PCI: endpoint: Add support to specify alignment for buffers allocated to BARs

The address that is allocated using pci_epf_alloc_space() is
directly written to the target address of the Inbound Address
Translation unit (ie the HW component implementing inbound address
decoding) on endpoint controllers.

Designware IP [1] has a configuration parameter (CX_ATU_MIN_REGION_SIZE
[2]) which has 64KB as default value and the lower 16 bits of the Base,
Limit and Target registers of the Inbound ATU are fixed to zero. If the
programmed memory address is not aligned to 64 KB boundary this causes
memory corruption.

Modify pci_epf_alloc_space() API to take alignment size as argument in
order to allocate buffers to be mapped to BARs with an alignment that
suits the platform where they are used.

Add an 'align' parameter to epc_features which can be used by platform
drivers to specify the BAR allocation alignment requirements and use
this while invoking pci_epf_alloc_space().

[1] "I/O and MEM Match Modes" section in DesignWare Cores PCI Express
     Controller Databook version 4.90a
[2]  http://www.ti.com/lit/ug/spruid7c/spruid7c.pdf

Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/include/linux/pci-epf.h b/include/linux/pci-epf.h
index ec02f58758c8..2d6f07556682 100644
--- a/include/linux/pci-epf.h
+++ b/include/linux/pci-epf.h
@@ -149,7 +149,8 @@ void pci_epf_destroy(struct pci_epf *epf);
 int __pci_epf_register_driver(struct pci_epf_driver *driver,
 			      struct module *owner);
 void pci_epf_unregister_driver(struct pci_epf_driver *driver);
-void *pci_epf_alloc_space(struct pci_epf *epf, size_t size, enum pci_barno bar);
+void *pci_epf_alloc_space(struct pci_epf *epf, size_t size, enum pci_barno bar,
+			  size_t align);
 void pci_epf_free_space(struct pci_epf *epf, void *addr, enum pci_barno bar);
 int pci_epf_bind(struct pci_epf *epf);
 void pci_epf_unbind(struct pci_epf *epf);