powerpc: Show processor cache information in sysfs

Collect cache information from the OF device tree and display it in
the cpu hierarchy in sysfs.  This is intended to be compatible at the
userspace level with x86's implementation[1], hence some of the funny
attribute names.  The arrangement of cache info is not immediately
intuitive, but (again) it's for compatibility's sake.

The cache attributes exposed are:

type (Data, Instruction, or Unified)
level (1, 2, 3...)
size
coherency_line_size
number_of_sets
ways_of_associativity

All of these can be derived on platforms that follow the OF PowerPC
Processor binding.  The code "publishes" only those attributes for
which it is able to determine values; attributes for values which
cannot be determined are not created at all.

[1] arch/x86/kernel/cpu/intel_cacheinfo.c

BenH: Turned some printk's into pr_debug, added better NULL checking
in a couple of places.
Signed-off-by: Nathan Lynch <ntl@pobox.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/kernel/sysfs.c

@@ -22,6 +22,8 @@
 
 static DEFINE_PER_CPU(struct cpu, cpu_devices);
 
+static DEFINE_PER_CPU(struct kobject *, cache_toplevel);
+
 /* SMT stuff */
 
 #ifdef CONFIG_PPC_MULTIPLATFORM
@@ -297,6 +299,287 @@ static struct sysdev_attribute pa6t_attrs[] = {
 #endif /* CONFIG_DEBUG_KERNEL */
 };
 
