Merge branch 'pm-cpufreq'

* pm-cpufreq:
  cpufreq: return EEXIST instead of EBUSY for second registering
  ARM: shmobile: change dev_id to cpu0 while registering cpu clock
  ARM: i.MX: change dev_id to cpu0 while registering cpu clock
  cpufreq: imx6q-cpufreq: assign cpu_dev correctly to cpu0 device
  cpufreq: cpufreq-cpu0: assign cpu_dev correctly to cpu0 device
  cpufreq: unlock correct rwsem while updating policy->cpu
  cpufreq: Clear policy->cpus bits in __cpufreq_remove_dev_finish()

3 files changed, 32 insertions, 13 deletions

diff --git a/drivers/cpufreq/cpufreq-cpu0.c b/drivers/cpufreq/cpufreq-cpu0.c
index cbfffa91ebdd..78c49d8e0f4a 100644
--- a/drivers/cpufreq/cpufreq-cpu0.c
+++ b/drivers/cpufreq/cpufreq-cpu0.c
@@ -12,6 +12,7 @@
 #define pr_fmt(fmt)	KBUILD_MODNAME ": " fmt
 
 #include <linux/clk.h>
+#include <linux/cpu.h>
 #include <linux/cpufreq.h>
 #include <linux/err.h>
 #include <linux/module.h>
@@ -177,7 +178,11 @@ static int cpu0_cpufreq_probe(struct platform_device *pdev)
 	struct device_node *np;
 	int ret;
 
-	cpu_dev = &pdev->dev;
+	cpu_dev = get_cpu_device(0);
+	if (!cpu_dev) {
+		pr_err("failed to get cpu0 device\n");
+		return -ENODEV;
+	}
 
 	np = of_node_get(cpu_dev->of_node);
 	if (!np) {
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 43c24aa756f6..89b3c52cd5c3 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -952,9 +952,20 @@ static void update_policy_cpu(struct cpufreq_policy *policy, unsigned int cpu)
 	if (cpu == policy->cpu)
 		return;
 
+	/*
+	 * Take direct locks as lock_policy_rwsem_write wouldn't work here.
+	 * Also lock for last cpu is enough here as contention will happen only
+	 * after policy->cpu is changed and after it is changed, other threads
+	 * will try to acquire lock for new cpu. And policy is already updated
+	 * by then.
+	 */
+	down_write(&per_cpu(cpu_policy_rwsem, policy->cpu));
+
 	policy->last_cpu = policy->cpu;
 	policy->cpu = cpu;
 
+	up_write(&per_cpu(cpu_policy_rwsem, policy->last_cpu));
+
 #ifdef CONFIG_CPU_FREQ_TABLE
 	cpufreq_frequency_table_update_policy_cpu(policy);
 #endif
@@ -1125,7 +1136,7 @@ static int cpufreq_nominate_new_policy_cpu(struct cpufreq_policy *policy,
 	int ret;
 
 	/* first sibling now owns the new sysfs dir */
-	cpu_dev = get_cpu_device(cpumask_first(policy->cpus));
+	cpu_dev = get_cpu_device(cpumask_any_but(policy->cpus, old_cpu));
 
 	/* Don't touch sysfs files during light-weight tear-down */
 	if (frozen)
@@ -1189,12 +1200,9 @@ static int __cpufreq_remove_dev_prepare(struct device *dev,
 			policy->governor->name, CPUFREQ_NAME_LEN);
 #endif
 
-	WARN_ON(lock_policy_rwsem_write(cpu));
+	lock_policy_rwsem_read(cpu);
 	cpus = cpumask_weight(policy->cpus);
-
-	if (cpus > 1)
-		cpumask_clear_cpu(cpu, policy->cpus);
-	unlock_policy_rwsem_write(cpu);
+	unlock_policy_rwsem_read(cpu);
 
 	if (cpu != policy->cpu) {
 		if (!frozen)
@@ -1203,9 +1211,7 @@ static int __cpufreq_remove_dev_prepare(struct device *dev,
 
 		new_cpu = cpufreq_nominate_new_policy_cpu(policy, cpu, frozen);
 		if (new_cpu >= 0) {
-			WARN_ON(lock_policy_rwsem_write(cpu));
 			update_policy_cpu(policy, new_cpu);
-			unlock_policy_rwsem_write(cpu);
 
 			if (!frozen) {
 				pr_debug("%s: policy Kobject moved to cpu: %d "
@@ -1237,9 +1243,12 @@ static int __cpufreq_remove_dev_finish(struct device *dev,
 		return -EINVAL;
 	}
 
-	lock_policy_rwsem_read(cpu);
+	WARN_ON(lock_policy_rwsem_write(cpu));
 	cpus = cpumask_weight(policy->cpus);
-	unlock_policy_rwsem_read(cpu);
+
+	if (cpus > 1)
+		cpumask_clear_cpu(cpu, policy->cpus);
+	unlock_policy_rwsem_write(cpu);
 
 	/* If cpu is last user of policy, free policy */
 	if (cpus == 1) {
@@ -2095,7 +2104,7 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data)
 	write_lock_irqsave(&cpufreq_driver_lock, flags);
 	if (cpufreq_driver) {
 		write_unlock_irqrestore(&cpufreq_driver_lock, flags);
-		return -EBUSY;
+		return -EEXIST;
 	}
 	cpufreq_driver = driver_data;
 	write_unlock_irqrestore(&cpufreq_driver_lock, flags);
diff --git a/drivers/cpufreq/imx6q-cpufreq.c b/drivers/cpufreq/imx6q-cpufreq.c
index 3e396543aea4..c3fd2a101ca0 100644
--- a/drivers/cpufreq/imx6q-cpufreq.c
+++ b/drivers/cpufreq/imx6q-cpufreq.c
@@ -7,6 +7,7 @@
  */
 
 #include <linux/clk.h>
+#include <linux/cpu.h>
 #include <linux/cpufreq.h>
 #include <linux/delay.h>
 #include <linux/err.h>
@@ -202,7 +203,11 @@ static int imx6q_cpufreq_probe(struct platform_device *pdev)
 	unsigned long min_volt, max_volt;
 	int num, ret;
 
-	cpu_dev = &pdev->dev;
+	cpu_dev = get_cpu_device(0);
+	if (!cpu_dev) {
+		pr_err("failed to get cpu0 device\n");
+		return -ENODEV;
+	}
 
 	np = of_node_get(cpu_dev->of_node);
 	if (!np) {