[PATCH v3 0/3] Apple M1 DART IOMMU driver

[PATCH v3 0/3] Apple M1 DART IOMMU driver

[Sven Peter]

Hi,

This is v3 of my Apple M1 DART IOMMU driver series as a follow up to the original
two versions [1][2].

Short summary: this series adds support for the iommu found in Apple's new M1
SoC which is required to use DMA on most peripherals. So far this code has been
tested with dwc3 in host and device mode and PCIe on a M1 Mac Mini.

This IOMMU comes with a hard-wired pagesize of 16K. This makes booting a
kernel with 4K page challenging.

For dwc3 this is no issue: As long as the iommu is set to bypass mode
dwc3 works just fine. Translated mode isn't supported right now.

The most controversial part on which I'd like to get feedback are the
PCIe DARTs. These DARTs do not support hardware bypass mode and also limit
the iova space to 32 bit. To still allow booting on kernels with a 4K
pagesize I have introduced the following hack:

I program a static pagetable that maps the entire 32bit iova space to the
first 4GB of RAM starting at 0x8_0000_0000. Combined with an appropriate
dma-ranges property in the pcie node this allows to create a fake
bypass mode and successfully enables PCIe.
Right now the RAM offset is hardcoded in the DART driver and this will
likely have to change if this workaround is acceptable for now. I could
either introduce a separate property for the iommu node or try to grab
the offset from the dma-ranges once the first device is attached.


Changes for v3:
 - fixed name of the iommu node in the device tree binding example
   pointed out by Arnd Bergmann
 - remove hardware specific checks from io-pgtable.c  as pointed out by
   Will Deacon
 - introduced a fake bypass mode by programming static linear pagetables
   if the DART does not support regular bypass mode as proposed by Alex
   Graf
 - added checks to enforce bypass mode if there is a pagesize mismatch
   between the DART HW and the CPU.
 - fixed usage of GFP_KERNEL during a held spinlock found by Julia Lawall
 - rebased on v5.13-rc3

Changes for v2:
 - fixed devicetree binding linting issues pointed out by Rob Herring and
   reworked that file.
 - made DART-specific code in io-pgtable.c unconditional and removed flag from
   Kconfig as proposed by Robin Murphy.
 - allowed multiple DART nodes in the "iommus" property as proposed by
   Rob Herring and Robin Murphy. this resulted in significant changes
   to apple-iommu-dart.c.
 - the domain aperture is now forced to 32bit if translation is enabled after
   the original suggestion to limit the aperture by Mark Kettenis and the
   follow-up discussion and investigation with Mark Kettenis, Arnd Bergmann,
   Robin Murphy and Rob Herring. This change also simplified the code
   in io-pgtable.c and made some of the improvements suggested during review
   not apply anymore.
 - added support for bypassed and isolated domain modes.
 - reject IOMMU_MMIO and IOMMU_NOEXEC since it's unknown how to set these up
   for now or if the hardware even supports these flags.
 - renamed some registers to be less confusing (mainly s/DOMAIN/STREAM/ to
   prevent confusion with linux's iommu domain concept).


[1] v1: https://lore.kernel.org/linux-iommu/20210320151903.60759-1-sven@svenpeter.dev/
[2] v2: https://lore.kernel.org/linux-iommu/20210328074009.95932-1-sven@svenpeter.dev/

Sven Peter (3):
  iommu: io-pgtable: add DART pagetable format
  dt-bindings: iommu: add DART iommu bindings
  iommu: dart: Add DART iommu driver

 .../devicetree/bindings/iommu/apple,dart.yaml |  81 ++
 MAINTAINERS                                   |   7 +
 drivers/iommu/Kconfig                         |  15 +
 drivers/iommu/Makefile                        |   1 +
 drivers/iommu/apple-dart-iommu.c              | 966 ++++++++++++++++++
 drivers/iommu/io-pgtable-arm.c                |  62 ++
 drivers/iommu/io-pgtable.c                    |   1 +
 include/linux/io-pgtable.h                    |   7 +
 8 files changed, 1140 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iommu/apple,dart.yaml
 create mode 100644 drivers/iommu/apple-dart-iommu.c

-- 
2.25.1


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[PATCH v3 1/3] iommu: io-pgtable: add DART pagetable format

[Sven Peter]

Apple's DART iommu uses a pagetable format that shares some
similarities with the ones already implemented by io-pgtable.c.
Add a new format variant to support the required differences
so that we don't have to duplicate the pagetable handling code.

