1/*
2 * Copyright 2014 Advanced Micro Devices, Inc.
3 *
4 * Permission is hereby granted, free of charge, to any person obtaining a
5 * copy of this software and associated documentation files (the "Software"),
6 * to deal in the Software without restriction, including without limitation
7 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
8 * and/or sell copies of the Software, and to permit persons to whom the
9 * Software is furnished to do so, subject to the following conditions:
10 *
11 * The above copyright notice and this permission notice shall be included in
12 * all copies or substantial portions of the Software.
13 *
14 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
15 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
16 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
17 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
18 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
19 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
20 * OTHER DEALINGS IN THE SOFTWARE.
21 */
22
23/*
24 * KFD Interrupts.
25 *
26 * AMD GPUs deliver interrupts by pushing an interrupt description onto the
27 * interrupt ring and then sending an interrupt. KGD receives the interrupt
28 * in ISR and sends us a pointer to each new entry on the interrupt ring.
29 *
30 * We generally can't process interrupt-signaled events from ISR, so we call
31 * out to each interrupt client module (currently only the scheduler) to ask if
32 * each interrupt is interesting. If they return true, then it requires further
33 * processing so we copy it to an internal interrupt ring and call each
34 * interrupt client again from a work-queue.
35 *
36 * There's no acknowledgment for the interrupts we use. The hardware simply
37 * queues a new interrupt each time without waiting.
38 *
39 * The fixed-size internal queue means that it's possible for us to lose
40 * interrupts because we have no back-pressure to the hardware.
41 */
42
43#include <linux/slab.h>
44#include <linux/device.h>
45#include <linux/kfifo.h>
46#include "kfd_priv.h"
47
48#define KFD_IH_NUM_ENTRIES 8192
49
50static void interrupt_wq(struct work_struct *);
51
52int kfd_interrupt_init(struct kfd_dev *kfd)
53{
54 int r;
55
56 r = kfifo_alloc(&kfd->ih_fifo,
57 KFD_IH_NUM_ENTRIES * kfd->device_info->ih_ring_entry_size,
58 GFP_KERNEL);
59 if (r) {
60 dev_err(kfd_chardev(), "Failed to allocate IH fifo\n");
61 return r;
62 }
63
64 kfd->ih_wq = alloc_workqueue("KFD IH", WQ_HIGHPRI, 1);
65 spin_lock_init(&kfd->interrupt_lock);
66
67 INIT_WORK(&kfd->interrupt_work, interrupt_wq);
68
69 kfd->interrupts_active = true;
70
71 /*
72 * After this function returns, the interrupt will be enabled. This
73 * barrier ensures that the interrupt running on a different processor
74 * sees all the above writes.
75 */
76 smp_wmb();
77
78 return 0;
79}
80
81void kfd_interrupt_exit(struct kfd_dev *kfd)
82{
83 /*
84 * Stop the interrupt handler from writing to the ring and scheduling
85 * workqueue items. The spinlock ensures that any interrupt running
86 * after we have unlocked sees interrupts_active = false.
87 */
88 unsigned long flags;
89
90 spin_lock_irqsave(&kfd->interrupt_lock, flags);
91 kfd->interrupts_active = false;
92 spin_unlock_irqrestore(&kfd->interrupt_lock, flags);
93
94 /*
95 * flush_work ensures that there are no outstanding
96 * work-queue items that will access interrupt_ring. New work items
97 * can't be created because we stopped interrupt handling above.
98 */
99 flush_workqueue(kfd->ih_wq);
100
101 kfifo_free(&kfd->ih_fifo);
102}
103
104/*
105 * Assumption: single reader/writer. This function is not re-entrant
106 */
107bool enqueue_ih_ring_entry(struct kfd_dev *kfd, const void *ih_ring_entry)
108{
109 int count;
110
111 count = kfifo_in(&kfd->ih_fifo, ih_ring_entry,
112 kfd->device_info->ih_ring_entry_size);
113 if (count != kfd->device_info->ih_ring_entry_size) {
114 dev_err_ratelimited(kfd_chardev(),
115 "Interrupt ring overflow, dropping interrupt %d\n",
116 count);
117 return false;
118 }
119
120 return true;
121}
122
123/*
124 * Assumption: single reader/writer. This function is not re-entrant
125 */
126static bool dequeue_ih_ring_entry(struct kfd_dev *kfd, void *ih_ring_entry)
127{
128 int count;
129
130 count = kfifo_out(&kfd->ih_fifo, ih_ring_entry,
131 kfd->device_info->ih_ring_entry_size);
132
133 WARN_ON(count && count != kfd->device_info->ih_ring_entry_size);
134
135 return count == kfd->device_info->ih_ring_entry_size;
136}
137
138static void interrupt_wq(struct work_struct *work)
139{
140 struct kfd_dev *dev = container_of(work, struct kfd_dev,
141 interrupt_work);
142 uint32_t ih_ring_entry[KFD_MAX_RING_ENTRY_SIZE];
143
144 if (dev->device_info->ih_ring_entry_size > sizeof(ih_ring_entry)) {
145 dev_err_once(kfd_chardev(), "Ring entry too small\n");
146 return;
147 }
148
149 while (dequeue_ih_ring_entry(dev, ih_ring_entry))
150 dev->device_info->event_interrupt_class->interrupt_wq(dev,
151 ih_ring_entry);
152}
153
154bool interrupt_is_wanted(struct kfd_dev *dev,
155 const uint32_t *ih_ring_entry,
156 uint32_t *patched_ihre, bool *flag)
157{
158 /* integer and bitwise OR so there is no boolean short-circuiting */
159 unsigned int wanted = 0;
160
161 wanted |= dev->device_info->event_interrupt_class->interrupt_isr(dev,
162 ih_ring_entry, patched_ihre, flag);
163
164 return wanted != 0;
165}
166