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 50 static void interrupt_wq(struct work_struct *); 51 52 int 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 86 void 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 */ 112 bool 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 */ 131 static 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 } 142 143 static 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 } 158 159 bool 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 } 171