text: /*
   * Copyright (C) 2009 Francisco Jerez.
   * All Rights Reserved.
   *
   * Permission is hereby granted, free of charge, to any person obtaining
   * a copy of this software and associated documentation files (the
   * "Software"), to deal in the Software without restriction, including
   * without limitation the rights to use, copy, modify, merge, publish,
   * distribute, sublicense, and/or sell copies of the Software, and to
   * permit persons to whom the Software is furnished to do so, subject to
   * the following conditions:
   *
   * The above copyright notice and this permission notice (including the
   * next paragraph) shall be included in all copies or substantial
   * portions of the Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
   * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
   * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
   * IN NO EVENT SHALL THE COPYRIGHT OWNER(S) AND/OR ITS SUPPLIERS BE
   * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
   * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
   * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
   *
   */
  
  #include <linux/module.h>
  
  #include <drm/drm_encoder_slave.h>
  
  /**
   * drm_i2c_encoder_init - Initialize an I2C slave encoder
   * @dev:	DRM device.
   * @encoder:    Encoder to be attached to the I2C device. You aren't
   *		required to have called drm_encoder_init() before.
   * @adap:	I2C adapter that will be used to communicate with
   *		the device.
   * @info:	Information that will be used to create the I2C device.
   *		Required fields are @addr and @type.
   *
   * Create an I2C device on the specified bus (the module containing its
   * driver is transparently loaded) and attach it to the specified
   * &drm_encoder_slave. The @slave_funcs field will be initialized with
   * the hooks provided by the slave driver.
   *
   * If @info->platform_data is non-NULL it will be used as the initial
   * slave config.
   *
   * Returns 0 on success or a negative errno on failure, in particular,
   * -ENODEV is returned when no matching driver is found.
   */
  int drm_i2c_encoder_init(struct drm_device *dev,
  			 struct drm_encoder_slave *encoder,
  			 struct i2c_adapter *adap,
  			 const struct i2c_board_info *info)
  {
  	struct module *module = NULL;
  	struct i2c_client *client;
  	struct drm_i2c_encoder_driver *encoder_drv;
  	int err = 0;
  
  	request_module("%s%s", I2C_MODULE_PREFIX, info->type);
  
  	client = i2c_new_device(adap, info);
  	if (!client) {
  		err = -ENOMEM;
  		goto fail;
  	}
  
  	if (!client->dev.driver) {
  		err = -ENODEV;
  		goto fail_unregister;
  	}
  
  	module = client->dev.driver->owner;
  	if (!try_module_get(module)) {
  		err = -ENODEV;
  		goto fail_unregister;
  	}
  
  	encoder->bus_priv = client;
  
  	encoder_drv = to_drm_i2c_encoder_driver(to_i2c_driver(client->dev.driver));
  
  	err = encoder_drv->encoder_init(client, dev, encoder);
  	if (err)
  		goto fail_unregister;
  
  	if (info->platform_data)
  		encoder->slave_funcs->set_config(&encoder->base,
  						 info->platform_data);
  
  	return 0;
  
  fail_unregister:
  	i2c_unregister_device(client);
  	module_put(module);
  fail:
  	return err;
  }
  EXPORT_SYMBOL(drm_i2c_encoder_init);
  
  /**
   * drm_i2c_encoder_destroy - Unregister the I2C device backing an encoder
   * @drm_encoder:	Encoder to be unregistered.
   *
   * This should be called from the @destroy method of an I2C slave
   * encoder driver once I2C access is no longer needed.
   */
  void drm_i2c_encoder_destroy(struct drm_encoder *drm_encoder)
  {
  	struct drm_encoder_slave *encoder = to_encoder_slave(drm_encoder);
  	struct i2c_client *client = drm_i2c_encoder_get_client(drm_encoder);
  	struct module *module = client->dev.driver->owner;
  
  	i2c_unregister_device(client);
  	encoder->bus_priv = NULL;
  
  	module_put(module);
  }
  EXPORT_SYMBOL(drm_i2c_encoder_destroy);
  
  /*
   * Wrapper fxns which can be plugged in to drm_encoder_helper_funcs:
   */
  
  static inline struct drm_encoder_slave_funcs *
  get_slave_funcs(struct drm_encoder *enc)
  {
  	return to_encoder_slave(enc)->slave_funcs;
  }
  
  void drm_i2c_encoder_dpms(struct drm_encoder *encoder, int mode)
  {
  	get_slave_funcs(encoder)->dpms(encoder, mode);
  }
  EXPORT_SYMBOL(drm_i2c_encoder_dpms);
  
  bool drm_i2c_encoder_mode_fixup(struct drm_encoder *encoder,
  		const struct drm_display_mode *mode,
  		struct drm_display_mode *adjusted_mode)
  {
  	return get_slave_funcs(encoder)->mode_fixup(encoder, mode, adjusted_mode);
  }
  EXPORT_SYMBOL(drm_i2c_encoder_mode_fixup);
  
  void drm_i2c_encoder_prepare(struct drm_encoder *encoder)
  {
  	drm_i2c_encoder_dpms(encoder, DRM_MODE_DPMS_OFF);
  }
  EXPORT_SYMBOL(drm_i2c_encoder_prepare);
  
  void drm_i2c_encoder_commit(struct drm_encoder *encoder)
  {
  	drm_i2c_encoder_dpms(encoder, DRM_MODE_DPMS_ON);
  }
  EXPORT_SYMBOL(drm_i2c_encoder_commit);
  
  void drm_i2c_encoder_mode_set(struct drm_encoder *encoder,
  		struct drm_display_mode *mode,
  		struct drm_display_mode *adjusted_mode)
  {
  	get_slave_funcs(encoder)->mode_set(encoder, mode, adjusted_mode);
  }
  EXPORT_SYMBOL(drm_i2c_encoder_mode_set);
  
  enum drm_connector_status drm_i2c_encoder_detect(struct drm_encoder *encoder,
  	    struct drm_connector *connector)
  {
  	return get_slave_funcs(encoder)->detect(encoder, connector);
  }
  EXPORT_SYMBOL(drm_i2c_encoder_detect);
  
  void drm_i2c_encoder_save(struct drm_encoder *encoder)
  {
  	get_slave_funcs(encoder)->save(encoder);
  }
  EXPORT_SYMBOL(drm_i2c_encoder_save);
  
  void drm_i2c_encoder_restore(struct drm_encoder *encoder)
  {
  	get_slave_funcs(encoder)->restore(encoder);
  }
  EXPORT_SYMBOL(drm_i2c_encoder_restore);
  