[CPUFREQ] allow cpufreq drivers to export sysfs files

This patch lets cpufreq drivers export per-CPU files in the cpufreq and
cpu-specific sysfs directory. As an example, a file
"scaling_available_frequencies" is added to the p4-clockmod.c driver.

arch/i386/kernel/cpu/cpufreq/p4-clockmod.c

@@ -214,6 +214,7 @@ static int cpufreq_p4_cpu_init(struct cpufreq_policy *policy)
 		else
 			p4clockmod_table[i].frequency = (stock_freq * i)/8;
 	}
+	cpufreq_frequency_table_get_attr(p4clockmod_table, policy->cpu);
 	
 	/* cpuinfo and default policy values */
 	policy->policy = CPUFREQ_POLICY_PERFORMANCE;
@@ -226,9 +227,14 @@ static int cpufreq_p4_cpu_init(struct cpufreq_policy *policy)
 
 static int cpufreq_p4_cpu_exit(struct cpufreq_policy *policy)
 {
+	cpufreq_frequency_table_put_attr(policy->cpu);    
 	return cpufreq_p4_setdc(policy->cpu, DC_DISABLE);
 }
 
+static struct freq_attr* p4clockmod_attr[] = {
+	&cpufreq_freq_attr_scaling_available_freqs,
+	NULL,
+};
 
 static struct cpufreq_driver p4clockmod_driver = {
 	.verify 	= cpufreq_p4_verify,
@@ -237,6 +243,7 @@ static struct cpufreq_driver p4clockmod_driver = {
 	.exit		= cpufreq_p4_cpu_exit,
 	.name		= "p4-clockmod",
 	.owner		= THIS_MODULE,
+	.attr		= p4clockmod_attr,
 };
 
 

drivers/cpufreq/freq_table.c

@@ -147,6 +147,56 @@ int cpufreq_frequency_table_target(struct cpufreq_policy *policy,
 }
 EXPORT_SYMBOL_GPL(cpufreq_frequency_table_target);
 
+static struct cpufreq_frequency_table *show_table[NR_CPUS];
+/**
+ * show_scaling_governor - show the current policy for the specified CPU
+ */
+static ssize_t show_available_freqs (struct cpufreq_policy *policy, char *buf)
+{
+	unsigned int i = 0;
+	unsigned int cpu = policy->cpu;
+	ssize_t count = 0;
+	struct cpufreq_frequency_table *table;
+
+	if (!show_table[cpu])
+		return -ENODEV;
+
+	table = show_table[cpu];
+
+	for (i=0; (table[i].frequency != CPUFREQ_TABLE_END); i++) {
+		if (table[i].frequency == CPUFREQ_ENTRY_INVALID)
+			continue;
+		count += sprintf(&buf[count], "%d ", table[i].frequency);
+	}
+	count += sprintf(&buf[count], "\n");
+
+	return count;
+
+}
+
+struct freq_attr cpufreq_freq_attr_scaling_available_freqs = {
+	.attr = { .name = "scaling_available_frequencies", .mode = 0444 },
+	.show = show_available_freqs,
+};
+EXPORT_SYMBOL_GPL(cpufreq_freq_attr_scaling_available_freqs);
+
+/*
+ * if you use these, you must assure that the frequency table is valid
+ * all the time between get_attr and put_attr!
+ */
+void cpufreq_frequency_table_get_attr(struct cpufreq_frequency_table *table, 
+				      unsigned int cpu)
+{
+	show_table[cpu] = table;
+}
+EXPORT_SYMBOL_GPL(cpufreq_frequency_table_get_attr);
+
+void cpufreq_frequency_table_put_attr(unsigned int cpu)
+{
+	show_table[cpu] = NULL;
+}
+EXPORT_SYMBOL_GPL(cpufreq_frequency_table_put_attr);
+
 
 MODULE_AUTHOR ("Dominik Brodowski <linux@brodo.de>");
 MODULE_DESCRIPTION ("CPUfreq frequency table helpers");

include/linux/cpufreq.h

@@ -152,6 +152,8 @@ void cpufreq_unregister_governor(struct cpufreq_governor *governor);
 #define CPUFREQ_RELATION_L 0  /* lowest frequency at or above target */
 #define CPUFREQ_RELATION_H 1  /* highest frequency below or at target */
 
+struct freq_attr;
+
 struct cpufreq_driver {
 	/* needed by all drivers */
 	int	(*verify)	(struct cpufreq_policy *policy);
@@ -166,6 +168,7 @@ struct cpufreq_driver {
 	/* optional, for the moment */
 	int	(*init)		(struct cpufreq_policy *policy);
 	int	(*exit)		(struct cpufreq_policy *policy);
+	struct freq_attr	**attr;
 };
 
 int cpufreq_register_driver(struct cpufreq_driver *driver_data);
@@ -298,6 +301,15 @@ int cpufreq_frequency_table_target(struct cpufreq_policy *policy,
 				   unsigned int relation,
 				   unsigned int *index);
 
+/* the following are really really optional */
+extern struct freq_attr cpufreq_freq_attr_scaling_available_freqs;
+
+void cpufreq_frequency_table_get_attr(struct cpufreq_frequency_table *table, 
+				      unsigned int cpu);
+
+void cpufreq_frequency_table_put_attr(unsigned int cpu);
+
+
 #endif /* CONFIG_CPU_FREQ_TABLE */
 
 #endif /* _LINUX_CPUFREQ_H */

kernel/cpufreq.c

@@ -340,6 +340,7 @@ static int cpufreq_add_dev (struct device * dev)
 	int ret = 0;
 	struct cpufreq_policy new_policy;
 	struct cpufreq_policy *policy;
+	struct freq_attr **drv_attr;
 
 	if (!kset_get(&cpufreq_interface.kset))
 		return -EINVAL;
@@ -379,6 +380,12 @@ static int cpufreq_add_dev (struct device * dev)
 	if (ret)
 		goto out;
 
+	drv_attr = cpufreq_driver->attr;
+	while ((drv_attr) && (*drv_attr)) {
+		sysfs_create_file(&policy->kobj, &((*drv_attr)->attr));
+		drv_attr++;
+	}
+
 	/* set default policy */
 	ret = cpufreq_set_policy(&new_policy);
 	if (ret)