/* SPDX-License-Identifier: MIT */
/*
 * Copyright © 2019 Intel Corporation
 */

#ifndef __INTEL_RESET_TYPES_H_
#define __INTEL_RESET_TYPES_H_

#include <linux/mutex.h>
#include <linux/wait.h>
#include <linux/srcu.h>

struct intel_reset {
        /**
         * flags: Control various stages of the GPU reset
         *
         * #I915_RESET_BACKOFF - When we start a global reset, we need to
         * serialise with any other users attempting to do the same, and
         * any global resources that may be clobber by the reset (such as
         * FENCE registers).
         *
         * #I915_RESET_ENGINE[num_engines] - Since the driver doesn't need to
         * acquire a global lock to reset an engine, we need an explicit
         * flag to prevent two concurrent reset attempts in the same engine.
         * As the number of engines continues to grow, allocate the flags from
         * the most significant bits.
         *
         * #I915_WEDGED - If reset fails and we can no longer use the GPU,
         * we set the #I915_WEDGED bit. Prior to command submission, e.g.
         * i915_request_alloc(), this bit is checked and the sequence
         * aborted (with -EIO reported to userspace) if set.
         *
         * #I915_WEDGED_ON_INIT - If we fail to initialize the GPU we can no
         * longer use the GPU - similar to #I915_WEDGED bit. The difference in
         * the way we're handling "forced" unwedged (e.g. through debugfs),
         * which is not allowed in case we failed to initialize.
         *
         * #I915_WEDGED_ON_FINI - Similar to #I915_WEDGED_ON_INIT, except we
         * use it to mark that the GPU is no longer available (and prevent
         * users from using it).
         */
        unsigned long flags;
#define I915_RESET_BACKOFF      0
#define I915_RESET_ENGINE       1
#define I915_WEDGED_ON_INIT     (BITS_PER_LONG - 3)
#define I915_WEDGED_ON_FINI     (BITS_PER_LONG - 2)
#define I915_WEDGED             (BITS_PER_LONG - 1)

        struct mutex mutex; /* serialises wedging/unwedging */

        /**
         * Waitqueue to signal when the reset has completed. Used by clients
         * that wait for i915->mm.wedged to settle.
         */
        wait_queue_head_t queue;

        struct srcu_struct backoff_srcu;
};

#endif /* _INTEL_RESET_TYPES_H_ */