Subject: Re: [RFC PATCH 2/2] irqchip/ti-sci-intr: Add support for INTR being a parent to INTR

From: Lokesh Vutla <[email-masked]>
Date: Fri, 4 Oct 2019 09:07:43 +0530

Hi Marc,

On 02/10/19 6:42 PM, Marc Zyngier wrote:
> On Mon, 23 Sep 2019 09:54:05 +0530
> Lokesh Vutla <[email-masked]> wrote:
> 
>> Driver assumes that Interrupt parent to Interrupt router is always GIC.
>> This is not true always and a 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 | 137 ++++++++++++++++++------------
>>  1 file changed, 82 insertions(+), 55 deletions(-)
>>
>> diff --git a/drivers/irqchip/irq-ti-sci-intr.c b/drivers/irqchip/irq-ti-sci-intr.c
>> index 59d51a20bbd8..1d8aaa871798 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 +59,43 @@ 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;
> 
> As I said in reply to the first patch, this breaks badly. Except that
> this time this is a new kernel on an old DT.
> 
>>  
>> -	*hwirq = TO_HWIRQ(fwspec->param[0], fwspec->param[1]);
>> +	*hwirq = fwspec->param[0];
>>  	*type = intr->type;
>>  
>>  	return 0;
>>  }
>>  
>> +static int ti_sci_intr_xlate_irq(struct ti_sci_intr_irq_domain *intr,
>> +				 u32 irq, bool to_parent_hwirq)
>> +{
>> +	struct device_node *np = dev_of_node(&intr->pdev->dev);
>> +	u32 base, pbase, size, len;
>> +	const __be32 *range;
>> +
>> +	range = of_get_property(np, "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 (to_parent_hwirq) {
>> +			if (base <= irq && irq < base + size)
>> +				return irq - base + pbase;
>> +		} else {
>> +			if (pbase <= irq && irq < pbase + size)
>> +				return irq - pbase + base;
>> +		}
> 
> Using the same function to compute two different things is really ugly.
> It'd be nicer if you had xlate_hwirq_to_parent() and
> xlate_parent_to_hwirq(), each one doing their job.

Sure will update with two separate functions.

> 
> Also, it isn't clear to me why there is only a single tuple in the
> interrupt-ranges property. Is it a guarantee that you'll never have
> multiple ranges?

Right there can be multiple ranges. This function handles multiple ranges as you
described.

> 
>> +	}
>> +
>> +	return -ENOENT;
>> +}
>> +
>>  /**
>>   * ti_sci_intr_irq_domain_free() - Free the specified IRQs from the domain.
>>   * @domain:	Domain to which the irqs belong
>> @@ -90,56 +107,72 @@ static void ti_sci_intr_irq_domain_free(struct irq_domain *domain,
>>  {
>>  	struct ti_sci_intr_irq_domain *intr = domain->host_data;
>>  	struct irq_data *data, *parent_data;
>> -	u16 dev_id, irq_index;
>> +	int out_irq;
>>  
>>  	parent_data = irq_domain_get_irq_data(domain->parent, virq);
>> +	out_irq = ti_sci_intr_xlate_irq(intr, parent_data->hwirq, false);
>>  	data = irq_domain_get_irq_data(domain, virq);
>> -	irq_index = HWIRQ_TO_IRQID(data->hwirq);
>> -	dev_id = HWIRQ_TO_DEVID(data->hwirq);
>>  
>> -	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.
>>   */
>> -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;
>> +	u16 out_irq, p_hwirq;
>> +	int err = 0;
>>  
>> -	dev_id = HWIRQ_TO_DEVID(hwirq);
>> -	irq_index = HWIRQ_TO_IRQID(hwirq);
>> -
>> -	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, true);
>> +	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 (fwspec.param_count == 1) {
>> +		/* Parent is Interrupt Router */
>> +		fwspec.param[0] = p_hwirq;
>> +	} else if (fwspec.param_count == 3) {
>> +		/* Parent is GIC */
>> +		fwspec.param[0] = 0;	/* SPI */
>> +		fwspec.param[1] = p_hwirq; /* SPI offset */
>> +		fwspec.param[2] = intr->type;
>> +	} else {
> 
> It really looks like you're flipping a coin and hope to hit the right
> backend. It feels terribly fragile, and it would be a lot simpler if
> the firmware actually exposed the "type" of parent controller, rather
> than this guesswork.

hmm..Firmware is bumb in this respect. It only programs what ever values are
provided with a minor policing on values. User should know the IRQ hierarchy and
call firmware in each step. In this case firmware cannot specify the parent
"type" as there can be multiple parents routed to different cores(like A72 or R5).

Do you suggest any better alternative?

Thanks and regards,
Lokesh

> 
>> +		/* Invalid parent */
>> +		dev_err(&intr->pdev->dev, "Unknown IRQ parent to INTR\n");
>> +		goto err_irqs;
>> +	}
>>  
>>  	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;
>>  
>> @@ -148,7 +181,7 @@ static int ti_sci_intr_alloc_gic_irq(struct irq_domain *domain,
>>  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;
>>  }
>>  
>> @@ -174,7 +207,7 @@ static int ti_sci_intr_irq_domain_alloc(struct irq_domain *domain,
>>  	if (err)
>>  		return err;
>>  
>> -	err = ti_sci_intr_alloc_gic_irq(domain, virq, hwirq);
>> +	err = ti_sci_intr_alloc_parent_irq(domain, virq, hwirq);
>>  	if (err)
>>  		return err;
>>  
>> @@ -214,6 +247,7 @@ 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 +264,10 @@ 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);
>> -	if (ret) {
>> -		dev_err(dev, "missing 'ti,sci-dst-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_irq_range(intr->sci, dev);
>> +	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 +277,8 @@ 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;
>>  }
>>  
> 
> Thanks,
> 
> 	M.
> 

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