xref: /openbmc/linux/drivers/base/auxiliary.c (revision ee7da21a)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright (c) 2019-2020 Intel Corporation
4  *
5  * Please see Documentation/driver-api/auxiliary_bus.rst for more information.
6  */
7 
8 #define pr_fmt(fmt) "%s:%s: " fmt, KBUILD_MODNAME, __func__
9 
10 #include <linux/device.h>
11 #include <linux/init.h>
12 #include <linux/slab.h>
13 #include <linux/module.h>
14 #include <linux/pm_domain.h>
15 #include <linux/pm_runtime.h>
16 #include <linux/string.h>
17 #include <linux/auxiliary_bus.h>
18 #include "base.h"
19 
20 static const struct auxiliary_device_id *auxiliary_match_id(const struct auxiliary_device_id *id,
21 							    const struct auxiliary_device *auxdev)
22 {
23 	for (; id->name[0]; id++) {
24 		const char *p = strrchr(dev_name(&auxdev->dev), '.');
25 		int match_size;
26 
27 		if (!p)
28 			continue;
29 		match_size = p - dev_name(&auxdev->dev);
30 
31 		/* use dev_name(&auxdev->dev) prefix before last '.' char to match to */
32 		if (strlen(id->name) == match_size &&
33 		    !strncmp(dev_name(&auxdev->dev), id->name, match_size))
34 			return id;
35 	}
36 	return NULL;
37 }
38 
39 static int auxiliary_match(struct device *dev, struct device_driver *drv)
40 {
41 	struct auxiliary_device *auxdev = to_auxiliary_dev(dev);
42 	struct auxiliary_driver *auxdrv = to_auxiliary_drv(drv);
43 
44 	return !!auxiliary_match_id(auxdrv->id_table, auxdev);
45 }
46 
47 static int auxiliary_uevent(struct device *dev, struct kobj_uevent_env *env)
48 {
49 	const char *name, *p;
50 
51 	name = dev_name(dev);
52 	p = strrchr(name, '.');
53 
54 	return add_uevent_var(env, "MODALIAS=%s%.*s", AUXILIARY_MODULE_PREFIX,
55 			      (int)(p - name), name);
56 }
57 
58 static const struct dev_pm_ops auxiliary_dev_pm_ops = {
59 	SET_RUNTIME_PM_OPS(pm_generic_runtime_suspend, pm_generic_runtime_resume, NULL)
60 	SET_SYSTEM_SLEEP_PM_OPS(pm_generic_suspend, pm_generic_resume)
61 };
62 
63 static int auxiliary_bus_probe(struct device *dev)
64 {
65 	struct auxiliary_driver *auxdrv = to_auxiliary_drv(dev->driver);
66 	struct auxiliary_device *auxdev = to_auxiliary_dev(dev);
67 	int ret;
68 
69 	ret = dev_pm_domain_attach(dev, true);
70 	if (ret) {
71 		dev_warn(dev, "Failed to attach to PM Domain : %d\n", ret);
72 		return ret;
73 	}
74 
75 	ret = auxdrv->probe(auxdev, auxiliary_match_id(auxdrv->id_table, auxdev));
76 	if (ret)
77 		dev_pm_domain_detach(dev, true);
78 
79 	return ret;
80 }
81 
82 static int auxiliary_bus_remove(struct device *dev)
83 {
84 	struct auxiliary_driver *auxdrv = to_auxiliary_drv(dev->driver);
85 	struct auxiliary_device *auxdev = to_auxiliary_dev(dev);
86 
87 	if (auxdrv->remove)
88 		auxdrv->remove(auxdev);
89 	dev_pm_domain_detach(dev, true);
90 
91 	return 0;
92 }
93 
94 static void auxiliary_bus_shutdown(struct device *dev)
95 {
96 	struct auxiliary_driver *auxdrv = NULL;
97 	struct auxiliary_device *auxdev;
98 
99 	if (dev->driver) {
100 		auxdrv = to_auxiliary_drv(dev->driver);
101 		auxdev = to_auxiliary_dev(dev);
102 	}
103 
104 	if (auxdrv && auxdrv->shutdown)
105 		auxdrv->shutdown(auxdev);
106 }
107 
108 static struct bus_type auxiliary_bus_type = {
109 	.name = "auxiliary",
110 	.probe = auxiliary_bus_probe,
111 	.remove = auxiliary_bus_remove,
112 	.shutdown = auxiliary_bus_shutdown,
113 	.match = auxiliary_match,
114 	.uevent = auxiliary_uevent,
115 	.pm = &auxiliary_dev_pm_ops,
116 };
117 
118 /**
119  * auxiliary_device_init - check auxiliary_device and initialize
120  * @auxdev: auxiliary device struct
121  *
122  * This is the first step in the two-step process to register an
123  * auxiliary_device.
124  *
125  * When this function returns an error code, then the device_initialize will
126  * *not* have been performed, and the caller will be responsible to free any
127  * memory allocated for the auxiliary_device in the error path directly.
128  *
129  * It returns 0 on success.  On success, the device_initialize has been
130  * performed.  After this point any error unwinding will need to include a call
131  * to auxiliary_device_uninit().  In this post-initialize error scenario, a call
132  * to the device's .release callback will be triggered, and all memory clean-up
133  * is expected to be handled there.
