stm class: Introduce framing protocol drivers

At the moment, the stm class applies a certain STP framing pattern to
the data as it is written to the underlying STM device. In order to
allow different framing patterns (aka protocols), this patch introduces
the concept of STP protocol drivers, defines data structures and APIs
for the protocol drivers to use.

Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Tested-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 135 insertions, 10 deletions

diff --git a/drivers/hwtracing/stm/policy.c b/drivers/hwtracing/stm/policy.c
index a505f055f464..8bc90432ae69 100644
--- a/drivers/hwtracing/stm/policy.c
+++ b/drivers/hwtracing/stm/policy.c
@@ -33,8 +33,18 @@ struct stp_policy_node {
 	unsigned int		last_master;
 	unsigned int		first_channel;
 	unsigned int		last_channel;
+	/* this is the one that's exposed to the attributes */
+	unsigned char		priv[0];
 };
 
+void *stp_policy_node_priv(struct stp_policy_node *pn)
+{
+	if (!pn)
+		return NULL;
+
+	return pn->priv;
+}
+
 static struct configfs_subsystem stp_policy_subsys;
 
 void stp_policy_node_get_ranges(struct stp_policy_node *policy_node,
@@ -68,6 +78,14 @@ to_stp_policy_node(struct config_item *item)
 		NULL;
 }
 
+void *to_pdrv_policy_node(struct config_item *item)
+{
+	struct stp_policy_node *node = to_stp_policy_node(item);
+
+	return stp_policy_node_priv(node);
+}
+EXPORT_SYMBOL_GPL(to_pdrv_policy_node);
+
 static ssize_t
 stp_policy_node_masters_show(struct config_item *item, char *page)
 {
@@ -163,7 +181,9 @@ unlock:
 
 static void stp_policy_node_release(struct config_item *item)
 {
-	kfree(to_stp_policy_node(item));
+	struct stp_policy_node *node = to_stp_policy_node(item);
+
+	kfree(node);
 }
 
 static struct configfs_item_operations stp_policy_node_item_ops = {
@@ -182,10 +202,61 @@ static struct configfs_attribute *stp_policy_node_attrs[] = {
 static const struct config_item_type stp_policy_type;
 static const struct config_item_type stp_policy_node_type;
 
+/* lifted from arch/x86/events/core.c */
+static struct configfs_attribute **merge_attr(struct configfs_attribute **a, struct configfs_attribute **b)
+{
+	struct configfs_attribute **new;
+	int j, i;
+
+	for (j = 0; a[j]; j++)
+		;
+	for (i = 0; b[i]; i++)
+		j++;
+	j++;
+
+	new = kmalloc_array(j, sizeof(struct configfs_attribute *),
+			    GFP_KERNEL);
+	if (!new)
+		return NULL;
+
+	j = 0;
+	for (i = 0; a[i]; i++)
+		new[j++] = a[i];
+	for (i = 0; b[i]; i++)
+		new[j++] = b[i];
+	new[j] = NULL;
+
+	return new;
+}
+
+const struct config_item_type *
+get_policy_node_type(struct configfs_attribute **attrs)
+{
+	struct config_item_type *type;
+	struct configfs_attribute **merged;
+
+	type = kmemdup(&stp_policy_node_type, sizeof(stp_policy_node_type),
+		       GFP_KERNEL);
+	if (!type)
+		return NULL;
+
+	merged = merge_attr(stp_policy_node_attrs, attrs);
+	if (!merged) {
+		kfree(type);
+		return NULL;
+	}
+
+	type->ct_attrs = merged;
+
+	return type;
+}
+
 static struct config_group *
 stp_policy_node_make(struct config_group *group, const char *name)
 {
+	const struct config_item_type *type = &stp_policy_node_type;
 	struct stp_policy_node *policy_node, *parent_node;
+	const struct stm_protocol_driver *pdrv;
 	struct stp_policy *policy;
 
 	if (group->cg_item.ci_type == &stp_policy_type) {
@@ -199,12 +270,20 @@ stp_policy_node_make(struct config_group *group, const char *name)
 	if (!policy->stm)
 		return ERR_PTR(-ENODEV);
 
-	policy_node = kzalloc(sizeof(struct stp_policy_node), GFP_KERNEL);
+	pdrv = policy->stm->pdrv;
+	policy_node =
+		kzalloc(offsetof(struct stp_policy_node, priv[pdrv->priv_sz]),
+			GFP_KERNEL);
 	if (!policy_node)
 		return ERR_PTR(-ENOMEM);
 
