// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2018 Intel Corporation.
 * Copyright 2018 Google LLC.
 *
 * Author: Tuukka Toivonen <tuukka.toivonen@intel.com>
 * Author: Sakari Ailus <sakari.ailus@linux.intel.com>
 * Author: Samu Onkalo <samu.onkalo@intel.com>
 * Author: Tomasz Figa <tfiga@chromium.org>
 *
 */

#include <linux/dma-mapping.h>
#include <linux/iopoll.h>
#include <linux/pm_runtime.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>

#include <asm/set_memory.h>

#include "ipu3-mmu.h"

#define IPU3_PT_BITS            10
#define IPU3_PT_PTES            (1UL << IPU3_PT_BITS)
#define IPU3_PT_SIZE            (IPU3_PT_PTES << 2)
#define IPU3_PT_ORDER           (IPU3_PT_SIZE >> PAGE_SHIFT)

#define IPU3_ADDR2PTE(addr)     ((addr) >> IPU3_PAGE_SHIFT)
#define IPU3_PTE2ADDR(pte)      ((phys_addr_t)(pte) << IPU3_PAGE_SHIFT)

#define IPU3_L2PT_SHIFT         IPU3_PT_BITS
#define IPU3_L2PT_MASK          ((1UL << IPU3_L2PT_SHIFT) - 1)

#define IPU3_L1PT_SHIFT         IPU3_PT_BITS
#define IPU3_L1PT_MASK          ((1UL << IPU3_L1PT_SHIFT) - 1)

#define IPU3_MMU_ADDRESS_BITS   (IPU3_PAGE_SHIFT + \
                                 IPU3_L2PT_SHIFT + \
                                 IPU3_L1PT_SHIFT)

#define IMGU_REG_BASE           0x4000
#define REG_TLB_INVALIDATE      (IMGU_REG_BASE + 0x300)
#define TLB_INVALIDATE          1
#define REG_L1_PHYS             (IMGU_REG_BASE + 0x304) /* 27-bit pfn */
#define REG_GP_HALT             (IMGU_REG_BASE + 0x5dc)
#define REG_GP_HALTED           (IMGU_REG_BASE + 0x5e0)

struct imgu_mmu {
        struct device *dev;
        void __iomem *base;
        /* protect access to l2pts, l1pt */
        spinlock_t lock;

        void *dummy_page;
        u32 dummy_page_pteval;

        u32 *dummy_l2pt;
        u32 dummy_l2pt_pteval;

        u32 **l2pts;
        u32 *l1pt;

        struct imgu_mmu_info geometry;
};

static inline struct imgu_mmu *to_imgu_mmu(struct imgu_mmu_info *info)
{
        return container_of(info, struct imgu_mmu, geometry);
}

/**
 * imgu_mmu_tlb_invalidate - invalidate translation look-aside buffer
 * @mmu: MMU to perform the invalidate operation on
 *
 * This function invalidates the whole TLB. Must be called when the hardware
 * is powered on.
 */
static void imgu_mmu_tlb_invalidate(struct imgu_mmu *mmu)
{
        writel(TLB_INVALIDATE, mmu->base + REG_TLB_INVALIDATE);
}

static void call_if_imgu_is_powered(struct imgu_mmu *mmu,
                                    void (*func)(struct imgu_mmu *mmu))
{
        if (!pm_runtime_get_if_in_use(mmu->dev))
                return;

        func(mmu);
        pm_runtime_put(mmu->dev);
}

/**
 * imgu_mmu_set_halt - set CIO gate halt bit
 * @mmu: MMU to set the CIO gate bit in.
 * @halt: Desired state of the gate bit.
 *
 * This function sets the CIO gate bit that controls whether external memory
 * accesses are allowed. Must be called when the hardware is powered on.
 */
static void imgu_mmu_set_halt(struct imgu_mmu *mmu, bool halt)
{
        int ret;
        u32 val;

        writel(halt, mmu->base + REG_GP_HALT);
        ret = readl_poll_timeout(mmu->base + REG_GP_HALTED,
                                 val, (val & 1) == halt, 1000, 100000);

        if (ret)
                dev_err(mmu->dev, "failed to %s CIO gate halt\n",
                        halt ? "set" : "clear");
}

