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From:   Sven Peter <sven@svenpeter.dev>
To:     Will Deacon <will@kernel.org>, Robin Murphy <robin.murphy@arm.com>,
        Joerg Roedel <joro@8bytes.org>
Cc:     Sven Peter <sven@svenpeter.dev>, Arnd Bergmann <arnd@kernel.org>,
        devicetree@vger.kernel.org, Hector Martin <marcan@marcan.st>,
        linux-kernel@vger.kernel.org, Marc Zyngier <maz@kernel.org>,
        Mohamed Mediouni <mohamed.mediouni@caramail.com>,
        Stan Skowronek <stan@corellium.com>,
        linux-arm-kernel@lists.infradead.org,
        Mark Kettenis <mark.kettenis@xs4all.nl>,
        iommu@lists.linux-foundation.org, Alexander Graf <graf@amazon.com>,
        Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>,
        Rob Herring <robh+dt@kernel.org>, r.czerwinski@pengutronix.de
Subject: [PATCH v4 3/3] iommu: dart: Add DART iommu driver
Date:   Sun, 27 Jun 2021 16:34:05 +0200
Message-Id: <20210627143405.77298-4-sven@svenpeter.dev>
In-Reply-To: <20210627143405.77298-1-sven@svenpeter.dev>
References: <20210627143405.77298-1-sven@svenpeter.dev>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
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Apple's new SoCs use iommus for almost all peripherals. These Device
Address Resolution Tables must be setup before these peripherals can
act as DMA masters.

Signed-off-by: Sven Peter <sven@svenpeter.dev>
---
 MAINTAINERS                      |    1 +
 drivers/iommu/Kconfig            |   15 +
 drivers/iommu/Makefile           |    1 +
 drivers/iommu/apple-dart-iommu.c | 1058 ++++++++++++++++++++++++++++++
 4 files changed, 1075 insertions(+)
 create mode 100644 drivers/iommu/apple-dart-iommu.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 29e5541c8f21..c1ffaa56b5f9 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1245,6 +1245,7 @@ M:	Sven Peter <sven@svenpeter.dev>
 L:	iommu@lists.linux-foundation.org
 S:	Maintained
 F:	Documentation/devicetree/bindings/iommu/apple,dart.yaml
+F:	drivers/iommu/apple-dart-iommu.c
 
 APPLE SMC DRIVER
 M:	Henrik Rydberg <rydberg@bitmath.org>
diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
index 1f111b399bca..87882c628b46 100644
--- a/drivers/iommu/Kconfig
+++ b/drivers/iommu/Kconfig
@@ -249,6 +249,21 @@ config SPAPR_TCE_IOMMU
 	  Enables bits of IOMMU API required by VFIO. The iommu_ops
 	  is not implemented as it is not necessary for VFIO.
 
+config IOMMU_APPLE_DART
+	tristate "Apple DART IOMMU Support"
+	depends on ARM64 || (COMPILE_TEST && !GENERIC_ATOMIC64)
+	select IOMMU_API
+	select IOMMU_IO_PGTABLE
+	select IOMMU_IO_PGTABLE_LPAE
+	default ARCH_APPLE
+	help
+	  Support for Apple DART (Device Address Resolution Table) IOMMUs
+	  found in Apple ARM SoCs like the M1.
+	  This IOMMU is required for most peripherals using DMA to access
+	  the main memory.
+
+	  Say Y here if you are using an Apple SoC with a DART IOMMU.
