[PATCH v2 1/2] cpufreq_stats: Adds sysfs file /sys/devices/system/cpu/cpufreq/current_in_state

[Ruchi Kandoi <kandoiruchi@google.com>]

Adds the sysfs file for userspace to initialize the active current
values for all the cores at each of the frequencies.

The format for storing the values is as follows:
echo "CPU<cpu#>:<freq1>=<current in uA> <freq2>=<current>,CPU<cpu#>:
..." > /sys/devices/system/cpu/cpufreq/current_in_state

Signed-off-by: Ruchi Kandoi <kandoiruchi@google.com>
---
 drivers/cpufreq/cpufreq_stats.c | 163 +++++++++++++++++++++++++++++++++++++++-
 1 file changed, 161 insertions(+), 2 deletions(-)

diff --git a/drivers/cpufreq/cpufreq_stats.c b/drivers/cpufreq/cpufreq_stats.c
index 5e370a3..6f0b562 100644
--- a/drivers/cpufreq/cpufreq_stats.c
+++ b/drivers/cpufreq/cpufreq_stats.c
@@ -30,6 +30,14 @@ struct cpufreq_stats {
 #endif
 };
 
+struct cpufreq_power_stats {
+	unsigned int state_num;
+	unsigned int *curr;
+	unsigned int *freq_table;
+};
+
+static DEFINE_PER_CPU(struct cpufreq_power_stats *, cpufreq_power_stats);
+
 static int cpufreq_stats_update(struct cpufreq_stats *stats)
 {
 	unsigned long long cur_time = get_jiffies_64();
@@ -61,6 +69,87 @@ static ssize_t show_time_in_state(struct cpufreq_policy *policy, char *buf)
 	return len;
 }
 
+static void store_current_value(struct cpufreq_power_stats *powerstats,
+		int freq, int curr)
+{
+	int i;
+
+	/* freq_table doesn't contain any CPU_FREQ_INVALID */
+	for (i = 0; i < powerstats->state_num; i++) {
+		if (powerstats->freq_table[i] == freq) {
+			powerstats->curr[i] = curr;
+			break;
+		}
+	}
+}
+
+static ssize_t store_current_in_state(struct cpufreq_policy *policy,
+		const char *buf, size_t len)
+{
+	char *cp, *cp2, *start, *buffer;
+	unsigned int cpu_num, ret, curr, freq;
+	struct cpufreq_power_stats *powerstats;
+
+	if (!buf || len < 0)
+		return len;
+
+	buffer = kzalloc(len + 1, GFP_KERNEL);
+	if (!buffer)
+		return len;
+
+	strncpy(buffer, buf, len);
+	buffer[len] = '\0';
+	cp = buffer;
+	spin_lock(&cpufreq_stats_lock);
+	while ((start = strsep(&cp, ","))) {
+		ret = sscanf(start, "CPU%u:", &cpu_num);
+		if (ret != 1 || cpu_num > (num_possible_cpus() - 1)) {
+			ret = -EINVAL;
+			goto error;
+		}
+		powerstats = per_cpu(cpufreq_power_stats, cpu_num);
+		if (!powerstats)
+			continue;
+
+		/* sscanf makes sure that strchr doesn't return a NULL */
+		cp2 = strchr(start, ':') + 1;
+		while ((start = strsep(&cp2, " "))) {
+			if (sscanf(start, "%u=%u", &freq, &curr) != 2) {
+				ret = -EINVAL;
+				goto error;
+			}
+			store_current_value(powerstats, freq, curr);
+		}
+	}
+	ret = len;
+error:
+	spin_unlock(&cpufreq_stats_lock);
+	kfree(buffer);
+	return ret;
+}
+
+static ssize_t show_current_in_state(struct cpufreq_policy *policy, char *buf)
+{
+	ssize_t len = 0;
+	unsigned int i, cpu;
+	struct cpufreq_power_stats *powerstats;
+
+	spin_lock(&cpufreq_stats_lock);
+	for_each_possible_cpu(cpu) {
+		powerstats = per_cpu(cpufreq_power_stats, cpu);
+		if (!powerstats)
+			continue;
+		len += scnprintf(buf + len, PAGE_SIZE - len, "CPU%d:", cpu);
+		for (i = 0; i < powerstats->state_num; i++)
+			len += scnprintf(buf + len, PAGE_SIZE - len,
+					"%d=%d ", powerstats->freq_table[i],
+					powerstats->curr[i]);
+		len += scnprintf(buf + len, PAGE_SIZE - len, "\n");
+	}
+	spin_unlock(&cpufreq_stats_lock);
+	return len;
+}
+
 #ifdef CONFIG_CPU_FREQ_STAT_DETAILS
 static ssize_t show_trans_table(struct cpufreq_policy *policy, char *buf)
 {
@@ -107,6 +196,7 @@ cpufreq_freq_attr_ro(trans_table);
 
 cpufreq_freq_attr_ro(total_trans);
 cpufreq_freq_attr_ro(time_in_state);
+cpufreq_freq_attr_rw(current_in_state);
 
 static struct attribute *default_attrs[] = {
 	&total_trans.attr,
@@ -159,6 +249,67 @@ static void cpufreq_stats_free_table(unsigned int cpu)
 	cpufreq_cpu_put(policy);
 }
 
