// SPDX-License-Identifier: GPL-2.0-only
/*
 * Unisoc IOMMU driver
 *
 * Copyright (C) 2020 Unisoc, Inc.
 * Author: Chunyan Zhang <chunyan.zhang@unisoc.com>
 */

#include <linux/clk.h>
#include <linux/device.h>
#include <linux/dma-mapping.h>
#include <linux/errno.h>
#include <linux/iommu.h>
#include <linux/mfd/syscon.h>
#include <linux/module.h>
#include <linux/of_platform.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>
#include <linux/slab.h>

#define SPRD_IOMMU_PAGE_SHIFT   12
#define SPRD_IOMMU_PAGE_SIZE    SZ_4K

#define SPRD_EX_CFG             0x0
#define SPRD_IOMMU_VAOR_BYPASS  BIT(4)
#define SPRD_IOMMU_GATE_EN      BIT(1)
#define SPRD_IOMMU_EN           BIT(0)
#define SPRD_EX_UPDATE          0x4
#define SPRD_EX_FIRST_VPN       0x8
#define SPRD_EX_VPN_RANGE       0xc
#define SPRD_EX_FIRST_PPN       0x10
#define SPRD_EX_DEFAULT_PPN     0x14

#define SPRD_IOMMU_VERSION      0x0
#define SPRD_VERSION_MASK       GENMASK(15, 8)
#define SPRD_VERSION_SHIFT      0x8
#define SPRD_VAU_CFG            0x4
#define SPRD_VAU_UPDATE         0x8
#define SPRD_VAU_AUTH_CFG       0xc
#define SPRD_VAU_FIRST_PPN      0x10
#define SPRD_VAU_DEFAULT_PPN_RD 0x14
#define SPRD_VAU_DEFAULT_PPN_WR 0x18
#define SPRD_VAU_FIRST_VPN      0x1c
#define SPRD_VAU_VPN_RANGE      0x20

enum sprd_iommu_version {
        SPRD_IOMMU_EX,
        SPRD_IOMMU_VAU,
};

/*
 * struct sprd_iommu_device - high-level sprd IOMMU device representation,
 * including hardware information and configuration, also driver data, etc
 *
 * @ver: sprd IOMMU IP version
 * @prot_page_va: protect page base virtual address
 * @prot_page_pa: protect page base physical address, data would be
 *                written to here while translation fault
 * @base: mapped base address for accessing registers
 * @dev: pointer to basic device structure
 * @iommu: IOMMU core representation
 * @group: IOMMU group
 * @eb: gate clock which controls IOMMU access
 */
struct sprd_iommu_device {
        struct sprd_iommu_domain        *dom;
        enum sprd_iommu_version ver;
        u32                     *prot_page_va;
        dma_addr_t              prot_page_pa;
        void __iomem            *base;
        struct device           *dev;
        struct iommu_device     iommu;
        struct clk              *eb;
};

struct sprd_iommu_domain {
        spinlock_t              pgtlock; /* lock for page table */
        struct iommu_domain     domain;
        u32                     *pgt_va; /* page table virtual address base */
        dma_addr_t              pgt_pa; /* page table physical address base */
        struct sprd_iommu_device        *sdev;
};

static const struct iommu_ops sprd_iommu_ops;

static struct sprd_iommu_domain *to_sprd_domain(struct iommu_domain *dom)
{
        return container_of(dom, struct sprd_iommu_domain, domain);
}

static inline void
sprd_iommu_write(struct sprd_iommu_device *sdev, unsigned int reg, u32 val)
{
        writel_relaxed(val, sdev->base + reg);
}

static inline u32
sprd_iommu_read(struct sprd_iommu_device *sdev, unsigned int reg)
{
        return readl_relaxed(sdev->base + reg);
}

static inline void
sprd_iommu_update_bits(struct sprd_iommu_device *sdev, unsigned int reg,
                  u32 mask, u32 shift, u32 val)
{
        u32 t = sprd_iommu_read(sdev, reg);

