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, 161 insertions, 0 deletions

diff --git a/drivers/reset/reset-qcom-pdc.c b/drivers/reset/reset-qcom-pdc.c
new file mode 100644
index 000000000..ae2b5aba7
--- /dev/null
+++ b/drivers/reset/reset-qcom-pdc.c
@@ -0,0 +1,161 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2018 The Linux Foundation. All rights reserved.
+ */
+
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/reset-controller.h>
+
+#include <dt-bindings/reset/qcom,sdm845-pdc.h>
+
+#define RPMH_SDM845_PDC_SYNC_RESET	0x100
+#define RPMH_SC7280_PDC_SYNC_RESET	0x1000
+
+struct qcom_pdc_reset_map {
+	u8 bit;
+};
+
+struct qcom_pdc_reset_desc {
+	const struct qcom_pdc_reset_map *resets;
+	size_t num_resets;
+	unsigned int offset;
+};
+
+struct qcom_pdc_reset_data {
+	struct reset_controller_dev rcdev;
+	struct regmap *regmap;
+	const struct qcom_pdc_reset_desc *desc;
+};
+
+static const struct regmap_config pdc_regmap_config = {
+	.name		= "pdc-reset",
+	.reg_bits	= 32,
+	.reg_stride	= 4,
+	.val_bits	= 32,
+	.max_register	= 0x20000,
+};
+
+static const struct qcom_pdc_reset_map sdm845_pdc_resets[] = {
+	[PDC_APPS_SYNC_RESET] = {0},
+	[PDC_SP_SYNC_RESET] = {1},
+	[PDC_AUDIO_SYNC_RESET] = {2},
+	[PDC_SENSORS_SYNC_RESET] = {3},
+	[PDC_AOP_SYNC_RESET] = {4},
+	[PDC_DEBUG_SYNC_RESET] = {5},
+	[PDC_GPU_SYNC_RESET] = {6},
+	[PDC_DISPLAY_SYNC_RESET] = {7},
+	[PDC_COMPUTE_SYNC_RESET] = {8},
+	[PDC_MODEM_SYNC_RESET] = {9},
+};
+
+static const struct qcom_pdc_reset_desc sdm845_pdc_reset_desc = {
+	.resets = sdm845_pdc_resets,
+	.num_resets = ARRAY_SIZE(sdm845_pdc_resets),
+	.offset = RPMH_SDM845_PDC_SYNC_RESET,
+};
+
+static const struct qcom_pdc_reset_map sc7280_pdc_resets[] = {
+	[PDC_APPS_SYNC_RESET] = {0},
+	[PDC_SP_SYNC_RESET] = {1},
+	[PDC_AUDIO_SYNC_RESET] = {2},
+	[PDC_SENSORS_SYNC_RESET] = {3},
+	[PDC_AOP_SYNC_RESET] = {4},
+	[PDC_DEBUG_SYNC_RESET] = {5},
+	[PDC_GPU_SYNC_RESET] = {6},
+	[PDC_DISPLAY_SYNC_RESET] = {7},
+	[PDC_COMPUTE_SYNC_RESET] = {8},
+	[PDC_MODEM_SYNC_RESET] = {9},
+	[PDC_WLAN_RF_SYNC_RESET] = {10},
+	[PDC_WPSS_SYNC_RESET] = {11},
+};
+
+static const struct qcom_pdc_reset_desc sc7280_pdc_reset_desc = {
+	.resets = sc7280_pdc_resets,
+	.num_resets = ARRAY_SIZE(sc7280_pdc_resets),
+	.offset = RPMH_SC7280_PDC_SYNC_RESET,
+};
+
+static inline struct qcom_pdc_reset_data *to_qcom_pdc_reset_data(
+				struct reset_controller_dev *rcdev)
+{
+	return container_of(rcdev, struct qcom_pdc_reset_data, rcdev);
+}
+
+static int qcom_pdc_control_assert(struct reset_controller_dev *rcdev,
+					unsigned long idx)
+{
+	struct qcom_pdc_reset_data *data = to_qcom_pdc_reset_data(rcdev);
+	u32 mask = BIT(data->desc->resets[idx].bit);
+
+	return regmap_update_bits(data->regmap, data->desc->offset, mask, mask);
+}
+
+static int qcom_pdc_control_deassert(struct reset_controller_dev *rcdev,
+					unsigned long idx)
+{
+	struct qcom_pdc_reset_data *data = to_qcom_pdc_reset_data(rcdev);
+	u32 mask = BIT(data->desc->resets[idx].bit);
+
+	return regmap_update_bits(data->regmap, data->desc->offset, mask, 0);
+}
+
+static const struct reset_control_ops qcom_pdc_reset_ops = {
+	.assert = qcom_pdc_control_assert,
+	.deassert = qcom_pdc_control_deassert,
+};
+
+static int qcom_pdc_reset_probe(struct platform_device *pdev)
+{
+	const struct qcom_pdc_reset_desc *desc;
+	struct qcom_pdc_reset_data *data;
+	struct device *dev = &pdev->dev;
+	void __iomem *base;
+
+	desc = device_get_match_data(&pdev->dev);
+	if (!desc)
+		return -EINVAL;
+
+	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->desc = desc;
+	base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(base))
+		return PTR_ERR(base);
+
+	data->regmap = devm_regmap_init_mmio(dev, base, &pdc_regmap_config);
+	if (IS_ERR(data->regmap)) {
+		dev_err(dev, "Unable to initialize regmap\n");
+		return PTR_ERR(data->regmap);
+	}
+
+	data->rcdev.owner = THIS_MODULE;
+	data->rcdev.ops = &qcom_pdc_reset_ops;
+	data->rcdev.nr_resets = desc->num_resets;
+	data->rcdev.of_node = dev->of_node;
+
+	return devm_reset_controller_register(dev, &data->rcdev);
+}
+
+static const struct of_device_id qcom_pdc_reset_of_match[] = {
+	{ .compatible = "qcom,sc7280-pdc-global", .data = &sc7280_pdc_reset_desc },
+	{ .compatible = "qcom,sdm845-pdc-global", .data = &sdm845_pdc_reset_desc },
+	{}
+};
+MODULE_DEVICE_TABLE(of, qcom_pdc_reset_of_match);
+
+static struct platform_driver qcom_pdc_reset_driver = {
+	.probe = qcom_pdc_reset_probe,
+	.driver = {
+		.name = "qcom_pdc_reset",
+		.of_match_table = qcom_pdc_reset_of_match,
+	},
+};
+module_platform_driver(qcom_pdc_reset_driver);
+
+MODULE_DESCRIPTION("Qualcomm PDC Reset Driver");
+MODULE_LICENSE("GPL v2");