Re: [PATCH v2 2/7] iommu/riscv: Add RISC-V IOMMU platform device driver

From: Robin Murphy <robin.murphy@arm.com>
To: Tomasz Jeznach <tjeznach@rivosinc.com>,
	Joerg Roedel <joro@8bytes.org>, Will Deacon <will@kernel.org>,
	Paul Walmsley <paul.walmsley@sifive.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>,
	Albert Ou <aou@eecs.berkeley.edu>,
	Anup Patel <apatel@ventanamicro.com>,
	Sunil V L <sunilvl@ventanamicro.com>,
	Nick Kossifidis <mick@ics.forth.gr>,
	Sebastien Boeuf <seb@rivosinc.com>,
	Rob Herring <robh+dt@kernel.org>,
	Krzysztof Kozlowski <krzk+dt@kernel.org>,
	Conor Dooley <conor+dt@kernel.org>,
	devicetree@vger.kernel.org, iommu@lists.linux.dev,
	linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
	linux@rivosinc.com
Subject: Re: [PATCH v2 2/7] iommu/riscv: Add RISC-V IOMMU platform device driver
Date: Thu, 18 Apr 2024 22:22:13 +0100	[thread overview]
Message-ID: <7f9a82ea-c4c8-40a5-8f26-7cb135e91c5d@arm.com> (raw)
In-Reply-To: <741996169fef074b5d9f4f218c2a98bf5dd38386.1713456598.git.tjeznach@rivosinc.com>

On 2024-04-18 5:32 pm, Tomasz Jeznach wrote:
> Introduce platform device driver for implementation of RISC-V IOMMU
> architected hardware.
> 
> Hardware interface definition located in file iommu-bits.h is based on
> ratified RISC-V IOMMU Architecture Specification version 1.0.0.
> 
> This patch implements platform device initialization, early check and
> configuration of the IOMMU interfaces and enables global pass-through
> address translation mode (iommu_mode == BARE), without registering
> hardware instance in the IOMMU subsystem.
> 
> Link: https://github.com/riscv-non-isa/riscv-iommu
> Co-developed-by: Nick Kossifidis <mick@ics.forth.gr>
> Signed-off-by: Nick Kossifidis <mick@ics.forth.gr>
> Co-developed-by: Sebastien Boeuf <seb@rivosinc.com>
> Signed-off-by: Sebastien Boeuf <seb@rivosinc.com>
> Signed-off-by: Tomasz Jeznach <tjeznach@rivosinc.com>
> ---
>   MAINTAINERS                          |   6 +
>   drivers/iommu/Kconfig                |   1 +
>   drivers/iommu/Makefile               |   2 +-
>   drivers/iommu/riscv/Kconfig          |  16 +
>   drivers/iommu/riscv/Makefile         |   2 +
>   drivers/iommu/riscv/iommu-bits.h     | 707 +++++++++++++++++++++++++++
>   drivers/iommu/riscv/iommu-platform.c |  94 ++++
>   drivers/iommu/riscv/iommu.c          |  89 ++++
>   drivers/iommu/riscv/iommu.h          |  62 +++
>   9 files changed, 978 insertions(+), 1 deletion(-)
>   create mode 100644 drivers/iommu/riscv/Kconfig
>   create mode 100644 drivers/iommu/riscv/Makefile
>   create mode 100644 drivers/iommu/riscv/iommu-bits.h
>   create mode 100644 drivers/iommu/riscv/iommu-platform.c
>   create mode 100644 drivers/iommu/riscv/iommu.c
>   create mode 100644 drivers/iommu/riscv/iommu.h
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 2657f9eae84c..051599c76585 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -18972,6 +18972,12 @@ L:	iommu@lists.linux.dev
>   L:	linux-riscv@lists.infradead.org
>   S:	Maintained
>   F:	Documentation/devicetree/bindings/iommu/riscv,iommu.yaml
> +F:	drivers/iommu/riscv/Kconfig
> +F:	drivers/iommu/riscv/Makefile
> +F:	drivers/iommu/riscv/iommu-bits.h
> +F:	drivers/iommu/riscv/iommu-platform.c
> +F:	drivers/iommu/riscv/iommu.c
> +F:	drivers/iommu/riscv/iommu.h

I'm pretty sure a single "F: drivers/iommu/riscv/" pattern will suffice.

>   RISC-V MICROCHIP FPGA SUPPORT
>   M:	Conor Dooley <conor.dooley@microchip.com>
> diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
> index 0af39bbbe3a3..ae762db0365e 100644
> --- a/drivers/iommu/Kconfig
> +++ b/drivers/iommu/Kconfig
> @@ -195,6 +195,7 @@ config MSM_IOMMU
>   source "drivers/iommu/amd/Kconfig"
>   source "drivers/iommu/intel/Kconfig"
>   source "drivers/iommu/iommufd/Kconfig"
> +source "drivers/iommu/riscv/Kconfig"
>   
>   config IRQ_REMAP
>   	bool "Support for Interrupt Remapping"
> diff --git a/drivers/iommu/Makefile b/drivers/iommu/Makefile
> index 542760d963ec..5e5a83c6c2aa 100644
> --- a/drivers/iommu/Makefile
> +++ b/drivers/iommu/Makefile
> @@ -1,5 +1,5 @@
>   # SPDX-License-Identifier: GPL-2.0
> -obj-y += amd/ intel/ arm/ iommufd/
> +obj-y += amd/ intel/ arm/ iommufd/ riscv/
>   obj-$(CONFIG_IOMMU_API) += iommu.o
>   obj-$(CONFIG_IOMMU_API) += iommu-traces.o
>   obj-$(CONFIG_IOMMU_API) += iommu-sysfs.o
> diff --git a/drivers/iommu/riscv/Kconfig b/drivers/iommu/riscv/Kconfig
> new file mode 100644
> index 000000000000..d02326bddb4c
> --- /dev/null
> +++ b/drivers/iommu/riscv/Kconfig
> @@ -0,0 +1,16 @@
> +# SPDX-License-Identifier: GPL-2.0-only
> +# RISC-V IOMMU support
> +
> +config RISCV_IOMMU
> +	def_bool y if RISCV && 64BIT && MMU

Drop the dependencies here, they're already dependencies. However, also 
consider allowing users to configure this out without disabling 
IOMMU_SUPPORT entirely - I imagine other IOMMU implementations are going 
to end up paired wiothg RISC-V CPUs sooner or later. Furthermore, if 
it's a regular driver model driver, consider allowing it to build as a 
module. Not to mention that the help text below is rather pointless if 
there's no prompt offered in the first place.

> +	depends on RISCV && 64BIT && MMU
> +	select DMA_OPS

Drop this, you're not (and shouldn't be) architecture code implementing 
DMA ops.

> +	select IOMMU_API
> +	select IOMMU_IOVA

Drop this, you're not using the IOVA library either.

