1 files changed, 424 insertions, 38 deletions

diff --git a/drivers/gpu/drm/drm_panel.c b/drivers/gpu/drm/drm_panel.c
index f634371c717a..d1e6598ea3bc 100644
--- a/drivers/gpu/drm/drm_panel.c
+++ b/drivers/gpu/drm/drm_panel.c
@@ -23,7 +23,9 @@
 
 #include <linux/backlight.h>
 #include <linux/err.h>
+#include <linux/export.h>
 #include <linux/module.h>
+#include <linux/of.h>
 
 #include <drm/drm_crtc.h>
 #include <drm/drm_panel.h>
@@ -49,7 +51,7 @@ static LIST_HEAD(panel_list);
  * @dev: parent device of the panel
  * @funcs: panel operations
  * @connector_type: the connector type (DRM_MODE_CONNECTOR_*) corresponding to
- *	the panel interface
+ *	the panel interface (must NOT be DRM_MODE_CONNECTOR_Unknown)
  *
  * Initialize the panel structure for subsequent registration with
  * drm_panel_add().
@@ -57,7 +59,12 @@ static LIST_HEAD(panel_list);
 void drm_panel_init(struct drm_panel *panel, struct device *dev,
 		    const struct drm_panel_funcs *funcs, int connector_type)
 {
+	if (connector_type == DRM_MODE_CONNECTOR_Unknown)
+		DRM_WARN("%s: %s: a valid connector type is required!\n", __func__, dev_name(dev));
+
 	INIT_LIST_HEAD(&panel->list);
+	INIT_LIST_HEAD(&panel->followers);
+	mutex_init(&panel->follower_lock);
 	panel->dev = dev;
 	panel->funcs = funcs;
 	panel->connector_type = connector_type;
@@ -68,8 +75,9 @@ EXPORT_SYMBOL(drm_panel_init);
  * drm_panel_add - add a panel to the global registry
  * @panel: panel to add
  *
- * Add a panel to the global registry so that it can be looked up by display
- * drivers.
+ * Add a panel to the global registry so that it can be looked
+ * up by display drivers. The panel to be added must have been
+ * allocated by devm_drm_panel_alloc().
  */
 void drm_panel_add(struct drm_panel *panel)
 {
@@ -99,19 +107,44 @@ EXPORT_SYMBOL(drm_panel_remove);
  *
  * Calling this function will enable power and deassert any reset signals to
  * the panel. After this has completed it is possible to communicate with any
- * integrated circuitry via a command bus.
- *
- * Return: 0 on success or a negative error code on failure.
+ * integrated circuitry via a command bus. This function cannot fail (as it is
+ * called from the pre_enable call chain). There will always be a call to
+ * drm_panel_disable() afterwards.
  */
-int drm_panel_prepare(struct drm_panel *panel)
+void drm_panel_prepare(struct drm_panel *panel)
 {
+	struct drm_panel_follower *follower;
+	int ret;
+
 	if (!panel)
-		return -EINVAL;
+		return;
 
-	if (panel->funcs && panel->funcs->prepare)
-		return panel->funcs->prepare(panel);
+	if (panel->prepared) {
+		dev_warn(panel->dev, "Skipping prepare of already prepared panel\n");
+		return;
+	}
 
-	return 0;
+	mutex_lock(&panel->follower_lock);
+
+	if (panel->funcs && panel->funcs->prepare) {
+		ret = panel->funcs->prepare(panel);
+		if (ret < 0)
+			goto exit;
+	}
+	panel->prepared = true;
+
+	list_for_each_entry(follower, &panel->followers, list) {
+		if (!follower->funcs->panel_prepared)
+			continue;
+
+		ret = follower->funcs->panel_prepared(follower);
+		if (ret < 0)
+			dev_info(panel->dev, "%ps failed: %d\n",
+				 follower->funcs->panel_prepared, ret);
+	}
+
+exit:
+	mutex_unlock(&panel->follower_lock);
 }
 EXPORT_SYMBOL(drm_panel_prepare);
 
