Merge tag 'trace-v5.15-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt...

[mirror_ubuntu-jammy-kernel.git] / drivers / iommu / apple-dart.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Apple DART (Device Address Resolution Table) IOMMU driver
 *
 * Copyright (C) 2021 The Asahi Linux Contributors
 *
 * Based on arm/arm-smmu/arm-ssmu.c and arm/arm-smmu-v3/arm-smmu-v3.c
 *  Copyright (C) 2013 ARM Limited
 *  Copyright (C) 2015 ARM Limited
 * and on exynos-iommu.c
 *  Copyright (c) 2011,2016 Samsung Electronics Co., Ltd.
 */

#include <linux/atomic.h>
#include <linux/bitfield.h>
#include <linux/clk.h>
#include <linux/dev_printk.h>
#include <linux/dma-iommu.h>
#include <linux/dma-mapping.h>
#include <linux/err.h>
#include <linux/interrupt.h>
#include <linux/io-pgtable.h>
#include <linux/iommu.h>
#include <linux/iopoll.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_iommu.h>
#include <linux/of_platform.h>
#include <linux/pci.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/swab.h>
#include <linux/types.h>

#define DART_MAX_STREAMS 16
#define DART_MAX_TTBR 4
#define MAX_DARTS_PER_DEVICE 2

#define DART_STREAM_ALL 0xffff

#define DART_PARAMS1 0x00
#define DART_PARAMS_PAGE_SHIFT GENMASK(27, 24)

#define DART_PARAMS2 0x04
#define DART_PARAMS_BYPASS_SUPPORT BIT(0)

#define DART_STREAM_COMMAND 0x20
#define DART_STREAM_COMMAND_BUSY BIT(2)
#define DART_STREAM_COMMAND_INVALIDATE BIT(20)

#define DART_STREAM_SELECT 0x34

#define DART_ERROR 0x40
#define DART_ERROR_STREAM GENMASK(27, 24)
#define DART_ERROR_CODE GENMASK(11, 0)
#define DART_ERROR_FLAG BIT(31)

#define DART_ERROR_READ_FAULT BIT(4)
#define DART_ERROR_WRITE_FAULT BIT(3)
#define DART_ERROR_NO_PTE BIT(2)
#define DART_ERROR_NO_PMD BIT(1)
#define DART_ERROR_NO_TTBR BIT(0)

#define DART_CONFIG 0x60
#define DART_CONFIG_LOCK BIT(15)

#define DART_STREAM_COMMAND_BUSY_TIMEOUT 100

#define DART_ERROR_ADDR_HI 0x54
#define DART_ERROR_ADDR_LO 0x50

#define DART_TCR(sid) (0x100 + 4 * (sid))
#define DART_TCR_TRANSLATE_ENABLE BIT(7)
#define DART_TCR_BYPASS0_ENABLE BIT(8)
#define DART_TCR_BYPASS1_ENABLE BIT(12)

#define DART_TTBR(sid, idx) (0x200 + 16 * (sid) + 4 * (idx))
#define DART_TTBR_VALID BIT(31)
#define DART_TTBR_SHIFT 12

/*
 * Private structure associated with each DART device.
 *
 * @dev: device struct
 * @regs: mapped MMIO region
 * @irq: interrupt number, can be shared with other DARTs
 * @clks: clocks associated with this DART
 * @num_clks: number of @clks
 * @lock: lock for hardware operations involving this dart
 * @pgsize: pagesize supported by this DART
 * @supports_bypass: indicates if this DART supports bypass mode
 * @force_bypass: force bypass mode due to pagesize mismatch?
 * @sid2group: maps stream ids to iommu_groups
 * @iommu: iommu core device
 */
struct apple_dart {
        struct device *dev;

        void __iomem *regs;

        int irq;
        struct clk_bulk_data *clks;
        int num_clks;

        spinlock_t lock;

        u32 pgsize;
        u32 supports_bypass : 1;
        u32 force_bypass : 1;

        struct iommu_group *sid2group[DART_MAX_STREAMS];
        struct iommu_device iommu;
};

