misc: pci_endpoint_test: Add doorbell test case

Add doorbell support with the help of three new registers:
PCIE_ENDPOINT_TEST_DB_BAR, PCIE_ENDPOINT_TEST_DB_ADDR, and
PCIE_ENDPOINT_TEST_DB_DATA.

The testcase works by triggering the doorbell in Endpoint by writing the
value from PCI_ENDPOINT_TEST_DB_DATA register to the address provided by
PCI_ENDPOINT_TEST_DB_OFFSET register of the BAR indicated by the
PCIE_ENDPOINT_TEST_DB_BAR register and waiting for the completion status
from the Endpoint.

Signed-off-by: Frank Li <Frank.Li@nxp.com>
[mani: removed one spurious change and reworded the commit message]
Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Tested-by: Niklas Cassel <cassel@kernel.org>
Link: https://patch.msgid.link/20250710-ep-msi-v21-7-57683fc7fb25@nxp.com

Author: nxpfrankli

drivers/misc/pci_endpoint_test.c

@@ -37,6 +37,8 @@
 #define COMMAND_READ				BIT(3)
 #define COMMAND_WRITE				BIT(4)
 #define COMMAND_COPY				BIT(5)
+#define COMMAND_ENABLE_DOORBELL			BIT(6)
+#define COMMAND_DISABLE_DOORBELL		BIT(7)
 
 #define PCI_ENDPOINT_TEST_STATUS		0x8
 #define STATUS_READ_SUCCESS			BIT(0)
@@ -48,6 +50,11 @@
 #define STATUS_IRQ_RAISED			BIT(6)
 #define STATUS_SRC_ADDR_INVALID			BIT(7)
 #define STATUS_DST_ADDR_INVALID			BIT(8)
+#define STATUS_DOORBELL_SUCCESS			BIT(9)
+#define STATUS_DOORBELL_ENABLE_SUCCESS		BIT(10)
+#define STATUS_DOORBELL_ENABLE_FAIL		BIT(11)
+#define STATUS_DOORBELL_DISABLE_SUCCESS		BIT(12)
+#define STATUS_DOORBELL_DISABLE_FAIL		BIT(13)
 
 #define PCI_ENDPOINT_TEST_LOWER_SRC_ADDR	0x0c
 #define PCI_ENDPOINT_TEST_UPPER_SRC_ADDR	0x10
@@ -62,6 +69,7 @@
 #define PCI_ENDPOINT_TEST_IRQ_NUMBER		0x28
 
 #define PCI_ENDPOINT_TEST_FLAGS			0x2c
+
 #define FLAG_USE_DMA				BIT(0)
 
 #define PCI_ENDPOINT_TEST_CAPS			0x30
@@ -70,6 +78,10 @@
 #define CAP_MSIX				BIT(2)
 #define CAP_INTX				BIT(3)
 
+#define PCI_ENDPOINT_TEST_DB_BAR		0x34
+#define PCI_ENDPOINT_TEST_DB_OFFSET		0x38
+#define PCI_ENDPOINT_TEST_DB_DATA		0x3c
+
 #define PCI_DEVICE_ID_TI_AM654			0xb00c
 #define PCI_DEVICE_ID_TI_J7200			0xb00f
 #define PCI_DEVICE_ID_TI_AM64			0xb010
@@ -100,6 +112,7 @@ enum pci_barno {
 	BAR_3,
 	BAR_4,
 	BAR_5,
+	NO_BAR = -1,
 };
 
 struct pci_endpoint_test {
@@ -841,6 +854,73 @@ static int pci_endpoint_test_set_irq(struct pci_endpoint_test *test,
 	return 0;
 }
 
