[patch V2 05/31] genirq/msi: Provide msi_alloc_msi_desc() and a simple allocator

[Thomas Gleixner <tglx@xxxxxxxxxxxxx>]

Provide msi_alloc_msi_desc() which takes a template MSI descriptor for
initializing a newly allocated descriptor. This allows to simplify various
usage sites of alloc_msi_entry() and moves the storage handling into the
core code.

For simple cases where only a linear vector space is required provide
msi_add_simple_msi_descs() which just allocates a linear range of MSI
descriptors and fills msi_desc::msi_index accordingly.

Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
---
 include/linux/msi.h |    2 +
 kernel/irq/msi.c    |   59 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 61 insertions(+)

--- a/include/linux/msi.h
+++ b/include/linux/msi.h
@@ -264,6 +264,8 @@ static inline void pci_write_msi_msg(uns
 }
 #endif /* CONFIG_PCI_MSI */
 
+int msi_add_msi_desc(struct device *dev, struct msi_desc *init_desc);
+
 struct msi_desc *alloc_msi_entry(struct device *dev, int nvec,
                                 const struct irq_affinity_desc *affinity);
 void free_msi_entry(struct msi_desc *entry);
--- a/kernel/irq/msi.c
+++ b/kernel/irq/msi.c
@@ -61,6 +61,65 @@ void free_msi_entry(struct msi_desc *ent
 }
 
 /**
+ * msi_add_msi_desc - Allocate and initialize a MSI descriptor
+ * @dev:       Pointer to the device for which the descriptor is allocated
+ * @init_desc: Pointer to an MSI descriptor to initialize the new descriptor
+ *
+ * Return: 0 on success or an appropriate failure code.
+ */
+int msi_add_msi_desc(struct device *dev, struct msi_desc *init_desc)
+{
+       struct msi_desc *desc;
+
+       lockdep_assert_held(&dev->msi.data->mutex);
+
+       desc = alloc_msi_entry(dev, init_desc->nvec_used, init_desc->affinity);
+       if (!desc)
+               return -ENOMEM;
+
+       /* Copy the MSI index and type specific data to the new descriptor. */
+       desc->msi_index = init_desc->msi_index;
+       desc->pci = init_desc->pci;
+
+       list_add_tail(&desc->list, &dev->msi.data->list);
+       return 0;
+}
+
+/**
+ * msi_add_simple_msi_descs - Allocate and initialize MSI descriptors
+ * @dev:       Pointer to the device for which the descriptors are allocated
+ * @index:     Index for the first MSI descriptor
+ * @ndesc:     Number of descriptors to allocate
+ *
+ * Return: 0 on success or an appropriate failure code.
+ */
+static int msi_add_simple_msi_descs(struct device *dev, unsigned int index, 
unsigned int ndesc)
+{
+       struct msi_desc *desc, *tmp;
+       LIST_HEAD(list);
+       unsigned int i;
+
+       lockdep_assert_held(&dev->msi.data->mutex);
+
+       for (i = 0; i < ndesc; i++) {
+               desc = alloc_msi_entry(dev, 1, NULL);
+               if (!desc)
+                       goto fail;
+               desc->msi_index = index + i;
+               list_add_tail(&desc->list, &list);
+       }
+       list_splice_tail(&list, &dev->msi.data->list);
+       return 0;
+
+fail:
+       list_for_each_entry_safe(desc, tmp, &list, list) {
+               list_del(&desc->list);
+               free_msi_entry(desc);
+       }
+       return -ENOMEM;
+}
+
+/**
  * msi_device_set_properties - Set device specific MSI properties
  * @dev:       Pointer to the device which is queried
  * @prop:      Properties to set