[PATCH v6 2/5] virt: vmgenid: change implementation to use a platform driver

[Babis Chalios <bchalios@xxxxxxxxx>]

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

Co-authored-by: Sudan Landge <sudanl@xxxxxxxxxx>
Signed-off-by: Babis Chalios <bchalios@xxxxxxxxx>
Reviewed-by: Alexander Graf <graf@xxxxxxxxxx>
---
 drivers/virt/vmgenid.c | 97 +++++++++++++++++++++++++++++-------------
 1 file changed, 67 insertions(+), 30 deletions(-)

diff --git a/drivers/virt/vmgenid.c b/drivers/virt/vmgenid.c
index a167ccfad299..c028e2064fdd 100644
--- a/drivers/virt/vmgenid.c
+++ b/drivers/virt/vmgenid.c
@@ -7,9 +7,10 @@
  * information to random.c.
  */
 
+#include <linux/acpi.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
-#include <linux/acpi.h>
+#include <linux/platform_device.h>
 #include <linux/random.h>
 
 ACPI_MODULE_NAME("vmgenid");
@@ -21,9 +22,9 @@ 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];
 
@@ -32,21 +33,36 @@ 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 void vmgenid_acpi_handler(acpi_handle __always_unused handle,
+				 u32 __always_unused 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(struct acpi_device *device)
+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;
+	u8 *virt_addr;
 
 	status = acpi_evaluate_object(device->handle, "ADDR", NULL, &parsed);
 	if (ACPI_FAILURE(status)) {
@@ -63,40 +79,61 @@ 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);
+
+	virt_addr = (u8 *)devm_memremap(&device->dev, phys_addr,
+					VMGENID_SIZE, MEMREMAP_WB);
+	ret = setup_vmgenid_state(state, virt_addr);
+	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;
 }
 
-static const struct acpi_device_id vmgenid_ids[] = {
+static const struct acpi_device_id vmgenid_acpi_ids[] = {
 	{ "VMGENCTR", 0 },
 	{ "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
-	}
+MODULE_DEVICE_TABLE(acpi, vmgenid_acpi_ids);
+
+static struct platform_driver vmgenid_plaform_driver = {
+	.probe      = vmgenid_add,
+	.driver     = {
+		.name   = "vmgenid",
+		.acpi_match_table = vmgenid_acpi_ids,
+	},
 };
 
-module_acpi_driver(vmgenid_driver);
+module_platform_driver(vmgenid_plaform_driver)
 
 MODULE_DESCRIPTION("Virtual Machine Generation ID");
 MODULE_LICENSE("GPL v2");
-- 
2.40.1