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// SPDX-License-Identifier: GPL-2.0
/**
* Device connections
*
* Copyright (C) 2018 Intel Corporation
* Author: Heikki Krogerus <heikki.krogerus@linux.intel.com>
*/
#include <linux/device.h>
static DEFINE_MUTEX(devcon_lock);
static LIST_HEAD(devcon_list);
/**
* device_connection_find_match - Find physical connection to a device
* @dev: Device with the connection
* @con_id: Identifier for the connection
* @data: Data for the match function
* @match: Function to check and convert the connection description
*
* Find a connection with unique identifier @con_id between @dev and another
* device. @match will be used to convert the connection description to data the
* caller is expecting to be returned.
*/
void *device_connection_find_match(struct device *dev, const char *con_id,
void *data,
void *(*match)(struct device_connection *con,
int ep, void *data))
{
const char *devname = dev_name(dev);
struct device_connection *con;
void *ret = NULL;
int ep;
if (!match)
return NULL;
mutex_lock(&devcon_lock);
list_for_each_entry(con, &devcon_list, list) {
ep = match_string(con->endpoint, 2, devname);
if (ep < 0)
continue;
if (con_id && strcmp(con->id, con_id))
continue;
ret = match(con, !ep, data);
if (ret)
break;
}
mutex_unlock(&devcon_lock);
return ret;
}
EXPORT_SYMBOL_GPL(device_connection_find_match);
extern struct bus_type platform_bus_type;
extern struct bus_type pci_bus_type;
extern struct bus_type i2c_bus_type;
extern struct bus_type spi_bus_type;
static struct bus_type *generic_match_buses[] = {
&platform_bus_type,
#ifdef CONFIG_PCI
&pci_bus_type,
#endif
#ifdef CONFIG_I2C
&i2c_bus_type,
#endif
#ifdef CONFIG_SPI_MASTER
&spi_bus_type,
#endif
NULL,
};
/* This tries to find the device from the most common bus types by name. */
static void *generic_match(struct device_connection *con, int ep, void *data)
{
struct bus_type *bus;
struct device *dev;
for (bus = generic_match_buses[0]; bus; bus++) {
dev = bus_find_device_by_name(bus, NULL, con->endpoint[ep]);
if (dev)
return dev;
}
/*
* We only get called if a connection was found, tell the caller to
* wait for the other device to show up.
*/
return ERR_PTR(-EPROBE_DEFER);
}
/**
* device_connection_find - Find two devices connected together
* @dev: Device with the connection
* @con_id: Identifier for the connection
*
* Find a connection with unique identifier @con_id between @dev and
* another device. On success returns handle to the device that is connected
* to @dev, with the reference count for the found device incremented. Returns
* NULL if no matching connection was found, or ERR_PTR(-EPROBE_DEFER) when a
* connection was found but the other device has not been enumerated yet.
*/
struct device *device_connection_find(struct device *dev, const char *con_id)
{
return device_connection_find_match(dev, con_id, NULL, generic_match);
}
EXPORT_SYMBOL_GPL(device_connection_find);
/**
* device_connection_add - Register a connection description
* @con: The connection description to be registered
*/
void device_connection_add(struct device_connection *con)
{
mutex_lock(&devcon_lock);
list_add_tail(&con->list, &devcon_list);
mutex_unlock(&devcon_lock);
}
EXPORT_SYMBOL_GPL(device_connection_add);
/**
* device_connections_remove - Unregister connection description
* @con: The connection description to be unregistered
*/
void device_connection_remove(struct device_connection *con)
{
mutex_lock(&devcon_lock);
list_del(&con->list);
mutex_unlock(&devcon_lock);
}
EXPORT_SYMBOL_GPL(device_connection_remove);
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