> +	help
> +	  Support for implementations of the RISC-V IOMMU architecture that
> +	  complements the RISC-V MMU capabilities, providing similar address
> +	  translation and protection functions for accesses from I/O devices.
> +
> +	  Say Y here if your SoC includes an IOMMU device implementing
> +	  the RISC-V IOMMU architecture.
> diff --git a/drivers/iommu/riscv/Makefile b/drivers/iommu/riscv/Makefile
> new file mode 100644
> index 000000000000..e4c189de58d3
> --- /dev/null
> +++ b/drivers/iommu/riscv/Makefile
> @@ -0,0 +1,2 @@
> +# SPDX-License-Identifier: GPL-2.0-only
> +obj-$(CONFIG_RISCV_IOMMU) += iommu.o iommu-platform.o
> diff --git a/drivers/iommu/riscv/iommu-bits.h b/drivers/iommu/riscv/iommu-bits.h
> new file mode 100644
> index 000000000000..ba093c29de9f
> --- /dev/null
> +++ b/drivers/iommu/riscv/iommu-bits.h
> @@ -0,0 +1,707 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * Copyright © 2022-2024 Rivos Inc.
> + * Copyright © 2023 FORTH-ICS/CARV
> + * Copyright © 2023 RISC-V IOMMU Task Group
> + *
> + * RISC-V IOMMU - Register Layout and Data Structures.
> + *
> + * Based on the 'RISC-V IOMMU Architecture Specification', Version 1.0
> + * Published at  https://github.com/riscv-non-isa/riscv-iommu
> + *
> + */
> +
> +#ifndef _RISCV_IOMMU_BITS_H_
> +#define _RISCV_IOMMU_BITS_H_
> +
> +#include <linux/types.h>
> +#include <linux/bitfield.h>
> +#include <linux/bits.h>
> +
> +/*
> + * Chapter 5: Memory Mapped register interface
> + */
> +
> +/* Common field positions */
> +#define RISCV_IOMMU_PPN_FIELD		GENMASK_ULL(53, 10)
> +#define RISCV_IOMMU_QUEUE_LOGSZ_FIELD	GENMASK_ULL(4, 0)
> +#define RISCV_IOMMU_QUEUE_INDEX_FIELD	GENMASK_ULL(31, 0)
> +#define RISCV_IOMMU_QUEUE_ENABLE	BIT(0)
> +#define RISCV_IOMMU_QUEUE_INTR_ENABLE	BIT(1)
> +#define RISCV_IOMMU_QUEUE_MEM_FAULT	BIT(8)
> +#define RISCV_IOMMU_QUEUE_OVERFLOW	BIT(9)
> +#define RISCV_IOMMU_QUEUE_ACTIVE	BIT(16)
> +#define RISCV_IOMMU_QUEUE_BUSY		BIT(17)
> +
> +#define RISCV_IOMMU_ATP_PPN_FIELD	GENMASK_ULL(43, 0)
> +#define RISCV_IOMMU_ATP_MODE_FIELD	GENMASK_ULL(63, 60)
> +
> +/* 5.3 IOMMU Capabilities (64bits) */
> +#define RISCV_IOMMU_REG_CAP		0x0000
> +#define RISCV_IOMMU_CAP_VERSION		GENMASK_ULL(7, 0)
> +#define RISCV_IOMMU_CAP_S_SV32		BIT_ULL(8)
> +#define RISCV_IOMMU_CAP_S_SV39		BIT_ULL(9)
> +#define RISCV_IOMMU_CAP_S_SV48		BIT_ULL(10)
> +#define RISCV_IOMMU_CAP_S_SV57		BIT_ULL(11)
> +#define RISCV_IOMMU_CAP_SVPBMT		BIT_ULL(15)
> +#define RISCV_IOMMU_CAP_G_SV32		BIT_ULL(16)
> +#define RISCV_IOMMU_CAP_G_SV39		BIT_ULL(17)
> +#define RISCV_IOMMU_CAP_G_SV48		BIT_ULL(18)
> +#define RISCV_IOMMU_CAP_G_SV57		BIT_ULL(19)
> +#define RISCV_IOMMU_CAP_AMO_MRIF	BIT_ULL(21)
> +#define RISCV_IOMMU_CAP_MSI_FLAT	BIT_ULL(22)
> +#define RISCV_IOMMU_CAP_MSI_MRIF	BIT_ULL(23)
> +#define RISCV_IOMMU_CAP_AMO_HWAD	BIT_ULL(24)
> +#define RISCV_IOMMU_CAP_ATS		BIT_ULL(25)
> +#define RISCV_IOMMU_CAP_T2GPA		BIT_ULL(26)
> +#define RISCV_IOMMU_CAP_END		BIT_ULL(27)
> +#define RISCV_IOMMU_CAP_IGS		GENMASK_ULL(29, 28)
> +#define RISCV_IOMMU_CAP_HPM		BIT_ULL(30)
> +#define RISCV_IOMMU_CAP_DBG		BIT_ULL(31)
> +#define RISCV_IOMMU_CAP_PAS		GENMASK_ULL(37, 32)
> +#define RISCV_IOMMU_CAP_PD8		BIT_ULL(38)
> +#define RISCV_IOMMU_CAP_PD17		BIT_ULL(39)
> +#define RISCV_IOMMU_CAP_PD20		BIT_ULL(40)
> +
> +#define RISCV_IOMMU_CAP_VERSION_VER_MASK	0xF0
> +#define RISCV_IOMMU_CAP_VERSION_REV_MASK	0x0F
> +
> +/**
> + * enum riscv_iommu_igs_settings - Interrupt Generation Support Settings
> + * @RISCV_IOMMU_CAP_IGS_MSI: I/O MMU supports only MSI generation
> + * @RISCV_IOMMU_CAP_IGS_WSI: I/O MMU supports only Wired-Signaled interrupt
> + * @RISCV_IOMMU_CAP_IGS_BOTH: I/O MMU supports both MSI and WSI generation
> + * @RISCV_IOMMU_CAP_IGS_RSRV: Reserved for standard use
> + */
> +enum riscv_iommu_igs_settings {
> +	RISCV_IOMMU_CAP_IGS_MSI = 0,
> +	RISCV_IOMMU_CAP_IGS_WSI = 1,
> +	RISCV_IOMMU_CAP_IGS_BOTH = 2,
> +	RISCV_IOMMU_CAP_IGS_RSRV = 3
> +};
> +
> +/* 5.4 Features control register (32bits) */
> +#define RISCV_IOMMU_REG_FCTL		0x0008
> +#define RISCV_IOMMU_FCTL_BE		BIT(0)
> +#define RISCV_IOMMU_FCTL_WSI		BIT(1)
> +#define RISCV_IOMMU_FCTL_GXL		BIT(2)
> +
> +/* 5.5 Device-directory-table pointer (64bits) */
> +#define RISCV_IOMMU_REG_DDTP		0x0010
> +#define RISCV_IOMMU_DDTP_MODE		GENMASK_ULL(3, 0)
> +#define RISCV_IOMMU_DDTP_BUSY		BIT_ULL(4)
> +#define RISCV_IOMMU_DDTP_PPN		RISCV_IOMMU_PPN_FIELD
> +
> +/**
> + * enum riscv_iommu_ddtp_modes - I/O MMU translation modes
> + * @RISCV_IOMMU_DDTP_MODE_OFF: No inbound transactions allowed
> + * @RISCV_IOMMU_DDTP_MODE_BARE: Pass-through mode
> + * @RISCV_IOMMU_DDTP_MODE_1LVL: One-level DDT
> + * @RISCV_IOMMU_DDTP_MODE_2LVL: Two-level DDT
> + * @RISCV_IOMMU_DDTP_MODE_3LVL: Three-level DDT
> + * @RISCV_IOMMU_DDTP_MODE_MAX: Max value allowed by specification
> + */
> +enum riscv_iommu_ddtp_modes {
> +	RISCV_IOMMU_DDTP_MODE_OFF = 0,
> +	RISCV_IOMMU_DDTP_MODE_BARE = 1,
> +	RISCV_IOMMU_DDTP_MODE_1LVL = 2,
> +	RISCV_IOMMU_DDTP_MODE_2LVL = 3,
> +	RISCV_IOMMU_DDTP_MODE_3LVL = 4,
> +	RISCV_IOMMU_DDTP_MODE_MAX = 4
> +};
> +
> +/* 5.6 Command Queue Base (64bits) */
> +#define RISCV_IOMMU_REG_CQB		0x0018
> +#define RISCV_IOMMU_CQB_ENTRIES		RISCV_IOMMU_QUEUE_LOGSZ_FIELD
> +#define RISCV_IOMMU_CQB_PPN		RISCV_IOMMU_PPN_FIELD
> +
> +/* 5.7 Command Queue head (32bits) */
> +#define RISCV_IOMMU_REG_CQH		0x0020
> +#define RISCV_IOMMU_CQH_INDEX		RISCV_IOMMU_QUEUE_INDEX_FIELD
> +
> +/* 5.8 Command Queue tail (32bits) */
