[PATCH 16/39] irqdomain: Make normal and nomap irqdomains exclusive

[Marc Zyngier]

Direct mappings are completely exclusive of normal mappings, meaning
that we can refactor the code slightly so that we can get rid of
the revmap_direct_max_irq field and use the revmap_size field
instead, reducing the size of the irqdomain structure.

Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
---
 include/linux/irqdomain.h |  6 +++---
 kernel/irq/irqdomain.c    | 45 ++++++++++++++++++++++++++++++---------
 2 files changed, 38 insertions(+), 13 deletions(-)

diff --git a/include/linux/irqdomain.h b/include/linux/irqdomain.h
index 723495ec5a2f..0916cf9c6e20 100644
--- a/include/linux/irqdomain.h
+++ b/include/linux/irqdomain.h
@@ -149,8 +149,6 @@ struct irq_domain_chip_generic;
  * @parent: Pointer to parent irq_domain to support hierarchy irq_domains
  *
  * Revmap data, used internally by irq_domain
- * @revmap_direct_max_irq: The largest hwirq that can be set for controllers that
- *                         support direct mapping
  * @revmap_size: Size of the linear map table @revmap[]
  * @revmap_tree: Radix map tree for hwirqs that don't fit in the linear map
  * @revmap: Linear table of hwirq->virq reverse mappings
@@ -173,7 +171,6 @@ struct irq_domain {
 
 	/* reverse map data. The linear map gets appended to the irq_domain */
 	irq_hw_number_t hwirq_max;
-	unsigned int revmap_direct_max_irq;
 	unsigned int revmap_size;
 	struct radix_tree_root revmap_tree;
 	struct mutex revmap_tree_mutex;
@@ -207,6 +204,9 @@ enum {
 	 */
 	IRQ_DOMAIN_MSI_NOMASK_QUIRK	= (1 << 6),
 
+	/* Irq domain doesn't translate anything */
+	IRQ_DOMAIN_FLAG_NO_MAP		= (1 << 7),
+
 	/*
 	 * Flags starting from IRQ_DOMAIN_FLAG_NONCORE are reserved
 	 * for implementation specific purposes and ignored by the
diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
index e0143e640683..fa94c86e47d4 100644
--- a/kernel/irq/irqdomain.c
+++ b/kernel/irq/irqdomain.c
@@ -146,6 +146,10 @@ struct irq_domain *__irq_domain_add(struct fwnode_handle *fwnode, int size,
 
 	static atomic_t unknown_domains;
 
+	if (WARN_ON((size && direct_max) ||
+		    (!IS_ENABLED(CONFIG_IRQ_DOMAIN_NOMAP) && direct_max)))
+		return NULL;
+
 	domain = kzalloc_node(sizeof(*domain) + (sizeof(unsigned int) * size),
 			      GFP_KERNEL, of_node_to_nid(to_of_node(fwnode)));
 	if (!domain)
@@ -213,8 +217,14 @@ struct irq_domain *__irq_domain_add(struct fwnode_handle *fwnode, int size,
 	domain->ops = ops;
 	domain->host_data = host_data;
 	domain->hwirq_max = hwirq_max;
+
+	if (direct_max) {
+		size = direct_max;
+		domain->flags |= IRQ_DOMAIN_FLAG_NO_MAP;
+	}
+
 	domain->revmap_size = size;
-	domain->revmap_direct_max_irq = direct_max;
+
 	irq_domain_check_hierarchy(domain);
 
 	mutex_lock(&irq_domain_mutex);
@@ -482,9 +492,18 @@ struct irq_domain *irq_get_default_host(void)
 	return irq_default_domain;
 }
 
+static bool irq_domain_is_nomap(struct irq_domain *domain)
+{
+	return IS_ENABLED(CONFIG_IRQ_DOMAIN_NOMAP) &&
+	       (domain->flags & IRQ_DOMAIN_FLAG_NO_MAP);
+}
+
 static void irq_domain_clear_mapping(struct irq_domain *domain,
 				     irq_hw_number_t hwirq)
 {
+	if (irq_domain_is_nomap(domain))
+		return;
+
 	if (hwirq < domain->revmap_size) {
 		domain->revmap[hwirq] = 0;
 	} else {
@@ -498,6 +517,9 @@ static void irq_domain_set_mapping(struct irq_domain *domain,
 				   irq_hw_number_t hwirq,
 				   struct irq_data *irq_data)
 {
+	if (irq_domain_is_nomap(domain))
+		return;
+
 	if (hwirq < domain->revmap_size) {
 		domain->revmap[hwirq] = irq_data->irq;
 	} else {
@@ -629,9 +651,9 @@ unsigned int irq_create_direct_mapping(struct irq_domain *domain)
 		pr_debug("create_direct virq allocation failed\n");
 		return 0;
 	}
-	if (virq >= domain->revmap_direct_max_irq) {
+	if (virq >= domain->revmap_size) {
 		pr_err("ERROR: no free irqs available below %i maximum\n",
-			domain->revmap_direct_max_irq);
+			domain->revmap_size);
 		irq_free_desc(virq);
 		return 0;
 	}
@@ -879,10 +901,14 @@ unsigned int irq_find_mapping(struct irq_domain *domain,
 	if (domain == NULL)
 		return 0;
 
-	if (hwirq < domain->revmap_direct_max_irq) {
-		data = irq_domain_get_irq_data(domain, hwirq);
-		if (data && data->hwirq == hwirq)
-			return hwirq;
+	if (irq_domain_is_nomap(domain)) {
+		if (hwirq < domain->revmap_size) {
+			data = irq_domain_get_irq_data(domain, hwirq);
+			if (data && data->hwirq == hwirq)
+				return hwirq;
+		}
+
+		return 0;
 	}
 
 	/* Check if the hwirq is in the linear revmap. */
@@ -1470,7 +1496,7 @@ static void irq_domain_fix_revmap(struct irq_data *d)
 {
 	void __rcu **slot;
 
-	if (d->hwirq < d->domain->revmap_size)
+	if (irq_domain_is_nomap(d->domain) || d->hwirq < d->domain->revmap_size)
 		return; /* Not using radix tree. */
 
 	/* Fix up the revmap. */
@@ -1830,8 +1856,7 @@ static void
 irq_domain_debug_show_one(struct seq_file *m, struct irq_domain *d, int ind)
 {
 	seq_printf(m, "%*sname:   %s\n", ind, "", d->name);
-	seq_printf(m, "%*ssize:   %u\n", ind + 1, "",
-		   d->revmap_size + d->revmap_direct_max_irq);
+	seq_printf(m, "%*ssize:   %u\n", ind + 1, "", d->revmap_size);
 	seq_printf(m, "%*smapped: %u\n", ind + 1, "", d->mapcount);
 	seq_printf(m, "%*sflags:  0x%08x\n", ind +1 , "", d->flags);
 	if (d->ops && d->ops->debug_show)
-- 
2.30.2