iommu.lists.linux-foundation.org archive mirror
 help / color / mirror / Atom feed
From: Jean-Philippe Brucker <jean-philippe@linaro.org>
To: will@kernel.org, mark.rutland@arm.com
Cc: Jean-Philippe Brucker <jean-philippe@linaro.org>,
	iommu@lists.linux-foundation.org, robin.murphy@arm.com,
	linux-arm-kernel@lists.infradead.org
Subject: [PATCH] perf/smmuv3: Allow sharing MMIO registers with the SMMU driver
Date: Tue, 21 Apr 2020 17:57:46 +0200	[thread overview]
Message-ID: <20200421155745.19815-1-jean-philippe@linaro.org> (raw)

Some Arm SMMUv3 implementations, for example Arm CoreLink MMU-600, embed
the PMCG registers into the SMMU MMIO regions. It currently causes probe
failure because the PMU and SMMU drivers request overlapping resources.

Avoid the conflict by calling devm_ioremap() directly from the PMU
driver. We loose some sanity-checking of the memory map provided by
firmware, which doesn't seem catastrophic.

Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
---

So this is the simplest solution, and I don't think we're missing much
by skipping the resource reservation. I've also been exploring a more
complex approach [1] which has the SMMU driver perform resource
reservation on behalf of the PMU driver, but I'm not sure it's
necessary.

Please test, I've only tried the RevC FastModel using devicetree so far.

[1] https://jpbrucker.net/git/linux/log/?h=smmu/pmu
---
 drivers/perf/arm_smmuv3_pmu.c | 28 +++++++++++++++++++++-------
 1 file changed, 21 insertions(+), 7 deletions(-)

diff --git a/drivers/perf/arm_smmuv3_pmu.c b/drivers/perf/arm_smmuv3_pmu.c
index ca183a53a7f10..ad63d1e73333f 100644
--- a/drivers/perf/arm_smmuv3_pmu.c
+++ b/drivers/perf/arm_smmuv3_pmu.c
@@ -730,8 +730,8 @@ static void smmu_pmu_get_acpi_options(struct smmu_pmu *smmu_pmu)
 
 static int smmu_pmu_probe(struct platform_device *pdev)
 {
+	struct resource *res_0, *res_1;
 	struct smmu_pmu *smmu_pmu;
-	struct resource *res_0;
 	u32 cfgr, reg_size;
 	u64 ceid_64[2];
 	int irq, err;
@@ -759,18 +759,32 @@ static int smmu_pmu_probe(struct platform_device *pdev)
 		.capabilities	= PERF_PMU_CAP_NO_EXCLUDE,
 	};
 
+	/*
+	 * If the PMCG registers are embedded into the SMMU regions, the
+	 * resources have to be shared with the SMMU driver. Use ioremap()
+	 * rather than ioremap_resource() to avoid conflicts.
+	 */
 	res_0 = platform_get_resource(pdev, IORESOURCE_MEM, 0);
-	smmu_pmu->reg_base = devm_ioremap_resource(dev, res_0);
-	if (IS_ERR(smmu_pmu->reg_base))
-		return PTR_ERR(smmu_pmu->reg_base);
+	if (!res_0)
+		return -ENXIO;
+
+	smmu_pmu->reg_base = devm_ioremap(dev, res_0->start,
+					  resource_size(res_0));
+	if (!smmu_pmu->reg_base)
+		return -ENOMEM;
 
 	cfgr = readl_relaxed(smmu_pmu->reg_base + SMMU_PMCG_CFGR);
 
 	/* Determine if page 1 is present */
 	if (cfgr & SMMU_PMCG_CFGR_RELOC_CTRS) {
-		smmu_pmu->reloc_base = devm_platform_ioremap_resource(pdev, 1);
-		if (IS_ERR(smmu_pmu->reloc_base))
-			return PTR_ERR(smmu_pmu->reloc_base);
+		res_1 = platform_get_resource(pdev, IORESOURCE_MEM, 1);
+		if (!res_1)
+			return -ENXIO;
+
+		smmu_pmu->reloc_base = devm_ioremap(dev, res_1->start,
+						    resource_size(res_1));
+		if (!smmu_pmu->reloc_base)
+			return -ENOMEM;
 	} else {
 		smmu_pmu->reloc_base = smmu_pmu->reg_base;
 	}
-- 
2.26.0

_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu

             reply	other threads:[~2020-04-21 16:09 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-21 15:57 Jean-Philippe Brucker [this message]
2020-04-21 17:25 ` [PATCH] perf/smmuv3: Allow sharing MMIO registers with the SMMU driver Robin Murphy
2020-04-28 18:10 ` Tuan Phan
2020-04-29  7:21   ` Jean-Philippe Brucker
2020-04-29 18:01     ` Tuan Phan
2020-05-06 16:11       ` Jean-Philippe Brucker
2020-05-20 12:24 ` Will Deacon
2020-05-20 12:44   ` Jean-Philippe Brucker

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20200421155745.19815-1-jean-philippe@linaro.org \
    --to=jean-philippe@linaro.org \
    --cc=iommu@lists.linux-foundation.org \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=mark.rutland@arm.com \
    --cc=robin.murphy@arm.com \
    --cc=will@kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).