/**
 * imgu_mmu_alloc_page_table - allocate a pre-filled page table
 * @pteval: Value to initialize for page table entries with.
 *
 * Return: Pointer to allocated page table or NULL on failure.
 */
static u32 *imgu_mmu_alloc_page_table(u32 pteval)
{
        u32 *pt;
        int pte;

        pt = (u32 *)__get_free_page(GFP_KERNEL);
        if (!pt)
                return NULL;

        for (pte = 0; pte < IPU3_PT_PTES; pte++)
                pt[pte] = pteval;

        set_memory_uc((unsigned long)pt, IPU3_PT_ORDER);

        return pt;
}

/**
 * imgu_mmu_free_page_table - free page table
 * @pt: Page table to free.
 */
static void imgu_mmu_free_page_table(u32 *pt)
{
        set_memory_wb((unsigned long)pt, IPU3_PT_ORDER);
        free_page((unsigned long)pt);
}

/**
 * address_to_pte_idx - split IOVA into L1 and L2 page table indices
 * @iova: IOVA to split.
 * @l1pt_idx: Output for the L1 page table index.
 * @l2pt_idx: Output for the L2 page index.
 */
static inline void address_to_pte_idx(unsigned long iova, u32 *l1pt_idx,
                                      u32 *l2pt_idx)
{
        iova >>= IPU3_PAGE_SHIFT;

        if (l2pt_idx)
                *l2pt_idx = iova & IPU3_L2PT_MASK;

        iova >>= IPU3_L2PT_SHIFT;

        if (l1pt_idx)
                *l1pt_idx = iova & IPU3_L1PT_MASK;
}

static u32 *imgu_mmu_get_l2pt(struct imgu_mmu *mmu, u32 l1pt_idx)
{
        unsigned long flags;
        u32 *l2pt, *new_l2pt;
        u32 pteval;

        spin_lock_irqsave(&mmu->lock, flags);

        l2pt = mmu->l2pts[l1pt_idx];
        if (l2pt) {
                spin_unlock_irqrestore(&mmu->lock, flags);
                return l2pt;
        }

        spin_unlock_irqrestore(&mmu->lock, flags);

        new_l2pt = imgu_mmu_alloc_page_table(mmu->dummy_page_pteval);
        if (!new_l2pt)
                return NULL;

        spin_lock_irqsave(&mmu->lock, flags);

        dev_dbg(mmu->dev, "allocated page table %p for l1pt_idx %u\n",
                new_l2pt, l1pt_idx);

        l2pt = mmu->l2pts[l1pt_idx];
        if (l2pt) {
                spin_unlock_irqrestore(&mmu->lock, flags);
                imgu_mmu_free_page_table(new_l2pt);
                return l2pt;
        }

        l2pt = new_l2pt;
        mmu->l2pts[l1pt_idx] = new_l2pt;

        pteval = IPU3_ADDR2PTE(virt_to_phys(new_l2pt));
        mmu->l1pt[l1pt_idx] = pteval;

        spin_unlock_irqrestore(&mmu->lock, flags);
        return l2pt;
}

static int __imgu_mmu_map(struct imgu_mmu *mmu, unsigned long iova,
                          phys_addr_t paddr)
{
        u32 l1pt_idx, l2pt_idx;
        unsigned long flags;
        u32 *l2pt;

        if (!mmu)
                return -ENODEV;

        address_to_pte_idx(iova, &l1pt_idx, &l2pt_idx);

        l2pt = imgu_mmu_get_l2pt(mmu, l1pt_idx);
        if (!l2pt)
                return -ENOMEM;

        spin_lock_irqsave(&mmu->lock, flags);

        if (l2pt[l2pt_idx] != mmu->dummy_page_pteval) {
                spin_unlock_irqrestore(&mmu->lock, flags);
                return -EBUSY;
        }

        l2pt[l2pt_idx] = IPU3_ADDR2PTE(paddr);

        spin_unlock_irqrestore(&mmu->lock, flags);

        return 0;
}

/**
 * imgu_mmu_map - map a buffer to a physical address
 *
 * @info: MMU mappable range
 * @iova: the virtual address
 * @paddr: the physical address
 * @size: length of the mappable area
 *
 * The function has been adapted from iommu_map() in
 * drivers/iommu/iommu.c .
 */
int imgu_mmu_map(struct imgu_mmu_info *info, unsigned long iova,
                 phys_addr_t paddr, size_t size)
{
        struct imgu_mmu *mmu = to_imgu_mmu(info);
        int ret = 0;

