linux-kernel - [PATCH v3 6/7] Drivers: hv: vmbus: Get the IRQ number from DT

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Message-Id: <20240726225910.1912537-7-romank@linux.microsoft.com>
Date: Fri, 26 Jul 2024 15:59:09 -0700
From: Roman Kisel <romank@...ux.microsoft.com>
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Subject: [PATCH v3 6/7] Drivers: hv: vmbus: Get the IRQ number from DT

The VMBus driver uses ACPI for interrupt assignment on
arm64 hence it won't function in the VTL mode where only
DeviceTree can be used.

Update the VMBus driver to discover interrupt configuration
via DeviceTree and indicate DMA cache coherency.

Signed-off-by: Roman Kisel <romank@...ux.microsoft.com>
---
 drivers/hv/vmbus_drv.c | 49 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 49 insertions(+)

diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index 12a707ab73f8..7eee7caff5f6 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -2306,6 +2306,34 @@ static int vmbus_acpi_add(struct platform_device *pdev)
 }
 #endif
 
+static int __maybe_unused vmbus_set_irq(struct platform_device *pdev)
+{
+	struct irq_desc *desc;
+	int irq;
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq == 0) {
+		pr_err("VMBus interrupt mapping failure\n");
+		return -EINVAL;
+	}
+	if (irq < 0) {
+		pr_err("VMBus interrupt data can't be read from DeviceTree, error %d\n", irq);
+		return irq;
+	}
+
+	desc = irq_to_desc(irq);
+	if (!desc) {
+		pr_err("No interrupt descriptor for VMBus virq %d\n", irq);
+		return -ENODEV;
+	}
+
+	vmbus_irq = irq;
+	vmbus_interrupt = desc->irq_data.hwirq;
+	pr_debug("VMBus virq %d, hwirq %d\n", vmbus_irq, vmbus_interrupt);
+
+	return 0;
+}
+
 static int vmbus_device_add(struct platform_device *pdev)
 {
 	struct resource **cur_res = &hyperv_mmio;
@@ -2320,6 +2348,12 @@ static int vmbus_device_add(struct platform_device *pdev)
 	if (ret)
 		return ret;
 
+#ifndef HYPERVISOR_CALLBACK_VECTOR
+	ret = vmbus_set_irq(pdev);
+	if (ret)
+		return ret;
+#endif
+
 	for_each_of_range(&parser, &range) {
 		struct resource *res;
 
@@ -2338,6 +2372,21 @@ static int vmbus_device_add(struct platform_device *pdev)
 		cur_res = &res->sibling;
 	}
 
+	/*
+	 * Hyper-V always assumes DMA cache coherency, and the DMA subsystem
+	 * might default to 'not coherent' on some architectures.
+	 * Avoid high-cost cache coherency maintenance done by the CPU.
+	 */
+#if defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_DEVICE) || \
+	defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU) || \
+	defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU_ALL)
+
+	if (!of_property_read_bool(np, "dma-coherent"))
+		pr_warn("Assuming cache coherent DMA transactions, no 'dma-coherent' node supplied\n");
+	pdev->dev.dma_coherent = true;
+
+#endif
+
 	return ret;
 }
 
-- 
2.34.1