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, 43 insertions, 0 deletions

diff --git a/drivers/usb/phy/of.c b/drivers/usb/phy/of.c
new file mode 100644
index 000000000..1ab134f45
--- /dev/null
+++ b/drivers/usb/phy/of.c
@@ -0,0 +1,43 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * USB of helper code
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/usb/of.h>
+#include <linux/usb/otg.h>
+
+static const char *const usbphy_modes[] = {
+	[USBPHY_INTERFACE_MODE_UNKNOWN]	= "",
+	[USBPHY_INTERFACE_MODE_UTMI]	= "utmi",
+	[USBPHY_INTERFACE_MODE_UTMIW]	= "utmi_wide",
+	[USBPHY_INTERFACE_MODE_ULPI]	= "ulpi",
+	[USBPHY_INTERFACE_MODE_SERIAL]	= "serial",
+	[USBPHY_INTERFACE_MODE_HSIC]	= "hsic",
+};
+
+/**
+ * of_usb_get_phy_mode - Get phy mode for given device_node
+ * @np:	Pointer to the given device_node
+ *
+ * The function gets phy interface string from property 'phy_type',
+ * and returns the corresponding enum usb_phy_interface
+ */
+enum usb_phy_interface of_usb_get_phy_mode(struct device_node *np)
+{
+	const char *phy_type;
+	int err, i;
+
+	err = of_property_read_string(np, "phy_type", &phy_type);
+	if (err < 0)
+		return USBPHY_INTERFACE_MODE_UNKNOWN;
+
+	for (i = 0; i < ARRAY_SIZE(usbphy_modes); i++)
+		if (!strcmp(phy_type, usbphy_modes[i]))
+			return i;
+
+	return USBPHY_INTERFACE_MODE_UNKNOWN;
+}
+EXPORT_SYMBOL_GPL(of_usb_get_phy_mode);