Merge tag 'pm+acpi-3.20-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm

Pull ACPI and power management updates from Rafael Wysocki:
 "We have a few new features this time, including a new SFI-based
  cpufreq driver, a new devfreq driver for Tegra Activity Monitor, a new
  devfreq class for providing its governors with raw utilization data
  and a new ACPI driver for AMD SoCs.

  Still, the majority of changes here are reworks of existing code to
  make it more straightforward or to prepare it for implementing new
  features on top of it.  The primary example is the rework of ACPI
  resources handling from Jiang Liu, Thomas Gleixner and Lv Zheng with
  support for IOAPIC hotplug implemented on top of it, but there is
  quite a number of changes of this kind in the cpufreq core, ACPICA,
  ACPI EC driver, ACPI processor driver and the generic power domains
  core code too.

  The most active developer is Viresh Kumar with his cpufreq changes.

  Specifics:

   - Rework of the core ACPI resources parsing code to fix issues in it
     and make using resource offsets more convenient and consolidation
     of some resource-handing code in a couple of places that have grown
     analagous data structures and code to cover the the same gap in the
     core (Jiang Liu, Thomas Gleixner, Lv Zheng).

   - ACPI-based IOAPIC hotplug support on top of the resources handling
     rework (Jiang Liu, Yinghai Lu).

   - ACPICA update to upstream release 20150204 including an interrupt
     handling rework that allows drivers to install raw handlers for
     ACPI GPEs which then become entirely responsible for the given GPE
     and the ACPICA core code won't touch it (Lv Zheng, David E Box,
     Octavian Purdila).

   - ACPI EC driver rework to fix several concurrency issues and other
     problems related to events handling on top of the ACPICA's new
     support for raw GPE handlers (Lv Zheng).

   - New ACPI driver for AMD SoCs analogous to the LPSS (Low-Power
     Subsystem) driver for Intel chips (Ken Xue).

   - Two minor fixes of the ACPI LPSS driver (Heikki Krogerus, Jarkko
     Nikula).

   - Two new blacklist entries for machines (Samsung 730U3E/740U3E and
     510R) where the native backlight interface doesn't work correctly
     while the ACPI one does (Hans de Goede).

   - Rework of the ACPI processor driver's handling of idle states to
     make the code more straightforward and less bloated overall (Rafael
     J Wysocki).

   - Assorted minor fixes related to ACPI and SFI (Andreas Ruprecht,
     Andy Shevchenko, Hanjun Guo, Jan Beulich, Rafael J Wysocki, Yaowei
     Bai).

   - PCI core power management modification to avoid resuming (some)
     runtime-suspended devices during system suspend if they are in the
     right states already (Rafael J Wysocki).

   - New SFI-based cpufreq driver for Intel platforms using SFI
     (Srinidhi Kasagar).

   - cpufreq core fixes, cleanups and simplifications (Viresh Kumar,
     Doug Anderson, Wolfram Sang).

   - SkyLake CPU support and other updates for the intel_pstate driver
     (Kristen Carlson Accardi, Srinivas Pandruvada).

   - cpufreq-dt driver cleanup (Markus Elfring).

   - Init fix for the ARM big.LITTLE cpuidle driver (Sudeep Holla).

   - Generic power domains core code fixes and cleanups (Ulf Hansson).

   - Operating Performance Points (OPP) core code cleanups and kernel
     documentation update (Nishanth Menon).

   - New dabugfs interface to make the list of PM QoS constraints
     available to user space (Nishanth Menon).

   - New devfreq driver for Tegra Activity Monitor (Tomeu Vizoso).

   - New devfreq class (devfreq_event) to provide raw utilization data
     to devfreq governors (Chanwoo Choi).

   - Assorted minor fixes and cleanups related to power management
     (Andreas Ruprecht, Krzysztof Kozlowski, Rickard Strandqvist, Pavel
     Machek, Todd E Brandt, Wonhong Kwon).

