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SubjectRe: [PATCH v2 2/9] irq/irq_sim: use irq domain
On Tue, 29 Jan 2019 09:44:04 +0100
Bartosz Golaszewski <brgl@bgdev.pl> wrote:

> From: Bartosz Golaszewski <bgolaszewski@baylibre.com>
>
> Delegate the offset to virq number mapping to the provided framework
> instead of handling it locally. Use the legacy domain as we want to
> preallocate the irq descriptors.

Why?

>
> Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
> ---
> include/linux/irq_sim.h | 6 +--
> kernel/irq/irq_sim.c | 94 +++++++++++++++++++++++++++++------------
> 2 files changed, 71 insertions(+), 29 deletions(-)
>
> diff --git a/include/linux/irq_sim.h b/include/linux/irq_sim.h
> index eda132c22b57..b96c2f752320 100644
> --- a/include/linux/irq_sim.h
> +++ b/include/linux/irq_sim.h
> @@ -8,6 +8,7 @@
>
> #include <linux/irq.h>
> #include <linux/irq_work.h>
> +#include <linux/irqdomain.h>
> #include <linux/device.h>
>
> /*
> @@ -21,16 +22,15 @@ struct irq_sim_work_ctx {
> };
>
> struct irq_sim_irq_ctx {
> - int irqnum;
> bool enabled;
> };
>
> struct irq_sim {
> struct irq_chip chip;
> + struct irq_domain *domain;
> struct irq_sim_work_ctx work_ctx;
> - int irq_base;
> + int virq_base;
> unsigned int irq_count;
> - struct irq_sim_irq_ctx *irqs;
> };
>
> int irq_sim_init(struct irq_sim *sim, unsigned int num_irqs);
> diff --git a/kernel/irq/irq_sim.c b/kernel/irq/irq_sim.c
> index b732e4e2e45b..2bcdbab1bc5a 100644
> --- a/kernel/irq/irq_sim.c
> +++ b/kernel/irq/irq_sim.c
> @@ -44,6 +44,43 @@ static void irq_sim_handle_irq(struct irq_work *work)
> }
> }
>
> +static int irq_sim_domain_map(struct irq_domain *domain,
> + unsigned int virq, irq_hw_number_t hw)
> +{
> + struct irq_sim *sim = domain->host_data;
> + struct irq_sim_irq_ctx *ctx;
> +
> + ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
> + if (!ctx)
> + return -ENOMEM;
> +
> + irq_set_chip(virq, &sim->chip);
> + irq_set_chip_data(virq, ctx);
> + irq_set_handler(virq, handle_simple_irq);

Consider using modern APIs such as irq_domain_set_info().

> + irq_modify_status(virq, IRQ_NOREQUEST | IRQ_NOAUTOEN, IRQ_NOPROBE);

Where is this requirement coming from?

> +
> + return 0;
> +}
> +
> +static void irq_sim_domain_free(struct irq_domain *domain,
> + unsigned int virq, unsigned int num_irqs)
> +{
> + struct irq_sim_irq_ctx *ctx;
> + struct irq_data *irq;
> + int i;
> +
> + for (i = 0; i < num_irqs; i++) {
> + irq = irq_domain_get_irq_data(domain, virq + i);
> + ctx = irq_data_get_irq_chip_data(irq);
> + kfree(ctx);
> + }
> +}
> +
> +static const struct irq_domain_ops irq_sim_domain_ops = {
> + .map = irq_sim_domain_map,
> + .free = irq_sim_domain_free,

The intended use of the v2 API is to have alloc and free as a pair, and
no map. So please choose which version of the API you're using here.
The safest bet would be to move what you do on map into alloc.

> +};
> +
> /**
> * irq_sim_init - Initialize the interrupt simulator: allocate a range of
> * dummy interrupts.
> @@ -56,16 +93,15 @@ static void irq_sim_handle_irq(struct irq_work *work)
> */
> int irq_sim_init(struct irq_sim *sim, unsigned int num_irqs)
> {
> - int i;
> -
> - sim->irqs = kmalloc_array(num_irqs, sizeof(*sim->irqs), GFP_KERNEL);
> - if (!sim->irqs)
> + sim->virq_base = irq_alloc_descs(-1, 0, num_irqs, 0);
> + if (sim->virq_base < 0)
> + return sim->virq_base;
> +
> + sim->domain = irq_domain_add_legacy(NULL, num_irqs, sim->virq_base,
> + 0, &irq_sim_domain_ops, sim);

Why do you need a legacy domain? As far as I can tell, this is new
code, hence it has no legacy.