134  */
135 int auxiliary_device_init(struct auxiliary_device *auxdev)
136 {
137 	struct device *dev = &auxdev->dev;
138 
139 	if (!dev->parent) {
140 		pr_err("auxiliary_device has a NULL dev->parent\n");
141 		return -EINVAL;
142 	}
143 
144 	if (!auxdev->name) {
145 		pr_err("auxiliary_device has a NULL name\n");
146 		return -EINVAL;
147 	}
148 
149 	dev->bus = &auxiliary_bus_type;
150 	device_initialize(&auxdev->dev);
151 	return 0;
152 }
153 EXPORT_SYMBOL_GPL(auxiliary_device_init);
154 
155 /**
156  * __auxiliary_device_add - add an auxiliary bus device
157  * @auxdev: auxiliary bus device to add to the bus
158  * @modname: name of the parent device's driver module
159  *
160  * This is the second step in the two-step process to register an
161  * auxiliary_device.
162  *
163  * This function must be called after a successful call to
164  * auxiliary_device_init(), which will perform the device_initialize.  This
165  * means that if this returns an error code, then a call to
166  * auxiliary_device_uninit() must be performed so that the .release callback
167  * will be triggered to free the memory associated with the auxiliary_device.
168  *
169  * The expectation is that users will call the "auxiliary_device_add" macro so
170  * that the caller's KBUILD_MODNAME is automatically inserted for the modname
171  * parameter.  Only if a user requires a custom name would this version be
172  * called directly.
173  */
174 int __auxiliary_device_add(struct auxiliary_device *auxdev, const char *modname)
175 {
176 	struct device *dev = &auxdev->dev;
177 	int ret;
178 
179 	if (!modname) {
180 		dev_err(dev, "auxiliary device modname is NULL\n");
181 		return -EINVAL;
182 	}
183 
184 	ret = dev_set_name(dev, "%s.%s.%d", modname, auxdev->name, auxdev->id);
185 	if (ret) {
186 		dev_err(dev, "auxiliary device dev_set_name failed: %d\n", ret);
187 		return ret;
188 	}
189 
190 	ret = device_add(dev);
191 	if (ret)
192 		dev_err(dev, "adding auxiliary device failed!: %d\n", ret);
193 
194 	return ret;
195 }
196 EXPORT_SYMBOL_GPL(__auxiliary_device_add);
197 
198 /**
199  * auxiliary_find_device - auxiliary device iterator for locating a particular device.
200  * @start: Device to begin with
201  * @data: Data to pass to match function
202  * @match: Callback function to check device
203  *
204  * This function returns a reference to a device that is 'found'
205  * for later use, as determined by the @match callback.
206  *
207  * The callback should return 0 if the device doesn't match and non-zero
208  * if it does.  If the callback returns non-zero, this function will
209  * return to the caller and not iterate over any more devices.
210  */
211 struct auxiliary_device *auxiliary_find_device(struct device *start,
212 					       const void *data,
213 					       int (*match)(struct device *dev, const void *data))
214 {
215 	struct device *dev;
216 
217 	dev = bus_find_device(&auxiliary_bus_type, start, data, match);
218 	if (!dev)
219 		return NULL;
220 
221 	return to_auxiliary_dev(dev);
222 }
223 EXPORT_SYMBOL_GPL(auxiliary_find_device);
224 
225 /**
226  * __auxiliary_driver_register - register a driver for auxiliary bus devices
227  * @auxdrv: auxiliary_driver structure
228  * @owner: owning module/driver
229  * @modname: KBUILD_MODNAME for parent driver
230  */
231 int __auxiliary_driver_register(struct auxiliary_driver *auxdrv,
232 				struct module *owner, const char *modname)
233 {
234 	int ret;
235 
236 	if (WARN_ON(!auxdrv->probe) || WARN_ON(!auxdrv->id_table))
237 		return -EINVAL;
238 
239 	if (auxdrv->name)
240 		auxdrv->driver.name = kasprintf(GFP_KERNEL, "%s.%s", modname,
241 						auxdrv->name);
242 	else
243 		auxdrv->driver.name = kasprintf(GFP_KERNEL, "%s", modname);
244 	if (!auxdrv->driver.name)
245 		return -ENOMEM;
246 
247 	auxdrv->driver.owner = owner;
248 	auxdrv->driver.bus = &auxiliary_bus_type;
249 	auxdrv->driver.mod_name = modname;
250 
251 	ret = driver_register(&auxdrv->driver);
252 	if (ret)
253 		kfree(auxdrv->driver.name);
254 
255 	return ret;
256 }
257 EXPORT_SYMBOL_GPL(__auxiliary_driver_register);
258 
259 /**
260  * auxiliary_driver_unregister - unregister a driver
261  * @auxdrv: auxiliary_driver structure
262  */
263 void auxiliary_driver_unregister(struct auxiliary_driver *auxdrv)
264 {
265 	driver_unregister(&auxdrv->driver);
266 	kfree(auxdrv->driver.name);
267 }
268 EXPORT_SYMBOL_GPL(auxiliary_driver_unregister);
269 
270 void __init auxiliary_bus_init(void)
271 {
272 	WARN_ON(bus_register(&auxiliary_bus_type));
273 }
274