genirq/msi: Make the .prepare callback reusable

The .prepare callbacks are so far only called from msi_domain_alloc_irqs.
In order to reuse that code, split that code and create a
msi_domain_prepare_irqs function that the existing code can call into.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

2 files changed, 19 insertions, 3 deletions

diff --git a/include/linux/msi.h b/include/linux/msi.h
index f71a25e5fd25..1c0bb2c0b211 100644
--- a/include/linux/msi.h
+++ b/include/linux/msi.h
@@ -279,6 +279,10 @@ struct irq_domain *platform_msi_create_irq_domain(struct fwnode_handle *fwnode,
 int platform_msi_domain_alloc_irqs(struct device *dev, unsigned int nvec,
                                    irq_write_msi_msg_t write_msi_msg);
 void platform_msi_domain_free_irqs(struct device *dev);
+
+/* When an MSI domain is used as an intermediate domain */
+int msi_domain_prepare_irqs(struct irq_domain *domain, struct device *dev,
+                            int nvec, msi_alloc_info_t *args);
 #endif /* CONFIG_GENERIC_MSI_IRQ_DOMAIN */
 
 #ifdef CONFIG_PCI_MSI_IRQ_DOMAIN
diff --git a/kernel/irq/msi.c b/kernel/irq/msi.c
index 6b0c0b74a2a1..9a85613d4227 100644
--- a/kernel/irq/msi.c
+++ b/kernel/irq/msi.c
@@ -252,6 +252,20 @@ struct irq_domain *msi_create_irq_domain(struct fwnode_handle *fwnode,
                                            &msi_domain_ops, info);
 }
 
+int msi_domain_prepare_irqs(struct irq_domain *domain, struct device *dev,
+                            int nvec, msi_alloc_info_t *arg)
+{
+        struct msi_domain_info *info = domain->host_data;
+        struct msi_domain_ops *ops = info->ops;
+        int ret;
+
+        ret = ops->msi_check(domain, info, dev);
+        if (ret == 0)
+                ret = ops->msi_prepare(domain, dev, nvec, arg);
+
+        return ret;
+}
+
 /**
  * msi_domain_alloc_irqs - Allocate interrupts from a MSI interrupt domain
  * @domain:     The domain to allocate from
@@ -270,9 +284,7 @@ int msi_domain_alloc_irqs(struct irq_domain *domain, struct device *dev,
         struct msi_desc *desc;
         int i, ret, virq = -1;
 
-        ret = ops->msi_check(domain, info, dev);
-        if (ret == 0)
-                ret = ops->msi_prepare(domain, dev, nvec, &arg);
+        ret = msi_domain_prepare_irqs(domain, dev, nvec, &arg);
         if (ret)
                 return ret;