   - turbostat updates (Len Brown) and cpupower Makefile improvement
     (Sriram Raghunathan)"

* tag 'pm+acpi-3.20-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (151 commits)
  tools/power turbostat: relax dependency on APERF_MSR
  tools/power turbostat: relax dependency on invariant TSC
  Merge branch 'pci/host-generic' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci into acpi-resources
  tools/power turbostat: decode MSR_*_PERF_LIMIT_REASONS
  tools/power turbostat: relax dependency on root permission
  ACPI / video: Add disable_native_backlight quirk for Samsung 510R
  ACPI / PM: Remove unneeded nested #ifdef
  USB / PM: Remove unneeded #ifdef and associated dead code
  intel_pstate: provide option to only use intel_pstate with HWP
  ACPI / EC: Add GPE reference counting debugging messages
  ACPI / EC: Add query flushing support
  ACPI / EC: Refine command storm prevention support
  ACPI / EC: Add command flushing support.
  ACPI / EC: Introduce STARTED/STOPPED flags to replace BLOCKED flag
  ACPI: add AMD ACPI2Platform device support for x86 system
  ACPI / table: remove duplicate NULL check for the handler of acpi_table_parse()
  ACPI / EC: Update revision due to raw handler mode.
  ACPI / EC: Reduce ec_poll() by referencing the last register access timestamp.
  ACPI / EC: Fix several GPE handling issues by deploying ACPI_GPE_DISPATCH_RAW_HANDLER mode.
  ACPICA: Events: Enable APIs to allow interrupt/polling adaptive request based GPE handling model
  ...

1 files changed, 71 insertions, 103 deletions

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 46bed4f81cde..28e59a48b35f 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -27,9 +27,21 @@
 #include <linux/mutex.h>
 #include <linux/slab.h>
 #include <linux/suspend.h>
+#include <linux/syscore_ops.h>
 #include <linux/tick.h>
 #include <trace/events/power.h>
 
+/* Macros to iterate over lists */
+/* Iterate over online CPUs policies */
+static LIST_HEAD(cpufreq_policy_list);
+#define for_each_policy(__policy)				\
+	list_for_each_entry(__policy, &cpufreq_policy_list, policy_list)
+
+/* Iterate over governors */
+static LIST_HEAD(cpufreq_governor_list);
+#define for_each_governor(__governor)				\
+	list_for_each_entry(__governor, &cpufreq_governor_list, governor_list)
+
 /**
  * The "cpufreq driver" - the arch- or hardware-dependent low
  * level driver of CPUFreq support, and its spinlock. This lock
@@ -40,7 +52,6 @@ static DEFINE_PER_CPU(struct cpufreq_policy *, cpufreq_cpu_data);
 static DEFINE_PER_CPU(struct cpufreq_policy *, cpufreq_cpu_data_fallback);
 static DEFINE_RWLOCK(cpufreq_driver_lock);
 DEFINE_MUTEX(cpufreq_governor_lock);
-static LIST_HEAD(cpufreq_policy_list);
 
 /* This one keeps track of the previously set governor of a removed CPU */
 static DEFINE_PER_CPU(char[CPUFREQ_NAME_LEN], cpufreq_cpu_governor);
@@ -62,7 +73,7 @@ static DECLARE_RWSEM(cpufreq_rwsem);
 /* internal prototypes */
 static int __cpufreq_governor(struct cpufreq_policy *policy,
 		unsigned int event);
-static unsigned int __cpufreq_get(unsigned int cpu);
+static unsigned int __cpufreq_get(struct cpufreq_policy *policy);
 static void handle_update(struct work_struct *work);
 
 /**
@@ -93,7 +104,6 @@ void disable_cpufreq(void)
 {
 	off = 1;
 }
-static LIST_HEAD(cpufreq_governor_list);
 static DEFINE_MUTEX(cpufreq_governor_mutex);
 
 bool have_governor_per_policy(void)
@@ -202,7 +212,7 @@ struct cpufreq_policy *cpufreq_cpu_get(unsigned int cpu)
 	struct cpufreq_policy *policy = NULL;
 	unsigned long flags;
 
