drivers/rpmsg/rpmsg_core.c - kernel/common - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * remote processor messaging bus
  *
  * Copyright (C) 2011 Texas Instruments, Inc.
  * Copyright (C) 2011 Google, Inc.
  *
  * Ohad Ben-Cohen <[email protected]>
  * Brian Swetland <[email protected]>
  */

 #define pr_fmt(fmt) "%s: " fmt, __func__

 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/rpmsg.h>
 #include <linux/of_device.h>
 #include <linux/pm_domain.h>
 #include <linux/slab.h>

 #include "rpmsg_internal.h"

 const struct class rpmsg_class = {
 	.name = "rpmsg",
 };
 EXPORT_SYMBOL(rpmsg_class);

 /**
  * rpmsg_create_channel() - create a new rpmsg channel
  * using its name and address info.
  * @rpdev: rpmsg device
  * @chinfo: channel_info to bind
  *
  * Return: a pointer to the new rpmsg device on success, or NULL on error.
  */
 struct rpmsg_device *rpmsg_create_channel(struct rpmsg_device *rpdev,
 					  struct rpmsg_channel_info *chinfo)
 {
 	if (WARN_ON(!rpdev))
 		return NULL;
 	if (!rpdev->ops || !rpdev->ops->create_channel) {
 		dev_err(&rpdev->dev, "no create_channel ops found\n");
 		return NULL;
 	}

 	return rpdev->ops->create_channel(rpdev, chinfo);
 }
 EXPORT_SYMBOL(rpmsg_create_channel);

 /**
  * rpmsg_release_channel() - release a rpmsg channel
  * using its name and address info.
  * @rpdev: rpmsg device
  * @chinfo: channel_info to bind
  *
  * Return: 0 on success or an appropriate error value.
  */
 int rpmsg_release_channel(struct rpmsg_device *rpdev,
 			  struct rpmsg_channel_info *chinfo)
 {
 	if (WARN_ON(!rpdev))
 		return -EINVAL;
 	if (!rpdev->ops || !rpdev->ops->release_channel) {
 		dev_err(&rpdev->dev, "no release_channel ops found\n");
 		return -ENXIO;
 	}

 	return rpdev->ops->release_channel(rpdev, chinfo);
 }
 EXPORT_SYMBOL(rpmsg_release_channel);

 /**
  * rpmsg_create_ept() - create a new rpmsg_endpoint
  * @rpdev: rpmsg channel device
  * @cb: rx callback handler
  * @priv: private data for the driver's use
  * @chinfo: channel_info with the local rpmsg address to bind with @cb
  *
  * Every rpmsg address in the system is bound to an rx callback (so when
  * inbound messages arrive, they are dispatched by the rpmsg bus using the
  * appropriate callback handler) by means of an rpmsg_endpoint struct.
  *
  * This function allows drivers to create such an endpoint, and by that,
  * bind a callback, and possibly some private data too, to an rpmsg address
  * (either one that is known in advance, or one that will be dynamically
  * assigned for them).
  *
  * Simple rpmsg drivers need not call rpmsg_create_ept, because an endpoint
  * is already created for them when they are probed by the rpmsg bus
  * (using the rx callback provided when they registered to the rpmsg bus).
  *
  * So things should just work for simple drivers: they already have an
  * endpoint, their rx callback is bound to their rpmsg address, and when
  * relevant inbound messages arrive (i.e. messages which their dst address
  * equals to the src address of their rpmsg channel), the driver's handler
  * is invoked to process it.
  *
  * That said, more complicated drivers might need to allocate
  * additional rpmsg addresses, and bind them to different rx callbacks.
  * To accomplish that, those drivers need to call this function.
  *
  * Drivers should provide their @rpdev channel (so the new endpoint would belong
  * to the same remote processor their channel belongs to), an rx callback
  * function, an optional private data (which is provided back when the
  * rx callback is invoked), and an address they want to bind with the
  * callback. If @addr is RPMSG_ADDR_ANY, then rpmsg_create_ept will
  * dynamically assign them an available rpmsg address (drivers should have
  * a very good reason why not to always use RPMSG_ADDR_ANY here).
  *
  * Return: a pointer to the endpoint on success, or NULL on error.
  */
 struct rpmsg_endpoint *rpmsg_create_ept(struct rpmsg_device *rpdev,
 					rpmsg_rx_cb_t cb, void *priv,
 					struct rpmsg_channel_info chinfo)
 {
 	if (WARN_ON(!rpdev))
 		return NULL;

 	return rpdev->ops->create_ept(rpdev, cb, priv, chinfo);
 }
 EXPORT_SYMBOL(rpmsg_create_ept);

 /**
  * rpmsg_destroy_ept() - destroy an existing rpmsg endpoint
  * @ept: endpoing to destroy
  *
  * Should be used by drivers to destroy an rpmsg endpoint previously
  * created with rpmsg_create_ept(). As with other types of "free" NULL
  * is a valid parameter.
  */
 void rpmsg_destroy_ept(struct rpmsg_endpoint *ept)
 {
 	if (ept && ept->ops)
 		ept->ops->destroy_ept(ept);
 }
 EXPORT_SYMBOL(rpmsg_destroy_ept);

 /**
  * rpmsg_send() - send a message across to the remote processor
  * @ept: the rpmsg endpoint
  * @data: payload of message
  * @len: length of payload
  *
  * This function sends @data of length @len on the @ept endpoint.
  * The message will be sent to the remote processor which the @ept
  * endpoint belongs to, using @ept's address and its associated rpmsg
  * device destination addresses.
  * In case there are no TX buffers available, the function will block until
  * one becomes available, or a timeout of 15 seconds elapses. When the latter
  * happens, -ERESTARTSYS is returned.
  *
  * Can only be called from process context (for now).
  *
  * Return: 0 on success and an appropriate error value on failure.
  */
 int rpmsg_send(struct rpmsg_endpoint *ept, void *data, int len)
 {
 	if (WARN_ON(!ept))
 		return -EINVAL;
 	if (!ept->ops->send)
 		return -ENXIO;

 	return ept->ops->send(ept, data, len);
 }
 EXPORT_SYMBOL(rpmsg_send);

