[PATCH v4 1/7] irq/irq_sim: add a notifier chain

From: Bartosz Golaszewski
Date: Thu Feb 14 2019 - 08:43:25 EST


From: Bartosz Golaszewski <bgolaszewski@xxxxxxxxxxxx>

Provide a helper allowing users to register a notifier block with
a simulator. For now the only event we're notifying about is a change
in type configuration.

This is required by the gpio-mockup module which wants to track the
state of GPIO lines and simulate rising and falling edge interrupts.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@xxxxxxxxxxxx>
---
include/linux/irq_sim.h | 22 ++++++++++++++++++----
kernel/irq/irq_sim.c | 40 ++++++++++++++++++++++++++++++++++++++++
2 files changed, 58 insertions(+), 4 deletions(-)

diff --git a/include/linux/irq_sim.h b/include/linux/irq_sim.h
index 4500d453a63e..e076693d0af7 100644
--- a/include/linux/irq_sim.h
+++ b/include/linux/irq_sim.h
@@ -8,12 +8,21 @@

#include <linux/irq_work.h>
#include <linux/device.h>
+#include <linux/notifier.h>

/*
* Provides a framework for allocating simulated interrupts which can be
* requested like normal irqs and enqueued from process context.
*/

+#define IRQ_SIM_TYPE_CHANGED 1
+
+/* Passed to notifier callbacks when type changes. */
+struct irq_sim_irq_type {
+ unsigned int offset;
+ unsigned int type;
+};
+
struct irq_sim_work_ctx {
struct irq_work work;
unsigned long *pending;
@@ -22,13 +31,16 @@ struct irq_sim_work_ctx {
struct irq_sim_irq_ctx {
int irqnum;
bool enabled;
+ struct irq_sim *parent;
+ struct irq_sim_irq_type type;
};

struct irq_sim {
- struct irq_sim_work_ctx work_ctx;
- int irq_base;
- unsigned int irq_count;
- struct irq_sim_irq_ctx *irqs;
+ struct irq_sim_work_ctx work_ctx;
+ int irq_base;
+ unsigned int irq_count;
+ struct irq_sim_irq_ctx *irqs;
+ struct atomic_notifier_head notifier;
};

int irq_sim_init(struct irq_sim *sim, unsigned int num_irqs);
@@ -37,5 +49,7 @@ int devm_irq_sim_init(struct device *dev, struct irq_sim *sim,
void irq_sim_fini(struct irq_sim *sim);
void irq_sim_fire(struct irq_sim *sim, unsigned int offset);
int irq_sim_irqnum(struct irq_sim *sim, unsigned int offset);
+int irq_sim_notifier_register(struct irq_sim *sim,
+ struct notifier_block *nb);

#endif /* _LINUX_IRQ_SIM_H */
diff --git a/kernel/irq/irq_sim.c b/kernel/irq/irq_sim.c
index 98a20e1594ce..a55641e78125 100644
--- a/kernel/irq/irq_sim.c
+++ b/kernel/irq/irq_sim.c
@@ -25,10 +25,34 @@ static void irq_sim_irqunmask(struct irq_data *data)
irq_ctx->enabled = true;
}

+static int irq_sim_set_type(struct irq_data *data, unsigned int type)
+{
+ struct irq_sim_irq_ctx *irq_ctx = irq_data_get_irq_chip_data(data);
+ struct irq_sim *sim = irq_ctx->parent;
+ int rv;
+
+ /* Only support rising and falling edge types. */
+ if (type & ~IRQ_TYPE_EDGE_BOTH)
+ return -EINVAL;
+
+ irq_ctx->type.type = type;
+
+ rv = atomic_notifier_call_chain(&sim->notifier,
+ IRQ_SIM_TYPE_CHANGED,
+ &irq_ctx->type);
+ if (rv < 0) {
+ pr_err("%s: error calling the type notifier chain\n", __func__);
+ return rv;
+ }
+
+ return 0;
+}
+
static struct irq_chip irq_sim_irqchip = {
.name = "irq_sim",
.irq_mask = irq_sim_irqmask,
.irq_unmask = irq_sim_irqunmask,
+ .irq_set_type = irq_sim_set_type,
};

static void irq_sim_handle_irq(struct irq_work *work)
@@ -83,7 +107,9 @@ int irq_sim_init(struct irq_sim *sim, unsigned int num_irqs)

for (i = 0; i < num_irqs; i++) {
sim->irqs[i].irqnum = sim->irq_base + i;
+ sim->irqs[i].parent = sim;
sim->irqs[i].enabled = false;
+ sim->irqs[i].type.offset = i;
irq_set_chip(sim->irq_base + i, &irq_sim_irqchip);
irq_set_chip_data(sim->irq_base + i, &sim->irqs[i]);
irq_set_handler(sim->irq_base + i, &handle_simple_irq);
@@ -91,6 +117,7 @@ int irq_sim_init(struct irq_sim *sim, unsigned int num_irqs)
IRQ_NOREQUEST | IRQ_NOAUTOEN, IRQ_NOPROBE);
}

+ ATOMIC_INIT_NOTIFIER_HEAD(&sim->notifier);
init_irq_work(&sim->work_ctx.work, irq_sim_handle_irq);
sim->irq_count = num_irqs;

@@ -180,3 +207,16 @@ int irq_sim_irqnum(struct irq_sim *sim, unsigned int offset)
return sim->irqs[offset].irqnum;
}
EXPORT_SYMBOL_GPL(irq_sim_irqnum);
+
+/**
+ * irq_sim_notifier_register - Subscribe for interrupt simulator events.
+ *
+ * @sim: The interrupt simulator object.
+ * @nb: Notifier block.
+ */
+int irq_sim_notifier_register(struct irq_sim *sim,
+ struct notifier_block *nb)
+{
+ return atomic_notifier_chain_register(&sim->notifier, nb);
+}
+EXPORT_SYMBOL_GPL(irq_sim_notifier_register);
--
2.20.1