@@ -123,18 +156,50 @@ EXPORT_SYMBOL(drm_panel_prepare);
  * reset, turn off power supplies, ...). After this function has completed, it
  * is usually no longer possible to communicate with the panel until another
  * call to drm_panel_prepare().
- *
- * Return: 0 on success or a negative error code on failure.
  */
-int drm_panel_unprepare(struct drm_panel *panel)
+void drm_panel_unprepare(struct drm_panel *panel)
 {
+	struct drm_panel_follower *follower;
+	int ret;
+
 	if (!panel)
-		return -EINVAL;
+		return;
+
+	/*
+	 * If you are seeing the warning below it likely means one of two things:
+	 * - Your panel driver incorrectly calls drm_panel_unprepare() in its
+	 *   shutdown routine. You should delete this.
+	 * - You are using panel-edp or panel-simple and your DRM modeset
+	 *   driver's shutdown() callback happened after the panel's shutdown().
+	 *   In this case the warning is harmless though ideally you should
+	 *   figure out how to reverse the order of the shutdown() callbacks.
+	 */
+	if (!panel->prepared) {
+		dev_warn(panel->dev, "Skipping unprepare of already unprepared panel\n");
+		return;
+	}
 
-	if (panel->funcs && panel->funcs->unprepare)
-		return panel->funcs->unprepare(panel);
+	mutex_lock(&panel->follower_lock);
 
-	return 0;
+	list_for_each_entry(follower, &panel->followers, list) {
+		if (!follower->funcs->panel_unpreparing)
+			continue;
+
+		ret = follower->funcs->panel_unpreparing(follower);
+		if (ret < 0)
+			dev_info(panel->dev, "%ps failed: %d\n",
+				 follower->funcs->panel_unpreparing, ret);
+	}
+
+	if (panel->funcs && panel->funcs->unprepare) {
+		ret = panel->funcs->unprepare(panel);
+		if (ret < 0)
+			goto exit;
+	}
+	panel->prepared = false;
+
+exit:
+	mutex_unlock(&panel->follower_lock);
 }
 EXPORT_SYMBOL(drm_panel_unprepare);
 
@@ -144,29 +209,49 @@ EXPORT_SYMBOL(drm_panel_unprepare);
  *
  * Calling this function will cause the panel display drivers to be turned on
  * and the backlight to be enabled. Content will be visible on screen after
- * this call completes.
- *
- * Return: 0 on success or a negative error code on failure.
+ * this call completes. This function cannot fail (as it is called from the
+ * enable call chain). There will always be a call to drm_panel_disable()
+ * afterwards.
  */
-int drm_panel_enable(struct drm_panel *panel)
+void drm_panel_enable(struct drm_panel *panel)
 {
+	struct drm_panel_follower *follower;
 	int ret;
 
 	if (!panel)
-		return -EINVAL;
+		return;
+
+	if (panel->enabled) {
+		dev_warn(panel->dev, "Skipping enable of already enabled panel\n");
+		return;
+	}
+
+	mutex_lock(&panel->follower_lock);
 
 	if (panel->funcs && panel->funcs->enable) {
 		ret = panel->funcs->enable(panel);
 		if (ret < 0)
-			return ret;
+			goto exit;
 	}
+	panel->enabled = true;
 
 	ret = backlight_enable(panel->backlight);
 	if (ret < 0)
 		DRM_DEV_INFO(panel->dev, "failed to enable backlight: %d\n",
 			     ret);
 
-	return 0;
+	list_for_each_entry(follower, &panel->followers, list) {
+		if (!follower->funcs->panel_enabled)
+			continue;
+
+		ret = follower->funcs->panel_enabled(follower);
+		if (ret < 0)
+			dev_info(panel->dev, "%ps failed: %d\n",
+				 follower->funcs->panel_enabled, ret);
+	}
+
+exit:
+	mutex_unlock(&panel->follower_lock);
 }
 EXPORT_SYMBOL(drm_panel_enable);
 