/*
 * Convenience struct to identify streams.
 *
 * The normal variant is used inside apple_dart_master_cfg which isn't written
 * to concurrently.
 * The atomic variant is used inside apple_dart_domain where we have to guard
 * against races from potential parallel calls to attach/detach_device.
 * Note that even inside the atomic variant the apple_dart pointer is not
 * protected: This pointer is initialized once under the domain init mutex
 * and never changed again afterwards. Devices with different dart pointers
 * cannot be attached to the same domain.
 *
 * @dart dart pointer
 * @sid stream id bitmap
 */
struct apple_dart_stream_map {
        struct apple_dart *dart;
        unsigned long sidmap;
};
struct apple_dart_atomic_stream_map {
        struct apple_dart *dart;
        atomic64_t sidmap;
};

/*
 * This structure is attached to each iommu domain handled by a DART.
 *
 * @pgtbl_ops: pagetable ops allocated by io-pgtable
 * @finalized: true if the domain has been completely initialized
 * @init_lock: protects domain initialization
 * @stream_maps: streams attached to this domain (valid for DMA/UNMANAGED only)
 * @domain: core iommu domain pointer
 */
struct apple_dart_domain {
        struct io_pgtable_ops *pgtbl_ops;

        bool finalized;
        struct mutex init_lock;
        struct apple_dart_atomic_stream_map stream_maps[MAX_DARTS_PER_DEVICE];

        struct iommu_domain domain;
};

/*
 * This structure is attached to devices with dev_iommu_priv_set() on of_xlate
 * and contains a list of streams bound to this device.
 * So far the worst case seen is a single device with two streams
 * from different darts, such that this simple static array is enough.
 *
 * @streams: streams for this device
 */
struct apple_dart_master_cfg {
        struct apple_dart_stream_map stream_maps[MAX_DARTS_PER_DEVICE];
};

/*
 * Helper macro to iterate over apple_dart_master_cfg.stream_maps and
 * apple_dart_domain.stream_maps
 *
 * @i int used as loop variable
 * @base pointer to base struct (apple_dart_master_cfg or apple_dart_domain)
 * @stream pointer to the apple_dart_streams struct for each loop iteration
 */
#define for_each_stream_map(i, base, stream_map)                               \
        for (i = 0, stream_map = &(base)->stream_maps[0];                      \
             i < MAX_DARTS_PER_DEVICE && stream_map->dart;                     \
             stream_map = &(base)->stream_maps[++i])

static struct platform_driver apple_dart_driver;
static const struct iommu_ops apple_dart_iommu_ops;

static struct apple_dart_domain *to_dart_domain(struct iommu_domain *dom)
{
        return container_of(dom, struct apple_dart_domain, domain);
}

static void
apple_dart_hw_enable_translation(struct apple_dart_stream_map *stream_map)
{
        int sid;

        for_each_set_bit(sid, &stream_map->sidmap, DART_MAX_STREAMS)
                writel(DART_TCR_TRANSLATE_ENABLE,
                       stream_map->dart->regs + DART_TCR(sid));
}

static void apple_dart_hw_disable_dma(struct apple_dart_stream_map *stream_map)
{
        int sid;

        for_each_set_bit(sid, &stream_map->sidmap, DART_MAX_STREAMS)
                writel(0, stream_map->dart->regs + DART_TCR(sid));
}

static void
apple_dart_hw_enable_bypass(struct apple_dart_stream_map *stream_map)
{
        int sid;

        WARN_ON(!stream_map->dart->supports_bypass);
        for_each_set_bit(sid, &stream_map->sidmap, DART_MAX_STREAMS)
                writel(DART_TCR_BYPASS0_ENABLE | DART_TCR_BYPASS1_ENABLE,
                       stream_map->dart->regs + DART_TCR(sid));
}

static void apple_dart_hw_set_ttbr(struct apple_dart_stream_map *stream_map,
                                   u8 idx, phys_addr_t paddr)
{
        int sid;

