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Date: Fri, 9 Jun 2017 11:28:59 +0100
From: Robin Murphy <robin.murphy@....com>
To: Geetha sowjanya <gakula@...iumnetworks.com>, will.deacon@....com,
lorenzo.pieralisi@....com, hanjun.guo@...aro.org,
sudeep.holla@....com, iommu@...ts.linux-foundation.org
Cc: robert.moore@...el.com, lv.zheng@...el.com, rjw@...ysocki.net,
jcm@...hat.com, linux-kernel@...r.kernel.org,
robert.richter@...ium.com, catalin.marinas@....com,
sgoutham@...ium.com, linux-arm-kernel@...ts.infradead.org,
linux-acpi@...r.kernel.org, geethasowjanya.akula@...il.com,
devel@...ica.org, linu.cherian@...ium.com,
Charles.Garcia-Tobin@....com, robh@...nel.org,
Geetha Sowjanya <geethasowjanya.akula@...ium.com>
Subject: Re: [PATCH v7 2/3] iommu/arm-smmu-v3: Add workaround for Cavium
ThunderX2 erratum #74
On 30/05/17 13:03, Geetha sowjanya wrote:
> From: Linu Cherian <linu.cherian@...ium.com>
>
> Cavium ThunderX2 SMMU implementation doesn't support page 1 register space
> and PAGE0_REGS_ONLY option is enabled as an errata workaround.
> This option when turned on, replaces all page 1 offsets used for
> EVTQ_PROD/CONS, PRIQ_PROD/CONS register access with page 0 offsets.
>
> SMMU resource size checks are now based on SMMU option PAGE0_REGS_ONLY,
> since resource size can be either 64k/128k.
> For this, arm_smmu_device_dt_probe/acpi_probe has been moved before
> platform_get_resource call, so that SMMU options are set beforehand.
>
> Signed-off-by: Linu Cherian <linu.cherian@...ium.com>
> Signed-off-by: Geetha Sowjanya <geethasowjanya.akula@...ium.com>
> ---
> Documentation/arm64/silicon-errata.txt | 1 +
> .../devicetree/bindings/iommu/arm,smmu-v3.txt | 6 ++
> drivers/iommu/arm-smmu-v3.c | 64 +++++++++++++++-----
> 3 files changed, 56 insertions(+), 15 deletions(-)
>
> diff --git a/Documentation/arm64/silicon-errata.txt b/Documentation/arm64/silicon-errata.txt
> index 10f2ddd..4693a32 100644
> --- a/Documentation/arm64/silicon-errata.txt
> +++ b/Documentation/arm64/silicon-errata.txt
> @@ -62,6 +62,7 @@ stable kernels.
> | Cavium | ThunderX GICv3 | #23154 | CAVIUM_ERRATUM_23154 |
> | Cavium | ThunderX Core | #27456 | CAVIUM_ERRATUM_27456 |
> | Cavium | ThunderX SMMUv2 | #27704 | N/A |
> +| Cavium | ThunderX2 SMMUv3| #74 | N/A |
> | | | | |
> | Freescale/NXP | LS2080A/LS1043A | A-008585 | FSL_ERRATUM_A008585 |
> | | | | |
> diff --git a/Documentation/devicetree/bindings/iommu/arm,smmu-v3.txt b/Documentation/devicetree/bindings/iommu/arm,smmu-v3.txt
> index be57550..607e270 100644
> --- a/Documentation/devicetree/bindings/iommu/arm,smmu-v3.txt
> +++ b/Documentation/devicetree/bindings/iommu/arm,smmu-v3.txt
> @@ -49,6 +49,12 @@ the PCIe specification.
> - hisilicon,broken-prefetch-cmd
> : Avoid sending CMD_PREFETCH_* commands to the SMMU.
>
> +- cavium,cn9900-broken-page1-regspace
> + : Replaces all page 1 offsets used for EVTQ_PROD/CONS,
> + PRIQ_PROD/CONS register access with page 0 offsets.
> + Set for Caviun ThunderX2 silicon that doesn't support
> + SMMU page1 register space.
