linux-kernel - [PATCH 4/7] dma-mapping: Add helpers for dma_range

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Message-Id: <b6626985d97ddc33a23b4b9fafa881b35001547e.1701268753.git.robin.murphy@arm.com>
Date:   Wed, 29 Nov 2023 17:43:01 +0000
From:   Robin Murphy <robin.murphy@....com>
To:     Joerg Roedel <joro@...tes.org>, Christoph Hellwig <hch@....de>
Cc:     Vineet Gupta <vgupta@...nel.org>,
        Russell King <linux@...linux.org.uk>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Huacai Chen <chenhuacai@...nel.org>,
        WANG Xuerui <kernel@...0n.name>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Lorenzo Pieralisi <lpieralisi@...nel.org>,
        Hanjun Guo <guohanjun@...wei.com>,
        Sudeep Holla <sudeep.holla@....com>,
        "K. Y. Srinivasan" <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        Wei Liu <wei.liu@...nel.org>, Dexuan Cui <decui@...rosoft.com>,
        Suravee Suthikulpanit <suravee.suthikulpanit@....com>,
        David Woodhouse <dwmw2@...radead.org>,
        Lu Baolu <baolu.lu@...ux.intel.com>,
        Niklas Schnelle <schnelle@...ux.ibm.com>,
        Matthew Rosato <mjrosato@...ux.ibm.com>,
        Gerald Schaefer <gerald.schaefer@...ux.ibm.com>,
        Jean-Philippe Brucker <jean-philippe@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Jason Gunthorpe <jgg@...pe.ca>, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-acpi@...r.kernel.org,
        iommu@...ts.linux.dev, devicetree@...r.kernel.org
Subject: [PATCH 4/7] dma-mapping: Add helpers for dma_range_map bounds

Several places want to compute the lower and/or upper bounds of a
dma_range_map, so let's factor that out into reusable helpers.

Signed-off-by: Robin Murphy <robin.murphy@....com>
---
 arch/loongarch/kernel/dma.c |  9 ++-------
 drivers/acpi/arm64/dma.c    |  8 +-------
 drivers/of/device.c         | 11 ++---------
 include/linux/dma-direct.h  | 18 ++++++++++++++++++
 4 files changed, 23 insertions(+), 23 deletions(-)

diff --git a/arch/loongarch/kernel/dma.c b/arch/loongarch/kernel/dma.c
index 7a9c6a9dd2d0..429555fb4e13 100644
--- a/arch/loongarch/kernel/dma.c
+++ b/arch/loongarch/kernel/dma.c
@@ -8,17 +8,12 @@
 void acpi_arch_dma_setup(struct device *dev)
 {
 	int ret;
-	u64 mask, end = 0;
+	u64 mask, end;
 	const struct bus_dma_region *map = NULL;
 
 	ret = acpi_dma_get_range(dev, &map);
 	if (!ret && map) {
-		const struct bus_dma_region *r = map;
-
-		for (end = 0; r->size; r++) {
-			if (r->dma_start + r->size - 1 > end)
-				end = r->dma_start + r->size - 1;
-		}
+		end = dma_range_map_max(map);
 
 		mask = DMA_BIT_MASK(ilog2(end) + 1);
 		dev->bus_dma_limit = end;
diff --git a/drivers/acpi/arm64/dma.c b/drivers/acpi/arm64/dma.c
index b98a149f8d50..52b2abf88689 100644
--- a/drivers/acpi/arm64/dma.c
+++ b/drivers/acpi/arm64/dma.c
@@ -28,13 +28,7 @@ void acpi_arch_dma_setup(struct device *dev)
 
 	ret = acpi_dma_get_range(dev, &map);
 	if (!ret && map) {
-		const struct bus_dma_region *r = map;
-
-		for (end = 0; r->size; r++) {
-			if (r->dma_start + r->size - 1 > end)
-				end = r->dma_start + r->size - 1;
-		}
-
+		end = dma_range_map_max(map);
 		dev->dma_range_map = map;
 	}
 
diff --git a/drivers/of/device.c b/drivers/of/device.c
index 51062a831970..66879edb4a61 100644
--- a/drivers/of/device.c
+++ b/drivers/of/device.c
@@ -117,16 +117,9 @@ int of_dma_configure_id(struct device *dev, struct device_node *np,
 		if (!force_dma)
 			return ret == -ENODEV ? 0 : ret;
 	} else {
-		const struct bus_dma_region *r = map;
-
 		/* Determine the overall bounds of all DMA regions */
-		for (dma_start = ~0; r->size; r++) {
-			/* Take lower and upper limits */
-			if (r->dma_start < dma_start)
-				dma_start = r->dma_start;
-			if (r->dma_start + r->size > end)
-				end = r->dma_start + r->size;
-		}
+		dma_start = dma_range_map_min(map);
+		end = dma_range_map_max(map);
 	}
 
 	/*
diff --git a/include/linux/dma-direct.h b/include/linux/dma-direct.h
index 3eb3589ff43e..b77e3863daab 100644
--- a/include/linux/dma-direct.h
+++ b/include/linux/dma-direct.h
@@ -54,6 +54,24 @@ static inline phys_addr_t translate_dma_to_phys(struct device *dev,
 	return (phys_addr_t)-1;
 }
 
+static inline dma_addr_t dma_range_map_min(const struct bus_dma_region *map)
+{
+	dma_addr_t ret = U64_MAX;
+
+	for (; map->size; map++)
+		ret = min(ret, map->dma_start);
+	return ret;
+}
+
+static inline dma_addr_t dma_range_map_max(const struct bus_dma_region *map)
+{
+	dma_addr_t ret = 0;
+
+	for (; map->size; map++)
+		ret = max(ret, map->dma_start + map->size - 1);
+	return ret;
+}
+
 #ifdef CONFIG_ARCH_HAS_PHYS_TO_DMA
 #include <asm/dma-direct.h>
 #ifndef phys_to_dma_unencrypted
-- 
2.39.2.101.g768bb238c484.dirty