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

Regards,
Sricharan




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