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Date: Thu, 12 Jun 2014 10:07:29 -0400
From: Jason Cooper <jason@...edaemon.net>
To: Sricharan R <r.sricharan@...com>
Cc: linux-omap@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
tony@...mide.com, santosh.shilimkar@...com, nm@...com,
rnayak@...com, linux@....linux.org.uk, tglx@...utronix.de
Subject: Re: [PATCH V2 03/19] irqchip: crossbar: Skip some irqs from
getting mapped to crossbar
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@...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@...com>
> >> Signed-off-by: Sricharan R <r.sricharan@...com>
> >> Signed-off-by: Tony Lindgren <tony@...mide.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?
thx,
Jason.
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