MIPS: Loongson-3: Add PHYS48_TO_HT40 support
The width of HT-bus is only 40-bit, but Loongson-3 has 48-bit physical
address. This implies only node-0's memory is DMAable because high bits
(Node ID) will lost. Fortunately, by configuring address windows in
firmware, we can extract 2bit Node ID (bit 44~47, only bit 44~45 used
now) from Loongson-3's 48-bit address space and embed it into 40-bit
(bit 37~38). Every NUMA node can do DMA now (however, maximum memory of
each node is reduced to 2^37 = 128GB).
Signed-off-by: Huacai Chen <chenhc@lemote.com>
Cc: John Crispin <john@phrozen.org>
Cc: Steven J. Hill <Steven.Hill@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: Fuxin Zhang <zhangfx@lemote.com>
Cc: Zhangjin Wu <wuzhangjin@gmail.com>
Patchwork: https://patchwork.linux-mips.org/patch/8321/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/loongson/common/dma-swiotlb.c b/arch/mips/loongson/common/dma-swiotlb.c
index c2be01f..2c6b989 100644
--- a/arch/mips/loongson/common/dma-swiotlb.c
+++ b/arch/mips/loongson/common/dma-swiotlb.c
@@ -105,11 +105,25 @@
dma_addr_t phys_to_dma(struct device *dev, phys_addr_t paddr)
{
+ long nid;
+#ifdef CONFIG_PHYS48_TO_HT40
+ /* We extract 2bit node id (bit 44~47, only bit 44~45 used now) from
+ * Loongson-3's 48bit address space and embed it into 40bit */
+ nid = (paddr >> 44) & 0x3;
+ paddr = ((nid << 44) ^ paddr) | (nid << 37);
+#endif
return paddr;
}
phys_addr_t dma_to_phys(struct device *dev, dma_addr_t daddr)
{
+ long nid;
+#ifdef CONFIG_PHYS48_TO_HT40
+ /* We extract 2bit node id (bit 44~47, only bit 44~45 used now) from
+ * Loongson-3's 48bit address space and embed it into 40bit */
+ nid = (daddr >> 37) & 0x3;
+ daddr = ((nid << 37) ^ daddr) | (nid << 44);
+#endif
return daddr;
}