> +#define RISCV_IOMMU_REG_CQT		0x0024
> +#define RISCV_IOMMU_CQT_INDEX		RISCV_IOMMU_QUEUE_INDEX_FIELD
> +
> +/* 5.9 Fault Queue Base (64bits) */
> +#define RISCV_IOMMU_REG_FQB		0x0028
> +#define RISCV_IOMMU_FQB_ENTRIES		RISCV_IOMMU_QUEUE_LOGSZ_FIELD
> +#define RISCV_IOMMU_FQB_PPN		RISCV_IOMMU_PPN_FIELD
> +
> +/* 5.10 Fault Queue Head (32bits) */
> +#define RISCV_IOMMU_REG_FQH		0x0030
> +#define RISCV_IOMMU_FQH_INDEX		RISCV_IOMMU_QUEUE_INDEX_FIELD
> +
> +/* 5.11 Fault Queue tail (32bits) */
> +#define RISCV_IOMMU_REG_FQT		0x0034
> +#define RISCV_IOMMU_FQT_INDEX		RISCV_IOMMU_QUEUE_INDEX_FIELD
> +
> +/* 5.12 Page Request Queue base (64bits) */
> +#define RISCV_IOMMU_REG_PQB		0x0038
> +#define RISCV_IOMMU_PQB_ENTRIES		RISCV_IOMMU_QUEUE_LOGSZ_FIELD
> +#define RISCV_IOMMU_PQB_PPN		RISCV_IOMMU_PPN_FIELD
> +
> +/* 5.13 Page Request Queue head (32bits) */
> +#define RISCV_IOMMU_REG_PQH		0x0040
> +#define RISCV_IOMMU_PQH_INDEX		RISCV_IOMMU_QUEUE_INDEX_FIELD
> +
> +/* 5.14 Page Request Queue tail (32bits) */
> +#define RISCV_IOMMU_REG_PQT		0x0044
> +#define RISCV_IOMMU_PQT_INDEX_MASK	RISCV_IOMMU_QUEUE_INDEX_FIELD
> +
> +/* 5.15 Command Queue CSR (32bits) */
> +#define RISCV_IOMMU_REG_CQCSR		0x0048
> +#define RISCV_IOMMU_CQCSR_CQEN		RISCV_IOMMU_QUEUE_ENABLE
> +#define RISCV_IOMMU_CQCSR_CIE		RISCV_IOMMU_QUEUE_INTR_ENABLE
> +#define RISCV_IOMMU_CQCSR_CQMF		RISCV_IOMMU_QUEUE_MEM_FAULT
> +#define RISCV_IOMMU_CQCSR_CMD_TO	BIT(9)
> +#define RISCV_IOMMU_CQCSR_CMD_ILL	BIT(10)
> +#define RISCV_IOMMU_CQCSR_FENCE_W_IP	BIT(11)
> +#define RISCV_IOMMU_CQCSR_CQON		RISCV_IOMMU_QUEUE_ACTIVE
> +#define RISCV_IOMMU_CQCSR_BUSY		RISCV_IOMMU_QUEUE_BUSY
> +
> +/* 5.16 Fault Queue CSR (32bits) */
> +#define RISCV_IOMMU_REG_FQCSR		0x004C
> +#define RISCV_IOMMU_FQCSR_FQEN		RISCV_IOMMU_QUEUE_ENABLE
> +#define RISCV_IOMMU_FQCSR_FIE		RISCV_IOMMU_QUEUE_INTR_ENABLE
> +#define RISCV_IOMMU_FQCSR_FQMF		RISCV_IOMMU_QUEUE_MEM_FAULT
> +#define RISCV_IOMMU_FQCSR_FQOF		RISCV_IOMMU_QUEUE_OVERFLOW
> +#define RISCV_IOMMU_FQCSR_FQON		RISCV_IOMMU_QUEUE_ACTIVE
> +#define RISCV_IOMMU_FQCSR_BUSY		RISCV_IOMMU_QUEUE_BUSY
> +
> +/* 5.17 Page Request Queue CSR (32bits) */
> +#define RISCV_IOMMU_REG_PQCSR		0x0050
> +#define RISCV_IOMMU_PQCSR_PQEN		RISCV_IOMMU_QUEUE_ENABLE
> +#define RISCV_IOMMU_PQCSR_PIE		RISCV_IOMMU_QUEUE_INTR_ENABLE
> +#define RISCV_IOMMU_PQCSR_PQMF		RISCV_IOMMU_QUEUE_MEM_FAULT
> +#define RISCV_IOMMU_PQCSR_PQOF		RISCV_IOMMU_QUEUE_OVERFLOW
> +#define RISCV_IOMMU_PQCSR_PQON		RISCV_IOMMU_QUEUE_ACTIVE
> +#define RISCV_IOMMU_PQCSR_BUSY		RISCV_IOMMU_QUEUE_BUSY
> +
> +/* 5.18 Interrupt Pending Status (32bits) */
> +#define RISCV_IOMMU_REG_IPSR		0x0054
> +
> +#define RISCV_IOMMU_INTR_CQ		0
> +#define RISCV_IOMMU_INTR_FQ		1
> +#define RISCV_IOMMU_INTR_PM		2
> +#define RISCV_IOMMU_INTR_PQ		3
> +#define RISCV_IOMMU_INTR_COUNT		4
> +
> +#define RISCV_IOMMU_IPSR_CIP		BIT(RISCV_IOMMU_INTR_CQ)
> +#define RISCV_IOMMU_IPSR_FIP		BIT(RISCV_IOMMU_INTR_FQ)
> +#define RISCV_IOMMU_IPSR_PMIP		BIT(RISCV_IOMMU_INTR_PM)
> +#define RISCV_IOMMU_IPSR_PIP		BIT(RISCV_IOMMU_INTR_PQ)
> +
> +/* 5.19 Performance monitoring counter overflow status (32bits) */
> +#define RISCV_IOMMU_REG_IOCOUNTOVF	0x0058
> +#define RISCV_IOMMU_IOCOUNTOVF_CY	BIT(0)
> +#define RISCV_IOMMU_IOCOUNTOVF_HPM	GENMASK_ULL(31, 1)
> +
> +/* 5.20 Performance monitoring counter inhibits (32bits) */
> +#define RISCV_IOMMU_REG_IOCOUNTINH	0x005C
> +#define RISCV_IOMMU_IOCOUNTINH_CY	BIT(0)
> +#define RISCV_IOMMU_IOCOUNTINH_HPM	GENMASK(31, 1)
> +
> +/* 5.21 Performance monitoring cycles counter (64bits) */
> +#define RISCV_IOMMU_REG_IOHPMCYCLES     0x0060
> +#define RISCV_IOMMU_IOHPMCYCLES_COUNTER	GENMASK_ULL(62, 0)
> +#define RISCV_IOMMU_IOHPMCYCLES_OVF	BIT_ULL(63)
> +
> +/* 5.22 Performance monitoring event counters (31 * 64bits) */
> +#define RISCV_IOMMU_REG_IOHPMCTR_BASE	0x0068
> +#define RISCV_IOMMU_REG_IOHPMCTR(_n)	(RISCV_IOMMU_REG_IOHPMCTR_BASE + ((_n) * 0x8))
> +
> +/* 5.23 Performance monitoring event selectors (31 * 64bits) */
> +#define RISCV_IOMMU_REG_IOHPMEVT_BASE	0x0160
> +#define RISCV_IOMMU_REG_IOHPMEVT(_n)	(RISCV_IOMMU_REG_IOHPMEVT_BASE + ((_n) * 0x8))
> +#define RISCV_IOMMU_IOHPMEVT_CNT	31
> +#define RISCV_IOMMU_IOHPMEVT_EVENT_ID	GENMASK_ULL(14, 0)
> +#define RISCV_IOMMU_IOHPMEVT_DMASK	BIT_ULL(15)
> +#define RISCV_IOMMU_IOHPMEVT_PID_PSCID	GENMASK_ULL(35, 16)
> +#define RISCV_IOMMU_IOHPMEVT_DID_GSCID	GENMASK_ULL(59, 36)
> +#define RISCV_IOMMU_IOHPMEVT_PV_PSCV	BIT_ULL(60)
> +#define RISCV_IOMMU_IOHPMEVT_DV_GSCV	BIT_ULL(61)
> +#define RISCV_IOMMU_IOHPMEVT_IDT	BIT_ULL(62)
> +#define RISCV_IOMMU_IOHPMEVT_OF		BIT_ULL(63)
> +
> +/**
> + * enum riscv_iommu_hpmevent_id - Performance-monitoring event identifier
> + *
> + * @RISCV_IOMMU_HPMEVENT_INVALID: Invalid event, do not count
> + * @RISCV_IOMMU_HPMEVENT_URQ: Untranslated requests
> + * @RISCV_IOMMU_HPMEVENT_TRQ: Translated requests
> + * @RISCV_IOMMU_HPMEVENT_ATS_RQ: ATS translation requests
> + * @RISCV_IOMMU_HPMEVENT_TLB_MISS: TLB misses
> + * @RISCV_IOMMU_HPMEVENT_DD_WALK: Device directory walks
> + * @RISCV_IOMMU_HPMEVENT_PD_WALK: Process directory walks
> + * @RISCV_IOMMU_HPMEVENT_S_VS_WALKS: S/VS-Stage page table walks
> + * @RISCV_IOMMU_HPMEVENT_G_WALKS: G-Stage page table walks
> + * @RISCV_IOMMU_HPMEVENT_MAX: Value to denote maximum Event IDs
> + */
> +enum riscv_iommu_hpmevent_id {
> +	RISCV_IOMMU_HPMEVENT_INVALID    = 0,
> +	RISCV_IOMMU_HPMEVENT_URQ        = 1,