Signed-off-by: Sven Peter <sven@svenpeter.dev>
---
 drivers/iommu/io-pgtable-arm.c | 62 ++++++++++++++++++++++++++++++++++
 drivers/iommu/io-pgtable.c     |  1 +
 include/linux/io-pgtable.h     |  7 ++++
 3 files changed, 70 insertions(+)

diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
index 87def58e79b5..1dd5c45b4b5b 100644
--- a/drivers/iommu/io-pgtable-arm.c
+++ b/drivers/iommu/io-pgtable-arm.c
@@ -127,6 +127,9 @@
 #define ARM_MALI_LPAE_MEMATTR_IMP_DEF	0x88ULL
 #define ARM_MALI_LPAE_MEMATTR_WRITE_ALLOC 0x8DULL
 
+#define APPLE_DART_PTE_PROT_NO_WRITE (1<<7)
+#define APPLE_DART_PTE_PROT_NO_READ (1<<8)
+
 /* IOPTE accessors */
 #define iopte_deref(pte,d) __va(iopte_to_paddr(pte, d))
 
@@ -381,6 +384,15 @@ static arm_lpae_iopte arm_lpae_prot_to_pte(struct arm_lpae_io_pgtable *data,
 {
 	arm_lpae_iopte pte;
 
+	if (data->iop.fmt == ARM_APPLE_DART) {
+		pte = 0;
+		if (!(prot & IOMMU_WRITE))
+			pte |= APPLE_DART_PTE_PROT_NO_WRITE;
+		if (!(prot & IOMMU_READ))
+			pte |= APPLE_DART_PTE_PROT_NO_READ;
+		return pte;
+	}
+
 	if (data->iop.fmt == ARM_64_LPAE_S1 ||
 	    data->iop.fmt == ARM_32_LPAE_S1) {
 		pte = ARM_LPAE_PTE_nG;
@@ -1043,6 +1055,51 @@ arm_mali_lpae_alloc_pgtable(struct io_pgtable_cfg *cfg, void *cookie)
 	return NULL;
 }
 
+static struct io_pgtable *
+apple_dart_alloc_pgtable(struct io_pgtable_cfg *cfg, void *cookie)
+{
+	struct arm_lpae_io_pgtable *data;
+	int i;
+
+	if (cfg->oas > 36)
+		return NULL;
+
+	data = arm_lpae_alloc_pgtable(cfg);
+	if (!data)
+		return NULL;
+
+	/*
+	 * Apple's DART always requires three levels with the first level being
+	 * stored in four MMIO registers. We always concatenate the first and
+	 * second level so that we only have to setup the MMIO registers once.
+	 * This results in an effective two level pagetable.
+	 */
+	if (data->start_level < 1)
+		return NULL;
+	if (data->start_level == 1 && data->pgd_bits > 2)
+		return NULL;
+	if (data->start_level > 1)
+		data->pgd_bits = 0;
+	data->start_level = 2;
+	cfg->apple_dart_cfg.n_ttbrs = 1 << data->pgd_bits;
+	data->pgd_bits += data->bits_per_level;
+
+	data->pgd = __arm_lpae_alloc_pages(ARM_LPAE_PGD_SIZE(data), GFP_KERNEL,
+					   cfg);
+	if (!data->pgd)
+		goto out_free_data;
+
+	for (i = 0; i < cfg->apple_dart_cfg.n_ttbrs; ++i)
+		cfg->apple_dart_cfg.ttbr[i] =
+			virt_to_phys(data->pgd + i * ARM_LPAE_GRANULE(data));
+
+	return &data->iop;
+
+out_free_data:
+	kfree(data);
+	return NULL;
+}
+
 struct io_pgtable_init_fns io_pgtable_arm_64_lpae_s1_init_fns = {
 	.alloc	= arm_64_lpae_alloc_pgtable_s1,
 	.free	= arm_lpae_free_pgtable,
@@ -1068,6 +1125,11 @@ struct io_pgtable_init_fns io_pgtable_arm_mali_lpae_init_fns = {
 	.free	= arm_lpae_free_pgtable,
 };
 
