Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 391 insertions, 0 deletions

diff --git a/drivers/gpu/drm/display/drm_dp_aux_bus.c b/drivers/gpu/drm/display/drm_dp_aux_bus.c
new file mode 100644
index 0000000000..8a165be1a8
--- /dev/null
+++ b/drivers/gpu/drm/display/drm_dp_aux_bus.c
@@ -0,0 +1,391 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2021 Google Inc.
+ *
+ * The DP AUX bus is used for devices that are connected over a DisplayPort
+ * AUX bus. The device on the far side of the bus is referred to as an
+ * endpoint in this code.
+ *
+ * There is only one device connected to the DP AUX bus: an eDP panel.
+ * Though historically panels (even DP panels) have been modeled as simple
+ * platform devices, putting them under the DP AUX bus allows the panel driver
+ * to perform transactions on that bus.
+ */
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/pm_domain.h>
+#include <linux/pm_runtime.h>
+
+#include <drm/display/drm_dp_aux_bus.h>
+#include <drm/display/drm_dp_helper.h>
+
+struct dp_aux_ep_device_with_data {
+	struct dp_aux_ep_device aux_ep;
+	int (*done_probing)(struct drm_dp_aux *aux);
+};
+
+/**
+ * dp_aux_ep_match() - The match function for the dp_aux_bus.
+ * @dev: The device to match.
+ * @drv: The driver to try to match against.
+ *
+ * At the moment, we just match on device tree.
+ *
+ * Return: True if this driver matches this device; false otherwise.
+ */
+static int dp_aux_ep_match(struct device *dev, struct device_driver *drv)
+{
+	return !!of_match_device(drv->of_match_table, dev);
+}
+
+/**
+ * dp_aux_ep_probe() - The probe function for the dp_aux_bus.
+ * @dev: The device to probe.
+ *
+ * Calls through to the endpoint driver probe.
+ *
+ * Return: 0 if no error or negative error code.
+ */
+static int dp_aux_ep_probe(struct device *dev)
+{
+	struct dp_aux_ep_driver *aux_ep_drv = to_dp_aux_ep_drv(dev->driver);
+	struct dp_aux_ep_device *aux_ep = to_dp_aux_ep_dev(dev);
+	struct dp_aux_ep_device_with_data *aux_ep_with_data =
+		container_of(aux_ep, struct dp_aux_ep_device_with_data, aux_ep);
+	int ret;
+
+	ret = dev_pm_domain_attach(dev, true);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to attach to PM Domain\n");
+
+	ret = aux_ep_drv->probe(aux_ep);
+	if (ret)
+		goto err_attached;
+
+	if (aux_ep_with_data->done_probing) {
+		ret = aux_ep_with_data->done_probing(aux_ep->aux);
+		if (ret) {
+			/*
+			 * The done_probing() callback should not return
+			 * -EPROBE_DEFER to us. If it does, we treat it as an
+			 * error. Passing it on as-is would cause the _panel_
+			 * to defer.
+			 */
+			if (ret == -EPROBE_DEFER) {
+				dev_err(dev,
+					"DP AUX done_probing() can't defer\n");
+				ret = -EINVAL;
+			}
+			goto err_probed;
+		}
+	}
+
+	return 0;
+err_probed:
+	if (aux_ep_drv->remove)
+		aux_ep_drv->remove(aux_ep);
+err_attached:
+	dev_pm_domain_detach(dev, true);
+
+	return ret;
+}
+
+/**
+ * dp_aux_ep_remove() - The remove function for the dp_aux_bus.
+ * @dev: The device to remove.
+ *
+ * Calls through to the endpoint driver remove.
+ */
+static void dp_aux_ep_remove(struct device *dev)
+{
+	struct dp_aux_ep_driver *aux_ep_drv = to_dp_aux_ep_drv(dev->driver);
+	struct dp_aux_ep_device *aux_ep = to_dp_aux_ep_dev(dev);
+
+	if (aux_ep_drv->remove)
+		aux_ep_drv->remove(aux_ep);
+	dev_pm_domain_detach(dev, true);
+}
+
+/**
+ * dp_aux_ep_shutdown() - The shutdown function for the dp_aux_bus.
+ * @dev: The device to shutdown.
+ *
+ * Calls through to the endpoint driver shutdown.
