Re-implement vmgenid as a platform driver in preparation
for adding devicetree bindings support in next commits.

Signed-off-by: Sudan Landge <sudanl@amazon.com>
---
 drivers/virt/vmgenid.c | 101 ++++++++++++++++++++++++++++++-----------
 1 file changed, 74 insertions(+), 27 deletions(-)

diff --git a/drivers/virt/vmgenid.c b/drivers/virt/vmgenid.c
index ea956df02874..d5394c706bd9 100644
--- a/drivers/virt/vmgenid.c
+++ b/drivers/virt/vmgenid.c
@@ -11,6 +11,8 @@
 #include <linux/module.h>
 #include <linux/acpi.h>
 #include <linux/random.h>
+#include <acpi/actypes.h>
+#include <linux/platform_device.h>
 
 ACPI_MODULE_NAME("vmgenid");
 
@@ -21,9 +23,9 @@ struct vmgenid_state {
 	u8 this_id[VMGENID_SIZE];
 };
 
-static void vmgenid_notify(struct acpi_device *device, u32 event)
+static void vmgenid_notify(struct device *device)
 {
-	struct vmgenid_state *state = acpi_driver_data(device);
+	struct vmgenid_state *state = device->driver_data;
 	char *envp[] = { "NEW_VMGENID=1", NULL };
 	u8 old_id[VMGENID_SIZE];
 
@@ -32,22 +34,34 @@ static void vmgenid_notify(struct acpi_device *device, u32 event)
 	if (!memcmp(old_id, state->this_id, sizeof(old_id)))
 		return;
 	add_vmfork_randomness(state->this_id, sizeof(state->this_id));
-	kobject_uevent_env(&device->dev.kobj, KOBJ_CHANGE, envp);
+	kobject_uevent_env(&device->kobj, KOBJ_CHANGE, envp);
 }
 
-static int vmgenid_add(struct acpi_device *device)
+static void vmgenid_acpi_handler(acpi_handle handle, u32 event, void *dev)
 {
+	vmgenid_notify(dev);
+}
+
+static int setup_vmgenid_state(struct vmgenid_state *state, u8 *next_id)
+{
+	if (IS_ERR(next_id))
+		return PTR_ERR(next_id);
+
+	state->next_id = next_id;
+	memcpy(state->this_id, state->next_id, sizeof(state->this_id));
+	add_device_randomness(state->this_id, sizeof(state->this_id));
+	return 0;
+}
+
+static int vmgenid_add_acpi(struct device *dev, struct vmgenid_state *state)
+{
+	struct acpi_device *device = ACPI_COMPANION(dev);
 	struct acpi_buffer parsed = { ACPI_ALLOCATE_BUFFER };
-	struct vmgenid_state *state;
 	union acpi_object *obj;
 	phys_addr_t phys_addr;
 	acpi_status status;
 	int ret = 0;
 
-	state = devm_kmalloc(&device->dev, sizeof(*state), GFP_KERNEL);
-	if (!state)
-		return -ENOMEM;
-
 	status = acpi_evaluate_object(device->handle, "ADDR", NULL, &parsed);
 	if (ACPI_FAILURE(status)) {
 		ACPI_EXCEPTION((AE_INFO, status, "Evaluating ADDR"));
@@ -63,19 +77,42 @@ static int vmgenid_add(struct acpi_device *device)
 
 	phys_addr = (obj->package.elements[0].integer.value << 0) |
 		    (obj->package.elements[1].integer.value << 32);
-	state->next_id = devm_memremap(&device->dev, phys_addr, VMGENID_SIZE, MEMREMAP_WB);
-	if (IS_ERR(state->next_id)) {
-		ret = PTR_ERR(state->next_id);
+
+	ret = setup_vmgenid_state(state,
+				  (u8 *)devm_memremap(&device->dev, phys_addr,
+						      VMGENID_SIZE, MEMREMAP_WB));
+	if (ret)
+		goto out;
+
+	dev->driver_data = state;
+	status = acpi_install_notify_handler(device->handle, ACPI_DEVICE_NOTIFY,
+					     vmgenid_acpi_handler, dev);
+	if (ACPI_FAILURE(status)) {
+		dev_err(dev, "Failed to install acpi notify handler");
+		ret = -ENODEV;
+		dev->driver_data = NULL;
 		goto out;
 	}
+out:
+	ACPI_FREE(parsed.pointer);
+	return ret;
+}
 
