[PATCH 07/14] genirq: Add a new generic IPI reservation code to irq core

Qais Yousef
2015-11-03T11:13:45Z

Add a generic mechanism to dynamically allocate an IPI.

With this change the user can call irq_reserve_ipi() to dynamically allocate an
IPI and use the associated virq to send one to 1 or more cpus.

Signed-off-by: Qais Yousef <qais.yousef@imgtec.com>
---
include/linux/irqdomain.h | 6 +++
kernel/irq/irqdomain.c | 98 +++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 104 insertions(+)

diff --git a/include/linux/irqdomain.h b/include/linux/irqdomain.h
index 422b6a1617b8..9ba67bfe8ad2 100644
--- a/include/linux/irqdomain.h
+++ b/include/linux/irqdomain.h
@@ -39,6 +39,7 @@ struct irq_domain;
struct of_device_id;
struct irq_chip;
struct irq_data;
+struct ipi_mask;

/* Number of irqs reserved for a legacy isa controller */
#define NUM_ISA_INTERRUPTS 16
@@ -333,6 +334,11 @@ int irq_domain_xlate_onetwocell(struct irq_domain *d, struct device_node *ctrlr,
const u32 *intspec, unsigned int intsize,
irq_hw_number_t *out_hwirq, unsigned int *out_type);

+/* IPI functions */
+unsigned int irq_reserve_ipi(struct irq_domain *domain,
+ const struct ipi_mask *dest);
+void irq_destroy_ipi(unsigned int irq);
+
/* V2 interfaces to support hierarchy IRQ domains. */
extern struct irq_data *irq_domain_get_irq_data(struct irq_domain *domain,
unsigned int virq);
diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
index 22aa9612ef7c..dd240914301d 100644
--- a/kernel/irq/irqdomain.c
+++ b/kernel/irq/irqdomain.c
@@ -852,6 +852,104 @@ static int irq_domain_alloc_descs(int virq, unsigned int cnt,
return virq;
}

+/**
+ * irq_reserve_ipi() - setup an IPI to destination cpumask
+ * @domain: IPI domain
+ * @dest: cpumask of cpus to receive the IPI
+ *
+ * Allocate a virq that can be used to send IPI to any CPU in dest mask.
+ *
+ * On success it'll return linux irq number and 0 on failure
+ */
+unsigned int irq_reserve_ipi(struct irq_domain *domain,
+ const struct ipi_mask *dest)
+{
+ struct irq_data *data;
+ unsigned int nr_irqs;
+ int virq, i;
+
+ if (domain == NULL) {
+ pr_warn("Must provide a valid IPI domain!\n");
+ return 0;
+ }
+
+ if (!irq_domain_is_ipi(domain)) {
+ pr_warn("Not an IPI domain!\n");
+ return 0;
+ }
+
+ /* always allocate a virq per cpu */
+ nr_irqs = ipi_mask_weight(dest);
+
+ virq = irq_domain_alloc_descs(-1, nr_irqs, 0, NUMA_NO_NODE);
+ if (virq <= 0) {
+ pr_warn("Can't reserve IPI, failed to alloc descs\n");
+ return 0;
+ }
+
+ virq = __irq_domain_alloc_irqs(domain, virq, nr_irqs, NUMA_NO_NODE,
+ (void *) dest, true);
+ if (virq <= 0) {
+ pr_warn("Can't reserve IPI, failed to alloc irqs\n");
+ goto free_descs;
+ }
+
+ for (i = virq; i < virq + nr_irqs; i++) {
+ data = irq_get_irq_data(i);
+ data->common->ipi_mask = ipi_mask_alloc(dest->nbits);
+ if (!data->common->ipi_mask)
+ goto free_ipi_mask;
+ ipi_mask_copy(data->common->ipi_mask, dest);
+ }
+
+ return virq;
+
+free_ipi_mask:
+ for (i = virq; i < virq + nr_irqs; i++) {
+ data = irq_get_irq_data(i);
+ ipi_mask_free(data->common->ipi_mask);
+ }
+free_descs:
+ irq_free_descs(virq, nr_irqs);
+ return 0;
+}
+
+/**
+ * irq_destroy_ipi() - unreserve an IPI that was previously allocated
+ * @irq: linux irq number to be destroyed
+ *
+ * Return the IPIs allocated with irq_reserve_ipi() to the system destroying all
+ * virqs associated with them.
+ */
+void irq_destroy_ipi(unsigned int irq)
+{
+ struct irq_data *data = irq_get_irq_data(irq);
+ struct irq_domain *domain;
+ unsigned int nr_irqs, i;
+
+ if (!irq || !data)
+ return;
+
+ domain = data->domain;
+ if (WARN_ON(domain == NULL))
+ return;
+
+ if (!irq_domain_is_ipi(domain)) {
+ pr_warn("Not an IPI domain!\n");
+ return;
+ }
+
+ nr_irqs = ipi_mask_weight(data->common->ipi_mask);
+ ipi_mask_free(data->common->ipi_mask);
+
+ for (i = irq + 1; i < irq + nr_irqs; i++) {
+ data = irq_get_irq_data(i);
+ ipi_mask_free(data->common->ipi_mask);
+ }
+
+ irq_domain_free_irqs(irq, nr_irqs);
+}
+
#ifdef CONFIG_IRQ_DOMAIN_HIERARCHY
/**
* irq_domain_create_hierarchy - Add a irqdomain into the hierarchy
--
2.1.0