        t = (t & (~(mask << shift))) | ((val & mask) << shift);
        sprd_iommu_write(sdev, reg, t);
}

static inline int
sprd_iommu_get_version(struct sprd_iommu_device *sdev)
{
        int ver = (sprd_iommu_read(sdev, SPRD_IOMMU_VERSION) &
                   SPRD_VERSION_MASK) >> SPRD_VERSION_SHIFT;

        switch (ver) {
        case SPRD_IOMMU_EX:
        case SPRD_IOMMU_VAU:
                return ver;
        default:
                return -EINVAL;
        }
}

static size_t
sprd_iommu_pgt_size(struct iommu_domain *domain)
{
        return ((domain->geometry.aperture_end -
                 domain->geometry.aperture_start + 1) >>
                SPRD_IOMMU_PAGE_SHIFT) * sizeof(u32);
}

static struct iommu_domain *sprd_iommu_domain_alloc_paging(struct device *dev)
{
        struct sprd_iommu_domain *dom;

        dom = kzalloc_obj(*dom);
        if (!dom)
                return NULL;

        spin_lock_init(&dom->pgtlock);

        dom->domain.pgsize_bitmap = SPRD_IOMMU_PAGE_SIZE;

        dom->domain.geometry.aperture_start = 0;
        dom->domain.geometry.aperture_end = SZ_256M - 1;
        dom->domain.geometry.force_aperture = true;

        return &dom->domain;
}

static void sprd_iommu_first_vpn(struct sprd_iommu_domain *dom)
{
        struct sprd_iommu_device *sdev = dom->sdev;
        u32 val;
        unsigned int reg;

        if (sdev->ver == SPRD_IOMMU_EX)
                reg = SPRD_EX_FIRST_VPN;
        else
                reg = SPRD_VAU_FIRST_VPN;

        val = dom->domain.geometry.aperture_start >> SPRD_IOMMU_PAGE_SHIFT;
        sprd_iommu_write(sdev, reg, val);
}

static void sprd_iommu_vpn_range(struct sprd_iommu_domain *dom)
{
        struct sprd_iommu_device *sdev = dom->sdev;
        u32 val;
        unsigned int reg;

        if (sdev->ver == SPRD_IOMMU_EX)
                reg = SPRD_EX_VPN_RANGE;
        else
                reg = SPRD_VAU_VPN_RANGE;

        val = (dom->domain.geometry.aperture_end -
               dom->domain.geometry.aperture_start) >> SPRD_IOMMU_PAGE_SHIFT;
        sprd_iommu_write(sdev, reg, val);
}

static void sprd_iommu_first_ppn(struct sprd_iommu_domain *dom)
{
        u32 val = dom->pgt_pa >> SPRD_IOMMU_PAGE_SHIFT;
        struct sprd_iommu_device *sdev = dom->sdev;
        unsigned int reg;

        if (sdev->ver == SPRD_IOMMU_EX)
                reg = SPRD_EX_FIRST_PPN;
        else
                reg = SPRD_VAU_FIRST_PPN;

        sprd_iommu_write(sdev, reg, val);
}

static void sprd_iommu_default_ppn(struct sprd_iommu_device *sdev)
{
        u32 val = sdev->prot_page_pa >> SPRD_IOMMU_PAGE_SHIFT;

        if (sdev->ver == SPRD_IOMMU_EX) {
                sprd_iommu_write(sdev, SPRD_EX_DEFAULT_PPN, val);
        } else if (sdev->ver == SPRD_IOMMU_VAU) {
                sprd_iommu_write(sdev, SPRD_VAU_DEFAULT_PPN_RD, val);
                sprd_iommu_write(sdev, SPRD_VAU_DEFAULT_PPN_WR, val);
        }
}

static void sprd_iommu_hw_en(struct sprd_iommu_device *sdev, bool en)
{
        unsigned int reg_cfg;
        u32 mask, val;

        if (sdev->ver == SPRD_IOMMU_EX)
                reg_cfg = SPRD_EX_CFG;
        else
                reg_cfg = SPRD_VAU_CFG;

        mask = SPRD_IOMMU_EN | SPRD_IOMMU_GATE_EN;
        val = en ? mask : 0;
        sprd_iommu_update_bits(sdev, reg_cfg, mask, 0, val);
}

static void sprd_iommu_cleanup(struct sprd_iommu_domain *dom)
{
        size_t pgt_size;