-	if (cpufreq_disabled() || (cpu >= nr_cpu_ids))
+	if (cpu >= nr_cpu_ids)
 		return NULL;
 
 	if (!down_read_trylock(&cpufreq_rwsem))
@@ -229,9 +239,6 @@ EXPORT_SYMBOL_GPL(cpufreq_cpu_get);
 
 void cpufreq_cpu_put(struct cpufreq_policy *policy)
 {
-	if (cpufreq_disabled())
-		return;
-
 	kobject_put(&policy->kobj);
 	up_read(&cpufreq_rwsem);
 }
@@ -249,12 +256,12 @@ EXPORT_SYMBOL_GPL(cpufreq_cpu_put);
  * systems as each CPU might be scaled differently. So, use the arch
  * per-CPU loops_per_jiffy value wherever possible.
  */
-#ifndef CONFIG_SMP
-static unsigned long l_p_j_ref;
-static unsigned int l_p_j_ref_freq;
-
 static void adjust_jiffies(unsigned long val, struct cpufreq_freqs *ci)
 {
+#ifndef CONFIG_SMP
+	static unsigned long l_p_j_ref;
+	static unsigned int l_p_j_ref_freq;
+
 	if (ci->flags & CPUFREQ_CONST_LOOPS)
 		return;
 
@@ -270,13 +277,8 @@ static void adjust_jiffies(unsigned long val, struct cpufreq_freqs *ci)
 		pr_debug("scaling loops_per_jiffy to %lu for frequency %u kHz\n",
 			 loops_per_jiffy, ci->new);
 	}
-}
-#else
-static inline void adjust_jiffies(unsigned long val, struct cpufreq_freqs *ci)
-{
-	return;
-}
 #endif
+}
 
 static void __cpufreq_notify_transition(struct cpufreq_policy *policy,
 		struct cpufreq_freqs *freqs, unsigned int state)
@@ -432,11 +434,11 @@ static ssize_t store_boost(struct kobject *kobj, struct attribute *attr,
 }
 define_one_global_rw(boost);
 
-static struct cpufreq_governor *__find_governor(const char *str_governor)
+static struct cpufreq_governor *find_governor(const char *str_governor)
 {
 	struct cpufreq_governor *t;
 
-	list_for_each_entry(t, &cpufreq_governor_list, governor_list)
+	for_each_governor(t)
 		if (!strncasecmp(str_governor, t->name, CPUFREQ_NAME_LEN))
 			return t;
 
@@ -463,12 +465,12 @@ static int cpufreq_parse_governor(char *str_governor, unsigned int *policy,
 			*policy = CPUFREQ_POLICY_POWERSAVE;
 			err = 0;
 		}
-	} else if (has_target()) {
+	} else {
 		struct cpufreq_governor *t;
 
 		mutex_lock(&cpufreq_governor_mutex);
 
-		t = __find_governor(str_governor);
+		t = find_governor(str_governor);
 
 		if (t == NULL) {
 			int ret;
@@ -478,7 +480,7 @@ static int cpufreq_parse_governor(char *str_governor, unsigned int *policy,
 			mutex_lock(&cpufreq_governor_mutex);
 
 			if (ret == 0)
-				t = __find_governor(str_governor);
+				t = find_governor(str_governor);
 		}
 
 		if (t != NULL) {
@@ -513,8 +515,7 @@ show_one(cpuinfo_transition_latency, cpuinfo.transition_latency);
 show_one(scaling_min_freq, min);
 show_one(scaling_max_freq, max);
 
-static ssize_t show_scaling_cur_freq(
-	struct cpufreq_policy *policy, char *buf)
+static ssize_t show_scaling_cur_freq(struct cpufreq_policy *policy, char *buf)
 {
 	ssize_t ret;
 
