[1/5] pci: weak function returns alignment

Commit Message

Gavin Shan Sept. 7, 2012, 5 a.m. UTC

The patch implements the weak function to return the default I/O
or memory alignment for P2P bridge. Currently, I/O window has 4KiB
or 1KiB alignment and memory window is 4MiB aligned by default. On
the other hand, those platforms (e.g. powernv) that have special
requirements on the alignment could override the function by themselves.

Signed-off-by: Gavin Shan <[e-mail]>
---
 drivers/pci/setup-bus.c |   32 ++++++++++++++++++++++++++++++++
 include/linux/pci.h     |    2 ++
 2 files changed, 34 insertions(+), 0 deletions(-)

Patch

diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
index fb50613..896f06e 100644
--- a/drivers/pci/setup-bus.c
+++ b/drivers/pci/setup-bus.c
@@ -697,6 +697,38 @@  static resource_size_t calculate_memsize(resource_size_t size,
 	return size;
 }
 
+resource_size_t __weak pcibios_window_alignment(struct pci_bus *bus,
+						unsigned long type)
+{
+	return 1;
+}
+
+#define PCI_P2P_DEFAULT_MEM_ALIGN	0x100000	/* 1MiB */
+#define PCI_P2P_DEFAULT_IO_ALIGN	0x1000		/* 4KiB */
+#define PCI_P2P_DEFAULT_IO_ALIGN_1K	0x400		/* 1KiB */
+
+static resource_size_t window_alignment(struct pci_bus *bus,
+					unsigned long type)
+{
+	resource_size_t align = 1, arch_align;
+
+	if (type & IORESOURCE_MEM)
+		align = PCI_P2P_DEFAULT_MEM_ALIGN;
+	else if (type & IORESOURCE_IO) {
+		/*
+		 * Per spec, I/O windows are 4K-aligned, but some
+		 * bridges have an extension to support 1K alignment.
+		 */
+		if (bus->self->io_window_1k)
+			align = PCI_P2P_DEFAULT_IO_ALIGN_1K;
+		else
+			align = PCI_P2P_DEFAULT_IO_ALIGN;
+	}
+
+	arch_align = pcibios_window_alignment(bus, type);
+	return max(align, arch_align);
+}
+
 /**
  * pbus_size_io() - size the io window of a given bus
  *
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 5faa831..e4e4794 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1031,6 +1031,8 @@  int pci_cfg_space_size_ext(struct pci_dev *dev);
 int pci_cfg_space_size(struct pci_dev *dev);
 unsigned char pci_bus_max_busnr(struct pci_bus *bus);
 void pci_setup_bridge(struct pci_bus *bus);
+resource_size_t pcibios_window_alignment(struct pci_bus *bus,
+					 unsigned long type);
 
 #define PCI_VGA_STATE_CHANGE_BRIDGE (1 << 0)
 #define PCI_VGA_STATE_CHANGE_DECODES (1 << 1)