> +	RISCV_IOMMU_HPMEVENT_TRQ        = 2,
> +	RISCV_IOMMU_HPMEVENT_ATS_RQ     = 3,
> +	RISCV_IOMMU_HPMEVENT_TLB_MISS   = 4,
> +	RISCV_IOMMU_HPMEVENT_DD_WALK    = 5,
> +	RISCV_IOMMU_HPMEVENT_PD_WALK    = 6,
> +	RISCV_IOMMU_HPMEVENT_S_VS_WALKS = 7,
> +	RISCV_IOMMU_HPMEVENT_G_WALKS    = 8,
> +	RISCV_IOMMU_HPMEVENT_MAX        = 9
> +};
> +
> +/* 5.24 Translation request IOVA (64bits) */
> +#define RISCV_IOMMU_REG_TR_REQ_IOVA     0x0258
> +#define RISCV_IOMMU_TR_REQ_IOVA_VPN	GENMASK_ULL(63, 12)
> +
> +/* 5.25 Translation request control (64bits) */
> +#define RISCV_IOMMU_REG_TR_REQ_CTL	0x0260
> +#define RISCV_IOMMU_TR_REQ_CTL_GO_BUSY	BIT_ULL(0)
> +#define RISCV_IOMMU_TR_REQ_CTL_PRIV	BIT_ULL(1)
> +#define RISCV_IOMMU_TR_REQ_CTL_EXE	BIT_ULL(2)
> +#define RISCV_IOMMU_TR_REQ_CTL_NW	BIT_ULL(3)
> +#define RISCV_IOMMU_TR_REQ_CTL_PID	GENMASK_ULL(31, 12)
> +#define RISCV_IOMMU_TR_REQ_CTL_PV	BIT_ULL(32)
> +#define RISCV_IOMMU_TR_REQ_CTL_DID	GENMASK_ULL(63, 40)
> +
> +/* 5.26 Translation request response (64bits) */
> +#define RISCV_IOMMU_REG_TR_RESPONSE	0x0268
> +#define RISCV_IOMMU_TR_RESPONSE_FAULT	BIT_ULL(0)
> +#define RISCV_IOMMU_TR_RESPONSE_PBMT	GENMASK_ULL(8, 7)
> +#define RISCV_IOMMU_TR_RESPONSE_SZ	BIT_ULL(9)
> +#define RISCV_IOMMU_TR_RESPONSE_PPN	RISCV_IOMMU_PPN_FIELD
> +
> +/* 5.27 Interrupt cause to vector (64bits) */
> +#define RISCV_IOMMU_REG_IVEC		0x02F8
> +#define RISCV_IOMMU_IVEC_CIV		GENMASK_ULL(3, 0)
> +#define RISCV_IOMMU_IVEC_FIV		GENMASK_ULL(7, 4)
> +#define RISCV_IOMMU_IVEC_PMIV		GENMASK_ULL(11, 8)
> +#define RISCV_IOMMU_IVEC_PIV		GENMASK_ULL(15, 12)
> +
> +/* 5.28 MSI Configuration table (32 * 64bits) */
> +#define RISCV_IOMMU_REG_MSI_CONFIG	0x0300
> +#define RISCV_IOMMU_REG_MSI_ADDR(_n)	(RISCV_IOMMU_REG_MSI_CONFIG + ((_n) * 0x10))
> +#define RISCV_IOMMU_MSI_ADDR		GENMASK_ULL(55, 2)
> +#define RISCV_IOMMU_REG_MSI_DATA(_n)	(RISCV_IOMMU_REG_MSI_CONFIG + ((_n) * 0x10) + 0x08)
> +#define RISCV_IOMMU_MSI_DATA		GENMASK_ULL(31, 0)
> +#define RISCV_IOMMU_REG_MSI_VEC_CTL(_n)	(RISCV_IOMMU_REG_MSI_CONFIG + ((_n) * 0x10) + 0x0C)
> +#define RISCV_IOMMU_MSI_VEC_CTL_M	BIT_ULL(0)
> +
> +#define RISCV_IOMMU_REG_SIZE	0x1000
> +
> +/*
> + * Chapter 2: Data structures
> + */
> +
> +/*
> + * Device Directory Table macros for non-leaf nodes
> + */
> +#define RISCV_IOMMU_DDTE_VALID	BIT_ULL(0)
> +#define RISCV_IOMMU_DDTE_PPN	RISCV_IOMMU_PPN_FIELD
> +
> +/**
> + * struct riscv_iommu_dc - Device Context
> + * @tc: Translation Control
> + * @iohgatp: I/O Hypervisor guest address translation and protection
> + *	     (Second stage context)
> + * @ta: Translation Attributes
> + * @fsc: First stage context
> + * @msiptp: MSI page table pointer
> + * @msi_addr_mask: MSI address mask
> + * @msi_addr_pattern: MSI address pattern
> + * @_reserved: Reserved for future use, padding
> + *
> + * This structure is used for leaf nodes on the Device Directory Table,
> + * in case RISCV_IOMMU_CAP_MSI_FLAT is not set, the bottom 4 fields are
> + * not present and are skipped with pointer arithmetic to avoid
> + * casting, check out riscv_iommu_get_dc().
> + * See section 2.1 for more details
> + */
> +struct riscv_iommu_dc {
> +	u64 tc;
> +	u64 iohgatp;
> +	u64 ta;
> +	u64 fsc;
> +	u64 msiptp;
> +	u64 msi_addr_mask;
> +	u64 msi_addr_pattern;
> +	u64 _reserved;
> +};
> +
> +/* Translation control fields */
> +#define RISCV_IOMMU_DC_TC_V		BIT_ULL(0)
> +#define RISCV_IOMMU_DC_TC_EN_ATS	BIT_ULL(1)
> +#define RISCV_IOMMU_DC_TC_EN_PRI	BIT_ULL(2)
> +#define RISCV_IOMMU_DC_TC_T2GPA		BIT_ULL(3)
> +#define RISCV_IOMMU_DC_TC_DTF		BIT_ULL(4)
> +#define RISCV_IOMMU_DC_TC_PDTV		BIT_ULL(5)
> +#define RISCV_IOMMU_DC_TC_PRPR		BIT_ULL(6)
> +#define RISCV_IOMMU_DC_TC_GADE		BIT_ULL(7)
> +#define RISCV_IOMMU_DC_TC_SADE		BIT_ULL(8)
> +#define RISCV_IOMMU_DC_TC_DPE		BIT_ULL(9)
> +#define RISCV_IOMMU_DC_TC_SBE		BIT_ULL(10)
> +#define RISCV_IOMMU_DC_TC_SXL		BIT_ULL(11)
> +
> +/* Second-stage (aka G-stage) context fields */
> +#define RISCV_IOMMU_DC_IOHGATP_PPN	RISCV_IOMMU_ATP_PPN_FIELD
> +#define RISCV_IOMMU_DC_IOHGATP_GSCID	GENMASK_ULL(59, 44)
> +#define RISCV_IOMMU_DC_IOHGATP_MODE	RISCV_IOMMU_ATP_MODE_FIELD
> +
> +/**
> + * enum riscv_iommu_dc_iohgatp_modes - Guest address translation/protection modes
> + * @RISCV_IOMMU_DC_IOHGATP_MODE_BARE: No translation/protection
> + * @RISCV_IOMMU_DC_IOHGATP_MODE_SV32X4: Sv32x4 (2-bit extension of Sv32), when fctl.GXL == 1
> + * @RISCV_IOMMU_DC_IOHGATP_MODE_SV39X4: Sv39x4 (2-bit extension of Sv39), when fctl.GXL == 0
> + * @RISCV_IOMMU_DC_IOHGATP_MODE_SV48X4: Sv48x4 (2-bit extension of Sv48), when fctl.GXL == 0
> + * @RISCV_IOMMU_DC_IOHGATP_MODE_SV57X4: Sv57x4 (2-bit extension of Sv57), when fctl.GXL == 0
> + */
> +enum riscv_iommu_dc_iohgatp_modes {
> +	RISCV_IOMMU_DC_IOHGATP_MODE_BARE = 0,
> +	RISCV_IOMMU_DC_IOHGATP_MODE_SV32X4 = 8,
> +	RISCV_IOMMU_DC_IOHGATP_MODE_SV39X4 = 8,
> +	RISCV_IOMMU_DC_IOHGATP_MODE_SV48X4 = 9,
> +	RISCV_IOMMU_DC_IOHGATP_MODE_SV57X4 = 10
> +};
> +
> +/* Translation attributes fields */
> +#define RISCV_IOMMU_DC_TA_PSCID		GENMASK_ULL(31, 12)
> +
> +/* First-stage context fields */
> +#define RISCV_IOMMU_DC_FSC_PPN		RISCV_IOMMU_ATP_PPN_FIELD
> +#define RISCV_IOMMU_DC_FSC_MODE		RISCV_IOMMU_ATP_MODE_FIELD
> +
> +/**
> + * enum riscv_iommu_dc_fsc_atp_modes - First stage address translation/protection modes
> + * @RISCV_IOMMU_DC_FSC_MODE_BARE: No translation/protection
> + * @RISCV_IOMMU_DC_FSC_IOSATP_MODE_SV32: Sv32, when dc.tc.SXL == 1