        /* Nothing need to do if the domain hasn't been attached */
        if (!dom->sdev)
                return;

        pgt_size = sprd_iommu_pgt_size(&dom->domain);
        dma_free_coherent(dom->sdev->dev, pgt_size, dom->pgt_va, dom->pgt_pa);
        sprd_iommu_hw_en(dom->sdev, false);
        dom->sdev = NULL;
}

static void sprd_iommu_domain_free(struct iommu_domain *domain)
{
        struct sprd_iommu_domain *dom = to_sprd_domain(domain);

        sprd_iommu_cleanup(dom);
        kfree(dom);
}

static int sprd_iommu_attach_device(struct iommu_domain *domain,
                                    struct device *dev,
                                    struct iommu_domain *old)
{
        struct sprd_iommu_device *sdev = dev_iommu_priv_get(dev);
        struct sprd_iommu_domain *dom = to_sprd_domain(domain);
        size_t pgt_size = sprd_iommu_pgt_size(domain);

        /* The device is attached to this domain */
        if (sdev->dom == dom)
                return 0;

        /* The first time that domain is attaching to a device */
        if (!dom->pgt_va) {
                dom->pgt_va = dma_alloc_coherent(sdev->dev, pgt_size, &dom->pgt_pa, GFP_KERNEL);
                if (!dom->pgt_va)
                        return -ENOMEM;

                dom->sdev = sdev;
        }

        sdev->dom = dom;

        /*
         * One sprd IOMMU serves one client device only, disabled it before
         * configure mapping table to avoid access conflict in case other
         * mapping table is stored in.
         */
        sprd_iommu_hw_en(sdev, false);
        sprd_iommu_first_ppn(dom);
        sprd_iommu_first_vpn(dom);
        sprd_iommu_vpn_range(dom);
        sprd_iommu_default_ppn(sdev);
        sprd_iommu_hw_en(sdev, true);

        return 0;
}

static int sprd_iommu_map(struct iommu_domain *domain, unsigned long iova,
                          phys_addr_t paddr, size_t pgsize, size_t pgcount,
                          int prot, gfp_t gfp, size_t *mapped)
{
        struct sprd_iommu_domain *dom = to_sprd_domain(domain);
        size_t size = pgcount * SPRD_IOMMU_PAGE_SIZE;
        unsigned long flags;
        unsigned int i;
        u32 *pgt_base_iova;
        u32 pabase = (u32)paddr;
        unsigned long start = domain->geometry.aperture_start;
        unsigned long end = domain->geometry.aperture_end;

        if (!dom->sdev) {
                pr_err("No sprd_iommu_device attached to the domain\n");
                return -EINVAL;
        }

        if (iova < start || (iova + size) > (end + 1)) {
                dev_err(dom->sdev->dev, "(iova(0x%lx) + size(%zx)) are not in the range!\n",
                        iova, size);
                return -EINVAL;
        }

        pgt_base_iova = dom->pgt_va + ((iova - start) >> SPRD_IOMMU_PAGE_SHIFT);

        spin_lock_irqsave(&dom->pgtlock, flags);
        for (i = 0; i < pgcount; i++) {
                pgt_base_iova[i] = pabase >> SPRD_IOMMU_PAGE_SHIFT;
                pabase += SPRD_IOMMU_PAGE_SIZE;
        }
        spin_unlock_irqrestore(&dom->pgtlock, flags);

