Re: [PATCH V2 03/19] irqchip: crossbar: Skip some irqs from getting mapped to crossbar

[Sricharan R <r.sricharan@ti.com>]

Hi Jason,

On Thursday 12 June 2014 07:37 PM, Jason Cooper wrote:
> On Thu, Jun 12, 2014 at 06:49:17PM +0530, Sricharan R wrote:
>> Hi Jason,
>>
>> On Thursday 12 June 2014 06:21 PM, Jason Cooper wrote:
>>> On Thu, Jun 12, 2014 at 05:23:11PM +0530, Sricharan R wrote:
>>>> From: Nishanth Menon <nm@ti.com>
>>>>
>>>> When, in the system due to varied reasons, interrupts might be unusable
>>>> due to hardware behavior, but register maps do exist, then those interrupts
>>>> should be skipped while mapping irq to crossbars.
>>>>
>>>> Signed-off-by: Nishanth Menon <nm@ti.com>
>>>> Signed-off-by: Sricharan R <r.sricharan@ti.com>
>>>> Signed-off-by: Tony Lindgren <tony@atomide.com>
>>>
>>> Tony, have you applied these somewhere already?
>>>
>>>> ---
>>>>  drivers/irqchip/irq-crossbar.c |   47 ++++++++++++++++++++++++++++++++++++----
>>>>  1 file changed, 43 insertions(+), 4 deletions(-)
>>>>
>>>> diff --git a/drivers/irqchip/irq-crossbar.c b/drivers/irqchip/irq-crossbar.c
>>>> index 51d4b87..847f6e3 100644
>>>> --- a/drivers/irqchip/irq-crossbar.c
>>>> +++ b/drivers/irqchip/irq-crossbar.c
>>>> @@ -13,11 +13,13 @@
>>>>  #include <linux/io.h>
>>>>  #include <linux/of_address.h>
>>>>  #include <linux/of_irq.h>
>>>> +#include <linux/of_device.h>
>>>>  #include <linux/slab.h>
>>>>  #include <linux/irqchip/arm-gic.h>
>>>>  
>>>>  #define IRQ_FREE	-1
>>>>  #define IRQ_RESERVED	-2
>>>> +#define IRQ_SKIP	-3
>>>>  #define GIC_IRQ_START	32
>>>>  
>>>>  /*
>>>> @@ -34,6 +36,16 @@ struct crossbar_device {
>>>>  	void (*write) (int, int);
>>>>  };
>>>>  
>>>> +/**
>>>> + * struct crossbar_data: Platform specific data
>>>> + * @irqs_unused: array of irqs that cannot be used because of hw erratas
>>>> + * @size: size of the irqs_unused array
>>>> + */
>>>> +struct crossbar_data {
>>>> +	const uint *irqs_unused;
>>>> +	const uint size;
>>>> +};
>>>> +
>>>>  static struct crossbar_device *cb;
>>>>  
>>>>  static inline void crossbar_writel(int irq_no, int cb_no)
>>>> @@ -119,10 +131,12 @@ const struct irq_domain_ops routable_irq_domain_ops = {
>>>>  	.xlate = crossbar_domain_xlate
>>>>  };
>>>>  
>>>> -static int __init crossbar_of_init(struct device_node *node)
>>>> +static int __init crossbar_of_init(struct device_node *node,
>>>> +				   const struct crossbar_data *data)
>>>>  {
>>>>  	int i, size, max, reserved = 0, entry;
>>>>  	const __be32 *irqsr;
>>>> +	const int *irqsk = NULL;
>>>>  
>>>>  	cb = kzalloc(sizeof(*cb), GFP_KERNEL);
>>>>  
>>>> @@ -194,6 +208,22 @@ static int __init crossbar_of_init(struct device_node *node)
>>>>  		reserved += size;
>>>>  	}
>>>>  
>>>> +	/* Skip the ones marked as unused */
>>>> +	if (data) {
>>>> +		irqsk = data->irqs_unused;
>>>> +		size = data->size;
>>>> +
>>>> +		for (i = 0; i < size; i++) {
>>>> +			entry = irqsk[i];
>>>> +
>>>> +			if (entry > max) {
>>>> +				pr_err("Invalid skip entry\n");
>>>> +				goto err3;
>>>> +			}
>>>> +			cb->irq_map[entry] = IRQ_SKIP;
>>>> +		}
>>>> +	}
>>>> +
>>>>  	register_routable_domain_ops(&routable_irq_domain_ops);
>>>>  	return 0;
>>>>  
>>>> @@ -208,18 +238,27 @@ err1:
>>>>  	return -ENOMEM;
>>>>  }
>>>>  
>>>> +/* irq number 10 cannot be used because of hw bug */
>>>> +int dra_irqs_unused[] = { 10 };
>>>> +struct crossbar_data cb_dra_data = { dra_irqs_unused,
>>>> +				     ARRAY_SIZE(dra_irqs_unused) };
>>>> +
>>>>  static const struct of_device_id crossbar_match[] __initconst = {
>>>> -	{ .compatible = "ti,irq-crossbar" },
>>>> +	{ .compatible = "ti,irq-crossbar", .data = &cb_dra_data },
>>>>  	{}
>>>>  };
>>>
>>> This is a bug in all implementations of this IP?  Or, a specific
>>> SoC's implementation?  Would this be better expressed in the dts via a
>>> property?  Can we expect future implementations to be fixed?
>>>
>>> thx,
>>>
>>> Jason.
>>  Infact this and PATCH#10 should be merged. I will change that.
>>
>>  So in Socs's (2 so far) that do have a crossbar, some irqs are mapped
>>  through a crossbar and some are directly wired to the irqchip.
>>  These 'unused irqs' are those which are directly wired but they still
>>  have a crossbar register. Their routing cannot be changed. So this
>>  is not really expected usage of the crossbar hw ip. We initially thought
>>  having a dts property separately for this, but took this path to avoid
>>  loading the dts with additional bindings which may not be generic.
> 
> How do you plan to handle future SoCs with this IP and possibly
> different hard-wired irqs?
  Yes, that would require adding a new compatible in the above list and dts.
  So if adding a new binding in the dts would be cleaner, then i will change
  it that way.

Regards,
 Sricharan