 /**
  * rpmsg_sendto() - send a message across to the remote processor, specify dst
  * @ept: the rpmsg endpoint
  * @data: payload of message
  * @len: length of payload
  * @dst: destination address
  *
  * This function sends @data of length @len to the remote @dst address.
  * The message will be sent to the remote processor which the @ept
  * endpoint belongs to, using @ept's address as source.
  * In case there are no TX buffers available, the function will block until
  * one becomes available, or a timeout of 15 seconds elapses. When the latter
  * happens, -ERESTARTSYS is returned.
  *
  * Can only be called from process context (for now).
  *
  * Return: 0 on success and an appropriate error value on failure.
  */
 int rpmsg_sendto(struct rpmsg_endpoint *ept, void *data, int len, u32 dst)
 {
 	if (WARN_ON(!ept))
 		return -EINVAL;
 	if (!ept->ops->sendto)
 		return -ENXIO;

 	return ept->ops->sendto(ept, data, len, dst);
 }
 EXPORT_SYMBOL(rpmsg_sendto);

 /**
  * rpmsg_send_offchannel() - send a message using explicit src/dst addresses
  * @ept: the rpmsg endpoint
  * @src: source address
  * @dst: destination address
  * @data: payload of message
  * @len: length of payload
  *
  * This function sends @data of length @len to the remote @dst address,
  * and uses @src as the source address.
  * The message will be sent to the remote processor which the @ept
  * endpoint belongs to.
  * In case there are no TX buffers available, the function will block until
  * one becomes available, or a timeout of 15 seconds elapses. When the latter
  * happens, -ERESTARTSYS is returned.
  *
  * Can only be called from process context (for now).
  *
  * Return: 0 on success and an appropriate error value on failure.
  */
 int rpmsg_send_offchannel(struct rpmsg_endpoint *ept, u32 src, u32 dst,
 			  void *data, int len)
 {
 	if (WARN_ON(!ept))
 		return -EINVAL;
 	if (!ept->ops->send_offchannel)
 		return -ENXIO;

 	return ept->ops->send_offchannel(ept, src, dst, data, len);
 }
 EXPORT_SYMBOL(rpmsg_send_offchannel);

 /**
  * rpmsg_trysend() - send a message across to the remote processor
  * @ept: the rpmsg endpoint
  * @data: payload of message
  * @len: length of payload
  *
  * This function sends @data of length @len on the @ept endpoint.
  * The message will be sent to the remote processor which the @ept
  * endpoint belongs to, using @ept's address as source and its associated
  * rpdev's address as destination.
  * In case there are no TX buffers available, the function will immediately
  * return -ENOMEM without waiting until one becomes available.
  *
  * Can only be called from process context (for now).
  *
  * Return: 0 on success and an appropriate error value on failure.
  */
 int rpmsg_trysend(struct rpmsg_endpoint *ept, void *data, int len)
 {
 	if (WARN_ON(!ept))
 		return -EINVAL;
 	if (!ept->ops->trysend)
 		return -ENXIO;

 	return ept->ops->trysend(ept, data, len);
 }
 EXPORT_SYMBOL(rpmsg_trysend);

 /**
  * rpmsg_trysendto() - send a message across to the remote processor, specify dst
  * @ept: the rpmsg endpoint
  * @data: payload of message
  * @len: length of payload
  * @dst: destination address
  *
  * This function sends @data of length @len to the remote @dst address.
  * The message will be sent to the remote processor which the @ept
  * endpoint belongs to, using @ept's address as source.
  * In case there are no TX buffers available, the function will immediately
  * return -ENOMEM without waiting until one becomes available.
  *
  * Can only be called from process context (for now).
  *
  * Return: 0 on success and an appropriate error value on failure.
  */
 int rpmsg_trysendto(struct rpmsg_endpoint *ept, void *data, int len, u32 dst)
 {
 	if (WARN_ON(!ept))
 		return -EINVAL;
 	if (!ept->ops->trysendto)
 		return -ENXIO;

 	return ept->ops->trysendto(ept, data, len, dst);
 }
 EXPORT_SYMBOL(rpmsg_trysendto);

 /**
  * rpmsg_poll() - poll the endpoint's send buffers
  * @ept:	the rpmsg endpoint
  * @filp:	file for poll_wait()
  * @wait:	poll_table for poll_wait()
  *
  * Return: mask representing the current state of the endpoint's send buffers
  */
 __poll_t rpmsg_poll(struct rpmsg_endpoint *ept, struct file *filp,
 			poll_table *wait)
 {
 	if (WARN_ON(!ept))
 		return 0;
 	if (!ept->ops->poll)
 		return 0;

 	return ept->ops->poll(ept, filp, wait);
 }
 EXPORT_SYMBOL(rpmsg_poll);

 /**
  * rpmsg_trysend_offchannel() - send a message using explicit src/dst addresses
  * @ept: the rpmsg endpoint
  * @src: source address
  * @dst: destination address
  * @data: payload of message
  * @len: length of payload
  *
  * This function sends @data of length @len to the remote @dst address,
  * and uses @src as the source address.
  * The message will be sent to the remote processor which the @ept
  * endpoint belongs to.
  * In case there are no TX buffers available, the function will immediately
  * return -ENOMEM without waiting until one becomes available.
  *
  * Can only be called from process context (for now).
  *
  * Return: 0 on success and an appropriate error value on failure.
  */
 int rpmsg_trysend_offchannel(struct rpmsg_endpoint *ept, u32 src, u32 dst,
 			     void *data, int len)
 {
 	if (WARN_ON(!ept))
 		return -EINVAL;
 	if (!ept->ops->trysend_offchannel)
 		return -ENXIO;

 	return ept->ops->trysend_offchannel(ept, src, dst, data, len);
 }
 EXPORT_SYMBOL(rpmsg_trysend_offchannel);

 /**
  * rpmsg_set_flow_control() - request remote to pause/resume transmission
  * @ept:	the rpmsg endpoint
  * @pause:	pause transmission
  * @dst:	destination address of the endpoint
  *
  * Return: 0 on success and an appropriate error value on failure.
  */
 int rpmsg_set_flow_control(struct rpmsg_endpoint *ept, bool pause, u32 dst)
 {
 	if (WARN_ON(!ept))
 		return -EINVAL;
 	if (!ept->ops->set_flow_control)
 		return -EOPNOTSUPP;

 	return ept->ops->set_flow_control(ept, pause, dst);
 }
 EXPORT_SYMBOL_GPL(rpmsg_set_flow_control);