+struct io_pgtable_init_fns io_pgtable_apple_dart_init_fns = {
+	.alloc	= apple_dart_alloc_pgtable,
+	.free	= arm_lpae_free_pgtable,
+};
+
 #ifdef CONFIG_IOMMU_IO_PGTABLE_LPAE_SELFTEST
 
 static struct io_pgtable_cfg *cfg_cookie __initdata;
diff --git a/drivers/iommu/io-pgtable.c b/drivers/iommu/io-pgtable.c
index 6e9917ce980f..fd8e6bd6caf9 100644
--- a/drivers/iommu/io-pgtable.c
+++ b/drivers/iommu/io-pgtable.c
@@ -20,6 +20,7 @@ io_pgtable_init_table[IO_PGTABLE_NUM_FMTS] = {
 	[ARM_64_LPAE_S1] = &io_pgtable_arm_64_lpae_s1_init_fns,
 	[ARM_64_LPAE_S2] = &io_pgtable_arm_64_lpae_s2_init_fns,
 	[ARM_MALI_LPAE] = &io_pgtable_arm_mali_lpae_init_fns,
+	[ARM_APPLE_DART] = &io_pgtable_apple_dart_init_fns,
 #endif
 #ifdef CONFIG_IOMMU_IO_PGTABLE_ARMV7S
 	[ARM_V7S] = &io_pgtable_arm_v7s_init_fns,
diff --git a/include/linux/io-pgtable.h b/include/linux/io-pgtable.h
index 4d40dfa75b55..a4bfac7f85f7 100644
--- a/include/linux/io-pgtable.h
+++ b/include/linux/io-pgtable.h
@@ -16,6 +16,7 @@ enum io_pgtable_fmt {
 	ARM_V7S,
 	ARM_MALI_LPAE,
 	AMD_IOMMU_V1,
+	ARM_APPLE_DART,
 	IO_PGTABLE_NUM_FMTS,
 };
 
@@ -136,6 +137,11 @@ struct io_pgtable_cfg {
 			u64	transtab;
 			u64	memattr;
 		} arm_mali_lpae_cfg;
+
+		struct {
+			u64 ttbr[4];
+			u32 n_ttbrs;
+		} apple_dart_cfg;
 	};
 };
 
@@ -246,5 +252,6 @@ extern struct io_pgtable_init_fns io_pgtable_arm_64_lpae_s2_init_fns;
 extern struct io_pgtable_init_fns io_pgtable_arm_v7s_init_fns;
 extern struct io_pgtable_init_fns io_pgtable_arm_mali_lpae_init_fns;
 extern struct io_pgtable_init_fns io_pgtable_amd_iommu_v1_init_fns;
+extern struct io_pgtable_init_fns io_pgtable_apple_dart_init_fns;
 
 #endif /* __IO_PGTABLE_H */
-- 
2.25.1


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[PATCH v3 2/3] dt-bindings: iommu: add DART iommu bindings

[Sven Peter]

DART (Device Address Resolution Table) is the iommu found on Apple
ARM SoCs such as the M1.

Signed-off-by: Sven Peter <sven@svenpeter.dev>
---
 .../devicetree/bindings/iommu/apple,dart.yaml | 81 +++++++++++++++++++
 MAINTAINERS                                   |  6 ++
 2 files changed, 87 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iommu/apple,dart.yaml

