cpufreq: expose scaling_cur_freq sysfs file for set_policy() drivers

Currently the core does not expose scaling_cur_freq for set_policy()
drivers this breaks some userspace monitoring tools.
Change the core to expose this file for all drivers and if the
set_policy() driver supports the get() callback use it to retrieve the
current frequency.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=73741
Cc: All applicable <stable@vger.kernel.org>
Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/cpufreq/cpufreq.c

@@ -512,7 +512,18 @@ show_one(cpuinfo_max_freq, cpuinfo.max_freq);
 show_one(cpuinfo_transition_latency, cpuinfo.transition_latency);
 show_one(scaling_min_freq, min);
 show_one(scaling_max_freq, max);
-show_one(scaling_cur_freq, cur);
+
+static ssize_t show_scaling_cur_freq(
+	struct cpufreq_policy *policy, char *buf)
+{
+	ssize_t ret;
+
+	if (cpufreq_driver && cpufreq_driver->setpolicy && cpufreq_driver->get)
+		ret = sprintf(buf, "%u\n", cpufreq_driver->get(policy->cpu));
+	else
+		ret = sprintf(buf, "%u\n", policy->cur);
+	return ret;
+}
 
 static int cpufreq_set_policy(struct cpufreq_policy *policy,
 				struct cpufreq_policy *new_policy);
@@ -906,11 +917,11 @@ static int cpufreq_add_dev_interface(struct cpufreq_policy *policy,
 		if (ret)
 			goto err_out_kobj_put;
 	}
-	if (has_target()) {
+
 	ret = sysfs_create_file(&policy->kobj, &scaling_cur_freq.attr);
 	if (ret)
 		goto err_out_kobj_put;
-	}
+
 	if (cpufreq_driver->bios_limit) {
 		ret = sysfs_create_file(&policy->kobj, &bios_limit.attr);
 		if (ret)