[PATCH 2/4] irqdomain: augment add_simple() to allocate descs

[Linus Walleij]

From: Linus Walleij <linus.walleij at linaro.org>

Currently we rely on all IRQ chip instances to dynamically
allocate their IRQ descriptors unless they use the linear
IRQ domain. So for irqdomain_add_legacy() and
irqdomain_add_simple() the caller need to make sure that
descriptors are allocated.

Let's slightly augment the yet unused irqdomain_add_simple()
to also allocate descriptors as a means to simplify usage
and avoid code duplication throughout the kernel.

We warn if descriptors cannot be allocated, e.g. if a
platform has the bad habit of hogging descriptors at boot
time.

Cc: Rob Herring <rob.herring at calxeda.com>
Cc: Thomas Gleixner <tglx at linutronix.de>
Cc: Grant Likely <grant.likely at secretlab.ca>
Cc: Russell King <linux at arm.linux.org.uk>
Cc: Lee Jones <lee.jones at linaro.org>
Signed-off-by: Linus Walleij <linus.walleij at linaro.org>
---
Rob/Grant/Thomas if you ACK this I will take it through the
pinctrl tree since I introduce its only user right there.
---
 kernel/irq/irqdomain.c | 21 ++++++++++++++++-----
 1 file changed, 16 insertions(+), 5 deletions(-)

diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
index 49a7772..a0655b6 100644
--- a/kernel/irq/irqdomain.c
+++ b/kernel/irq/irqdomain.c
@@ -148,7 +148,8 @@ static unsigned int irq_domain_legacy_revmap(struct irq_domain *domain,
  * @host_data: Controller private data pointer
  *
  * Allocates a legacy irq_domain if irq_base is positive or a linear
- * domain otherwise.
+ * domain otherwise. For the legacy domain, IRQ descriptors will also
+ * be allocated.
  *
  * This is intended to implement the expected behaviour for most
  * interrupt controllers which is that a linear mapping should
@@ -162,11 +163,21 @@ struct irq_domain *irq_domain_add_simple(struct device_node *of_node,
 					 const struct irq_domain_ops *ops,
 					 void *host_data)
 {
-	if (first_irq > 0)
-		return irq_domain_add_legacy(of_node, size, first_irq, 0,
+	if (first_irq > 0) {
+		int irq_base;
+
+		irq_base = irq_alloc_descs(first_irq, 0, size, numa_node_id());
+		if (irq_base < 0) {
+			WARN(1, "Cannot allocate irq_descs @ IRQ%d, assuming pre-allocated\n",
+			     first_irq);
+			irq_base = first_irq;
+		}
+		return irq_domain_add_legacy(of_node, size, irq_base, 0,
 					     ops, host_data);
-	else
-		return irq_domain_add_linear(of_node, size, ops, host_data);
+	}
+
+	/* A linear domain is the default */
+	return irq_domain_add_linear(of_node, size, ops, host_data);
 }
 
 /**
-- 
1.7.11.3