 /**
  * rpmsg_get_mtu() - get maximum transmission buffer size for sending message.
  * @ept: the rpmsg endpoint
  *
  * This function returns maximum buffer size available for a single outgoing message.
  *
  * Return: the maximum transmission size on success and an appropriate error
  * value on failure.
  */

 ssize_t rpmsg_get_mtu(struct rpmsg_endpoint *ept)
 {
 	if (WARN_ON(!ept))
 		return -EINVAL;
 	if (!ept->ops->get_mtu)
 		return -ENOTSUPP;

 	return ept->ops->get_mtu(ept);
 }
 EXPORT_SYMBOL(rpmsg_get_mtu);

 /*
  * match a rpmsg channel with a channel info struct.
  * this is used to make sure we're not creating rpmsg devices for channels
  * that already exist.
  */
 static int rpmsg_device_match(struct device *dev, const void *data)
 {
 	const struct rpmsg_channel_info *chinfo = data;
 	struct rpmsg_device *rpdev = to_rpmsg_device(dev);

 	if (chinfo->src != RPMSG_ADDR_ANY && chinfo->src != rpdev->src)
 		return 0;

 	if (chinfo->dst != RPMSG_ADDR_ANY && chinfo->dst != rpdev->dst)
 		return 0;

 	if (strncmp(chinfo->name, rpdev->id.name, RPMSG_NAME_SIZE))
 		return 0;

 	/* found a match ! */
 	return 1;
 }

 struct device *rpmsg_find_device(struct device *parent,
 				 struct rpmsg_channel_info *chinfo)
 {
 	return device_find_child(parent, chinfo, rpmsg_device_match);

 }
 EXPORT_SYMBOL(rpmsg_find_device);

 /* sysfs show configuration fields */
 #define rpmsg_show_attr(field, path, format_string)			\
 static ssize_t								\
 field##_show(struct device *dev,					\
 			struct device_attribute *attr, char *buf)	\
 {									\
 	struct rpmsg_device *rpdev = to_rpmsg_device(dev);		\
 									\
 	return sprintf(buf, format_string, rpdev->path);		\
 }									\
 static DEVICE_ATTR_RO(field);

 #define rpmsg_string_attr(field, member)				\
 static ssize_t								\
 field##_store(struct device *dev, struct device_attribute *attr,	\
 	      const char *buf, size_t sz)				\
 {									\
 	struct rpmsg_device *rpdev = to_rpmsg_device(dev);		\
 	const char *old;						\
 	char *new;							\
 									\
 	new = kstrndup(buf, sz, GFP_KERNEL);				\
 	if (!new)							\
 		return -ENOMEM;						\
 	new[strcspn(new, "\n")] = '\0';					\
 									\
 	device_lock(dev);						\
 	old = rpdev->member;						\
 	if (strlen(new)) {						\
 		rpdev->member = new;					\
 	} else {							\
 		kfree(new);						\
 		rpdev->member = NULL;					\
 	}								\
 	device_unlock(dev);						\
 									\
 	kfree(old);							\
 									\
 	return sz;							\
 }									\
 static ssize_t								\
 field##_show(struct device *dev,					\
 	     struct device_attribute *attr, char *buf)			\
 {									\
 	struct rpmsg_device *rpdev = to_rpmsg_device(dev);		\
 									\
 	return sprintf(buf, "%s\n", rpdev->member);			\
 }									\
 static DEVICE_ATTR_RW(field)

 /* for more info, see Documentation/ABI/testing/sysfs-bus-rpmsg */
 rpmsg_show_attr(name, id.name, "%s\n");
 rpmsg_show_attr(src, src, "0x%x\n");
 rpmsg_show_attr(dst, dst, "0x%x\n");
 rpmsg_show_attr(announce, announce ? "true" : "false", "%s\n");
 rpmsg_string_attr(driver_override, driver_override);

 static ssize_t modalias_show(struct device *dev,
 			     struct device_attribute *attr, char *buf)
 {
 	struct rpmsg_device *rpdev = to_rpmsg_device(dev);
 	ssize_t len;

 	len = of_device_modalias(dev, buf, PAGE_SIZE);
 	if (len != -ENODEV)
 		return len;

 	return sprintf(buf, RPMSG_DEVICE_MODALIAS_FMT "\n", rpdev->id.name);
 }
 static DEVICE_ATTR_RO(modalias);

 static struct attribute *rpmsg_dev_attrs[] = {
 	&dev_attr_name.attr,
 	&dev_attr_modalias.attr,
 	&dev_attr_dst.attr,
 	&dev_attr_src.attr,
 	&dev_attr_announce.attr,
 	&dev_attr_driver_override.attr,
 	NULL,
 };
 ATTRIBUTE_GROUPS(rpmsg_dev);

 /* rpmsg devices and drivers are matched using the service name */
 static inline int rpmsg_id_match(const struct rpmsg_device *rpdev,
 				  const struct rpmsg_device_id *id)
 {
 	return strncmp(id->name, rpdev->id.name, RPMSG_NAME_SIZE) == 0;
 }

 /* match rpmsg channel and rpmsg driver */
 static int rpmsg_dev_match(struct device *dev, const struct device_driver *drv)
 {
 	struct rpmsg_device *rpdev = to_rpmsg_device(dev);
 	const struct rpmsg_driver *rpdrv = to_rpmsg_driver(drv);
 	const struct rpmsg_device_id *ids = rpdrv->id_table;
 	unsigned int i;

 	if (rpdev->driver_override)
 		return !strcmp(rpdev->driver_override, drv->name);

 	if (ids)
 		for (i = 0; ids[i].name[0]; i++)
 			if (rpmsg_id_match(rpdev, &ids[i])) {
 				rpdev->id.driver_data = ids[i].driver_data;
 				return 1;
 			}

 	return of_driver_match_device(dev, drv);
 }

 static int rpmsg_uevent(const struct device *dev, struct kobj_uevent_env *env)
 {
 	const struct rpmsg_device *rpdev = to_rpmsg_device(dev);
 	int ret;

 	ret = of_device_uevent_modalias(dev, env);
 	if (ret != -ENODEV)
 		return ret;

 	return add_uevent_var(env, "MODALIAS=" RPMSG_DEVICE_MODALIAS_FMT,
 					rpdev->id.name);
 }

