root/include/drm/drm_vblank.h
/*
 * Copyright 2016 Intel Corp.
 *
 * 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
 * VA LINUX SYSTEMS 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.
 */

#ifndef _DRM_VBLANK_H_
#define _DRM_VBLANK_H_

#include <linux/seqlock.h>
#include <linux/hrtimer.h>
#include <linux/idr.h>
#include <linux/poll.h>
#include <linux/kthread.h>

#include <drm/drm_file.h>
#include <drm/drm_modes.h>

struct drm_device;
struct drm_crtc;
struct drm_vblank_work;

/**
 * struct drm_pending_vblank_event - pending vblank event tracking
 */
struct drm_pending_vblank_event {
        /**
         * @base: Base structure for tracking pending DRM events.
         */
        struct drm_pending_event base;
        /**
         * @pipe: drm_crtc_index() of the &drm_crtc this event is for.
         */
        unsigned int pipe;
        /**
         * @sequence: frame event should be triggered at
         */
        u64 sequence;
        /**
         * @event: Actual event which will be sent to userspace.
         */
        union {
                /**
                 * @event.base: DRM event base class.
                 */
                struct drm_event base;

                /**
                 * @event.vbl:
                 *
                 * Event payload for vblank events, requested through
                 * either the MODE_PAGE_FLIP or MODE_ATOMIC IOCTL. Also
                 * generated by the legacy WAIT_VBLANK IOCTL, but new userspace
                 * should use MODE_QUEUE_SEQUENCE and &event.seq instead.
                 */
                struct drm_event_vblank vbl;

                /**
                 * @event.seq: Event payload for the MODE_QUEUEU_SEQUENCE IOCTL.
                 */
                struct drm_event_crtc_sequence seq;
        } event;
};

/**
 * struct drm_vblank_crtc_config - vblank configuration for a CRTC
 */
struct drm_vblank_crtc_config {
        /**
         * @offdelay_ms: Vblank off delay in ms, used to determine how long
         * &drm_vblank_crtc.disable_timer waits before disabling.
         *
         * Defaults to the value of drm_vblank_offdelay in drm_crtc_vblank_on().
         */
        int offdelay_ms;

        /**
         * @disable_immediate: See &drm_device.vblank_disable_immediate
         * for the exact semantics of immediate vblank disabling.
         *
         * Additionally, this tracks the disable immediate value per crtc, just
         * in case it needs to differ from the default value for a given device.
         *
         * Defaults to the value of &drm_device.vblank_disable_immediate in
         * drm_crtc_vblank_on().
         */
        bool disable_immediate;
};

/**
 * struct drm_vblank_crtc_timer - vblank timer for a CRTC
 */
struct drm_vblank_crtc_timer {
        /**
         * @timer: The vblank's high-resolution timer
         */
        struct hrtimer timer;
        /**
         * @interval_lock: Protects @interval
         */
        spinlock_t interval_lock;
        /**
         * @interval: Duration between two vblanks
         */
        ktime_t interval;
        /**
         * @crtc: The timer's CRTC
         */
        struct drm_crtc *crtc;
};

/**
 * struct drm_vblank_crtc - vblank tracking for a CRTC
 *
 * This structure tracks the vblank state for one CRTC.
 *
 * Note that for historical reasons - the vblank handling code is still shared
 * with legacy/non-kms drivers - this is a free-standing structure not directly
 * connected to &struct drm_crtc. But all public interface functions are taking
 * a &struct drm_crtc to hide this implementation detail.
 */
struct drm_vblank_crtc {
        /**
         * @dev: Pointer to the &drm_device.
         */
        struct drm_device *dev;
        /**
         * @queue: Wait queue for vblank waiters.
         */
        wait_queue_head_t queue;
        /**
         * @disable_timer: Disable timer for the delayed vblank disabling
         * hysteresis logic. Vblank disabling is controlled through
         * &drm_vblank_crtc_config.offdelay_ms and the setting of the
         * &drm_device.max_vblank_count value.
         */
        struct timer_list disable_timer;