+static void cpufreq_powerstats_free(void)
+{
+	int cpu;
+	struct cpufreq_power_stats *powerstats;
+
+	sysfs_remove_file(cpufreq_global_kobject, &current_in_state.attr);
+
+	for_each_possible_cpu(cpu) {
+		powerstats = per_cpu(cpufreq_power_stats, cpu);
+		if (!powerstats)
+			continue;
+		kfree(powerstats->curr);
+		kfree(powerstats);
+		per_cpu(cpufreq_power_stats, cpu) = NULL;
+	}
+}
+
+static void cpufreq_powerstats_create(unsigned int cpu)
+{
+	unsigned int alloc_size, i = 0, j = 0, count = 0;
+	struct cpufreq_power_stats *powerstats;
+	struct cpufreq_frequency_table *pos, *table;
+
+	/* We need cpufreq table for creating power stats table */
+	table = cpufreq_frequency_get_table(cpu);
+	if (unlikely(!table))
+		return;
+
+	powerstats = kzalloc(sizeof(struct cpufreq_power_stats),
+			GFP_KERNEL);
+	if (!powerstats)
+		return;
+
+	/* Find total allocation size */
+	cpufreq_for_each_valid_entry(pos, table)
+		count++;
+
+	/* Allocate memory for freq table per cpu as well as clockticks per
+	 * freq*/
+	alloc_size = count * sizeof(unsigned int) +
+		count * sizeof(unsigned int);
+	powerstats->curr = kzalloc(alloc_size, GFP_KERNEL);
+	if (!powerstats->curr) {
+		kfree(powerstats);
+		return;
+	}
+	powerstats->freq_table = powerstats->curr + count;
+
+	spin_lock(&cpufreq_stats_lock);
+	for (i = 0; table[i].frequency != CPUFREQ_TABLE_END && j < count; i++) {
+		unsigned int freq = table[i].frequency;
+
+		if (freq == CPUFREQ_ENTRY_INVALID)
+			continue;
+		powerstats->freq_table[j++] = freq;
+	}
+	powerstats->state_num = j;
+	per_cpu(cpufreq_power_stats, cpu) = powerstats;
+	spin_unlock(&cpufreq_stats_lock);
+}
+
 static int __cpufreq_stats_create_table(struct cpufreq_policy *policy)
 {
 	unsigned int i = 0, count = 0, ret = -ENOMEM;
@@ -249,9 +400,11 @@ static int cpufreq_stat_notifier_policy(struct notifier_block *nb,
 	int ret = 0;
 	struct cpufreq_policy *policy = data;
 
-	if (val == CPUFREQ_CREATE_POLICY)
+	if (val == CPUFREQ_CREATE_POLICY) {
 		ret = __cpufreq_stats_create_table(policy);
-	else if (val == CPUFREQ_REMOVE_POLICY)
+		if (!per_cpu(cpufreq_power_stats, policy->cpu))
+			cpufreq_powerstats_create(policy->cpu);
+	} else if (val == CPUFREQ_REMOVE_POLICY)
 		__cpufreq_stats_free_table(policy);
 
 	return ret;
@@ -335,8 +488,13 @@ static int __init cpufreq_stats_init(void)
 		return ret;
 	}
 
+	ret = sysfs_create_file(cpufreq_global_kobject, &current_in_state.attr);
+	if (ret)
+		pr_warn("Cannot create sysfs file for cpufreq current stats\n");
+
 	return 0;
 }
+
 static void __exit cpufreq_stats_exit(void)
 {
 	unsigned int cpu;
@@ -347,6 +505,7 @@ static void __exit cpufreq_stats_exit(void)
 			CPUFREQ_TRANSITION_NOTIFIER);
 	for_each_online_cpu(cpu)
 		cpufreq_stats_free_table(cpu);
+	cpufreq_powerstats_free();
 }
 
 MODULE_AUTHOR("Zou Nan hai <nanhai.zou@intel.com>");
-- 
2.2.0.rc0.207.ga3a616c