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