text: /* SPDX-License-Identifier: GPL-2.0 */
  /*
   * Copyright (c) 2016, NVIDIA CORPORATION.
   */
  
  #ifndef _RESET_H
  #define _RESET_H
  
  #include <dm/ofnode.h>
  #include <linux/err.h>
  
  /**
   * A reset is a hardware signal indicating that a HW module (or IP block, or
   * sometimes an entire off-CPU chip) reset all of its internal state to some
   * known-good initial state. Drivers will often reset HW modules when they
   * begin execution to ensure that hardware correctly responds to all requests,
   * or in response to some error condition. Reset signals are often controlled
   * externally to the HW module being reset, by an entity this API calls a reset
   * controller. This API provides a standard means for drivers to request that
   * reset controllers set or clear reset signals.
   *
   * A driver that implements UCLASS_RESET is a reset controller or provider. A
   * controller will often implement multiple separate reset signals, since the
   * hardware it manages often has this capability. reset-uclass.h describes the
   * interface which reset controllers must implement.
   *
   * Reset consumers/clients are the HW modules affected by reset signals. This
   * header file describes the API used by drivers for those HW modules.
   */
  
  struct udevice;
  
  /**
   * struct reset_ctl - A handle to (allowing control of) a single reset signal.
   *
   * Clients provide storage for reset control handles. The content of the
   * structure is managed solely by the reset API and reset drivers. A reset
   * control struct is initialized by "get"ing the reset control struct. The
   * reset control struct is passed to all other reset APIs to identify which
   * reset signal to operate upon.
   *
   * @dev: The device which implements the reset signal.
   * @id: The reset signal ID within the provider.
   * @data: An optional data field for scenarios where a single integer ID is not
   *	  sufficient. If used, it can be populated through an .of_xlate op and
   *	  processed during the various reset ops.
   * @polarity: An optional polarity field for drivers that support
   *	  different reset polarities.
   *
   * Should additional information to identify and configure any reset signal
   * for any provider be required in the future, the struct could be expanded to
   * either (a) add more fields to allow reset providers to store additional
   * information, or (b) replace the id field with an opaque pointer, which the
   * provider would dynamically allocated during its .of_xlate op, and process
   * during is .request op. This may require the addition of an extra op to clean
   * up the allocation.
   */
  struct reset_ctl {
  	struct udevice *dev;
  	/*
  	 * Written by of_xlate. In the future, we might add more fields here.
  	 */
  	unsigned long id;
  	unsigned long data;
  	unsigned long polarity;
  };
  
  /**
   * struct reset_ctl_bulk - A handle to (allowing control of) a bulk of reset
   * signals.
   *
   * Clients provide storage for the reset control bulk. The content of the
   * structure is managed solely by the reset API. A reset control bulk struct is
   * initialized by "get"ing the reset control bulk struct.
   * The reset control bulk struct is passed to all other bulk reset APIs to apply
   * the API to all the reset signals in the bulk struct.
   *
   * @resets: An array of reset signal handles handles.
   * @count: The number of reset signal handles in the reset array.
   */
  struct reset_ctl_bulk {
  	struct reset_ctl *resets;
  	unsigned int count;
  };
  
  #if CONFIG_IS_ENABLED(DM_RESET)
  
  /**
   * devm_reset_control_get - resource managed reset_get_by_name()
   * @dev: device to be reset by the controller
   * @id: reset line name
   *
   * Managed reset_get_by_name(). For reset controllers returned
   * from this function, reset_free() is called automatically on driver
   * detach.
   *
   * Returns a struct reset_ctl or IS_ERR() condition containing errno.
   */
  struct reset_ctl *devm_reset_control_get(struct udevice *dev, const char *id);
  
  /**
   * devm_reset_control_get_optional - resource managed reset_get_by_name() that
   *                                   can fail
   * @dev:	The client device.
   * @id:		reset line name
   *
   * Managed reset_get_by_name(). For reset controllers returned
   * from this function, reset_free() is called automatically on driver
   * detach.
   *
   * Returns a struct reset_ctl or a dummy reset controller if it failed.
   */
  struct reset_ctl *devm_reset_control_get_optional(struct udevice *dev,
  						  const char *id);
  
