[PATCH RFC v2 1/3] drm/dp: Keep a list of drm_dp_aux helper.

[Rafael Antognolli <rafael.antognolli@xxxxxxxxx>]

This list will be used to get the aux channels registered through the
helpers. One function is provided to set a callback for added/removed
aux channels, and another function to iterate over the list of aux
channels.

Signed-off-by: Rafael Antognolli <rafael.antognolli@xxxxxxxxx>
---
 drivers/gpu/drm/drm_dp_helper.c | 73 +++++++++++++++++++++++++++++++++++++++++
 include/drm/drm_dp_helper.h     |  5 +++
 2 files changed, 78 insertions(+)

diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
index 9535c5b..41bdd93 100644
--- a/drivers/gpu/drm/drm_dp_helper.c
+++ b/drivers/gpu/drm/drm_dp_helper.c
@@ -746,6 +746,56 @@ static const struct i2c_algorithm drm_dp_i2c_algo = {
 	.master_xfer = drm_dp_i2c_xfer,
 };
 
+struct drm_dp_aux_node {
+	struct klist_node list;
+	struct drm_dp_aux *aux;
+};
+
+static DEFINE_KLIST(drm_dp_aux_list, NULL, NULL);
+
+static int (*aux_dev_cb)(int action, struct drm_dp_aux *aux) = NULL;
+
+void drm_dp_aux_set_aux_dev(int (*fn)(int, struct drm_dp_aux *))
+{
+	aux_dev_cb = fn;
+}
+EXPORT_SYMBOL(drm_dp_aux_set_aux_dev);
+
+static struct drm_dp_aux *next_aux(struct klist_iter *i)
+{
+	struct klist_node *n = klist_next(i);
+	struct drm_dp_aux *aux = NULL;
+	struct drm_dp_aux_node *aux_node;
+
+	if (n) {
+		aux_node = container_of(n, struct drm_dp_aux_node, list);
+		aux = aux_node->aux;
+	}
+	return aux;
+}
+
+int drm_dp_aux_for_each(void *data, int (*fn)(struct drm_dp_aux *, void *))
+{
+	struct klist_iter i;
+	struct drm_dp_aux *aux;
+	int error = 0;
+
+	klist_iter_init(&drm_dp_aux_list, &i);
+	while ((aux = next_aux(&i)) && !error)
+		error = fn(aux, data);
+	klist_iter_exit(&i);
+	return error;
+}
+EXPORT_SYMBOL(drm_dp_aux_for_each);
+
+static int drm_dp_aux_dev_inform(int action, struct drm_dp_aux *aux)
+{
+	if (aux_dev_cb) {
+		return aux_dev_cb(action, aux);
+	}
+	return 0;
+}
+
 /**
  * drm_dp_aux_register() - initialise and register aux channel
  * @aux: DisplayPort AUX channel
@@ -754,6 +804,7 @@ static const struct i2c_algorithm drm_dp_i2c_algo = {
  */
 int drm_dp_aux_register(struct drm_dp_aux *aux)
 {
+	struct drm_dp_aux_node *aux_node;
 	mutex_init(&aux->hw_mutex);
 
 	aux->ddc.algo = &drm_dp_i2c_algo;
@@ -768,6 +819,14 @@ int drm_dp_aux_register(struct drm_dp_aux *aux)
 	strlcpy(aux->ddc.name, aux->name ? aux->name : dev_name(aux->dev),
 		sizeof(aux->ddc.name));
 
+	/* add aux to list and notify listeners */
+	aux_node = kzalloc(sizeof(*aux_node), GFP_KERNEL);
+	if (!aux_node)
+		return -ENOMEM;
+	aux_node->aux = aux;
+	klist_add_tail(&aux_node->list, &drm_dp_aux_list);
+	drm_dp_aux_dev_inform(DRM_DP_ADD_AUX, aux);
+
 	return i2c_add_adapter(&aux->ddc);
 }
 EXPORT_SYMBOL(drm_dp_aux_register);
@@ -778,6 +837,20 @@ EXPORT_SYMBOL(drm_dp_aux_register);
  */
 void drm_dp_aux_unregister(struct drm_dp_aux *aux)
 {
+	struct klist_iter i;
+	struct klist_node *n;
+
+	klist_iter_init(&drm_dp_aux_list, &i);
+	while ((n = klist_next(&i))) {
+		struct drm_dp_aux_node *aux_node =
+			container_of(n, struct drm_dp_aux_node, list);
+		if (aux_node->aux == aux) {
+			klist_del(n);
+			kfree(aux_node);
+			break;
+		}
+	}
+	drm_dp_aux_dev_inform(DRM_DP_DEL_AUX, aux);
 	i2c_del_adapter(&aux->ddc);
 }
 EXPORT_SYMBOL(drm_dp_aux_unregister);
diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
index 9ec4716..f92de26 100644
--- a/include/drm/drm_dp_helper.h
+++ b/include/drm/drm_dp_helper.h
@@ -763,7 +763,12 @@ int drm_dp_link_power_up(struct drm_dp_aux *aux, struct drm_dp_link *link);
 int drm_dp_link_power_down(struct drm_dp_aux *aux, struct drm_dp_link *link);
 int drm_dp_link_configure(struct drm_dp_aux *aux, struct drm_dp_link *link);
 
+#define DRM_DP_ADD_AUX 0x01
+#define DRM_DP_DEL_AUX 0x02
+
 int drm_dp_aux_register(struct drm_dp_aux *aux);
 void drm_dp_aux_unregister(struct drm_dp_aux *aux);
+void drm_dp_aux_set_aux_dev(int (*fn)(int, struct drm_dp_aux *));
+int drm_dp_aux_for_each(void *data, int (*fn)(struct drm_dp_aux *, void *));
 
 #endif /* _DRM_DP_HELPER_H_ */
-- 
2.4.3

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