The PCI specifications says that an I/O region must be aligned on a 4
KB boundary, and a memory region aligned on a 1 MB boundary.
However, the Marvell PCIe interfaces rely on address decoding windows
(which allow to associate a range of physical addresses with a given
device), and those have special requirements compared to the standard
PCI-to-PCI bridge specifications.
PCIe memory windows must have a power of two size (which matches the
PCI spec), be at least of 1 MB (which matches the PCI spec), and be
aligned on their size (which does not match the PCI spec, that
requires only a 1 MB alignment).
PCIe I/O windows must have a power of two size (matches the PCI spec),
be at least of 64 KB (doesn't match the PCI spec, which requires only
a size of 4 KB), and be aligned on their size (doesn't match the PCI
spec).
The PCI core already calls pcibios_align_resource() in the ARM PCI
core, specifically for such purposes. So this patch extends the ARM
PCI core so that it calls a ->align_resource() hook registered by the
PCI driver, exactly like the existing ->map_irq() and ->swizzle()
hooks.
A particular PCI driver can register a align_resource() hook, and do
its own specific alignement, depending on the specific constraints of
the underlying hardware.
Following the earlier reviews of this patch, a few comments:
* Using numerical values is not possible since the alignment value is
not absolute, but depends on the size of the memory window or I/O
window. We therefore really need a function hook.
* Using window_alignment() doesn't work, because it doesn't allow to
adjust the starting address of the memory or I/O window, and we
don't have access to the size. The comment was that
->resource_align() would apply to all resources on all busses, but
in the new implementation of the Marvell-specific
->resource_align() hook we are careful to only apply the alignment
constraints on the specific bus that hosts the emulated PCI-to-PCI
bridges needed to operate the Marvell PCIe interfaces.
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@xxxxxxxxxxxxxxxxxx>
Cc: Russell King <linux@xxxxxxxxxxxxxxxx>
---
arch/arm/include/asm/mach/pci.h | 11 +++++++++++
arch/arm/kernel/bios32.c | 6 ++++++
2 files changed, 17 insertions(+)
diff --git a/arch/arm/include/asm/mach/pci.h b/arch/arm/include/asm/mach/pci.h
index 5cf2e97..7d2c3c8 100644
--- a/arch/arm/include/asm/mach/pci.h
+++ b/arch/arm/include/asm/mach/pci.h
@@ -30,6 +30,11 @@ struct hw_pci {
void (*postinit)(void);
u8 (*swizzle)(struct pci_dev *dev, u8 *pin);
int (*map_irq)(const struct pci_dev *dev, u8 slot, u8 pin);
+ resource_size_t (*align_resource)(struct pci_dev *dev,
+ const struct resource *res,
+ resource_size_t start,
+ resource_size_t size,
+ resource_size_t align);
};
/*
@@ -51,6 +56,12 @@ struct pci_sys_data {
u8 (*swizzle)(struct pci_dev *, u8 *);
/* IRQ mapping */
int (*map_irq)(const struct pci_dev *, u8, u8);
+ /* Resource alignement requirements */
+ resource_size_t (*align_resource)(struct pci_dev *dev,
+ const struct resource *res,
+ resource_size_t start,
+ resource_size_t size,
+ resource_size_t align);
void *private_data; /* platform controller private data */
};
diff --git a/arch/arm/kernel/bios32.c b/arch/arm/kernel/bios32.c
index 5401645..be2e6c9 100644
--- a/arch/arm/kernel/bios32.c
+++ b/arch/arm/kernel/bios32.c
@@ -462,6 +462,7 @@ static void __init pcibios_init_hw(struct hw_pci *hw, struct list_head *head)
sys->busnr = busnr;
sys->swizzle = hw->swizzle;
sys->map_irq = hw->map_irq;
+ sys->align_resource = hw->align_resource;
INIT_LIST_HEAD(&sys->resources);
if (hw->private_data)
@@ -574,6 +575,8 @@ char * __init pcibios_setup(char *str)
resource_size_t pcibios_align_resource(void *data, const struct resource *res,
resource_size_t size, resource_size_t align)
{
+ struct pci_dev *dev = data;
+ struct pci_sys_data *sys = dev->sysdata;
resource_size_t start = res->start;
if (res->flags & IORESOURCE_IO && start & 0x300)
@@ -581,6 +584,9 @@ resource_size_t pcibios_align_resource(void *data, const struct resource *res,
start = (start + align - 1) & ~(align - 1);
+ if (sys->align_resource)
+ return sys->align_resource(dev, res, start, size, align);
+
return start;
}
--
1.7.9.5
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