Driver: VMBus: Add device tree support

Update the driver to support device tree boot as well along with ACPI.
At present the device tree parsing only provides the mmio region info
and is not the exact copy of ACPI parsing. This is sufficient to cater
all the current device tree usecases for VMBus.

Currently device tree is supported only for x86 systems.

Signed-off-by: Saurabh Sengar <ssengar@linux.microsoft.com>

drivers/hv/Kconfig

@@ -4,8 +4,8 @@ menu "Microsoft Hyper-V guest support"
 
 config HYPERV
 	tristate "Microsoft Hyper-V client drivers"
-	depends on ACPI && ((X86 && X86_LOCAL_APIC && HYPERVISOR_GUEST) \
-		|| (ARM64 && !CPU_BIG_ENDIAN))
+	depends on (X86 && X86_LOCAL_APIC && HYPERVISOR_GUEST) \
+		|| (ACPI && ARM64 && !CPU_BIG_ENDIAN)
 	select PARAVIRT
 	select X86_HV_CALLBACK_VECTOR if X86
 	select VMAP_PFN

drivers/hv/vmbus_drv.c

@@ -20,6 +20,7 @@
 #include <linux/completion.h>
 #include <linux/hyperv.h>
 #include <linux/kernel_stat.h>
+#include <linux/of_address.h>
 #include <linux/clockchips.h>
 #include <linux/cpu.h>
 #include <linux/sched/isolation.h>
@@ -2152,7 +2153,7 @@ void vmbus_device_unregister(struct hv_device *device_obj)
 	device_unregister(&device_obj->device);
 }
 
-
+#ifdef CONFIG_ACPI
 /*
  * VMBUS is an acpi enumerated device. Get the information we
  * need from DSDT.
@@ -2262,6 +2263,7 @@ static acpi_status vmbus_walk_resources(struct acpi_resource *res, void *ctx)
 
 	return AE_OK;
 }
+#endif
 
 static int vmbus_mmio_remove(void)
 {
@@ -2282,7 +2284,7 @@ static int vmbus_mmio_remove(void)
 	}
 }
 
-static void vmbus_reserve_fb(void)
+static void __maybe_unused vmbus_reserve_fb(void)
 {
 	resource_size_t start = 0, size;
 	struct pci_dev *pdev;
@@ -2442,6 +2444,7 @@ void vmbus_free_mmio(resource_size_t start, resource_size_t size)
 }
 EXPORT_SYMBOL_GPL(vmbus_free_mmio);
 
+#ifdef CONFIG_ACPI
 static int vmbus_acpi_add(struct platform_device *pdev)
 {
 	acpi_status result;
@@ -2494,10 +2497,52 @@ static int vmbus_acpi_add(struct platform_device *pdev)
 		vmbus_mmio_remove();
 	return ret_val;
 }
+#else
+
+static int vmbus_device_add(struct platform_device *pdev)
+{
+	struct resource **cur_res = &hyperv_mmio;
+	struct of_range range;
+	struct of_range_parser parser;
+	struct device_node *np;
+	int ret = 0;
+
+	hv_dev = &pdev->dev;
+	np = pdev->dev.of_node;
+
+	ret = of_range_parser_init(&parser, np);
+	if (ret) {
+		dev_err(hv_dev, "Failed to parse resources.\n");
+		return ret;
+	}
+
+	for_each_of_range(&parser, &range) {
+		struct resource *res;
+
+		res = kzalloc(sizeof(*res), GFP_ATOMIC);
+		if (!res)
+			return -ENOMEM;
+
+		res->name = "hyperv mmio";
+		res->flags = IORESOURCE_MEM | IORESOURCE_MEM_64;
+		res->start = range.pci_addr;
+		res->end = range.pci_addr + range.size;
+
+		*cur_res = res;
+		cur_res = &res->sibling;
+	}
+
+	return ret;
+}
+#endif
 
 static int vmbus_platform_driver_probe(struct platform_device *pdev)
 {
+#ifdef CONFIG_ACPI
 	return vmbus_acpi_add(pdev);
+#else
+	return vmbus_device_add(pdev);
+#endif
 }
 
 static int vmbus_platform_driver_remove(struct platform_device *pdev)
@@ -2643,6 +2688,16 @@ static int vmbus_bus_resume(struct device *dev)
 #define vmbus_bus_resume NULL
 #endif /* CONFIG_PM_SLEEP */
 
+static const struct of_device_id vmbus_of_match[] = {
+	{
+		.compatible = "microsoft,vmbus",
+	},
+	{
+		/* sentinel */
+	},
+};
+MODULE_DEVICE_TABLE(of, vmbus_of_match);
+
 static const struct acpi_device_id vmbus_acpi_device_ids[] = {
 	{"VMBUS", 0},
 	{"VMBus", 0},
@@ -2677,6 +2732,7 @@ static struct platform_driver vmbus_platform_driver = {
 	.driver = {
 		.name = "vmbus",
 		.acpi_match_table = ACPI_PTR(vmbus_acpi_device_ids),
+		.of_match_table = of_match_ptr(vmbus_of_match),
 		.pm = &vmbus_bus_pm,
 		.probe_type = PROBE_FORCE_SYNCHRONOUS,
 	}