Intel: cpuidle: Allow idle states to be disabled by default

task #29239886

commit 75a80267410e38ab76c4ceb39753f96d72113781 upstream

In certain situations it may be useful to prevent some idle states
from being used by default while allowing user space to enable them
later on.

For this purpose, introduce a new state flag, CPUIDLE_FLAG_OFF, to
mark idle states that should be disabled by default, make the core
set CPUIDLE_STATE_DISABLED_BY_USER for those states at the
initialization time and add a new state attribute in sysfs,
"default_status", to inform user space of the initial status of
the given idle state ("disabled" if CPUIDLE_FLAG_OFF is set for it,
"enabled" otherwise).
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Nyjia <yingbao.jia@intel.com>
Signed-off-by: NErwei Deng <erwei@linux.alibaba.com>
Reviewed-by: NArtie Ding <artie.ding@linux.alibaba.com>

Documentation/ABI/testing/sysfs-devices-system-cpu

@@ -188,6 +188,12 @@ Description:
 		does not reflect it. Likewise, if one enables a deep state but a
 		lighter state still is disabled, then this has no effect.
 
+What:		/sys/devices/system/cpu/cpuX/cpuidle/stateN/default_status
+Date:		December 2019
+KernelVersion:	v5.6
+Contact:	Linux power management list <linux-pm@vger.kernel.org>
+Description:
+		(RO) The default status of this state, "enabled" or "disabled".
 
 What:		/sys/devices/system/cpu/cpuX/cpuidle/stateN/residency
 Date:		March 2014

Documentation/admin-guide/pm/cpuidle.rst

@@ -404,6 +404,9 @@ object corresponding to it, as follows:
 ``disable``
 	Whether or not this idle state is disabled.
 
+``default_status``
+	The default status of this state, "enabled" or "disabled".
+
 ``latency``
 	Exit latency of the idle state in microseconds.
 

drivers/cpuidle/cpuidle.c

@@ -523,12 +523,17 @@ static void __cpuidle_device_init(struct cpuidle_device *dev)
  */
 static int __cpuidle_register_device(struct cpuidle_device *dev)
 {
-	int ret;
 	struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
+	int i, ret;
 
 	if (!try_module_get(drv->owner))
 		return -EINVAL;
 
+	for (i = 0; i < drv->state_count; i++) {
+		if (drv->states[i].flags & CPUIDLE_FLAG_OFF)
+			dev->states_usage[i].disable |= CPUIDLE_STATE_DISABLED_BY_USER;
+	}
+
 	per_cpu(cpuidle_devices, dev->cpu) = dev;
 	list_add(&dev->device_list, &cpuidle_detected_devices);
 

drivers/cpuidle/sysfs.c

@@ -292,6 +292,14 @@ static ssize_t show_state_##_name(struct cpuidle_state *state, \
 	return sprintf(buf, "%s\n", state->_name);\
 }
 
+static ssize_t show_state_default_status(struct cpuidle_state *state,
+					struct cpuidle_state_usage *state_usage,
+					char *buf)
+{
+	return sprintf(buf, "%s\n",
+		state->flags & CPUIDLE_FLAG_OFF ? "disabled" : "enabled");
+}
+
 define_show_state_function(exit_latency)
 define_show_state_function(target_residency)
 define_show_state_function(power_usage)
@@ -310,6 +318,7 @@ define_one_state_ro(power, show_state_power_usage);
 define_one_state_ro(usage, show_state_usage);
 define_one_state_ro(time, show_state_time);
 define_one_state_rw(disable, show_state_disable, store_state_disable);
+define_one_state_ro(default_status, show_state_default_status);
 
 static struct attribute *cpuidle_state_default_attrs[] = {
 	&attr_name.attr,
@@ -320,6 +329,7 @@ static struct attribute *cpuidle_state_default_attrs[] = {
 	&attr_usage.attr,
 	&attr_time.attr,
 	&attr_disable.attr,
+	&attr_default_status.attr,
 	NULL
 };
 

include/linux/cpuidle.h

@@ -29,6 +29,8 @@ struct cpuidle_driver;
  * CPUIDLE DEVICE INTERFACE *
  ****************************/
 
+#define CPUIDLE_STATE_DISABLED_BY_USER         BIT(0)
+
 struct cpuidle_state_usage {
 	unsigned long long	disable;
 	unsigned long long	usage;
@@ -70,6 +72,7 @@ struct cpuidle_state {
 #define CPUIDLE_FLAG_POLLING	BIT(0) /* polling state */
 #define CPUIDLE_FLAG_COUPLED	BIT(1) /* state applies to multiple cpus */
 #define CPUIDLE_FLAG_TIMER_STOP BIT(2) /* timer is stopped on this state */
+#define CPUIDLE_FLAG_OFF       BIT(4) /* disable this state by default */
 
 struct cpuidle_device_kobj;
 struct cpuidle_state_kobj;