Revert "msm: cpufreq: Remove cross-calling limitation"

This reverts commit be01a17afb6b6e85456217caa1ac11eb0b6674e1.

Re-introduce cross calling in cpufreq to prevent race conditions in the
hardware when changing PLLs.

A core could be in retention, while another core, could try and set the
frequency of the core in retention, causing a change in PLL and when the
core exits retention, the PLL mismatch could hang the SPM state machine.

Change-Id: I99b454a0f146652f2d8a369f79f6d35748160dcb
Signed-off-by: Praveen Chidambaram <pchidamb@codeaurora.org>

arch/arm/mach-msm/cpufreq.c

@@ -32,6 +32,17 @@
 
 #include "acpuclock.h"
 
+struct cpufreq_work_struct {
+	struct work_struct work;
+	struct cpufreq_policy *policy;
+	struct completion complete;
+	int frequency;
+	int status;
+};
+
+static DEFINE_PER_CPU(struct cpufreq_work_struct, cpufreq_work);
+static struct workqueue_struct *msm_cpufreq_wq;
+
 struct cpufreq_suspend_t {
 	struct mutex suspend_mutex;
 	int device_suspended;
@@ -78,6 +89,15 @@ static int set_cpu_freq(struct cpufreq_policy *policy, unsigned int new_freq)
 	return ret;
 }
 
+static void set_cpu_work(struct work_struct *work)
+{
+	struct cpufreq_work_struct *cpu_work =
+		container_of(work, struct cpufreq_work_struct, work);
+
+	cpu_work->status = set_cpu_freq(cpu_work->policy, cpu_work->frequency);
+	complete(&cpu_work->complete);
+}
+
 static int msm_cpufreq_target(struct cpufreq_policy *policy,
 				unsigned int target_freq,
 				unsigned int relation)
@@ -86,11 +106,17 @@ static int msm_cpufreq_target(struct cpufreq_policy *policy,
 	int index;
 	struct cpufreq_frequency_table *table;
 
+	struct cpufreq_work_struct *cpu_work = NULL;
+	cpumask_var_t mask;
+
 	if (!cpu_active(policy->cpu)) {
 		pr_info("cpufreq: cpu %d is not active.\n", policy->cpu);
 		return -ENODEV;
 	}
 
+	if (!alloc_cpumask_var(&mask, GFP_KERNEL))
+		return -ENOMEM;
+
 	mutex_lock(&per_cpu(cpufreq_suspend, policy->cpu).suspend_mutex);
 
 	if (per_cpu(cpufreq_suspend, policy->cpu).device_suspended) {
@@ -112,9 +138,27 @@ static int msm_cpufreq_target(struct cpufreq_policy *policy,
 		policy->cpu, target_freq, relation,
 		policy->min, policy->max, table[index].frequency);
 
-	ret = set_cpu_freq(policy, table[index].frequency);
+	cpu_work = &per_cpu(cpufreq_work, policy->cpu);
+	cpu_work->policy = policy;
+	cpu_work->frequency = table[index].frequency;
+	cpu_work->status = -ENODEV;
+
+	cpumask_clear(mask);
+	cpumask_set_cpu(policy->cpu, mask);
+	if (cpumask_equal(mask, &current->cpus_allowed)) {
+		ret = set_cpu_freq(cpu_work->policy, cpu_work->frequency);
+		goto done;
+	} else {
+		cancel_work_sync(&cpu_work->work);
+		INIT_COMPLETION(cpu_work->complete);
+		queue_work_on(policy->cpu, msm_cpufreq_wq, &cpu_work->work);
+		wait_for_completion(&cpu_work->complete);
+	}
+
+	ret = cpu_work->status;
 
 done:
+	free_cpumask_var(mask);
 	mutex_unlock(&per_cpu(cpufreq_suspend, policy->cpu).suspend_mutex);
 	return ret;
 }
@@ -197,6 +241,7 @@ static int __cpuinit msm_cpufreq_init(struct cpufreq_policy *policy)
 	int cur_freq;
 	int index;
 	struct cpufreq_frequency_table *table;
+	struct cpufreq_work_struct *cpu_work = NULL;
 
 	table = cpufreq_frequency_get_table(policy->cpu);
 	if (table == NULL)
@@ -225,7 +270,7 @@ static int __cpuinit msm_cpufreq_init(struct cpufreq_policy *policy)
 	    CPUFREQ_RELATION_H, &index) &&
 	    cpufreq_frequency_table_target(policy, table, cur_freq,
 	    CPUFREQ_RELATION_L, &index)) {
-		pr_info("%s: cpu%d at invalid freq: %d\n", __func__,
+		pr_info("cpufreq: cpu%d at invalid freq: %d\n",
 				policy->cpu, cur_freq);
 		return -EINVAL;
 	}
@@ -246,6 +291,10 @@ static int __cpuinit msm_cpufreq_init(struct cpufreq_policy *policy)
 	policy->cpuinfo.transition_latency =
 		acpuclk_get_switch_time() * NSEC_PER_USEC;
 
+	cpu_work = &per_cpu(cpufreq_work, policy->cpu);
+	INIT_WORK(&cpu_work->work, set_cpu_work);
+	init_completion(&cpu_work->complete);
+
 	return 0;
 }
 
@@ -333,6 +382,7 @@ static int __init msm_cpufreq_register(void)
 		per_cpu(cpufreq_suspend, cpu).device_suspended = 0;
 	}
 
+	msm_cpufreq_wq = create_workqueue("msm-cpufreq");
 	register_hotcpu_notifier(&msm_cpufreq_cpu_notifier);
 
 	return cpufreq_register_driver(&msm_cpufreq_driver);