        WARN_ON(paddr & ((1 << DART_TTBR_SHIFT) - 1));
        for_each_set_bit(sid, &stream_map->sidmap, DART_MAX_STREAMS)
                writel(DART_TTBR_VALID | (paddr >> DART_TTBR_SHIFT),
                       stream_map->dart->regs + DART_TTBR(sid, idx));
}

static void apple_dart_hw_clear_ttbr(struct apple_dart_stream_map *stream_map,
                                     u8 idx)
{
        int sid;

        for_each_set_bit(sid, &stream_map->sidmap, DART_MAX_STREAMS)
                writel(0, stream_map->dart->regs + DART_TTBR(sid, idx));
}

static void
apple_dart_hw_clear_all_ttbrs(struct apple_dart_stream_map *stream_map)
{
        int i;

        for (i = 0; i < DART_MAX_TTBR; ++i)
                apple_dart_hw_clear_ttbr(stream_map, i);
}

static int
apple_dart_hw_stream_command(struct apple_dart_stream_map *stream_map,
                             u32 command)
{
        unsigned long flags;
        int ret;
        u32 command_reg;

        spin_lock_irqsave(&stream_map->dart->lock, flags);

        writel(stream_map->sidmap, stream_map->dart->regs + DART_STREAM_SELECT);
        writel(command, stream_map->dart->regs + DART_STREAM_COMMAND);

        ret = readl_poll_timeout_atomic(
                stream_map->dart->regs + DART_STREAM_COMMAND, command_reg,
                !(command_reg & DART_STREAM_COMMAND_BUSY), 1,
                DART_STREAM_COMMAND_BUSY_TIMEOUT);

        spin_unlock_irqrestore(&stream_map->dart->lock, flags);

        if (ret) {
                dev_err(stream_map->dart->dev,
                        "busy bit did not clear after command %x for streams %lx\n",
                        command, stream_map->sidmap);
                return ret;
        }

        return 0;
}

static int
apple_dart_hw_invalidate_tlb(struct apple_dart_stream_map *stream_map)
{
        return apple_dart_hw_stream_command(stream_map,
                                            DART_STREAM_COMMAND_INVALIDATE);
}

static int apple_dart_hw_reset(struct apple_dart *dart)
{
        u32 config;
        struct apple_dart_stream_map stream_map;

        config = readl(dart->regs + DART_CONFIG);
        if (config & DART_CONFIG_LOCK) {
                dev_err(dart->dev, "DART is locked down until reboot: %08x\n",
                        config);
                return -EINVAL;
        }

        stream_map.dart = dart;
        stream_map.sidmap = DART_STREAM_ALL;
        apple_dart_hw_disable_dma(&stream_map);
        apple_dart_hw_clear_all_ttbrs(&stream_map);

        /* clear any pending errors before the interrupt is unmasked */
        writel(readl(dart->regs + DART_ERROR), dart->regs + DART_ERROR);

        return apple_dart_hw_invalidate_tlb(&stream_map);
}

static void apple_dart_domain_flush_tlb(struct apple_dart_domain *domain)
{
        int i;
        struct apple_dart_atomic_stream_map *domain_stream_map;
        struct apple_dart_stream_map stream_map;

        for_each_stream_map(i, domain, domain_stream_map) {
                stream_map.dart = domain_stream_map->dart;
                stream_map.sidmap = atomic64_read(&domain_stream_map->sidmap);
                apple_dart_hw_invalidate_tlb(&stream_map);
        }
}

static void apple_dart_flush_iotlb_all(struct iommu_domain *domain)
{
        apple_dart_domain_flush_tlb(to_dart_domain(domain));
}

static void apple_dart_iotlb_sync(struct iommu_domain *domain,
                                  struct iommu_iotlb_gather *gather)
{
        apple_dart_domain_flush_tlb(to_dart_domain(domain));
}

static void apple_dart_iotlb_sync_map(struct iommu_domain *domain,
                                      unsigned long iova, size_t size)
{
        apple_dart_domain_flush_tlb(to_dart_domain(domain));
}

static phys_addr_t apple_dart_iova_to_phys(struct iommu_domain *domain,
                                           dma_addr_t iova)
{
        struct apple_dart_domain *dart_domain = to_dart_domain(domain);
        struct io_pgtable_ops *ops = dart_domain->pgtbl_ops;

