[PATCH 1/5] ARM: bL_switcher: Don't enable bL switcher on systems without CCI

[Abhilash Kesavan]

From: Andrew Bresticker <abrestic at chromium.org>

Do not enable the big.LITTLE switcher on systems that do not have an
ARM CCI (cache-coherent interconnect) present.  Since the CCI is used
to maintain cache coherency between multiple clusters and peripherals,
it is unlikely that a system without CCI would support big.LITTLE.

Signed-off-by: Andrew Bresticker <abrestic at chromium.org>
Signed-off-by: Abhilash Kesavan <a.kesavan at samsung.com>
---
 arch/arm/common/bL_switcher.c |   12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/arch/arm/common/bL_switcher.c b/arch/arm/common/bL_switcher.c
index 5774b6e..c4fec1f 100644
--- a/arch/arm/common/bL_switcher.c
+++ b/arch/arm/common/bL_switcher.c
@@ -33,6 +33,7 @@
 #include <linux/sysfs.h>
 #include <linux/irqchip/arm-gic.h>
 #include <linux/moduleparam.h>
+#include <linux/of.h>
 
 #include <asm/smp_plat.h>
 #include <asm/cputype.h>
@@ -796,6 +797,17 @@ core_param(no_bL_switcher, no_bL_switcher, bool, 0644);
 static int __init bL_switcher_init(void)
 {
 	int ret;
+	struct device_node *dn;
+
+	/*
+	 * We don't want to set up the bL switcher if the machine doesn't
+	 * support bL, so use the presence of a CCI to indicate whether or
+	 * not bL is supported on this device.
+	 */
+	dn = of_find_compatible_node(NULL, NULL, "arm,cci-400");
+	if (!dn)
+		return 0;
+	of_node_put(dn);
 
 	if (MAX_NR_CLUSTERS != 2) {
 		pr_err("%s: only dual cluster systems are supported\n", __func__);
-- 
1.7.9.5