[PATCH v2 5/7] arm: a37xx: pci: Fix a3700_fdt_fix_pcie_regions() function

[Pali Rohár]

Current version of this function uses a lot of incorrect assumptions about
the `ranges` DT property:

 * parent(#address-cells) == 2
 * #size-cells == 2
 * number of entries == 2
 * address size of first entry == 0x1000000
 * second child address entry == base + 0x1000000

Trying to increase PCIe MEM space to more than 16 MiB leads to an overlap
with PCIe IO space, and trying to define additional MEM space (as a third
entry in the `ranges` DT property) causes U-Boot to crash when booting the
kernel.

  ## Flattened Device Tree blob at 04f00000
     Booting using the fdt blob at 0x4f00000
     Loading Device Tree to 000000001fb01000, end 000000001fb08f12 ... OK
  ERROR: board-specific fdt fixup failed: <unknown error>
   - must RESET the board to recover.

Fix a3700_fdt_fix_pcie_regions() to properly parse and update all addresses
in the `ranges` property according to
https://elinux.org/Device_Tree_Usage#PCI_Address_Translation

Now it is possible to increase PCIe MEM space from 16 MiB to maximal value
of 127 MiB.

Signed-off-by: Pali Rohár <pali at kernel.org>
Reviewed-by: Marek Behún <marek.behun at nic.cz>
Fixes: cb2ddb291ee6 ("arm64: mvebu: a37xx: add device-tree fixer for PCIe regions")
---
 arch/arm/mach-mvebu/armada3700/cpu.c | 74 ++++++++++++++++++++++------
 1 file changed, 60 insertions(+), 14 deletions(-)

diff --git a/arch/arm/mach-mvebu/armada3700/cpu.c b/arch/arm/mach-mvebu/armada3700/cpu.c
index 1abac7c9a47a..9aec0ce9a430 100644
--- a/arch/arm/mach-mvebu/armada3700/cpu.c
+++ b/arch/arm/mach-mvebu/armada3700/cpu.c
@@ -8,6 +8,7 @@
 #include <cpu_func.h>
 #include <dm.h>
 #include <fdtdec.h>
+#include <fdt_support.h>
 #include <init.h>
 #include <asm/global_data.h>
 #include <linux/bitops.h>
@@ -280,36 +281,81 @@ static u32 find_pcie_window_base(void)
 	return -1;
 }
 
+static int fdt_setprop_inplace_u32_partial(void *blob, int node,
+					   const char *name,
+					   u32 idx, u32 val)
+{
+	val = cpu_to_fdt32(val);
+
+	return fdt_setprop_inplace_namelen_partial(blob, node, name,
+						   strlen(name),
+						   idx * sizeof(u32),
+						   &val, sizeof(u32));
+}
+
 int a3700_fdt_fix_pcie_regions(void *blob)
 {
-	u32 new_ranges[14], base;
+	int acells, pacells, scells;
+	u32 base, fix_offset;
 	const u32 *ranges;
-	int node, len;
+	int node, pnode;
+	int ret, i, len;
+
+	base = find_pcie_window_base();
+	if (base == -1)
+		return -ENOENT;
 
 	node = fdt_node_offset_by_compatible(blob, -1, "marvell,armada-3700-pcie");
 	if (node < 0)
 		return node;
 
 	ranges = fdt_getprop(blob, node, "ranges", &len);
-	if (!ranges)
+	if (!ranges || len % sizeof(u32))
 		return -ENOENT;
 
-	if (len != sizeof(new_ranges))
-		return -EINVAL;
-
-	memcpy(new_ranges, ranges, len);
+	/*
+	 * The "ranges" property is an array of
+	 * { <child address> <parent address> <size in child address space> }
+	 *
+	 * All 3 elements can span a diffent number of cells. Fetch their sizes.
+	 */
+	pnode = fdt_parent_offset(blob, node);
+	acells = fdt_address_cells(blob, node);
+	pacells = fdt_address_cells(blob, pnode);
+	scells = fdt_size_cells(blob, node);
 
-	base = find_pcie_window_base();
-	if (base == -1)
+	/* Child PCI addresses always use 3 cells */
+	if (acells != 3)
 		return -ENOENT;
 
-	new_ranges[2] = cpu_to_fdt32(base);
-	new_ranges[4] = new_ranges[2];
+	/* Calculate fixup offset from first child address (in last cell) */
+	fix_offset = base - fdt32_to_cpu(ranges[2]);
 
-	new_ranges[9] = cpu_to_fdt32(base + 0x1000000);
-	new_ranges[11] = new_ranges[9];
+	/*
+	 * Fix address (last cell) of each child address and each parent
+	 * address
+	 */
+	for (i = 0; i < len / sizeof(u32); i += acells + pacells + scells) {
+		int idx;
+
+		/* fix child address */
+		idx = i + acells - 1;
+		ret = fdt_setprop_inplace_u32_partial(blob, node, "ranges", idx,
+						      fdt32_to_cpu(ranges[idx]) +
+						      fix_offset);
+		if (ret)
+			return ret;
+
+		/* fix parent address */
+		idx = i + acells + pacells - 1;
+		ret = fdt_setprop_inplace_u32_partial(blob, node, "ranges", idx,
+						      fdt32_to_cpu(ranges[idx]) +
+						      fix_offset);
+		if (ret)
+			return ret;
+	}
 
-	return fdt_setprop_inplace(blob, node, "ranges", new_ranges, len);
+	return 0;
 }
 
 void reset_cpu(void)
-- 
2.20.1