        if (!ops)
                return 0;

        return ops->iova_to_phys(ops, iova);
}

static int apple_dart_map_pages(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 apple_dart_domain *dart_domain = to_dart_domain(domain);
        struct io_pgtable_ops *ops = dart_domain->pgtbl_ops;

        if (!ops)
                return -ENODEV;

        return ops->map_pages(ops, iova, paddr, pgsize, pgcount, prot, gfp,
                              mapped);
}

static size_t apple_dart_unmap_pages(struct iommu_domain *domain,
                                     unsigned long iova, size_t pgsize,
                                     size_t pgcount,
                                     struct iommu_iotlb_gather *gather)
{
        struct apple_dart_domain *dart_domain = to_dart_domain(domain);
        struct io_pgtable_ops *ops = dart_domain->pgtbl_ops;

        return ops->unmap_pages(ops, iova, pgsize, pgcount, gather);
}

static void
apple_dart_setup_translation(struct apple_dart_domain *domain,
                             struct apple_dart_stream_map *stream_map)
{
        int i;
        struct io_pgtable_cfg *pgtbl_cfg =
                &io_pgtable_ops_to_pgtable(domain->pgtbl_ops)->cfg;

        for (i = 0; i < pgtbl_cfg->apple_dart_cfg.n_ttbrs; ++i)
                apple_dart_hw_set_ttbr(stream_map, i,
                                       pgtbl_cfg->apple_dart_cfg.ttbr[i]);
        for (; i < DART_MAX_TTBR; ++i)
                apple_dart_hw_clear_ttbr(stream_map, i);

        apple_dart_hw_enable_translation(stream_map);
        apple_dart_hw_invalidate_tlb(stream_map);
}

static int apple_dart_finalize_domain(struct iommu_domain *domain,
                                      struct apple_dart_master_cfg *cfg)
{
        struct apple_dart_domain *dart_domain = to_dart_domain(domain);
        struct apple_dart *dart = cfg->stream_maps[0].dart;
        struct io_pgtable_cfg pgtbl_cfg;
        int ret = 0;
        int i;

        mutex_lock(&dart_domain->init_lock);

        if (dart_domain->finalized)
                goto done;

        for (i = 0; i < MAX_DARTS_PER_DEVICE; ++i) {
                dart_domain->stream_maps[i].dart = cfg->stream_maps[i].dart;
                atomic64_set(&dart_domain->stream_maps[i].sidmap,
                             cfg->stream_maps[i].sidmap);
        }

        pgtbl_cfg = (struct io_pgtable_cfg){
                .pgsize_bitmap = dart->pgsize,
                .ias = 32,
                .oas = 36,
                .coherent_walk = 1,
                .iommu_dev = dart->dev,
        };

        dart_domain->pgtbl_ops =
                alloc_io_pgtable_ops(APPLE_DART, &pgtbl_cfg, domain);
        if (!dart_domain->pgtbl_ops) {
                ret = -ENOMEM;
                goto done;
        }

        domain->pgsize_bitmap = pgtbl_cfg.pgsize_bitmap;
        domain->geometry.aperture_start = 0;
        domain->geometry.aperture_end = DMA_BIT_MASK(32);
        domain->geometry.force_aperture = true;

        dart_domain->finalized = true;

done:
        mutex_unlock(&dart_domain->init_lock);
        return ret;
}

static int
apple_dart_mod_streams(struct apple_dart_atomic_stream_map *domain_maps,
                       struct apple_dart_stream_map *master_maps,
                       bool add_streams)
{
        int i;

        for (i = 0; i < MAX_DARTS_PER_DEVICE; ++i) {
                if (domain_maps[i].dart != master_maps[i].dart)
                        return -EINVAL;
        }

        for (i = 0; i < MAX_DARTS_PER_DEVICE; ++i) {
                if (!domain_maps[i].dart)
                        break;
                if (add_streams)
                        atomic64_or(master_maps[i].sidmap,
                                    &domain_maps[i].sidmap);
                else
                        atomic64_and(~master_maps[i].sidmap,
                                     &domain_maps[i].sidmap);
        }