 /*
  * when an rpmsg driver is probed with a channel, we seamlessly create
  * it an endpoint, binding its rx callback to a unique local rpmsg
  * address.
  *
  * if we need to, we also announce about this channel to the remote
  * processor (needed in case the driver is exposing an rpmsg service).
  */
 static int rpmsg_dev_probe(struct device *dev)
 {
 	struct rpmsg_device *rpdev = to_rpmsg_device(dev);
 	struct rpmsg_driver *rpdrv = to_rpmsg_driver(rpdev->dev.driver);
 	struct rpmsg_channel_info chinfo = {};
 	struct rpmsg_endpoint *ept = NULL;
 	int err;

 	err = dev_pm_domain_attach(dev, true);
 	if (err)
 		goto out;

 	if (rpdrv->callback) {
 		strscpy(chinfo.name, rpdev->id.name, sizeof(chinfo.name));
 		chinfo.src = rpdev->src;
 		chinfo.dst = RPMSG_ADDR_ANY;

 		ept = rpmsg_create_ept(rpdev, rpdrv->callback, NULL, chinfo);
 		if (!ept) {
 			dev_err(dev, "failed to create endpoint\n");
 			err = -ENOMEM;
 			goto out;
 		}

 		rpdev->ept = ept;
 		rpdev->src = ept->addr;

 		ept->flow_cb = rpdrv->flowcontrol;
 	}

 	err = rpdrv->probe(rpdev);
 	if (err) {
 		dev_err(dev, "%s: failed: %d\n", __func__, err);
 		goto destroy_ept;
 	}

 	if (ept && rpdev->ops->announce_create) {
 		err = rpdev->ops->announce_create(rpdev);
 		if (err) {
 			dev_err(dev, "failed to announce creation\n");
 			goto remove_rpdev;
 		}
 	}

 	return 0;

 remove_rpdev:
 	if (rpdrv->remove)
 		rpdrv->remove(rpdev);
 destroy_ept:
 	if (ept)
 		rpmsg_destroy_ept(ept);
 out:
 	return err;
 }

 static void rpmsg_dev_remove(struct device *dev)
 {
 	struct rpmsg_device *rpdev = to_rpmsg_device(dev);
 	struct rpmsg_driver *rpdrv = to_rpmsg_driver(rpdev->dev.driver);

 	if (rpdev->ops->announce_destroy)
 		rpdev->ops->announce_destroy(rpdev);

 	if (rpdrv->remove)
 		rpdrv->remove(rpdev);

 	dev_pm_domain_detach(dev, true);

 	if (rpdev->ept)
 		rpmsg_destroy_ept(rpdev->ept);
 }

 static const struct bus_type rpmsg_bus = {
 	.name		= "rpmsg",
 	.match		= rpmsg_dev_match,
 	.dev_groups	= rpmsg_dev_groups,
 	.uevent		= rpmsg_uevent,
 	.probe		= rpmsg_dev_probe,
 	.remove		= rpmsg_dev_remove,
 };

 /*
  * A helper for registering rpmsg device with driver override and name.
  * Drivers should not be using it, but instead rpmsg_register_device().
  */
 int rpmsg_register_device_override(struct rpmsg_device *rpdev,
 				   const char *driver_override)
 {
 	struct device *dev = &rpdev->dev;
 	int ret;

 	if (driver_override)
 		strscpy_pad(rpdev->id.name, driver_override, RPMSG_NAME_SIZE);

 	dev_set_name(dev, "%s.%s.%d.%d", dev_name(dev->parent),
 		     rpdev->id.name, rpdev->src, rpdev->dst);

 	dev->bus = &rpmsg_bus;

 	device_initialize(dev);
 	if (driver_override) {
 		ret = driver_set_override(dev, &rpdev->driver_override,
 					  driver_override,
 					  strlen(driver_override));
 		if (ret) {
 			dev_err(dev, "device_set_override failed: %d\n", ret);
 			put_device(dev);
 			return ret;
 		}
 	}

 	ret = device_add(dev);
 	if (ret) {
 		dev_err(dev, "device_add failed: %d\n", ret);
 		kfree(rpdev->driver_override);
 		rpdev->driver_override = NULL;
 		put_device(dev);
 	}

 	return ret;
 }
 EXPORT_SYMBOL(rpmsg_register_device_override);

 int rpmsg_register_device(struct rpmsg_device *rpdev)
 {
 	return rpmsg_register_device_override(rpdev, NULL);
 }
 EXPORT_SYMBOL(rpmsg_register_device);

 /*
  * find an existing channel using its name + address properties,
  * and destroy it
  */
 int rpmsg_unregister_device(struct device *parent,
 			    struct rpmsg_channel_info *chinfo)
 {
 	struct device *dev;

 	dev = rpmsg_find_device(parent, chinfo);
 	if (!dev)
 		return -EINVAL;

 	device_unregister(dev);

 	put_device(dev);

 	return 0;
 }
 EXPORT_SYMBOL(rpmsg_unregister_device);

 /**
  * __register_rpmsg_driver() - register an rpmsg driver with the rpmsg bus
  * @rpdrv: pointer to a struct rpmsg_driver
  * @owner: owning module/driver
  *
  * Return: 0 on success, and an appropriate error value on failure.
  */
 int __register_rpmsg_driver(struct rpmsg_driver *rpdrv, struct module *owner)
 {
 	rpdrv->drv.bus = &rpmsg_bus;
 	rpdrv->drv.owner = owner;
 	return driver_register(&rpdrv->drv);
 }
 EXPORT_SYMBOL(__register_rpmsg_driver);

 /**
  * unregister_rpmsg_driver() - unregister an rpmsg driver from the rpmsg bus
  * @rpdrv: pointer to a struct rpmsg_driver
  *
  * Return: 0 on success, and an appropriate error value on failure.
  */
 void unregister_rpmsg_driver(struct rpmsg_driver *rpdrv)
 {
 	driver_unregister(&rpdrv->drv);
 }
 EXPORT_SYMBOL(unregister_rpmsg_driver);


 static int __init rpmsg_init(void)
 {
 	int ret;

 	ret = class_register(&rpmsg_class);
 	if (ret) {
 		pr_err("failed to register rpmsg class\n");
 		return ret;
 	}

 	ret = bus_register(&rpmsg_bus);
 	if (ret) {
 		pr_err("failed to register rpmsg bus: %d\n", ret);
 		class_destroy(&rpmsg_class);
 	}
 	return ret;
 }
 postcore_initcall(rpmsg_init);

 static void __exit rpmsg_fini(void)
 {
 	bus_unregister(&rpmsg_bus);
 	class_destroy(&rpmsg_class);
 }
 module_exit(rpmsg_fini);