+
 # ARM IOMMU support
 config ARM_SMMU
 	tristate "ARM Ltd. System MMU (SMMU) Support"
diff --git a/drivers/iommu/Makefile b/drivers/iommu/Makefile
index c0fb0ba88143..8c813f0ebc54 100644
--- a/drivers/iommu/Makefile
+++ b/drivers/iommu/Makefile
@@ -29,3 +29,4 @@ obj-$(CONFIG_HYPERV_IOMMU) += hyperv-iommu.o
 obj-$(CONFIG_VIRTIO_IOMMU) += virtio-iommu.o
 obj-$(CONFIG_IOMMU_SVA_LIB) += iommu-sva-lib.o io-pgfault.o
 obj-$(CONFIG_SPRD_IOMMU) += sprd-iommu.o
+obj-$(CONFIG_IOMMU_APPLE_DART) += apple-dart-iommu.o
diff --git a/drivers/iommu/apple-dart-iommu.c b/drivers/iommu/apple-dart-iommu.c
new file mode 100644
index 000000000000..637ba6e7cef9
--- /dev/null
+++ b/drivers/iommu/apple-dart-iommu.c
@@ -0,0 +1,1058 @@
+// 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/bitfield.h>
+#include <linux/clk.h>
+#include <linux/dma-direct.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/iopoll.h>
+#include <linux/list.h>
+#include <linux/lockdep.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/ratelimit.h>
+#include <linux/slab.h>
+#include <linux/pci.h>
+
+#define DART_MAX_STREAMS 16
+#define DART_MAX_TTBR 4
+
+#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(23, 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_STREAM_REMAP 0x80
+
+#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 @used_sids and hardware operations involving this dart
+ * @used_sids: bitmap of streams attached to a domain
+ * @pgsize: pagesize supported by this DART
+ * @supports_bypass: indicates if this DART supports bypass mode
+ * @force_bypass: force bypass mode due to pagesize mismatch?
+ * @sw_bypass_cpu_start: offset into cpu address space in software bypass mode
+ * @sw_bypass_dma_start: offset into dma address space in software bypass mode
+ * @sw_bypass_len: length of iova space in software bypass mode
+ * @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 used_sids;
+	u32 pgsize;
+
+	u32 supports_bypass : 1;
+	u32 force_bypass : 1;
+
+	u64 sw_bypass_cpu_start;
+	u64 sw_bypass_dma_start;
+	u64 sw_bypass_len;
+
+	struct iommu_device iommu;
+};
+
+/*
+ * This structure is used to identify a single stream attached to a domain.
+ * It's used as a list inside that domain to be able to attach multiple
+ * streams to a single domain. Since multiple devices can use a single stream
+ * it additionally keeps track of how many devices are represented by this
+ * stream. Once that number reaches zero it is detached from the IOMMU domain
+ * and all translations from this stream are disabled.
+ *
+ * @dart: DART instance to which this stream belongs
+ * @sid: stream id within the DART instance
+ * @num_devices: count of devices attached to this stream
+ * @stream_head: list head for the next stream
+ */
+struct apple_dart_stream {
+	struct apple_dart *dart;
+	u32 sid;
+
+	u32 num_devices;
+
+	struct list_head stream_head;
+};
+
+/*
+ * This structure is attached to each iommu domain handled by a DART.
+ * A single domain is used to represent a single virtual address space.
+ * It is always allocated together with a page table.
+ *
+ * Streams are the smallest units the DART hardware can differentiate.
+ * These are pointed to the page table of a domain whenever a device is
+ * attached to it. A single stream can only be assigned to a single domain.
+ *
+ * Devices are assigned to at least a single and sometimes multiple individual
+ * streams (using the iommus property in the device tree). Multiple devices
+ * can theoretically be represented by the same stream, though this is usually
+ * not the case.
+ *
+ * We only keep track of streams here and just count how many devices are
+ * represented by each stream. When the last device is removed the whole stream
+ * is removed from the domain.
+ *
+ * @dart: pointer to the DART instance
+ * @pgtbl_ops: pagetable ops allocated by io-pgtable
+ * @type: domain type IOMMU_DOMAIN_IDENTITY_{IDENTITY,DMA,UNMANAGED,BLOCKED}
+ * @sw_bypass_cpu_start: offset into cpu address space in software bypass mode
+ * @sw_bypass_dma_start: offset into dma address space in software bypass mode
+ * @sw_bypass_len: length of iova space in software bypass mode
+ * @streams: list of streams attached to this domain
+ * @lock: spinlock for operations involving the list of streams
+ * @domain: core iommu domain pointer
+ */
+struct apple_dart_domain {
+	struct apple_dart *dart;
+	struct io_pgtable_ops *pgtbl_ops;
+
+	unsigned int type;
+
+	u64 sw_bypass_cpu_start;
+	u64 sw_bypass_dma_start;
+	u64 sw_bypass_len;
+
+	struct list_head streams;
+
+	spinlock_t lock;
+
+	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 as defined in the
+ * device tree. Multiple DART instances can be attached to a single device
+ * and each stream is identified by its stream id.