@@ -563,7 +564,7 @@ store_one(scaling_max_freq, max);
 static ssize_t show_cpuinfo_cur_freq(struct cpufreq_policy *policy,
 					char *buf)
 {
-	unsigned int cur_freq = __cpufreq_get(policy->cpu);
+	unsigned int cur_freq = __cpufreq_get(policy);
 	if (!cur_freq)
 		return sprintf(buf, "<unknown>");
 	return sprintf(buf, "%u\n", cur_freq);
@@ -639,7 +640,7 @@ static ssize_t show_scaling_available_governors(struct cpufreq_policy *policy,
 		goto out;
 	}
 
-	list_for_each_entry(t, &cpufreq_governor_list, governor_list) {
+	for_each_governor(t) {
 		if (i >= (ssize_t) ((PAGE_SIZE / sizeof(char))
 		    - (CPUFREQ_NAME_LEN + 2)))
 			goto out;
@@ -902,7 +903,7 @@ static int cpufreq_add_dev_interface(struct cpufreq_policy *policy,
 
 	/* set up files for this cpu device */
 	drv_attr = cpufreq_driver->attr;
-	while ((drv_attr) && (*drv_attr)) {
+	while (drv_attr && *drv_attr) {
 		ret = sysfs_create_file(&policy->kobj, &((*drv_attr)->attr));
 		if (ret)
 			return ret;
@@ -936,7 +937,7 @@ static void cpufreq_init_policy(struct cpufreq_policy *policy)
 	memcpy(&new_policy, policy, sizeof(*policy));
 
 	/* Update governor of new_policy to the governor used before hotplug */
-	gov = __find_governor(per_cpu(cpufreq_cpu_governor, policy->cpu));
+	gov = find_governor(per_cpu(cpufreq_cpu_governor, policy->cpu));
 	if (gov)
 		pr_debug("Restoring governor %s for cpu %d\n",
 				policy->governor->name, policy->cpu);
@@ -958,7 +959,6 @@ static void cpufreq_init_policy(struct cpufreq_policy *policy)
 	}
 }
 
-#ifdef CONFIG_HOTPLUG_CPU
 static int cpufreq_add_policy_cpu(struct cpufreq_policy *policy,
 				  unsigned int cpu, struct device *dev)
 {
@@ -996,7 +996,6 @@ static int cpufreq_add_policy_cpu(struct cpufreq_policy *policy,
 
 	return sysfs_create_link(&dev->kobj, &policy->kobj, "cpufreq");
 }
-#endif
 
 static struct cpufreq_policy *cpufreq_policy_restore(unsigned int cpu)
 {
@@ -1033,6 +1032,8 @@ static struct cpufreq_policy *cpufreq_policy_alloc(void)
 	init_rwsem(&policy->rwsem);
 	spin_lock_init(&policy->transition_lock);
 	init_waitqueue_head(&policy->transition_wait);
+	init_completion(&policy->kobj_unregister);
+	INIT_WORK(&policy->update, handle_update);
 
 	return policy;
 
@@ -1091,15 +1092,9 @@ static int update_policy_cpu(struct cpufreq_policy *policy, unsigned int cpu,
 	}
 
 	down_write(&policy->rwsem);
-
-	policy->last_cpu = policy->cpu;
 	policy->cpu = cpu;
-
 	up_write(&policy->rwsem);
 
-	blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
-			CPUFREQ_UPDATE_POLICY_CPU, policy);
-
 	return 0;
 }
 
@@ -1110,41 +1105,32 @@ static int __cpufreq_add_dev(struct device *dev, struct subsys_interface *sif)
 	struct cpufreq_policy *policy;
 	unsigned long flags;
 	bool recover_policy = cpufreq_suspended;
-#ifdef CONFIG_HOTPLUG_CPU
-	struct cpufreq_policy *tpolicy;
-#endif
 
 	if (cpu_is_offline(cpu))
 		return 0;
 
 	pr_debug("adding CPU %u\n", cpu);
 