  /**
   * devm_reset_control_get - resource managed reset_get_by_index()
   * @dev:	The client device.
   * @index:	The index of the reset signal to request, within the client's
   *		list of reset signals.
   *
   * Managed reset_get_by_index(). For reset controllers returned
   * from this function, reset_free() is called automatically on driver
   * detach.
   *
   * Returns a struct reset_ctl or IS_ERR() condition containing errno.
   */
  struct reset_ctl *devm_reset_control_get_by_index(struct udevice *dev,
  						  int index);
  
  /**
   * devm_reset_bulk_get - resource managed reset_get_bulk()
   * @dev: device to be reset by the controller
   *
   * Managed reset_get_bulk(). For reset controllers returned
   * from this function, reset_free() is called automatically on driver
   * detach.
   *
   * Returns a struct reset_ctl or IS_ERR() condition containing errno.
   */
  struct reset_ctl_bulk *devm_reset_bulk_get(struct udevice *dev);
  
  /**
   * devm_reset_bulk_get_optional - resource managed reset_get_bulk() that
   *                                can fail
   * @dev:	The client device.
   *
   * Managed reset_get_bulk(). For reset controllers returned
   * from this function, reset_free() is called automatically on driver
   * detach.
   *
   * Returns a struct reset_ctl or NULL if it failed.
   */
  struct reset_ctl_bulk *devm_reset_bulk_get_optional(struct udevice *dev);
  
  /**
   * devm_reset_bulk_get_by_node - resource managed reset_get_bulk()
   * @dev: device to be reset by the controller
   * @node: ofnode where the "resets" property is. Usually a sub-node of
   *        the dev's node.
   *
   * see devm_reset_bulk_get()
   */
  struct reset_ctl_bulk *devm_reset_bulk_get_by_node(struct udevice *dev,
  						   ofnode node);
  
  /**
   * devm_reset_bulk_get_optional_by_node - resource managed reset_get_bulk()
   *                                        that can fail
   * @dev: device to be reset by the controller
   * @node: ofnode where the "resets" property is. Usually a sub-node of
   *        the dev's node.
   *
   * see devm_reset_bulk_get_optional()
   */
  struct reset_ctl_bulk *devm_reset_bulk_get_optional_by_node(struct udevice *dev,
  							    ofnode node);
  
  /**
   * reset_get_by_index - Get/request a reset signal by integer index.
   *
   * This looks up and requests a reset signal. The index is relative to the
   * client device; each device is assumed to have n reset signals associated
   * with it somehow, and this function finds and requests one of them. The
   * mapping of client device reset signal indices to provider reset signals may
   * be via device-tree properties, board-provided mapping tables, or some other
   * mechanism.
   *
   * @dev:	The client device.
   * @index:	The index of the reset signal to request, within the client's
   *		list of reset signals.
   * @reset_ctl	A pointer to a reset control struct to initialize.
   * @return 0 if OK, or a negative error code.
   */
  int reset_get_by_index(struct udevice *dev, int index,
  		       struct reset_ctl *reset_ctl);
  
  /**
   * reset_get_by_index_nodev - Get/request a reset signal by integer index
   * without a device.
   *
   * This is a version of reset_get_by_index() that does not use a device.
   *
   * @node:	The client ofnode.
   * @index:	The index of the reset signal to request, within the client's
   *		list of reset signals.
   * @reset_ctl	A pointer to a reset control struct to initialize.
   * @return 0 if OK, or a negative error code.
   */
  int reset_get_by_index_nodev(ofnode node, int index,
  			     struct reset_ctl *reset_ctl);
  
