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, 115 insertions, 0 deletions

diff --git a/drivers/regulator/88pg86x.c b/drivers/regulator/88pg86x.c
new file mode 100644
index 000000000..8c25a1db4
--- /dev/null
+++ b/drivers/regulator/88pg86x.c
@@ -0,0 +1,115 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/of.h>
+#include <linux/regulator/driver.h>
+#include <linux/regmap.h>
+
+static const struct regulator_ops pg86x_ops = {
+	.set_voltage_sel = regulator_set_voltage_sel_regmap,
+	.get_voltage_sel = regulator_get_voltage_sel_regmap,
+	.list_voltage = regulator_list_voltage_linear_range,
+};
+
+static const struct linear_range pg86x_buck1_ranges[] = {
+	REGULATOR_LINEAR_RANGE(      0,  0, 10,     0),
+	REGULATOR_LINEAR_RANGE(1000000, 11, 34, 25000),
+	REGULATOR_LINEAR_RANGE(1600000, 35, 47, 50000),
+};
+
+static const struct linear_range pg86x_buck2_ranges[] = {
+	REGULATOR_LINEAR_RANGE(      0,  0, 15,     0),
+	REGULATOR_LINEAR_RANGE(1000000, 16, 39, 25000),
+	REGULATOR_LINEAR_RANGE(1600000, 40, 52, 50000),
+};
+
+static const struct regulator_desc pg86x_regulators[] = {
+	{
+		.id = 0,
+		.type = REGULATOR_VOLTAGE,
+		.name = "buck1",
+		.of_match = of_match_ptr("buck1"),
+		.n_voltages = 11 + 24 + 13,
+		.linear_ranges = pg86x_buck1_ranges,
+		.n_linear_ranges = 3,
+		.vsel_reg  = 0x24,
+		.vsel_mask = 0xff,
+		.ops = &pg86x_ops,
+		.owner = THIS_MODULE
+	},
+	{
+		.id = 1,
+		.type = REGULATOR_VOLTAGE,
+		.name = "buck2",
+		.of_match = of_match_ptr("buck2"),
+		.n_voltages = 16 + 24 + 13,
+		.linear_ranges = pg86x_buck2_ranges,
+		.n_linear_ranges = 3,
+		.vsel_reg  = 0x13,
+		.vsel_mask = 0xff,
+		.ops = &pg86x_ops,
+		.owner = THIS_MODULE
+	},
+};
+
+static const struct regmap_config pg86x_regmap = {
+	.reg_bits = 8,
+	.val_bits = 8,
+};
+
+static int pg86x_i2c_probe(struct i2c_client *i2c)
+{
+	int id, ret;
+	struct regulator_config config = {.dev = &i2c->dev};
+	struct regmap *regmap = devm_regmap_init_i2c(i2c, &pg86x_regmap);
+
+	if (IS_ERR(regmap)) {
+		ret = PTR_ERR(regmap);
+		dev_err(&i2c->dev, "regmap init failed: %d\n", ret);
+		return ret;
+	}
+
+	for (id = 0; id < ARRAY_SIZE(pg86x_regulators); id++) {
+		struct regulator_dev *rdev;
+		rdev = devm_regulator_register(&i2c->dev,
+					       &pg86x_regulators[id],
+					       &config);
+		if (IS_ERR(rdev)) {
+			ret = PTR_ERR(rdev);
+			dev_err(&i2c->dev, "failed to register %s: %d\n",
+				pg86x_regulators[id].name, ret);
+			return ret;
+		}
+	}
+	return 0;
+}
+
+static const struct of_device_id __maybe_unused pg86x_dt_ids[] = {
+	{ .compatible = "marvell,88pg867" },
+	{ .compatible = "marvell,88pg868" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, pg86x_dt_ids);
+
+static const struct i2c_device_id pg86x_i2c_id[] = {
+	{ .name = "88pg867" },
+	{ .name = "88pg868" },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, pg86x_i2c_id);
+
+static struct i2c_driver pg86x_regulator_driver = {
+	.driver = {
+		.name = "88pg86x",
+		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
+		.of_match_table = of_match_ptr(pg86x_dt_ids),
+	},
+	.probe = pg86x_i2c_probe,
+	.id_table = pg86x_i2c_id,
+};
+
+module_i2c_driver(pg86x_regulator_driver);
+
+MODULE_DESCRIPTION("Marvell 88PG86X voltage regulator");
+MODULE_AUTHOR("Alexander Monakov <amonakov@gmail.com>");
+MODULE_LICENSE("GPL");