[PATCH v3 2/3] EDAC/loongson: Get DIMM size from ACPI _DSM method

From: Wang Jinwei <[email protected]>

Add support to retrieve DIMM size from ACPI _DSM method instead
of using hardcoded values.

1. Add loongson_get_dimm_size_acpi() to call ACPI _DSM method
   to Get DIMM size in MB.

2. Update dimm_config_init() to use the size from ACPI, with
   fallback to default 1 MB if ACPI method fails.

3. Add ACPI UUID and DSM function definitions for EDAC.

The DIMM size is passed from UEFI through ACPI OperationRegion
and _DSM method, enabling correct display of memory size in
/sys/devices/system/edac/mc/mc*/size_mb.

Cc: Dongyan Qian <[email protected]>
Cc: Chao Li <[email protected]>
Signed-off-by: Wang Jinwei <[email protected]>
Signed-off-by: Qunqin Zhao <[email protected]>
---
 drivers/edac/loongson_edac.c | 32 ++++++++++++++++++++++++++++++--
 1 file changed, 30 insertions(+), 2 deletions(-)

diff --git a/drivers/edac/loongson_edac.c b/drivers/edac/loongson_edac.c
index 87ac2a3615..a3776a8501 100644
--- a/drivers/edac/loongson_edac.c
+++ b/drivers/edac/loongson_edac.c
@@ -13,6 +13,8 @@
 #include "edac_module.h"
 
 #define ECC_CS_COUNT_REG	0x18
+#define LOONGSON_EDAC_DSM_UUID	"65d0431b-7eb8-46df-b914-b7d568553140"
+#define LOONGSON_EDAC_DSM_FUNC_GET_DIMM_SIZE	1
 
 struct loongson_edac_pvt {
 	void __iomem *ecc_base;
@@ -66,13 +68,39 @@ static void edac_check(struct mem_ctl_info *mci)
 			     0, 0, 0, 0, 0, -1, "error", other_detail);
 }
 
+static u32 loongson_get_dimm_size_acpi(struct device *dev)
+{
+	acpi_handle handle = ACPI_HANDLE(dev);
+	union acpi_object *obj;
+	u32 size_mb = 1;
+	guid_t guid;
+
+	if (!handle)
+		return size_mb;
+
+	if (guid_parse(LOONGSON_EDAC_DSM_UUID, &guid))
+		return size_mb;
+
+	obj = acpi_evaluate_dsm(handle, &guid, 0,
+				LOONGSON_EDAC_DSM_FUNC_GET_DIMM_SIZE, NULL);
+	if (!obj)
+		return size_mb;
+
+	if (obj->type == ACPI_TYPE_INTEGER)
+		size_mb = (u32)obj->integer.value;
+
+	ACPI_FREE(obj);
+	return size_mb;
+}
+
 static void dimm_config_init(struct mem_ctl_info *mci)
 {
 	struct dimm_info *dimm;
+	struct device *dev = mci->pdev;
 	u32 size, npages;
 
-	/* size not used */
-	size = -1;
+	size = loongson_get_dimm_size_acpi(dev);
+
 	npages = MiB_TO_PAGES(size);
 
 	dimm = edac_get_dimm(mci, 0, 0, 0);
-- 
2.47.3