+ * It's usually reference by a pointer called *cfg.
+ *
+ * A dynamic array instead of a linked list is used here since in almost
+ * all cases a device will just be attached to a single stream and streams
+ * are never removed after they have been added.
+ *
+ * @num_streams: number of streams attached
+ * @streams: array of structs to identify attached streams and the device link
+ *           to the iommu
+ */
+struct apple_dart_master_cfg {
+	int num_streams;
+	struct {
+		struct apple_dart *dart;
+		u32 sid;
+
+		struct device_link *link;
+	} streams[];
+};
+
+static struct platform_driver apple_dart_driver;
+static const struct iommu_ops apple_dart_iommu_ops;
+static const struct iommu_flush_ops apple_dart_tlb_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 *dart, u16 sid)
+{
+	writel(DART_TCR_TRANSLATE_ENABLE, dart->regs + DART_TCR(sid));
+}
+
+static void apple_dart_hw_disable_dma(struct apple_dart *dart, u16 sid)
+{
+	writel(0, dart->regs + DART_TCR(sid));
+}
+
+static void apple_dart_hw_enable_bypass(struct apple_dart *dart, u16 sid)
+{
+	WARN_ON(!dart->supports_bypass);
+	writel(DART_TCR_BYPASS0_ENABLE | DART_TCR_BYPASS1_ENABLE,
+	       dart->regs + DART_TCR(sid));
+}
+
+static void apple_dart_hw_set_ttbr(struct apple_dart *dart, u16 sid, u16 idx,
+				   phys_addr_t paddr)
+{
+	writel(DART_TTBR_VALID | (paddr >> DART_TTBR_SHIFT),
+	       dart->regs + DART_TTBR(sid, idx));
+}
+
+static void apple_dart_hw_clear_ttbr(struct apple_dart *dart, u16 sid, u16 idx)
+{
+	writel(0, dart->regs + DART_TTBR(sid, idx));
+}
+
+static void apple_dart_hw_clear_all_ttbrs(struct apple_dart *dart, u16 sid)
+{
+	int i;
+
+	for (i = 0; i < 4; ++i)
+		apple_dart_hw_clear_ttbr(dart, sid, i);
+}
+
+static int apple_dart_hw_stream_command(struct apple_dart *dart, u16 sid_bitmap,
+					u32 command)
+{
+	unsigned long flags;
+	int ret;
+	u32 command_reg;
+
+	spin_lock_irqsave(&dart->lock, flags);
+
+	writel(sid_bitmap, dart->regs + DART_STREAM_SELECT);
+	writel(command, dart->regs + DART_STREAM_COMMAND);
+
+	ret = readl_poll_timeout_atomic(
+		dart->regs + DART_STREAM_COMMAND, command_reg,
+		!(command_reg & DART_STREAM_COMMAND_BUSY), 1,
+		DART_STREAM_COMMAND_BUSY_TIMEOUT);
+
+	spin_unlock_irqrestore(&dart->lock, flags);
+
+	if (ret) {
+		dev_err(dart->dev,
+			"busy bit did not clear after command %x for streams %x\n",
+			command, sid_bitmap);
+		return ret;
+	}
+
+	return 0;
+}
+
+static int apple_dart_hw_invalidate_tlb_global(struct apple_dart *dart)
+{
+	return apple_dart_hw_stream_command(dart, DART_STREAM_ALL,
+					    DART_STREAM_COMMAND_INVALIDATE);
+}
+
+static int apple_dart_hw_invalidate_tlb_stream(struct apple_dart *dart, u16 sid)
+{
+	return apple_dart_hw_stream_command(dart, 1 << sid,
+					    DART_STREAM_COMMAND_INVALIDATE);
+}
+
+static int apple_dart_hw_reset(struct apple_dart *dart)
+{
+	int sid;
+	u32 config;
+