> + if (!sim->domain) {
> + irq_free_descs(sim->virq_base, num_irqs);
> return -ENOMEM;
> -
> - sim->irq_base = irq_alloc_descs(-1, 0, num_irqs, 0);
> - if (sim->irq_base < 0) {
> - kfree(sim->irqs);
> - return sim->irq_base;
> }
>
> sim->chip.name = "irq_sim";
> @@ -74,25 +110,15 @@ int irq_sim_init(struct irq_sim *sim, unsigned int num_irqs)
>
> sim->work_ctx.pending = bitmap_zalloc(num_irqs, GFP_KERNEL);
> if (!sim->work_ctx.pending) {
> - kfree(sim->irqs);
> - irq_free_descs(sim->irq_base, num_irqs);
> + irq_domain_remove(sim->domain);
> + irq_free_descs(sim->virq_base, num_irqs);
> return -ENOMEM;
> }
>
> - for (i = 0; i < num_irqs; i++) {
> - sim->irqs[i].irqnum = sim->irq_base + i;
> - sim->irqs[i].enabled = false;
> - irq_set_chip(sim->irq_base + i, &sim->chip);
> - irq_set_chip_data(sim->irq_base + i, &sim->irqs[i]);
> - irq_set_handler(sim->irq_base + i, &handle_simple_irq);
> - irq_modify_status(sim->irq_base + i,
> - IRQ_NOREQUEST | IRQ_NOAUTOEN, IRQ_NOPROBE);
> - }
> -
> init_irq_work(&sim->work_ctx.work, irq_sim_handle_irq);
> sim->irq_count = num_irqs;
>
> - return sim->irq_base;
> + return sim->virq_base;
> }
> EXPORT_SYMBOL_GPL(irq_sim_init);
>
> @@ -106,8 +132,8 @@ void irq_sim_fini(struct irq_sim *sim)
> {
> irq_work_sync(&sim->work_ctx.work);
> bitmap_free(sim->work_ctx.pending);
> - irq_free_descs(sim->irq_base, sim->irq_count);
> - kfree(sim->irqs);
> + irq_domain_free_irqs(sim->virq_base, sim->irq_count);
> + irq_domain_remove(sim->domain);
> }
> EXPORT_SYMBOL_GPL(irq_sim_fini);
>
> @@ -151,6 +177,20 @@ int devm_irq_sim_init(struct device *dev, struct irq_sim *sim,
> }
> EXPORT_SYMBOL_GPL(devm_irq_sim_init);
>
> +static struct irq_sim_irq_ctx *
> +irq_sim_get_ctx(struct irq_sim *sim, unsigned int offset)
> +{
> + struct irq_sim_irq_ctx *ctx;
> + struct irq_data *irq;
> + int virq;
> +
> + virq = irq_find_mapping(sim->domain, offset);
> + irq = irq_domain_get_irq_data(sim->domain, virq);
> + ctx = irq_data_get_irq_chip_data(irq);
> +
> + return ctx;
> +}
> +
> /**
> * irq_sim_fire - Enqueue an interrupt.
> *
> @@ -159,7 +199,9 @@ EXPORT_SYMBOL_GPL(devm_irq_sim_init);
> */
> void irq_sim_fire(struct irq_sim *sim, unsigned int offset)
> {
> - if (sim->irqs[offset].enabled) {
> + struct irq_sim_irq_ctx *ctx = irq_sim_get_ctx(sim, offset);
> +
> + if (ctx->enabled) {
> set_bit(offset, sim->work_ctx.pending);
> irq_work_queue(&sim->work_ctx.work);
> }
> @@ -175,6 +217,6 @@ EXPORT_SYMBOL_GPL(irq_sim_fire);
> */
> int irq_sim_irqnum(struct irq_sim *sim, unsigned int offset)
> {
> - return sim->irqs[offset].irqnum;
> + return irq_find_mapping(sim->domain, offset);
> }
> EXPORT_SYMBOL_GPL(irq_sim_irqnum);


Thanks,

M.
--
Without deviation from the norm, progress is not possible.

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