        /*
         * both the virtual address and the physical one, as well as
         * the size of the mapping, must be aligned (at least) to the
         * size of the smallest page supported by the hardware
         */
        if (!IS_ALIGNED(iova | paddr | size, IPU3_PAGE_SIZE)) {
                dev_err(mmu->dev, "unaligned: iova 0x%lx pa %pa size 0x%zx\n",
                        iova, &paddr, size);
                return -EINVAL;
        }

        dev_dbg(mmu->dev, "map: iova 0x%lx pa %pa size 0x%zx\n",
                iova, &paddr, size);

        while (size) {
                dev_dbg(mmu->dev, "mapping: iova 0x%lx pa %pa\n", iova, &paddr);

                ret = __imgu_mmu_map(mmu, iova, paddr);
                if (ret)
                        break;

                iova += IPU3_PAGE_SIZE;
                paddr += IPU3_PAGE_SIZE;
                size -= IPU3_PAGE_SIZE;
        }

        call_if_imgu_is_powered(mmu, imgu_mmu_tlb_invalidate);

        return ret;
}

/**
 * imgu_mmu_map_sg - Map a scatterlist
 *
 * @info: MMU mappable range
 * @iova: the virtual address
 * @sg: the scatterlist to map
 * @nents: number of entries in the scatterlist
 *
 * The function has been adapted from default_iommu_map_sg() in
 * drivers/iommu/iommu.c .
 */
size_t imgu_mmu_map_sg(struct imgu_mmu_info *info, unsigned long iova,
                       struct scatterlist *sg, unsigned int nents)
{
        struct imgu_mmu *mmu = to_imgu_mmu(info);
        struct scatterlist *s;
        size_t s_length, mapped = 0;
        unsigned int i;
        int ret;

        for_each_sg(sg, s, nents, i) {
                phys_addr_t phys = page_to_phys(sg_page(s)) + s->offset;

                s_length = s->length;

                if (!IS_ALIGNED(s->offset, IPU3_PAGE_SIZE))
                        goto out_err;

                /* must be IPU3_PAGE_SIZE aligned to be mapped singlely */
                if (i == nents - 1 && !IS_ALIGNED(s->length, IPU3_PAGE_SIZE))
                        s_length = PAGE_ALIGN(s->length);

                ret = imgu_mmu_map(info, iova + mapped, phys, s_length);
                if (ret)
                        goto out_err;

                mapped += s_length;
        }

        call_if_imgu_is_powered(mmu, imgu_mmu_tlb_invalidate);

        return mapped;

out_err:
        /* undo mappings already done */
        imgu_mmu_unmap(info, iova, mapped);

        return 0;
}

static size_t __imgu_mmu_unmap(struct imgu_mmu *mmu,
                               unsigned long iova, size_t size)
{
        u32 l1pt_idx, l2pt_idx;
        unsigned long flags;
        size_t unmap = size;
        u32 *l2pt;

        if (!mmu)
                return 0;

        address_to_pte_idx(iova, &l1pt_idx, &l2pt_idx);

        spin_lock_irqsave(&mmu->lock, flags);

        l2pt = mmu->l2pts[l1pt_idx];
        if (!l2pt) {
                spin_unlock_irqrestore(&mmu->lock, flags);
                return 0;
        }

        if (l2pt[l2pt_idx] == mmu->dummy_page_pteval)
                unmap = 0;

        l2pt[l2pt_idx] = mmu->dummy_page_pteval;

        spin_unlock_irqrestore(&mmu->lock, flags);

        return unmap;
}

/**
 * imgu_mmu_unmap - Unmap a buffer
 *
 * @info: MMU mappable range
 * @iova: the virtual address
 * @size: the length of the buffer
 *
 * The function has been adapted from iommu_unmap() in
 * drivers/iommu/iommu.c .
 */
size_t imgu_mmu_unmap(struct imgu_mmu_info *info, unsigned long iova,
                      size_t size)
{
        struct imgu_mmu *mmu = to_imgu_mmu(info);
        size_t unmapped_page, unmapped = 0;

        /*
         * The virtual address, as well as the size of the mapping, must be
         * aligned (at least) to the size of the smallest page supported
         * by the hardware
         */
        if (!IS_ALIGNED(iova | size, IPU3_PAGE_SIZE)) {
                dev_err(mmu->dev, "unaligned: iova 0x%lx size 0x%zx\n",
                        iova, size);
                return -EINVAL;
        }

        dev_dbg(mmu->dev, "unmap this: iova 0x%lx size 0x%zx\n", iova, size);