        return 0;
}

static int apple_dart_domain_add_streams(struct apple_dart_domain *domain,
                                         struct apple_dart_master_cfg *cfg)
{
        return apple_dart_mod_streams(domain->stream_maps, cfg->stream_maps,
                                      true);
}

static int apple_dart_domain_remove_streams(struct apple_dart_domain *domain,
                                            struct apple_dart_master_cfg *cfg)
{
        return apple_dart_mod_streams(domain->stream_maps, cfg->stream_maps,
                                      false);
}

static int apple_dart_attach_dev(struct iommu_domain *domain,
                                 struct device *dev)
{
        int ret, i;
        struct apple_dart_stream_map *stream_map;
        struct apple_dart_master_cfg *cfg = dev_iommu_priv_get(dev);
        struct apple_dart_domain *dart_domain = to_dart_domain(domain);

        if (cfg->stream_maps[0].dart->force_bypass &&
            domain->type != IOMMU_DOMAIN_IDENTITY)
                return -EINVAL;
        if (!cfg->stream_maps[0].dart->supports_bypass &&
            domain->type == IOMMU_DOMAIN_IDENTITY)
                return -EINVAL;

        ret = apple_dart_finalize_domain(domain, cfg);
        if (ret)
                return ret;

        switch (domain->type) {
        case IOMMU_DOMAIN_DMA:
        case IOMMU_DOMAIN_UNMANAGED:
                ret = apple_dart_domain_add_streams(dart_domain, cfg);
                if (ret)
                        return ret;

                for_each_stream_map(i, cfg, stream_map)
                        apple_dart_setup_translation(dart_domain, stream_map);
                break;
        case IOMMU_DOMAIN_BLOCKED:
                for_each_stream_map(i, cfg, stream_map)
                        apple_dart_hw_disable_dma(stream_map);
                break;
        case IOMMU_DOMAIN_IDENTITY:
                for_each_stream_map(i, cfg, stream_map)
                        apple_dart_hw_enable_bypass(stream_map);
                break;
        }

        return ret;
}

static void apple_dart_detach_dev(struct iommu_domain *domain,
                                  struct device *dev)
{
        int i;
        struct apple_dart_stream_map *stream_map;
        struct apple_dart_master_cfg *cfg = dev_iommu_priv_get(dev);
        struct apple_dart_domain *dart_domain = to_dart_domain(domain);

        for_each_stream_map(i, cfg, stream_map)
                apple_dart_hw_disable_dma(stream_map);

        if (domain->type == IOMMU_DOMAIN_DMA ||
            domain->type == IOMMU_DOMAIN_UNMANAGED)
                apple_dart_domain_remove_streams(dart_domain, cfg);
}

static struct iommu_device *apple_dart_probe_device(struct device *dev)
{
        struct apple_dart_master_cfg *cfg = dev_iommu_priv_get(dev);
        struct apple_dart_stream_map *stream_map;
        int i;

        if (!cfg)
                return ERR_PTR(-ENODEV);

        for_each_stream_map(i, cfg, stream_map)
                device_link_add(
                        dev, stream_map->dart->dev,
                        DL_FLAG_PM_RUNTIME | DL_FLAG_AUTOREMOVE_SUPPLIER);

        return &cfg->stream_maps[0].dart->iommu;
}

static void apple_dart_release_device(struct device *dev)
{
        struct apple_dart_master_cfg *cfg = dev_iommu_priv_get(dev);

        if (!cfg)
                return;

        dev_iommu_priv_set(dev, NULL);
        kfree(cfg);
}

static struct iommu_domain *apple_dart_domain_alloc(unsigned int type)
{
        struct apple_dart_domain *dart_domain;

        if (type != IOMMU_DOMAIN_DMA && type != IOMMU_DOMAIN_UNMANAGED &&
            type != IOMMU_DOMAIN_IDENTITY && type != IOMMU_DOMAIN_BLOCKED)
                return NULL;

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

        iommu_get_dma_cookie(&dart_domain->domain);
        mutex_init(&dart_domain->init_lock);

