drivers/base: cpu: Add node for cpu isolation

Add a new per-cpu node to control isolation of CPU.

Usage:
echo 1 > isolate - Isolate the core
echo 0 > isolate - Unisolate the core

Change-Id: I6a13e8dda99130ca794e5b6f51600f4c57a3e921
Signed-off-by: Olav Haugan <ohaugan@codeaurora.org>

1 files changed, 58 insertions, 0 deletions

diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c
index dee022638fe6..c8bfb6077224 100644
--- a/drivers/base/cpu.c
+++ b/drivers/base/cpu.c
@@ -180,6 +180,58 @@ static struct attribute_group crash_note_cpu_attr_group = {
 };
 #endif
 
+#ifdef CONFIG_HOTPLUG_CPU
+
+static ssize_t show_cpu_isolated(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	struct cpu *cpu = container_of(dev, struct cpu, dev);
+	ssize_t rc;
+	int cpuid = cpu->dev.id;
+	unsigned int isolated = cpu_isolated(cpuid);
+
+	rc = snprintf(buf, PAGE_SIZE-2, "%d\n", isolated);
+
+	return rc;
+}
+
+static ssize_t __ref store_cpu_isolated(struct device *dev,
+				struct device_attribute *attr,
+				const char *buf, size_t count)
+{
+	struct cpu *cpu = container_of(dev, struct cpu, dev);
+	int err;
+	int cpuid = cpu->dev.id;
+	unsigned int isolated;
+
+	err = kstrtouint(strstrip((char *)buf), 0, &isolated);
+	if (err)
+		return err;
+
+	if (isolated > 1)
+		return -EINVAL;
+
+	if (isolated)
+		sched_isolate_cpu(cpuid);
+	else
+		sched_unisolate_cpu(cpuid);
+
+	return count;
+}
+
+static DEVICE_ATTR(isolate, 0644, show_cpu_isolated, store_cpu_isolated);
+
+static struct attribute *cpu_isolated_attrs[] = {
+	&dev_attr_isolate.attr,
+	NULL
+};
+
+static struct attribute_group cpu_isolated_attr_group = {
+	.attrs = cpu_isolated_attrs,
+};
+
+#endif
+
 #ifdef CONFIG_SCHED_HMP
 
 static ssize_t show_sched_static_cpu_pwr_cost(struct device *dev,
@@ -280,6 +332,9 @@ static const struct attribute_group *common_cpu_attr_groups[] = {
 #ifdef CONFIG_SCHED_HMP
 	&sched_hmp_cpu_attr_group,
 #endif
+#ifdef CONFIG_HOTPLUG_CPU
+	&cpu_isolated_attr_group,
+#endif
 	NULL
 };
 
@@ -290,6 +345,9 @@ static const struct attribute_group *hotplugable_cpu_attr_groups[] = {
 #ifdef CONFIG_SCHED_HMP
 	&sched_hmp_cpu_attr_group,
 #endif
+#ifdef CONFIG_HOTPLUG_CPU
+	&cpu_isolated_attr_group,
+#endif
 	NULL
 };