ARM: 8032/1: bL_switcher: fix validation check before its activation

The switcher should not depend on MAX_CLUSTER to determine ifit should
be activated or not. In a multiplatform kernel binary it is possible to
have dual-cluster and quad-cluster platforms configured in. In that case
MAX_CLUSTER which is a build time limit should be 4 and that shouldn't
prevent the switcher from working if the kernel is booted on a b.L
dual-cluster system.

In bL_switcher_halve_cpus() we already have a runtime validation check
to make sure we're dealing with only two clusters, so booting on a quad
cluster system will be caught and switcher activation aborted.

However, the b.L switcher must ensure the MCPM layer is initialized on
the booted hardware before doing anything.  The mcpm_is_available()
function is added to that effect.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
Tested-by: Abhilash Kesavan <kesavan.abhilash@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

diff --git a/arch/arm/common/bL_switcher.c b/arch/arm/common/bL_switcher.c
index 5774b6ea7ad55ab0e6c56a5239c475f00a9feb32..f01c0ee0c87ebd94debc320f5714bf247dfe5ab7 100644 (file)
--- a/arch/arm/common/bL_switcher.c
+++ b/arch/arm/common/bL_switcher.c
@@ -797,10 +797,8 @@ static int __init bL_switcher_init(void)
 {
        int ret;
 
-       if (MAX_NR_CLUSTERS != 2) {
-               pr_err("%s: only dual cluster systems are supported\n", __func__);
-               return -EINVAL;
-       }
+       if (!mcpm_is_available())
+               return -ENODEV;
 
        cpu_notifier(bL_switcher_hotplug_callback, 0);
 

diff --git a/arch/arm/common/mcpm_entry.c b/arch/arm/common/mcpm_entry.c
index 1e361abc29eb0e106492223348de051d1e4e9f3d..86fd60fefbc935a788b52bdf8701efebbe5d5f8d 100644 (file)
--- a/arch/arm/common/mcpm_entry.c
+++ b/arch/arm/common/mcpm_entry.c
@@ -48,6 +48,11 @@ int __init mcpm_platform_register(const struct mcpm_platform_ops *ops)
        return 0;
 }
 
+bool mcpm_is_available(void)
+{
+       return (platform_ops) ? true : false;
+}
+
 int mcpm_cpu_power_up(unsigned int cpu, unsigned int cluster)
 {
        if (!platform_ops)

diff --git a/arch/arm/include/asm/mcpm.h b/arch/arm/include/asm/mcpm.h
index 608516ebabfe6111a651f3a5ca6e63c607046fab..a5ff410dcdb6a47a03a03214bcc0d66fdc33da94 100644 (file)
--- a/arch/arm/include/asm/mcpm.h
+++ b/arch/arm/include/asm/mcpm.h
@@ -53,6 +53,13 @@ void mcpm_set_early_poke(unsigned cpu, unsigned cluster,
  * CPU/cluster power operations API for higher subsystems to use.
  */
 
+/**
+ * mcpm_is_available - returns whether MCPM is initialized and available
+ *
+ * This returns true or false accordingly.
+ */
+bool mcpm_is_available(void);
+
 /**
  * mcpm_cpu_power_up - make given CPU in given cluster runable
  *