net/mlx5: Provide external API for allocating vectors

Provide external API to be used by other drivers relying on mlx5_core,
for allocating MSIX vectors. An example for such a driver would be
mlx5_vdpa.

Signed-off-by: Eli Cohen <elic@nvidia.com>
Reviewed-by: Shay Drory <shayd@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>

drivers/net/ethernet/mellanox/mlx5/core/pci_irq.c

@@ -483,6 +483,58 @@ struct mlx5_irq *mlx5_irq_request(struct mlx5_core_dev *dev, u16 vecidx,
 	return irq;
 }
 
+/**
+ * mlx5_msix_alloc - allocate msix interrupt
+ * @dev: mlx5 device from which to request
+ * @handler: interrupt handler
+ * @affdesc: affinity descriptor
+ * @name: interrupt name
+ *
+ * Returns: struct msi_map with result encoded.
+ * Note: the caller must make sure to release the irq by calling
+ *       mlx5_msix_free() if shutdown was initiated.
+ */
+struct msi_map mlx5_msix_alloc(struct mlx5_core_dev *dev,
+			       irqreturn_t (*handler)(int, void *),
+			       const struct irq_affinity_desc *affdesc,
+			       const char *name)
+{
+	struct msi_map map;
+	int err;
+
+	if (!dev->pdev) {
+		map.virq = 0;
+		map.index = -EINVAL;
+		return map;
+	}
+
+	map = pci_msix_alloc_irq_at(dev->pdev, MSI_ANY_INDEX, affdesc);
+	if (!map.virq)
+		return map;
+
+	err = request_irq(map.virq, handler, 0, name, NULL);
+	if (err) {
+		mlx5_core_warn(dev, "err %d\n", err);
+		pci_msix_free_irq(dev->pdev, map);
+		map.virq = 0;
+		map.index = -ENOMEM;
+	}
+	return map;
+}
+EXPORT_SYMBOL(mlx5_msix_alloc);
+
+/**
+ * mlx5_msix_free - free a previously allocated msix interrupt
+ * @dev: mlx5 device associated with interrupt
+ * @map: map previously returned by mlx5_msix_alloc()
+ */
+void mlx5_msix_free(struct mlx5_core_dev *dev, struct msi_map map)
+{
+	free_irq(map.virq, NULL);
+	pci_msix_free_irq(dev->pdev, map);
+}
+EXPORT_SYMBOL(mlx5_msix_free);
+
 /**
  * mlx5_irqs_release_vectors - release one or more IRQs back to the system.
  * @irqs: IRQs to be released.

include/linux/mlx5/driver.h

@@ -1308,4 +1308,10 @@ enum {
 	MLX5_OCTWORD = 16,
 };
 
+struct msi_map mlx5_msix_alloc(struct mlx5_core_dev *dev,
+			       irqreturn_t (*handler)(int, void *),
+			       const struct irq_affinity_desc *affdesc,
+			       const char *name);
+void mlx5_msix_free(struct mlx5_core_dev *dev, struct msi_map map);
+
 #endif /* MLX5_DRIVER_H */