[PATCH] of/fdt: Allow memory node and root to have different size/address cells

[PATCH] of/fdt: Allow memory node and root to have different size/address cells

[Vineet Gupta]

Currently memory node parsing uses root "#size-cells", "#address-cells"
This doesn't work correctly when memory address/size is different or
greater than root's.

e.g. ARC 32-bit systems implementing physical adressing extension and
say 4GB of memory. All peripherals mappings stay within the 4GB (so root
address/size cells remain 1 each), only the memory node address/size
cells needs to specify greater than 32-bits as below

	memory {
		device_type = "memory";
		reg = <0x0 0x80000000 0x1 0x00000000>;	/* 4 GB */
		#address-cells = <2>;
		#size-cells = <2>;
	};

This patch lets me boot a ARC system with PAE40 + 4GB of memory specified
as above and fails to boot otherwise as memory parsing doesn't populate
right base, size.

Cc: Grant Likely <grant.likely@linaro.org>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: devicetree@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
---
 drivers/of/fdt.c | 21 ++++++++++++++++-----
 1 file changed, 16 insertions(+), 5 deletions(-)

diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index 07496560e5b9..3af808f45965 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -888,8 +888,8 @@ int __init early_init_dt_scan_memory(unsigned long node, const char *uname,
 				     int depth, void *data)
 {
 	const char *type = of_get_flat_dt_prop(node, "device_type", NULL);
-	const __be32 *reg, *endp;
-	int l;
+	const __be32 *reg, *endp, *prop;
+	int l, dt_mem_addr_cells, dt_mem_size_cells;
 
 	/* We are scanning "memory" nodes only */
 	if (type == NULL) {
@@ -912,11 +912,22 @@ int __init early_init_dt_scan_memory(unsigned long node, const char *uname,
 
 	pr_debug("memory scan node %s, reg size %d,\n", uname, l);
 
-	while ((endp - reg) >= (dt_root_addr_cells + dt_root_size_cells)) {
+
+	dt_mem_size_cells = dt_root_size_cells,;
+	prop = of_get_flat_dt_prop(node, "#size-cells", NULL);
+	if (prop)
+		dt_mem_size_cells = be32_to_cpup(prop);
+
+	dt_mem_addr_cells = dt_root_addr_cells;
+	prop = of_get_flat_dt_prop(node, "#address-cells", NULL);
+	if (prop)
+		dt_mem_addr_cells = be32_to_cpup(prop);
+
+	while ((endp - reg) >= (dt_mem_addr_cells + dt_mem_size_cells)) {
 		u64 base, size;
 
-		base = dt_mem_next_cell(dt_root_addr_cells, &reg);
-		size = dt_mem_next_cell(dt_root_size_cells, &reg);
+		base = dt_mem_next_cell(dt_mem_addr_cells, &reg);
+		size = dt_mem_next_cell(dt_mem_size_cells, &reg);
 
 		if (size == 0)
 			continue;
-- 
1.9.1

Re: [PATCH] of/fdt: Allow memory node and root to have different size/address cells

[kbuild test robot]

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Hi Vineet,

[auto build test results on v4.3-rc3 -- if it's inappropriate base, please ignore]

config: i386-randconfig-i1-201539 (attached as .config)
reproduce:
        git checkout 84881842f801639b80c8f6a0d9afbc582b33be01
        # save the attached .config to linux build tree
        make ARCH=i386 

All error/warnings (new ones prefixed by >>):

   drivers/of/fdt.c: In function 'early_init_dt_scan_memory':
>> drivers/of/fdt.c:916:41: error: expected expression before ';' token
     dt_mem_size_cells = dt_root_size_cells,;
                                            ^

vim +916 drivers/of/fdt.c

   910	
   911		endp = reg + (l / sizeof(__be32));
   912	
   913		pr_debug("memory scan node %s, reg size %d,\n", uname, l);
   914	
   915	
 > 916		dt_mem_size_cells = dt_root_size_cells,;
   917		prop = of_get_flat_dt_prop(node, "#size-cells", NULL);
   918		if (prop)
   919			dt_mem_size_cells = be32_to_cpup(prop);

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

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