+	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;
+	}
+
+	for (sid = 0; sid < DART_MAX_STREAMS; ++sid) {
+		apple_dart_hw_disable_dma(dart, sid);
+		apple_dart_hw_clear_all_ttbrs(dart, sid);
+	}
+
+	/* restore stream identity map */
+	writel(0x03020100, dart->regs + DART_STREAM_REMAP);
+	writel(0x07060504, dart->regs + DART_STREAM_REMAP + 4);
+	writel(0x0b0a0908, dart->regs + DART_STREAM_REMAP + 8);
+	writel(0x0f0e0d0c, dart->regs + DART_STREAM_REMAP + 12);
+
+	/* 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_global(dart);
+}
+
+static void apple_dart_domain_flush_tlb(struct apple_dart_domain *domain)
+{
+	unsigned long flags;
+	struct apple_dart_stream *stream;
+	struct apple_dart *dart = domain->dart;
+
+	if (!dart)
+		return;
+
+	spin_lock_irqsave(&domain->lock, flags);
+	list_for_each_entry(stream, &domain->streams, stream_head) {
+		apple_dart_hw_invalidate_tlb_stream(stream->dart, stream->sid);
+	}
+	spin_unlock_irqrestore(&domain->lock, flags);
+}
+
+static void apple_dart_flush_iotlb_all(struct iommu_domain *domain)
+{
+	struct apple_dart_domain *dart_domain = to_dart_domain(domain);
+
+	apple_dart_domain_flush_tlb(dart_domain);
+}
+
+static void apple_dart_iotlb_sync(struct iommu_domain *domain,
+				  struct iommu_iotlb_gather *gather)
+{
+	struct apple_dart_domain *dart_domain = to_dart_domain(domain);
+
+	apple_dart_domain_flush_tlb(dart_domain);
+}
+
+static void apple_dart_iotlb_sync_map(struct iommu_domain *domain,
+				      unsigned long iova, size_t size)
+{
+	struct apple_dart_domain *dart_domain = to_dart_domain(domain);
+
+	apple_dart_domain_flush_tlb(dart_domain);
+}
+
+static void apple_dart_tlb_flush_all(void *cookie)
+{
+	struct apple_dart_domain *domain = cookie;
+
+	apple_dart_domain_flush_tlb(domain);
+}
+
+static void apple_dart_tlb_flush_walk(unsigned long iova, size_t size,
+				      size_t granule, void *cookie)
+{
+	struct apple_dart_domain *domain = cookie;
+
+	apple_dart_domain_flush_tlb(domain);
+}
+
+static const struct iommu_flush_ops apple_dart_tlb_ops = {
+	.tlb_flush_all = apple_dart_tlb_flush_all,
+	.tlb_flush_walk = apple_dart_tlb_flush_walk,
+	.tlb_add_page = NULL,
+};
+
+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 (domain->type == IOMMU_DOMAIN_IDENTITY &&
+	    dart_domain->dart->supports_bypass)
+		return iova;
+	if (!ops)
+		return -ENODEV;
+
+	return ops->iova_to_phys(ops, iova);
+}
+
+static int apple_dart_map(struct iommu_domain *domain, unsigned long iova,
+			  phys_addr_t paddr, size_t size, int prot, gfp_t gfp)
+{
+	struct apple_dart_domain *dart_domain = to_dart_domain(domain);
+	struct io_pgtable_ops *ops = dart_domain->pgtbl_ops;
+
+	if (!ops)
+		return -ENODEV;
+	if (prot & IOMMU_MMIO)
+		return -EINVAL;
+	if (prot & IOMMU_NOEXEC)
+		return -EINVAL;
+
+	return ops->map(ops, iova, paddr, size, prot, gfp);
+}
+
+static size_t apple_dart_unmap(struct iommu_domain *domain, unsigned long iova,
