x86/amd_node: Fix PCI device reference counting in amd_smn_init()grafted

The local "root" pointer is a temporary variable used during the device
search. Therefore, refcount related to the search iterators should be cleaned
up after the search is complete.

Use the __free() cleanup macro to ensure the refcount is decremented when the
temporary pointer goes out of scope.

Additionally, increment the refcount when caching a root pointer. This ensures
the in-use refcount is separate from the temporary search refcounting.

Finally, drop the redundant "root = NULL" before the second search loop. The
pci_get_class() iterator always decrements the refcount of its "from"
argument, so the first loop can only fall through with "root" already NULL.

Fixes: 0a4b61d9c2e4 ("x86/amd_node: Fix AMD root device caching")
Closes: https://sashiko.dev/#/patchset/20260806160159.230453-1-jason.andryuk%40amd.com
Reported-by: Sashiko <sashiko-bot@kernel.org>
Assisted-by: LLM
Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>
Cc: <stable@kernel.org>
Link: https://patch.msgid.link/20260903154325.74343-1-yazen.ghannam@amd.com

1 files changed, 98 insertions, 0 deletions

diff --git a/drivers/input/misc/88pm886-onkey.c b/drivers/input/misc/88pm886-onkey.c
new file mode 100644
index 000000000..284ff5190
--- /dev/null
+++ b/drivers/input/misc/88pm886-onkey.c
@@ -0,0 +1,98 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/input.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+
+#include <linux/mfd/88pm886.h>
+
+struct pm886_onkey {
+	struct input_dev *idev;
+	struct pm886_chip *chip;
+};
+
+static irqreturn_t pm886_onkey_irq_handler(int irq, void *data)
+{
+	struct pm886_onkey *onkey = data;
+	struct regmap *regmap = onkey->chip->regmap;
+	struct input_dev *idev = onkey->idev;
+	struct device *parent = idev->dev.parent;
+	unsigned int val;
+	int err;
+
+	err = regmap_read(regmap, PM886_REG_STATUS1, &val);
+	if (err) {
+		dev_err(parent, "Failed to read status: %d\n", err);
+		return IRQ_NONE;
+	}
+	val &= PM886_ONKEY_STS1;
+
+	input_report_key(idev, KEY_POWER, val);
+	input_sync(idev);
+
+	return IRQ_HANDLED;
+}
+
+static int pm886_onkey_probe(struct platform_device *pdev)
+{
+	struct pm886_chip *chip = dev_get_drvdata(pdev->dev.parent);
+	struct device *dev = &pdev->dev;
+	struct pm886_onkey *onkey;
+	struct input_dev *idev;
+	int irq, err;
+
+	onkey = devm_kzalloc(dev, sizeof(*onkey), GFP_KERNEL);
+	if (!onkey)
+		return -ENOMEM;
+
+	onkey->chip = chip;
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0)
+		return dev_err_probe(dev, irq, "Failed to get IRQ\n");
+
+	idev = devm_input_allocate_device(dev);
+	if (!idev) {
+		dev_err(dev, "Failed to allocate input device\n");
+		return -ENOMEM;
+	}
+	onkey->idev = idev;
+
+	idev->name = "88pm886-onkey";
+	idev->phys = "88pm886-onkey/input0";
+	idev->id.bustype = BUS_I2C;
+
+	input_set_capability(idev, EV_KEY, KEY_POWER);
+
+	err = devm_request_threaded_irq(dev, irq, NULL, pm886_onkey_irq_handler,
+					IRQF_ONESHOT | IRQF_NO_SUSPEND, "onkey",
+					onkey);
+	if (err)
+		return dev_err_probe(dev, err, "Failed to request IRQ\n");
+
+	err = input_register_device(idev);
+	if (err)
+		return dev_err_probe(dev, err, "Failed to register input device\n");
+
+	return 0;
+}
+
+static const struct platform_device_id pm886_onkey_id_table[] = {
+	{ "88pm886-onkey", },
+	{ }
+};
+MODULE_DEVICE_TABLE(platform, pm886_onkey_id_table);
+
+static struct platform_driver pm886_onkey_driver = {
+	.driver = {
+		.name = "88pm886-onkey",
+	},
+	.probe = pm886_onkey_probe,
+	.id_table = pm886_onkey_id_table,
+};
+module_platform_driver(pm886_onkey_driver);
+
+MODULE_DESCRIPTION("Marvell 88PM886 onkey driver");
+MODULE_AUTHOR("Karel Balej <balejk@matfyz.cz>");
+MODULE_LICENSE("GPL");