ARM: tegra: only run PL310 init on systems with one

Fix tegra_init_cache() to check whether the system has a PL310 cache
before touching the PL310 registers. This prevents access to non-existent
registers on Tegra114 and later.

Note for stable kernels:
In <= v3.12, the file to patch is arch/arm/mach-tegra/common.c.

Cc: <stable@vger.kernel.org> # v3.9+
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Olof Johansson <olof@lixom.net>

arch/arm/mach-tegra/tegra.c

@@ -73,10 +73,20 @@ u32 tegra_uart_config[3] = {
 static void __init tegra_init_cache(void)
 {
 #ifdef CONFIG_CACHE_L2X0
+	static const struct of_device_id pl310_ids[] __initconst = {
+		{ .compatible = "arm,pl310-cache",  },
+		{}
+	};
+
+	struct device_node *np;
 	int ret;
 	void __iomem *p = IO_ADDRESS(TEGRA_ARM_PERIF_BASE) + 0x3000;
 	u32 aux_ctrl, cache_type;
 
+	np = of_find_matching_node(NULL, pl310_ids);
+	if (!np)
+		return;
+
 	cache_type = readl(p + L2X0_CACHE_TYPE);
 	aux_ctrl = (cache_type & 0x700) << (17-8);
 	aux_ctrl |= 0x7C400001;