The indentation's a bit funky here - the rest of this file is actually
indented with spaces, but either way it's clear your editor isn't set to
8-space tabs ;)
> +
> ** Example
>
> smmu@...00000 {
> diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
> index 380969a..4e80205 100644
> --- a/drivers/iommu/arm-smmu-v3.c
> +++ b/drivers/iommu/arm-smmu-v3.c
> @@ -412,6 +412,9 @@
> #define MSI_IOVA_BASE 0x8000000
> #define MSI_IOVA_LENGTH 0x100000
>
> +#define ARM_SMMU_PAGE0_REGS_ONLY(smmu) \
> + ((smmu)->options & ARM_SMMU_OPT_PAGE0_REGS_ONLY)
At the two places we use this macro, frankly I think it would be clearer
to just reference smmu->options directly, as we currently do for
SKIP_PREFETCH. The abstraction also adds more lines than it saves...
> +
> static bool disable_bypass;
> module_param_named(disable_bypass, disable_bypass, bool, S_IRUGO);
> MODULE_PARM_DESC(disable_bypass,
> @@ -597,6 +600,7 @@ struct arm_smmu_device {
> u32 features;
>
> #define ARM_SMMU_OPT_SKIP_PREFETCH (1 << 0)
> +#define ARM_SMMU_OPT_PAGE0_REGS_ONLY (1 << 1)
Whitespace again, although this time it's spaces where there should be a
tab.
> u32 options;
>
> struct arm_smmu_cmdq cmdq;
> @@ -663,9 +667,19 @@ struct arm_smmu_option_prop {
>
> static struct arm_smmu_option_prop arm_smmu_options[] = {
> { ARM_SMMU_OPT_SKIP_PREFETCH, "hisilicon,broken-prefetch-cmd" },
> + { ARM_SMMU_OPT_PAGE0_REGS_ONLY, "cavium,cn9900-broken-page1-regspace"},
> { 0, NULL},
> };
>
> +static inline void __iomem *arm_smmu_page1_fixup(unsigned long offset,
> + struct arm_smmu_device *smmu)
> +{
> + if (offset > SZ_64K && ARM_SMMU_PAGE0_REGS_ONLY(smmu))
> + offset -= SZ_64K;
> +
> + return smmu->base + offset;
> +}
> +
> static struct arm_smmu_domain *to_smmu_domain(struct iommu_domain *dom)
> {
> return container_of(dom, struct arm_smmu_domain, domain);
> @@ -1961,8 +1975,8 @@ static int arm_smmu_init_one_queue(struct arm_smmu_device *smmu,
> return -ENOMEM;
> }
>
> - q->prod_reg = smmu->base + prod_off;
> - q->cons_reg = smmu->base + cons_off;
> + q->prod_reg = arm_smmu_page1_fixup(prod_off, smmu);
> + q->cons_reg = arm_smmu_page1_fixup(cons_off, smmu);
> q->ent_dwords = dwords;
>
> q->q_base = Q_BASE_RWA;
> @@ -2363,8 +2377,10 @@ static int arm_smmu_device_reset(struct arm_smmu_device *smmu, bool bypass)
>
> /* Event queue */
> writeq_relaxed(smmu->evtq.q.q_base, smmu->base + ARM_SMMU_EVTQ_BASE);
> - writel_relaxed(smmu->evtq.q.prod, smmu->base + ARM_SMMU_EVTQ_PROD);
> - writel_relaxed(smmu->evtq.q.cons, smmu->base + ARM_SMMU_EVTQ_CONS);
> + writel_relaxed(smmu->evtq.q.prod,
> + arm_smmu_page1_fixup(ARM_SMMU_EVTQ_PROD, smmu));
> + writel_relaxed(smmu->evtq.q.cons,
> + arm_smmu_page1_fixup(ARM_SMMU_EVTQ_CONS, smmu));
>
> enables |= CR0_EVTQEN;
> ret = arm_smmu_write_reg_sync(smmu, enables, ARM_SMMU_CR0,
> @@ -2379,9 +2395,9 @@ static int arm_smmu_device_reset(struct arm_smmu_device *smmu, bool bypass)