 MODULE_DESCRIPTION("remote processor messaging bus");
 MODULE_LICENSE("GPL v2");
	// SPDX-License-Identifier: GPL-2.0
	/*
	* remote processor messaging bus
	*
	* Copyright (C) 2011 Texas Instruments, Inc.
	* Copyright (C) 2011 Google, Inc.
	*
	* Ohad Ben-Cohen <[email protected]>
	* Brian Swetland <[email protected]>
	*/

	#define pr_fmt(fmt) "%s: " fmt, __func__

	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/rpmsg.h>
	#include <linux/of_device.h>
	#include <linux/pm_domain.h>
	#include <linux/slab.h>

	#include "rpmsg_internal.h"

	const struct class rpmsg_class = {
	.name = "rpmsg",
	};
	EXPORT_SYMBOL(rpmsg_class);

	/**
	* rpmsg_create_channel() - create a new rpmsg channel
	* using its name and address info.
	* @rpdev: rpmsg device
	* @chinfo: channel_info to bind
	*
	* Return: a pointer to the new rpmsg device on success, or NULL on error.
	*/
	struct rpmsg_device rpmsg_create_channel(struct rpmsg_device rpdev,
	struct rpmsg_channel_info *chinfo)
	{
	if (WARN_ON(!rpdev))
	return NULL;
	if (!rpdev->ops \|\| !rpdev->ops->create_channel) {
	dev_err(&rpdev->dev, "no create_channel ops found\n");
	return NULL;
	}

	return rpdev->ops->create_channel(rpdev, chinfo);
	}
	EXPORT_SYMBOL(rpmsg_create_channel);

	/**
	* rpmsg_release_channel() - release a rpmsg channel
	* using its name and address info.
	* @rpdev: rpmsg device
	* @chinfo: channel_info to bind
	*
	* Return: 0 on success or an appropriate error value.
	*/
	int rpmsg_release_channel(struct rpmsg_device *rpdev,
	struct rpmsg_channel_info *chinfo)
	{
	if (WARN_ON(!rpdev))
	return -EINVAL;
	if (!rpdev->ops \|\| !rpdev->ops->release_channel) {
	dev_err(&rpdev->dev, "no release_channel ops found\n");
	return -ENXIO;
	}

	return rpdev->ops->release_channel(rpdev, chinfo);
	}
	EXPORT_SYMBOL(rpmsg_release_channel);

	/**
	* rpmsg_create_ept() - create a new rpmsg_endpoint
	* @rpdev: rpmsg channel device
	* @cb: rx callback handler
	* @priv: private data for the driver's use
	* @chinfo: channel_info with the local rpmsg address to bind with @cb
	*
	* Every rpmsg address in the system is bound to an rx callback (so when
	* inbound messages arrive, they are dispatched by the rpmsg bus using the
	* appropriate callback handler) by means of an rpmsg_endpoint struct.
	*
	* This function allows drivers to create such an endpoint, and by that,
	* bind a callback, and possibly some private data too, to an rpmsg address
	* (either one that is known in advance, or one that will be dynamically
	* assigned for them).
	*
	* Simple rpmsg drivers need not call rpmsg_create_ept, because an endpoint
	* is already created for them when they are probed by the rpmsg bus
	* (using the rx callback provided when they registered to the rpmsg bus).
	*
	* So things should just work for simple drivers: they already have an
	* endpoint, their rx callback is bound to their rpmsg address, and when
	* relevant inbound messages arrive (i.e. messages which their dst address
	* equals to the src address of their rpmsg channel), the driver's handler
	* is invoked to process it.
	*
	* That said, more complicated drivers might need to allocate
	* additional rpmsg addresses, and bind them to different rx callbacks.
	* To accomplish that, those drivers need to call this function.
	*
	* Drivers should provide their @rpdev channel (so the new endpoint would belong
	* to the same remote processor their channel belongs to), an rx callback
	* function, an optional private data (which is provided back when the
	* rx callback is invoked), and an address they want to bind with the
	* callback. If @addr is RPMSG_ADDR_ANY, then rpmsg_create_ept will
	* dynamically assign them an available rpmsg address (drivers should have
	* a very good reason why not to always use RPMSG_ADDR_ANY here).
	*
	* Return: a pointer to the endpoint on success, or NULL on error.
	*/
	struct rpmsg_endpoint rpmsg_create_ept(struct rpmsg_device rpdev,
	rpmsg_rx_cb_t cb, void *priv,
	struct rpmsg_channel_info chinfo)
	{
	if (WARN_ON(!rpdev))
	return NULL;

	return rpdev->ops->create_ept(rpdev, cb, priv, chinfo);
	}
	EXPORT_SYMBOL(rpmsg_create_ept);

	/**
	* rpmsg_destroy_ept() - destroy an existing rpmsg endpoint
	* @ept: endpoing to destroy
	*
	* Should be used by drivers to destroy an rpmsg endpoint previously
	* created with rpmsg_create_ept(). As with other types of "free" NULL
	* is a valid parameter.
	*/
	void rpmsg_destroy_ept(struct rpmsg_endpoint *ept)
	{
	if (ept && ept->ops)
	ept->ops->destroy_ept(ept);
	}
	EXPORT_SYMBOL(rpmsg_destroy_ept);

	/**
	* rpmsg_send() - send a message across to the remote processor
	* @ept: the rpmsg endpoint
	* @data: payload of message
	* @len: length of payload
	*
	* This function sends @data of length @len on the @ept endpoint.
	* The message will be sent to the remote processor which the @ept
	* endpoint belongs to, using @ept's address and its associated rpmsg
	* device destination addresses.
	* In case there are no TX buffers available, the function will block until
	* one becomes available, or a timeout of 15 seconds elapses. When the latter
	* happens, -ERESTARTSYS is returned.
	*
	* Can only be called from process context (for now).
	*
	* Return: 0 on success and an appropriate error value on failure.
	*/
	int rpmsg_send(struct rpmsg_endpoint ept, void data, int len)
	{
	if (WARN_ON(!ept))
	return -EINVAL;
	if (!ept->ops->send)
	return -ENXIO;

	return ept->ops->send(ept, data, len);
	}
	EXPORT_SYMBOL(rpmsg_send);

