[PATCH v2 2/4] virt: vmgenid: change implementation to use a platform driver

[Sudan Landge <sudanl@amazon.com>]

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