+ */
+static void dp_aux_ep_shutdown(struct device *dev)
+{
+	struct dp_aux_ep_driver *aux_ep_drv;
+
+	if (!dev->driver)
+		return;
+
+	aux_ep_drv = to_dp_aux_ep_drv(dev->driver);
+	if (aux_ep_drv->shutdown)
+		aux_ep_drv->shutdown(to_dp_aux_ep_dev(dev));
+}
+
+static struct bus_type dp_aux_bus_type = {
+	.name		= "dp-aux",
+	.match		= dp_aux_ep_match,
+	.probe		= dp_aux_ep_probe,
+	.remove		= dp_aux_ep_remove,
+	.shutdown	= dp_aux_ep_shutdown,
+};
+
+static ssize_t modalias_show(struct device *dev,
+			     struct device_attribute *attr, char *buf)
+{
+	return of_device_modalias(dev, buf, PAGE_SIZE);
+}
+static DEVICE_ATTR_RO(modalias);
+
+static struct attribute *dp_aux_ep_dev_attrs[] = {
+	&dev_attr_modalias.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(dp_aux_ep_dev);
+
+/**
+ * dp_aux_ep_dev_release() - Free memory for the dp_aux_ep device
+ * @dev: The device to free.
+ */
+static void dp_aux_ep_dev_release(struct device *dev)
+{
+	struct dp_aux_ep_device *aux_ep = to_dp_aux_ep_dev(dev);
+	struct dp_aux_ep_device_with_data *aux_ep_with_data =
+		container_of(aux_ep, struct dp_aux_ep_device_with_data, aux_ep);
+
+	kfree(aux_ep_with_data);
+}
+
+static int dp_aux_ep_dev_modalias(const struct device *dev, struct kobj_uevent_env *env)
+{
+	return of_device_uevent_modalias(dev, env);
+}
+
+static struct device_type dp_aux_device_type_type = {
+	.groups		= dp_aux_ep_dev_groups,
+	.uevent		= dp_aux_ep_dev_modalias,
+	.release	= dp_aux_ep_dev_release,
+};
+
+/**
+ * of_dp_aux_ep_destroy() - Destroy an DP AUX endpoint device
+ * @dev: The device to destroy.
+ * @data: Not used
+ *
+ * This is just used as a callback by of_dp_aux_depopulate_bus() and
+ * is called for _all_ of the child devices of the device providing the AUX bus.
+ * We'll only act on those that are of type "dp_aux_bus_type".
+ *
+ * This function is effectively an inverse of what's in
+ * of_dp_aux_populate_bus(). NOTE: since we only populate one child
+ * then it's expected that only one device will match all the "if" tests in
+ * this function and get to the device_unregister().
+ *
+ * Return: 0 if no error or negative error code.
+ */
+static int of_dp_aux_ep_destroy(struct device *dev, void *data)
+{
+	struct device_node *np = dev->of_node;
+
+	if (dev->bus != &dp_aux_bus_type)
+		return 0;
+
+	if (!of_node_check_flag(np, OF_POPULATED))
+		return 0;
+
+	of_node_clear_flag(np, OF_POPULATED);
+	of_node_put(np);
+
+	device_unregister(dev);
+
+	return 0;
+}
+
+/**
+ * of_dp_aux_depopulate_bus() - Undo of_dp_aux_populate_bus
+ * @aux: The AUX channel whose device we want to depopulate
+ *
+ * This will destroy the device that was created
+ * by of_dp_aux_populate_bus().
+ */
+void of_dp_aux_depopulate_bus(struct drm_dp_aux *aux)
+{
+	device_for_each_child_reverse(aux->dev, NULL, of_dp_aux_ep_destroy);
+}
+EXPORT_SYMBOL_GPL(of_dp_aux_depopulate_bus);
+
+/**
+ * of_dp_aux_populate_bus() - Populate the endpoint device on the DP AUX
+ * @aux: The AUX channel whose device we want to populate. It is required that
+ *       drm_dp_aux_init() has already been called for this AUX channel.
+ * @done_probing: Callback functions to call after EP device finishes probing.
+ *                Will not be called if there are no EP devices and this
+ *                function will return -ENODEV.
+ *
+ * This will populate the device (expected to be an eDP panel) under the
+ * "aux-bus" node of the device providing the AUX channel (AKA aux->dev).
+ *
+ * When this function finishes, it is _possible_ (but not guaranteed) that
+ * our sub-device will have finished probing. It should be noted that if our
+ * sub-device returns -EPROBE_DEFER or is probing asynchronously for some
+ * reason that we will not return any error codes ourselves but our
+ * sub-device will _not_ have actually probed successfully yet.
+ *
+ * In many cases it's important for the caller of this function to be notified
+ * when our sub device finishes probing. Our sub device is expected to be an
+ * eDP panel and the caller is expected to be an eDP controller. The eDP
+ * controller needs to be able to get a reference to the panel when it finishes
+ * probing. For this reason the caller can pass in a function pointer that
+ * will be called when our sub-device finishes probing.
+ *
+ * If this function succeeds you should later make sure you call
+ * of_dp_aux_depopulate_bus() to undo it, or just use the devm version
+ * of this function.
+ *
+ * Return: 0 if no error or negative error code; returns -ENODEV if there are
+ *         no children. The done_probing() function won't be called in that
+ *         case.
