[PATCH v4 1/2] genirq/msi: add wrapper msi allocation API and export msi functions

[Nipun Gupta <nipun.gupta@amd.com>]

MSI functions can be for allocation and free can be directly
used by the device drivers without any wrapper provided by
bus drivers. So export these MSI functions.

Also, add a wrapper API to allocate MSIs providing only the
number of IRQ's rather than range for simpler driver usage.

Signed-off-by: Nipun Gupta <nipun.gupta@amd.com>
---

Changes in v3->v4:
- No change

Changes in v3:
- New in this patch series. VFIO-CDX uses the new wrapper API
  msi_domain_alloc_irqs and exported APIs. (This patch is moved
  from CDX interrupt support to vfio-cdx patch, where these APIs
  are used).

 include/linux/msi.h | 6 ++++++
 kernel/irq/msi.c    | 2 ++
 2 files changed, 8 insertions(+)

diff --git a/include/linux/msi.h b/include/linux/msi.h
index ddace8c34dcf..a9f77cbc8847 100644
--- a/include/linux/msi.h
+++ b/include/linux/msi.h
@@ -658,6 +658,12 @@ void platform_msi_device_domain_free(struct irq_domain *domain, unsigned int vir
 void *platform_msi_get_host_data(struct irq_domain *domain);
 
 bool msi_device_has_isolated_msi(struct device *dev);
+
+static inline int msi_domain_alloc_irqs(struct device *dev, unsigned int domid, int nirqs)
+{
+	return msi_domain_alloc_irqs_range(dev, domid, 0, nirqs - 1);
+}
+
 #else /* CONFIG_GENERIC_MSI_IRQ */
 static inline bool msi_device_has_isolated_msi(struct device *dev)
 {
diff --git a/kernel/irq/msi.c b/kernel/irq/msi.c
index 79b4a58ba9c3..4a324f683858 100644
--- a/kernel/irq/msi.c
+++ b/kernel/irq/msi.c
@@ -1404,6 +1404,7 @@ int msi_domain_alloc_irqs_range(struct device *dev, unsigned int domid,
 	msi_unlock_descs(dev);
 	return ret;
 }
+EXPORT_SYMBOL_GPL(msi_domain_alloc_irqs_range);
 
 /**
  * msi_domain_alloc_irqs_all_locked - Allocate all interrupts from a MSI interrupt domain
@@ -1596,6 +1597,7 @@ void msi_domain_free_irqs_range(struct device *dev, unsigned int domid,
 	msi_domain_free_irqs_range_locked(dev, domid, first, last);
 	msi_unlock_descs(dev);
 }
+EXPORT_SYMBOL_GPL(msi_domain_free_irqs_all);
 
 /**
  * msi_domain_free_irqs_all_locked - Free all interrupts from a MSI interrupt domain
-- 
2.34.1