diff --git a/Documentation/devicetree/bindings/iommu/apple,dart.yaml b/Documentation/devicetree/bindings/iommu/apple,dart.yaml
new file mode 100644
index 000000000000..db21ca07d121
--- /dev/null
+++ b/Documentation/devicetree/bindings/iommu/apple,dart.yaml
@@ -0,0 +1,81 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iommu/apple,dart.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Apple DART IOMMU
+
+maintainers:
+  - Sven Peter <sven@svenpeter.dev>
+
+description: |+
+  Apple SoCs may contain an implementation of their Device Address
+  Resolution Table which provides a mandatory layer of address
+  translations for various masters.
+
+  Each DART instance is capable of handling up to 16 different streams
+  with individual pagetables and page-level read/write protection flags.
+
+  This DART IOMMU also raises interrupts in response to various
+  fault conditions.
+
+properties:
+  compatible:
+    const: apple,t8103-dart
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  clocks:
+    description:
+      Reference to the gate clock phandle if required for this IOMMU.
+      Optional since not all IOMMUs are attached to a clock gate.
+
+  '#iommu-cells':
+    const: 1
+    description:
+      Has to be one. The single cell describes the stream id emitted by
+      a master to the IOMMU.
+
+required:
+  - compatible
+  - reg
+  - '#iommu-cells'
+  - interrupts
+
+additionalProperties: false
+
+examples:
+  - |+
+    dart1: iommu@82f80000 {
+      compatible = "apple,t8103-dart";
+      reg = <0x82f80000 0x4000>;
+      interrupts = <1 781 4>;
+      #iommu-cells = <1>;
+    };
+
+    master1 {
+      iommus = <&{/dart1} 0>;
+    };
+
+  - |+
+    dart2a: iommu@82f00000 {
+      compatible = "apple,t8103-dart";
+      reg = <0x82f00000 0x4000>;
+      interrupts = <1 781 4>;
+      #iommu-cells = <1>;
+    };
+    dart2b: iommu@82f80000 {
+      compatible = "apple,t8103-dart";
+      reg = <0x82f80000 0x4000>;
+      interrupts = <1 781 4>;
+      #iommu-cells = <1>;
+    };
+
+    master2 {
+      iommus = <&{/dart2a} 0>, <&{/dart2b} 1>;
+    };
diff --git a/MAINTAINERS b/MAINTAINERS
index 673cadd5107a..4373d63f9ccf 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1240,6 +1240,12 @@ L:	linux-input@vger.kernel.org
 S:	Odd fixes
 F:	drivers/input/mouse/bcm5974.c
 
+APPLE DART IOMMU DRIVER
+M:	Sven Peter <sven@svenpeter.dev>
+L:	iommu@lists.linux-foundation.org
+S:	Maintained
+F:	Documentation/devicetree/bindings/iommu/apple,dart.yaml
+
 APPLE SMC DRIVER
 M:	Henrik Rydberg <rydberg@bitmath.org>
 L:	linux-hwmon@vger.kernel.org
-- 
2.25.1


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[PATCH v3 3/3] iommu: dart: Add DART iommu driver

[Sven Peter]