        *mapped = size;
        return 0;
}

static size_t sprd_iommu_unmap(struct iommu_domain *domain, unsigned long iova,
                               size_t pgsize, size_t pgcount,
                               struct iommu_iotlb_gather *iotlb_gather)
{
        struct sprd_iommu_domain *dom = to_sprd_domain(domain);
        unsigned long flags;
        u32 *pgt_base_iova;
        size_t size = pgcount * SPRD_IOMMU_PAGE_SIZE;
        unsigned long start = domain->geometry.aperture_start;
        unsigned long end = domain->geometry.aperture_end;

        if (iova < start || (iova + size) > (end + 1))
                return 0;

        pgt_base_iova = dom->pgt_va + ((iova - start) >> SPRD_IOMMU_PAGE_SHIFT);

        spin_lock_irqsave(&dom->pgtlock, flags);
        memset(pgt_base_iova, 0, pgcount * sizeof(u32));
        spin_unlock_irqrestore(&dom->pgtlock, flags);

        return size;
}

static int sprd_iommu_sync_map(struct iommu_domain *domain,
                               unsigned long iova, size_t size)
{
        struct sprd_iommu_domain *dom = to_sprd_domain(domain);
        unsigned int reg;

        if (dom->sdev->ver == SPRD_IOMMU_EX)
                reg = SPRD_EX_UPDATE;
        else
                reg = SPRD_VAU_UPDATE;

        /* clear IOMMU TLB buffer after page table updated */
        sprd_iommu_write(dom->sdev, reg, 0xffffffff);
        return 0;
}

static void sprd_iommu_sync(struct iommu_domain *domain,
                            struct iommu_iotlb_gather *iotlb_gather)
{
        sprd_iommu_sync_map(domain, 0, 0);
}

static phys_addr_t sprd_iommu_iova_to_phys(struct iommu_domain *domain,
                                           dma_addr_t iova)
{
        struct sprd_iommu_domain *dom = to_sprd_domain(domain);
        unsigned long flags;
        phys_addr_t pa;
        unsigned long start = domain->geometry.aperture_start;
        unsigned long end = domain->geometry.aperture_end;

        if (WARN_ON(iova < start || iova > end))
                return 0;

        spin_lock_irqsave(&dom->pgtlock, flags);
        pa = *(dom->pgt_va + ((iova - start) >> SPRD_IOMMU_PAGE_SHIFT));
        pa = (pa << SPRD_IOMMU_PAGE_SHIFT) + ((iova - start) & (SPRD_IOMMU_PAGE_SIZE - 1));
        spin_unlock_irqrestore(&dom->pgtlock, flags);

        return pa;
}

static struct iommu_device *sprd_iommu_probe_device(struct device *dev)
{
        struct sprd_iommu_device *sdev = dev_iommu_priv_get(dev);

        return &sdev->iommu;
}

static int sprd_iommu_of_xlate(struct device *dev,
                               const struct of_phandle_args *args)
{
        struct platform_device *pdev;

        if (!dev_iommu_priv_get(dev)) {
                pdev = of_find_device_by_node(args->np);
                dev_iommu_priv_set(dev, platform_get_drvdata(pdev));
                platform_device_put(pdev);
        }

        return 0;
}


static const struct iommu_ops sprd_iommu_ops = {
        .domain_alloc_paging = sprd_iommu_domain_alloc_paging,
        .probe_device   = sprd_iommu_probe_device,
        .device_group   = generic_single_device_group,
        .of_xlate       = sprd_iommu_of_xlate,
        .owner          = THIS_MODULE,
        .default_domain_ops = &(const struct iommu_domain_ops) {
                .attach_dev     = sprd_iommu_attach_device,
                .map_pages      = sprd_iommu_map,
                .unmap_pages    = sprd_iommu_unmap,
                .iotlb_sync_map = sprd_iommu_sync_map,
                .iotlb_sync     = sprd_iommu_sync,
                .iova_to_phys   = sprd_iommu_iova_to_phys,
                .free           = sprd_iommu_domain_free,
        }
};

static const struct of_device_id sprd_iommu_of_match[] = {
        { .compatible = "sprd,iommu-v1" },
        { },
};
MODULE_DEVICE_TABLE(of, sprd_iommu_of_match);

