usb/typec/retimer.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 /*
0003  * Copyright 2022 Google LLC
0004  *
0005  * USB Type-C Retimer support.
0006  * Author: Prashant Malani <pmalani@chromium.org>
0007  *
0008  */
0009
0010 #include <linux/device.h>
0011 #include <linux/list.h>
0012 #include <linux/module.h>
0013 #include <linux/mutex.h>
0014 #include <linux/property.h>
0015 #include <linux/slab.h>
0016
0017 #include "class.h"
0018 #include "retimer.h"
0019
0020 static bool dev_name_ends_with(struct device *dev, const char *suffix)
0021 {
0022     const char *name = dev_name(dev);
0023     const int name_len = strlen(name);
0024     const int suffix_len = strlen(suffix);
0025
0026     if (suffix_len > name_len)
0027         return false;
0028
0029     return strcmp(name + (name_len - suffix_len), suffix) == 0;
0030 }
0031
0032 static int retimer_fwnode_match(struct device *dev, const void *fwnode)
0033 {
0034     return dev_fwnode(dev) == fwnode && dev_name_ends_with(dev, "-retimer");
0035 }
0036
0037 static void *typec_retimer_match(struct fwnode_handle *fwnode, const char *id, void *data)
0038 {
0039     struct device *dev;
0040
0041     if (id && !fwnode_property_present(fwnode, id))
0042         return NULL;
0043
0044     dev = class_find_device(&retimer_class, NULL, fwnode,
0045                 retimer_fwnode_match);
0046
0047     return dev ? to_typec_retimer(dev) : ERR_PTR(-EPROBE_DEFER);
0048 }
0049
0050 /**
0051  * fwnode_typec_retimer_get - Find USB Type-C retimer.
0052  * @fwnode: The caller device node.
0053  *
0054  * Finds a retimer linked to the caller. This function is primarily meant for the
0055  * Type-C drivers. Returns a reference to the retimer on success, NULL if no
0056  * matching connection was found, or ERR_PTR(-EPROBE_DEFER) when a connection
0057  * was found but the retimer has not been enumerated yet.
0058  */
0059 struct typec_retimer *fwnode_typec_retimer_get(struct fwnode_handle *fwnode)
0060 {
0061     struct typec_retimer *retimer;
0062
0063     retimer = fwnode_connection_find_match(fwnode, "retimer-switch", NULL, typec_retimer_match);
0064     if (!IS_ERR_OR_NULL(retimer))
0065         WARN_ON(!try_module_get(retimer->dev.parent->driver->owner));
0066
0067     return retimer;
0068 }
0069 EXPORT_SYMBOL_GPL(fwnode_typec_retimer_get);
0070
0071 /**
0072  * typec_retimer_put - Release handle to a retimer.
0073  * @retimer: USB Type-C Connector Retimer.
0074  *
0075  * Decrements reference count for @retimer.
0076  */
0077 void typec_retimer_put(struct typec_retimer *retimer)
0078 {
0079     if (!IS_ERR_OR_NULL(retimer)) {
0080         module_put(retimer->dev.parent->driver->owner);
0081         put_device(&retimer->dev);
0082     }
0083 }
0084 EXPORT_SYMBOL_GPL(typec_retimer_put);
0085
0086 int typec_retimer_set(struct typec_retimer *retimer, struct typec_retimer_state *state)
0087 {
0088     if (IS_ERR_OR_NULL(retimer))
0089         return 0;
0090
0091     return retimer->set(retimer, state);
0092 }
0093 EXPORT_SYMBOL_GPL(typec_retimer_set);
0094
0095 static void typec_retimer_release(struct device *dev)
0096 {
0097     kfree(to_typec_retimer(dev));
0098 }
0099
0100 static const struct device_type typec_retimer_dev_type = {
0101     .name = "typec_retimer",
0102     .release = typec_retimer_release,
0103 };
0104
0105 /**
0106  * typec_retimer_register - Register a retimer device.
0107  * @parent: Parent device.
0108  * @desc: Retimer description.
0109  *
0110  * Some USB Type-C connectors have their physical lines routed through retimers before they
0111  * reach muxes or host controllers. In some cases (for example: using alternate modes)
0112  * these retimers need to be reconfigured appropriately. This function registers retimer
0113  * switches which route and potentially modify the signals on the Type C physical lines
0114  * enroute to the host controllers.
0115  */
0116 struct typec_retimer *
0117 typec_retimer_register(struct device *parent, const struct typec_retimer_desc *desc)
0118 {
0119     struct typec_retimer *retimer;
0120     int ret;
0121
0122     if (!desc || !desc->set)
0123         return ERR_PTR(-EINVAL);
0124
0125     retimer = kzalloc(sizeof(*retimer), GFP_KERNEL);
0126     if (!retimer)
0127         return ERR_PTR(-ENOMEM);
0128
0129     retimer->set = desc->set;
0130
0131     device_initialize(&retimer->dev);
0132     retimer->dev.parent = parent;
0133     retimer->dev.fwnode = desc->fwnode;
0134     retimer->dev.class = &retimer_class;
0135     retimer->dev.type = &typec_retimer_dev_type;
0136     retimer->dev.driver_data = desc->drvdata;
0137     dev_set_name(&retimer->dev, "%s-retimer",
0138              desc->name ? desc->name : dev_name(parent));
0139
0140     ret = device_add(&retimer->dev);
0141     if (ret) {
0142         dev_err(parent, "failed to register retimer (%d)\n", ret);
0143         put_device(&retimer->dev);
0144         return ERR_PTR(ret);
0145     }
0146
0147     return retimer;
0148 }
0149 EXPORT_SYMBOL_GPL(typec_retimer_register);
0150
0151 /**
0152  * typec_retimer_unregister - Unregister retimer device.
0153  * @retimer: USB Type-C Connector retimer.
0154  *
0155  * Unregister retimer that was registered with typec_retimer_register().
0156  */
0157 void typec_retimer_unregister(struct typec_retimer *retimer)
0158 {
0159     if (!IS_ERR_OR_NULL(retimer))
0160         device_unregister(&retimer->dev);
0161 }
0162 EXPORT_SYMBOL_GPL(typec_retimer_unregister);
0163
0164 void *typec_retimer_get_drvdata(struct typec_retimer *retimer)
0165 {
0166     return dev_get_drvdata(&retimer->dev);
0167 }
0168 EXPORT_SYMBOL_GPL(typec_retimer_get_drvdata);
0169
0170 struct class retimer_class = {
0171     .name = "retimer",
0172     .owner = THIS_MODULE,
0173 };