[PATCH v4 4/9] x86/microcode: move away from using a fake platform device

Greg Kroah-Hartman
2025-02-10T12:30:53Z

Downloading firmware needs a device to hang off of, and so a platform
device seemed like the simplest way to do this. Now that we have a faux
device interface, use that instead as this "microcode device" is not
anything resembling a platform device at all.

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
v4: - api tweaked due to parent pointer added to faux_device create
function.
v3: no change
v2: new example patch in this series
arch/x86/kernel/cpu/microcode/core.c | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c
index b3658d11e7b6..35de3db8bc60 100644
--- a/arch/x86/kernel/cpu/microcode/core.c
+++ b/arch/x86/kernel/cpu/microcode/core.c
@@ -17,8 +17,8 @@

#define pr_fmt(fmt) "microcode: " fmt

-#include <linux/platform_device.h>
#include <linux/stop_machine.h>
+#include <linux/device/faux.h>
#include <linux/syscore_ops.h>
#include <linux/miscdevice.h>
#include <linux/capability.h>
@@ -238,7 +238,7 @@ static void reload_early_microcode(unsigned int cpu)
}

/* fake device for request_firmware */
-static struct platform_device *microcode_pdev;
+static struct faux_device *microcode_fdev;

#ifdef CONFIG_MICROCODE_LATE_LOADING
/*
@@ -679,7 +679,7 @@ static int load_late_locked(void)
if (!setup_cpus())
return -EBUSY;

- switch (microcode_ops->request_microcode_fw(0, &microcode_pdev->dev)) {
+ switch (microcode_ops->request_microcode_fw(0, &microcode_fdev->dev)) {
case UCODE_NEW:
return load_late_stop_cpus(false);
case UCODE_NEW_SAFE:
@@ -828,9 +828,9 @@ static int __init microcode_init(void)
if (early_data.new_rev)
pr_info_once("Updated early from: 0x%08x\n", early_data.old_rev);

- microcode_pdev = platform_device_register_simple("microcode", -1, NULL, 0);
- if (IS_ERR(microcode_pdev))
- return PTR_ERR(microcode_pdev);
+ microcode_fdev = faux_device_create("microcode", NULL, NULL);
+ if (!microcode_fdev)
+ return -ENODEV;

dev_root = bus_get_dev_root(&cpu_subsys);
if (dev_root) {
@@ -849,7 +849,7 @@ static int __init microcode_init(void)
return 0;

out_pdev:
- platform_device_unregister(microcode_pdev);
+ faux_device_destroy(microcode_fdev);
return error;

}
--
2.48.1