cpufreq: drivers with target_index() must set freq_table

Since the cpufreq core directly uses freq_table, for cpufreq drivers
that set their target_index() callback, make it mandatory for them to
set the same.

Since this is set per policy and normally from policy->init(), do this
from cpufreq_table_validate_and_sort() which gets called right after
->init().

Reported-by: Yajun Deng <yajun.deng@linux.dev>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Author: vireshk

drivers/cpufreq/cpufreq.c

@@ -73,6 +73,11 @@ static inline bool has_target(void)
 	return cpufreq_driver->target_index || cpufreq_driver->target;
 }
 
+bool has_target_index(void)
+{
+	return !!cpufreq_driver->target_index;
+}
+
 /* internal prototypes */
 static unsigned int __cpufreq_get(struct cpufreq_policy *policy);
 static int cpufreq_init_governor(struct cpufreq_policy *policy);

drivers/cpufreq/freq_table.c

@@ -355,8 +355,13 @@ int cpufreq_table_validate_and_sort(struct cpufreq_policy *policy)
 {
 	int ret;
 
-	if (!policy->freq_table)
+	if (!policy->freq_table) {
+		/* Freq table must be passed by drivers with target_index() */
+		if (has_target_index())
+			return -EINVAL;
+
 		return 0;
+	}
 
 	ret = cpufreq_frequency_table_cpuinfo(policy, policy->freq_table);
 	if (ret)

include/linux/cpufreq.h

@@ -237,6 +237,7 @@ bool cpufreq_supports_freq_invariance(void);
 struct kobject *get_governor_parent_kobj(struct cpufreq_policy *policy);
 void cpufreq_enable_fast_switch(struct cpufreq_policy *policy);
 void cpufreq_disable_fast_switch(struct cpufreq_policy *policy);
+bool has_target_index(void);
 #else
 static inline unsigned int cpufreq_get(unsigned int cpu)
 {