+static int pci_endpoint_test_doorbell(struct pci_endpoint_test *test)
+{
+	struct pci_dev *pdev = test->pdev;
+	struct device *dev = &pdev->dev;
+	int irq_type = test->irq_type;
+	enum pci_barno bar;
+	u32 data, status;
+	u32 addr;
+	int left;
+
+	if (irq_type < PCITEST_IRQ_TYPE_INTX ||
+	    irq_type > PCITEST_IRQ_TYPE_MSIX) {
+		dev_err(dev, "Invalid IRQ type\n");
+		return -EINVAL;
+	}
+
+	pci_endpoint_test_writel(test, PCI_ENDPOINT_TEST_IRQ_TYPE, irq_type);
+	pci_endpoint_test_writel(test, PCI_ENDPOINT_TEST_IRQ_NUMBER, 1);
+	pci_endpoint_test_writel(test, PCI_ENDPOINT_TEST_COMMAND,
+				 COMMAND_ENABLE_DOORBELL);
+
+	left = wait_for_completion_timeout(&test->irq_raised, msecs_to_jiffies(1000));
+
+	status = pci_endpoint_test_readl(test, PCI_ENDPOINT_TEST_STATUS);
+	if (!left || (status & STATUS_DOORBELL_ENABLE_FAIL)) {
+		dev_err(dev, "Failed to enable doorbell\n");
+		return -EINVAL;
+	}
+
+	data = pci_endpoint_test_readl(test, PCI_ENDPOINT_TEST_DB_DATA);
+	addr = pci_endpoint_test_readl(test, PCI_ENDPOINT_TEST_DB_OFFSET);
+	bar = pci_endpoint_test_readl(test, PCI_ENDPOINT_TEST_DB_BAR);
+
+	pci_endpoint_test_writel(test, PCI_ENDPOINT_TEST_IRQ_TYPE, irq_type);
+	pci_endpoint_test_writel(test, PCI_ENDPOINT_TEST_IRQ_NUMBER, 1);
+
+	pci_endpoint_test_writel(test, PCI_ENDPOINT_TEST_STATUS, 0);
+
+	bar = pci_endpoint_test_readl(test, PCI_ENDPOINT_TEST_DB_BAR);
+
+	writel(data, test->bar[bar] + addr);
+
+	left = wait_for_completion_timeout(&test->irq_raised, msecs_to_jiffies(1000));
+
+	status = pci_endpoint_test_readl(test, PCI_ENDPOINT_TEST_STATUS);
+
+	if (!left || !(status & STATUS_DOORBELL_SUCCESS))
+		dev_err(dev, "Failed to trigger doorbell in endpoint\n");
+
+	pci_endpoint_test_writel(test, PCI_ENDPOINT_TEST_COMMAND,
+				 COMMAND_DISABLE_DOORBELL);
+
+	wait_for_completion_timeout(&test->irq_raised, msecs_to_jiffies(1000));
+
+	status |= pci_endpoint_test_readl(test, PCI_ENDPOINT_TEST_STATUS);
+
+	if (status & STATUS_DOORBELL_DISABLE_FAIL) {
+		dev_err(dev, "Failed to disable doorbell\n");
+		return -EINVAL;
+	}
+
+	if (!(status & STATUS_DOORBELL_SUCCESS))
+		return -EINVAL;
+
+	return 0;
+}
+
 static long pci_endpoint_test_ioctl(struct file *file, unsigned int cmd,
 				    unsigned long arg)
 {
@@ -891,6 +971,9 @@ static long pci_endpoint_test_ioctl(struct file *file, unsigned int cmd,
 	case PCITEST_CLEAR_IRQ:
 		ret = pci_endpoint_test_clear_irq(test);
 		break;
+	case PCITEST_DOORBELL:
+		ret = pci_endpoint_test_doorbell(test);
+		break;
 	}
 
 ret:

include/uapi/linux/pcitest.h

@@ -21,6 +21,7 @@
 #define PCITEST_SET_IRQTYPE	_IOW('P', 0x8, int)
 #define PCITEST_GET_IRQTYPE	_IO('P', 0x9)
 #define PCITEST_BARS		_IO('P', 0xa)
+#define PCITEST_DOORBELL	_IO('P', 0xb)
 #define PCITEST_CLEAR_IRQ	_IO('P', 0x10)
 
 #define PCITEST_IRQ_TYPE_UNDEFINED	-1