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, 131 insertions, 0 deletions

diff --git a/arch/mips/bcm63xx/dev-flash.c b/arch/mips/bcm63xx/dev-flash.c
new file mode 100644
index 000000000..f9cc015d3
--- /dev/null
+++ b/arch/mips/bcm63xx/dev-flash.c
@@ -0,0 +1,131 @@
+/*
+ * Broadcom BCM63xx flash registration
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 2008 Maxime Bizon <mbizon@freebox.fr>
+ * Copyright (C) 2008 Florian Fainelli <florian@openwrt.org>
+ * Copyright (C) 2012 Jonas Gorski <jonas.gorski@gmail.com>
+ */
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/platform_device.h>
+#include <linux/mtd/mtd.h>
+#include <linux/mtd/partitions.h>
+#include <linux/mtd/physmap.h>
+
+#include <bcm63xx_cpu.h>
+#include <bcm63xx_dev_flash.h>
+#include <bcm63xx_regs.h>
+#include <bcm63xx_io.h>
+
+static struct mtd_partition mtd_partitions[] = {
+	{
+		.name		= "cfe",
+		.offset		= 0x0,
+		.size		= 0x40000,
+	}
+};
+
+static const char *bcm63xx_part_types[] = { "bcm63xxpart", NULL };
+
+static struct physmap_flash_data flash_data = {
+	.width			= 2,
+	.parts			= mtd_partitions,
+	.part_probe_types	= bcm63xx_part_types,
+};
+
+static struct resource mtd_resources[] = {
+	{
+		.start		= 0,	/* filled at runtime */
+		.end		= 0,	/* filled at runtime */
+		.flags		= IORESOURCE_MEM,
+	}
+};
+
+static struct platform_device mtd_dev = {
+	.name			= "physmap-flash",
+	.resource		= mtd_resources,
+	.num_resources		= ARRAY_SIZE(mtd_resources),
+	.dev			= {
+		.platform_data	= &flash_data,
+	},
+};
+
+static int __init bcm63xx_detect_flash_type(void)
+{
+	u32 val;
+
+	switch (bcm63xx_get_cpu_id()) {
+	case BCM6328_CPU_ID:
+		val = bcm_misc_readl(MISC_STRAPBUS_6328_REG);
+		if (val & STRAPBUS_6328_BOOT_SEL_SERIAL)
+			return BCM63XX_FLASH_TYPE_SERIAL;
+		else
+			return BCM63XX_FLASH_TYPE_NAND;
+	case BCM6338_CPU_ID:
+	case BCM6345_CPU_ID:
+	case BCM6348_CPU_ID:
+		/* no way to auto detect so assume parallel */
+		return BCM63XX_FLASH_TYPE_PARALLEL;
+	case BCM3368_CPU_ID:
+	case BCM6358_CPU_ID:
+		val = bcm_gpio_readl(GPIO_STRAPBUS_REG);
+		if (val & STRAPBUS_6358_BOOT_SEL_PARALLEL)
+			return BCM63XX_FLASH_TYPE_PARALLEL;
+		else
+			return BCM63XX_FLASH_TYPE_SERIAL;
+	case BCM6362_CPU_ID:
+		val = bcm_misc_readl(MISC_STRAPBUS_6362_REG);
+		if (val & STRAPBUS_6362_BOOT_SEL_SERIAL)
+			return BCM63XX_FLASH_TYPE_SERIAL;
+		else
+			return BCM63XX_FLASH_TYPE_NAND;
+	case BCM6368_CPU_ID:
+		val = bcm_gpio_readl(GPIO_STRAPBUS_REG);
+		switch (val & STRAPBUS_6368_BOOT_SEL_MASK) {
+		case STRAPBUS_6368_BOOT_SEL_NAND:
+			return BCM63XX_FLASH_TYPE_NAND;
+		case STRAPBUS_6368_BOOT_SEL_SERIAL:
+			return BCM63XX_FLASH_TYPE_SERIAL;
+		case STRAPBUS_6368_BOOT_SEL_PARALLEL:
+			return BCM63XX_FLASH_TYPE_PARALLEL;
+		}
+		fallthrough;
+	default:
+		return -EINVAL;
+	}
+}
+
+int __init bcm63xx_flash_register(void)
+{
+	int flash_type;
+	u32 val;
+
+	flash_type = bcm63xx_detect_flash_type();
+
+	switch (flash_type) {
+	case BCM63XX_FLASH_TYPE_PARALLEL:
+		/* read base address of boot chip select (0) */
+		val = bcm_mpi_readl(MPI_CSBASE_REG(0));
+		val &= MPI_CSBASE_BASE_MASK;
+
+		mtd_resources[0].start = val;
+		mtd_resources[0].end = 0x1FFFFFFF;
+
+		return platform_device_register(&mtd_dev);
+	case BCM63XX_FLASH_TYPE_SERIAL:
+		pr_warn("unsupported serial flash detected\n");
+		return -ENODEV;
+	case BCM63XX_FLASH_TYPE_NAND:
+		pr_warn("unsupported NAND flash detected\n");
+		return -ENODEV;
+	default:
+		pr_err("flash detection failed for BCM%x: %d\n",
+		       bcm63xx_get_cpu_id(), flash_type);
+		return -ENODEV;
+	}
+}