        /* no need to allocate pgtbl_ops or do any other finalization steps */
        if (type == IOMMU_DOMAIN_IDENTITY || type == IOMMU_DOMAIN_BLOCKED)
                dart_domain->finalized = true;

        return &dart_domain->domain;
}

static void apple_dart_domain_free(struct iommu_domain *domain)
{
        struct apple_dart_domain *dart_domain = to_dart_domain(domain);

        if (dart_domain->pgtbl_ops)
                free_io_pgtable_ops(dart_domain->pgtbl_ops);

        kfree(dart_domain);
}

static int apple_dart_of_xlate(struct device *dev, struct of_phandle_args *args)
{
        struct apple_dart_master_cfg *cfg = dev_iommu_priv_get(dev);
        struct platform_device *iommu_pdev = of_find_device_by_node(args->np);
        struct apple_dart *dart = platform_get_drvdata(iommu_pdev);
        struct apple_dart *cfg_dart;
        int i, sid;

        if (args->args_count != 1)
                return -EINVAL;
        sid = args->args[0];

        if (!cfg)
                cfg = kzalloc(sizeof(*cfg), GFP_KERNEL);
        if (!cfg)
                return -ENOMEM;
        dev_iommu_priv_set(dev, cfg);

        cfg_dart = cfg->stream_maps[0].dart;
        if (cfg_dart) {
                if (cfg_dart->supports_bypass != dart->supports_bypass)
                        return -EINVAL;
                if (cfg_dart->force_bypass != dart->force_bypass)
                        return -EINVAL;
                if (cfg_dart->pgsize != dart->pgsize)
                        return -EINVAL;
        }

        for (i = 0; i < MAX_DARTS_PER_DEVICE; ++i) {
                if (cfg->stream_maps[i].dart == dart) {
                        cfg->stream_maps[i].sidmap |= 1 << sid;
                        return 0;
                }
        }
        for (i = 0; i < MAX_DARTS_PER_DEVICE; ++i) {
                if (!cfg->stream_maps[i].dart) {
                        cfg->stream_maps[i].dart = dart;
                        cfg->stream_maps[i].sidmap = 1 << sid;
                        return 0;
                }
        }

        return -EINVAL;
}

static DEFINE_MUTEX(apple_dart_groups_lock);

static void apple_dart_release_group(void *iommu_data)
{
        int i, sid;
        struct apple_dart_stream_map *stream_map;
        struct apple_dart_master_cfg *group_master_cfg = iommu_data;

        mutex_lock(&apple_dart_groups_lock);

        for_each_stream_map(i, group_master_cfg, stream_map)
                for_each_set_bit(sid, &stream_map->sidmap, DART_MAX_STREAMS)
                        stream_map->dart->sid2group[sid] = NULL;

        kfree(iommu_data);
        mutex_unlock(&apple_dart_groups_lock);
}

static struct iommu_group *apple_dart_device_group(struct device *dev)
{
        int i, sid;
        struct apple_dart_master_cfg *cfg = dev_iommu_priv_get(dev);
        struct apple_dart_stream_map *stream_map;
        struct apple_dart_master_cfg *group_master_cfg;
        struct iommu_group *group = NULL;
        struct iommu_group *res = ERR_PTR(-EINVAL);

        mutex_lock(&apple_dart_groups_lock);

        for_each_stream_map(i, cfg, stream_map) {
                for_each_set_bit(sid, &stream_map->sidmap, DART_MAX_STREAMS) {
                        struct iommu_group *stream_group =
                                stream_map->dart->sid2group[sid];

                        if (group && group != stream_group) {
                                res = ERR_PTR(-EINVAL);
                                goto out;
                        }

                        group = stream_group;
                }
        }

        if (group) {
                res = iommu_group_ref_get(group);
                goto out;
        }