+			       size_t size, struct iommu_iotlb_gather *gather)
+{
+	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->unmap(ops, iova, size, gather);
+}
+
+static int apple_dart_prepare_sw_bypass(struct apple_dart *dart,
+					struct apple_dart_domain *dart_domain,
+					struct device *dev)
+{
+	lockdep_assert_held(&dart_domain->lock);
+
+	if (dart->supports_bypass)
+		return 0;
+	if (dart_domain->type != IOMMU_DOMAIN_IDENTITY)
+		return 0;
+
+	// use the bus region from the first attached dev for the bypass range
+	if (!dart->sw_bypass_len) {
+		const struct bus_dma_region *dma_rgn = dev->dma_range_map;
+
+		if (!dma_rgn)
+			return -EINVAL;
+
+		dart->sw_bypass_len = dma_rgn->size;
+		dart->sw_bypass_cpu_start = dma_rgn->cpu_start;
+		dart->sw_bypass_dma_start = dma_rgn->dma_start;
+	}
+
+	// ensure that we don't mix different bypass setups
+	if (dart_domain->sw_bypass_len) {
+		if (dart->sw_bypass_len != dart_domain->sw_bypass_len)
+			return -EINVAL;
+		if (dart->sw_bypass_cpu_start !=
+		    dart_domain->sw_bypass_cpu_start)
+			return -EINVAL;
+		if (dart->sw_bypass_dma_start !=
+		    dart_domain->sw_bypass_dma_start)
+			return -EINVAL;
+	} else {
+		dart_domain->sw_bypass_len = dart->sw_bypass_len;
+		dart_domain->sw_bypass_cpu_start = dart->sw_bypass_cpu_start;
+		dart_domain->sw_bypass_dma_start = dart->sw_bypass_dma_start;
+	}
+
+	return 0;
+}
+
+static int apple_dart_domain_needs_pgtbl_ops(struct apple_dart *dart,
+					     struct iommu_domain *domain)
+{
+	if (domain->type == IOMMU_DOMAIN_DMA)
+		return 1;
+	if (domain->type == IOMMU_DOMAIN_UNMANAGED)
+		return 1;
+	if (!dart->supports_bypass && domain->type == IOMMU_DOMAIN_IDENTITY)
+		return 1;
+	return 0;
+}
+
+static int apple_dart_finalize_domain(struct iommu_domain *domain)
+{
+	struct apple_dart_domain *dart_domain = to_dart_domain(domain);
+	struct apple_dart *dart = dart_domain->dart;
+	struct io_pgtable_cfg pgtbl_cfg;
+
+	lockdep_assert_held(&dart_domain->lock);
+
+	if (dart_domain->pgtbl_ops)
+		return 0;
+	if (!apple_dart_domain_needs_pgtbl_ops(dart, domain))
+		return 0;
+
+	pgtbl_cfg = (struct io_pgtable_cfg){
+		.pgsize_bitmap = dart->pgsize,
+		.ias = 32,
+		.oas = 36,
+		.coherent_walk = 1,
+		.tlb = &apple_dart_tlb_ops,
+		.iommu_dev = dart->dev,
+	};
+
+	dart_domain->pgtbl_ops =
+		alloc_io_pgtable_ops(ARM_APPLE_DART, &pgtbl_cfg, domain);
+	if (!dart_domain->pgtbl_ops)
+		return -ENOMEM;
+
+	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;
+
+	/*
+	 * Some DARTs come without hardware bypass support but we may still
+	 * be forced to use bypass mode (to e.g. allow kernels with 4K pages to
+	 * boot). If we reach this point with an identity domain we have to setup
+	 * bypass mode in software. This is done by creating a static pagetable
+	 * for a linear map specified by dma-ranges in the device tree.