-#ifdef CONFIG_SMP
 	/* check whether a different CPU already registered this
 	 * CPU because it is in the same boat. */
-	policy = cpufreq_cpu_get(cpu);
-	if (unlikely(policy)) {
-		cpufreq_cpu_put(policy);
+	policy = cpufreq_cpu_get_raw(cpu);
+	if (unlikely(policy))
 		return 0;
-	}
-#endif
 
 	if (!down_read_trylock(&cpufreq_rwsem))
 		return 0;
 
-#ifdef CONFIG_HOTPLUG_CPU
 	/* Check if this cpu was hot-unplugged earlier and has siblings */
 	read_lock_irqsave(&cpufreq_driver_lock, flags);
-	list_for_each_entry(tpolicy, &cpufreq_policy_list, policy_list) {
-		if (cpumask_test_cpu(cpu, tpolicy->related_cpus)) {
+	for_each_policy(policy) {
+		if (cpumask_test_cpu(cpu, policy->related_cpus)) {
 			read_unlock_irqrestore(&cpufreq_driver_lock, flags);
-			ret = cpufreq_add_policy_cpu(tpolicy, cpu, dev);
+			ret = cpufreq_add_policy_cpu(policy, cpu, dev);
 			up_read(&cpufreq_rwsem);
 			return ret;
 		}
 	}
 	read_unlock_irqrestore(&cpufreq_driver_lock, flags);
-#endif
 
 	/*
 	 * Restore the saved policy when doing light-weight init and fall back
@@ -1171,9 +1157,6 @@ static int __cpufreq_add_dev(struct device *dev, struct subsys_interface *sif)
 
 	cpumask_copy(policy->cpus, cpumask_of(cpu));
 
-	init_completion(&policy->kobj_unregister);
-	INIT_WORK(&policy->update, handle_update);
-
 	/* call driver. From then on the cpufreq must be able
 	 * to accept all calls to ->verify and ->setpolicy for this CPU
 	 */
@@ -1371,11 +1354,10 @@ static int __cpufreq_remove_dev_prepare(struct device *dev,
 			pr_err("%s: Failed to stop governor\n", __func__);
 			return ret;
 		}
-	}
 
-	if (!cpufreq_driver->setpolicy)
 		strncpy(per_cpu(cpufreq_cpu_governor, cpu),
 			policy->governor->name, CPUFREQ_NAME_LEN);
+	}
 
 	down_read(&policy->rwsem);
 	cpus = cpumask_weight(policy->cpus);
@@ -1416,9 +1398,10 @@ static int __cpufreq_remove_dev_finish(struct device *dev,
 	unsigned long flags;
 	struct cpufreq_policy *policy;
 
-	read_lock_irqsave(&cpufreq_driver_lock, flags);
+	write_lock_irqsave(&cpufreq_driver_lock, flags);
 	policy = per_cpu(cpufreq_cpu_data, cpu);
-	read_unlock_irqrestore(&cpufreq_driver_lock, flags);
+	per_cpu(cpufreq_cpu_data, cpu) = NULL;
+	write_unlock_irqrestore(&cpufreq_driver_lock, flags);
 
 	if (!policy) {
 		pr_debug("%s: No cpu_data found\n", __func__);
@@ -1473,7 +1456,6 @@ static int __cpufreq_remove_dev_finish(struct device *dev,
 		}
 	}
 
-	per_cpu(cpufreq_cpu_data, cpu) = NULL;
 	return 0;
 }
 
@@ -1510,30 +1492,23 @@ static void handle_update(struct work_struct *work)
 /**
  *	cpufreq_out_of_sync - If actual and saved CPU frequency differs, we're
  *	in deep trouble.
- *	@cpu: cpu number
- *	@old_freq: CPU frequency the kernel thinks the CPU runs at
+ *	@policy: policy managing CPUs
  *	@new_freq: CPU frequency the CPU actually runs at
  *
  *	We adjust to current frequency first, and need to clean up later.
  *	So either call to cpufreq_update_policy() or schedule handle_update()).
  */
-static void cpufreq_out_of_sync(unsigned int cpu, unsigned int old_freq,
+static void cpufreq_out_of_sync(struct cpufreq_policy *policy,
 				unsigned int new_freq)
 {
-	struct cpufreq_policy *policy;
 	struct cpufreq_freqs freqs;
-	unsigned long flags;
 
 	pr_debug("Warning: CPU frequency out of sync: cpufreq and timing core thinks of %u, is %u kHz\n",
-		 old_freq, new_freq);
+		 policy->cur, new_freq);
 
