ARM: OMAP2+: GPMC: Support Software ECC scheme via DT

For v3.14 and prior, 1-bit Hamming code ECC via software was the
default choice for some boards e.g. 3430sdp.
Commit ac65caf5 in v3.15 changed the behaviour
to use 1-bit Hamming code via Hardware using a different ECC layout
i.e. (ROM code layout) than what is used by software ECC.

This ECC layout change causes NAND filesystems created in v3.14
and prior to be unusable in v3.15 and later. So don't mark "sw" scheme
as deperecated and support it.
Signed-off-by: Roger Quadros <rogerq@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

Documentation/devicetree/bindings/mtd/gpmc-nand.txt

@@ -22,7 +22,7 @@ Optional properties:
 				width of 8 is assumed.
 
  - ti,nand-ecc-opt:		A string setting the ECC layout to use. One of:
-		"sw"		<deprecated> use "ham1" instead
+		"sw"		1-bit Hamming ecc code via software
 		"hw"		<deprecated> use "ham1" instead
 		"hw-romcode"	<deprecated> use "ham1" instead
 		"ham1"		1-bit Hamming ecc code

arch/arm/mach-omap2/gpmc.c

@@ -1403,7 +1403,10 @@ static int gpmc_probe_nand_child(struct platform_device *pdev,
 		pr_err("%s: ti,nand-ecc-opt not found\n", __func__);
 		return -ENODEV;
 	}
-	if (!strcmp(s, "ham1") || !strcmp(s, "sw") ||
+
+	if (!strcmp(s, "sw"))
+		gpmc_nand_data->ecc_opt = OMAP_ECC_HAM1_CODE_SW;
+	else if (!strcmp(s, "ham1") ||
 		 !strcmp(s, "hw") || !strcmp(s, "hw-romcode"))
 		gpmc_nand_data->ecc_opt =
 				OMAP_ECC_HAM1_CODE_HW;