[PATCH v18 09/15] PCI: endpoint: Add pci_epf_align_inbound_addr() helper for address alignment

Frank Li
2025-04-14T18:32:12Z

Introduce the helper function pci_epf_align_inbound_addr() to adjust
addresses according to PCI BAR alignment requirements, converting addresses
into base and offset values.

Signed-off-by: Frank Li <Frank.Li@nxp.com>
---
Change from v15 to v16
- none

Change from v14 to v15
- change out address type to dma_addr_t to fix below build issue

| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202502082311.G1hWGggF-lkp@intel.com/

All errors (new ones prefixed by >>):

drivers/pci/endpoint/functions/pci-epf-test.c: In function 'pci_epf_test_enable_doorbell':
>> drivers/pci/endpoint/functions/pci-epf-test.c:726:42: error: passing argument 4 of 'pci_epf_align_inbound_addr' from incompatible pointer type [-Werror=incompatible-pointer-types]
726 | &epf_test->db_bar.phys_addr, &offset);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~
| |
| dma_addr_t * {aka unsigned int *}
In file included from include/linux/pci-epc.h:12,

Change form v9 to v14
- none

change from v8 to v9
- pci_epf_align_inbound_addr(), base and off must be not NULL
- rm pci_epf_align_inbound_addr_lo_hi()

change from v7 to v8
- change name to pci_epf_align_inbound_addr()
- update comment said only need for memory, which not allocated by
pci_epf_alloc_space().

change from v6 to v7
- new patch
---
drivers/pci/endpoint/pci-epf-core.c | 44 +++++++++++++++++++++++++++++++++++++
include/linux/pci-epf.h | 3 +++
2 files changed, 47 insertions(+)

diff --git a/drivers/pci/endpoint/pci-epf-core.c b/drivers/pci/endpoint/pci-epf-core.c
index d04224b8e1631..529dbaaf76750 100644
--- a/drivers/pci/endpoint/pci-epf-core.c
+++ b/drivers/pci/endpoint/pci-epf-core.c
@@ -473,6 +473,50 @@ struct pci_epf *pci_epf_create(const char *name)
}
EXPORT_SYMBOL_GPL(pci_epf_create);

+/**
+ * pci_epf_align_inbound_addr() - Get base address and offset that match BAR's
+ * alignment requirement
+ * @epf: the EPF device
+ * @addr: the address of the memory
+ * @bar: the BAR number corresponding to map addr
+ * @base: return base address, which match BAR's alignment requirement.
+ * @off: return offset.
+ *
+ * Helper function to convert input 'addr' to base and offset, which match
+ * BAR's alignment requirement.
+ *
+ * The pci_epf_alloc_space() function already accounts for alignment. This is
+ * primarily intended for use with other memory regions not allocated by
+ * pci_epf_alloc_space(), such as peripheral register spaces or the trigger
+ * address for a platform MSI controller.
+ */
+int pci_epf_align_inbound_addr(struct pci_epf *epf, enum pci_barno bar,
+ u64 addr, dma_addr_t *base, size_t *off)
+{
+ const struct pci_epc_features *epc_features;
+ u64 align;
+
+ if (!base || !off)
+ return -EINVAL;
+
+ epc_features = pci_epc_get_features(epf->epc, epf->func_no, epf->vfunc_no);
+ if (!epc_features) {
+ dev_err(&epf->dev, "epc_features not implemented\n");
+ return -EOPNOTSUPP;
+ }
+
+ align = epc_features->align;
+ align = align ? align : 128;
+ if (epc_features->bar[bar].type == BAR_FIXED)
+ align = max(epc_features->bar[bar].fixed_size, align);
+
+ *base = round_down(addr, align);
+ *off = addr & (align - 1);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(pci_epf_align_inbound_addr);
+
static void pci_epf_dev_release(struct device *dev)
{
struct pci_epf *epf = to_pci_epf(dev);
diff --git a/include/linux/pci-epf.h b/include/linux/pci-epf.h
index dcc6e2a2c6b3c..299ce1f1e2d80 100644
--- a/include/linux/pci-epf.h
+++ b/include/linux/pci-epf.h
@@ -241,6 +241,9 @@ void *pci_epf_alloc_space(struct pci_epf *epf, size_t size, enum pci_barno bar,
enum pci_epc_interface_type type);
void pci_epf_free_space(struct pci_epf *epf, void *addr, enum pci_barno bar,
enum pci_epc_interface_type type);
+
+int pci_epf_align_inbound_addr(struct pci_epf *epf, enum pci_barno bar,
+ u64 addr, dma_addr_t *base, size_t *off);
int pci_epf_bind(struct pci_epf *epf);
void pci_epf_unbind(struct pci_epf *epf);
int pci_epf_add_vepf(struct pci_epf *epf_pf, struct pci_epf *epf_vf);

--
2.34.1