drm/amd: Refactor find_system_memory()

find_system_memory() pulls out two fields from an SMBIOS type 17
device and sets them on KFD devices. The data offsets are counted
to find interesting data.

Instead use a struct representation to access the members and pull
out the two specific fields.

No intended functional changes.

Link: https://www.dmtf.org/sites/default/files/standards/documents/DSP0134_3.8.0.pdf p99
Reviewed-by: Felix Kuehling <felix.kuehling@amd.com>
Link: https://lore.kernel.org/r/20250206214847.3334595-1-superm1@kernel.org
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

2 files changed, 30 insertions, 14 deletions

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_topology.c b/drivers/gpu/drm/amd/amdkfd/kfd_topology.c
index 4936697e6fc2..28516ae96832 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_topology.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_topology.c
@@ -950,24 +950,23 @@ static void kfd_update_system_properties(void)
 	up_read(&topology_lock);
 }
 
-static void find_system_memory(const struct dmi_header *dm,
-	void *private)
+static void find_system_memory(const struct dmi_header *dm, void *private)
 {
+	struct dmi_mem_device *memdev = container_of(dm, struct dmi_mem_device, header);
 	struct kfd_mem_properties *mem;
-	u16 mem_width, mem_clock;
 	struct kfd_topology_device *kdev =
 		(struct kfd_topology_device *)private;
-	const u8 *dmi_data = (const u8 *)(dm + 1);
-
-	if (dm->type == DMI_ENTRY_MEM_DEVICE && dm->length >= 0x15) {
-		mem_width = (u16)(*(const u16 *)(dmi_data + 0x6));
-		mem_clock = (u16)(*(const u16 *)(dmi_data + 0x11));
-		list_for_each_entry(mem, &kdev->mem_props, list) {
-			if (mem_width != 0xFFFF && mem_width != 0)
-				mem->width = mem_width;
-			if (mem_clock != 0)
-				mem->mem_clk_max = mem_clock;
-		}
+
+	if (memdev->header.type != DMI_ENTRY_MEM_DEVICE)
+		return;
+	if (memdev->header.length < sizeof(struct dmi_mem_device))
+		return;
+
+	list_for_each_entry(mem, &kdev->mem_props, list) {
+		if (memdev->total_width != 0xFFFF && memdev->total_width != 0)
+			mem->width = memdev->total_width;
+		if (memdev->speed != 0)
+			mem->mem_clk_max = memdev->speed;
 	}
 }
 
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_topology.h b/drivers/gpu/drm/amd/amdkfd/kfd_topology.h
index 155b5c410af1..f06c9db7ddde 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_topology.h
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_topology.h
@@ -24,6 +24,7 @@
 #ifndef __KFD_TOPOLOGY_H__
 #define __KFD_TOPOLOGY_H__
 
+#include <linux/dmi.h>
 #include <linux/types.h>
 #include <linux/list.h>
 #include <linux/kfd_sysfs.h>
@@ -179,6 +180,22 @@ struct kfd_system_properties {
 	struct attribute	attr_props;
 };
 
+struct dmi_mem_device {
+	struct dmi_header header;
+	u16 physical_handle;
+	u16 error_handle;
+	u16 total_width;
+	u16 data_width;
+	u16 size;
+	u8 form_factor;
+	u8 device_set;
+	u8 device_locator;
+	u8 bank_locator;
+	u8 memory_type;
+	u16 type_detail;
+	u16 speed;
+} __packed;
+
 struct kfd_topology_device *kfd_create_topology_device(
 		struct list_head *device_list);
 void kfd_release_topology_device_list(struct list_head *device_list);