-	freqs.old = old_freq;
+	freqs.old = policy->cur;
 	freqs.new = new_freq;
 
-	read_lock_irqsave(&cpufreq_driver_lock, flags);
-	policy = per_cpu(cpufreq_cpu_data, cpu);
-	read_unlock_irqrestore(&cpufreq_driver_lock, flags);
-
 	cpufreq_freq_transition_begin(policy, &freqs);
 	cpufreq_freq_transition_end(policy, &freqs, 0);
 }
@@ -1583,22 +1558,21 @@ unsigned int cpufreq_quick_get_max(unsigned int cpu)
 }
 EXPORT_SYMBOL(cpufreq_quick_get_max);
 
-static unsigned int __cpufreq_get(unsigned int cpu)
+static unsigned int __cpufreq_get(struct cpufreq_policy *policy)
 {
-	struct cpufreq_policy *policy = per_cpu(cpufreq_cpu_data, cpu);
 	unsigned int ret_freq = 0;
 
 	if (!cpufreq_driver->get)
 		return ret_freq;
 
-	ret_freq = cpufreq_driver->get(cpu);
+	ret_freq = cpufreq_driver->get(policy->cpu);
 
 	if (ret_freq && policy->cur &&
 		!(cpufreq_driver->flags & CPUFREQ_CONST_LOOPS)) {
 		/* verify no discrepancy between actual and
 					saved value exists */
 		if (unlikely(ret_freq != policy->cur)) {
-			cpufreq_out_of_sync(cpu, policy->cur, ret_freq);
+			cpufreq_out_of_sync(policy, ret_freq);
 			schedule_work(&policy->update);
 		}
 	}
@@ -1619,7 +1593,7 @@ unsigned int cpufreq_get(unsigned int cpu)
 
 	if (policy) {
 		down_read(&policy->rwsem);
-		ret_freq = __cpufreq_get(cpu);
+		ret_freq = __cpufreq_get(policy);
 		up_read(&policy->rwsem);
 
 		cpufreq_cpu_put(policy);
@@ -1682,7 +1656,7 @@ void cpufreq_suspend(void)
 
 	pr_debug("%s: Suspending Governors\n", __func__);
 
-	list_for_each_entry(policy, &cpufreq_policy_list, policy_list) {
+	for_each_policy(policy) {
 		if (__cpufreq_governor(policy, CPUFREQ_GOV_STOP))
 			pr_err("%s: Failed to stop governor for policy: %p\n",
 				__func__, policy);
@@ -1716,7 +1690,7 @@ void cpufreq_resume(void)
 
 	pr_debug("%s: Resuming Governors\n", __func__);
 
-	list_for_each_entry(policy, &cpufreq_policy_list, policy_list) {
+	for_each_policy(policy) {
 		if (cpufreq_driver->resume && cpufreq_driver->resume(policy))
 			pr_err("%s: Failed to resume driver: %p\n", __func__,
 				policy);
@@ -2006,10 +1980,6 @@ int cpufreq_driver_target(struct cpufreq_policy *policy,
 }
 EXPORT_SYMBOL_GPL(cpufreq_driver_target);
 