+	 */
+	if (domain->type == IOMMU_DOMAIN_IDENTITY) {
+		u64 offset;
+		int ret;
+
+		for (offset = 0; offset < dart_domain->sw_bypass_len;
+		     offset += dart->pgsize) {
+			ret = dart_domain->pgtbl_ops->map(
+				dart_domain->pgtbl_ops,
+				dart_domain->sw_bypass_dma_start + offset,
+				dart_domain->sw_bypass_cpu_start + offset,
+				dart->pgsize, IOMMU_READ | IOMMU_WRITE,
+				GFP_ATOMIC);
+			if (ret < 0) {
+				free_io_pgtable_ops(dart_domain->pgtbl_ops);
+				dart_domain->pgtbl_ops = NULL;
+				return -EINVAL;
+			}
+		}
+	}
+
+	return 0;
+}
+
+static void
+apple_dart_stream_setup_translation(struct apple_dart_domain *domain,
+				    struct apple_dart *dart, u32 sid)
+{
+	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(dart, sid, i,
+				       pgtbl_cfg->apple_dart_cfg.ttbr[i]);
+	for (; i < DART_MAX_TTBR; ++i)
+		apple_dart_hw_clear_ttbr(dart, sid, i);
+
+	apple_dart_hw_enable_translation(dart, sid);
+	apple_dart_hw_invalidate_tlb_stream(dart, sid);
+}
+
+static int apple_dart_attach_stream(struct apple_dart_domain *domain,
+				    struct apple_dart *dart, u32 sid)
+{
+	unsigned long flags;
+	struct apple_dart_stream *stream;
+	int ret;
+
+	lockdep_assert_held(&domain->lock);
+
+	if (WARN_ON(dart->force_bypass &&
+		    domain->type != IOMMU_DOMAIN_IDENTITY))
+		return -EINVAL;
+
+	/*
+	 * we can't mix and match DARTs that support bypass mode with those who don't
+	 * because the iova space in fake bypass mode generally has an offset
+	 */
+	if (WARN_ON(domain->type == IOMMU_DOMAIN_IDENTITY &&
+		    (domain->dart->supports_bypass != dart->supports_bypass)))
+		return -EINVAL;
+
+	list_for_each_entry(stream, &domain->streams, stream_head) {
+		if (stream->dart == dart && stream->sid == sid) {
+			stream->num_devices++;
+			return 0;
+		}
+	}
+
+	spin_lock_irqsave(&dart->lock, flags);
+
+	if (WARN_ON(dart->used_sids & BIT(sid))) {
+		ret = -EINVAL;
+		goto error;
+	}
+
+	stream = kzalloc(sizeof(*stream), GFP_ATOMIC);
+	if (!stream) {
+		ret = -ENOMEM;
+		goto error;
+	}
+
+	stream->dart = dart;
+	stream->sid = sid;
+	stream->num_devices = 1;
+	list_add(&stream->stream_head, &domain->streams);
+
+	dart->used_sids |= BIT(sid);
+	spin_unlock_irqrestore(&dart->lock, flags);
+
+	apple_dart_hw_clear_all_ttbrs(stream->dart, stream->sid);
+
+	switch (domain->type) {
+	case IOMMU_DOMAIN_IDENTITY:
+		if (stream->dart->supports_bypass)
+			apple_dart_hw_enable_bypass(stream->dart, stream->sid);
+		else
+			apple_dart_stream_setup_translation(
+				domain, stream->dart, stream->sid);
+		break;
+	case IOMMU_DOMAIN_BLOCKED:
+		apple_dart_hw_disable_dma(stream->dart, stream->sid);
+		break;
+	case IOMMU_DOMAIN_UNMANAGED:
+	case IOMMU_DOMAIN_DMA:
+		apple_dart_stream_setup_translation(domain, stream->dart,
+						    stream->sid);
+		break;
+	}
+
+	return 0;
+
+error:
+	spin_unlock_irqrestore(&dart->lock, flags);
+	return ret;
+}
+
+static void apple_dart_disable_stream(struct apple_dart *dart, u32 sid)
+{
+	unsigned long flags;
+
+	apple_dart_hw_disable_dma(dart, sid);
+	apple_dart_hw_clear_all_ttbrs(dart, sid);
+	apple_dart_hw_invalidate_tlb_stream(dart, sid);
+
+	spin_lock_irqsave(&dart->lock, flags);
+	dart->used_sids &= ~BIT(sid);
+	spin_unlock_irqrestore(&dart->lock, flags);
+}
+
+static void apple_dart_detach_stream(struct apple_dart_domain *domain,
+				     struct apple_dart *dart, u32 sid)
+{
+	struct apple_dart_stream *stream;
+
+	lockdep_assert_held(&domain->lock);
+
