1 /*
2  * Copyright (C) 2009 Francisco Jerez.
3  * All Rights Reserved.
4  *
5  * Permission is hereby granted, free of charge, to any person obtaining
6  * a copy of this software and associated documentation files (the
7  * "Software"), to deal in the Software without restriction, including
8  * without limitation the rights to use, copy, modify, merge, publish,
9  * distribute, sublicense, and/or sell copies of the Software, and to
10  * permit persons to whom the Software is furnished to do so, subject to
11  * the following conditions:
12  *
13  * The above copyright notice and this permission notice (including the
14  * next paragraph) shall be included in all copies or substantial
15  * portions of the Software.
16  *
17  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
18  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
19  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
20  * IN NO EVENT SHALL THE COPYRIGHT OWNER(S) AND/OR ITS SUPPLIERS BE
21  * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
22  * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
23  * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
24  *
25  */
26 
27 #include "drm_encoder_slave.h"
28 
29 /**
30  * drm_i2c_encoder_init - Initialize an I2C slave encoder
31  * @dev:	DRM device.
32  * @encoder:    Encoder to be attached to the I2C device. You aren't
33  *		required to have called drm_encoder_init() before.
34  * @adap:	I2C adapter that will be used to communicate with
35  *		the device.
36  * @info:	Information that will be used to create the I2C device.
37  *		Required fields are @addr and @type.
38  *
39  * Create an I2C device on the specified bus (the module containing its
40  * driver is transparently loaded) and attach it to the specified
41  * &drm_encoder_slave. The @slave_funcs field will be initialized with
42  * the hooks provided by the slave driver.
43  *
44  * Returns 0 on success or a negative errno on failure, in particular,
45  * -ENODEV is returned when no matching driver is found.
46  */
47 int drm_i2c_encoder_init(struct drm_device *dev,
48 			 struct drm_encoder_slave *encoder,
49 			 struct i2c_adapter *adap,
50 			 const struct i2c_board_info *info)
51 {
52 	char modalias[sizeof(I2C_MODULE_PREFIX)
53 		      + I2C_NAME_SIZE];
54 	struct module *module = NULL;
55 	struct i2c_client *client;
56 	struct drm_i2c_encoder_driver *encoder_drv;
57 	int err = 0;
58 
59 	snprintf(modalias, sizeof(modalias),
60 		 "%s%s", I2C_MODULE_PREFIX, info->type);
61 	request_module(modalias);
62 
63 	client = i2c_new_device(adap, info);
64 	if (!client) {
65 		err = -ENOMEM;
66 		goto fail;
67 	}
68 
69 	if (!client->driver) {
70 		err = -ENODEV;
71 		goto fail_unregister;
72 	}
73 
74 	module = client->driver->driver.owner;
75 	if (!try_module_get(module)) {
76 		err = -ENODEV;
77 		goto fail_unregister;
78 	}
79 
80 	encoder->bus_priv = client;
81 
82 	encoder_drv = to_drm_i2c_encoder_driver(client->driver);
83 
84 	err = encoder_drv->encoder_init(client, dev, encoder);
85 	if (err)
86 		goto fail_unregister;
87 
88 	return 0;
89 
90 fail_unregister:
91 	i2c_unregister_device(client);
92 	module_put(module);
93 fail:
94 	return err;
95 }
96 EXPORT_SYMBOL(drm_i2c_encoder_init);
97 
98 /**
99  * drm_i2c_encoder_destroy - Unregister the I2C device backing an encoder
100  * @drm_encoder:	Encoder to be unregistered.
101  *
102  * This should be called from the @destroy method of an I2C slave
103  * encoder driver once I2C access is no longer needed.
104  */
105 void drm_i2c_encoder_destroy(struct drm_encoder *drm_encoder)
106 {
107 	struct drm_encoder_slave *encoder = to_encoder_slave(drm_encoder);
108 	struct i2c_client *client = drm_i2c_encoder_get_client(drm_encoder);
109 	struct module *module = client->driver->driver.owner;
110 
111 	i2c_unregister_device(client);
112 	encoder->bus_priv = NULL;
113 
114 	module_put(module);
115 }
116 EXPORT_SYMBOL(drm_i2c_encoder_destroy);
117