+struct cache_desc {
+	struct kobject kobj;
+	struct cache_desc *next;
+	const char *type;	/* Instruction, Data, or Unified */
+	u32 size;		/* total cache size in KB */
+	u32 line_size;		/* in bytes */
+	u32 nr_sets;		/* number of sets */
+	u32 level;		/* e.g. 1, 2, 3... */
+	u32 associativity;	/* e.g. 8-way... 0 is fully associative */
+};
+
+DEFINE_PER_CPU(struct cache_desc *, cache_desc);
+
+static struct cache_desc *kobj_to_cache_desc(struct kobject *k)
+{
+	return container_of(k, struct cache_desc, kobj);
+}
+
+static void cache_desc_release(struct kobject *k)
+{
+	struct cache_desc *desc = kobj_to_cache_desc(k);
+
+	pr_debug("%s: releasing %s\n", __func__, kobject_name(k));
+
+	if (desc->next)
+		kobject_put(&desc->next->kobj);
+
+	kfree(kobj_to_cache_desc(k));
+}
+
+static ssize_t cache_desc_show(struct kobject *k, struct attribute *attr, char *buf)
+{
+	struct kobj_attribute *kobj_attr;
+
+	kobj_attr = container_of(attr, struct kobj_attribute, attr);
+
+	return kobj_attr->show(k, kobj_attr, buf);
+}
+
+static struct sysfs_ops cache_desc_sysfs_ops = {
+	.show = cache_desc_show,
+};
+
+static struct kobj_type cache_desc_type = {
+	.release = cache_desc_release,
+	.sysfs_ops = &cache_desc_sysfs_ops,
+};
+
+static ssize_t cache_size_show(struct kobject *k, struct kobj_attribute *attr, char *buf)
+{
+	struct cache_desc *cache = kobj_to_cache_desc(k);
+
+	return sprintf(buf, "%uK\n", cache->size);
+}
+
+static struct kobj_attribute cache_size_attr =
+	__ATTR(size, 0444, cache_size_show, NULL);
+
+static ssize_t cache_line_size_show(struct kobject *k, struct kobj_attribute *attr, char *buf)
+{
+	struct cache_desc *cache = kobj_to_cache_desc(k);
+
+	return sprintf(buf, "%u\n", cache->line_size);
+}
+
+static struct kobj_attribute cache_line_size_attr =
+	__ATTR(coherency_line_size, 0444, cache_line_size_show, NULL);
+
+static ssize_t cache_nr_sets_show(struct kobject *k, struct kobj_attribute *attr, char *buf)
+{
+	struct cache_desc *cache = kobj_to_cache_desc(k);
+
+	return sprintf(buf, "%u\n", cache->nr_sets);
+}
+
+static struct kobj_attribute cache_nr_sets_attr =
+	__ATTR(number_of_sets, 0444, cache_nr_sets_show, NULL);
+
+static ssize_t cache_type_show(struct kobject *k, struct kobj_attribute *attr, char *buf)
+{
+	struct cache_desc *cache = kobj_to_cache_desc(k);
+
+	return sprintf(buf, "%s\n", cache->type);
+}
+
+static struct kobj_attribute cache_type_attr =
+	__ATTR(type, 0444, cache_type_show, NULL);
+
+static ssize_t cache_level_show(struct kobject *k, struct kobj_attribute *attr, char *buf)
+{
+	struct cache_desc *cache = kobj_to_cache_desc(k);
+
+	return sprintf(buf, "%u\n", cache->level);
+}
+
+static struct kobj_attribute cache_level_attr =
+	__ATTR(level, 0444, cache_level_show, NULL);
+
+static ssize_t cache_assoc_show(struct kobject *k, struct kobj_attribute *attr, char *buf)
+{
+	struct cache_desc *cache = kobj_to_cache_desc(k);
+
+	return sprintf(buf, "%u\n", cache->associativity);
+}
+
+static struct kobj_attribute cache_assoc_attr =
+	__ATTR(ways_of_associativity, 0444, cache_assoc_show, NULL);
+
+struct cache_desc_info {
+	const char *type;
+	const char *size_prop;
+	const char *line_size_prop;
+	const char *nr_sets_prop;
+};
+
+/* PowerPC Processor binding says the [di]-cache-* must be equal on
+ * unified caches, so just use d-cache properties. */
+static struct cache_desc_info ucache_info = {
+	.type = "Unified",
+	.size_prop = "d-cache-size",
+	.line_size_prop = "d-cache-line-size",
+	.nr_sets_prop = "d-cache-sets",
+};
+
+static struct cache_desc_info dcache_info = {
+	.type = "Data",
+	.size_prop = "d-cache-size",
+	.line_size_prop = "d-cache-line-size",
+	.nr_sets_prop = "d-cache-sets",
+};
+
+static struct cache_desc_info icache_info = {
+	.type = "Instruction",
+	.size_prop = "i-cache-size",
+	.line_size_prop = "i-cache-line-size",
+	.nr_sets_prop = "i-cache-sets",
+};
+
+static struct cache_desc * __cpuinit create_cache_desc(struct device_node *np, struct kobject *parent, int index, int level, struct cache_desc_info *info)
+{
+	const u32 *cache_line_size;
+	struct cache_desc *new;
+	const u32 *cache_size;
+	const u32 *nr_sets;
+	int rc;
+
+	new = kzalloc(sizeof(*new), GFP_KERNEL);
+	if (!new)
+		return NULL;
+
+	rc = kobject_init_and_add(&new->kobj, &cache_desc_type, parent,
+				  "index%d", index);
+	if (rc)
+		goto err;
+
+	/* type */
+	new->type = info->type;
+	rc = sysfs_create_file(&new->kobj, &cache_type_attr.attr);
+	WARN_ON(rc);
+
+	/* level */
+	new->level = level;
+	rc = sysfs_create_file(&new->kobj, &cache_level_attr.attr);
+	WARN_ON(rc);
+
+	/* size */
+	cache_size = of_get_property(np, info->size_prop, NULL);
+	if (cache_size) {
+		new->size = *cache_size / 1024;
+		rc = sysfs_create_file(&new->kobj,
+				       &cache_size_attr.attr);
+		WARN_ON(rc);
+	}
+
+	/* coherency_line_size */
+	cache_line_size = of_get_property(np, info->line_size_prop, NULL);
+	if (cache_line_size) {
+		new->line_size = *cache_line_size;
+		rc = sysfs_create_file(&new->kobj,
+				       &cache_line_size_attr.attr);
+		WARN_ON(rc);
+	}
+
+	/* number_of_sets */
+	nr_sets = of_get_property(np, info->nr_sets_prop, NULL);
+	if (nr_sets) {
+		new->nr_sets = *nr_sets;
+		rc = sysfs_create_file(&new->kobj,
+				       &cache_nr_sets_attr.attr);
+		WARN_ON(rc);
+	}
+
+	/* ways_of_associativity */
+	if (new->nr_sets == 1) {
+		/* fully associative */
+		new->associativity = 0;
+		goto create_assoc;
+	}
+
+	if (new->nr_sets && new->size && new->line_size) {
+		/* If we have values for all of these we can derive
+		 * the associativity. */
+		new->associativity =
+			((new->size * 1024) / new->nr_sets) / new->line_size;
+create_assoc:
+		rc = sysfs_create_file(&new->kobj,
+				       &cache_assoc_attr.attr);
+		WARN_ON(rc);
+	}
+
+	return new;
+err:
+	kfree(new);
+	return NULL;
+}
+
+static bool cache_is_unified(struct device_node *np)
+{
+	return of_get_property(np, "cache-unified", NULL);
+}
+
+static struct cache_desc * __cpuinit create_cache_index_info(struct device_node *np, struct kobject *parent, int index, int level)
+{
+	const phandle *next_cache_phandle;
+	struct device_node *next_cache;
+	struct cache_desc *new, **end;
+
+	pr_debug("%s(node = %s, index = %d)\n", __func__, np->full_name, index);
+
+	if (cache_is_unified(np)) {
+		new = create_cache_desc(np, parent, index, level,
+					&ucache_info);
+	} else {
+		new = create_cache_desc(np, parent, index, level,
+					&dcache_info);
+		if (new) {
+			index++;
+			new->next = create_cache_desc(np, parent, index, level,
+						      &icache_info);
+		}
+	}
+	if (!new)
+		return NULL;
+
+	end = &new->next;
+	while (*end)
+		end = &(*end)->next;
+
+	next_cache_phandle = of_get_property(np, "l2-cache", NULL);
+	if (!next_cache_phandle)
+		goto out;
+
+	next_cache = of_find_node_by_phandle(*next_cache_phandle);
+	if (!next_cache)
+		goto out;
+
+	*end = create_cache_index_info(next_cache, parent, ++index, ++level);
+
+	of_node_put(next_cache);
+out:
+	return new;
+}
+
+static void __cpuinit create_cache_info(struct sys_device *sysdev)
+{
+	struct kobject *cache_toplevel;
+	struct device_node *np = NULL;
+	int cpu = sysdev->id;
+
+	cache_toplevel = kobject_create_and_add("cache", &sysdev->kobj);
+	if (!cache_toplevel)
+		return;
+	per_cpu(cache_toplevel, cpu) = cache_toplevel;
+	np = of_get_cpu_node(cpu, NULL);
+	if (np != NULL) {
+		per_cpu(cache_desc, cpu) =
+			create_cache_index_info(np, cache_toplevel, 0, 1);
+		of_node_put(np);
+	}
+	return;
+}
 