	/**
	* rpmsg_sendto() - send a message across to the remote processor, specify dst
	* @ept: the rpmsg endpoint
	* @data: payload of message
	* @len: length of payload
	* @dst: destination address
	*
	* This function sends @data of length @len to the remote @dst address.
	* The message will be sent to the remote processor which the @ept
	* endpoint belongs to, using @ept's address as source.
	* In case there are no TX buffers available, the function will block until
	* one becomes available, or a timeout of 15 seconds elapses. When the latter
	* happens, -ERESTARTSYS is returned.
	*
	* Can only be called from process context (for now).
	*
	* Return: 0 on success and an appropriate error value on failure.
	*/
	int rpmsg_sendto(struct rpmsg_endpoint ept, void data, int len, u32 dst)
	{
	if (WARN_ON(!ept))
	return -EINVAL;
	if (!ept->ops->sendto)
	return -ENXIO;

	return ept->ops->sendto(ept, data, len, dst);
	}
	EXPORT_SYMBOL(rpmsg_sendto);

	/**
	* rpmsg_send_offchannel() - send a message using explicit src/dst addresses
	* @ept: the rpmsg endpoint
	* @src: source address
	* @dst: destination address
	* @data: payload of message
	* @len: length of payload
	*
	* This function sends @data of length @len to the remote @dst address,
	* and uses @src as the source address.
	* The message will be sent to the remote processor which the @ept
	* endpoint belongs to.
	* In case there are no TX buffers available, the function will block until
	* one becomes available, or a timeout of 15 seconds elapses. When the latter
	* happens, -ERESTARTSYS is returned.
	*
	* Can only be called from process context (for now).
	*
	* Return: 0 on success and an appropriate error value on failure.
	*/
	int rpmsg_send_offchannel(struct rpmsg_endpoint *ept, u32 src, u32 dst,
	void *data, int len)
	{
	if (WARN_ON(!ept))
	return -EINVAL;
	if (!ept->ops->send_offchannel)
	return -ENXIO;

	return ept->ops->send_offchannel(ept, src, dst, data, len);
	}
	EXPORT_SYMBOL(rpmsg_send_offchannel);

	/**
	* rpmsg_trysend() - send a message across to the remote processor
	* @ept: the rpmsg endpoint
	* @data: payload of message
	* @len: length of payload
	*
	* This function sends @data of length @len on the @ept endpoint.
	* The message will be sent to the remote processor which the @ept
	* endpoint belongs to, using @ept's address as source and its associated
	* rpdev's address as destination.
	* In case there are no TX buffers available, the function will immediately
	* return -ENOMEM without waiting until one becomes available.
	*
	* Can only be called from process context (for now).
	*
	* Return: 0 on success and an appropriate error value on failure.
	*/
	int rpmsg_trysend(struct rpmsg_endpoint ept, void data, int len)
	{
	if (WARN_ON(!ept))
	return -EINVAL;
	if (!ept->ops->trysend)
	return -ENXIO;

	return ept->ops->trysend(ept, data, len);
	}
	EXPORT_SYMBOL(rpmsg_trysend);

	/**
	* rpmsg_trysendto() - send a message across to the remote processor, specify dst
	* @ept: the rpmsg endpoint
	* @data: payload of message
	* @len: length of payload
	* @dst: destination address
	*
	* This function sends @data of length @len to the remote @dst address.
	* The message will be sent to the remote processor which the @ept
	* endpoint belongs to, using @ept's address as source.
	* In case there are no TX buffers available, the function will immediately
	* return -ENOMEM without waiting until one becomes available.
	*
	* Can only be called from process context (for now).
	*
	* Return: 0 on success and an appropriate error value on failure.
	*/
	int rpmsg_trysendto(struct rpmsg_endpoint ept, void data, int len, u32 dst)
	{
	if (WARN_ON(!ept))
	return -EINVAL;
	if (!ept->ops->trysendto)
	return -ENXIO;

	return ept->ops->trysendto(ept, data, len, dst);
	}
	EXPORT_SYMBOL(rpmsg_trysendto);

	/**
	* rpmsg_poll() - poll the endpoint's send buffers
	* @ept: the rpmsg endpoint
	* @filp: file for poll_wait()
	* @wait: poll_table for poll_wait()
	*
	* Return: mask representing the current state of the endpoint's send buffers
	*/
	__poll_t rpmsg_poll(struct rpmsg_endpoint ept, struct file filp,
	poll_table *wait)
	{
	if (WARN_ON(!ept))
	return 0;
	if (!ept->ops->poll)
	return 0;

	return ept->ops->poll(ept, filp, wait);
	}
	EXPORT_SYMBOL(rpmsg_poll);

	/**
	* rpmsg_trysend_offchannel() - send a message using explicit src/dst addresses
	* @ept: the rpmsg endpoint
	* @src: source address
	* @dst: destination address
	* @data: payload of message
	* @len: length of payload
	*
	* This function sends @data of length @len to the remote @dst address,
	* and uses @src as the source address.
	* The message will be sent to the remote processor which the @ept
	* endpoint belongs to.
	* In case there are no TX buffers available, the function will immediately
	* return -ENOMEM without waiting until one becomes available.
	*
	* Can only be called from process context (for now).
	*
	* Return: 0 on success and an appropriate error value on failure.
	*/
	int rpmsg_trysend_offchannel(struct rpmsg_endpoint *ept, u32 src, u32 dst,
	void *data, int len)
	{
	if (WARN_ON(!ept))
	return -EINVAL;
	if (!ept->ops->trysend_offchannel)
	return -ENXIO;

	return ept->ops->trysend_offchannel(ept, src, dst, data, len);
	}
	EXPORT_SYMBOL(rpmsg_trysend_offchannel);

	/**
	* rpmsg_set_flow_control() - request remote to pause/resume transmission
	* @ept: the rpmsg endpoint
	* @pause: pause transmission
	* @dst: destination address of the endpoint
	*
	* Return: 0 on success and an appropriate error value on failure.
	*/
	int rpmsg_set_flow_control(struct rpmsg_endpoint *ept, bool pause, u32 dst)
	{
	if (WARN_ON(!ept))
	return -EINVAL;
	if (!ept->ops->set_flow_control)
	return -EOPNOTSUPP;

	return ept->ops->set_flow_control(ept, pause, dst);
	}
	EXPORT_SYMBOL_GPL(rpmsg_set_flow_control);

