On Wed, Mar 25, 2015 at 04:07:43PM -0400, Konrad Rzeszutek Wilk wrote:
On Fri, Mar 20, 2015 at 04:17:55PM -0700, Luis R. Rodriguez wrote:
quoted
From: "Luis R. Rodriguez" <redacted>
This allows drivers to take advantage of write-combining
when possible. Ideally we'd have pci_read_bases() just
peg an IORESOURCE_WC flag for us but where exactly
video devices memory lie varies *largely* and at times things
are mixed with MMIO registers, sometimes we can address
the changes in drivers, other times the change requires
intrusive changes.
Although there is also arch_phys_wc_add() that makes use of
architecture specific write-combinging alternatives (MTRR on
combinging?
Amended.
quoted
diff --git a/lib/pci_iomap.c b/lib/pci_iomap.c
index bcce5f1..30b65ae 100644
--- a/lib/pci_iomap.c
+++ b/lib/pci_iomap.c
@@ -52,6 +52,46 @@ void __iomem *pci_iomap_range(struct pci_dev *dev,
EXPORT_SYMBOL(pci_iomap_range);
/**
+ * pci_iomap_wc_range - create a virtual WC mapping cookie for a PCI BAR
+ * @dev: PCI device that owns the BAR
+ * @bar: BAR number
+ * @offset: map memory at the given offset in BAR
+ * @maxlen: max length of the memory to map
+ *
+ * Using this function you will get a __iomem address to your device BAR.
+ * You can access it using ioread*() and iowrite*(). These functions hide
+ * the details if this is a MMIO or PIO address space and will just do what
+ * you expect from them in the correct way. When possible write combining
+ * is used.
+ *
+ * @maxlen specifies the maximum length to map. If you want to get access to
+ * the complete BAR from offset to the end, pass %0 here.
s/%0/0 ? Or is that some special syntax?
This copies the syntax of pci_iomap_range() which also uses %0, and as per
Documentation/kernel-doc-nano-HOWTO.txt % is used for constants. See:
scripts/kernel-doc -man -function pci_iomap_range lib/pci_iomap.c | nroff -man | less
Luis