-	memcpy(state->this_id, state->next_id, sizeof(state->this_id));
-	add_device_randomness(state->this_id, sizeof(state->this_id));
+static int vmgenid_add(struct platform_device *pdev)
+{
+	struct vmgenid_state *state;
+	struct device *dev = &pdev->dev;
+	int ret = 0;
 
-	device->driver_data = state;
+	state = devm_kmalloc(dev, sizeof(*state), GFP_KERNEL);
+	if (!state)
+		return -ENOMEM;
+
+	ret = vmgenid_add_acpi(dev, state);
+
+	if (ret)
+		devm_kfree(dev, state);
 
-out:
-	ACPI_FREE(parsed.pointer);
 	return ret;
 }
 
@@ -84,20 +121,30 @@ static const struct acpi_device_id vmgenid_ids[] = {
 	{ "VM_GEN_COUNTER", 0 },
 	{ }
 };
+MODULE_DEVICE_TABLE(acpi, vmgenid_ids);
 
-static struct acpi_driver vmgenid_driver = {
-	.name = "vmgenid",
-	.ids = vmgenid_ids,
-	.owner = THIS_MODULE,
-	.ops = {
-		.add = vmgenid_add,
-		.notify = vmgenid_notify
-	}
+static struct platform_driver vmgenid_plaform_driver = {
+	.probe      = vmgenid_add,
+	.driver     = {
+		.name   = "vmgenid",
+		.acpi_match_table = ACPI_PTR(vmgenid_ids),
+		.owner = THIS_MODULE,
+	},
 };
 
-module_acpi_driver(vmgenid_driver);
+static int vmgenid_platform_device_init(void)
+{
+	return platform_driver_register(&vmgenid_plaform_driver);
+}
+
+static void vmgenid_platform_device_exit(void)
+{
+	platform_driver_unregister(&vmgenid_plaform_driver);
+}
+
+module_init(vmgenid_platform_device_init)
+module_exit(vmgenid_platform_device_exit)
 
-MODULE_DEVICE_TABLE(acpi, vmgenid_ids);
 MODULE_DESCRIPTION("Virtual Machine Generation ID");
 MODULE_LICENSE("GPL v2");
 MODULE_AUTHOR("Jason A. Donenfeld <Jason@zx2c4.com>");
-- 
2.40.1

On 25/03/2024 20:53, Sudan Landge wrote:
> Re-implement vmgenid as a platform driver in preparation
> for adding devicetree bindings support in next commits.
> 
> Signed-off-by: Sudan Landge <sudanl@amazon.com>
> ---
>  drivers/virt/vmgenid.c | 101 ++++++++++++++++++++++++++++++-----------
>  1 file changed, 74 insertions(+), 27 deletions(-)
> 
> diff --git a/drivers/virt/vmgenid.c b/drivers/virt/vmgenid.c
> index ea956df02874..d5394c706bd9 100644
> --- a/drivers/virt/vmgenid.c
> +++ b/drivers/virt/vmgenid.c
> @@ -11,6 +11,8 @@
>  #include <linux/module.h>
>  #include <linux/acpi.h>
>  #include <linux/random.h>
> +#include <acpi/actypes.h>
> +#include <linux/platform_device.h>

Do not add headers to the end of lists.

>  
>  ACPI_MODULE_NAME("vmgenid");
>  

...

>  
> -static struct acpi_driver vmgenid_driver = {
> -	.name = "vmgenid",
> -	.ids = vmgenid_ids,
> -	.owner = THIS_MODULE,
> -	.ops = {
> -		.add = vmgenid_add,
> -		.notify = vmgenid_notify
> -	}
> +static struct platform_driver vmgenid_plaform_driver = {
> +	.probe      = vmgenid_add,
> +	.driver     = {
> +		.name   = "vmgenid",
> +		.acpi_match_table = ACPI_PTR(vmgenid_ids),

ACPI_PTR does not make sense. If this can be compile tested !ACPI, then
this is wrong. If this cannot be compile tested, then this is redundant
and confusing so... also wrong.

> +		.owner = THIS_MODULE,
> +	},
>  };
>  
> -module_acpi_driver(vmgenid_driver);
> +static int vmgenid_platform_device_init(void)
> +{
> +	return platform_driver_register(&vmgenid_plaform_driver);
> +}
> +
> +static void vmgenid_platform_device_exit(void)
> +{
> +	platform_driver_unregister(&vmgenid_plaform_driver);
> +}
> +
> +module_init(vmgenid_platform_device_init)
> +module_exit(vmgenid_platform_device_exit)

Why this cannot be module_platform_driver?



Best regards,
Krzysztof