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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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