> + * @RISCV_IOMMU_DC_FSC_IOSATP_MODE_SV39: Sv39, when dc.tc.SXL == 0
> + * @RISCV_IOMMU_DC_FSC_IOSATP_MODE_SV48: Sv48, when dc.tc.SXL == 0
> + * @RISCV_IOMMU_DC_FSC_IOSATP_MODE_SV57: Sv57, when dc.tc.SXL == 0
> + * @RISCV_IOMMU_DC_FSC_PDTP_MODE_PD8: 1lvl PDT, 8bit process ids
> + * @RISCV_IOMMU_DC_FSC_PDTP_MODE_PD17: 2lvl PDT, 17bit process ids
> + * @RISCV_IOMMU_DC_FSC_PDTP_MODE_PD20: 3lvl PDT, 20bit process ids
> + *
> + * FSC holds IOSATP when RISCV_IOMMU_DC_TC_PDTV is 0 and PDTP otherwise.
> + * IOSATP controls the first stage address translation (same as the satp register on
> + * the RISC-V MMU), and PDTP holds the process directory table, used to select a
> + * first stage page table based on a process id (for devices that support multiple
> + * process ids).
> + */
> +enum riscv_iommu_dc_fsc_atp_modes {
> +	RISCV_IOMMU_DC_FSC_MODE_BARE = 0,
> +	RISCV_IOMMU_DC_FSC_IOSATP_MODE_SV32 = 8,
> +	RISCV_IOMMU_DC_FSC_IOSATP_MODE_SV39 = 8,
> +	RISCV_IOMMU_DC_FSC_IOSATP_MODE_SV48 = 9,
> +	RISCV_IOMMU_DC_FSC_IOSATP_MODE_SV57 = 10,
> +	RISCV_IOMMU_DC_FSC_PDTP_MODE_PD8 = 1,
> +	RISCV_IOMMU_DC_FSC_PDTP_MODE_PD17 = 2,
> +	RISCV_IOMMU_DC_FSC_PDTP_MODE_PD20 = 3
> +};
> +
> +/* MSI page table pointer */
> +#define RISCV_IOMMU_DC_MSIPTP_PPN	RISCV_IOMMU_ATP_PPN_FIELD
> +#define RISCV_IOMMU_DC_MSIPTP_MODE	RISCV_IOMMU_ATP_MODE_FIELD
> +#define RISCV_IOMMU_DC_MSIPTP_MODE_OFF	0
> +#define RISCV_IOMMU_DC_MSIPTP_MODE_FLAT	1
> +
> +/* MSI address mask */
> +#define RISCV_IOMMU_DC_MSI_ADDR_MASK	GENMASK_ULL(51, 0)
> +
> +/* MSI address pattern */
> +#define RISCV_IOMMU_DC_MSI_PATTERN	GENMASK_ULL(51, 0)
> +
> +/**
> + * struct riscv_iommu_pc - Process Context
> + * @ta: Translation Attributes
> + * @fsc: First stage context
> + *
> + * This structure is used for leaf nodes on the Process Directory Table
> + * See section 2.3 for more details
> + */
> +struct riscv_iommu_pc {
> +	u64 ta;
> +	u64 fsc;
> +};
> +
> +/* Translation attributes fields */
> +#define RISCV_IOMMU_PC_TA_V	BIT_ULL(0)
> +#define RISCV_IOMMU_PC_TA_ENS	BIT_ULL(1)
> +#define RISCV_IOMMU_PC_TA_SUM	BIT_ULL(2)
> +#define RISCV_IOMMU_PC_TA_PSCID	GENMASK_ULL(31, 12)
> +
> +/* First stage context fields */
> +#define RISCV_IOMMU_PC_FSC_PPN	RISCV_IOMMU_ATP_PPN_FIELD
> +#define RISCV_IOMMU_PC_FSC_MODE	RISCV_IOMMU_ATP_MODE_FIELD
> +
> +/*
> + * Chapter 3: In-memory queue interface
> + */
> +
> +/**
> + * struct riscv_iommu_command - Generic I/O MMU command structure
> + * @dword0: Includes the opcode and the function identifier
> + * @dword1: Opcode specific data
> + *
> + * The commands are interpreted as two 64bit fields, where the first
> + * 7bits of the first field are the opcode which also defines the
> + * command's format, followed by a 3bit field that specifies the
> + * function invoked by that command, and the rest is opcode-specific.
> + * This is a generic struct which will be populated differently
> + * according to each command. For more infos on the commands and
> + * the command queue check section 3.1.
> + */
> +struct riscv_iommu_command {
> +	u64 dword0;
> +	u64 dword1;
> +};
> +
> +/* Fields on dword0, common for all commands */
> +#define RISCV_IOMMU_CMD_OPCODE	GENMASK_ULL(6, 0)
> +#define	RISCV_IOMMU_CMD_FUNC	GENMASK_ULL(9, 7)
> +
> +/* 3.1.1 I/O MMU Page-table cache invalidation */
> +/* Fields on dword0 */
> +#define RISCV_IOMMU_CMD_IOTINVAL_OPCODE		1
> +#define RISCV_IOMMU_CMD_IOTINVAL_FUNC_VMA	0
> +#define RISCV_IOMMU_CMD_IOTINVAL_FUNC_GVMA	1
> +#define RISCV_IOMMU_CMD_IOTINVAL_AV		BIT_ULL(10)
> +#define RISCV_IOMMU_CMD_IOTINVAL_PSCID		GENMASK_ULL(31, 12)
> +#define RISCV_IOMMU_CMD_IOTINVAL_PSCV		BIT_ULL(32)
> +#define RISCV_IOMMU_CMD_IOTINVAL_GV		BIT_ULL(33)
> +#define RISCV_IOMMU_CMD_IOTINVAL_GSCID		GENMASK_ULL(59, 44)
> +/* dword1[61:10] is the 4K-aligned page address */
> +#define RISCV_IOMMU_CMD_IOTINVAL_ADDR		GENMASK_ULL(61, 10)
> +
> +/* 3.1.2 I/O MMU Command Queue Fences */
> +/* Fields on dword0 */
> +#define RISCV_IOMMU_CMD_IOFENCE_OPCODE		2
> +#define RISCV_IOMMU_CMD_IOFENCE_FUNC_C		0
> +#define RISCV_IOMMU_CMD_IOFENCE_AV		BIT_ULL(10)
> +#define RISCV_IOMMU_CMD_IOFENCE_WSI		BIT_ULL(11)
> +#define RISCV_IOMMU_CMD_IOFENCE_PR		BIT_ULL(12)
> +#define RISCV_IOMMU_CMD_IOFENCE_PW		BIT_ULL(13)
> +#define RISCV_IOMMU_CMD_IOFENCE_DATA		GENMASK_ULL(63, 32)
> +/* dword1 is the address, word-size aligned and shifted to the right by two bits. */
> +
> +/* 3.1.3 I/O MMU Directory cache invalidation */
> +/* Fields on dword0 */
> +#define RISCV_IOMMU_CMD_IODIR_OPCODE		3
> +#define RISCV_IOMMU_CMD_IODIR_FUNC_INVAL_DDT	0
> +#define RISCV_IOMMU_CMD_IODIR_FUNC_INVAL_PDT	1
> +#define RISCV_IOMMU_CMD_IODIR_PID		GENMASK_ULL(31, 12)
> +#define RISCV_IOMMU_CMD_IODIR_DV		BIT_ULL(33)
> +#define RISCV_IOMMU_CMD_IODIR_DID		GENMASK_ULL(63, 40)
> +/* dword1 is reserved for standard use */
> +
> +/* 3.1.4 I/O MMU PCIe ATS */
> +/* Fields on dword0 */
> +#define RISCV_IOMMU_CMD_ATS_OPCODE		4
> +#define RISCV_IOMMU_CMD_ATS_FUNC_INVAL		0
> +#define RISCV_IOMMU_CMD_ATS_FUNC_PRGR		1
> +#define RISCV_IOMMU_CMD_ATS_PID			GENMASK_ULL(31, 12)
> +#define RISCV_IOMMU_CMD_ATS_PV			BIT_ULL(32)
> +#define RISCV_IOMMU_CMD_ATS_DSV			BIT_ULL(33)
> +#define RISCV_IOMMU_CMD_ATS_RID			GENMASK_ULL(55, 40)
> +#define RISCV_IOMMU_CMD_ATS_DSEG		GENMASK_ULL(63, 56)
> +/* dword1 is the ATS payload, two different payload types for INVAL and PRGR */
> +
> +/* ATS.INVAL payload*/
> +#define RISCV_IOMMU_CMD_ATS_INVAL_G		BIT_ULL(0)
