[RFC v2 PATCH 08/14] irq: implement irq_send_ipi

[Qais Yousef]

There are 2 variants. __irq_desc_send_ipi() is meant to be used by arch code to
save the desc lookup when doing SMP IPIs.

irq_send_ipi() is meant for drivers that want to send IPIs to coprocessors they
interact with.

Signed-off-by: Qais Yousef <qais.yousef@xxxxxxxxxx>
---
 include/linux/irq.h |  3 +++
 kernel/irq/manage.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 47 insertions(+)

diff --git a/include/linux/irq.h b/include/linux/irq.h
index c3d0f26c3eff..32c740ac95b4 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -985,4 +985,7 @@ int irq_map_ipi(struct ipi_mapping *map,
 int irq_unmap_ipi(struct ipi_mapping *map,
 		  unsigned int cpu, irq_hw_number_t *hwirq);
 
+int __irq_desc_send_ipi(struct irq_desc *desc, const struct ipi_mask *dest);
+int irq_send_ipi(unsigned int virq, const struct ipi_mask *dest);
+
 #endif /* _LINUX_IRQ_H */
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 9a9bc0822c8f..f2425116a243 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -1983,3 +1983,47 @@ int irq_unmap_ipi(struct ipi_mapping *map,
 
 	return 0;
 }
+
+int __irq_desc_send_ipi(struct irq_desc *desc, const struct ipi_mask *dest)
+{
+	struct irq_data *data = irq_desc_get_irq_data(desc);
+	struct irq_chip *chip = irq_data_get_irq_chip(data);
+
+	if (!chip || !chip->irq_send_ipi)
+		return -EINVAL;
+
+	/*
+	 * Do not validate the mask for IPIs marked global. These are
+	 * regular IPIs so we can avoid the operation as their target
+	 * mask is the cpu_possible_mask.
+	 */
+	if (!dest->global) {
+		if (!bitmap_subset(dest->cpumask, data->ipi_mask.cpumask,
+				   dest->nbits))
+			return -EINVAL;
+	}
+
+	chip->irq_send_ipi(data, dest);
+	return 0;
+}
+
+/**
+ * irq_send_ipi() - send an IPI to target CPU(s)
+ * @irq: linux irq number from irq_reserve_ipi()
+ * @dest: dest CPU(s), must be the same or a subset of the mask passed to
+ *	  irq_reserve_ipi()
+ *
+ * Sends an IPI to all cpus in dest mask.
+ *
+ * Returns 0 on success and errno otherwise..
+ */
+int irq_send_ipi(unsigned int virq, const struct ipi_mask *dest)
+{
+	struct irq_desc *desc = irq_to_desc(virq);
+
+	if (!desc)
+		return -EINVAL;
+
+	return __irq_desc_send_ipi(desc, dest);
+}
+EXPORT_SYMBOL(irq_send_ipi);
-- 
2.1.0

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