Re: [PATCH 3/3] irqchip/gic: assign irqchip dynamically

From: Marc Zyngier
Date: Wed Dec 09 2015 - 09:16:03 EST


On 23/10/15 23:15, Linus Walleij wrote:
> Instead of having the irqchip being a static struct, make it part
> of the per-instance data so we can assign it a dynamic name. This
> has the usable side effect of displaying the GIC with an instance
> number as GIC0, GIC1 ... GICn in /proc/interrupts, which is helpful
> when debugging cascaded GICs, such as on the ARM PB11MPCore.
>
> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Cc: Jason Cooper <jason@xxxxxxxxxxxxxx>
> Cc: Marc Zyngier <marc.zyngier@xxxxxxx>
> Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
> ---
> ChangeLog v1->v2:
> - Keep the static structs around, just delete the .name
> field assign them to the chips at registration time, updating
> the name field with the instance number.
> - Also enumerate the EOIMODE1 sub-chips.
> - Broke out this irqchip stuff from the rest of the series so as
> not to stress the irqchip maintainers. It has no dependencies
> on the other patches anyways, and can be merged stand-alone.
>
> Marc: can't test the EOIMODE1 thing, it's far above me, but it
> "should work". Is it correct that there is one unique and coupled
> EOIMODE1 instance per GIC instance like this?
> ---
> drivers/irqchip/irq-gic.c | 16 ++++++++++++----
> 1 file changed, 12 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/irqchip/irq-gic.c b/drivers/irqchip/irq-gic.c
> index 9ec8cf5137d9..fe87ac32fdbe 100644
> --- a/drivers/irqchip/irq-gic.c
> +++ b/drivers/irqchip/irq-gic.c
> @@ -58,6 +58,8 @@ union gic_base {
> };
>
> struct gic_chip_data {
> + struct irq_chip chip;
> + struct irq_chip eoimode1_chip;

This seems overkill: A given GIC instance is either driven as a GIC or
a GICv2. Never both at the same time.

> union gic_base dist_base;
> union gic_base cpu_base;
> #ifdef CONFIG_CPU_PM
> @@ -370,7 +372,6 @@ static void gic_handle_cascade_irq(struct irq_desc *desc)
> }
>
> static struct irq_chip gic_chip = {
> - .name = "GIC",
> .irq_mask = gic_mask_irq,
> .irq_unmask = gic_unmask_irq,
> .irq_eoi = gic_eoi_irq,
> @@ -386,7 +387,6 @@ static struct irq_chip gic_chip = {
> };
>
> static struct irq_chip gic_eoimode1_chip = {
> - .name = "GICv2",
> .irq_mask = gic_eoimode1_mask_irq,
> .irq_unmask = gic_unmask_irq,
> .irq_eoi = gic_eoimode1_eoi_irq,
> @@ -880,11 +880,12 @@ void __init gic_init_physaddr(struct device_node *node)
> static int gic_irq_domain_map(struct irq_domain *d, unsigned int irq,
> irq_hw_number_t hw)
> {
> - struct irq_chip *chip = &gic_chip;
> + struct gic_chip_data *gic = d->host_data;
> + struct irq_chip *chip = &gic->chip;
>
> if (static_key_true(&supports_deactivate)) {
> if (d->host_data == (void *)&gic_data[0])
> - chip = &gic_eoimode1_chip;
> + chip = &gic->eoimode1_chip;
> }
>
> if (hw < 32) {
> @@ -989,6 +990,13 @@ static void __init __gic_init_bases(unsigned int gic_nr, int irq_start,
> BUG_ON(gic_nr >= MAX_GIC_NR);
>
> gic = &gic_data[gic_nr];
> +
> + /* Initialize irq_chip */
> + gic->chip = gic_chip;
> + gic->eoimode1_chip = gic_eoimode1_chip;
> + gic->chip.name = kasprintf(GFP_KERNEL, "GIC%d", gic_nr);
> + gic->eoimode1_chip.name = kasprintf(GFP_KERNEL, "GICv2%d", gic_nr);

And there is only ever one GIC in the system that can be driven as a
GICv2 - it can only be instance 0.

> +
> #ifdef CONFIG_GIC_NON_BANKED
> if (percpu_offset) { /* Frankein-GIC without banked registers... */
> unsigned int cpu;
>

So instead of going for another round, how about this on top of your
patch:

diff --git a/drivers/irqchip/irq-gic.c b/drivers/irqchip/irq-gic.c
index 428f9c1..174990c 100644
--- a/drivers/irqchip/irq-gic.c
+++ b/drivers/irqchip/irq-gic.c
@@ -70,7 +70,6 @@ union gic_base {

struct gic_chip_data {
struct irq_chip chip;
- struct irq_chip eoimode1_chip;
union gic_base dist_base;
union gic_base cpu_base;
#ifdef CONFIG_CPU_PM
@@ -400,6 +399,7 @@ static struct irq_chip gic_chip = {
};

static struct irq_chip gic_eoimode1_chip = {
+ .name = "GICv2",
.irq_mask = gic_eoimode1_mask_irq,
.irq_unmask = gic_unmask_irq,
.irq_eoi = gic_eoimode1_eoi_irq,
@@ -926,20 +926,14 @@ static int gic_irq_domain_map(struct irq_domain *d, unsigned int irq,
irq_hw_number_t hw)
{
struct gic_chip_data *gic = d->host_data;
- struct irq_chip *chip = &gic->chip;
-
- if (static_key_true(&supports_deactivate)) {
- if (d->host_data == (void *)&gic_data[0])
- chip = &gic->eoimode1_chip;
- }

if (hw < 32) {
irq_set_percpu_devid(irq);
- irq_domain_set_info(d, irq, hw, chip, d->host_data,
+ irq_domain_set_info(d, irq, hw, &gic->chip, d->host_data,
handle_percpu_devid_irq, NULL, NULL);
irq_set_status_flags(irq, IRQ_NOAUTOEN);
} else {
- irq_domain_set_info(d, irq, hw, chip, d->host_data,
+ irq_domain_set_info(d, irq, hw, &gic->chip, d->host_data,
handle_fasteoi_irq, NULL, NULL);
irq_set_probe(irq);
}
@@ -1048,10 +1042,12 @@ static void __init __gic_init_bases(unsigned int gic_nr, int irq_start,
gic = &gic_data[gic_nr];

/* Initialize irq_chip */
- gic->chip = gic_chip;
- gic->eoimode1_chip = gic_eoimode1_chip;
- gic->chip.name = kasprintf(GFP_KERNEL, "GIC%d", gic_nr);
- gic->eoimode1_chip.name = kasprintf(GFP_KERNEL, "GICv2%d", gic_nr);
+ if (static_key_true(&supports_deactivate) && gic_nr == 0) {
+ gic->chip = gic_eoimode1_chip;
+ } else {
+ gic->chip = gic_chip;
+ gic->chip.name = kasprintf(GFP_KERNEL, "GIC-%d", gic_nr);
+ }

#ifdef CONFIG_GIC_NON_BANKED
if (percpu_offset) { /* Frankein-GIC without banked registers... */

If you're OK with this and the previous patch, I'll squash those into
the original ones, and put it on a branch for Thomas to pick up for 4.5.

Thanks,

M.
--
Jazz is not dead. It just smells funny...
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