+	list_for_each_entry(stream, &domain->streams, stream_head) {
+		if (stream->dart == dart && stream->sid == sid) {
+			stream->num_devices--;
+
+			if (stream->num_devices == 0) {
+				apple_dart_disable_stream(dart, sid);
+				list_del(&stream->stream_head);
+				kfree(stream);
+			}
+			return;
+		}
+	}
+}
+
+static int apple_dart_attach_dev(struct iommu_domain *domain,
+				 struct device *dev)
+{
+	int ret;
+	int i, j;
+	unsigned long flags;
+	struct apple_dart_master_cfg *cfg = dev_iommu_priv_get(dev);
+	struct apple_dart_domain *dart_domain = to_dart_domain(domain);
+	struct apple_dart *dart = cfg->streams[0].dart;
+
+	if (WARN_ON(dart->force_bypass &&
+		    dart_domain->type != IOMMU_DOMAIN_IDENTITY)) {
+		dev_warn(
+			dev,
+			"IOMMU must be in bypass mode but trying to attach to translated domain.\n");
+		return -EINVAL;
+	}
+
+	spin_lock_irqsave(&dart_domain->lock, flags);
+
+	ret = apple_dart_prepare_sw_bypass(dart, dart_domain, dev);
+	if (ret)
+		goto out;
+
+	if (!dart_domain->dart)
+		dart_domain->dart = dart;
+
+	ret = apple_dart_finalize_domain(domain);
+	if (ret)
+		goto out;
+
+	for (i = 0; i < cfg->num_streams; ++i) {
+		ret = apple_dart_attach_stream(
+			dart_domain, cfg->streams[i].dart, cfg->streams[i].sid);
+		if (ret) {
+			/* try to undo what we did before returning */
+			for (j = 0; j < i; ++j)
+				apple_dart_detach_stream(dart_domain,
+							 cfg->streams[j].dart,
+							 cfg->streams[j].sid);
+
+			goto out;
+		}
+	}
+
+	ret = 0;
+
+out:
+	spin_unlock_irqrestore(&dart_domain->lock, flags);
+	return ret;
+}
+
+static void apple_dart_detach_dev(struct iommu_domain *domain,
+				  struct device *dev)
+{
+	int i;
+	unsigned long flags;
+	struct apple_dart_master_cfg *cfg = dev_iommu_priv_get(dev);
+	struct apple_dart_domain *dart_domain = to_dart_domain(domain);
+
+	spin_lock_irqsave(&dart_domain->lock, flags);
+
+	for (i = 0; i < cfg->num_streams; ++i)
+		apple_dart_detach_stream(dart_domain, cfg->streams[i].dart,
+					 cfg->streams[i].sid);
+
+	spin_unlock_irqrestore(&dart_domain->lock, flags);
+}
+
+static struct iommu_device *apple_dart_probe_device(struct device *dev)
+{
+	struct apple_dart_master_cfg *cfg = dev_iommu_priv_get(dev);
+	int i;
+
+	if (!cfg)
+		return ERR_PTR(-ENODEV);
+
+	for (i = 0; i < cfg->num_streams; ++i) {
+		cfg->streams[i].link =
+			device_link_add(dev, cfg->streams[i].dart->dev,
+					DL_FLAG_PM_RUNTIME | DL_FLAG_STATELESS);
+	}
+
+	return &cfg->streams[0].dart->iommu;
+}
+
+static void apple_dart_release_device(struct device *dev)
+{
+	struct apple_dart_master_cfg *cfg = dev_iommu_priv_get(dev);
+	int i;
+
+	if (!cfg)
+		return;
+
+	for (i = 0; i < cfg->num_streams; ++i)
+		device_link_del(cfg->streams[i].link);
+
+	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;
+
+	INIT_LIST_HEAD(&dart_domain->streams);
+	spin_lock_init(&dart_domain->lock);
+	iommu_get_dma_cookie(&dart_domain->domain);
+	dart_domain->type = type;
+
+	return &dart_domain->domain;
+}
+
+static void apple_dart_domain_free(struct iommu_domain *domain)
+{
+	struct apple_dart_domain *dart_domain = to_dart_domain(domain);
+
+	WARN_ON(!list_empty(&dart_domain->streams));
+
+	kfree(dart_domain);
+}
+
+static int apple_dart_of_xlate(struct device *dev, struct of_phandle_args *args)
+{
+	struct platform_device *iommu_pdev = of_find_device_by_node(args->np);
+	struct apple_dart_master_cfg *cfg = dev_iommu_priv_get(dev);
+	unsigned int num_streams = cfg ? cfg->num_streams : 0;
