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From: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
To: linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org
Cc: f.fainelli@gmail.com, arnd@arndb.de, narmstrong@baylibre.com,
	dwmw2@infradead.org, linux@armlinux.org.uk, hch@infradead.org,
	will@kernel.org, robh+dt@kernel.org, catalin.marinas@arm.com,
	robin.murphy@arm.com, ardb@kernel.org,
	Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Subject: [RFC 09/13] iommu/arm-smmu: Make use of dev_64bit_mmio_supported()
Date: Fri, 26 Feb 2021 15:03:01 +0100
Message-ID: <20210226140305.26356-10-nsaenzjulienne@suse.de> (raw)
In-Reply-To: <20210226140305.26356-1-nsaenzjulienne@suse.de>

Some arm SMMU implementations might sit on a bus that doesn't support
64bit memory accesses. In that case default to using hi_lo_{readq,
writeq}() and BUG if such platform tries to use AArch64 formats as they
rely on writeq()'s atomicity.

Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
---
 drivers/iommu/arm/arm-smmu/arm-smmu.c | 9 +++++++++
 drivers/iommu/arm/arm-smmu/arm-smmu.h | 9 +++++++--
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.c b/drivers/iommu/arm/arm-smmu/arm-smmu.c
index d8c6bfde6a61..239ff42b20c3 100644
--- a/drivers/iommu/arm/arm-smmu/arm-smmu.c
+++ b/drivers/iommu/arm/arm-smmu/arm-smmu.c
@@ -1889,6 +1889,15 @@ static int arm_smmu_device_cfg_probe(struct arm_smmu_device *smmu)
 			smmu->features |= ARM_SMMU_FEAT_FMT_AARCH64_64K;
 	}
 
+	/*
+	 * 64bit accesses not possible through the interconnect, AArch64
+	 * formats depend on it.
+	 */
+	BUG_ON(!dev_64bit_mmio_supported(smmu->dev) &&
+	       smmu->features & (ARM_SMMU_FEAT_FMT_AARCH64_4K |
+				ARM_SMMU_FEAT_FMT_AARCH64_16K |
+				ARM_SMMU_FEAT_FMT_AARCH64_64K));
+
 	if (smmu->impl && smmu->impl->cfg_probe) {
 		ret = smmu->impl->cfg_probe(smmu);
 		if (ret)
diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.h b/drivers/iommu/arm/arm-smmu/arm-smmu.h
index d2a2d1bc58ba..997d13a21717 100644
--- a/drivers/iommu/arm/arm-smmu/arm-smmu.h
+++ b/drivers/iommu/arm/arm-smmu/arm-smmu.h
@@ -477,15 +477,20 @@ static inline void arm_smmu_writel(struct arm_smmu_device *smmu, int page,
 {
 	if (smmu->impl && unlikely(smmu->impl->write_reg))
 		smmu->impl->write_reg(smmu, page, offset, val);
-	else
+	else if (dev_64bit_mmio_supported(smmu->dev))
 		writel_relaxed(val, arm_smmu_page(smmu, page) + offset);
+	else
+		hi_lo_writeq_relaxed(val, arm_smmu_page(smmu, page) + offset);
 }
 
 static inline u64 arm_smmu_readq(struct arm_smmu_device *smmu, int page, int offset)
 {
 	if (smmu->impl && unlikely(smmu->impl->read_reg64))
 		return smmu->impl->read_reg64(smmu, page, offset);
-	return readq_relaxed(arm_smmu_page(smmu, page) + offset);
+	else if (dev_64bit_mmio_supported(smmu->dev))
+		return readq_relaxed(arm_smmu_page(smmu, page) + offset);
+	else
+		return hi_lo_readq_relaxed(arm_smmu_page(smmu, page) + offset);
 }
 
 static inline void arm_smmu_writeq(struct arm_smmu_device *smmu, int page,
-- 
2.30.1


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  parent reply index

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-26 14:02 [RFC 00/13] Generic way of dealing with broken 64-bit buses Nicolas Saenz Julienne
2021-02-26 14:02 ` [RFC 01/13] dt-bindings: Introduce 64bit-mmio-broken Nicolas Saenz Julienne
2021-02-26 14:02 ` [RFC 02/13] driver core: Introduce MMIO configuration Nicolas Saenz Julienne
2021-03-02 11:29   ` Robin Murphy
2021-03-02 14:09     ` Nicolas Saenz Julienne
2021-02-26 14:02 ` [RFC 03/13] of: device: Introduce of_mmio_configure() Nicolas Saenz Julienne
2021-02-26 14:02 ` [RFC 04/13] driver core: plafrom: Introduce platform_mmio_configure() Nicolas Saenz Julienne
2021-02-26 14:02 ` [RFC 05/13] pci: Introduce pci_mmio_configure() Nicolas Saenz Julienne
2021-02-26 14:02 ` [RFC 06/13] device core: Introduce dev_64bit_mmio_supported() Nicolas Saenz Julienne
2021-02-26 14:02 ` [RFC 07/13] arm64: Mark ARCH_MVEBU as needing broken 64bit MMIO support Nicolas Saenz Julienne
2021-02-26 14:03 ` [RFC 08/13] arm64: dts: marvell: armada-ap80x: Mark config-space bus as 64bit-mmio-broken Nicolas Saenz Julienne
2021-02-26 14:03 ` Nicolas Saenz Julienne [this message]
2021-03-02  9:32   ` [RFC 09/13] iommu/arm-smmu: Make use of dev_64bit_mmio_supported() Arnd Bergmann
2021-03-02 12:42     ` Nicolas Saenz Julienne
2021-03-02 11:07   ` Robin Murphy
2021-03-02 13:38     ` Nicolas Saenz Julienne
2021-03-03  8:44     ` Arnd Bergmann
2021-02-26 14:03 ` [RFC 10/13] iommu/arm-smmu-impl: Get rid of Marvell's implementation details Nicolas Saenz Julienne
2021-03-02 11:40   ` Robin Murphy
2021-03-02 14:06     ` Nicolas Saenz Julienne
2021-02-26 14:03 ` [RFC 11/13] arm64: Mark ARCH_BCM2835 as needing broken 64bit MMIO support Nicolas Saenz Julienne
2021-02-26 14:03 ` [RFC 12/13] ARM: dts: bcm2711: Mark PCIe bus as 64bit-mmio-broken Nicolas Saenz Julienne
2021-02-26 14:03 ` [RFC 13/13] scsi: megaraid: Make use of dev_64bit_mmio_supported() Nicolas Saenz Julienne
2021-02-26 14:30   ` Arnd Bergmann
2021-02-26 18:06     ` Arnd Bergmann

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