@@ -177,25 +262,55 @@ EXPORT_SYMBOL(drm_panel_enable);
  * This will typically turn off the panel's backlight or disable the display
  * drivers. For smart panels it should still be possible to communicate with
  * the integrated circuitry via any command bus after this call.
- *
- * Return: 0 on success or a negative error code on failure.
  */
-int drm_panel_disable(struct drm_panel *panel)
+void drm_panel_disable(struct drm_panel *panel)
 {
+	struct drm_panel_follower *follower;
 	int ret;
 
 	if (!panel)
-		return -EINVAL;
+		return;
+
+	/*
+	 * If you are seeing the warning below it likely means one of two things:
+	 * - Your panel driver incorrectly calls drm_panel_disable() in its
+	 *   shutdown routine. You should delete this.
+	 * - You are using panel-edp or panel-simple and your DRM modeset
+	 *   driver's shutdown() callback happened after the panel's shutdown().
+	 *   In this case the warning is harmless though ideally you should
+	 *   figure out how to reverse the order of the shutdown() callbacks.
+	 */
+	if (!panel->enabled) {
+		dev_warn(panel->dev, "Skipping disable of already disabled panel\n");
+		return;
+	}
+
+	mutex_lock(&panel->follower_lock);
+
+	list_for_each_entry(follower, &panel->followers, list) {
+		if (!follower->funcs->panel_disabling)
+			continue;
+
+		ret = follower->funcs->panel_disabling(follower);
+		if (ret < 0)
+			dev_info(panel->dev, "%ps failed: %d\n",
+				 follower->funcs->panel_disabling, ret);
+	}
 
 	ret = backlight_disable(panel->backlight);
 	if (ret < 0)
 		DRM_DEV_INFO(panel->dev, "failed to disable backlight: %d\n",
 			     ret);
 
-	if (panel->funcs && panel->funcs->disable)
-		return panel->funcs->disable(panel);
+	if (panel->funcs && panel->funcs->disable) {
+		ret = panel->funcs->disable(panel);
+		if (ret < 0)
+			goto exit;
+	}
+	panel->enabled = false;
 
-	return 0;
+exit:
+	mutex_unlock(&panel->follower_lock);
 }
 EXPORT_SYMBOL(drm_panel_disable);
 
@@ -207,22 +322,114 @@ EXPORT_SYMBOL(drm_panel_disable);
  * The modes probed from the panel are automatically added to the connector
  * that the panel is attached to.
  *
- * Return: The number of modes available from the panel on success or a
- * negative error code on failure.
+ * Return: The number of modes available from the panel on success, or 0 on
+ * failure (no modes).
  */
 int drm_panel_get_modes(struct drm_panel *panel,
 			struct drm_connector *connector)
 {
 	if (!panel)
-		return -EINVAL;
+		return 0;
 
-	if (panel->funcs && panel->funcs->get_modes)
-		return panel->funcs->get_modes(panel, connector);
+	if (panel->funcs && panel->funcs->get_modes) {
+		int num;
 
-	return -EOPNOTSUPP;
+		num = panel->funcs->get_modes(panel, connector);
+		if (num > 0)
+			return num;
+	}
+
+	return 0;
 }
 EXPORT_SYMBOL(drm_panel_get_modes);
 