#ifdef CONFIG_PCI
        if (dev_is_pci(dev))
                group = pci_device_group(dev);
        else
#endif
                group = generic_device_group(dev);

        res = ERR_PTR(-ENOMEM);
        if (!group)
                goto out;

        group_master_cfg = kzalloc(sizeof(*group_master_cfg), GFP_KERNEL);
        if (!group_master_cfg) {
                iommu_group_put(group);
                goto out;
        }

        memcpy(group_master_cfg, cfg, sizeof(*group_master_cfg));
        iommu_group_set_iommudata(group, group_master_cfg,
                apple_dart_release_group);

        for_each_stream_map(i, cfg, stream_map)
                for_each_set_bit(sid, &stream_map->sidmap, DART_MAX_STREAMS)
                        stream_map->dart->sid2group[sid] = group;

        res = group;

out:
        mutex_unlock(&apple_dart_groups_lock);
        return res;
}

static int apple_dart_def_domain_type(struct device *dev)
{
        struct apple_dart_master_cfg *cfg = dev_iommu_priv_get(dev);

        if (cfg->stream_maps[0].dart->force_bypass)
                return IOMMU_DOMAIN_IDENTITY;
        if (!cfg->stream_maps[0].dart->supports_bypass)
                return IOMMU_DOMAIN_DMA;

        return 0;
}

static const struct iommu_ops apple_dart_iommu_ops = {
        .domain_alloc = apple_dart_domain_alloc,
        .domain_free = apple_dart_domain_free,
        .attach_dev = apple_dart_attach_dev,
        .detach_dev = apple_dart_detach_dev,
        .map_pages = apple_dart_map_pages,
        .unmap_pages = apple_dart_unmap_pages,
        .flush_iotlb_all = apple_dart_flush_iotlb_all,
        .iotlb_sync = apple_dart_iotlb_sync,
        .iotlb_sync_map = apple_dart_iotlb_sync_map,
        .iova_to_phys = apple_dart_iova_to_phys,
        .probe_device = apple_dart_probe_device,
        .release_device = apple_dart_release_device,
        .device_group = apple_dart_device_group,
        .of_xlate = apple_dart_of_xlate,
        .def_domain_type = apple_dart_def_domain_type,
        .pgsize_bitmap = -1UL, /* Restricted during dart probe */
};

static irqreturn_t apple_dart_irq(int irq, void *dev)
{
        struct apple_dart *dart = dev;
        const char *fault_name = NULL;
        u32 error = readl(dart->regs + DART_ERROR);
        u32 error_code = FIELD_GET(DART_ERROR_CODE, error);
        u32 addr_lo = readl(dart->regs + DART_ERROR_ADDR_LO);
        u32 addr_hi = readl(dart->regs + DART_ERROR_ADDR_HI);
        u64 addr = addr_lo | (((u64)addr_hi) << 32);
        u8 stream_idx = FIELD_GET(DART_ERROR_STREAM, error);

        if (!(error & DART_ERROR_FLAG))
                return IRQ_NONE;

        /* there should only be a single bit set but let's use == to be sure */
        if (error_code == DART_ERROR_READ_FAULT)
                fault_name = "READ FAULT";
        else if (error_code == DART_ERROR_WRITE_FAULT)
                fault_name = "WRITE FAULT";
        else if (error_code == DART_ERROR_NO_PTE)
                fault_name = "NO PTE FOR IOVA";
        else if (error_code == DART_ERROR_NO_PMD)
                fault_name = "NO PMD FOR IOVA";
        else if (error_code == DART_ERROR_NO_TTBR)
                fault_name = "NO TTBR FOR IOVA";
        else
                fault_name = "unknown";

        dev_err_ratelimited(
                dart->dev,
                "translation fault: status:0x%x stream:%d code:0x%x (%s) at 0x%llx",
                error, stream_idx, error_code, fault_name, addr);

        writel(error, dart->regs + DART_ERROR);
        return IRQ_HANDLED;
}

static int apple_dart_set_bus_ops(const struct iommu_ops *ops)
{
        int ret;

        if (!iommu_present(&platform_bus_type)) {
                ret = bus_set_iommu(&platform_bus_type, ops);
                if (ret)
                        return ret;
        }
#ifdef CONFIG_PCI
        if (!iommu_present(&pci_bus_type)) {
                ret = bus_set_iommu(&pci_bus_type, ops);
                if (ret) {
                        bus_set_iommu(&platform_bus_type, NULL);
                        return ret;
                }
        }
#endif
        return 0;
}

static int apple_dart_probe(struct platform_device *pdev)
{
        int ret;
        u32 dart_params[2];
        struct resource *res;
        struct apple_dart *dart;
        struct device *dev = &pdev->dev;

