Subject: Re: [PATCH v3 6/9] irqchip/ti-sci-intr: Add support for INTR being a parent to INTR

From: Marc Zyngier <[email-masked]>
Date: Sat, 25 Jul 2020 15:06:27 +0100

On Fri, 24 Jul 2020 15:18:34 +0100,
Lokesh Vutla <[email-masked]> wrote:
> 
> Driver assumes that Interrupt parent to Interrupt router is always GIC.
> This is not true always and an Interrupt Router can be a parent to
> Interrupt Router. Update the driver to detect the parent and request the
> parent irqs accordingly.
> 
> Signed-off-by: Lokesh Vutla <[email-masked]>
> ---
>  drivers/irqchip/irq-ti-sci-intr.c | 150 ++++++++++++++++++------------
>  1 file changed, 91 insertions(+), 59 deletions(-)
> 
> diff --git a/drivers/irqchip/irq-ti-sci-intr.c b/drivers/irqchip/irq-ti-sci-intr.c
> index 59d51a20bbd8..0b73816e77fc 100644
> --- a/drivers/irqchip/irq-ti-sci-intr.c
> +++ b/drivers/irqchip/irq-ti-sci-intr.c
> @@ -17,29 +17,18 @@
>  #include <linux/of_irq.h>
>  #include <linux/soc/ti/ti_sci_protocol.h>
>  
> -#define TI_SCI_DEV_ID_MASK	0xffff
> -#define TI_SCI_DEV_ID_SHIFT	16
> -#define TI_SCI_IRQ_ID_MASK	0xffff
> -#define TI_SCI_IRQ_ID_SHIFT	0
> -#define HWIRQ_TO_DEVID(hwirq)	(((hwirq) >> (TI_SCI_DEV_ID_SHIFT)) & \
> -				 (TI_SCI_DEV_ID_MASK))
> -#define HWIRQ_TO_IRQID(hwirq)	((hwirq) & (TI_SCI_IRQ_ID_MASK))
> -#define TO_HWIRQ(dev, index)	((((dev) & TI_SCI_DEV_ID_MASK) << \
> -				 TI_SCI_DEV_ID_SHIFT) | \
> -				((index) & TI_SCI_IRQ_ID_MASK))
> -
>  /**
>   * struct ti_sci_intr_irq_domain - Structure representing a TISCI based
>   *				   Interrupt Router IRQ domain.
>   * @sci:	Pointer to TISCI handle
> - * @dst_irq:	TISCI resource pointer representing GIC irq controller.
> - * @dst_id:	TISCI device ID of the GIC irq controller.
> + * @out_irqs:	TISCI resource pointer representing INTR irqs.
> + * @pdev:	Pointer to platform device.
>   * @type:	Specifies the trigger type supported by this Interrupt Router
>   */
>  struct ti_sci_intr_irq_domain {
>  	const struct ti_sci_handle *sci;
> -	struct ti_sci_resource *dst_irq;
> -	u32 dst_id;
> +	struct ti_sci_resource *out_irqs;
> +	struct platform_device *pdev;
>  	u32 type;
>  };
>  
> @@ -70,15 +59,44 @@ static int ti_sci_intr_irq_domain_translate(struct irq_domain *domain,
>  {
>  	struct ti_sci_intr_irq_domain *intr = domain->host_data;
>  
> -	if (fwspec->param_count != 2)
> +	if (fwspec->param_count != 1)
>  		return -EINVAL;
>  
> -	*hwirq = TO_HWIRQ(fwspec->param[0], fwspec->param[1]);
> +	*hwirq = fwspec->param[0];
>  	*type = intr->type;
>  
>  	return 0;
>  }
>  
> +/**
> + * ti_sci_intr_xlate_irq() - Translate hwirq to parent's hwirq.
> + * @intr:	IRQ domain corresponding to Interrupt Router
> + * @irq:	Hardware irq corresponding to the above irq domain
> + *
> + * Return parent irq number if translation is available else -ENOENT.
> + */
> +static int ti_sci_intr_xlate_irq(struct ti_sci_intr_irq_domain *intr, u32 irq)
> +{
> +	struct device_node *np = dev_of_node(&intr->pdev->dev);
> +	u32 base, pbase, size, len;
> +	const __be32 *range;
> +
> +	range = of_get_property(np, "ti,interrupt-ranges", &len);
> +	if (!range)
> +		return irq;
> +
> +	for (len /= sizeof(*range); len >= 3; len -= 3) {
> +		base = be32_to_cpu(*range++);
> +		pbase = be32_to_cpu(*range++);
> +		size = be32_to_cpu(*range++);
> +
> +		if (base <= irq && irq < base + size)
> +			return irq - base + pbase;
> +	}
> +
> +	return -ENOENT;