> +/* Bits 1 - 10 are zeroed */
> +#define RISCV_IOMMU_CMD_ATS_INVAL_S		BIT_ULL(11)
> +#define RISCV_IOMMU_CMD_ATS_INVAL_UADDR		GENMASK_ULL(63, 12)
> +
> +/* ATS.PRGR payload */
> +/* Bits 0 - 31 are zeroed */
> +#define RISCV_IOMMU_CMD_ATS_PRGR_PRG_INDEX	GENMASK_ULL(40, 32)
> +/* Bits 41 - 43 are zeroed */
> +#define RISCV_IOMMU_CMD_ATS_PRGR_RESP_CODE	GENMASK_ULL(47, 44)
> +#define RISCV_IOMMU_CMD_ATS_PRGR_DST_ID		GENMASK_ULL(63, 48)
> +
> +/**
> + * struct riscv_iommu_fq_record - Fault/Event Queue Record
> + * @hdr: Header, includes fault/event cause, PID/DID, transaction type etc
> + * @_reserved: Low 32bits for custom use, high 32bits for standard use
> + * @iotval: Transaction-type/cause specific format
> + * @iotval2: Cause specific format
> + *
> + * The fault/event queue reports events and failures raised when
> + * processing transactions. Each record is a 32byte structure where
> + * the first dword has a fixed format for providing generic infos
> + * regarding the fault/event, and two more dwords are there for
> + * fault/event-specific information. For more details see section
> + * 3.2.
> + */
> +struct riscv_iommu_fq_record {
> +	u64 hdr;
> +	u64 _reserved;
> +	u64 iotval;
> +	u64 iotval2;
> +};
> +
> +/* Fields on header */
> +#define RISCV_IOMMU_FQ_HDR_CAUSE	GENMASK_ULL(11, 0)
> +#define RISCV_IOMMU_FQ_HDR_PID		GENMASK_ULL(31, 12)
> +#define RISCV_IOMMU_FQ_HDR_PV		BIT_ULL(32)
> +#define RISCV_IOMMU_FQ_HDR_PRIV		BIT_ULL(33)
> +#define RISCV_IOMMU_FQ_HDR_TTYPE	GENMASK_ULL(39, 34)
> +#define RISCV_IOMMU_FQ_HDR_DID		GENMASK_ULL(63, 40)
> +
> +/**
> + * enum riscv_iommu_fq_causes - Fault/event cause values
> + * @RISCV_IOMMU_FQ_CAUSE_INST_FAULT: Instruction access fault
> + * @RISCV_IOMMU_FQ_CAUSE_RD_ADDR_MISALIGNED: Read address misaligned
> + * @RISCV_IOMMU_FQ_CAUSE_RD_FAULT: Read load fault
> + * @RISCV_IOMMU_FQ_CAUSE_WR_ADDR_MISALIGNED: Write/AMO address misaligned
> + * @RISCV_IOMMU_FQ_CAUSE_WR_FAULT: Write/AMO access fault
> + * @RISCV_IOMMU_FQ_CAUSE_INST_FAULT_S: Instruction page fault
> + * @RISCV_IOMMU_FQ_CAUSE_RD_FAULT_S: Read page fault
> + * @RISCV_IOMMU_FQ_CAUSE_WR_FAULT_S: Write/AMO page fault
> + * @RISCV_IOMMU_FQ_CAUSE_INST_FAULT_VS: Instruction guest page fault
> + * @RISCV_IOMMU_FQ_CAUSE_RD_FAULT_VS: Read guest page fault
> + * @RISCV_IOMMU_FQ_CAUSE_WR_FAULT_VS: Write/AMO guest page fault
> + * @RISCV_IOMMU_FQ_CAUSE_DMA_DISABLED: All inbound transactions disallowed
> + * @RISCV_IOMMU_FQ_CAUSE_DDT_LOAD_FAULT: DDT entry load access fault
> + * @RISCV_IOMMU_FQ_CAUSE_DDT_INVALID: DDT entry invalid
> + * @RISCV_IOMMU_FQ_CAUSE_DDT_MISCONFIGURED: DDT entry misconfigured
> + * @RISCV_IOMMU_FQ_CAUSE_TTYPE_BLOCKED: Transaction type disallowed
> + * @RISCV_IOMMU_FQ_CAUSE_MSI_LOAD_FAULT: MSI PTE load access fault
> + * @RISCV_IOMMU_FQ_CAUSE_MSI_INVALID: MSI PTE invalid
> + * @RISCV_IOMMU_FQ_CAUSE_MSI_MISCONFIGURED: MSI PTE misconfigured
> + * @RISCV_IOMMU_FQ_CAUSE_MRIF_FAULT: MRIF access fault
> + * @RISCV_IOMMU_FQ_CAUSE_PDT_LOAD_FAULT: PDT entry load access fault
> + * @RISCV_IOMMU_FQ_CAUSE_PDT_INVALID: PDT entry invalid
> + * @RISCV_IOMMU_FQ_CAUSE_PDT_MISCONFIGURED: PDT entry misconfigured
> + * @RISCV_IOMMU_FQ_CAUSE_DDT_CORRUPTED: DDT data corruption
> + * @RISCV_IOMMU_FQ_CAUSE_PDT_CORRUPTED: PDT data corruption
> + * @RISCV_IOMMU_FQ_CAUSE_MSI_PT_CORRUPTED: MSI page table data corruption
> + * @RISCV_IOMMU_FQ_CAUSE_MRIF_CORRUIPTED: MRIF data corruption
> + * @RISCV_IOMMU_FQ_CAUSE_INTERNAL_DP_ERROR: Internal data path error
> + * @RISCV_IOMMU_FQ_CAUSE_MSI_WR_FAULT: IOMMU MSI write access fault
> + * @RISCV_IOMMU_FQ_CAUSE_PT_CORRUPTED: First/second stage page table data corruption
> + *
> + * Values are on table 11 of the spec, encodings 275 - 2047 are reserved for standard
> + * use, and 2048 - 4095 for custom use.
> + */
> +enum riscv_iommu_fq_causes {
> +	RISCV_IOMMU_FQ_CAUSE_INST_FAULT = 1,
> +	RISCV_IOMMU_FQ_CAUSE_RD_ADDR_MISALIGNED = 4,
> +	RISCV_IOMMU_FQ_CAUSE_RD_FAULT = 5,
> +	RISCV_IOMMU_FQ_CAUSE_WR_ADDR_MISALIGNED = 6,
> +	RISCV_IOMMU_FQ_CAUSE_WR_FAULT = 7,
> +	RISCV_IOMMU_FQ_CAUSE_INST_FAULT_S = 12,
> +	RISCV_IOMMU_FQ_CAUSE_RD_FAULT_S = 13,
> +	RISCV_IOMMU_FQ_CAUSE_WR_FAULT_S = 15,
> +	RISCV_IOMMU_FQ_CAUSE_INST_FAULT_VS = 20,
> +	RISCV_IOMMU_FQ_CAUSE_RD_FAULT_VS = 21,
> +	RISCV_IOMMU_FQ_CAUSE_WR_FAULT_VS = 23,
> +	RISCV_IOMMU_FQ_CAUSE_DMA_DISABLED = 256,
> +	RISCV_IOMMU_FQ_CAUSE_DDT_LOAD_FAULT = 257,
> +	RISCV_IOMMU_FQ_CAUSE_DDT_INVALID = 258,
> +	RISCV_IOMMU_FQ_CAUSE_DDT_MISCONFIGURED = 259,
> +	RISCV_IOMMU_FQ_CAUSE_TTYPE_BLOCKED = 260,
> +	RISCV_IOMMU_FQ_CAUSE_MSI_LOAD_FAULT = 261,
> +	RISCV_IOMMU_FQ_CAUSE_MSI_INVALID = 262,
> +	RISCV_IOMMU_FQ_CAUSE_MSI_MISCONFIGURED = 263,
> +	RISCV_IOMMU_FQ_CAUSE_MRIF_FAULT = 264,
> +	RISCV_IOMMU_FQ_CAUSE_PDT_LOAD_FAULT = 265,
> +	RISCV_IOMMU_FQ_CAUSE_PDT_INVALID = 266,
> +	RISCV_IOMMU_FQ_CAUSE_PDT_MISCONFIGURED = 267,
> +	RISCV_IOMMU_FQ_CAUSE_DDT_CORRUPTED = 268,
> +	RISCV_IOMMU_FQ_CAUSE_PDT_CORRUPTED = 269,
> +	RISCV_IOMMU_FQ_CAUSE_MSI_PT_CORRUPTED = 270,
> +	RISCV_IOMMU_FQ_CAUSE_MRIF_CORRUIPTED = 271,
> +	RISCV_IOMMU_FQ_CAUSE_INTERNAL_DP_ERROR = 272,
> +	RISCV_IOMMU_FQ_CAUSE_MSI_WR_FAULT = 273,
> +	RISCV_IOMMU_FQ_CAUSE_PT_CORRUPTED = 274
> +};
> +
> +/**
> + * enum riscv_iommu_fq_ttypes: Fault/event transaction types
> + * @RISCV_IOMMU_FQ_TTYPE_NONE: None. Fault not caused by an inbound transaction.
> + * @RISCV_IOMMU_FQ_TTYPE_UADDR_INST_FETCH: Instruction fetch from untranslated address