        /**
         * @seqlock: Protect vblank count and time.
         */
        seqlock_t seqlock;

        /**
         * @count:
         *
         * Current software vblank counter.
         *
         * Note that for a given vblank counter value drm_crtc_handle_vblank()
         * and drm_crtc_vblank_count() or drm_crtc_vblank_count_and_time()
         * provide a barrier: Any writes done before calling
         * drm_crtc_handle_vblank() will be visible to callers of the later
         * functions, iff the vblank count is the same or a later one.
         *
         * IMPORTANT: This guarantee requires barriers, therefor never access
         * this field directly. Use drm_crtc_vblank_count() instead.
         */
        atomic64_t count;
        /**
         * @time: Vblank timestamp corresponding to @count.
         */
        ktime_t time;

        /**
         * @refcount: Number of users/waiters of the vblank interrupt. Only when
         * this refcount reaches 0 can the hardware interrupt be disabled using
         * @disable_timer.
         */
        atomic_t refcount;
        /**
         * @last: Protected by &drm_device.vbl_lock, used for wraparound handling.
         */
        u32 last;
        /**
         * @max_vblank_count:
         *
         * Maximum value of the vblank registers for this crtc. This value +1
         * will result in a wrap-around of the vblank register. It is used
         * by the vblank core to handle wrap-arounds.
         *
         * If set to zero the vblank core will try to guess the elapsed vblanks
         * between times when the vblank interrupt is disabled through
         * high-precision timestamps. That approach is suffering from small
         * races and imprecision over longer time periods, hence exposing a
         * hardware vblank counter is always recommended.
         *
         * This is the runtime configurable per-crtc maximum set through
         * drm_crtc_set_max_vblank_count(). If this is used the driver
         * must leave the device wide &drm_device.max_vblank_count at zero.
         *
         * If non-zero, &drm_crtc_funcs.get_vblank_counter must be set.
         */
        u32 max_vblank_count;
        /**
         * @inmodeset: Tracks whether the vblank is disabled due to a modeset.
         * For legacy driver bit 2 additionally tracks whether an additional
         * temporary vblank reference has been acquired to paper over the
         * hardware counter resetting/jumping. KMS drivers should instead just
         * call drm_crtc_vblank_off() and drm_crtc_vblank_on(), which explicitly
         * save and restore the vblank count.
         */
        unsigned int inmodeset;
        /**
         * @pipe: drm_crtc_index() of the &drm_crtc corresponding to this
         * structure.
         */
        unsigned int pipe;
        /**
         * @framedur_ns: Frame/Field duration in ns, used by
         * drm_crtc_vblank_helper_get_vblank_timestamp() and computed by
         * drm_calc_timestamping_constants().
         */
        int framedur_ns;
        /**
         * @linedur_ns: Line duration in ns, used by
         * drm_crtc_vblank_helper_get_vblank_timestamp() and computed by
         * drm_calc_timestamping_constants().
         */
        int linedur_ns;

        /**
         * @hwmode:
         *
         * Cache of the current hardware display mode. Only valid when @enabled
         * is set. This is used by helpers like
         * drm_crtc_vblank_helper_get_vblank_timestamp(). We can't just access
         * the hardware mode by e.g. looking at &drm_crtc_state.adjusted_mode,
         * because that one is really hard to get from interrupt context.
         */
        struct drm_display_mode hwmode;

        /**
         * @config: Stores vblank configuration values for a given CRTC.
         * Also, see drm_crtc_vblank_on_config().
         */
        struct drm_vblank_crtc_config config;

        /**
         * @enabled: Tracks the enabling state of the corresponding &drm_crtc to
         * avoid double-disabling and hence corrupting saved state. Needed by
         * drivers not using atomic KMS, since those might go through their CRTC
         * disabling functions multiple times.
         */
        bool enabled;

