linux-kernel - [PATCH 1/2] perf/smmuv3: Don't reserve the register space that overlaps with the SMMUv3

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Message-ID: <20210119015951.1042-2-thunder.leizhen@huawei.com>
Date:   Tue, 19 Jan 2021 09:59:50 +0800
From:   Zhen Lei <thunder.leizhen@...wei.com>
To:     Will Deacon <will@...nel.org>, Robin Murphy <robin.murphy@....com>,
        "Mark Rutland" <mark.rutland@....com>,
        Joerg Roedel <joro@...tes.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        iommu <iommu@...ts.linux-foundation.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
CC:     Zhen Lei <thunder.leizhen@...wei.com>,
        Jean-Philippe Brucker <jean-philippe@...aro.org>,
        Neil Leeder <nleeder@...eaurora.org>,
        "Shameer Kolothum" <shameerali.kolothum.thodi@...wei.com>
Subject: [PATCH 1/2] perf/smmuv3: Don't reserve the register space that overlaps with the SMMUv3

Some SMMUv3 implementation embed the Perf Monitor Group Registers (PMCG)
inside the first 64kB region of the SMMU. Since SMMU and PMCG are managed
by two separate drivers, and this driver depends on ARM_SMMU_V3, so the
SMMU driver reserves the corresponding resource first, this driver should
not reserve the corresponding resource again. Otherwise, a resource
reservation conflict is reported during boot.

Signed-off-by: Zhen Lei <thunder.leizhen@...wei.com>
---
 drivers/perf/arm_smmuv3_pmu.c | 42 ++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 40 insertions(+), 2 deletions(-)

diff --git a/drivers/perf/arm_smmuv3_pmu.c b/drivers/perf/arm_smmuv3_pmu.c
index 74474bb322c3f26..dcce085431c6ce8 100644
--- a/drivers/perf/arm_smmuv3_pmu.c
+++ b/drivers/perf/arm_smmuv3_pmu.c
@@ -761,6 +761,44 @@ static void smmu_pmu_get_acpi_options(struct smmu_pmu *smmu_pmu)
 	dev_notice(smmu_pmu->dev, "option mask 0x%x\n", smmu_pmu->options);
 }
 
+static void __iomem *
+smmu_pmu_get_and_ioremap_resource(struct platform_device *pdev,
+				  unsigned int index,
+				  struct resource **out_res)
+{
+	int ret;
+	void __iomem *base;
+	struct resource *res;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, index);
+	if (!res) {
+		dev_err(&pdev->dev, "invalid resource\n");
+		return IOMEM_ERR_PTR(-EINVAL);
+	}
+	if (out_res)
+		*out_res = res;
+
+	ret = region_intersects(res->start, resource_size(res),
+				IORESOURCE_MEM, IORES_DESC_NONE);
+	if (ret == REGION_INTERSECTS) {
+		/*
+		 * The resource has already been reserved by the SMMUv3 driver.
+		 * Don't reserve it again, just do devm_ioremap().
+		 */
+		base = devm_ioremap(&pdev->dev, res->start, resource_size(res));
+	} else {
+		/*
+		 * The resource may have not been reserved by any driver, or
+		 * has been reserved but not type IORESOURCE_MEM. In the latter
+		 * case, devm_ioremap_resource() reports a conflict and returns
+		 * IOMEM_ERR_PTR(-EBUSY).
+		 */
+		base = devm_ioremap_resource(&pdev->dev, res);
+	}
+
+	return base;
+}
+
 static int smmu_pmu_probe(struct platform_device *pdev)
 {
 	struct smmu_pmu *smmu_pmu;
@@ -793,7 +831,7 @@ static int smmu_pmu_probe(struct platform_device *pdev)
 		.capabilities	= PERF_PMU_CAP_NO_EXCLUDE,
 	};
 
-	smmu_pmu->reg_base = devm_platform_get_and_ioremap_resource(pdev, 0, &res_0);
+	smmu_pmu->reg_base = smmu_pmu_get_and_ioremap_resource(pdev, 0, &res_0);
 	if (IS_ERR(smmu_pmu->reg_base))
 		return PTR_ERR(smmu_pmu->reg_base);
 
@@ -801,7 +839,7 @@ static int smmu_pmu_probe(struct platform_device *pdev)
 
 	/* Determine if page 1 is present */
 	if (cfgr & SMMU_PMCG_CFGR_RELOC_CTRS) {
-		smmu_pmu->reloc_base = devm_platform_ioremap_resource(pdev, 1);
+		smmu_pmu->reloc_base = smmu_pmu_get_and_ioremap_resource(pdev, 1, NULL);
 		if (IS_ERR(smmu_pmu->reloc_base))
 			return PTR_ERR(smmu_pmu->reloc_base);
 	} else {
-- 
1.8.3