Re: [PATCH V3 21/22] LoongArch: Add Non-Uniform Memory Access (NUMA) support

+/*
+ * We extract 4bit node id (bit 44~47) from Loongson-3's
+ * 48bit physical address space and embed it into 40bit.
+ */
+
+static int node_id_offset;
+
+static dma_addr_t loongson_phys_to_dma(struct device *dev, phys_addr_t paddr)
+{
+	long nid = (paddr >> 44) & 0xf;
+
+	return ((nid << 44) ^ paddr) | (nid << node_id_offset);
+}
+
+static phys_addr_t loongson_dma_to_phys(struct device *dev, dma_addr_t daddr)
+{
+	long nid = (daddr >> node_id_offset) & 0xf;
+
+	return ((nid << node_id_offset) ^ daddr) | (nid << 44);
+}
+
+static struct loongson_addr_xlate_ops {
+	dma_addr_t (*phys_to_dma)(struct device *dev, phys_addr_t paddr);
+	phys_addr_t (*dma_to_phys)(struct device *dev, dma_addr_t daddr);
+} xlate_ops;
+
+dma_addr_t phys_to_dma(struct device *dev, phys_addr_t paddr)
+{
+	return xlate_ops.phys_to_dma(dev, paddr);
+}
+
+phys_addr_t dma_to_phys(struct device *dev, dma_addr_t daddr)
+{
+	return xlate_ops.dma_to_phys(dev, daddr);
+}