PCI: endpoint: pci-epf-test: Add support for capabilities

The test BAR is on the EP side is allocated using pci_epf_alloc_space(),
which allocates the backing memory using dma_alloc_coherent(), which will
return zeroed memory regardless of __GFP_ZERO was set or not.

This means that running a new version of pci-endpoint-test.c (host side)
with an old version of pci-epf-test.c (EP side) will not see any
capabilities being set (as intended), so this is backwards compatible.

Additionally, the EP side always allocates at least 128 bytes for the test
BAR (excluding the MSI-X table), this means that adding another register at
offset 0x30 is still within the 128 available bytes.

For now, we only add the CAP_UNALIGNED_ACCESS capability.

Set CAP_UNALIGNED_ACCESS if the EPC driver can handle any address (because
it implements the .align_addr callback).

Link: https://lore.kernel.org/r/20241203063851.695733-5-cassel@kernel.org
Signed-off-by: Niklas Cassel <cassel@kernel.org>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Reviewed-by: Frank Li <Frank.Li@nxp.com>

diff --git a/drivers/pci/endpoint/functions/pci-epf-test.c b/drivers/pci/endpoint/functions/pci-epf-test.c
index b2fdd8c82c438700a3418b7fd4ef0fc1f892d49c..b94e205ae10b94c33c7a2c4f38f6c38e1f94443a 100644 (file)
--- a/drivers/pci/endpoint/functions/pci-epf-test.c
+++ b/drivers/pci/endpoint/functions/pci-epf-test.c
@@ -44,6 +44,8 @@
 
 #define TIMER_RESOLUTION               1
 
+#define CAP_UNALIGNED_ACCESS           BIT(0)
+
 static struct workqueue_struct *kpcitest_workqueue;
 
 struct pci_epf_test {
@@ -74,6 +76,7 @@ struct pci_epf_test_reg {
        u32     irq_type;
        u32     irq_number;
        u32     flags;
+       u32     caps;
 } __packed;
 
 static struct pci_epf_header test_header = {
@@ -739,6 +742,20 @@ static void pci_epf_test_clear_bar(struct pci_epf *epf)
        }
 }
 
+static void pci_epf_test_set_capabilities(struct pci_epf *epf)
+{
+       struct pci_epf_test *epf_test = epf_get_drvdata(epf);
+       enum pci_barno test_reg_bar = epf_test->test_reg_bar;
+       struct pci_epf_test_reg *reg = epf_test->reg[test_reg_bar];
+       struct pci_epc *epc = epf->epc;
+       u32 caps = 0;
+
+       if (epc->ops->align_addr)
+               caps |= CAP_UNALIGNED_ACCESS;
+
+       reg->caps = cpu_to_le32(caps);
+}
+
 static int pci_epf_test_epc_init(struct pci_epf *epf)
 {
        struct pci_epf_test *epf_test = epf_get_drvdata(epf);
@@ -763,6 +780,8 @@ static int pci_epf_test_epc_init(struct pci_epf *epf)
                }
        }
 
+       pci_epf_test_set_capabilities(epf);
+
        ret = pci_epf_test_set_bar(epf);
        if (ret)
                return ret;