+static void __drm_panel_free(struct kref *kref)
+{
+	struct drm_panel *panel = container_of(kref, struct drm_panel, refcount);
+
+	kfree(panel->container);
+}
+
+/**
+ * drm_panel_get - Acquire a panel reference
+ * @panel: DRM panel
+ *
+ * This function increments the panel's refcount.
+ * Returns:
+ * Pointer to @panel
+ */
+struct drm_panel *drm_panel_get(struct drm_panel *panel)
+{
+	if (!panel)
+		return panel;
+
+	kref_get(&panel->refcount);
+
+	return panel;
+}
+EXPORT_SYMBOL(drm_panel_get);
+
+/**
+ * drm_panel_put - Release a panel reference
+ * @panel: DRM panel
+ *
+ * This function decrements the panel's reference count and frees the
+ * object if the reference count drops to zero.
+ */
+void drm_panel_put(struct drm_panel *panel)
+{
+	if (panel)
+		kref_put(&panel->refcount, __drm_panel_free);
+}
+EXPORT_SYMBOL(drm_panel_put);
+
+/**
+ * drm_panel_put_void - wrapper to drm_panel_put() taking a void pointer
+ *
+ * @data: pointer to @struct drm_panel, cast to a void pointer
+ *
+ * Wrapper of drm_panel_put() to be used when a function taking a void
+ * pointer is needed, for example as a devm action.
+ */
+static void drm_panel_put_void(void *data)
+{
+	struct drm_panel *panel = (struct drm_panel *)data;
+
+	drm_panel_put(panel);
+}
+
+void *__devm_drm_panel_alloc(struct device *dev, size_t size, size_t offset,
+			     const struct drm_panel_funcs *funcs,
+			     int connector_type)
+{
+	void *container;
+	struct drm_panel *panel;
+	int err;
+
+	if (!funcs) {
+		dev_warn(dev, "Missing funcs pointer\n");
+		return ERR_PTR(-EINVAL);
+	}
+
+	container = kzalloc(size, GFP_KERNEL);
+	if (!container)
+		return ERR_PTR(-ENOMEM);
+
+	panel = container + offset;
+	panel->container = container;
+	panel->funcs = funcs;
+	kref_init(&panel->refcount);
+
+	err = devm_add_action_or_reset(dev, drm_panel_put_void, panel);
+	if (err)
+		return ERR_PTR(err);
+
+	drm_panel_init(panel, dev, funcs, connector_type);
+
+	return container;
+}
+EXPORT_SYMBOL(__devm_drm_panel_alloc);
+
 #ifdef CONFIG_OF
 /**
  * of_drm_find_panel - look up a panel using a device tree node
@@ -305,6 +512,185 @@ int of_drm_get_panel_orientation(const struct device_node *np,
 EXPORT_SYMBOL(of_drm_get_panel_orientation);
 #endif
 
