Subject: [PATCH 1/2 v2] irqdomain: add support for creating a continous mapping

From: Sebastian Andrzej Siewior <[email-masked]>
Date: Fri, 21 Feb 2014 09:57:36 +0100

A MSI device may have multiple interrupts. That means that the
interrupts numbers should be continuos so that pdev->irq refers to the
first interrupt, pdev->irq + 1 to the second and so on.
This patch adds support for continuous allocation of virqs for a range
of hwirqs. The function is based on irq_create_mapping() but due to the
number argument there is very little in common now.

Cc: Thomas Gleixner <[email-masked]>
Signed-off-by: Sebastian Andrzej Siewior <[email-masked]>
---
Scott, this is what you suggested. I must admit, it does not look that
bad. It is just compile tested.

v1.v2:
    - use irq_create_mapping_block() for irq_create_mapping()

 include/linux/irqdomain.h | 10 ++++--
 kernel/irq/irqdomain.c    | 87 ++++++++++++++++++++++++++++++++++-------------
 2 files changed, 72 insertions(+), 25 deletions(-)

diff --git a/include/linux/irqdomain.h b/include/linux/irqdomain.h
index c983ed1..8b09a6b 100644
--- a/include/linux/irqdomain.h
+++ b/include/linux/irqdomain.h
@@ -171,12 +171,18 @@ extern int irq_domain_associate(struct irq_domain *domain, unsigned int irq,
 					irq_hw_number_t hwirq);
 extern void irq_domain_associate_many(struct irq_domain *domain,
 				      unsigned int irq_base,
 				      irq_hw_number_t hwirq_base, int count);
 
-extern unsigned int irq_create_mapping(struct irq_domain *host,
-				       irq_hw_number_t hwirq);
+extern unsigned int irq_create_mapping_block(struct irq_domain *host,
+		irq_hw_number_t hwirq, unsigned int num);
+static inline unsigned int irq_create_mapping(struct irq_domain *host,
+		irq_hw_number_t hwirq)
+{
+	return irq_create_mapping_block(host, hwirq, 1);
+}
+
 extern void irq_dispose_mapping(unsigned int virq);
 
 /**
  * irq_linear_revmap() - Find a linux irq from a hw irq number.
  * @domain: domain owning this hardware interrupt
diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
index cf68bb3..cdc6627 100644
--- a/kernel/irq/irqdomain.c
+++ b/kernel/irq/irqdomain.c
@@ -372,67 +372,108 @@ unsigned int irq_create_direct_mapping(struct irq_domain *domain)
 
 	return virq;
 }
 EXPORT_SYMBOL_GPL(irq_create_direct_mapping);
 
+static int irq_check_continuous_mapping(struct irq_domain *domain,
+		irq_hw_number_t hwirq, unsigned int num)
+{
+	int virq;
+	int i;
+
+	virq = irq_find_mapping(domain, hwirq);
+
+	for (i = 1; i < num; i++) {
+		unsigned int next;
+
+		next = irq_find_mapping(domain, hwirq + i);
+		if (next == virq + i)
+			continue;
+
+		pr_err("irq: invalid partial mapping. First hwirq %lu maps to "
+				"%d and \n", hwirq, virq);
+		pr_err("irq: +%d hwirq (%lu) maps to %d but should be %d.\n",
+				i, hwirq + i, next, virq + i);
+		return -EINVAL;
+	}
+
+	pr_debug("-> existing mapping on virq %d\n", virq);
+	return virq;
+}
+
 /**
- * irq_create_mapping() - Map a hardware interrupt into linux irq space
+ * irq_create_mapping_block() - Map multiple hardware interrupts
  * @domain: domain owning this hardware interrupt or NULL for default domain
  * @hwirq: hardware irq number in that domain space
+ * @num: number of interrupts
+ *
+ * Maps a hwirq to a newly allocated virq. If num is greater than 1 then num
+ * hwirqs (hwirq … hwirq + num - 1) will be mapped and virq will be  continuous.
+ * Returns the first linux virq number.
  *
- * Only one mapping per hardware interrupt is permitted. Returns a linux
- * irq number.
  * If the sense/trigger is to be specified, set_irq_type() should be called
  * on the number returned from that call.
  */
-unsigned int irq_create_mapping(struct irq_domain *domain,
-				irq_hw_number_t hwirq)
+unsigned int irq_create_mapping_block(struct irq_domain *domain,
+		irq_hw_number_t hwirq, unsigned int num)
 {
-	unsigned int hint;
 	int virq;
+	int i;
+	int node;
+	unsigned int hint;
 
-	pr_debug("irq_create_mapping(0x%p, 0x%lx)\n", domain, hwirq);
+	pr_debug("%s(0x%p, 0x%lx, %d)\n", __func__, domain, hwirq, num);
 
 	/* Look for default domain if nececssary */
-	if (domain == NULL)
+	if (!domain && num == 1)
 		domain = irq_default_domain;
+
 	if (domain == NULL) {
 		WARN(1, "%s(, %lx) called with NULL domain\n", __func__, hwirq);
 		return 0;
 	}
 	pr_debug("-> using domain @%p\n", domain);
 
 	/* Check if mapping already exists */
-	virq = irq_find_mapping(domain, hwirq);
-	if (virq) {
-		pr_debug("-> existing mapping on virq %d\n", virq);
-		return virq;
+	for (i = 0; i < num; i++) {
+		virq = irq_find_mapping(domain, hwirq + i);
+		if (virq != NO_IRQ) {
+			if (i == 0)
+				return irq_check_continuous_mapping(domain,
+						hwirq, num);
+			pr_err("irq: hwirq %ld has no mapping but hwirq %ld "
+				"maps to virq %d. This can't be a block\n",
+				hwirq, hwirq + i, virq);
+			return -EINVAL;
+		}
 	}
 
+	node = of_node_to_nid(domain->of_node);
 	/* Allocate a virtual interrupt number */
 	hint = hwirq % nr_irqs;
 	if (hint == 0)
 		hint++;
-	virq = irq_alloc_desc_from(hint, of_node_to_nid(domain->of_node));
-	if (virq <= 0)
-		virq = irq_alloc_desc_from(1, of_node_to_nid(domain->of_node));
+	virq = irq_alloc_descs_from(hint, num, node);
+	if (virq <= 0 && hint != 1)
+		virq = irq_alloc_descs_from(1, num, node);
 	if (virq <= 0) {
 		pr_debug("-> virq allocation failed\n");
 		return 0;
 	}
 
-	if (irq_domain_associate(domain, virq, hwirq)) {
-		irq_free_desc(virq);
-		return 0;
+	irq_domain_associate_many(domain, virq, hwirq, num);
+	if (num == 1) {
+		pr_debug("irq %lu on domain %s mapped to virtual irq %u\n",
+			hwirq, of_node_full_name(domain->of_node), virq);
+		return virq;
 	}
-
-	pr_debug("irq %lu on domain %s mapped to virtual irq %u\n",
-		hwirq, of_node_full_name(domain->of_node), virq);
-
+	pr_debug("irqs %lu…%lu on domain %s mapped to virtual irqs %u…%u\n",
+		hwirq, hwirq + num - 1, of_node_full_name(domain->of_node),
+			virq, virq + num - 1);
 	return virq;
 }
-EXPORT_SYMBOL_GPL(irq_create_mapping);
+EXPORT_SYMBOL_GPL(irq_create_mapping_block);
 
 /**
  * irq_create_strict_mappings() - Map a range of hw irqs to fixed linux irqs
  * @domain: domain owning the interrupt range
  * @irq_base: beginning of linux IRQ range
-- 
1.9.0.rc3