3 files changed, 318 insertions, 18 deletions

diff --git a/drivers/hwtracing/stm/core.c b/drivers/hwtracing/stm/core.c
index 17198e79df3e..915af2541dcd 100644
--- a/drivers/hwtracing/stm/core.c
+++ b/drivers/hwtracing/stm/core.c
@@ -316,11 +316,26 @@ static int stm_output_assign(struct stm_device *stm, unsigned int width,
 	output->master = midx;
 	output->channel = cidx;
 	output->nr_chans = width;
+	if (stm->pdrv->output_open) {
+		void *priv = stp_policy_node_priv(policy_node);
+
+		if (WARN_ON_ONCE(!priv))
+			goto unlock;
+
+		/* configfs subsys mutex is held by the caller */
+		ret = stm->pdrv->output_open(priv, output);
+		if (ret)
+			goto unlock;
+	}
+
 	stm_output_claim(stm, output);
 	dev_dbg(&stm->dev, "assigned %u:%u (+%u)\n", midx, cidx, width);
 
 	ret = 0;
 unlock:
+	if (ret)
+		output->nr_chans = 0;
+
 	spin_unlock(&output->lock);
 	spin_unlock(&stm->mc_lock);
 
@@ -333,6 +348,8 @@ static void stm_output_free(struct stm_device *stm, struct stm_output *output)
 	spin_lock(&output->lock);
 	if (output->nr_chans)
 		stm_output_disclaim(stm, output);
+	if (stm->pdrv && stm->pdrv->output_close)
+		stm->pdrv->output_close(output);
 	spin_unlock(&output->lock);
 	spin_unlock(&stm->mc_lock);
 }
@@ -349,6 +366,127 @@ static int major_match(struct device *dev, const void *data)
 	return MAJOR(dev->devt) == major;
 }
 
+/*
+ * Framing protocol management
+ * Modules can implement STM protocol drivers and (un-)register them
+ * with the STM class framework.
+ */
+static struct list_head stm_pdrv_head;
+static struct mutex stm_pdrv_mutex;
+
+struct stm_pdrv_entry {
+	struct list_head			entry;
+	const struct stm_protocol_driver	*pdrv;
+	const struct config_item_type		*node_type;
+};
+
+static const struct stm_pdrv_entry *
+__stm_lookup_protocol(const char *name)
+{
+	struct stm_pdrv_entry *pe;
+
+	/*
+	 * If no name is given (NULL or ""), fall back to "p_basic".
+	 */
+	if (!name || !*name)
+		name = "p_basic";
+
+	list_for_each_entry(pe, &stm_pdrv_head, entry) {
+		if (!strcmp(name, pe->pdrv->name))
+			return pe;
+	}
+
+	return NULL;
+}
+
+int stm_register_protocol(const struct stm_protocol_driver *pdrv)
+{
+	struct stm_pdrv_entry *pe = NULL;
+	int ret = -ENOMEM;
+
+	mutex_lock(&stm_pdrv_mutex);
+
+	if (__stm_lookup_protocol(pdrv->name)) {
+		ret = -EEXIST;
+		goto unlock;
+	}
+
+	pe = kzalloc(sizeof(*pe), GFP_KERNEL);
+	if (!pe)
+		goto unlock;
+
+	if (pdrv->policy_attr) {
+		pe->node_type = get_policy_node_type(pdrv->policy_attr);
+		if (!pe->node_type)
+			goto unlock;
+	}
+
+	list_add_tail(&pe->entry, &stm_pdrv_head);
+	pe->pdrv = pdrv;
+
+	ret = 0;
+unlock:
+	mutex_unlock(&stm_pdrv_mutex);
+
+	if (ret)
+		kfree(pe);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(stm_register_protocol);
+
+void stm_unregister_protocol(const struct stm_protocol_driver *pdrv)
+{
+	struct stm_pdrv_entry *pe, *iter;
+
+	mutex_lock(&stm_pdrv_mutex);
+
+	list_for_each_entry_safe(pe, iter, &stm_pdrv_head, entry) {
+		if (pe->pdrv == pdrv) {
+			list_del(&pe->entry);
+
+			if (pe->node_type) {
+				kfree(pe->node_type->ct_attrs);
+				kfree(pe->node_type);
+			}
+			kfree(pe);
+			break;
+		}
+	}
+
+	mutex_unlock(&stm_pdrv_mutex);
+}
+EXPORT_SYMBOL_GPL(stm_unregister_protocol);
+
+static bool stm_get_protocol(const struct stm_protocol_driver *pdrv)
+{
+	return try_module_get(pdrv->owner);
+}
+
+void stm_put_protocol(const struct stm_protocol_driver *pdrv)
+{
+	module_put(pdrv->owner);
+}
+
+int stm_lookup_protocol(const char *name,
+			const struct stm_protocol_driver **pdrv,
+			const struct config_item_type **node_type)
+{
+	const struct stm_pdrv_entry *pe;
+
+	mutex_lock(&stm_pdrv_mutex);
+
+	pe = __stm_lookup_protocol(name);
+	if (pe && pe->pdrv && stm_get_protocol(pe->pdrv)) {
+		*pdrv = pe->pdrv;
+		*node_type = pe->node_type;
+	}
+
+	mutex_unlock(&stm_pdrv_mutex);
+
+	return pe ? 0 : -ENOENT;
+}
+
 static int stm_char_open(struct inode *inode, struct file *file)
 {
 	struct stm_file *stmf;
@@ -1176,6 +1314,8 @@ static int __init stm_core_init(void)
 		goto err_src;
 