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 | 966 +++++++++++++++++++++++++++++++
 4 files changed, 983 insertions(+)
 create mode 100644 drivers/iommu/apple-dart-iommu.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 4373d63f9ccf..cb9200ad05fe 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..2777852498de
--- /dev/null
+++ b/drivers/iommu/apple-dart-iommu.c
@@ -0,0 +1,966 @@
+// 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-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/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?
+ * @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 force_bypass_offset;
+	u64 force_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 spaces.
+ * 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}
+ * @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;
+
+	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);
+		apple_dart_hw_enable_translation(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)
+		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_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;
+}
+
+/* must be called with held dart_domain->lock */
+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;
+
+	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;
+
+	// HACK: create a static pagetable to fake bypass mode
+	if (domain->type == IOMMU_DOMAIN_IDENTITY) {
+		u64 addr;
+
+		for (addr = 0; addr < dart->force_bypass_len;
+		     addr += dart->pgsize)
+			dart_domain->pgtbl_ops->map(
+				dart_domain->pgtbl_ops, addr,
+				dart->force_bypass_offset + addr, dart->pgsize,
+				IOMMU_READ | IOMMU_WRITE, GFP_ATOMIC);
+	}
+
+	return 0;
+}
+
+static void apple_dart_stream_setup_ttbrs(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);
+}
+
+/* must be called with held domain->lock */
+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;
+
+	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_ttbrs(domain, stream->dart,
+						      stream->sid);
+			apple_dart_hw_enable_translation(stream->dart,
+							 stream->sid);
+			apple_dart_hw_invalidate_tlb_stream(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_ttbrs(domain, stream->dart,
+					      stream->sid);
+		apple_dart_hw_enable_translation(stream->dart, stream->sid);
+		apple_dart_hw_invalidate_tlb_stream(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);
+}
+
+/* must be called with held domain->lock */
+static void apple_dart_detach_stream(struct apple_dart_domain *domain,
+				     struct apple_dart *dart, u32 sid)
+{
+	struct apple_dart_stream *stream;
+
+	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;
+
+	spin_lock_irqsave(&dart_domain->lock, flags);
+
+	if (!dart_domain->dart)
+		dart_domain->dart = 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");
+		ret = -EINVAL;
+		goto out;
+	}
+
+	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 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,
+	.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)
+		return ret;
+
+	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;
+
+	// HACK: these shouldn't be hardcoded here but come from the device tree
+	dart->force_bypass_offset = 0x0800000000;
+	dart->force_bypass_len = 0x0100000000;
+
+	dart->irq = platform_get_irq(pdev, 0);
+	if (dart->irq < 0)
+		return -ENODEV;
+
+	ret = devm_request_irq(dart->dev, dart->irq, apple_dart_irq,
+			       IRQF_SHARED, "apple-dart fault handler", dart);
+	if (ret)
+		return ret;
+
+	platform_set_drvdata(pdev, dart);
+
+	ret = iommu_device_sysfs_add(&dart->iommu, dev, NULL, "apple-dart.%s",
+				     dev_name(&pdev->dev));
+	if (ret)
+		return ret;
+
+	ret = iommu_device_register(&dart->iommu, &apple_dart_iommu_ops, dev);
+	if (ret)
+		return ret;
+
+	if (dev->bus->iommu_ops != &apple_dart_iommu_ops) {
+		ret = bus_set_iommu(dev->bus, &apple_dart_iommu_ops);
+		if (ret)
+			return ret;
+	}
+#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)
+			return ret;
+	}
+#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;
+}
+
+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


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Re: [PATCH v3 3/3] iommu: dart: Add DART iommu driver

[Rouven Czerwinski]

Hi Sven,

just a small comment, see inline.

On Thu, 2021-06-03 at 10:50 +0200, Sven Peter wrote:
> 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 | 966 +++++++++++++++++++++++++++++++
>  4 files changed, 983 insertions(+)
>  create mode 100644 drivers/iommu/apple-dart-iommu.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 4373d63f9ccf..cb9200ad05fe 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..2777852498de
> --- /dev/null
> +++ b/drivers/iommu/apple-dart-iommu.c
> @@ -0,0 +1,966 @@
> +// 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-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/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?
> + * @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 force_bypass_offset;
> +	u64 force_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 spaces.
> + * 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}
> + * @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;
> +
> +	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);
> +		apple_dart_hw_enable_translation(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)
> +		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_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;
> +}
> +
> +/* must be called with held dart_domain->lock */

You can remove this comment, include lockdep.h and…

> +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);

A lockdep enabled kernel will warn if this function is called without
the lock held, otherwise this gets optimized out. Same for the similar
comments below.

