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drm_encoder_slave.c revision 1.1 
      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