-/*
- * when "event" is CPUFREQ_GOV_LIMITS
- */
-
 static int __cpufreq_governor(struct cpufreq_policy *policy,
 					unsigned int event)
 {
@@ -2107,7 +2077,7 @@ int cpufreq_register_governor(struct cpufreq_governor *governor)
 
 	governor->initialized = 0;
 	err = -EBUSY;
-	if (__find_governor(governor->name) == NULL) {
+	if (!find_governor(governor->name)) {
 		err = 0;
 		list_add(&governor->governor_list, &cpufreq_governor_list);
 	}
@@ -2307,8 +2277,7 @@ int cpufreq_update_policy(unsigned int cpu)
 			policy->cur = new_policy.cur;
 		} else {
 			if (policy->cur != new_policy.cur && has_target())
-				cpufreq_out_of_sync(cpu, policy->cur,
-								new_policy.cur);
+				cpufreq_out_of_sync(policy, new_policy.cur);
 		}
 	}
 
@@ -2364,7 +2333,7 @@ static int cpufreq_boost_set_sw(int state)
 	struct cpufreq_policy *policy;
 	int ret = -EINVAL;
 
-	list_for_each_entry(policy, &cpufreq_policy_list, policy_list) {
+	for_each_policy(policy) {
 		freq_table = cpufreq_frequency_get_table(policy->cpu);
 		if (freq_table) {
 			ret = cpufreq_frequency_table_cpuinfo(policy,
@@ -2454,9 +2423,6 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data)
 
 	pr_debug("trying to register driver %s\n", driver_data->name);
 
-	if (driver_data->setpolicy)
-		driver_data->flags |= CPUFREQ_CONST_LOOPS;
-
 	write_lock_irqsave(&cpufreq_driver_lock, flags);
 	if (cpufreq_driver) {
 		write_unlock_irqrestore(&cpufreq_driver_lock, flags);
@@ -2465,6 +2431,9 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data)
 	cpufreq_driver = driver_data;
 	write_unlock_irqrestore(&cpufreq_driver_lock, flags);
 
+	if (driver_data->setpolicy)
+		driver_data->flags |= CPUFREQ_CONST_LOOPS;
+
 	if (cpufreq_boost_supported()) {
 		/*
 		 * Check if driver provides function to enable boost -
@@ -2485,23 +2454,12 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data)
 	if (ret)
 		goto err_boost_unreg;
 
-	if (!(cpufreq_driver->flags & CPUFREQ_STICKY)) {
-		int i;
-		ret = -ENODEV;
-
-		/* check for at least one working CPU */
-		for (i = 0; i < nr_cpu_ids; i++)
-			if (cpu_possible(i) && per_cpu(cpufreq_cpu_data, i)) {
-				ret = 0;
-				break;
-			}
-
+	if (!(cpufreq_driver->flags & CPUFREQ_STICKY) &&
+	    list_empty(&cpufreq_policy_list)) {
 		/* if all ->init() calls failed, unregister */
-		if (ret) {
-			pr_debug("no CPU initialized for driver %s\n",
-				 driver_data->name);
-			goto err_if_unreg;
-		}
+		pr_debug("%s: No CPU initialized for driver %s\n", __func__,
+			 driver_data->name);
+		goto err_if_unreg;
 	}
 
 	register_hotcpu_notifier(&cpufreq_cpu_notifier);
@@ -2556,6 +2514,14 @@ int cpufreq_unregister_driver(struct cpufreq_driver *driver)
 }
 EXPORT_SYMBOL_GPL(cpufreq_unregister_driver);
 
+/*
+ * Stop cpufreq at shutdown to make sure it isn't holding any locks
+ * or mutexes when secondary CPUs are halted.
+ */
+static struct syscore_ops cpufreq_syscore_ops = {
+	.shutdown = cpufreq_suspend,
+};
+
 static int __init cpufreq_core_init(void)
 {
 	if (cpufreq_disabled())
@@ -2564,6 +2530,8 @@ static int __init cpufreq_core_init(void)
 	cpufreq_global_kobject = kobject_create();
 	BUG_ON(!cpufreq_global_kobject);
 
+	register_syscore_ops(&cpufreq_syscore_ops);
+
 	return 0;
 }
 core_initcall(cpufreq_core_init);