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	if (unlikely(!kfd->ih_wq)) {
 66		kfifo_free(&kfd->ih_fifo);
 67		dev_err(kfd_chardev(), "Failed to allocate KFD IH workqueue\n");
 68		return -ENOMEM;
 69	}
 70	spin_lock_init(&kfd->interrupt_lock);
 71
 72	INIT_WORK(&kfd->interrupt_work, interrupt_wq);
 73
 74	kfd->interrupts_active = true;
 75
 76	/*
 77	 * After this function returns, the interrupt will be enabled. This
 78	 * barrier ensures that the interrupt running on a different processor
 79	 * sees all the above writes.
 80	 */
 81	smp_wmb();
 82
 83	return 0;
 84}
 85
 86void kfd_interrupt_exit(struct kfd_dev *kfd)
 87{
 88	/*
 89	 * Stop the interrupt handler from writing to the ring and scheduling
 90	 * workqueue items. The spinlock ensures that any interrupt running
 91	 * after we have unlocked sees interrupts_active = false.
 92	 */
 93	unsigned long flags;
 94
 95	spin_lock_irqsave(&kfd->interrupt_lock, flags);
 96	kfd->interrupts_active = false;
 97	spin_unlock_irqrestore(&kfd->interrupt_lock, flags);
 98
 99	/*
100	 * flush_work ensures that there are no outstanding
101	 * work-queue items that will access interrupt_ring. New work items
102	 * can't be created because we stopped interrupt handling above.
103	 */
104	flush_workqueue(kfd->ih_wq);
105
106	kfifo_free(&kfd->ih_fifo);
107}
108
109/*
110 * Assumption: single reader/writer. This function is not re-entrant
111 */
112bool enqueue_ih_ring_entry(struct kfd_dev *kfd,	const void *ih_ring_entry)
113{
114	int count;
115
116	count = kfifo_in(&kfd->ih_fifo, ih_ring_entry,
117				kfd->device_info->ih_ring_entry_size);
118	if (count != kfd->device_info->ih_ring_entry_size) {
119		dev_err_ratelimited(kfd_chardev(),
120			"Interrupt ring overflow, dropping interrupt %d\n",
121			count);
122		return false;
123	}
124
125	return true;
126}
127
128/*
129 * Assumption: single reader/writer. This function is not re-entrant
130 */
131static bool dequeue_ih_ring_entry(struct kfd_dev *kfd, void *ih_ring_entry)
132{
133	int count;
134
135	count = kfifo_out(&kfd->ih_fifo, ih_ring_entry,
136				kfd->device_info->ih_ring_entry_size);
137
138	WARN_ON(count && count != kfd->device_info->ih_ring_entry_size);
139
140	return count == kfd->device_info->ih_ring_entry_size;
141}
142
143static void interrupt_wq(struct work_struct *work)
144{
145	struct kfd_dev *dev = container_of(work, struct kfd_dev,
146						interrupt_work);
147	uint32_t ih_ring_entry[KFD_MAX_RING_ENTRY_SIZE];
148
149	if (dev->device_info->ih_ring_entry_size > sizeof(ih_ring_entry)) {
150		dev_err_once(kfd_chardev(), "Ring entry too small\n");
151		return;
152	}
153
154	while (dequeue_ih_ring_entry(dev, ih_ring_entry))
155		dev->device_info->event_interrupt_class->interrupt_wq(dev,
156								ih_ring_entry);
157}
158
159bool interrupt_is_wanted(struct kfd_dev *dev,
160			const uint32_t *ih_ring_entry,
161			uint32_t *patched_ihre, bool *flag)
162{
163	/* integer and bitwise OR so there is no boolean short-circuiting */
164	unsigned int wanted = 0;
165
166	wanted |= dev->device_info->event_interrupt_class->interrupt_isr(dev,
167					 ih_ring_entry, patched_ihre, flag);
168
169	return wanted != 0;
170}