soc/tegra: Add efuse driver for Tegra

Implement fuse driver for Tegra20, Tegra30, Tegra114 and Tegra124. This
replaces functionality previously provided in arch/arm/mach-tegra, which
is removed in this patch.

While at it, move the only user of the global tegra_revision variable
over to tegra_sku_info.revision and export tegra_fuse_readl() to allow
drivers to read calibration fuses.

Signed-off-by: Peter De Schrijver <pdeschrijver@nvidia.com>
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
diff --git a/Documentation/ABI/testing/sysfs-driver-tegra-fuse b/Documentation/ABI/testing/sysfs-driver-tegra-fuse
new file mode 100644
index 0000000..69f5af6
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-driver-tegra-fuse
@@ -0,0 +1,11 @@
+What:		/sys/devices/*/<our-device>/fuse
+Date:		February 2014
+Contact:	Peter De Schrijver <pdeschrijver@nvidia.com>
+Description:	read-only access to the efuses on Tegra20, Tegra30, Tegra114
+		and Tegra124 SoC's from NVIDIA. The efuses contain write once
+		data programmed at the factory. The data is layed out in 32bit
+		words in LSB first format. Each bit represents a single value
+		as decoded from the fuse registers. Bits order/assignment
+		exactly matches the HW registers, including any unused bits.
+Users:		any user space application which wants to read the efuses on
+		Tegra SoC's