-	config_group_init_type_name(&policy_node->group, name,
-				    &stp_policy_node_type);
+	if (pdrv->policy_node_init)
+		pdrv->policy_node_init((void *)policy_node->priv);
+
+	if (policy->stm->pdrv_node_type)
+		type = policy->stm->pdrv_node_type;
+
+	config_group_init_type_name(&policy_node->group, name, type);
 
 	policy_node->policy = policy;
 
@@ -254,8 +333,25 @@ static ssize_t stp_policy_device_show(struct config_item *item,
 
 CONFIGFS_ATTR_RO(stp_policy_, device);
 
+static ssize_t stp_policy_protocol_show(struct config_item *item,
+					char *page)
+{
+	struct stp_policy *policy = to_stp_policy(item);
+	ssize_t count;
+
+	count = sprintf(page, "%s\n",
+			(policy && policy->stm) ?
+			policy->stm->pdrv->name :
+			"<none>");
+
+	return count;
+}
+
+CONFIGFS_ATTR_RO(stp_policy_, protocol);
+
 static struct configfs_attribute *stp_policy_attrs[] = {
 	&stp_policy_attr_device,
+	&stp_policy_attr_protocol,
 	NULL,
 };
 
@@ -276,6 +372,7 @@ void stp_policy_unbind(struct stp_policy *policy)
 	stm->policy = NULL;
 	policy->stm = NULL;
 
+	stm_put_protocol(stm->pdrv);
 	stm_put_device(stm);
 }
 
@@ -313,9 +410,12 @@ static const struct config_item_type stp_policy_type = {
 static struct config_group *
 stp_policy_make(struct config_group *group, const char *name)
 {
+	const struct config_item_type *pdrv_node_type;
+	const struct stm_protocol_driver *pdrv;
+	char *devname, *proto, *p;
 	struct config_group *ret;
 	struct stm_device *stm;
-	char *devname, *p;
+	int err;
 
 	devname = kasprintf(GFP_KERNEL, "%s", name);
 	if (!devname)
@@ -326,6 +426,7 @@ stp_policy_make(struct config_group *group, const char *name)
 	 * <device_name> is the name of an existing stm device; may
 	 *               contain dots;
 	 * <policy_name> is an arbitrary string; may not contain dots
+	 * <device_name>:<protocol_name>.<policy_name>
 	 */
 	p = strrchr(devname, '.');
 	if (!p) {
@@ -335,11 +436,29 @@ stp_policy_make(struct config_group *group, const char *name)
 
 	*p = '\0';
 
+	/*
+	 * look for ":<protocol_name>":
+	 *  + no protocol suffix: fall back to whatever is available;
+	 *  + unknown protocol: fail the whole thing
+	 */
+	proto = strrchr(devname, ':');
+	if (proto)
+		*proto++ = '\0';
+
 	stm = stm_find_device(devname);
+	if (!stm) {
+		kfree(devname);
+		return ERR_PTR(-ENODEV);
+	}
+
+	err = stm_lookup_protocol(proto, &pdrv, &pdrv_node_type);
 	kfree(devname);
 
-	if (!stm)
+	/* We don't have any protocol drivers yet */
+	if (err != -ENOENT) {
+		stm_put_device(stm);
 		return ERR_PTR(-ENODEV);
+	}
 
 	mutex_lock(&stm->policy_mutex);
 	if (stm->policy) {
@@ -349,21 +468,27 @@ stp_policy_make(struct config_group *group, const char *name)
 
 	stm->policy = kzalloc(sizeof(*stm->policy), GFP_KERNEL);
 	if (!stm->policy) {
-		ret = ERR_PTR(-ENOMEM);
-		goto unlock_policy;
+		mutex_unlock(&stm->policy_mutex);
+		stm_put_protocol(pdrv);
+		stm_put_device(stm);
+		return ERR_PTR(-ENOMEM);
 	}
 
 	config_group_init_type_name(&stm->policy->group, name,
 				    &stp_policy_type);
-	stm->policy->stm = stm;
 
+	stm->pdrv = pdrv;
+	stm->pdrv_node_type = pdrv_node_type;
+	stm->policy->stm = stm;
 	ret = &stm->policy->group;
 
 unlock_policy:
 	mutex_unlock(&stm->policy_mutex);
 
-	if (IS_ERR(ret))
+	if (IS_ERR(ret)) {
+		stm_put_protocol(stm->pdrv);
 		stm_put_device(stm);
+	}
 
 	return ret;
 }