	/**
	* rpmsg_get_mtu() - get maximum transmission buffer size for sending message.
	* @ept: the rpmsg endpoint
	*
	* This function returns maximum buffer size available for a single outgoing message.
	*
	* Return: the maximum transmission size on success and an appropriate error
	* value on failure.
	*/

	ssize_t rpmsg_get_mtu(struct rpmsg_endpoint *ept)
	{
	if (WARN_ON(!ept))
	return -EINVAL;
	if (!ept->ops->get_mtu)
	return -ENOTSUPP;

	return ept->ops->get_mtu(ept);
	}
	EXPORT_SYMBOL(rpmsg_get_mtu);

	/*
	* match a rpmsg channel with a channel info struct.
	* this is used to make sure we're not creating rpmsg devices for channels
	* that already exist.
	*/
	static int rpmsg_device_match(struct device dev, const void data)
	{
	const struct rpmsg_channel_info *chinfo = data;
	struct rpmsg_device *rpdev = to_rpmsg_device(dev);

	if (chinfo->src != RPMSG_ADDR_ANY && chinfo->src != rpdev->src)
	return 0;

	if (chinfo->dst != RPMSG_ADDR_ANY && chinfo->dst != rpdev->dst)
	return 0;

	if (strncmp(chinfo->name, rpdev->id.name, RPMSG_NAME_SIZE))
	return 0;

	/* found a match ! */
	return 1;
	}

	struct device rpmsg_find_device(struct device parent,
	struct rpmsg_channel_info *chinfo)
	{
	return device_find_child(parent, chinfo, rpmsg_device_match);

	}
	EXPORT_SYMBOL(rpmsg_find_device);

	/* sysfs show configuration fields */
	#define rpmsg_show_attr(field, path, format_string) \
	static ssize_t \
	field##_show(struct device *dev, \
	struct device_attribute attr, char buf) \
	{ \
	struct rpmsg_device *rpdev = to_rpmsg_device(dev); \
	\
	return sprintf(buf, format_string, rpdev->path); \
	} \
	static DEVICE_ATTR_RO(field);

	#define rpmsg_string_attr(field, member) \
	static ssize_t \
	field##_store(struct device dev, struct device_attribute attr, \
	const char *buf, size_t sz) \
	{ \
	struct rpmsg_device *rpdev = to_rpmsg_device(dev); \
	const char *old; \
	char *new; \
	\
	new = kstrndup(buf, sz, GFP_KERNEL); \
	if (!new) \
	return -ENOMEM; \
	new[strcspn(new, "\n")] = '\0'; \
	\
	device_lock(dev); \
	old = rpdev->member; \
	if (strlen(new)) { \
	rpdev->member = new; \
	} else { \
	kfree(new); \
	rpdev->member = NULL; \
	} \
	device_unlock(dev); \
	\
	kfree(old); \
	\
	return sz; \
	} \
	static ssize_t \
	field##_show(struct device *dev, \
	struct device_attribute attr, char buf) \
	{ \
	struct rpmsg_device *rpdev = to_rpmsg_device(dev); \
	\
	return sprintf(buf, "%s\n", rpdev->member); \
	} \
	static DEVICE_ATTR_RW(field)

	/* for more info, see Documentation/ABI/testing/sysfs-bus-rpmsg */
	rpmsg_show_attr(name, id.name, "%s\n");
	rpmsg_show_attr(src, src, "0x%x\n");
	rpmsg_show_attr(dst, dst, "0x%x\n");
	rpmsg_show_attr(announce, announce ? "true" : "false", "%s\n");
	rpmsg_string_attr(driver_override, driver_override);

	static ssize_t modalias_show(struct device *dev,
	struct device_attribute attr, char buf)
	{
	struct rpmsg_device *rpdev = to_rpmsg_device(dev);
	ssize_t len;

	len = of_device_modalias(dev, buf, PAGE_SIZE);
	if (len != -ENODEV)
	return len;

	return sprintf(buf, RPMSG_DEVICE_MODALIAS_FMT "\n", rpdev->id.name);
	}
	static DEVICE_ATTR_RO(modalias);

	static struct attribute *rpmsg_dev_attrs[] = {
	&dev_attr_name.attr,
	&dev_attr_modalias.attr,
	&dev_attr_dst.attr,
	&dev_attr_src.attr,
	&dev_attr_announce.attr,
	&dev_attr_driver_override.attr,
	NULL,
	};
	ATTRIBUTE_GROUPS(rpmsg_dev);

	/* rpmsg devices and drivers are matched using the service name */
	static inline int rpmsg_id_match(const struct rpmsg_device *rpdev,
	const struct rpmsg_device_id *id)
	{
	return strncmp(id->name, rpdev->id.name, RPMSG_NAME_SIZE) == 0;
	}

	/* match rpmsg channel and rpmsg driver */
	static int rpmsg_dev_match(struct device dev, const struct device_driver drv)
	{
	struct rpmsg_device *rpdev = to_rpmsg_device(dev);
	const struct rpmsg_driver *rpdrv = to_rpmsg_driver(drv);
	const struct rpmsg_device_id *ids = rpdrv->id_table;
	unsigned int i;

	if (rpdev->driver_override)
	return !strcmp(rpdev->driver_override, drv->name);

	if (ids)
	for (i = 0; ids[i].name[0]; i++)
	if (rpmsg_id_match(rpdev, &ids[i])) {
	rpdev->id.driver_data = ids[i].driver_data;
	return 1;
	}

	return of_driver_match_device(dev, drv);
	}

	static int rpmsg_uevent(const struct device dev, struct kobj_uevent_env env)
	{
	const struct rpmsg_device *rpdev = to_rpmsg_device(dev);
	int ret;

	ret = of_device_uevent_modalias(dev, env);
	if (ret != -ENODEV)
	return ret;

	return add_uevent_var(env, "MODALIAS=" RPMSG_DEVICE_MODALIAS_FMT,
	rpdev->id.name);
	}

