| 1 | /* SPDX-License-Identifier: MIT */ |
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| 2 | /* |
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| 3 | * Copyright © 2019 Intel Corporation |
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| 4 | */ |
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| 5 | |
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| 6 | #ifndef __INTEL_BREADCRUMBS_TYPES__ |
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| 7 | #define __INTEL_BREADCRUMBS_TYPES__ |
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| 8 | |
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| 9 | #include <linux/irq_work.h> |
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| 10 | #include <linux/kref.h> |
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| 11 | #include <linux/list.h> |
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| 12 | #include <linux/spinlock.h> |
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| 13 | #include <linux/types.h> |
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| 14 | |
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| 15 | #include "intel_engine_types.h" |
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| 16 | #include "intel_wakeref.h" |
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| 17 | |
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| 18 | /* |
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| 19 | * Rather than have every client wait upon all user interrupts, |
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| 20 | * with the herd waking after every interrupt and each doing the |
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| 21 | * heavyweight seqno dance, we delegate the task (of being the |
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| 22 | * bottom-half of the user interrupt) to the first client. After |
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| 23 | * every interrupt, we wake up one client, who does the heavyweight |
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| 24 | * coherent seqno read and either goes back to sleep (if incomplete), |
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| 25 | * or wakes up all the completed clients in parallel, before then |
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| 26 | * transferring the bottom-half status to the next client in the queue. |
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| 27 | * |
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| 28 | * Compared to walking the entire list of waiters in a single dedicated |
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| 29 | * bottom-half, we reduce the latency of the first waiter by avoiding |
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| 30 | * a context switch, but incur additional coherent seqno reads when |
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| 31 | * following the chain of request breadcrumbs. Since it is most likely |
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| 32 | * that we have a single client waiting on each seqno, then reducing |
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| 33 | * the overhead of waking that client is much preferred. |
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| 34 | */ |
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| 35 | struct intel_breadcrumbs { |
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| 36 | struct kref ref; |
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| 37 | atomic_t active; |
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| 38 | |
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| 39 | spinlock_t signalers_lock; /* protects the list of signalers */ |
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| 40 | struct list_head signalers; |
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| 41 | struct llist_head signaled_requests; |
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| 42 | atomic_t signaler_active; |
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| 43 | |
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| 44 | spinlock_t irq_lock; /* protects the interrupt from hardirq context */ |
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| 45 | struct irq_work irq_work; /* for use from inside irq_lock */ |
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| 46 | unsigned int irq_enabled; |
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| 47 | intel_wakeref_t irq_armed; |
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| 48 | |
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| 49 | /* Not all breadcrumbs are attached to physical HW */ |
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| 50 | intel_engine_mask_t engine_mask; |
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| 51 | struct intel_engine_cs *irq_engine; |
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| 52 | bool (*irq_enable)(struct intel_breadcrumbs *b); |
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| 53 | void (*irq_disable)(struct intel_breadcrumbs *b); |
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| 54 | }; |
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| 55 | |
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| 56 | #endif /* __INTEL_BREADCRUMBS_TYPES__ */ |
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| 57 | |
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