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, 73 insertions, 0 deletions

diff --git a/drivers/input/touchscreen/tsc2004.c b/drivers/input/touchscreen/tsc2004.c
new file mode 100644
index 000000000..130aeb735
--- /dev/null
+++ b/drivers/input/touchscreen/tsc2004.c
@@ -0,0 +1,73 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * TSC2004 touchscreen driver
+ *
+ * Copyright (C) 2015 QWERTY Embedded Design
+ * Copyright (C) 2015 EMAC Inc.
+ */
+
+#include <linux/module.h>
+#include <linux/input.h>
+#include <linux/of.h>
+#include <linux/i2c.h>
+#include <linux/regmap.h>
+#include "tsc200x-core.h"
+
+static const struct input_id tsc2004_input_id = {
+	.bustype = BUS_I2C,
+	.product = 2004,
+};
+
+static int tsc2004_cmd(struct device *dev, u8 cmd)
+{
+	u8 tx = TSC200X_CMD | TSC200X_CMD_12BIT | cmd;
+	s32 data;
+	struct i2c_client *i2c = to_i2c_client(dev);
+
+	data = i2c_smbus_write_byte(i2c, tx);
+	if (data < 0) {
+		dev_err(dev, "%s: failed, command: %x i2c error: %d\n",
+			__func__, cmd, data);
+		return data;
+	}
+
+	return 0;
+}
+
+static int tsc2004_probe(struct i2c_client *i2c)
+
+{
+	return tsc200x_probe(&i2c->dev, i2c->irq, &tsc2004_input_id,
+			     devm_regmap_init_i2c(i2c, &tsc200x_regmap_config),
+			     tsc2004_cmd);
+}
+
+static const struct i2c_device_id tsc2004_idtable[] = {
+	{ .name = "tsc2004" },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, tsc2004_idtable);
+
+#ifdef CONFIG_OF
+static const struct of_device_id tsc2004_of_match[] = {
+	{ .compatible = "ti,tsc2004" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, tsc2004_of_match);
+#endif
+
+static struct i2c_driver tsc2004_driver = {
+	.driver = {
+		.name		= "tsc2004",
+		.dev_groups	= tsc200x_groups,
+		.of_match_table	= of_match_ptr(tsc2004_of_match),
+		.pm		= pm_sleep_ptr(&tsc200x_pm_ops),
+	},
+	.id_table       = tsc2004_idtable,
+	.probe          = tsc2004_probe,
+};
+module_i2c_driver(tsc2004_driver);
+
+MODULE_AUTHOR("Michael Welling <mwelling@ieee.org>");
+MODULE_DESCRIPTION("TSC2004 Touchscreen Driver");
+MODULE_LICENSE("GPL");