	/*
	* when an rpmsg driver is probed with a channel, we seamlessly create
	* it an endpoint, binding its rx callback to a unique local rpmsg
	* address.
	*
	* if we need to, we also announce about this channel to the remote
	* processor (needed in case the driver is exposing an rpmsg service).
	*/
	static int rpmsg_dev_probe(struct device *dev)
	{
	struct rpmsg_device *rpdev = to_rpmsg_device(dev);
	struct rpmsg_driver *rpdrv = to_rpmsg_driver(rpdev->dev.driver);
	struct rpmsg_channel_info chinfo = {};
	struct rpmsg_endpoint *ept = NULL;
	int err;

	err = dev_pm_domain_attach(dev, true);
	if (err)
	goto out;

	if (rpdrv->callback) {
	strscpy(chinfo.name, rpdev->id.name, sizeof(chinfo.name));
	chinfo.src = rpdev->src;
	chinfo.dst = RPMSG_ADDR_ANY;

	ept = rpmsg_create_ept(rpdev, rpdrv->callback, NULL, chinfo);
	if (!ept) {
	dev_err(dev, "failed to create endpoint\n");
	err = -ENOMEM;
	goto out;
	}

	rpdev->ept = ept;
	rpdev->src = ept->addr;

	ept->flow_cb = rpdrv->flowcontrol;
	}

	err = rpdrv->probe(rpdev);
	if (err) {
	dev_err(dev, "%s: failed: %d\n", __func__, err);
	goto destroy_ept;
	}

	if (ept && rpdev->ops->announce_create) {
	err = rpdev->ops->announce_create(rpdev);
	if (err) {
	dev_err(dev, "failed to announce creation\n");
	goto remove_rpdev;
	}
	}

	return 0;

	remove_rpdev:
	if (rpdrv->remove)
	rpdrv->remove(rpdev);
	destroy_ept:
	if (ept)
	rpmsg_destroy_ept(ept);
	out:
	return err;
	}

	static void rpmsg_dev_remove(struct device *dev)
	{
	struct rpmsg_device *rpdev = to_rpmsg_device(dev);
	struct rpmsg_driver *rpdrv = to_rpmsg_driver(rpdev->dev.driver);

	if (rpdev->ops->announce_destroy)
	rpdev->ops->announce_destroy(rpdev);

	if (rpdrv->remove)
	rpdrv->remove(rpdev);

	dev_pm_domain_detach(dev, true);

	if (rpdev->ept)
	rpmsg_destroy_ept(rpdev->ept);
	}

	static const struct bus_type rpmsg_bus = {
	.name = "rpmsg",
	.match = rpmsg_dev_match,
	.dev_groups = rpmsg_dev_groups,
	.uevent = rpmsg_uevent,
	.probe = rpmsg_dev_probe,
	.remove = rpmsg_dev_remove,
	};

	/*
	* A helper for registering rpmsg device with driver override and name.
	* Drivers should not be using it, but instead rpmsg_register_device().
	*/
	int rpmsg_register_device_override(struct rpmsg_device *rpdev,
	const char *driver_override)
	{
	struct device *dev = &rpdev->dev;
	int ret;

	if (driver_override)
	strscpy_pad(rpdev->id.name, driver_override, RPMSG_NAME_SIZE);

	dev_set_name(dev, "%s.%s.%d.%d", dev_name(dev->parent),
	rpdev->id.name, rpdev->src, rpdev->dst);

	dev->bus = &rpmsg_bus;

	device_initialize(dev);
	if (driver_override) {
	ret = driver_set_override(dev, &rpdev->driver_override,
	driver_override,
	strlen(driver_override));
	if (ret) {
	dev_err(dev, "device_set_override failed: %d\n", ret);
	put_device(dev);
	return ret;
	}
	}

	ret = device_add(dev);
	if (ret) {
	dev_err(dev, "device_add failed: %d\n", ret);
	kfree(rpdev->driver_override);
	rpdev->driver_override = NULL;
	put_device(dev);
	}

	return ret;
	}
	EXPORT_SYMBOL(rpmsg_register_device_override);

	int rpmsg_register_device(struct rpmsg_device *rpdev)
	{
	return rpmsg_register_device_override(rpdev, NULL);
	}
	EXPORT_SYMBOL(rpmsg_register_device);

	/*
	* find an existing channel using its name + address properties,
	* and destroy it
	*/
	int rpmsg_unregister_device(struct device *parent,
	struct rpmsg_channel_info *chinfo)
	{
	struct device *dev;

	dev = rpmsg_find_device(parent, chinfo);
	if (!dev)
	return -EINVAL;

	device_unregister(dev);

	put_device(dev);

	return 0;
	}
	EXPORT_SYMBOL(rpmsg_unregister_device);

	/**
	* __register_rpmsg_driver() - register an rpmsg driver with the rpmsg bus
	* @rpdrv: pointer to a struct rpmsg_driver
	* @owner: owning module/driver
	*
	* Return: 0 on success, and an appropriate error value on failure.
	*/
	int __register_rpmsg_driver(struct rpmsg_driver rpdrv, struct module owner)
	{
	rpdrv->drv.bus = &rpmsg_bus;
	rpdrv->drv.owner = owner;
	return driver_register(&rpdrv->drv);
	}
	EXPORT_SYMBOL(__register_rpmsg_driver);

	/**
	* unregister_rpmsg_driver() - unregister an rpmsg driver from the rpmsg bus
	* @rpdrv: pointer to a struct rpmsg_driver
	*
	* Return: 0 on success, and an appropriate error value on failure.
	*/
	void unregister_rpmsg_driver(struct rpmsg_driver *rpdrv)
	{
	driver_unregister(&rpdrv->drv);
	}
	EXPORT_SYMBOL(unregister_rpmsg_driver);


	static int __init rpmsg_init(void)
	{
	int ret;

	ret = class_register(&rpmsg_class);
	if (ret) {
	pr_err("failed to register rpmsg class\n");
	return ret;
	}

	ret = bus_register(&rpmsg_bus);
	if (ret) {
	pr_err("failed to register rpmsg bus: %d\n", ret);
	class_destroy(&rpmsg_class);
	}
	return ret;
	}
	postcore_initcall(rpmsg_init);

	static void __exit rpmsg_fini(void)
	{
	bus_unregister(&rpmsg_bus);
	class_destroy(&rpmsg_class);
	}
	module_exit(rpmsg_fini);

	MODULE_DESCRIPTION("remote processor messaging bus");
	MODULE_LICENSE("GPL v2");