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 <linux/module.h>
28 
29 #include <drm/drm_encoder_slave.h>
30 
31 /**
32  * drm_i2c_encoder_init - Initialize an I2C slave encoder
33  * @dev:	DRM device.
34  * @encoder:    Encoder to be attached to the I2C device. You aren't
35  *		required to have called drm_encoder_init() before.
36  * @adap:	I2C adapter that will be used to communicate with
37  *		the device.
38  * @info:	Information that will be used to create the I2C device.
39  *		Required fields are @addr and @type.
40  *
41  * Create an I2C device on the specified bus (the module containing its
42  * driver is transparently loaded) and attach it to the specified
43  * &drm_encoder_slave. The @slave_funcs field will be initialized with
44  * the hooks provided by the slave driver.
45  *
46  * If @info->platform_data is non-NULL it will be used as the initial
47  * slave config.
48  *
49  * Returns 0 on success or a negative errno on failure, in particular,
50  * -ENODEV is returned when no matching driver is found.
51  */
52 int drm_i2c_encoder_init(struct drm_device *dev,
53 			 struct drm_encoder_slave *encoder,
54 			 struct i2c_adapter *adap,
55 			 const struct i2c_board_info *info)
56 {
57 	char modalias[sizeof(I2C_MODULE_PREFIX)
58 		      + I2C_NAME_SIZE];
59 	struct module *module = NULL;
60 	struct i2c_client *client;
61 	struct drm_i2c_encoder_driver *encoder_drv;
62 	int err = 0;
63 
64 	snprintf(modalias, sizeof(modalias),
65 		 "%s%s", I2C_MODULE_PREFIX, info->type);
66 	request_module(modalias);
67 
68 	client = i2c_new_device(adap, info);
69 	if (!client) {
70 		err = -ENOMEM;
71 		goto fail;
72 	}
73 
74 	if (!client->driver) {
75 		err = -ENODEV;
76 		goto fail_unregister;
77 	}
78 
79 	module = client->driver->driver.owner;
80 	if (!try_module_get(module)) {
81 		err = -ENODEV;
82 		goto fail_unregister;
83 	}
84 
85 	encoder->bus_priv = client;
86 
87 	encoder_drv = to_drm_i2c_encoder_driver(client->driver);
88 
89 	err = encoder_drv->encoder_init(client, dev, encoder);
90 	if (err)
91 		goto fail_unregister;
92 
93 	if (info->platform_data)
94 		encoder->slave_funcs->set_config(&encoder->base,
95 						 info->platform_data);
96 
97 	return 0;
98 
99 fail_unregister:
100 	i2c_unregister_device(client);
101 	module_put(module);
102 fail:
103 	return err;
104 }
105 EXPORT_SYMBOL(drm_i2c_encoder_init);
106 
107 /**
108  * drm_i2c_encoder_destroy - Unregister the I2C device backing an encoder
109  * @drm_encoder:	Encoder to be unregistered.
110  *
111  * This should be called from the @destroy method of an I2C slave
112  * encoder driver once I2C access is no longer needed.
113  */
114 void drm_i2c_encoder_destroy(struct drm_encoder *drm_encoder)
115 {
116 	struct drm_encoder_slave *encoder = to_encoder_slave(drm_encoder);
117 	struct i2c_client *client = drm_i2c_encoder_get_client(drm_encoder);
118 	struct module *module = client->driver->driver.owner;
119 
120 	i2c_unregister_device(client);
121 	encoder->bus_priv = NULL;
122 
123 	module_put(module);
124 }
125 EXPORT_SYMBOL(drm_i2c_encoder_destroy);
126