diff options
Diffstat (limited to 'drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c')
-rw-r--r-- | drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c | 181 |
1 files changed, 181 insertions, 0 deletions
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c b/drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c new file mode 100644 index 0000000..5383dd0 --- /dev/null +++ b/drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c @@ -0,0 +1,181 @@ +/* + * Copyright 2014 Advanced Micro Devices, Inc. + * + * Permission is hereby granted, free of charge, to any person obtaining a + * copy of this software and associated documentation files (the "Software"), + * to deal in the Software without restriction, including without limitation + * the rights to use, copy, modify, merge, publish, distribute, sublicense, + * and/or sell copies of the Software, and to permit persons to whom the + * Software is furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be included in + * all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL + * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR + * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, + * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR + * OTHER DEALINGS IN THE SOFTWARE. + */ + +/* + * KFD Interrupts. + * + * AMD GPUs deliver interrupts by pushing an interrupt description onto the + * interrupt ring and then sending an interrupt. KGD receives the interrupt + * in ISR and sends us a pointer to each new entry on the interrupt ring. + * + * We generally can't process interrupt-signaled events from ISR, so we call + * out to each interrupt client module (currently only the scheduler) to ask if + * each interrupt is interesting. If they return true, then it requires further + * processing so we copy it to an internal interrupt ring and call each + * interrupt client again from a work-queue. + * + * There's no acknowledgment for the interrupts we use. The hardware simply + * queues a new interrupt each time without waiting. + * + * The fixed-size internal queue means that it's possible for us to lose + * interrupts because we have no back-pressure to the hardware. + */ + +#include <linux/slab.h> +#include <linux/device.h> +#include "kfd_priv.h" + +#define KFD_INTERRUPT_RING_SIZE 1024 + +static void interrupt_wq(struct work_struct *); + +int kfd_interrupt_init(struct kfd_dev *kfd) +{ + void *interrupt_ring = kmalloc_array(KFD_INTERRUPT_RING_SIZE, + kfd->device_info->ih_ring_entry_size, + GFP_KERNEL); + if (!interrupt_ring) + return -ENOMEM; + + kfd->interrupt_ring = interrupt_ring; + kfd->interrupt_ring_size = + KFD_INTERRUPT_RING_SIZE * kfd->device_info->ih_ring_entry_size; + atomic_set(&kfd->interrupt_ring_wptr, 0); + atomic_set(&kfd->interrupt_ring_rptr, 0); + + spin_lock_init(&kfd->interrupt_lock); + + INIT_WORK(&kfd->interrupt_work, interrupt_wq); + + kfd->interrupts_active = true; + + /* + * After this function returns, the interrupt will be enabled. This + * barrier ensures that the interrupt running on a different processor + * sees all the above writes. + */ + smp_wmb(); + + return 0; +} + +void kfd_interrupt_exit(struct kfd_dev *kfd) +{ + /* + * Stop the interrupt handler from writing to the ring and scheduling + * workqueue items. The spinlock ensures that any interrupt running + * after we have unlocked sees interrupts_active = false. + */ + unsigned long flags; + + spin_lock_irqsave(&kfd->interrupt_lock, flags); + kfd->interrupts_active = false; + spin_unlock_irqrestore(&kfd->interrupt_lock, flags); + + /* + * Flush_scheduled_work ensures that there are no outstanding + * work-queue items that will access interrupt_ring. New work items + * can't be created because we stopped interrupt handling above. + */ + flush_scheduled_work(); + + kfree(kfd->interrupt_ring); +} + +/* + * This assumes that it can't be called concurrently with itself + * but only with dequeue_ih_ring_entry. + */ +bool enqueue_ih_ring_entry(struct kfd_dev *kfd, const void *ih_ring_entry) +{ + unsigned int rptr = atomic_read(&kfd->interrupt_ring_rptr); + unsigned int wptr = atomic_read(&kfd->interrupt_ring_wptr); + + if ((rptr - wptr) % kfd->interrupt_ring_size == + kfd->device_info->ih_ring_entry_size) { + /* This is very bad, the system is likely to hang. */ + dev_err_ratelimited(kfd_chardev(), + "Interrupt ring overflow, dropping interrupt.\n"); + return false; + } + + memcpy(kfd->interrupt_ring + wptr, ih_ring_entry, + kfd->device_info->ih_ring_entry_size); + + wptr = (wptr + kfd->device_info->ih_ring_entry_size) % + kfd->interrupt_ring_size; + smp_wmb(); /* Ensure memcpy'd data is visible before wptr update. */ + atomic_set(&kfd->interrupt_ring_wptr, wptr); + + return true; +} + +/* + * This assumes that it can't be called concurrently with itself + * but only with enqueue_ih_ring_entry. + */ +static bool dequeue_ih_ring_entry(struct kfd_dev *kfd, void *ih_ring_entry) +{ + /* + * Assume that wait queues have an implicit barrier, i.e. anything that + * happened in the ISR before it queued work is visible. + */ + + unsigned int wptr = atomic_read(&kfd->interrupt_ring_wptr); + unsigned int rptr = atomic_read(&kfd->interrupt_ring_rptr); + + if (rptr == wptr) + return false; + + memcpy(ih_ring_entry, kfd->interrupt_ring + rptr, + kfd->device_info->ih_ring_entry_size); + + rptr = (rptr + kfd->device_info->ih_ring_entry_size) % + kfd->interrupt_ring_size; + + /* + * Ensure the rptr write update is not visible until + * memcpy has finished reading. + */ + smp_mb(); + atomic_set(&kfd->interrupt_ring_rptr, rptr); + + return true; +} + +static void interrupt_wq(struct work_struct *work) +{ + struct kfd_dev *dev = container_of(work, struct kfd_dev, + interrupt_work); + + uint32_t ih_ring_entry[DIV_ROUND_UP( + dev->device_info->ih_ring_entry_size, + sizeof(uint32_t))]; + + while (dequeue_ih_ring_entry(dev, ih_ring_entry)) + ; +} + +bool interrupt_is_wanted(struct kfd_dev *dev, const uint32_t *ih_ring_entry) +{ + return false; +} |