Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
1// SPDX-License-Identifier: GPL-2.0
2/**
3 * Device connections
4 *
5 * Copyright (C) 2018 Intel Corporation
6 * Author: Heikki Krogerus <heikki.krogerus@linux.intel.com>
7 */
8
9#include <linux/device.h>
10#include <linux/property.h>
11
12static DEFINE_MUTEX(devcon_lock);
13static LIST_HEAD(devcon_list);
14
15typedef void *(*devcon_match_fn_t)(struct device_connection *con, int ep,
16 void *data);
17
18static void *
19fwnode_graph_devcon_match(struct fwnode_handle *fwnode, const char *con_id,
20 void *data, devcon_match_fn_t match)
21{
22 struct device_connection con = { .id = con_id };
23 struct fwnode_handle *ep;
24 void *ret;
25
26 fwnode_graph_for_each_endpoint(fwnode, ep) {
27 con.fwnode = fwnode_graph_get_remote_port_parent(ep);
28 if (!fwnode_device_is_available(con.fwnode))
29 continue;
30
31 ret = match(&con, -1, data);
32 fwnode_handle_put(con.fwnode);
33 if (ret) {
34 fwnode_handle_put(ep);
35 return ret;
36 }
37 }
38 return NULL;
39}
40
41static void *
42fwnode_devcon_match(struct fwnode_handle *fwnode, const char *con_id,
43 void *data, devcon_match_fn_t match)
44{
45 struct device_connection con = { };
46 void *ret;
47 int i;
48
49 for (i = 0; ; i++) {
50 con.fwnode = fwnode_find_reference(fwnode, con_id, i);
51 if (IS_ERR(con.fwnode))
52 break;
53
54 ret = match(&con, -1, data);
55 fwnode_handle_put(con.fwnode);
56 if (ret)
57 return ret;
58 }
59
60 return NULL;
61}
62
63/**
64 * device_connection_find_match - Find physical connection to a device
65 * @dev: Device with the connection
66 * @con_id: Identifier for the connection
67 * @data: Data for the match function
68 * @match: Function to check and convert the connection description
69 *
70 * Find a connection with unique identifier @con_id between @dev and another
71 * device. @match will be used to convert the connection description to data the
72 * caller is expecting to be returned.
73 */
74void *device_connection_find_match(struct device *dev, const char *con_id,
75 void *data, devcon_match_fn_t match)
76{
77 struct fwnode_handle *fwnode = dev_fwnode(dev);
78 const char *devname = dev_name(dev);
79 struct device_connection *con;
80 void *ret = NULL;
81 int ep;
82
83 if (!match)
84 return NULL;
85
86 if (fwnode) {
87 ret = fwnode_graph_devcon_match(fwnode, con_id, data, match);
88 if (ret)
89 return ret;
90
91 ret = fwnode_devcon_match(fwnode, con_id, data, match);
92 if (ret)
93 return ret;
94 }
95
96 mutex_lock(&devcon_lock);
97
98 list_for_each_entry(con, &devcon_list, list) {
99 ep = match_string(con->endpoint, 2, devname);
100 if (ep < 0)
101 continue;
102
103 if (con_id && strcmp(con->id, con_id))
104 continue;
105
106 ret = match(con, !ep, data);
107 if (ret)
108 break;
109 }
110
111 mutex_unlock(&devcon_lock);
112
113 return ret;
114}
115EXPORT_SYMBOL_GPL(device_connection_find_match);
116
117extern struct bus_type platform_bus_type;
118extern struct bus_type pci_bus_type;
119extern struct bus_type i2c_bus_type;
120extern struct bus_type spi_bus_type;
121
122static struct bus_type *generic_match_buses[] = {
123 &platform_bus_type,
124#ifdef CONFIG_PCI
125 &pci_bus_type,
126#endif
127#ifdef CONFIG_I2C
128 &i2c_bus_type,
129#endif
130#ifdef CONFIG_SPI_MASTER
131 &spi_bus_type,
132#endif
133 NULL,
134};
135
136static int device_fwnode_match(struct device *dev, const void *fwnode)
137{
138 return dev_fwnode(dev) == fwnode;
139}
140
141static void *device_connection_fwnode_match(struct device_connection *con)
142{
143 struct bus_type *bus;
144 struct device *dev;
145
146 for (bus = generic_match_buses[0]; bus; bus++) {
147 dev = bus_find_device(bus, NULL, (void *)con->fwnode,
148 device_fwnode_match);
149 if (dev && !strncmp(dev_name(dev), con->id, strlen(con->id)))
150 return dev;
151
152 put_device(dev);
153 }
154 return NULL;
155}
156
157/* This tries to find the device from the most common bus types by name. */
158static void *generic_match(struct device_connection *con, int ep, void *data)
159{
160 struct bus_type *bus;
161 struct device *dev;
162
163 if (con->fwnode)
164 return device_connection_fwnode_match(con);
165
166 for (bus = generic_match_buses[0]; bus; bus++) {
167 dev = bus_find_device_by_name(bus, NULL, con->endpoint[ep]);
168 if (dev)
169 return dev;
170 }
171
172 /*
173 * We only get called if a connection was found, tell the caller to
174 * wait for the other device to show up.
175 */
176 return ERR_PTR(-EPROBE_DEFER);
177}
178
179/**
180 * device_connection_find - Find two devices connected together
181 * @dev: Device with the connection
182 * @con_id: Identifier for the connection
183 *
184 * Find a connection with unique identifier @con_id between @dev and
185 * another device. On success returns handle to the device that is connected
186 * to @dev, with the reference count for the found device incremented. Returns
187 * NULL if no matching connection was found, or ERR_PTR(-EPROBE_DEFER) when a
188 * connection was found but the other device has not been enumerated yet.
189 */
190struct device *device_connection_find(struct device *dev, const char *con_id)
191{
192 return device_connection_find_match(dev, con_id, NULL, generic_match);
193}
194EXPORT_SYMBOL_GPL(device_connection_find);
195
196/**
197 * device_connection_add - Register a connection description
198 * @con: The connection description to be registered
199 */
200void device_connection_add(struct device_connection *con)
201{
202 mutex_lock(&devcon_lock);
203 list_add_tail(&con->list, &devcon_list);
204 mutex_unlock(&devcon_lock);
205}
206EXPORT_SYMBOL_GPL(device_connection_add);
207
208/**
209 * device_connections_remove - Unregister connection description
210 * @con: The connection description to be unregistered
211 */
212void device_connection_remove(struct device_connection *con)
213{
214 mutex_lock(&devcon_lock);
215 list_del(&con->list);
216 mutex_unlock(&devcon_lock);
217}
218EXPORT_SYMBOL_GPL(device_connection_remove);