  /**
   * reset_get_bulk - Get/request all reset signals of a device.
   *
   * This looks up and requests all reset signals of the client device; each
   * device is assumed to have n reset signals associated with it somehow,
   * and this function finds and requests all of them in a separate structure.
   * The mapping of client device reset signals indices to provider reset signals
   * may be via device-tree properties, board-provided mapping tables, or some
   * other mechanism.
   *
   * @dev:	The client device.
   * @bulk	A pointer to a reset control bulk struct to initialize.
   * @return 0 if OK, or a negative error code.
   */
  int reset_get_bulk(struct udevice *dev, struct reset_ctl_bulk *bulk);
  
  /**
   * reset_get_by_name - Get/request a reset signal by name.
   *
   * This looks up and requests a reset signal. The name is relative to the
   * client device; each device is assumed to have n reset signals associated
   * with it somehow, and this function finds and requests one of them. The
   * mapping of client device reset signal names to provider reset signal may be
   * via device-tree properties, board-provided mapping tables, or some other
   * mechanism.
   *
   * @dev:	The client device.
   * @name:	The name of the reset signal to request, within the client's
   *		list of reset signals.
   * @reset_ctl:	A pointer to a reset control struct to initialize.
   * @return 0 if OK, or a negative error code.
   */
  int reset_get_by_name(struct udevice *dev, const char *name,
  		      struct reset_ctl *reset_ctl);
  
  /**
   * reset_request - Request a reset signal.
   *
   * @reset_ctl:	A reset control struct.
   *
   * @return 0 if OK, or a negative error code.
   */
  int reset_request(struct reset_ctl *reset_ctl);
  
  /**
   * reset_free - Free a previously requested reset signal.
   *
   * @reset_ctl:	A reset control struct that was previously successfully
   *		requested by reset_get_by_*().
   * @return 0 if OK, or a negative error code.
   */
  int reset_free(struct reset_ctl *reset_ctl);
  
  /**
   * reset_assert - Assert a reset signal.
   *
   * This function will assert the specified reset signal, thus resetting the
   * affected HW module(s). Depending on the reset controller hardware, the reset
   * signal will either stay asserted until reset_deassert() is called, or the
   * hardware may autonomously clear the reset signal itself.
   *
   * @reset_ctl:	A reset control struct that was previously successfully
   *		requested by reset_get_by_*().
   * @return 0 if OK, or a negative error code.
   */
  int reset_assert(struct reset_ctl *reset_ctl);
  
  /**
   * reset_assert_bulk - Assert all reset signals in a reset control bulk struct.
   *
   * This function will assert the specified reset signals in a reset control
   * bulk struct, thus resetting the affected HW module(s). Depending on the
   * reset controller hardware, the reset signals will either stay asserted
   * until reset_deassert_bulk() is called, or the hardware may autonomously
   * clear the reset signals itself.
   *
   * @bulk:	A reset control bulk struct that was previously successfully
   *		requested by reset_get_bulk().
   * @return 0 if OK, or a negative error code.
   */
  int reset_assert_bulk(struct reset_ctl_bulk *bulk);
  
  /**
   * reset_deassert - Deassert a reset signal.
   *
   * This function will deassert the specified reset signal, thus releasing the
   * affected HW modules() from reset, and allowing them to continue normal
   * operation.
   *
   * @reset_ctl:	A reset control struct that was previously successfully
   *		requested by reset_get_by_*().
   * @return 0 if OK, or a negative error code.
   */
  int reset_deassert(struct reset_ctl *reset_ctl);
  
  /**
   * reset_deassert_bulk - Deassert all reset signals in a reset control bulk
   * struct.
   *
   * This function will deassert the specified reset signals in a reset control
   * bulk struct, thus releasing the affected HW modules() from reset, and
   * allowing them to continue normal operation.
   *
   * @bulk:	A reset control bulk struct that was previously successfully
   *		requested by reset_get_bulk().
   * @return 0 if OK, or a negative error code.
   */
  int reset_deassert_bulk(struct reset_ctl_bulk *bulk);
  
  /**
   * rst_status - Check reset signal status.
   *
   * @reset_ctl:	The reset signal to check.
   * @return 0 if deasserted, positive if asserted, or a negative
   *           error code.
   */
  int reset_status(struct reset_ctl *reset_ctl);
  