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

        dart->dev = dev;
        spin_lock_init(&dart->lock);

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (resource_size(res) < 0x4000) {
                dev_err(dev, "MMIO region too small (%pr)\n", res);
                return -EINVAL;
        }

        dart->regs = devm_ioremap_resource(dev, res);
        if (IS_ERR(dart->regs))
                return PTR_ERR(dart->regs);

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

        ret = devm_clk_bulk_get_all(dev, &dart->clks);
        if (ret < 0)
                return ret;
        dart->num_clks = ret;

        ret = clk_bulk_prepare_enable(dart->num_clks, dart->clks);
        if (ret)
                return ret;

        ret = apple_dart_hw_reset(dart);
        if (ret)
                goto err_clk_disable;

        dart_params[0] = readl(dart->regs + DART_PARAMS1);
        dart_params[1] = readl(dart->regs + DART_PARAMS2);
        dart->pgsize = 1 << FIELD_GET(DART_PARAMS_PAGE_SHIFT, dart_params[0]);
        dart->supports_bypass = dart_params[1] & DART_PARAMS_BYPASS_SUPPORT;
        dart->force_bypass = dart->pgsize > PAGE_SIZE;

        ret = request_irq(dart->irq, apple_dart_irq, IRQF_SHARED,
                          "apple-dart fault handler", dart);
        if (ret)
                goto err_clk_disable;

        platform_set_drvdata(pdev, dart);

        ret = apple_dart_set_bus_ops(&apple_dart_iommu_ops);
        if (ret)
                goto err_free_irq;

        ret = iommu_device_sysfs_add(&dart->iommu, dev, NULL, "apple-dart.%s",
                                     dev_name(&pdev->dev));
        if (ret)
                goto err_remove_bus_ops;

        ret = iommu_device_register(&dart->iommu, &apple_dart_iommu_ops, dev);
        if (ret)
                goto err_sysfs_remove;

        dev_info(
                &pdev->dev,
                "DART [pagesize %x, bypass support: %d, bypass forced: %d] initialized\n",
                dart->pgsize, dart->supports_bypass, dart->force_bypass);
        return 0;

err_sysfs_remove:
        iommu_device_sysfs_remove(&dart->iommu);
err_remove_bus_ops:
        apple_dart_set_bus_ops(NULL);
err_free_irq:
        free_irq(dart->irq, dart);
err_clk_disable:
        clk_bulk_disable_unprepare(dart->num_clks, dart->clks);

        return ret;
}

static int apple_dart_remove(struct platform_device *pdev)
{
        struct apple_dart *dart = platform_get_drvdata(pdev);

        apple_dart_hw_reset(dart);
        free_irq(dart->irq, dart);
        apple_dart_set_bus_ops(NULL);

        iommu_device_unregister(&dart->iommu);
        iommu_device_sysfs_remove(&dart->iommu);

        clk_bulk_disable_unprepare(dart->num_clks, dart->clks);

        return 0;
}

static const struct of_device_id apple_dart_of_match[] = {
        { .compatible = "apple,t8103-dart", .data = NULL },
        {},
};
MODULE_DEVICE_TABLE(of, apple_dart_of_match);

static struct platform_driver apple_dart_driver = {
        .driver = {
                .name                   = "apple-dart",
                .of_match_table         = apple_dart_of_match,
                .suppress_bind_attrs    = true,
        },
        .probe  = apple_dart_probe,
        .remove = apple_dart_remove,
};

module_platform_driver(apple_dart_driver);

MODULE_DESCRIPTION("IOMMU API for Apple's DART");
MODULE_AUTHOR("Sven Peter <sven@svenpeter.dev>");
MODULE_LICENSE("GPL v2");