PCI/MSI: Move pci_enable_msix_range() to api.c

To disentangle the maze in msi.c, all exported device-driver MSI APIs are
now to be grouped in one file, api.c.

Move pci_enable_msix_range() and make its kernel-doc comprehensive.
Signed-off-by: Ahmed S. Darwish <darwi@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Link: https://lore.kernel.org/r/20221111122014.813792885@linutronix.de

drivers/pci/msi/api.c

@@ -58,3 +58,35 @@ void pci_disable_msi(struct pci_dev *dev)
 	msi_unlock_descs(&dev->dev);
 }
 EXPORT_SYMBOL(pci_disable_msi);
+
+/**
+ * pci_enable_msix_range() - Enable MSI-X interrupt mode on device
+ * @dev:     the PCI device to operate on
+ * @entries: input/output parameter, array of MSI-X configuration entries
+ * @minvec:  minimum required number of MSI-X vectors
+ * @maxvec:  maximum desired number of MSI-X vectors
+ *
+ * Legacy device driver API to enable MSI-X interrupt mode on device and
+ * configure its MSI-X capability structure as appropriate.  The passed
+ * @entries array must have each of its members "entry" field set to a
+ * desired (valid) MSI-X vector number, where the range of valid MSI-X
+ * vector numbers can be queried through pci_msix_vec_count().  If
+ * successful, the driver must invoke pci_disable_msix() on cleanup.
+ *
+ * NOTE: The newer pci_alloc_irq_vectors() / pci_free_irq_vectors() API
+ * pair should, in general, be used instead.
+ *
+ * Return: number of MSI-X vectors allocated (which might be smaller
+ * than @maxvecs), where Linux IRQ numbers for such allocated vectors
+ * are saved back in the @entries array elements' "vector" field. Return
+ * -ENOSPC if less than @minvecs interrupt vectors are available.
+ * Return -EINVAL if one of the passed @entries members "entry" field
+ * was invalid or a duplicate, or if plain MSI interrupts mode was
+ * earlier enabled on device. Return other errnos otherwise.
+ */
+int pci_enable_msix_range(struct pci_dev *dev, struct msix_entry *entries,
+			  int minvec, int maxvec)
+{
+	return __pci_enable_msix_range(dev, entries, minvec, maxvec, NULL, 0);
+}
+EXPORT_SYMBOL(pci_enable_msix_range);

drivers/pci/msi/msi.c

@@ -844,10 +844,10 @@ int __pci_enable_msi_range(struct pci_dev *dev, int minvec, int maxvec,
 	}
 }
 
-static int __pci_enable_msix_range(struct pci_dev *dev,
-				   struct msix_entry *entries, int minvec,
-				   int maxvec, struct irq_affinity *affd,
-				   int flags)
+int __pci_enable_msix_range(struct pci_dev *dev,
+			    struct msix_entry *entries, int minvec,
+			    int maxvec, struct irq_affinity *affd,
+			    int flags)
 {
 	int rc, nvec = maxvec;
 
@@ -886,28 +886,6 @@ static int __pci_enable_msix_range(struct pci_dev *dev,
 	}
 }
 
-/**
- * pci_enable_msix_range - configure device's MSI-X capability structure
- * @dev: pointer to the pci_dev data structure of MSI-X device function
- * @entries: pointer to an array of MSI-X entries
- * @minvec: minimum number of MSI-X IRQs requested
- * @maxvec: maximum number of MSI-X IRQs requested
- *
- * Setup the MSI-X capability structure of device function with a maximum
- * possible number of interrupts in the range between @minvec and @maxvec
- * upon its software driver call to request for MSI-X mode enabled on its
- * hardware device function. It returns a negative errno if an error occurs.
- * If it succeeds, it returns the actual number of interrupts allocated and
- * indicates the successful configuration of MSI-X capability structure
- * with new allocated MSI-X interrupts.
- **/
-int pci_enable_msix_range(struct pci_dev *dev, struct msix_entry *entries,
-		int minvec, int maxvec)
-{
-	return __pci_enable_msix_range(dev, entries, minvec, maxvec, NULL, 0);
-}
-EXPORT_SYMBOL(pci_enable_msix_range);
-
 /**
  * pci_alloc_irq_vectors_affinity - allocate multiple IRQs for a device
  * @dev:		PCI device to operate on

drivers/pci/msi/msi.h

@@ -88,8 +88,11 @@ static inline __attribute_const__ u32 msi_multi_mask(struct msi_desc *desc)
 void pci_msi_shutdown(struct pci_dev *dev);
 void pci_free_msi_irqs(struct pci_dev *dev);
 int __pci_enable_msi_range(struct pci_dev *dev, int minvec, int maxvec, struct irq_affinity *affd);
+int __pci_enable_msix_range(struct pci_dev *dev, struct msix_entry *entries, int minvec,
+			    int maxvec,  struct irq_affinity *affd, int flags);
 
 /* Legacy (!IRQDOMAIN) fallbacks */
+
 #ifdef CONFIG_PCI_MSI_ARCH_FALLBACKS
 int pci_msi_legacy_setup_msi_irqs(struct pci_dev *dev, int nvec, int type);
 void pci_msi_legacy_teardown_msi_irqs(struct pci_dev *dev);