        /*
         * Keep iterating until we either unmap 'size' bytes (or more)
         * or we hit an area that isn't mapped.
         */
        while (unmapped < size) {
                unmapped_page = __imgu_mmu_unmap(mmu, iova, IPU3_PAGE_SIZE);
                if (!unmapped_page)
                        break;

                dev_dbg(mmu->dev, "unmapped: iova 0x%lx size 0x%zx\n",
                        iova, unmapped_page);

                iova += unmapped_page;
                unmapped += unmapped_page;
        }

        call_if_imgu_is_powered(mmu, imgu_mmu_tlb_invalidate);

        return unmapped;
}

/**
 * imgu_mmu_init() - initialize IPU3 MMU block
 *
 * @parent:     struct device parent
 * @base:       IOMEM base of hardware registers.
 *
 * Return: Pointer to IPU3 MMU private data pointer or ERR_PTR() on error.
 */
struct imgu_mmu_info *imgu_mmu_init(struct device *parent, void __iomem *base)
{
        struct imgu_mmu *mmu;
        u32 pteval;

        mmu = kzalloc_obj(*mmu);
        if (!mmu)
                return ERR_PTR(-ENOMEM);

        mmu->dev = parent;
        mmu->base = base;
        spin_lock_init(&mmu->lock);

        /* Disallow external memory access when having no valid page tables. */
        imgu_mmu_set_halt(mmu, true);

        /*
         * The MMU does not have a "valid" bit, so we have to use a dummy
         * page for invalid entries.
         */
        mmu->dummy_page = (void *)__get_free_page(GFP_KERNEL);
        if (!mmu->dummy_page)
                goto fail_group;
        pteval = IPU3_ADDR2PTE(virt_to_phys(mmu->dummy_page));
        mmu->dummy_page_pteval = pteval;

        /*
         * Allocate a dummy L2 page table with all entries pointing to
         * the dummy page.
         */
        mmu->dummy_l2pt = imgu_mmu_alloc_page_table(pteval);
        if (!mmu->dummy_l2pt)
                goto fail_dummy_page;
        pteval = IPU3_ADDR2PTE(virt_to_phys(mmu->dummy_l2pt));
        mmu->dummy_l2pt_pteval = pteval;

        /*
         * Allocate the array of L2PT CPU pointers, initialized to zero,
         * which means the dummy L2PT allocated above.
         */
        mmu->l2pts = vzalloc(IPU3_PT_PTES * sizeof(*mmu->l2pts));
        if (!mmu->l2pts)
                goto fail_l2pt;

        /* Allocate the L1 page table. */
        mmu->l1pt = imgu_mmu_alloc_page_table(mmu->dummy_l2pt_pteval);
        if (!mmu->l1pt)
                goto fail_l2pts;

        pteval = IPU3_ADDR2PTE(virt_to_phys(mmu->l1pt));
        writel(pteval, mmu->base + REG_L1_PHYS);
        imgu_mmu_tlb_invalidate(mmu);
        imgu_mmu_set_halt(mmu, false);

        mmu->geometry.aperture_start = 0;
        mmu->geometry.aperture_end = DMA_BIT_MASK(IPU3_MMU_ADDRESS_BITS);

        return &mmu->geometry;

fail_l2pts:
        vfree(mmu->l2pts);
fail_l2pt:
        imgu_mmu_free_page_table(mmu->dummy_l2pt);
fail_dummy_page:
        free_page((unsigned long)mmu->dummy_page);
fail_group:
        kfree(mmu);

        return ERR_PTR(-ENOMEM);
}

/**
 * imgu_mmu_exit() - clean up IPU3 MMU block
 *
 * @info: MMU mappable range
 */
void imgu_mmu_exit(struct imgu_mmu_info *info)
{
        struct imgu_mmu *mmu = to_imgu_mmu(info);

        /* We are going to free our page tables, no more memory access. */
        imgu_mmu_set_halt(mmu, true);
        imgu_mmu_tlb_invalidate(mmu);

        imgu_mmu_free_page_table(mmu->l1pt);
        vfree(mmu->l2pts);
        imgu_mmu_free_page_table(mmu->dummy_l2pt);
        free_page((unsigned long)mmu->dummy_page);
        kfree(mmu);
}

void imgu_mmu_suspend(struct imgu_mmu_info *info)
{
        struct imgu_mmu *mmu = to_imgu_mmu(info);

        imgu_mmu_set_halt(mmu, true);
}

void imgu_mmu_resume(struct imgu_mmu_info *info)
{
        struct imgu_mmu *mmu = to_imgu_mmu(info);
        u32 pteval;

        imgu_mmu_set_halt(mmu, true);

        pteval = IPU3_ADDR2PTE(virt_to_phys(mmu->l1pt));
        writel(pteval, mmu->base + REG_L1_PHYS);

        imgu_mmu_tlb_invalidate(mmu);
        imgu_mmu_set_halt(mmu, false);
}