ptp: ptp_vmclock: Add device tree support

Add device tree support to the ptp_vmclock driver, allowing it to probe
via device tree in addition to ACPI.

Handle optional interrupt for clock disruption notifications, mirroring
the ACPI notification behaviour.

Although the interrupt is marked as 'optional' in the DT bindings, if
the device *advertises* the VMCLOCK_FLAG_NOTIFICATION_ABSENT then it
*should* have an interrupt. The driver will refuse to initialize if not.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Babis Chalios <bchalios@amazon.es>
Signed-off-by: Takahiro Itazuri <itazur@amazon.com>
Tested-by: Takahiro Itazuri <itazur@amazon.com>
Link: https://patch.msgid.link/20260130173704.12575-5-itazur@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 61 insertions, 6 deletions

diff --git a/drivers/ptp/ptp_vmclock.c b/drivers/ptp/ptp_vmclock.c
index f8b24f9e85cd..619c8e5a9998 100644
--- a/drivers/ptp/ptp_vmclock.c
+++ b/drivers/ptp/ptp_vmclock.c
@@ -14,10 +14,13 @@
 #include <linux/file.h>
 #include <linux/fs.h>
 #include <linux/init.h>
+#include <linux/io.h>
+#include <linux/interrupt.h>
 #include <linux/kernel.h>
 #include <linux/miscdevice.h>
 #include <linux/mm.h>
 #include <linux/module.h>
+#include <linux/of.h>
 #include <linux/platform_device.h>
 #include <linux/slab.h>
 
@@ -524,7 +527,7 @@ vmclock_acpi_notification_handler(acpi_handle __always_unused handle,
 	wake_up_interruptible(&st->disrupt_wait);
 }
 
-static int vmclock_setup_notification(struct device *dev, struct vmclock_state *st)
+static int vmclock_setup_acpi_notification(struct device *dev)
 {
 	struct acpi_device *adev = ACPI_COMPANION(dev);
 	acpi_status status;
@@ -537,10 +540,6 @@ static int vmclock_setup_notification(struct device *dev, struct vmclock_state *
 	if (!adev)
 		return -ENODEV;
 
-	/* The device does not support notifications. Nothing else to do */
-	if (!(le64_to_cpu(st->clk->flags) & VMCLOCK_FLAG_NOTIFICATION_PRESENT))
-		return 0;
-
 	status = acpi_install_notify_handler(adev->handle, ACPI_DEVICE_NOTIFY,
 					     vmclock_acpi_notification_handler,
 					     dev);
@@ -575,6 +574,55 @@ static int vmclock_probe_acpi(struct device *dev, struct vmclock_state *st)
 	return 0;
 }
 
+static irqreturn_t vmclock_of_irq_handler(int __always_unused irq, void *_st)
+{
+	struct vmclock_state *st = _st;
+
+	wake_up_interruptible(&st->disrupt_wait);
+	return IRQ_HANDLED;
+}
+
+static int vmclock_probe_dt(struct device *dev, struct vmclock_state *st)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct resource *res;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res)
+		return -ENODEV;
+
+	st->res = *res;
+
+	return 0;
+}
+
+static int vmclock_setup_of_notification(struct device *dev)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	int irq;
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0)
+		return irq;
+
+	return devm_request_irq(dev, irq, vmclock_of_irq_handler, IRQF_SHARED,
+				"vmclock", dev->driver_data);
+}
+
+static int vmclock_setup_notification(struct device *dev,
+				      struct vmclock_state *st)
+{
+	/* The device does not support notifications. Nothing else to do */
+	if (!(le64_to_cpu(st->clk->flags) & VMCLOCK_FLAG_NOTIFICATION_PRESENT))
+		return 0;
+
+	if (has_acpi_companion(dev)) {
+		return vmclock_setup_acpi_notification(dev);
+	} else {
+		return vmclock_setup_of_notification(dev);
+	}
+}
+
 static void vmclock_remove(void *data)
 {
 	struct device *dev = data;
@@ -619,7 +667,7 @@ static int vmclock_probe(struct platform_device *pdev)
 	if (has_acpi_companion(dev))
 		ret = vmclock_probe_acpi(dev, st);
 	else
-		ret = -EINVAL; /* Only ACPI for now */
+		ret = vmclock_probe_dt(dev, st);
 
 	if (ret) {
 		dev_info(dev, "Failed to obtain physical address: %d\n", ret);
@@ -719,11 +767,18 @@ static const struct acpi_device_id vmclock_acpi_ids[] = {
 };
 MODULE_DEVICE_TABLE(acpi, vmclock_acpi_ids);
 
+static const struct of_device_id vmclock_of_ids[] = {
+	{ .compatible = "amazon,vmclock", },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, vmclock_of_ids);
+
 static struct platform_driver vmclock_platform_driver = {
 	.probe		= vmclock_probe,
 	.driver	= {
 		.name	= "vmclock",
 		.acpi_match_table = vmclock_acpi_ids,
+		.of_match_table = vmclock_of_ids,
 	},
 };