> + * @RISCV_IOMMU_FQ_TTYPE_UADDR_RD: Read from untranslated address
> + * @RISCV_IOMMU_FQ_TTYPE_UADDR_WR: Write/AMO to untranslated address
> + * @RISCV_IOMMU_FQ_TTYPE_TADDR_INST_FETCH: Instruction fetch from translated address
> + * @RISCV_IOMMU_FQ_TTYPE_TADDR_RD: Read from translated address
> + * @RISCV_IOMMU_FQ_TTYPE_TADDR_WR: Write/AMO to translated address
> + * @RISCV_IOMMU_FQ_TTYPE_PCIE_ATS_REQ: PCIe ATS translation request
> + * @RISCV_IOMMU_FW_TTYPE_PCIE_MSG_REQ: PCIe message request
> + *
> + * Values are on table 12 of the spec, type 4 and 10 - 31 are reserved for standard use
> + * and 31 - 63 for custom use.
> + */
> +enum riscv_iommu_fq_ttypes {
> +	RISCV_IOMMU_FQ_TTYPE_NONE = 0,
> +	RISCV_IOMMU_FQ_TTYPE_UADDR_INST_FETCH = 1,
> +	RISCV_IOMMU_FQ_TTYPE_UADDR_RD = 2,
> +	RISCV_IOMMU_FQ_TTYPE_UADDR_WR = 3,
> +	RISCV_IOMMU_FQ_TTYPE_TADDR_INST_FETCH = 5,
> +	RISCV_IOMMU_FQ_TTYPE_TADDR_RD = 6,
> +	RISCV_IOMMU_FQ_TTYPE_TADDR_WR = 7,
> +	RISCV_IOMMU_FQ_TTYPE_PCIE_ATS_REQ = 8,
> +	RISCV_IOMMU_FW_TTYPE_PCIE_MSG_REQ = 9,
> +};
> +
> +/**
> + * struct riscv_iommu_pq_record - PCIe Page Request record
> + * @hdr: Header, includes PID, DID etc
> + * @payload: Holds the page address, request group and permission bits
> + *
> + * For more infos on the PCIe Page Request queue see chapter 3.3.
> + */
> +struct riscv_iommu_pq_record {
> +	u64 hdr;
> +	u64 payload;
> +};
> +
> +/* Header fields */
> +#define RISCV_IOMMU_PREQ_HDR_PID	GENMASK_ULL(31, 12)
> +#define RISCV_IOMMU_PREQ_HDR_PV		BIT_ULL(32)
> +#define RISCV_IOMMU_PREQ_HDR_PRIV	BIT_ULL(33)
> +#define RISCV_IOMMU_PREQ_HDR_EXEC	BIT_ULL(34)
> +#define RISCV_IOMMU_PREQ_HDR_DID	GENMASK_ULL(63, 40)
> +
> +/* Payload fields */
> +#define RISCV_IOMMU_PREQ_PAYLOAD_R	BIT_ULL(0)
> +#define RISCV_IOMMU_PREQ_PAYLOAD_W	BIT_ULL(1)
> +#define RISCV_IOMMU_PREQ_PAYLOAD_L	BIT_ULL(2)
> +#define RISCV_IOMMU_PREQ_PAYLOAD_M	GENMASK_ULL(2, 0)	/* Mask of RWL for convenience */
> +#define RISCV_IOMMU_PREQ_PRG_INDEX	GENMASK_ULL(11, 3)
> +#define RISCV_IOMMU_PREQ_UADDR		GENMASK_ULL(63, 12)
> +
> +/**
> + * struct riscv_iommu_msi_pte - MSI Page Table Entry
> + * @pte: MSI PTE
> + * @mrif_info: Memory-resident interrupt file info
> + *
> + * The MSI Page Table is used for virtualizing MSIs, so that when
> + * a device sends an MSI to a guest, the IOMMU can reroute it
> + * by translating the MSI address, either to a guest interrupt file
> + * or a memory resident interrupt file (MRIF). Note that this page table
> + * is an array of MSI PTEs, not a multi-level pt, each entry
> + * is a leaf entry. For more infos check out the AIA spec, chapter 9.5.
> + *
> + * Also in basic mode the mrif_info field is ignored by the IOMMU and can
> + * be used by software, any other reserved fields on pte must be zeroed-out
> + * by software.
> + */
> +struct riscv_iommu_msi_pte {
> +	u64 pte;
> +	u64 mrif_info;
> +};
> +
> +/* Fields on pte */
> +#define RISCV_IOMMU_MSI_PTE_V		BIT_ULL(0)
> +#define RISCV_IOMMU_MSI_PTE_M		GENMASK_ULL(2, 1)
> +#define RISCV_IOMMU_MSI_PTE_MRIF_ADDR	GENMASK_ULL(53, 7)	/* When M == 1 (MRIF mode) */
> +#define RISCV_IOMMU_MSI_PTE_PPN		RISCV_IOMMU_PPN_FIELD	/* When M == 3 (basic mode) */
> +#define RISCV_IOMMU_MSI_PTE_C		BIT_ULL(63)
> +
> +/* Fields on mrif_info */
> +#define RISCV_IOMMU_MSI_MRIF_NID	GENMASK_ULL(9, 0)
> +#define RISCV_IOMMU_MSI_MRIF_NPPN	RISCV_IOMMU_PPN_FIELD
> +#define RISCV_IOMMU_MSI_MRIF_NID_MSB	BIT_ULL(60)
> +
> +#endif /* _RISCV_IOMMU_BITS_H_ */
> diff --git a/drivers/iommu/riscv/iommu-platform.c b/drivers/iommu/riscv/iommu-platform.c
> new file mode 100644
> index 000000000000..770086ae2ab3
> --- /dev/null
> +++ b/drivers/iommu/riscv/iommu-platform.c
> @@ -0,0 +1,94 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * RISC-V IOMMU as a platform device
> + *
> + * Copyright © 2023 FORTH-ICS/CARV
> + * Copyright © 2023-2024 Rivos Inc.
> + *
> + * Authors
> + *	Nick Kossifidis <mick@ics.forth.gr>
> + *	Tomasz Jeznach <tjeznach@rivosinc.com>
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/of_platform.h>
> +#include <linux/platform_device.h>
> +
> +#include "iommu-bits.h"
> +#include "iommu.h"
> +
> +static int riscv_iommu_platform_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct riscv_iommu_device *iommu = NULL;
> +	struct resource *res = NULL;
> +	int vec;
> +
> +	iommu = devm_kzalloc(dev, sizeof(*iommu), GFP_KERNEL);
> +	if (!iommu)
> +		return -ENOMEM;
> +
> +	iommu->dev = dev;
> +	iommu->reg = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
> +	if (IS_ERR(iommu->reg))
> +		return dev_err_probe(dev, PTR_ERR(iommu->reg),
> +				     "could not map register region\n");
> +
> +	dev_set_drvdata(dev, iommu);
> +
> +	/* Check device reported capabilities / features. */
> +	iommu->caps = riscv_iommu_readq(iommu, RISCV_IOMMU_REG_CAP);
> +	iommu->fctl = riscv_iommu_readl(iommu, RISCV_IOMMU_REG_FCTL);
> +
> +	/* For now we only support WSI */
> +	switch (FIELD_GET(RISCV_IOMMU_CAP_IGS, iommu->caps)) {
> +	case RISCV_IOMMU_CAP_IGS_WSI:
> +	case RISCV_IOMMU_CAP_IGS_BOTH:
> +		break;
> +	default:
> +		return dev_err_probe(dev, -ENODEV,
> +				     "unable to use wire-signaled interrupts\n");
> +	}
> +
> +	iommu->irqs_count = platform_irq_count(pdev);
> +	if (iommu->irqs_count <= 0)
> +		return dev_err_probe(dev, -ENODEV,
> +				     "no IRQ resources provided\n");
> +
> +	for (vec = 0; vec < iommu->irqs_count; vec++)
> +		iommu->irqs[vec] = platform_get_irq(pdev, vec);