+ */
+int of_dp_aux_populate_bus(struct drm_dp_aux *aux,
+			   int (*done_probing)(struct drm_dp_aux *aux))
+{
+	struct device_node *bus = NULL, *np = NULL;
+	struct dp_aux_ep_device *aux_ep;
+	struct dp_aux_ep_device_with_data *aux_ep_with_data;
+	int ret;
+
+	/* drm_dp_aux_init() should have been called already; warn if not */
+	WARN_ON_ONCE(!aux->ddc.algo);
+
+	if (!aux->dev->of_node)
+		return -ENODEV;
+	bus = of_get_child_by_name(aux->dev->of_node, "aux-bus");
+	if (!bus)
+		return -ENODEV;
+
+	np = of_get_next_available_child(bus, NULL);
+	of_node_put(bus);
+	if (!np)
+		return -ENODEV;
+
+	if (of_node_test_and_set_flag(np, OF_POPULATED)) {
+		dev_err(aux->dev, "DP AUX EP device already populated\n");
+		ret = -EINVAL;
+		goto err_did_get_np;
+	}
+
+	aux_ep_with_data = kzalloc(sizeof(*aux_ep_with_data), GFP_KERNEL);
+	if (!aux_ep_with_data) {
+		ret = -ENOMEM;
+		goto err_did_set_populated;
+	}
+
+	aux_ep_with_data->done_probing = done_probing;
+
+	aux_ep = &aux_ep_with_data->aux_ep;
+	aux_ep->aux = aux;
+	aux_ep->dev.parent = aux->dev;
+	aux_ep->dev.bus = &dp_aux_bus_type;
+	aux_ep->dev.type = &dp_aux_device_type_type;
+	aux_ep->dev.of_node = of_node_get(np);
+	dev_set_name(&aux_ep->dev, "aux-%s", dev_name(aux->dev));
+
+	ret = device_register(&aux_ep->dev);
+	if (ret) {
+		dev_err(aux->dev, "Failed to create AUX EP for %pOF: %d\n", np, ret);
+
+		/*
+		 * As per docs of device_register(), call this instead
+		 * of kfree() directly for error cases.
+		 */
+		put_device(&aux_ep->dev);
+
+		goto err_did_set_populated;
+	}
+
+	return 0;
+
+err_did_set_populated:
+	of_node_clear_flag(np, OF_POPULATED);
+
+err_did_get_np:
+	of_node_put(np);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(of_dp_aux_populate_bus);
+
+static void of_dp_aux_depopulate_bus_void(void *data)
+{
+	of_dp_aux_depopulate_bus(data);
+}
+
+/**
+ * devm_of_dp_aux_populate_bus() - devm wrapper for of_dp_aux_populate_bus()
+ * @aux: The AUX channel whose device we want to populate
+ * @done_probing: Callback functions to call after EP device finishes probing.
+ *                Will not be called if there are no EP devices and this
+ *                function will return -ENODEV.
+ *
+ * Handles freeing w/ devm on the device "aux->dev".
+ *
+ * Return: 0 if no error or negative error code; returns -ENODEV if there are
+ *         no children. The done_probing() function won't be called in that
+ *         case.
+ */
+int devm_of_dp_aux_populate_bus(struct drm_dp_aux *aux,
+				int (*done_probing)(struct drm_dp_aux *aux))
+{
+	int ret;
+
+	ret = of_dp_aux_populate_bus(aux, done_probing);
+	if (ret)
+		return ret;
+
+	return devm_add_action_or_reset(aux->dev,
+					of_dp_aux_depopulate_bus_void, aux);
+}
+EXPORT_SYMBOL_GPL(devm_of_dp_aux_populate_bus);
+
+int __dp_aux_dp_driver_register(struct dp_aux_ep_driver *drv, struct module *owner)
+{
+	drv->driver.owner = owner;
+	drv->driver.bus = &dp_aux_bus_type;
+
+	return driver_register(&drv->driver);
+}
+EXPORT_SYMBOL_GPL(__dp_aux_dp_driver_register);
+
+void dp_aux_dp_driver_unregister(struct dp_aux_ep_driver *drv)
+{
+	driver_unregister(&drv->driver);
+}
+EXPORT_SYMBOL_GPL(dp_aux_dp_driver_unregister);
+
+static int __init dp_aux_bus_init(void)
+{
+	int ret;
+
+	ret = bus_register(&dp_aux_bus_type);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static void __exit dp_aux_bus_exit(void)
+{
+	bus_unregister(&dp_aux_bus_type);
+}
+
+subsys_initcall(dp_aux_bus_init);
+module_exit(dp_aux_bus_exit);
+
+MODULE_AUTHOR("Douglas Anderson <dianders@chromium.org>");
+MODULE_DESCRIPTION("DRM DisplayPort AUX bus");
+MODULE_LICENSE("GPL v2");