soc/tegra: fuse: Implement tegra_is_silicon()

This function can be used by drivers to determine whether code is
running on silicon or on a simulation platform.
Reviewed-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

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

@@ -52,6 +52,25 @@ u8 tegra_get_platform(void)
 	return (tegra_read_chipid() >> 20) & 0xf;
 }
 
+bool tegra_is_silicon(void)
+{
+	switch (tegra_get_chip_id()) {
+	case TEGRA194:
+		if (tegra_get_platform() == 0)
+			return true;
+
+		return false;
+	}
+
+	/*
+	 * Chips prior to Tegra194 have a different way of determining whether
+	 * they are silicon or not. Since we never supported simulation on the
+	 * older Tegra chips, don't bother extracting the information and just
+	 * report that we're running on silicon.
+	 */
+	return true;
+}
+
 u32 tegra_read_straps(void)
 {
 	WARN(!chipid, "Tegra ABP MISC not yet available\n");

include/soc/tegra/fuse.h

@@ -24,6 +24,7 @@
 u32 tegra_read_chipid(void);
 u8 tegra_get_chip_id(void);
 u8 tegra_get_platform(void);
+bool tegra_is_silicon(void);
 
 enum tegra_revision {
 	TEGRA_REVISION_UNKNOWN = 0,