 	init_srcu_struct(&stm_source_srcu);
+	INIT_LIST_HEAD(&stm_pdrv_head);
+	mutex_init(&stm_pdrv_mutex);
 
 	stm_core_up++;
 
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;
 }
diff --git a/drivers/hwtracing/stm/stm.h b/drivers/hwtracing/stm/stm.h
index e5df08ae59cf..ed7f3d07fa47 100644
--- a/drivers/hwtracing/stm/stm.h
+++ b/drivers/hwtracing/stm/stm.h
@@ -10,20 +10,17 @@
 #ifndef _STM_STM_H_
 #define _STM_STM_H_
 
+#include <linux/configfs.h>
+
 struct stp_policy;
 struct stp_policy_node;
+struct stm_protocol_driver;
 
-struct stp_policy_node *
-stp_policy_node_lookup(struct stm_device *stm, char *s);
-void stp_policy_node_put(struct stp_policy_node *policy_node);
-void stp_policy_unbind(struct stp_policy *policy);
-
-void stp_policy_node_get_ranges(struct stp_policy_node *policy_node,
-				unsigned int *mstart, unsigned int *mend,
-				unsigned int *cstart, unsigned int *cend);
 int stp_configfs_init(void);
 void stp_configfs_exit(void);
 
+void *stp_policy_node_priv(struct stp_policy_node *pn);
+
 struct stp_master {
 	unsigned int	nr_free;
 	unsigned long	chan_map[0];
@@ -40,6 +37,9 @@ struct stm_device {
 	struct mutex		link_mutex;
 	spinlock_t		link_lock;
 	struct list_head	link_list;
+	/* framing protocol in use */
+	const struct stm_protocol_driver	*pdrv;
+	const struct config_item_type		*pdrv_node_type;
 	/* master allocation */
 	spinlock_t		mc_lock;
 	struct stp_master	*masters[0];
@@ -48,11 +48,24 @@ struct stm_device {
 #define to_stm_device(_d)				\
 	container_of((_d), struct stm_device, dev)
 
+struct stp_policy_node *
+stp_policy_node_lookup(struct stm_device *stm, char *s);
+void stp_policy_node_put(struct stp_policy_node *policy_node);
+void stp_policy_unbind(struct stp_policy *policy);
+
+void stp_policy_node_get_ranges(struct stp_policy_node *policy_node,
+				unsigned int *mstart, unsigned int *mend,
+				unsigned int *cstart, unsigned int *cend);
+
+const struct config_item_type *
+get_policy_node_type(struct configfs_attribute **attrs);
+
 struct stm_output {
 	spinlock_t		lock;
 	unsigned int		master;
 	unsigned int		channel;
 	unsigned int		nr_chans;
+	void			*pdrv_private;
 };
 
 struct stm_file {
@@ -76,4 +89,26 @@ struct stm_source_device {
 #define to_stm_source_device(_d)				\
 	container_of((_d), struct stm_source_device, dev)
 
+void *to_pdrv_policy_node(struct config_item *item);
+
+struct stm_protocol_driver {
+	struct module	*owner;
+	const char	*name;
+	ssize_t		(*write)(struct stm_data *data,
+				 struct stm_output *output, unsigned int chan,
+				 const char *buf, size_t count);
+	void		(*policy_node_init)(void *arg);
+	int		(*output_open)(void *priv, struct stm_output *output);
+	void		(*output_close)(struct stm_output *output);
+	ssize_t		priv_sz;
+	struct configfs_attribute	**policy_attr;
+};
+
+int stm_register_protocol(const struct stm_protocol_driver *pdrv);
+void stm_unregister_protocol(const struct stm_protocol_driver *pdrv);
+int stm_lookup_protocol(const char *name,
+			const struct stm_protocol_driver **pdrv,
+			const struct config_item_type **type);
+void stm_put_protocol(const struct stm_protocol_driver *pdrv);
+
 #endif /* _STM_STM_H_ */