[PATCH v2 3/7] of/irq: Break out msi-map lookup (again)

On Tue, Jun 14, 2016 at 07:12:46PM +0100, Robin Murphy wrote:

On 14/06/16 15:37, Will Deacon wrote:

quoted

On Fri, Jun 03, 2016 at 06:15:38PM +0100, Robin Murphy wrote:

quoted

The PCI msi-map code is already doing double-duty translating IDs and
retrieving MSI parents, which unsurprisingly is the same functionality
we need for the identically-formatted PCI iommu-map property. Drag the
core parsing routine up yet another layer into the general OF-PCI code,
and further generalise it for either kind of lookup in either flavour
of map property.

CC: Rob Herring <robh+dt@kernel.org>
CC: Frank Rowand <redacted>
CC: Marc Zyngier <redacted>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
---

v2: No change.

 drivers/of/irq.c       |  70 ++-------------------------------
 drivers/of/of_pci.c    | 102 +++++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/of_pci.h |   8 ++++
 3 files changed, 114 insertions(+), 66 deletions(-)

[...]

quoted

diff --git a/drivers/of/of_pci.c b/drivers/of/of_pci.c
index 13f4fed38048..20bf5a0c57fd 100644
--- a/drivers/of/of_pci.c
+++ b/drivers/of/of_pci.c

@@ -306,3 +306,105 @@ struct msi_controller *of_pci_find_msi_chip_by_node(struct device_node *of_node)
 EXPORT_SYMBOL_GPL(of_pci_find_msi_chip_by_node);

 #endif /* CONFIG_PCI_MSI */
+
+#define MASK_NAME_LEN	32	/* Safely longer than "iommu-map-mask" */
+
+/**
+ * of_pci_map_rid - Translate a requester ID through a downstream mapping.
+ * @np: root complex device node.
+ * @map_name: property name of the map to use.
+ * @target: optional pointer to a target device node.
+ * @id_out: optional pointer to receive the translated ID.
+ *
+ * Given a PCI requester ID, look up the appropriate implementation-defined
+ * platform ID and/or the target device which receives transactions on that
+ * ID, as per the "iommu-map" and "msi-map" bindings. @target or @id_out may
+ * be NULL if not required. If @target points to a device node pointer, only
+ * entries targeting that node will be matched; if it points to a NULL
+ * value, it will receive the device node for the first matching target entry,
+ * with a reference held.
+ *
+ * Return: 0 on success or a standard error code on failure.
+ */
+int of_pci_map_rid(struct device_node *np, const char *map_name, u32 rid_in,
+		   struct device_node **target, u32 *rid_out)
+{
+	u32 map_mask, masked_rid;
+	int map_len;
+	const __be32 *map = NULL;
+	char mask_name[MASK_NAME_LEN];

Couldn't you avoid this if you just took const char *mask_name as a
parameter too?

Having started out with that, I considered two strings essentially
duplicating each other, possibly duplicated per callsite, and thought it
might be prudent to trade off a little runtime work for a permanent
reduction in static data. I like the "never save anything you can
recalculate" philosophy, but it is possible I got a bit carried away here.
If you hate it I can just add the extra argument back.

Yeah, please do. The idea is that this can be used with different bindings,
and I don't think we gain anything from constructing the mask string other
than and ugliness complexity.

Will