+	struct apple_dart_master_cfg *cfg_new;
+	struct apple_dart *dart = platform_get_drvdata(iommu_pdev);
+
+	if (args->args_count != 1)
+		return -EINVAL;
+
+	cfg_new = krealloc(cfg, struct_size(cfg, streams, num_streams + 1),
+			   GFP_KERNEL);
+	if (!cfg_new)
+		return -ENOMEM;
+
+	cfg = cfg_new;
+	dev_iommu_priv_set(dev, cfg);
+
+	cfg->num_streams = num_streams;
+	cfg->streams[cfg->num_streams].dart = dart;
+	cfg->streams[cfg->num_streams].sid = args->args[0];
+	cfg->num_streams++;
+
+	return 0;
+}
+
+static struct iommu_group *apple_dart_device_group(struct device *dev)
+{
+#ifdef CONFIG_PCI
+	struct iommu_group *group;
+
+	if (dev_is_pci(dev))
+		group = pci_device_group(dev);
+	else
+		group = generic_device_group(dev);
+
+	return group;
+#else
+	return generic_device_group(dev);
+#endif
+}
+
+static int apple_dart_def_domain_type(struct device *dev)
+{
+	struct apple_dart_master_cfg *cfg = dev_iommu_priv_get(dev);
+	struct apple_dart *dart = cfg->streams[0].dart;
+
+	if (dart->force_bypass)
+		return IOMMU_DOMAIN_IDENTITY;
+	if (!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 = apple_dart_map,
+	.unmap = apple_dart_unmap,
+	.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;
+	static DEFINE_RATELIMIT_STATE(rs, DEFAULT_RATELIMIT_INTERVAL,
+				      DEFAULT_RATELIMIT_BURST);
+	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;
+
+	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";
+
+	if (WARN_ON(fault_name == NULL))
+		fault_name = "unknown";
+
+	if (__ratelimit(&rs)) {
+		dev_err(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_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);
+
+	if (pdev->num_resources < 1)
+		return -ENODEV;
+
+	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);
+
+	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;
+
+	dart->irq = platform_get_irq(pdev, 0);
+	if (dart->irq < 0) {
+		ret = -ENODEV;
+		goto err_clk_disable;
+	}
+
+	ret = devm_request_irq(dart->dev, dart->irq, apple_dart_irq,
+			       IRQF_SHARED, "apple-dart fault handler", dart);
+	if (ret)
+		goto err_clk_disable;
+
+	platform_set_drvdata(pdev, dart);
+
+	ret = iommu_device_sysfs_add(&dart->iommu, dev, NULL, "apple-dart.%s",
+				     dev_name(&pdev->dev));
+	if (ret)
+		goto err_clk_disable;
+
+	ret = iommu_device_register(&dart->iommu, &apple_dart_iommu_ops, dev);
+	if (ret)
+		goto err_clk_disable;
+
+	if (dev->bus->iommu_ops != &apple_dart_iommu_ops) {
+		ret = bus_set_iommu(dev->bus, &apple_dart_iommu_ops);
+		if (ret)
+			goto err_clk_disable;
+	}
+#ifdef CONFIG_PCI
+	if (dev->bus->iommu_ops != pci_bus_type.iommu_ops) {
+		ret = bus_set_iommu(&pci_bus_type, &apple_dart_iommu_ops);
+		if (ret)
+			goto err_clk_disable;
+	}
+#endif
+
+	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_clk_disable:
+	clk_bulk_disable(dart->num_clks, dart->clks);
+	clk_bulk_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);
+
+	devm_free_irq(dart->dev, dart->irq, dart);
+
+	iommu_device_unregister(&dart->iommu);
+	iommu_device_sysfs_remove(&dart->iommu);
+
+	clk_bulk_disable(dart->num_clks, dart->clks);
+	clk_bulk_unprepare(dart->num_clks, dart->clks);
+
+	return 0;
+}
+
+static void apple_dart_shutdown(struct platform_device *pdev)
+{
+	apple_dart_remove(pdev);
+}
+
+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,
+	},
+	.probe	= apple_dart_probe,
+	.remove	= apple_dart_remove,
+	.shutdown = apple_dart_shutdown,
+};
+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");
-- 
2.25.1