> +}
> +
>  /**
>   * ti_sci_intr_irq_domain_free() - Free the specified IRQs from the domain.
>   * @domain:	Domain to which the irqs belong
> @@ -89,66 +107,77 @@ static void ti_sci_intr_irq_domain_free(struct irq_domain *domain,
>  					unsigned int virq, unsigned int nr_irqs)
>  {
>  	struct ti_sci_intr_irq_domain *intr = domain->host_data;
> -	struct irq_data *data, *parent_data;
> -	u16 dev_id, irq_index;
> +	struct irq_data *data;
> +	int out_irq;
>  
> -	parent_data = irq_domain_get_irq_data(domain->parent, virq);
>  	data = irq_domain_get_irq_data(domain, virq);
> -	irq_index = HWIRQ_TO_IRQID(data->hwirq);
> -	dev_id = HWIRQ_TO_DEVID(data->hwirq);
> +	out_irq = (uintptr_t)data->chip_data;
>  
> -	intr->sci->ops.rm_irq_ops.free_irq(intr->sci, dev_id, irq_index,
> -					   intr->dst_id, parent_data->hwirq);
> -	ti_sci_release_resource(intr->dst_irq, parent_data->hwirq);
> +	intr->sci->ops.rm_irq_ops.free_irq(intr->sci,
> +					   intr->pdev->id, data->hwirq,
> +					   intr->pdev->id, out_irq);
> +	ti_sci_release_resource(intr->out_irqs, out_irq);
>  	irq_domain_free_irqs_parent(domain, virq, 1);
>  	irq_domain_reset_irq_data(data);
>  }
>  
>  /**
> - * ti_sci_intr_alloc_gic_irq() - Allocate GIC specific IRQ
> + * ti_sci_intr_alloc_parent_irq() - Allocate parent IRQ
>   * @domain:	Pointer to the interrupt router IRQ domain
>   * @virq:	Corresponding Linux virtual IRQ number
>   * @hwirq:	Corresponding hwirq for the IRQ within this IRQ domain
>   *
> - * Returns 0 if all went well else appropriate error pointer.
> + * Returns parent irq if all went well else appropriate error pointer.
>   */
> -static int ti_sci_intr_alloc_gic_irq(struct irq_domain *domain,
> -				     unsigned int virq, u32 hwirq)
> +static int ti_sci_intr_alloc_parent_irq(struct irq_domain *domain,
> +					unsigned int virq, u32 hwirq)
>  {
>  	struct ti_sci_intr_irq_domain *intr = domain->host_data;
> +	struct device_node *parent_node;
>  	struct irq_fwspec fwspec;
> -	u16 dev_id, irq_index;
> -	u16 dst_irq;
> -	int err;
> -
> -	dev_id = HWIRQ_TO_DEVID(hwirq);
> -	irq_index = HWIRQ_TO_IRQID(hwirq);
> +	u16 out_irq, p_hwirq;
> +	int err = 0;
>  
> -	dst_irq = ti_sci_get_free_resource(intr->dst_irq);
> -	if (dst_irq == TI_SCI_RESOURCE_NULL)
> +	out_irq = ti_sci_get_free_resource(intr->out_irqs);
> +	if (out_irq == TI_SCI_RESOURCE_NULL)
>  		return -EINVAL;
>  
> -	fwspec.fwnode = domain->parent->fwnode;
> -	fwspec.param_count = 3;
> -	fwspec.param[0] = 0;	/* SPI */
> -	fwspec.param[1] = dst_irq - 32; /* SPI offset */
> -	fwspec.param[2] = intr->type;
> +	p_hwirq = ti_sci_intr_xlate_irq(intr, out_irq);
> +	if (p_hwirq < 0)
> +		goto err_irqs;
> +
> +	parent_node = of_irq_find_parent(dev_of_node(&intr->pdev->dev));
> +	fwspec.fwnode = of_node_to_fwnode(parent_node);
> +	if (of_property_read_u32(parent_node, "#interrupt-cells",
> +				 &fwspec.param_count))
> +		goto err_irqs;
> +
> +	if (of_device_is_compatible(parent_node, "arm,gic-v3")) {
> +		/* Parent is GIC */
> +		fwspec.param[0] = 0;	/* SPI */
> +		fwspec.param[1] = p_hwirq - 32; /* SPI offset */
> +		fwspec.param[2] = intr->type;

So you pick up param_count from the parent node, but:
- you don't check that you have indeed at least 3 cells (unlikely to
  fail, but still)
- you leave the rest of the param array uninitialised if param_count
  was > 3, which is allowed by the GICv3 binding.