> +	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;
> +
> +	// HACK: create a static pagetable to fake bypass mode
> +	if (domain->type == IOMMU_DOMAIN_IDENTITY) {
> +		u64 addr;
> +
> +		for (addr = 0; addr < dart->force_bypass_len;
> +		     addr += dart->pgsize)
> +			dart_domain->pgtbl_ops->map(
> +				dart_domain->pgtbl_ops, addr,
> +				dart->force_bypass_offset + addr, dart->pgsize,
> +				IOMMU_READ | IOMMU_WRITE, GFP_ATOMIC);
> +	}
> +
> +	return 0;
> +}
> +
> +static void apple_dart_stream_setup_ttbrs(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);
> +}
> +
> +/* must be called with held domain->lock */
> +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;
> +
> +	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_ttbrs(domain, stream->dart,
> +						      stream->sid);
> +			apple_dart_hw_enable_translation(stream->dart,
> +							 stream->sid);
> +			apple_dart_hw_invalidate_tlb_stream(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_ttbrs(domain, stream->dart,
> +					      stream->sid);
> +		apple_dart_hw_enable_translation(stream->dart, stream->sid);
> +		apple_dart_hw_invalidate_tlb_stream(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);
> +}
> +
> +/* must be called with held domain->lock */
> +static void apple_dart_detach_stream(struct apple_dart_domain *domain,
> +				     struct apple_dart *dart, u32 sid)
> +{
> +	struct apple_dart_stream *stream;
> +
> +	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;
> +
> +	spin_lock_irqsave(&dart_domain->lock, flags);
> +
> +	if (!dart_domain->dart)
> +		dart_domain->dart = 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");
> +		ret = -EINVAL;
> +		goto out;
> +	}
> +
> +	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 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,
> +	.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)
> +		return ret;
> +
> +	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;
> +
> +	// HACK: these shouldn't be hardcoded here but come from the device tree
> +	dart->force_bypass_offset = 0x0800000000;
> +	dart->force_bypass_len = 0x0100000000;
> +
> +	dart->irq = platform_get_irq(pdev, 0);
> +	if (dart->irq < 0)
> +		return -ENODEV;
> +
> +	ret = devm_request_irq(dart->dev, dart->irq, apple_dart_irq,
> +			       IRQF_SHARED, "apple-dart fault handler", dart);
> +	if (ret)
> +		return ret;
> +
> +	platform_set_drvdata(pdev, dart);
> +
> +	ret = iommu_device_sysfs_add(&dart->iommu, dev, NULL, "apple-dart.%s",
> +				     dev_name(&pdev->dev));
> +	if (ret)
> +		return ret;
> +
> +	ret = iommu_device_register(&dart->iommu, &apple_dart_iommu_ops, dev);
> +	if (ret)
> +		return ret;
> +
> +	if (dev->bus->iommu_ops != &apple_dart_iommu_ops) {
> +		ret = bus_set_iommu(dev->bus, &apple_dart_iommu_ops);
> +		if (ret)
> +			return ret;
> +	}
> +#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)
> +			return ret;
> +	}
> +#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;
> +}
> +
> +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");

Regards,
Rouven



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Re: [PATCH v3 3/3] iommu: dart: Add DART iommu driver

[Sven Peter]

Hi Rouven,

On Sat, Jun 5, 2021, at 13:50, Rouven Czerwinski wrote:
> Hi Sven,
> 
> just a small comment, see inline.
> 
> On Thu, 2021-06-03 at 10:50 +0200, Sven Peter wrote:
> > +
> > +/* must be called with held dart_domain->lock */
> 
> You can remove this comment, include lockdep.h and…
> 
> > +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);
> 
> A lockdep enabled kernel will warn if this function is called without
> the lock held, otherwise this gets optimized out. Same for the similar
> comments below.
> 

That looks very useful, thanks! Will use it for v4.

I only found assert_spin_locked originally but didn't want to have that
performance overhead for code that (I hope :-)) correctly uses these functions
with a held lock right now.


Thanks,


Sven


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Re: [PATCH v3 2/3] dt-bindings: iommu: add DART iommu bindings

[Rob Herring]

