riscv: add ZONE_DMA32

This patch allows devices that require memory that can be addressed
using 32-bit addresses to work easily on RISC-V systems.  The newly
improved dma-direct ops will tap into this pool automatically for
32-bit addressing.

Based on an earlier patch from Wesley W. Terpstra.

CC: Wesley W. Terpstra <terpstra@sifive.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c
index c6d095ff5ab8..09f7064e898c 100644
--- a/arch/riscv/kernel/setup.c
+++ b/arch/riscv/kernel/setup.c
@@ -181,6 +181,15 @@ static void __init setup_bootmem(void)
 	early_init_fdt_scan_reserved_mem();
 	memblock_allow_resize();
 	memblock_dump_all();
+
+	for_each_memblock(memory, reg) {
+		unsigned long start_pfn = memblock_region_memory_base_pfn(reg);
+		unsigned long end_pfn = memblock_region_memory_end_pfn(reg);
+
+		memblock_set_node(PFN_PHYS(start_pfn),
+		                  PFN_PHYS(end_pfn - start_pfn),
+		                  &memblock.memory, 0);
+	}
 }
 
 void __init setup_arch(char **cmdline_p)