linux/include/drm/drm_bridge.h

/*
 * Copyright (c) 2016 Intel Corporation
 *
 * Permission to use, copy, modify, distribute, and sell this software and its
 * documentation for any purpose is hereby granted without fee, provided that
 * the above copyright notice appear in all copies and that both that copyright
 * notice and this permission notice appear in supporting documentation, and
 * that the name of the copyright holders not be used in advertising or
 * publicity pertaining to distribution of the software without specific,
 * written prior permission.  The copyright holders make no representations
 * about the suitability of this software for any purpose.  It is provided "as
 * is" without express or implied warranty.
 *
 * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
 * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
 * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
 * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
 * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
 * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
 * OF THIS SOFTWARE.
 */

#ifndef __DRM_BRIDGE_H__
#define __DRM_BRIDGE_H__

#include <linux/list.h>
#include <linux/ctype.h>
#include <drm/drm_mode_object.h>
#include <drm/drm_modes.h>

struct drm_bridge;
struct drm_bridge_timings;
struct drm_panel;

/**
 * struct drm_bridge_funcs - drm_bridge control functions
 */
struct drm_bridge_funcs {
	/**
	 * @attach:
	 *
	 * This callback is invoked whenever our bridge is being attached to a
	 * &drm_encoder.
	 *
	 * The attach callback is optional.
	 *
	 * RETURNS:
	 *
	 * Zero on success, error code on failure.
	 */
	int (*attach)(struct drm_bridge *bridge);

	/**
	 * @detach:
	 *
	 * This callback is invoked whenever our bridge is being detached from a
	 * &drm_encoder.
	 *
	 * The detach callback is optional.
	 */
	void (*detach)(struct drm_bridge *bridge);

	/**
	 * @mode_valid:
	 *
	 * This callback is used to check if a specific mode is valid in this
	 * bridge. This should be implemented if the bridge has some sort of
	 * restriction in the modes it can display. For example, a given bridge
	 * may be responsible to set a clock value. If the clock can not
	 * produce all the values for the available modes then this callback
	 * can be used to restrict the number of modes to only the ones that
	 * can be displayed.
	 *
	 * This hook is used by the probe helpers to filter the mode list in
	 * drm_helper_probe_single_connector_modes(), and it is used by the
	 * atomic helpers to validate modes supplied by userspace in
	 * drm_atomic_helper_check_modeset().
	 *
	 * This function is optional.
	 *
	 * NOTE:
	 *
	 * Since this function is both called from the check phase of an atomic
	 * commit, and the mode validation in the probe paths it is not allowed
	 * to look at anything else but the passed-in mode, and validate it
	 * against configuration-invariant hardward constraints. Any further
	 * limits which depend upon the configuration can only be checked in
	 * @mode_fixup.
	 *
	 * RETURNS:
	 *
	 * drm_mode_status Enum
	 */
	enum drm_mode_status (*mode_valid)(struct drm_bridge *bridge,
					   const struct drm_display_mode *mode);

	/**
	 * @mode_fixup:
	 *
	 * This callback is used to validate and adjust a mode. The paramater
	 * mode is the display mode that should be fed to the next element in
	 * the display chain, either the final &drm_connector or the next
	 * &drm_bridge. The parameter adjusted_mode is the input mode the bridge
	 * requires. It can be modified by this callback and does not need to
	 * match mode. See also &drm_crtc_state.adjusted_mode for more details.
	 *
	 * This is the only hook that allows a bridge to reject a modeset. If
	 * this function passes all other callbacks must succeed for this
	 * configuration.
	 *
	 * The mode_fixup callback is optional.
	 *
	 * NOTE:
	 *
	 * This function is called in the check phase of atomic modesets, which
	 * can be aborted for any reason (including on userspace's request to
	 * just check whether a configuration would be possible). Drivers MUST
	 * NOT touch any persistent state (hardware or software) or data
	 * structures except the passed in @state parameter.
	 *
	 * Also beware that userspace can request its own custom modes, neither
	 * core nor helpers filter modes to the list of probe modes reported by
	 * the GETCONNECTOR IOCTL and stored in &drm_connector.modes. To ensure
	 * that modes are filtered consistently put any bridge constraints and
	 * limits checks into @mode_valid.
	 *
	 * RETURNS:
	 *
	 * True if an acceptable configuration is possible, false if the modeset
	 * operation should be rejected.
	 */
	bool (*mode_fixup)(struct drm_bridge *bridge,
			   const struct drm_display_mode *mode,
			   struct drm_display_mode *adjusted_mode);
	/**
	 * @disable:
	 *
	 * This callback should disable the bridge. It is called right before
	 * the preceding element in the display pipe is disabled. If the
	 * preceding element is a bridge this means it's called before that
	 * bridge's @disable vfunc. If the preceding element is a &drm_encoder
	 * it's called right before the &drm_encoder_helper_funcs.disable,
	 * &drm_encoder_helper_funcs.prepare or &drm_encoder_helper_funcs.dpms
	 * hook.
	 *
	 * The bridge can assume that the display pipe (i.e. clocks and timing
	 * signals) feeding it is still running when this callback is called.
	 *
	 * The disable callback is optional.
	 */
	void (*disable)(struct drm_bridge *bridge);

	/**
	 * @post_disable:
	 *
	 * This callback should disable the bridge. It is called right after the
	 * preceding element in the display pipe is disabled. If the preceding
	 * element is a bridge this means it's called after that bridge's
	 * @post_disable function. If the preceding element is a &drm_encoder
	 * it's called right after the encoder's
	 * &drm_encoder_helper_funcs.disable, &drm_encoder_helper_funcs.prepare
	 * or &drm_encoder_helper_funcs.dpms hook.
	 *
	 * The bridge must assume that the display pipe (i.e. clocks and timing
	 * singals) feeding it is no longer running when this callback is
	 * called.
	 *
	 * The post_disable callback is optional.
	 */
	void (*post_disable)(struct drm_bridge *bridge);