> writeq_relaxed(smmu->priq.q.q_base,
> smmu->base + ARM_SMMU_PRIQ_BASE);
> writel_relaxed(smmu->priq.q.prod,
> - smmu->base + ARM_SMMU_PRIQ_PROD);
> + arm_smmu_page1_fixup(ARM_SMMU_PRIQ_PROD, smmu));
> writel_relaxed(smmu->priq.q.cons,
> - smmu->base + ARM_SMMU_PRIQ_CONS);
> + arm_smmu_page1_fixup(ARM_SMMU_PRIQ_CONS, smmu));
>
> enables |= CR0_PRIQEN;
> ret = arm_smmu_write_reg_sync(smmu, enables, ARM_SMMU_CR0,
> @@ -2605,6 +2621,14 @@ static int arm_smmu_device_hw_probe(struct arm_smmu_device *smmu)
> }
>
> #ifdef CONFIG_ACPI
> +static void acpi_smmu_get_options(u32 model, struct arm_smmu_device *smmu)
> +{
> + if (model == ACPI_IORT_SMMU_CAVIUM_CN99XX)
> + smmu->options |= ARM_SMMU_OPT_PAGE0_REGS_ONLY;
> +
> + dev_notice(smmu->dev, "option mask 0x%x\n", smmu->options);
> +}
> +
> static int arm_smmu_device_acpi_probe(struct platform_device *pdev,
> struct arm_smmu_device *smmu)
> {
> @@ -2617,6 +2641,8 @@ static int arm_smmu_device_acpi_probe(struct platform_device *pdev,
> /* Retrieve SMMUv3 specific data */
> iort_smmu = (struct acpi_iort_smmu_v3 *)node->node_data;
>
> + acpi_smmu_get_options(iort_smmu->model, smmu);
> +
> if (iort_smmu->flags & ACPI_IORT_SMMU_V3_COHACC_OVERRIDE)
> smmu->features |= ARM_SMMU_FEAT_COHERENCY;
>
> @@ -2652,6 +2678,14 @@ static int arm_smmu_device_dt_probe(struct platform_device *pdev,
> return ret;
> }
>
> +static unsigned long arm_smmu_resource_size(struct arm_smmu_device *smmu)
> +{
> + if (ARM_SMMU_PAGE0_REGS_ONLY(smmu))
> + return SZ_64K;
> + else
> + return SZ_128K;
> +}
> +
> static int arm_smmu_device_probe(struct platform_device *pdev)
> {
> int irq, ret;
> @@ -2668,9 +2702,17 @@ static int arm_smmu_device_probe(struct platform_device *pdev)
> }
> smmu->dev = dev;
>
> + if (dev->of_node) {
> + ret = arm_smmu_device_dt_probe(pdev, smmu);
> + } else {
> + ret = arm_smmu_device_acpi_probe(pdev, smmu);
> + if (ret == -ENODEV)
> + return ret;
> + }
> +
> /* Base address */
> res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> - if (resource_size(res) + 1 < SZ_128K) {
> + if (resource_size(res) + 1 < arm_smmu_resource_size(smmu)) {
> dev_err(dev, "MMIO region too small (%pr)\n", res);
> return -EINVAL;
> }
> @@ -2697,14 +2739,6 @@ static int arm_smmu_device_probe(struct platform_device *pdev)
> if (irq > 0)
> smmu->gerr_irq = irq;
>
> - if (dev->of_node) {
> - ret = arm_smmu_device_dt_probe(pdev, smmu);
> - } else {
> - ret = arm_smmu_device_acpi_probe(pdev, smmu);
> - if (ret == -ENODEV)
> - return ret;
> - }
> -
> /* Set bypass mode according to firmware probing result */
> bypass = !!ret;
The bypass setting is directly related to the {dt,acpi}_probe logic, so
should move along with it. I can see that this ends up still working
because none of the interim code touches ret, but it does make things
unnecessarily hard to follow.
Robin.
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