This definitely needs fixing.

> +	} else {
> +		/* Parent is Interrupt Router */
> +		fwspec.param[0] = p_hwirq;
> +	}
>  
>  	err = irq_domain_alloc_irqs_parent(domain, virq, 1, &fwspec);
>  	if (err)
>  		goto err_irqs;
>  
> -	err = intr->sci->ops.rm_irq_ops.set_irq(intr->sci, dev_id, irq_index,
> -						intr->dst_id, dst_irq);
> +	err = intr->sci->ops.rm_irq_ops.set_irq(intr->sci,
> +						intr->pdev->id, hwirq,
> +						intr->pdev->id, out_irq);
>  	if (err)
>  		goto err_msg;
>  
> -	return 0;
> +	return p_hwirq;
>  
>  err_msg:
>  	irq_domain_free_irqs_parent(domain, virq, 1);
>  err_irqs:
> -	ti_sci_release_resource(intr->dst_irq, dst_irq);
> +	ti_sci_release_resource(intr->out_irqs, out_irq);
>  	return err;
>  }
>  
> @@ -168,18 +197,19 @@ static int ti_sci_intr_irq_domain_alloc(struct irq_domain *domain,
>  	struct irq_fwspec *fwspec = data;
>  	unsigned long hwirq;
>  	unsigned int flags;
> -	int err;
> +	int err, p_hwirq;
>  
>  	err = ti_sci_intr_irq_domain_translate(domain, fwspec, &hwirq, &flags);
>  	if (err)
>  		return err;
>  
> -	err = ti_sci_intr_alloc_gic_irq(domain, virq, hwirq);
> -	if (err)
> -		return err;
> +	p_hwirq = ti_sci_intr_alloc_parent_irq(domain, virq, hwirq);
> +	if (p_hwirq < 0)
> +		return p_hwirq;
>  
>  	irq_domain_set_hwirq_and_chip(domain, virq, hwirq,
> -				      &ti_sci_intr_irq_chip, NULL);
> +				      &ti_sci_intr_irq_chip,
> +				      (void *)(uintptr_t)p_hwirq);
>  
>  	return 0;
>  }
> @@ -214,6 +244,7 @@ static int ti_sci_intr_irq_domain_probe(struct platform_device *pdev)
>  	if (!intr)
>  		return -ENOMEM;
>  
> +	intr->pdev = pdev;
>  	ret = of_property_read_u32(dev_of_node(dev), "ti,intr-trigger-type",
>  				   &intr->type);
>  	if (ret) {
> @@ -230,19 +261,18 @@ static int ti_sci_intr_irq_domain_probe(struct platform_device *pdev)
>  		return ret;
>  	}
>  
> -	ret = of_property_read_u32(dev_of_node(dev), "ti,sci-dst-id",
> -				   &intr->dst_id);
> +	ret = of_property_read_u32(dev_of_node(dev), "ti,sci-dev-id",
> +				   &pdev->id);

This feels very dodgy. You are hijacking a random field in the
platform device data structure, which shouldn't be any of your
business. What was wrong with having a separate field for something
that is obviously platform specific?

>  	if (ret) {
> -		dev_err(dev, "missing 'ti,sci-dst-id' property\n");
> +		dev_err(dev, "missing 'ti,sci-dev-id' property\n");
>  		return -EINVAL;
>  	}
>  
> -	intr->dst_irq = devm_ti_sci_get_of_resource(intr->sci, dev,
> -						    intr->dst_id,
> -						    "ti,sci-rm-range-girq");
> -	if (IS_ERR(intr->dst_irq)) {
> +	intr->out_irqs = devm_ti_sci_get_resource(intr->sci, dev, pdev->id,
> +					TI_SCI_RESASG_SUBTYPE_IR_OUTPUT);
> +	if (IS_ERR(intr->out_irqs)) {
>  		dev_err(dev, "Destination irq resource allocation failed\n");
> -		return PTR_ERR(intr->dst_irq);
> +		return PTR_ERR(intr->out_irqs);
>  	}
>  
>  	domain = irq_domain_add_hierarchy(parent_domain, 0, 0, dev_of_node(dev),
> @@ -252,6 +282,8 @@ static int ti_sci_intr_irq_domain_probe(struct platform_device *pdev)
>  		return -ENOMEM;
>  	}
>  
> +	dev_info(dev, "Interrupt Router %d domain created\n", pdev->id);
> +
>  	return 0;
>  }
>  
> -- 
> 2.27.0
> 
> 

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.

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