// 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 { … }; /** * 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, const struct device_driver *drv) { … } /** * 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) { … } /** * 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) { … } /** * 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) { … } static const struct bus_type dp_aux_bus_type = …; static ssize_t modalias_show(struct device *dev, struct device_attribute *attr, char *buf) { … } static DEVICE_ATTR_RO(modalias); static struct attribute *dp_aux_ep_dev_attrs[] = …; ATTRIBUTE_GROUPS(…); /** * 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) { … } static int dp_aux_ep_dev_modalias(const struct device *dev, struct kobj_uevent_env *env) { … } static struct device_type dp_aux_device_type_type = …; /** * 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) { … } /** * 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) { … } EXPORT_SYMBOL_GPL(…); /** * 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)) { … } EXPORT_SYMBOL_GPL(…); static void of_dp_aux_depopulate_bus_void(void *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)) { … } EXPORT_SYMBOL_GPL(…); int __dp_aux_dp_driver_register(struct dp_aux_ep_driver *drv, struct module *owner) { … } EXPORT_SYMBOL_GPL(…); void dp_aux_dp_driver_unregister(struct dp_aux_ep_driver *drv) { … } EXPORT_SYMBOL_GPL(…); static int __init dp_aux_bus_init(void) { … } static void __exit dp_aux_bus_exit(void) { … } subsys_initcall(dp_aux_bus_init); module_exit(dp_aux_bus_exit); MODULE_AUTHOR(…) …; MODULE_DESCRIPTION(…) …; MODULE_LICENSE(…) …;
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