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, 170 insertions, 0 deletions

diff --git a/drivers/mfd/max7360.c b/drivers/mfd/max7360.c
new file mode 100644
index 000000000..52fffed0c
--- /dev/null
+++ b/drivers/mfd/max7360.c
@@ -0,0 +1,170 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Maxim MAX7360 Core Driver
+ *
+ * Copyright 2025 Bootlin
+ *
+ * Authors:
+ *    Kamel Bouhara <kamel.bouhara@bootlin.com>
+ *    Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>
+ */
+
+#include <linux/array_size.h>
+#include <linux/bits.h>
+#include <linux/delay.h>
+#include <linux/device/devres.h>
+#include <linux/dev_printk.h>
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/mfd/core.h>
+#include <linux/mfd/max7360.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+#include <linux/types.h>
+
+static const struct mfd_cell max7360_cells[] = {
+	{ .name           = "max7360-pinctrl" },
+	{ .name           = "max7360-pwm" },
+	{ .name           = "max7360-keypad" },
+	{ .name           = "max7360-rotary" },
+	{
+		.name           = "max7360-gpo",
+		.of_compatible	= "maxim,max7360-gpo",
+	},
+	{
+		.name           = "max7360-gpio",
+		.of_compatible	= "maxim,max7360-gpio",
+	},
+};
+
+static const struct regmap_range max7360_volatile_ranges[] = {
+	regmap_reg_range(MAX7360_REG_KEYFIFO, MAX7360_REG_KEYFIFO),
+	regmap_reg_range(MAX7360_REG_I2C_TIMEOUT, MAX7360_REG_RTR_CNT),
+};
+
+static const struct regmap_access_table max7360_volatile_table = {
+	.yes_ranges = max7360_volatile_ranges,
+	.n_yes_ranges = ARRAY_SIZE(max7360_volatile_ranges),
+};
+
+static const struct regmap_config max7360_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.max_register = MAX7360_REG_PWMCFG(MAX7360_PORT_PWM_COUNT - 1),
+	.volatile_table = &max7360_volatile_table,
+	.cache_type = REGCACHE_MAPLE,
+};
+
+static int max7360_mask_irqs(struct regmap *regmap)
+{
+	struct device *dev = regmap_get_device(regmap);
+	unsigned int val;
+	int ret;
+
+	/*
+	 * GPIO/PWM interrupts are not masked on reset: as the MAX7360 "INTI"
+	 * interrupt line is shared between GPIOs and rotary encoder, this could
+	 * result in repeated spurious interrupts on the rotary encoder driver
+	 * if the GPIO driver is not loaded. Mask them now to avoid this
+	 * situation.
+	 */
+	for (unsigned int i = 0; i < MAX7360_PORT_PWM_COUNT; i++) {
+		ret = regmap_write_bits(regmap, MAX7360_REG_PWMCFG(i),
+					MAX7360_PORT_CFG_INTERRUPT_MASK,
+					MAX7360_PORT_CFG_INTERRUPT_MASK);
+		if (ret)
+			return dev_err_probe(dev, ret,
+					     "Failed to write MAX7360 port configuration\n");
+	}
+
+	/* Read GPIO in register, to ACK any pending IRQ. */
+	ret = regmap_read(regmap, MAX7360_REG_GPIOIN, &val);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to read GPIO values\n");
+
+	return 0;
+}
+
+static int max7360_reset(struct regmap *regmap)
+{
+	struct device *dev = regmap_get_device(regmap);
+	int ret;
+
+	ret = regmap_write(regmap, MAX7360_REG_GPIOCFG, MAX7360_GPIO_CFG_GPIO_RST);
+	if (ret) {
+		dev_err(dev, "Failed to reset GPIO configuration: %x\n", ret);
+		return ret;
+	}
+
+	ret = regcache_drop_region(regmap, MAX7360_REG_GPIOCFG, MAX7360_REG_GPIO_LAST);
+	if (ret) {
+		dev_err(dev, "Failed to drop regmap cache: %x\n", ret);
+		return ret;
+	}
+
+	ret = regmap_write(regmap, MAX7360_REG_SLEEP, 0);
+	if (ret) {
+		dev_err(dev, "Failed to reset autosleep configuration: %x\n", ret);
+		return ret;
+	}
+
+	ret = regmap_write(regmap, MAX7360_REG_DEBOUNCE, 0);
+	if (ret)
+		dev_err(dev, "Failed to reset GPO port count: %x\n", ret);
+
+	return ret;
+}
+
+static int max7360_probe(struct i2c_client *client)
+{
+	struct device *dev = &client->dev;
+	struct regmap *regmap;
+	int ret;
+
+	regmap = devm_regmap_init_i2c(client, &max7360_regmap_config);
+	if (IS_ERR(regmap))
+		return dev_err_probe(dev, PTR_ERR(regmap), "Failed to initialise regmap\n");
+
+	ret = max7360_reset(regmap);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to reset device\n");
+
+	/* Get the device out of shutdown mode. */
+	ret = regmap_write_bits(regmap, MAX7360_REG_GPIOCFG,
+				MAX7360_GPIO_CFG_GPIO_EN,
+				MAX7360_GPIO_CFG_GPIO_EN);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to enable GPIO and PWM module\n");
+
+	ret = max7360_mask_irqs(regmap);
+	if (ret)
+		return dev_err_probe(dev, ret, "Could not mask interrupts\n");
+
+	ret = devm_mfd_add_devices(dev, PLATFORM_DEVID_NONE,
+				   max7360_cells, ARRAY_SIZE(max7360_cells),
+				   NULL, 0, NULL);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to register child devices\n");
+
+	return 0;
+}
+
+static const struct of_device_id max7360_dt_match[] = {
+	{ .compatible = "maxim,max7360" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, max7360_dt_match);
+
+static struct i2c_driver max7360_driver = {
+	.driver = {
+		.name = "max7360",
+		.of_match_table = max7360_dt_match,
+	},
+	.probe = max7360_probe,
+};
+module_i2c_driver(max7360_driver);
+
+MODULE_DESCRIPTION("Maxim MAX7360 I2C IO Expander core driver");
+MODULE_AUTHOR("Kamel Bouhara <kamel.bouhara@bootlin.com>");
+MODULE_LICENSE("GPL");