  /**
   * reset_release_all - Assert/Free an array of previously requested resets.
   *
   * For each reset contained in the reset array, this function will check if
   * reset has been previously requested and then will assert and free it.
   *
   * @reset_ctl:	A reset struct array that was previously successfully
   *		requested by reset_get_by_*().
   * @count	Number of reset contained in the array
   * @return 0 if OK, or a negative error code.
   */
  int reset_release_all(struct reset_ctl *reset_ctl, int count);
  
  /**
   * reset_release_bulk - Assert/Free an array of previously requested reset
   * signals in a reset control bulk struct.
   *
   * For each reset contained in the reset control bulk struct, this function
   * will check if reset has been previously requested and then will assert
   * and free it.
   *
   * @bulk:	A reset control bulk struct that was previously successfully
   *		requested by reset_get_bulk().
   * @return 0 if OK, or a negative error code.
   */
  static inline int reset_release_bulk(struct reset_ctl_bulk *bulk)
  {
  	return reset_release_all(bulk->resets, bulk->count);
  }
  
  #else
  static inline struct reset_ctl *devm_reset_control_get(struct udevice *dev,
  						       const char *id)
  {
  	return ERR_PTR(-ENOTSUPP);
  }
  
  static inline struct reset_ctl *devm_reset_control_get_optional(struct udevice *dev,
  								const char *id)
  {
  	return NULL;
  }
  
  static inline struct reset_ctl *devm_reset_control_get_by_index(struct udevice *dev,
  								int index)
  {
  	return ERR_PTR(-ENOTSUPP);
  }
  
  static inline struct reset_ctl_bulk *devm_reset_bulk_get(struct udevice *dev)
  {
  	return ERR_PTR(-ENOTSUPP);
  }
  
  static inline struct reset_ctl_bulk *devm_reset_bulk_get_optional(struct udevice *dev)
  {
  	return NULL;
  }
  
  static inline struct reset_ctl_bulk *devm_reset_bulk_get_by_node(struct udevice *dev,
  								 ofnode node)
  {
  	return ERR_PTR(-ENOTSUPP);
  }
  
  static inline struct reset_ctl_bulk *devm_reset_bulk_get_optional_by_node(struct udevice *dev,
  									  ofnode node)
  {
  	return NULL;
  }
  
  static inline int reset_get_by_index(struct udevice *dev, int index,
  				     struct reset_ctl *reset_ctl)
  {
  	return -ENOTSUPP;
  }
  
  static inline int reset_get_bulk(struct udevice *dev,
  				 struct reset_ctl_bulk *bulk)
  {
  	return -ENOTSUPP;
  }
  
  static inline int reset_get_by_name(struct udevice *dev, const char *name,
  				    struct reset_ctl *reset_ctl)
  {
  	return -ENOTSUPP;
  }
  
  static inline int reset_free(struct reset_ctl *reset_ctl)
  {
  	return 0;
  }
  
  static inline int reset_assert(struct reset_ctl *reset_ctl)
  {
  	return 0;
  }
  
  static inline int reset_assert_bulk(struct reset_ctl_bulk *bulk)
  {
  	return 0;
  }
  
  static inline int reset_deassert(struct reset_ctl *reset_ctl)
  {
  	return 0;
  }
  
  static inline int reset_deassert_bulk(struct reset_ctl_bulk *bulk)
  {
  	return 0;
  }
  
  static inline int reset_status(struct reset_ctl *reset_ctl)
  {
  	return -ENOTSUPP;
  }
  
  static inline int reset_release_all(struct reset_ctl *reset_ctl, int count)
  {
  	return 0;
  }
  
  static inline int reset_release_bulk(struct reset_ctl_bulk *bulk)
  {
  	return 0;
  }
  #endif
  
  /**
   * reset_valid() - check if reset is valid
   *
   * @reset_ctl:		the reset to check
   * @return TRUE if valid, or FALSE
   */
  static inline bool reset_valid(struct reset_ctl *reset_ctl)
  {
  	return !!reset_ctl->dev;
  }
  
  #endif
  