misc: pci_endpoint_test: Add support for PCITEST_IRQ_TYPE_AUTO

For PCITEST_MSI we really want to set PCITEST_SET_IRQTYPE explicitly
to PCITEST_IRQ_TYPE_MSI, since we want to test if MSI works.

For PCITEST_MSIX we really want to set PCITEST_SET_IRQTYPE explicitly
to PCITEST_IRQ_TYPE_MSIX, since we want to test if MSI works.

For PCITEST_LEGACY_IRQ we really want to set PCITEST_SET_IRQTYPE
explicitly to PCITEST_IRQ_TYPE_INTX, since we want to test if INTx
works.

However, for PCITEST_WRITE, PCITEST_READ, PCITEST_COPY, we really don't
care which IRQ type that is used, we just want to use a IRQ type that is
supported by the EPC.

The old behavior was to always use MSI for PCITEST_WRITE, PCITEST_READ,
PCITEST_COPY, was to always set IRQ type to MSI before doing the actual
test, however, there are EPC drivers that do not support MSI.

Add a new PCITEST_IRQ_TYPE_AUTO, that will use the CAPS register to see
which IRQ types the endpoint supports, and use one of the supported IRQ
types.

For backwards compatibility, if the endpoint does not expose any supported
IRQ type in the CAPS register, simply fallback to using MSI, as it was
unconditionally done before.

Signed-off-by: Niklas Cassel <cassel@kernel.org>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Link: https://lore.kernel.org/r/20250310111016.859445-16-cassel@kernel.org

1 files changed, 20 insertions, 5 deletions

diff --git a/drivers/misc/pci_endpoint_test.c b/drivers/misc/pci_endpoint_test.c
index abcf1d91de37..1b57850dea9f 100644
--- a/drivers/misc/pci_endpoint_test.c
+++ b/drivers/misc/pci_endpoint_test.c
@@ -66,6 +66,9 @@
 
 #define PCI_ENDPOINT_TEST_CAPS			0x30
 #define CAP_UNALIGNED_ACCESS			BIT(0)
+#define CAP_MSI					BIT(1)
+#define CAP_MSIX				BIT(2)
+#define CAP_INTX				BIT(3)
 
 #define PCI_DEVICE_ID_TI_AM654			0xb00c
 #define PCI_DEVICE_ID_TI_J7200			0xb00f
@@ -113,6 +116,7 @@ struct pci_endpoint_test {
 	struct miscdevice miscdev;
 	enum pci_barno test_reg_bar;
 	size_t alignment;
+	u32 ep_caps;
 	const char *name;
 };
 
@@ -803,11 +807,23 @@ static int pci_endpoint_test_set_irq(struct pci_endpoint_test *test,
 	int ret;
 
 	if (req_irq_type < PCITEST_IRQ_TYPE_INTX ||
-	    req_irq_type > PCITEST_IRQ_TYPE_MSIX) {
+	    req_irq_type > PCITEST_IRQ_TYPE_AUTO) {
 		dev_err(dev, "Invalid IRQ type option\n");
 		return -EINVAL;
 	}
 
+	if (req_irq_type == PCITEST_IRQ_TYPE_AUTO) {
+		if (test->ep_caps & CAP_MSI)
+			req_irq_type = PCITEST_IRQ_TYPE_MSI;
+		else if (test->ep_caps & CAP_MSIX)
+			req_irq_type = PCITEST_IRQ_TYPE_MSIX;
+		else if (test->ep_caps & CAP_INTX)
+			req_irq_type = PCITEST_IRQ_TYPE_INTX;
+		else
+			/* fallback to MSI if no caps defined */
+			req_irq_type = PCITEST_IRQ_TYPE_MSI;
+	}
+
 	if (test->irq_type == req_irq_type)
 		return 0;
 
@@ -893,13 +909,12 @@ static void pci_endpoint_test_get_capabilities(struct pci_endpoint_test *test)
 {
 	struct pci_dev *pdev = test->pdev;
 	struct device *dev = &pdev->dev;
-	u32 caps;
 
-	caps = pci_endpoint_test_readl(test, PCI_ENDPOINT_TEST_CAPS);
-	dev_dbg(dev, "PCI_ENDPOINT_TEST_CAPS: %#x\n", caps);
+	test->ep_caps = pci_endpoint_test_readl(test, PCI_ENDPOINT_TEST_CAPS);
+	dev_dbg(dev, "PCI_ENDPOINT_TEST_CAPS: %#x\n", test->ep_caps);
 
 	/* CAP_UNALIGNED_ACCESS is set if the EP can do unaligned access */
-	if (caps & CAP_UNALIGNED_ACCESS)
+	if (test->ep_caps & CAP_UNALIGNED_ACCESS)
 		test->alignment = 0;
 }