        /**
         * @worker: The &kthread_worker used for executing vblank works.
         */
        struct kthread_worker *worker;

        /**
         * @pending_work: A list of scheduled &drm_vblank_work items that are
         * waiting for a future vblank.
         */
        struct list_head pending_work;

        /**
         * @work_wait_queue: The wait queue used for signaling that a
         * &drm_vblank_work item has either finished executing, or was
         * cancelled.
         */
        wait_queue_head_t work_wait_queue;

        /**
         * @vblank_timer: Holds the state of the vblank timer
         */
        struct drm_vblank_crtc_timer vblank_timer;
};

struct drm_vblank_crtc *drm_crtc_vblank_crtc(struct drm_crtc *crtc);
int drm_vblank_init(struct drm_device *dev, unsigned int num_crtcs);
bool drm_dev_has_vblank(const struct drm_device *dev);
u64 drm_crtc_vblank_count(struct drm_crtc *crtc);
u64 drm_crtc_vblank_count_and_time(struct drm_crtc *crtc,
                                   ktime_t *vblanktime);
int drm_crtc_next_vblank_start(struct drm_crtc *crtc, ktime_t *vblanktime);
void drm_crtc_send_vblank_event(struct drm_crtc *crtc,
                               struct drm_pending_vblank_event *e);
void drm_crtc_arm_vblank_event(struct drm_crtc *crtc,
                              struct drm_pending_vblank_event *e);
void drm_vblank_set_event(struct drm_pending_vblank_event *e,
                          u64 *seq,
                          ktime_t *now);
bool drm_handle_vblank(struct drm_device *dev, unsigned int pipe);
bool drm_crtc_handle_vblank(struct drm_crtc *crtc);
int drm_crtc_vblank_get(struct drm_crtc *crtc);
void drm_crtc_vblank_put(struct drm_crtc *crtc);
int drm_crtc_wait_one_vblank(struct drm_crtc *crtc);
void drm_crtc_vblank_off(struct drm_crtc *crtc);
void drm_crtc_vblank_reset(struct drm_crtc *crtc);
void drm_crtc_vblank_on_config(struct drm_crtc *crtc,
                               const struct drm_vblank_crtc_config *config);
void drm_crtc_vblank_on(struct drm_crtc *crtc);
u64 drm_crtc_accurate_vblank_count(struct drm_crtc *crtc);
void drm_crtc_vblank_restore(struct drm_crtc *crtc);

void drm_calc_timestamping_constants(struct drm_crtc *crtc,
                                     const struct drm_display_mode *mode);
wait_queue_head_t *drm_crtc_vblank_waitqueue(struct drm_crtc *crtc);
void drm_crtc_set_max_vblank_count(struct drm_crtc *crtc,
                                   u32 max_vblank_count);

int drm_crtc_vblank_start_timer(struct drm_crtc *crtc);
void drm_crtc_vblank_cancel_timer(struct drm_crtc *crtc);
void drm_crtc_vblank_get_vblank_timeout(struct drm_crtc *crtc, ktime_t *vblank_time);

/*
 * Helpers for struct drm_crtc_funcs
 */

typedef bool (*drm_vblank_get_scanout_position_func)(struct drm_crtc *crtc,
                                                     bool in_vblank_irq,
                                                     int *vpos, int *hpos,
                                                     ktime_t *stime,
                                                     ktime_t *etime,
                                                     const struct drm_display_mode *mode);

bool
drm_crtc_vblank_helper_get_vblank_timestamp_internal(struct drm_crtc *crtc,
                                                     int *max_error,
                                                     ktime_t *vblank_time,
                                                     bool in_vblank_irq,
                                                     drm_vblank_get_scanout_position_func get_scanout_position);
bool drm_crtc_vblank_helper_get_vblank_timestamp(struct drm_crtc *crtc,
                                                 int *max_error,
                                                 ktime_t *vblank_time,
                                                 bool in_vblank_irq);

#endif