Re: [PATCH v2 4/4] perf/smmuv3: Add MSI irq support

[Robin Murphy]

On 2018-07-24 12:45 PM, Shameer Kolothum wrote:
> This adds support for MSI based counter overflow interrupt.
>
> Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@xxxxxxxxxx>
> ---
>   drivers/perf/arm_smmuv3_pmu.c | 105 +++++++++++++++++++++++++++++++++---------
>   1 file changed, 84 insertions(+), 21 deletions(-)
>
> diff --git a/drivers/perf/arm_smmuv3_pmu.c b/drivers/perf/arm_smmuv3_pmu.c
> index b3dc394..ca69813 100644
> --- a/drivers/perf/arm_smmuv3_pmu.c
> +++ b/drivers/perf/arm_smmuv3_pmu.c
> @@ -94,6 +94,10 @@
>   #define SMMU_PMCG_IRQ_CFG2              0xE64
>   #define SMMU_PMCG_IRQ_STATUS            0xE68
>   
> +/* MSI config fields */
> +#define MSI_CFG0_ADDR_MASK              GENMASK_ULL(51, 2)
> +#define MSI_CFG2_MEMATTR_DEVICE_nGnRE   0x1
> +
>   #define SMMU_COUNTER_RELOAD             BIT(31)
>   #define SMMU_DEFAULT_FILTER_SEC         0
>   #define SMMU_DEFAULT_FILTER_SPAN        1
> @@ -657,14 +661,89 @@ static irqreturn_t smmu_pmu_handle_irq(int irq_num, void *data)
>   	return IRQ_HANDLED;
>   }
>   
> +static void smmu_pmu_free_msis(void *data)
> +{
> +	struct device *dev = data;
> +
> +	platform_msi_domain_free_irqs(dev);
> +}
> +
> +static void smmu_pmu_write_msi_msg(struct msi_desc *desc, struct msi_msg *msg)
> +{
> +	phys_addr_t doorbell;
> +	struct device *dev = msi_desc_to_dev(desc);
> +	struct smmu_pmu *pmu = dev_get_drvdata(dev);
> +
> +	doorbell = (((u64)msg->address_hi) << 32) | msg->address_lo;
> +	doorbell &= MSI_CFG0_ADDR_MASK;
> +
> +	writeq_relaxed(doorbell, pmu->reg_base + SMMU_PMCG_IRQ_CFG0);
> +	writel_relaxed(msg->data, pmu->reg_base + SMMU_PMCG_IRQ_CFG1);
> +	writel_relaxed(MSI_CFG2_MEMATTR_DEVICE_nGnRE,
> +				pmu->reg_base + SMMU_PMCG_IRQ_CFG2);
> +}
> +
> +static void smmu_pmu_setup_msi(struct smmu_pmu *pmu)
> +{
> +	struct msi_desc *desc;
> +	struct device *dev = pmu->dev;
> +	int ret;
> +
> +	/* Clear MSI address reg */
> +	writeq_relaxed(0, pmu->reg_base + SMMU_PMCG_IRQ_CFG0);
> +
> +	/* MSI supported or not */
> +	if (!(readl(pmu->reg_base + SMMU_PMCG_CFGR) & SMMU_PMCG_CFGR_MSI))
> +		return;
> +
> +	ret = platform_msi_domain_alloc_irqs(dev, 1, smmu_pmu_write_msi_msg);
> +	if (ret) {
> +		dev_warn(dev, "failed to allocate MSIs\n");
> +		return;
> +	}
> +
> +	desc = first_msi_entry(dev);
> +	if (desc)
> +		pmu->irq = desc->irq;
> +
> +	/* Add callback to free MSIs on teardown */
> +	devm_add_action(dev, smmu_pmu_free_msis, dev);
> +}
> +
> +static int smmu_pmu_setup_irq(struct smmu_pmu *pmu)
> +{
> +	int irq, ret = -ENXIO;
> +
> +	smmu_pmu_setup_msi(pmu);
> +
> +	irq = pmu->irq;
> +	if (irq)
> +		ret = devm_request_irq(pmu->dev, irq, smmu_pmu_handle_irq,
> +			       IRQF_NOBALANCING | IRQF_SHARED | IRQF_NO_THREAD,
> +			       "smmu-v3-pmu", pmu);
> +	return ret;
> +}
> +
>   static int smmu_pmu_reset(struct smmu_pmu *smmu_pmu)
>   {
> +	int ret;
> +
>   	/* Disable counter and interrupt */
>   	writeq(smmu_pmu->counter_present_mask,
>   			smmu_pmu->reg_base + SMMU_PMCG_CNTENCLR0);
>   	writeq(smmu_pmu->counter_present_mask,
>   		smmu_pmu->reg_base + SMMU_PMCG_INTENCLR0);
>   
> +	ret = smmu_pmu_setup_irq(smmu_pmu);

Why are we moving this out of probe? We may perform a reset more than 
once (e.g. if we get round to system PM support), at which point this 
looks logically wrong.

Robin.

> +	if (ret) {
> +		dev_err(smmu_pmu->dev, "failed to setup irqs\n");
> +		return ret;
> +	}
> +
> +	/* Pick one CPU to be the preferred one to use */
> +	smmu_pmu->on_cpu = smp_processor_id();
> +	WARN_ON(irq_set_affinity(smmu_pmu->irq, cpumask_of(smmu_pmu->on_cpu)));
> +
>   	smmu_pmu_disable(&smmu_pmu->pmu);
>   	return 0;
>   }
> @@ -738,26 +817,8 @@ static int smmu_pmu_probe(struct platform_device *pdev)
>   	}
>   
>   	irq = platform_get_irq(pdev, 0);
> -	if (irq < 0) {
> -		dev_err(dev, "Failed to get valid irq for smmu @%pa\n",
> -			&mem_resource_0->start);
> -		return irq;
> -	}
> -
> -	err = devm_request_irq(dev, irq, smmu_pmu_handle_irq,
> -			       IRQF_NOBALANCING | IRQF_SHARED | IRQF_NO_THREAD,
> -			       "smmu-pmu", smmu_pmu);
> -	if (err) {
> -		dev_err(dev,
> -			"Unable to request IRQ%d for SMMU PMU counters\n", irq);
> -		return err;
> -	}
> -
> -	smmu_pmu->irq = irq;
> -
> -	/* Pick one CPU to be the preferred one to use */
> -	smmu_pmu->on_cpu = smp_processor_id();
> -	WARN_ON(irq_set_affinity(smmu_pmu->irq, cpumask_of(smmu_pmu->on_cpu)));
> +	if (irq > 0)
> +		smmu_pmu->irq = irq;
>   
>   	smmu_pmu->num_counters = get_num_counters(smmu_pmu);
>   	smmu_pmu->counter_present_mask = GENMASK(smmu_pmu->num_counters - 1, 0);
> @@ -765,7 +826,9 @@ static int smmu_pmu_probe(struct platform_device *pdev)
>   		    SMMU_PMCG_CFGR_SIZE_MASK) >> SMMU_PMCG_CFGR_SIZE_SHIFT;
>   	smmu_pmu->counter_mask = GENMASK_ULL(reg_size, 0);
>   
> -	smmu_pmu_reset(smmu_pmu);
> +	err = smmu_pmu_reset(smmu_pmu);
> +	if (err)
> +		return err;
>   
>   	err = cpuhp_state_add_instance_nocalls(cpuhp_state_num,
>   					       &smmu_pmu->node);