[PATCH v1] platform/x86: thinkpad_acpi: Drop ACPI driver registration

[Rafael J. Wysocki]

From: "Rafael J. Wysocki" <rafael.j.wysocki@xxxxxxxxx>

There is no point in registering an ACPI driver that only has an empty
.add() callback, which is done by the thinkpad_acpi driver, since
after binding to an ACPI device it only sits there and does nothing.

That binding only effectively causes the ACPI device's reference count
to increase, but that can be achieved by using acpi_get_acpi_dev()
instead of acpi_fetch_acpi_dev() in setup_acpi_notify(), and doing
the corresponding cleanup in ibm_exit().

Update the code accordingly and get rid of the non-functional ACPI
driver.

No intentional functional impact beyond altering sysfs content.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
---
 drivers/platform/x86/lenovo/thinkpad_acpi.c | 62 ++-------------------
 1 file changed, 4 insertions(+), 58 deletions(-)

diff --git a/drivers/platform/x86/lenovo/thinkpad_acpi.c b/drivers/platform/x86/lenovo/thinkpad_acpi.c
index 8982d92dfd97..9e1614754cd7 100644
--- a/drivers/platform/x86/lenovo/thinkpad_acpi.c
+++ b/drivers/platform/x86/lenovo/thinkpad_acpi.c
@@ -299,7 +299,6 @@ struct ibm_struct;
 
 struct tp_acpi_drv_struct {
 	const struct acpi_device_id *hid;
-	struct acpi_driver *driver;
 
 	void (*notify) (struct ibm_struct *, u32);
 	acpi_handle *handle;
@@ -322,7 +321,6 @@ struct ibm_struct {
 	struct tp_acpi_drv_struct *acpi;
 
 	struct {
-		u8 acpi_driver_registered:1;
 		u8 acpi_notify_installed:1;
 		u8 proc_created:1;
 		u8 init_called:1;
@@ -832,9 +830,9 @@ static int __init setup_acpi_notify(struct ibm_struct *ibm)
 	vdbg_printk(TPACPI_DBG_INIT,
 		"setting up ACPI notify for %s\n", ibm->name);
 
-	ibm->acpi->device = acpi_fetch_acpi_dev(*ibm->acpi->handle);
+	ibm->acpi->device = acpi_get_acpi_dev(*ibm->acpi->handle);
 	if (!ibm->acpi->device) {
-		pr_err("acpi_fetch_acpi_dev(%s) failed\n", ibm->name);
+		pr_err("acpi_get_acpi_dev(%s) failed\n", ibm->name);
 		return -ENODEV;
 	}
 
@@ -859,44 +857,6 @@ static int __init setup_acpi_notify(struct ibm_struct *ibm)
 	return 0;
 }
 
-static int __init tpacpi_device_add(struct acpi_device *device)
-{
-	return 0;
-}
-
-static int __init register_tpacpi_subdriver(struct ibm_struct *ibm)
-{
-	int rc;
-
-	dbg_printk(TPACPI_DBG_INIT,
-		"registering %s as an ACPI driver\n", ibm->name);
-
-	BUG_ON(!ibm->acpi);
-
-	ibm->acpi->driver = kzalloc_obj(struct acpi_driver);
-	if (!ibm->acpi->driver) {
-		pr_err("failed to allocate memory for ibm->acpi->driver\n");
-		return -ENOMEM;
-	}
-
-	sprintf(ibm->acpi->driver->name, "%s_%s", TPACPI_NAME, ibm->name);
-	ibm->acpi->driver->ids = ibm->acpi->hid;
-
-	ibm->acpi->driver->ops.add = &tpacpi_device_add;
-
-	rc = acpi_bus_register_driver(ibm->acpi->driver);
-	if (rc < 0) {
-		pr_err("acpi_bus_register_driver(%s) failed: %d\n",
-		       ibm->name, rc);
-		kfree(ibm->acpi->driver);
-		ibm->acpi->driver = NULL;
-	} else if (!rc)
-		ibm->flags.acpi_driver_registered = 1;
-
-	return rc;
-}
-
-
 /****************************************************************************
  ****************************************************************************
  *
@@ -11532,6 +11492,8 @@ static void ibm_exit(struct ibm_struct *ibm)
 		acpi_remove_notify_handler(*ibm->acpi->handle,
 					   ibm->acpi->type,
 					   dispatch_acpi_notify);
+		ibm->acpi->device->driver_data = NULL;
+		acpi_dev_put(ibm->acpi->device);
 		ibm->flags.acpi_notify_installed = 0;
 	}
 
@@ -11542,16 +11504,6 @@ static void ibm_exit(struct ibm_struct *ibm)
 		ibm->flags.proc_created = 0;
 	}
 
-	if (ibm->flags.acpi_driver_registered) {
-		dbg_printk(TPACPI_DBG_EXIT,
-			"%s: acpi_bus_unregister_driver\n", ibm->name);
-		BUG_ON(!ibm->acpi);
-		acpi_bus_unregister_driver(ibm->acpi->driver);
-		kfree(ibm->acpi->driver);
-		ibm->acpi->driver = NULL;
-		ibm->flags.acpi_driver_registered = 0;
-	}
-
 	if (ibm->flags.init_called && ibm->exit) {
 		ibm->exit();
 		ibm->flags.init_called = 0;
@@ -11587,12 +11539,6 @@ static int __init ibm_init(struct ibm_init_struct *iibm)
 	}
 
 	if (ibm->acpi) {
-		if (ibm->acpi->hid) {
-			ret = register_tpacpi_subdriver(ibm);
-			if (ret)
-				goto err_out;
-		}
-
 		if (ibm->acpi->notify) {
 			ret = setup_acpi_notify(ibm);
 			if (ret == -ENODEV) {
-- 
2.51.0