ARM: tegra: RAM code access for v4.2-rc1

The RAM code is used by the memory and external memory controllers to
 determine which set of timings to use for memory frequency scaling.
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Merge tag 'tegra-for-4.2-ramcode' of git://git.kernel.org/pub/scm/linux/kernel/git/tegra/linux into next/drivers

Merge "ARM: tegra: RAM code access for v4.2-rc1" from Thierry Reding:

The RAM code is used by the memory and external memory controllers to
determine which set of timings to use for memory frequency scaling.

* tag 'tegra-for-4.2-ramcode' of git://git.kernel.org/pub/scm/linux/kernel/git/tegra/linux:
  soc/tegra: fuse: Add RAM code reader helper
  of: Document long-ram-code property in nvidia,tegra20-apbmisc

Documentation/devicetree/bindings/misc/nvidia,tegra20-apbmisc.txt

@@ -10,3 +10,5 @@ Required properties:
        The second entry gives the physical address and length of the
        registers indicating the strapping options.
 
+Optional properties:
+- nvidia,long-ram-code: If present, the RAM code is long (4 bit). If not, short (2 bit).

drivers/soc/tegra/fuse/tegra-apbmisc.c

@@ -28,8 +28,15 @@
 #define APBMISC_SIZE	0x64
 #define FUSE_SKU_INFO	0x10
 
+#define PMC_STRAPPING_OPT_A_RAM_CODE_SHIFT	4
+#define PMC_STRAPPING_OPT_A_RAM_CODE_MASK_LONG	\
+	(0xf << PMC_STRAPPING_OPT_A_RAM_CODE_SHIFT)
+#define PMC_STRAPPING_OPT_A_RAM_CODE_MASK_SHORT	\
+	(0x3 << PMC_STRAPPING_OPT_A_RAM_CODE_SHIFT)
+
 static void __iomem *apbmisc_base;
 static void __iomem *strapping_base;
+static bool long_ram_code;
 
 u32 tegra_read_chipid(void)
 {
@@ -54,6 +61,18 @@ u32 tegra_read_straps(void)
 		return 0;
 }
 
+u32 tegra_read_ram_code(void)
+{
+	u32 straps = tegra_read_straps();
+
+	if (long_ram_code)
+		straps &= PMC_STRAPPING_OPT_A_RAM_CODE_MASK_LONG;
+	else
+		straps &= PMC_STRAPPING_OPT_A_RAM_CODE_MASK_SHORT;
+
+	return straps >> PMC_STRAPPING_OPT_A_RAM_CODE_SHIFT;
+}
+
 static const struct of_device_id apbmisc_match[] __initconst = {
 	{ .compatible = "nvidia,tegra20-apbmisc", },
 	{},
@@ -112,4 +131,6 @@ void __init tegra_init_apbmisc(void)
 	strapping_base = of_iomap(np, 1);
 	if (!strapping_base)
 		pr_err("ioremap tegra strapping_base failed\n");
+
+	long_ram_code = of_property_read_bool(np, "nvidia,long-ram-code");
 }

include/soc/tegra/fuse.h

@@ -56,6 +56,7 @@ struct tegra_sku_info {
 };
 
 u32 tegra_read_straps(void);
+u32 tegra_read_ram_code(void);
 u32 tegra_read_chipid(void);
 int tegra_fuse_readl(unsigned long offset, u32 *value);