+/* Find panel by fwnode. This should be identical to of_drm_find_panel(). */
+static struct drm_panel *find_panel_by_fwnode(const struct fwnode_handle *fwnode)
+{
+	struct drm_panel *panel;
+
+	if (!fwnode_device_is_available(fwnode))
+		return ERR_PTR(-ENODEV);
+
+	mutex_lock(&panel_lock);
+
+	list_for_each_entry(panel, &panel_list, list) {
+		if (dev_fwnode(panel->dev) == fwnode) {
+			mutex_unlock(&panel_lock);
+			return panel;
+		}
+	}
+
+	mutex_unlock(&panel_lock);
+
+	return ERR_PTR(-EPROBE_DEFER);
+}
+
+/* Find panel by follower device */
+static struct drm_panel *find_panel_by_dev(struct device *follower_dev)
+{
+	struct fwnode_handle *fwnode;
+	struct drm_panel *panel;
+
+	fwnode = fwnode_find_reference(dev_fwnode(follower_dev), "panel", 0);
+	if (IS_ERR(fwnode))
+		return ERR_PTR(-ENODEV);
+
+	panel = find_panel_by_fwnode(fwnode);
+	fwnode_handle_put(fwnode);
+
+	return panel;
+}
+
+/**
+ * drm_is_panel_follower() - Check if the device is a panel follower
+ * @dev: The 'struct device' to check
+ *
+ * This checks to see if a device needs to be power sequenced together with
+ * a panel using the panel follower API.
+ *
+ * The "panel" property of the follower points to the panel to be followed.
+ *
+ * Return: true if we should be power sequenced with a panel; false otherwise.
+ */
+bool drm_is_panel_follower(struct device *dev)
+{
+	/*
+	 * The "panel" property is actually a phandle, but for simplicity we
+	 * don't bother trying to parse it here. We just need to know if the
+	 * property is there.
+	 */
+	return device_property_present(dev, "panel");
+}
+EXPORT_SYMBOL(drm_is_panel_follower);
+
+/**
+ * drm_panel_add_follower() - Register something to follow panel state.
+ * @follower_dev: The 'struct device' for the follower.
+ * @follower:     The panel follower descriptor for the follower.
+ *
+ * A panel follower is called right after preparing/enabling the panel and right
+ * before unpreparing/disabling the panel. It's primary intention is to power on
+ * an associated touchscreen, though it could be used for any similar devices.
+ * Multiple devices are allowed the follow the same panel.
+ *
+ * If a follower is added to a panel that's already been prepared/enabled, the
+ * follower's prepared/enabled callback is called right away.
+ *
+ * The "panel" property of the follower points to the panel to be followed.
+ *
+ * Return: 0 or an error code. Note that -ENODEV means that we detected that
+ *         follower_dev is not actually following a panel. The caller may
+ *         choose to ignore this return value if following a panel is optional.
+ */
+int drm_panel_add_follower(struct device *follower_dev,
+			   struct drm_panel_follower *follower)
+{
+	struct drm_panel *panel;
+	int ret;
+
+	panel = find_panel_by_dev(follower_dev);
+	if (IS_ERR(panel))
+		return PTR_ERR(panel);
+
+	get_device(panel->dev);
+	follower->panel = panel;
+
+	mutex_lock(&panel->follower_lock);
+
+	list_add_tail(&follower->list, &panel->followers);
+	if (panel->prepared && follower->funcs->panel_prepared) {
+		ret = follower->funcs->panel_prepared(follower);
+		if (ret < 0)
+			dev_info(panel->dev, "%ps failed: %d\n",
+				 follower->funcs->panel_prepared, ret);
+	}
+	if (panel->enabled && follower->funcs->panel_enabled) {
+		ret = follower->funcs->panel_enabled(follower);
+		if (ret < 0)
+			dev_info(panel->dev, "%ps failed: %d\n",
+				 follower->funcs->panel_enabled, ret);
+	}
+
+	mutex_unlock(&panel->follower_lock);
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_panel_add_follower);
+
+/**
+ * drm_panel_remove_follower() - Reverse drm_panel_add_follower().
+ * @follower:     The panel follower descriptor for the follower.
+ *
+ * Undo drm_panel_add_follower(). This includes calling the follower's
+ * unpreparing/disabling function if we're removed from a panel that's currently
+ * prepared/enabled.
+ *
+ * Return: 0 or an error code.
+ */
+void drm_panel_remove_follower(struct drm_panel_follower *follower)
+{
+	struct drm_panel *panel = follower->panel;
+	int ret;
+
+	mutex_lock(&panel->follower_lock);
+
+	if (panel->enabled && follower->funcs->panel_disabling) {
+		ret = follower->funcs->panel_disabling(follower);
+		if (ret < 0)
+			dev_info(panel->dev, "%ps failed: %d\n",
+				 follower->funcs->panel_disabling, ret);
+	}
+	if (panel->prepared && follower->funcs->panel_unpreparing) {
+		ret = follower->funcs->panel_unpreparing(follower);
+		if (ret < 0)
+			dev_info(panel->dev, "%ps failed: %d\n",
+				 follower->funcs->panel_unpreparing, ret);
+	}
+	list_del_init(&follower->list);
+
+	mutex_unlock(&panel->follower_lock);
+
+	put_device(panel->dev);
+}
+EXPORT_SYMBOL(drm_panel_remove_follower);
+
+static void drm_panel_remove_follower_void(void *follower)
+{
+	drm_panel_remove_follower(follower);
+}
+
+/**
+ * devm_drm_panel_add_follower() - devm version of drm_panel_add_follower()
+ * @follower_dev: The 'struct device' for the follower.
+ * @follower:     The panel follower descriptor for the follower.
+ *
+ * Handles calling drm_panel_remove_follower() using devm on the follower_dev.
+ *
+ * Return: 0 or an error code.
+ */
+int devm_drm_panel_add_follower(struct device *follower_dev,
+				struct drm_panel_follower *follower)
+{
+	int ret;
+
+	ret = drm_panel_add_follower(follower_dev, follower);
+	if (ret)
+		return ret;
+
+	return devm_add_action_or_reset(follower_dev,
+					drm_panel_remove_follower_void, follower);
+}
+EXPORT_SYMBOL(devm_drm_panel_add_follower);
+
 #if IS_REACHABLE(CONFIG_BACKLIGHT_CLASS_DEVICE)
 /**
  * drm_panel_of_backlight - use backlight device node for backlight