On Thu, Jun 03, 2021 at 10:50:02AM +0200, Sven Peter wrote:
> DART (Device Address Resolution Table) is the iommu found on Apple
> ARM SoCs such as the M1.
> 
> Signed-off-by: Sven Peter <sven@svenpeter.dev>
> ---
>  .../devicetree/bindings/iommu/apple,dart.yaml | 81 +++++++++++++++++++
>  MAINTAINERS                                   |  6 ++
>  2 files changed, 87 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/iommu/apple,dart.yaml
> 
> diff --git a/Documentation/devicetree/bindings/iommu/apple,dart.yaml b/Documentation/devicetree/bindings/iommu/apple,dart.yaml
> new file mode 100644
> index 000000000000..db21ca07d121
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iommu/apple,dart.yaml
> @@ -0,0 +1,81 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/iommu/apple,dart.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Apple DART IOMMU
> +
> +maintainers:
> +  - Sven Peter <sven@svenpeter.dev>
> +
> +description: |+
> +  Apple SoCs may contain an implementation of their Device Address
> +  Resolution Table which provides a mandatory layer of address
> +  translations for various masters.
> +
> +  Each DART instance is capable of handling up to 16 different streams
> +  with individual pagetables and page-level read/write protection flags.
> +
> +  This DART IOMMU also raises interrupts in response to various
> +  fault conditions.
> +
> +properties:
> +  compatible:
> +    const: apple,t8103-dart
> +
> +  reg:
> +    maxItems: 1
> +
> +  interrupts:
> +    maxItems: 1
> +
> +  clocks:
> +    description:
> +      Reference to the gate clock phandle if required for this IOMMU.
> +      Optional since not all IOMMUs are attached to a clock gate.
> +
> +  '#iommu-cells':
> +    const: 1
> +    description:
> +      Has to be one. The single cell describes the stream id emitted by
> +      a master to the IOMMU.
> +
> +required:
> +  - compatible
> +  - reg
> +  - '#iommu-cells'
> +  - interrupts
> +
> +additionalProperties: false
> +
> +examples:
> +  - |+
> +    dart1: iommu@82f80000 {
> +      compatible = "apple,t8103-dart";
> +      reg = <0x82f80000 0x4000>;
> +      interrupts = <1 781 4>;
> +      #iommu-cells = <1>;
> +    };
> +
> +    master1 {
> +      iommus = <&{/dart1} 0>;

/dart1 is a path, but 'dart1' is a label. You need '&dart1' (or 
'&{/iommu@82f80000}' but that doesn't really work here because the 
examples get prefixed with /example-n/...)

With that fixed,

Reviewed-by: Rob Herring <robh@kernel.org>


> +    };
> +
> +  - |+
> +    dart2a: iommu@82f00000 {
> +      compatible = "apple,t8103-dart";
> +      reg = <0x82f00000 0x4000>;
> +      interrupts = <1 781 4>;
> +      #iommu-cells = <1>;
> +    };
> +    dart2b: iommu@82f80000 {
> +      compatible = "apple,t8103-dart";
> +      reg = <0x82f80000 0x4000>;
> +      interrupts = <1 781 4>;
> +      #iommu-cells = <1>;
> +    };
> +
> +    master2 {
> +      iommus = <&{/dart2a} 0>, <&{/dart2b} 1>;
> +    };
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 673cadd5107a..4373d63f9ccf 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -1240,6 +1240,12 @@ L:	linux-input@vger.kernel.org
>  S:	Odd fixes
>  F:	drivers/input/mouse/bcm5974.c
>  
> +APPLE DART IOMMU DRIVER
> +M:	Sven Peter <sven@svenpeter.dev>
> +L:	iommu@lists.linux-foundation.org
> +S:	Maintained
> +F:	Documentation/devicetree/bindings/iommu/apple,dart.yaml
> +
>  APPLE SMC DRIVER
>  M:	Henrik Rydberg <rydberg@bitmath.org>
>  L:	linux-hwmon@vger.kernel.org
> -- 
> 2.25.1

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Re: [PATCH v3 2/3] dt-bindings: iommu: add DART iommu bindings

[Sven Peter]

Hi,

On Thu, Jun 10, 2021, at 18:52, Rob Herring wrote:
> On Thu, Jun 03, 2021 at 10:50:02AM +0200, Sven Peter wrote:
> > +
> > +examples:
> > +  - |+
> > +    dart1: iommu@82f80000 {
> > +      compatible = "apple,t8103-dart";
> > +      reg = <0x82f80000 0x4000>;
> > +      interrupts = <1 781 4>;
> > +      #iommu-cells = <1>;
> > +    };
> > +
> > +    master1 {
> > +      iommus = <&{/dart1} 0>;
> 
> /dart1 is a path, but 'dart1' is a label. You need '&dart1' (or 
> '&{/iommu@82f80000}' but that doesn't really work here because the 
> examples get prefixed with /example-n/...)
> 
> With that fixed,
> 
> Reviewed-by: Rob Herring <robh@kernel.org>

Makes sense, thanks for the review!
Fixed for the next version.


Sven

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