/*
 * Clock is not required, access to some of IOMMUs is controlled by gate
 * clk, enabled clocks for that kind of IOMMUs before accessing.
 * Return 0 for success or no clocks found.
 */
static int sprd_iommu_clk_enable(struct sprd_iommu_device *sdev)
{
        struct clk *eb;

        eb = devm_clk_get_optional(sdev->dev, NULL);
        if (!eb)
                return 0;

        if (IS_ERR(eb))
                return PTR_ERR(eb);

        sdev->eb = eb;
        return clk_prepare_enable(eb);
}

static void sprd_iommu_clk_disable(struct sprd_iommu_device *sdev)
{
        if (sdev->eb)
                clk_disable_unprepare(sdev->eb);
}

static int sprd_iommu_probe(struct platform_device *pdev)
{
        struct sprd_iommu_device *sdev;
        struct device *dev = &pdev->dev;
        void __iomem *base;
        int ret;

        sdev = devm_kzalloc(dev, sizeof(*sdev), GFP_KERNEL);
        if (!sdev)
                return -ENOMEM;

        base = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(base)) {
                dev_err(dev, "Failed to get ioremap resource.\n");
                return PTR_ERR(base);
        }
        sdev->base = base;

        sdev->prot_page_va = dma_alloc_coherent(dev, SPRD_IOMMU_PAGE_SIZE,
                                                &sdev->prot_page_pa, GFP_KERNEL);
        if (!sdev->prot_page_va)
                return -ENOMEM;

        platform_set_drvdata(pdev, sdev);
        sdev->dev = dev;

        ret = iommu_device_sysfs_add(&sdev->iommu, dev, NULL, dev_name(dev));
        if (ret)
                goto free_page;

        ret = iommu_device_register(&sdev->iommu, &sprd_iommu_ops, dev);
        if (ret)
                goto remove_sysfs;

        ret = sprd_iommu_clk_enable(sdev);
        if (ret)
                goto unregister_iommu;

        ret = sprd_iommu_get_version(sdev);
        if (ret < 0) {
                dev_err(dev, "IOMMU version(%d) is invalid.\n", ret);
                goto disable_clk;
        }
        sdev->ver = ret;

        return 0;

disable_clk:
        sprd_iommu_clk_disable(sdev);
unregister_iommu:
        iommu_device_unregister(&sdev->iommu);
remove_sysfs:
        iommu_device_sysfs_remove(&sdev->iommu);
free_page:
        dma_free_coherent(sdev->dev, SPRD_IOMMU_PAGE_SIZE, sdev->prot_page_va, sdev->prot_page_pa);
        return ret;
}

static void sprd_iommu_remove(struct platform_device *pdev)
{
        struct sprd_iommu_device *sdev = platform_get_drvdata(pdev);

        dma_free_coherent(sdev->dev, SPRD_IOMMU_PAGE_SIZE, sdev->prot_page_va, sdev->prot_page_pa);

        platform_set_drvdata(pdev, NULL);
        iommu_device_sysfs_remove(&sdev->iommu);
        iommu_device_unregister(&sdev->iommu);
}

static struct platform_driver sprd_iommu_driver = {
        .driver = {
                .name           = "sprd-iommu",
                .of_match_table = sprd_iommu_of_match,
                .suppress_bind_attrs = true,
        },
        .probe  = sprd_iommu_probe,
        .remove = sprd_iommu_remove,
};
module_platform_driver(sprd_iommu_driver);

MODULE_DESCRIPTION("IOMMU driver for Unisoc SoCs");
MODULE_ALIAS("platform:sprd-iommu");
MODULE_LICENSE("GPL");