PAGE_SHIFT;
        page_offset -= bomapping->mmnode.start;

        mutex_lock(&bo->base.pages_lock);

        if (!bo->base.pages) {
                bo->sgts = kvmalloc_array(bo->base.base.size / SZ_2M,
                                     sizeof(struct sg_table), GFP_KERNEL | __GFP_ZERO);
                if (!bo->sgts) {
                        mutex_unlock(&bo->base.pages_lock);
                        ret = -ENOMEM;
                        goto err_bo;
                }

                pages = kvmalloc_array(bo->base.base.size >> PAGE_SHIFT,
                                       sizeof(struct page *), GFP_KERNEL | __GFP_ZERO);
                if (!pages) {
                        kvfree(bo->sgts);
                        bo->sgts = NULL;
                        mutex_unlock(&bo->base.pages_lock);
                        ret = -ENOMEM;
                        goto err_bo;
                }
                bo->base.pages = pages;
                bo->base.pages_use_count = 1;
        } else
                pages = bo->base.pages;

        mapping = bo->base.base.filp->f_mapping;
        mapping_set_unevictable(mapping);

        for (i = page_offset; i < page_offset + NUM_FAULT_PAGES; i++) {
                pages[i] = shmem_read_mapping_page(mapping, i);
                if (IS_ERR(pages[i])) {
                        mutex_unlock(&bo->base.pages_lock);
                        ret = PTR_ERR(pages[i]);
                        goto err_pages;
                }
        }

        mutex_unlock(&bo->base.pages_lock);

        sgt = &bo->sgts[page_offset / (SZ_2M / PAGE_SIZE)];
        ret = sg_alloc_table_from_pages(sgt, pages + page_offset,
                                        NUM_FAULT_PAGES, 0, SZ_2M, GFP_KERNEL);
        if (ret)
                goto err_pages;

        if (!dma_map_sg(pfdev->dev, sgt->sgl, sgt->nents, DMA_BIDIRECTIONAL)) {
                ret = -EINVAL;
                goto err_map;
        }

        mmu_map_sg(pfdev, bomapping->mmu, addr,
                   IOMMU_WRITE | IOMMU_READ | IOMMU_NOEXEC, sgt);

        bomapping->active = true;

        dev_dbg(pfdev->dev, "mapped page fault @ AS%d %llx", as, addr);

        panfrost_gem_mapping_put(bomapping);

        return 0;

err_map:
        sg_free_table(sgt);
err_pages:
        drm_gem_shmem_put_pages(&bo->base);
err_bo:
        drm_gem_object_put(&bo->base.base);
        return ret;
}

static const char *access_type_name(struct panfrost_device *pfdev,
                u32 fault_status)
{
        switch (fault_status & AS_FAULTSTATUS_ACCESS_TYPE_MASK) {
        case AS_FAULTSTATUS_ACCESS_TYPE_ATOMIC:
                if (panfrost_has_hw_feature(pfdev, HW_FEATURE_AARCH64_MMU))
                        return "ATOMIC";
                else
                        return "UNKNOWN";
        case AS_FAULTSTATUS_ACCESS_TYPE_READ:
                return "READ";
        case AS_FAULTSTATUS_ACCESS_TYPE_WRITE:
                return "WRITE";
        case AS_FAULTSTATUS_ACCESS_TYPE_EX:
                return "EXECUTE";
        default:
                WARN_ON(1);
                return NULL;
        }
}

static irqreturn_t panfrost_mmu_irq_handler(int irq, void *data)
{
        struct panfrost_device *pfdev = data;

        if (!mmu_read(pfdev, MMU_INT_STAT))
                return IRQ_NONE;

        mmu_write(pfdev, MMU_INT_MASK, 0);
        return IRQ_WAKE_THREAD;
}

static irqreturn_t panfrost_mmu_irq_handler_thread(int irq, void *data)
{
        struct panfrost_device *pfdev = data;
        u32 status = mmu_read(pfdev, MMU_INT_RAWSTAT);
        int i, ret;

        for (i = 0; status; i++) {
                u32 mask = BIT(i) | BIT(i + 16);
                u64 addr;
                u32 fault_status;
                u32 exception_type;
                u32 access_type;
                u32 source_id;

                if (!(status & mask))
                        continue;

                fault_status = mmu_read(pfdev, AS_FAULTSTATUS(i));
                addr = mmu_read(pfdev, AS_FAULTADDRESS_LO(i));
                addr |= (u64)mmu_read(pfdev, AS_FAULTADDRESS_HI(i)) << 32;

                /* decode the fault status */
                exception_type = fault_status & 0xFF;
                access_type = (fault_status >> 8) & 0x3;
                source_id = (fault_status >> 16);

                /* Page fault only */
                ret = -1;
                if ((status & mask) == BIT(i) && (exception_type & 0xF8) == 0xC0)
                        ret = panfrost_mmu_map_fault_addr(pfdev, i, addr);

                if (ret)
                        /* terminal fault, print info about the fault */
                        dev_err(pfdev->dev,
                                "Unhandled Page fault in AS%d at VA 0x%016llX\n"
                                "Reason: %s\n"
                                "raw fault status: 0x%X\n"
                                "decoded fault status: %s\n"
                                "exception type 0x%X: %s\n"
                                "access type 0x%X: %s\n"
                                "source id 0x%X\n",
                                i, addr,
                                "TODO",
                                fault_status,
                                (fault_status & (1 << 10) ? "DECODER FAULT" : "SLAVE FAULT"),
                                exception_type, panfrost_exception_name(pfdev, exception_type),
                                access_type, access_type_name(pfdev, fault_status),
                                source_id);

                mmu_write(pfdev, MMU_INT_CLEAR, mask);

                status &= ~mask;
        }

        mmu_write(pfdev, MMU_INT_MASK, ~0);
        return IRQ_HANDLED;
};

int panfrost_mmu_init(struct panfrost_device *pfdev)
{
        int err, irq;

        irq = platform_get_irq_byname(to_platform_device(pfdev->dev), "mmu");
        if (irq <= 0)
                return -ENODEV;

        err = devm_request_threaded_irq(pfdev->dev, irq,
                                        panfrost_mmu_irq_handler,
                                        panfrost_mmu_irq_handler_thread,
                                        IRQF_SHARED, KBUILD_MODNAME "-mmu",
                                        pfdev);

        if (err) {
                dev_err(pfdev->dev, "failed to request mmu irq");
                return err;
        }

        return 0;
}

void panfrost_mmu_fini(struct panfrost_device *pfdev)
{
        mmu_write(pfdev, MMU_INT_MASK, 0);
}