--- /dev/null
- * Return: 0 if no error or negative error code.
+// 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 devices on the far side of the bus are referred to as
+ * endpoints in this code.
+ *
+ * Commonly there is only one device connected to the DP AUX bus: a 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/drm_dp_aux_bus.h>
+#include <drm/drm_dp_helper.h>
+
+/**
+ * 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);
+ 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)
+ 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 int dp_aux_ep_remove(struct device *dev)
+ */
-
- return 0;
++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.
+ *
+ * Return: 0 if no error or negative error code.
+ */
+static void dp_aux_ep_dev_release(struct device *dev)
+{
+ kfree(to_dp_aux_ep_dev(dev));
+}
+
+static struct device_type dp_aux_device_type_type = {
+ .groups = dp_aux_ep_dev_groups,
+ .uevent = of_device_uevent_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_ep_devices() 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 the loop
+ * in of_dp_aux_populate_ep_devices().
+ *
+ * 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_ep_devices() - Undo of_dp_aux_populate_ep_devices
+ * @aux: The AUX channel whose devices we want to depopulate
+ *
+ * This will destroy all devices that were created
+ * by of_dp_aux_populate_ep_devices().
+ */
+void of_dp_aux_depopulate_ep_devices(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_ep_devices);
+
+/**
+ * of_dp_aux_populate_ep_devices() - Populate the endpoint devices on the DP AUX
+ * @aux: The AUX channel whose devices we want to populate. It is required that
+ * drm_dp_aux_init() has already been called for this AUX channel.
+ *
+ * This will populate all the devices 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-devices will have finished probing. It should be noted that if our
+ * sub-devices return -EPROBE_DEFER that we will not return any error codes
+ * ourselves but our sub-devices will _not_ have actually probed successfully
+ * yet. There may be other cases (maybe added in the future?) where sub-devices
+ * won't have been probed yet when this function returns, so it's best not to
+ * rely on that.
+ *
+ * If this function succeeds you should later make sure you call
+ * of_dp_aux_depopulate_ep_devices() to undo it, or just use the devm version
+ * of this function.
+ *
+ * Return: 0 if no error or negative error code.
+ */
+int of_dp_aux_populate_ep_devices(struct drm_dp_aux *aux)
+{
+ struct device_node *bus, *np;
+ struct dp_aux_ep_device *aux_ep;
+ 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 0;
+
+ bus = of_get_child_by_name(aux->dev->of_node, "aux-bus");
+ if (!bus)
+ return 0;
+
+ for_each_available_child_of_node(bus, np) {
+ if (of_node_test_and_set_flag(np, OF_POPULATED))
+ continue;
+
+ aux_ep = kzalloc(sizeof(*aux_ep), GFP_KERNEL);
+ if (!aux_ep)
+ continue;
+ 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);
+ of_node_clear_flag(np, OF_POPULATED);
+ of_node_put(np);
+
+ /*
+ * As per docs of device_register(), call this instead
+ * of kfree() directly for error cases.
+ */
+ put_device(&aux_ep->dev);
+
+ /*
+ * Following in the footsteps of of_i2c_register_devices(),
+ * we won't fail the whole function here--we'll just
+ * continue registering any other devices we find.
+ */
+ }
+ }
+
+ of_node_put(bus);
+
+ return 0;
+}
+
+static void of_dp_aux_depopulate_ep_devices_void(void *data)
+{
+ of_dp_aux_depopulate_ep_devices(data);
+}
+
+/**
+ * devm_of_dp_aux_populate_ep_devices() - devm wrapper for of_dp_aux_populate_ep_devices()
+ * @aux: The AUX channel whose devices we want to populate
+ *
+ * Handles freeing w/ devm on the device "aux->dev".
+ *
+ * Return: 0 if no error or negative error code.
+ */
+int devm_of_dp_aux_populate_ep_devices(struct drm_dp_aux *aux)
+{
+ int ret;
+
+ ret = of_dp_aux_populate_ep_devices(aux);
+ if (ret)
+ return ret;
+
+ return devm_add_action_or_reset(aux->dev,
+ of_dp_aux_depopulate_ep_devices_void,
+ aux);
+}
+EXPORT_SYMBOL_GPL(devm_of_dp_aux_populate_ep_devices);
+
+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");
projects / linux-2.6-microblaze.git / commitdiff