 static void __cpuinit register_cpu_online(unsigned int cpu)
 {
@@ -346,9 +629,33 @@ static void __cpuinit register_cpu_online(unsigned int cpu)
 
 	if (cpu_has_feature(CPU_FTR_DSCR))
 		sysdev_create_file(s, &attr_dscr);
+
+	create_cache_info(s);
 }
 
 #ifdef CONFIG_HOTPLUG_CPU
+static void remove_cache_info(struct sys_device *sysdev)
+{
+	struct kobject *cache_toplevel;
+	struct cache_desc *cache_desc;
+	int cpu = sysdev->id;
+
+	cache_desc = per_cpu(cache_desc, cpu);
+	if (cache_desc != NULL) {
+		sysfs_remove_file(&cache_desc->kobj, &cache_size_attr.attr);
+		sysfs_remove_file(&cache_desc->kobj, &cache_line_size_attr.attr);
+		sysfs_remove_file(&cache_desc->kobj, &cache_type_attr.attr);
+		sysfs_remove_file(&cache_desc->kobj, &cache_level_attr.attr);
+		sysfs_remove_file(&cache_desc->kobj, &cache_nr_sets_attr.attr);
+		sysfs_remove_file(&cache_desc->kobj, &cache_assoc_attr.attr);
+
+		kobject_put(&cache_desc->kobj);
+	}
+	cache_toplevel = per_cpu(cache_toplevel, cpu);
+	if (cache_toplevel != NULL)
+		kobject_put(cache_toplevel);
+}
+
 static void unregister_cpu_online(unsigned int cpu)
 {
 	struct cpu *c = &per_cpu(cpu_devices, cpu);
@@ -399,6 +706,8 @@ static void unregister_cpu_online(unsigned int cpu)
 
 	if (cpu_has_feature(CPU_FTR_DSCR))
 		sysdev_remove_file(s, &attr_dscr);
+
+	remove_cache_info(s);
 }
 #endif /* CONFIG_HOTPLUG_CPU */