And if I've specified 97 interrupts in my DT because I won't let schema 
be the boss of me?

> +	/* Enable wire-signaled interrupts, fctl.WSI */
> +	if (!(iommu->fctl & RISCV_IOMMU_FCTL_WSI)) {
> +		iommu->fctl ^= RISCV_IOMMU_FCTL_WSI;

Using XOR to only ever set a 0 bit to 1 seems a bit obtuse.

> +		riscv_iommu_writel(iommu, RISCV_IOMMU_REG_FCTL, iommu->fctl);
> +	}
> +
> +	return riscv_iommu_init(iommu);
> +};
> +
> +static void riscv_iommu_platform_remove(struct platform_device *pdev)
> +{
> +	riscv_iommu_remove(dev_get_drvdata(&pdev->dev));
> +};
> +
> +static const struct of_device_id riscv_iommu_of_match[] = {
> +	{.compatible = "riscv,iommu",},
> +	{},
> +};
> +
> +MODULE_DEVICE_TABLE(of, riscv_iommu_of_match);

And yet it cannot be a module?

> +static struct platform_driver riscv_iommu_platform_driver = {
> +	.probe = riscv_iommu_platform_probe,
> +	.remove_new = riscv_iommu_platform_remove,
> +	.driver = {
> +		.name = "riscv,iommu",
> +		.of_match_table = riscv_iommu_of_match,
> +		.suppress_bind_attrs = true,
> +	},
> +};
> +
> +module_driver(riscv_iommu_platform_driver, platform_driver_register,
> +	      platform_driver_unregister);

module_platform_driver() is a thing. Or builtin_platform_driver(), as 
things currently stand.

> diff --git a/drivers/iommu/riscv/iommu.c b/drivers/iommu/riscv/iommu.c
> new file mode 100644
> index 000000000000..af68c89200a9
> --- /dev/null
> +++ b/drivers/iommu/riscv/iommu.c
> @@ -0,0 +1,89 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * IOMMU API for RISC-V IOMMU implementations.
> + *
> + * Copyright © 2022-2024 Rivos Inc.
> + * Copyright © 2023 FORTH-ICS/CARV
> + *
> + * Authors
> + *	Tomasz Jeznach <tjeznach@rivosinc.com>
> + *	Nick Kossifidis <mick@ics.forth.gr>
> + */
> +
> +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

I guess that ends up as "iommu:"? Given that that prefix already belongs 
to the core code, please pick something more specific.

> +#include <linux/compiler.h>
> +#include <linux/dma-mapping.h>
> +#include <linux/init.h>
> +#include <linux/iommu.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +
> +#include "iommu-bits.h"
> +#include "iommu.h"
> +
> +MODULE_DESCRIPTION("Driver for RISC-V IOMMU");
> +MODULE_AUTHOR("Tomasz Jeznach <tjeznach@rivosinc.com>");
> +MODULE_AUTHOR("Nick Kossifidis <mick@ics.forth.gr>");
> +MODULE_LICENSE("GPL");
> +
> +/* Timeouts in [us] */
> +#define RISCV_IOMMU_DDTP_TIMEOUT	50000
> +
> +static int riscv_iommu_init_check(struct riscv_iommu_device *iommu)
> +{
> +	u64 ddtp;
> +
> +	/* Hardware must be configured in OFF | BARE mode at system initialization. */
> +	riscv_iommu_readq_timeout(iommu, RISCV_IOMMU_REG_DDTP,
> +				  ddtp, !(ddtp & RISCV_IOMMU_DDTP_BUSY),
> +				  10, RISCV_IOMMU_DDTP_TIMEOUT);
> +	if (FIELD_GET(RISCV_IOMMU_DDTP_MODE, ddtp) > RISCV_IOMMU_DDTP_MODE_BARE)
> +		return -EBUSY;

It looks like RISC-V already supports kdump, so you probably want to be 
prepared to find the IOMMU with its pants down and deal with it from day 
one.

> +
> +	/* Configure accesses to in-memory data structures for CPU-native byte order. */
> +	if (IS_ENABLED(CONFIG_CPU_BIG_ENDIAN) != !!(iommu->fctl & RISCV_IOMMU_FCTL_BE)) {
> +		if (!(iommu->caps & RISCV_IOMMU_CAP_END))
> +			return -EINVAL;
> +		riscv_iommu_writel(iommu, RISCV_IOMMU_REG_FCTL,
> +				   iommu->fctl ^ RISCV_IOMMU_FCTL_BE);
> +		iommu->fctl = riscv_iommu_readl(iommu, RISCV_IOMMU_REG_FCTL);
> +		if (IS_ENABLED(CONFIG_CPU_BIG_ENDIAN) != !!(iommu->fctl & RISCV_IOMMU_FCTL_BE))
> +			return -EINVAL;
> +	}

That's fun. It could be reorganised to avoid the duplicate check, but it 
is rather majestic as-is :)

> +
> +	dma_set_mask_and_coherent(iommu->dev,
> +				  DMA_BIT_MASK(FIELD_GET(RISCV_IOMMU_CAP_PAS, iommu->caps)));

This isn't a check, so I would think it belongs to "_init" rather than 
"_init_check".

Thanks,
Robin.

> +
> +	return 0;
> +}
> +
> +void riscv_iommu_remove(struct riscv_iommu_device *iommu)
> +{
> +	iommu_device_sysfs_remove(&iommu->iommu);
> +}
> +
> +int riscv_iommu_init(struct riscv_iommu_device *iommu)
> +{
> +	int rc;
> +
> +	rc = riscv_iommu_init_check(iommu);
> +	if (rc)
> +		return dev_err_probe(iommu->dev, rc, "unexpected device state\n");
> +	/*
> +	 * Placeholder for a complete IOMMU device initialization.
> +	 * For now, only bare minimum: enable global identity mapping mode and register sysfs.
> +	 */
> +	riscv_iommu_writeq(iommu, RISCV_IOMMU_REG_DDTP,
> +			   FIELD_PREP(RISCV_IOMMU_DDTP_MODE, RISCV_IOMMU_DDTP_MODE_BARE));
> +
> +	rc = iommu_device_sysfs_add(&iommu->iommu, NULL, NULL, "riscv-iommu@%s",
> +				    dev_name(iommu->dev));
> +	if (WARN(rc, "cannot register sysfs interface\n"))
> +		goto err_sysfs;
> +
> +	return 0;
> +
> +err_sysfs:
> +	return rc;
> +}
> diff --git a/drivers/iommu/riscv/iommu.h b/drivers/iommu/riscv/iommu.h
> new file mode 100644
> index 000000000000..700e33dc2446
> --- /dev/null
> +++ b/drivers/iommu/riscv/iommu.h
> @@ -0,0 +1,62 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * Copyright © 2022-2024 Rivos Inc.
> + * Copyright © 2023 FORTH-ICS/CARV
> + *
> + * Authors
> + *	Tomasz Jeznach <tjeznach@rivosinc.com>
> + *	Nick Kossifidis <mick@ics.forth.gr>
> + */
> +
> +#ifndef _RISCV_IOMMU_H_
> +#define _RISCV_IOMMU_H_
> +
> +#include <linux/iommu.h>
> +#include <linux/types.h>
> +#include <linux/iopoll.h>
> +
> +#include "iommu-bits.h"
> +
> +struct riscv_iommu_device {
> +	/* iommu core interface */
> +	struct iommu_device iommu;
> +
> +	/* iommu hardware */
> +	struct device *dev;
> +
> +	/* hardware control register space */
> +	void __iomem *reg;
> +
> +	/* supported and enabled hardware capabilities */
> +	u64 caps;
> +	u32 fctl;
> +
> +	/* available interrupt numbers, MSI or WSI */
> +	unsigned int irqs[RISCV_IOMMU_INTR_COUNT];
> +	unsigned int irqs_count;
> +};
> +
> +int riscv_iommu_init(struct riscv_iommu_device *iommu);
> +void riscv_iommu_remove(struct riscv_iommu_device *iommu);
> +
> +#define riscv_iommu_readl(iommu, addr) \
> +	readl_relaxed((iommu)->reg + (addr))
> +
> +#define riscv_iommu_readq(iommu, addr) \
> +	readq_relaxed((iommu)->reg + (addr))
> +
> +#define riscv_iommu_writel(iommu, addr, val) \
> +	writel_relaxed((val), (iommu)->reg + (addr))
> +
> +#define riscv_iommu_writeq(iommu, addr, val) \
> +	writeq_relaxed((val), (iommu)->reg + (addr))
> +
> +#define riscv_iommu_readq_timeout(iommu, addr, val, cond, delay_us, timeout_us) \
> +	readx_poll_timeout(readq_relaxed, (iommu)->reg + (addr), val, cond, \
> +			   delay_us, timeout_us)
> +
> +#define riscv_iommu_readl_timeout(iommu, addr, val, cond, delay_us, timeout_us) \
> +	readx_poll_timeout(readl_relaxed, (iommu)->reg + (addr), val, cond, \
> +			   delay_us, timeout_us)
> +
> +#endif