virt: vmgenid: change implementation to use a platform driver

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>
Reviewed-by: Alexander Graf <graf@amazon.com>
Tested-by: Babis Chalios <bchalios@amazon.es>
[Jason: - Small style cleanups and refactoring.]
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

diff --git a/drivers/virt/vmgenid.c b/drivers/virt/vmgenid.c
index a1c467a0e9f719665fc02fa559d5c94545e5725f..0522107f9beebb24c14e790ebf6154f815405c40 100644 (file)
--- 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");
@@ -21,19 +22,41 @@ struct vmgenid_state {
        u8 this_id[VMGENID_SIZE];
 };
 
-static int vmgenid_add(struct acpi_device *device)
+static void vmgenid_notify(struct device *device)
+{
+       struct vmgenid_state *state = device->driver_data;
+       u8 old_id[VMGENID_SIZE];
+
+       memcpy(old_id, state->this_id, sizeof(old_id));
+       memcpy(state->this_id, state->next_id, sizeof(state->this_id));
+       if (!memcmp(old_id, state->this_id, sizeof(old_id)))
+               return;
+       add_vmfork_randomness(state->this_id, sizeof(state->this_id));
+}
+
+static void setup_vmgenid_state(struct vmgenid_state *state, void *virt_addr)
 {
+       state->next_id = virt_addr;
+       memcpy(state->this_id, state->next_id, sizeof(state->this_id));
+       add_device_randomness(state->this_id, sizeof(state->this_id));
+}
+
+static void vmgenid_acpi_handler(acpi_handle __always_unused handle,
+                                u32 __always_unused event, void *dev)
+{
+       vmgenid_notify(dev);
+}
+
+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;
+       void *virt_addr;
        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"));
@@ -49,53 +72,61 @@ 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 = devm_memremap(&device->dev, phys_addr, VMGENID_SIZE, MEMREMAP_WB);
+       if (IS_ERR(virt_addr)) {
+               ret = PTR_ERR(virt_addr);
                goto out;
        }
+       setup_vmgenid_state(state, virt_addr);
 
-       memcpy(state->this_id, state->next_id, sizeof(state->this_id));
-       add_device_randomness(state->this_id, sizeof(state->this_id));
-
-       device->driver_data = state;
+       status = acpi_install_notify_handler(device->handle, ACPI_DEVICE_NOTIFY,
+                                            vmgenid_acpi_handler, dev);
+       if (ACPI_FAILURE(status)) {
+               ret = -ENODEV;
+               goto out;
+       }
 
+       dev->driver_data = state;
 out:
        ACPI_FREE(parsed.pointer);
        return ret;
 }
 
-static void vmgenid_notify(struct acpi_device *device, u32 event)
+static int vmgenid_add(struct platform_device *pdev)
 {
-       struct vmgenid_state *state = acpi_driver_data(device);
-       u8 old_id[VMGENID_SIZE];
+       struct device *dev = &pdev->dev;
+       struct vmgenid_state *state;
+       int ret;
 
-       memcpy(old_id, state->this_id, sizeof(old_id));
-       memcpy(state->this_id, state->next_id, sizeof(state->this_id));
-       if (!memcmp(old_id, state->this_id, sizeof(old_id)))
-               return;
-       add_vmfork_randomness(state->this_id, sizeof(state->this_id));
+       state = devm_kmalloc(dev, sizeof(*state), GFP_KERNEL);
+       if (!state)
+               return -ENOMEM;
+
+       ret = vmgenid_add_acpi(dev, state);
+
+       if (ret < 0)
+               devm_kfree(dev, state);
+       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 },
        { }
 };
-
-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_DEVICE_TABLE(acpi, vmgenid_ids);
 MODULE_DESCRIPTION("Virtual Machine Generation ID");
 MODULE_LICENSE("GPL v2");
 MODULE_AUTHOR("Jason A. Donenfeld <Jason@zx2c4.com>");