	/**
	 * @mode_set:
	 *
	 * This callback should set the given mode on the bridge. It is called
	 * after the @mode_set callback for the preceding element in the display
	 * pipeline has been called already. If the bridge is the first element
	 * then this would be &drm_encoder_helper_funcs.mode_set. The display
	 * pipe (i.e.  clocks and timing signals) is off when this function is
	 * called.
	 */
	void (*mode_set)(struct drm_bridge *bridge,
			 struct drm_display_mode *mode,
			 struct drm_display_mode *adjusted_mode);
	/**
	 * @pre_enable:
	 *
	 * This callback should enable the bridge. It is called right before
	 * the preceding element in the display pipe is enabled. If the
	 * preceding element is a bridge this means it's called before that
	 * bridge's @pre_enable function. If the preceding element is a
	 * &drm_encoder it's called right before the encoder's
	 * &drm_encoder_helper_funcs.enable, &drm_encoder_helper_funcs.commit or
	 * &drm_encoder_helper_funcs.dpms hook.
	 *
	 * The display pipe (i.e. clocks and timing signals) feeding this bridge
	 * will not yet be running when this callback is called. The bridge must
	 * not enable the display link feeding the next bridge in the chain (if
	 * there is one) when this callback is called.
	 *
	 * The pre_enable callback is optional.
	 */
	void (*pre_enable)(struct drm_bridge *bridge);

	/**
	 * @enable:
	 *
	 * This callback should enable the bridge. It is called right after
	 * the preceding element in the display pipe is enabled. If the
	 * preceding element is a bridge this means it's called after that
	 * bridge's @enable function. If the preceding element is a
	 * &drm_encoder it's called right after the encoder's
	 * &drm_encoder_helper_funcs.enable, &drm_encoder_helper_funcs.commit or
	 * &drm_encoder_helper_funcs.dpms hook.
	 *
	 * The bridge can assume that the display pipe (i.e. clocks and timing
	 * signals) feeding it is running when this callback is called. This
	 * callback must enable the display link feeding the next bridge in the
	 * chain if there is one.
	 *
	 * The enable callback is optional.
	 */
	void (*enable)(struct drm_bridge *bridge);
};

/**
 * struct drm_bridge_timings - timing information for the bridge
 */
struct drm_bridge_timings {
	/**
	 * @sampling_edge:
	 *
	 * Tells whether the bridge samples the digital input signal
	 * from the display engine on the positive or negative edge of the
	 * clock, this should reuse the DRM_BUS_FLAG_PIXDATA_[POS|NEG]EDGE
	 * bitwise flags from the DRM connector (bit 2 and 3 valid).
	 */
	u32 sampling_edge;
	/**
	 * @setup_time_ps:
	 *
	 * Defines the time in picoseconds the input data lines must be
	 * stable before the clock edge.
	 */
	u32 setup_time_ps;
	/**
	 * @hold_time_ps:
	 *
	 * Defines the time in picoseconds taken for the bridge to sample the
	 * input signal after the clock edge.
	 */
	u32 hold_time_ps;
};

/**
 * struct drm_bridge - central DRM bridge control structure
 * @dev: DRM device this bridge belongs to
 * @encoder: encoder to which this bridge is connected
 * @next: the next bridge in the encoder chain
 * @of_node: device node pointer to the bridge
 * @list: to keep track of all added bridges
 * @timings: the timing specification for the bridge, if any (may
 * be NULL)
 * @funcs: control functions
 * @driver_private: pointer to the bridge driver's internal context
 */
struct drm_bridge {
	struct drm_device *dev;
	struct drm_encoder *encoder;
	struct drm_bridge *next;
#ifdef CONFIG_OF
	struct device_node *of_node;
#endif
	struct list_head list;
	const struct drm_bridge_timings *timings;

	const struct drm_bridge_funcs *funcs;
	void *driver_private;
};

void drm_bridge_add(struct drm_bridge *bridge);
void drm_bridge_remove(struct drm_bridge *bridge);
struct drm_bridge *of_drm_find_bridge(struct device_node *np);
int drm_bridge_attach(struct drm_encoder *encoder, struct drm_bridge *bridge,
		      struct drm_bridge *previous);

bool drm_bridge_mode_fixup(struct drm_bridge *bridge,
			const struct drm_display_mode *mode,
			struct drm_display_mode *adjusted_mode);
enum drm_mode_status drm_bridge_mode_valid(struct drm_bridge *bridge,
					   const struct drm_display_mode *mode);
void drm_bridge_disable(struct drm_bridge *bridge);
void drm_bridge_post_disable(struct drm_bridge *bridge);
void drm_bridge_mode_set(struct drm_bridge *bridge,
			struct drm_display_mode *mode,
			struct drm_display_mode *adjusted_mode);
void drm_bridge_pre_enable(struct drm_bridge *bridge);
void drm_bridge_enable(struct drm_bridge *bridge);

#ifdef CONFIG_DRM_PANEL_BRIDGE
struct drm_bridge *drm_panel_bridge_add(struct drm_panel *panel,
					u32 connector_type);
void drm_panel_bridge_remove(struct drm_bridge *bridge);
struct drm_bridge *devm_drm_panel_bridge_add(struct device *dev,
					     struct drm_panel *panel,
					     u32 connector_type);
#endif

#endif