ACPI: APEI: EINJ: Transition to the faux device interface

The APEI error injection driver does not require the creation of a
platform device. Originally, this approach was chosen for simplicity
when the driver was first implemented.

With the introduction of the lightweight faux device interface, we now
have a more appropriate alternative. Migrate the driver to utilize the
faux bus, given that the platform device it previously created was not
a real one anyway. This will simplify the code, reducing its footprint
while maintaining functionality.

Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Link: https://patch.msgid.link/20250317-plat2faux_dev-v1-8-5fe67c085ad5@arm.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/drivers/acpi/apei/einj-core.c b/drivers/acpi/apei/einj-core.c
index 04731a5b01faaba534bad853d0acc4c8a873a53b..7ff334422899e757de918107202507dd171d61da 100644 (file)
--- a/drivers/acpi/apei/einj-core.c
+++ b/drivers/acpi/apei/einj-core.c
@@ -21,7 +21,7 @@
 #include <linux/nmi.h>
 #include <linux/delay.h>
 #include <linux/mm.h>
-#include <linux/platform_device.h>
+#include <linux/device/faux.h>
 #include <linux/unaligned.h>
 
 #include "apei-internal.h"
@@ -749,7 +749,7 @@ static int einj_check_table(struct acpi_table_einj *einj_tab)
        return 0;
 }
 
-static int __init einj_probe(struct platform_device *pdev)
+static int __init einj_probe(struct faux_device *fdev)
 {
        int rc;
        acpi_status status;
@@ -851,7 +851,7 @@ err_put_table:
        return rc;
 }
 
-static void __exit einj_remove(struct platform_device *pdev)
+static void __exit einj_remove(struct faux_device *fdev)
 {
        struct apei_exec_context ctx;
 
@@ -872,34 +872,25 @@ static void __exit einj_remove(struct platform_device *pdev)
        acpi_put_table((struct acpi_table_header *)einj_tab);
 }
 
-static struct platform_device *einj_dev;
+static struct faux_device *einj_dev;
 /*
  * einj_remove() lives in .exit.text. For drivers registered via
  * platform_driver_probe() this is ok because they cannot get unbound at
  * runtime. So mark the driver struct with __refdata to prevent modpost
  * triggering a section mismatch warning.
  */
-static struct platform_driver einj_driver __refdata = {
+static struct faux_device_ops einj_device_ops __refdata = {
+       .probe = einj_probe,
        .remove = __exit_p(einj_remove),
-       .driver = {
-               .name = "acpi-einj",
-       },
 };
 
 static int __init einj_init(void)
 {
-       struct platform_device_info einj_dev_info = {
-               .name = "acpi-einj",
-               .id = -1,
-       };
-       int rc;
-
-       einj_dev = platform_device_register_full(&einj_dev_info);
-       if (IS_ERR(einj_dev))
-               return PTR_ERR(einj_dev);
+       einj_dev = faux_device_create("acpi-einj", NULL, &einj_device_ops);
+       if (!einj_dev)
+               return -ENODEV;
 
-       rc = platform_driver_probe(&einj_driver, einj_probe);
-       einj_initialized = rc == 0;
+       einj_initialized = true;
 
        return 0;
 }
@@ -907,9 +898,8 @@ static int __init einj_init(void)
 static void __exit einj_exit(void)
 {
        if (einj_initialized)
-               platform_driver_unregister(&einj_driver);
+               faux_device_destroy(einj_dev);
 
-       platform_device_unregister(einj_dev);
 }
 
 module_init(einj_init);