/*
* Copyright © 2014 Intel Corporation
*
* 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 (including the next
* paragraph) 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 AUTHORS OR COPYRIGHT HOLDERS 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.
*
*/
#include <linux/circ_buf.h>
#include "i915_drv.h"
#include "intel_uc.h"
#include <trace/events/dma_fence.h>
/**
* DOC: GuC-based command submission
*
* GuC client:
* A i915_guc_client refers to a submission path through GuC. Currently, there
* is only one of these (the execbuf_client) and this one is charged with all
* submissions to the GuC. This struct is the owner of a doorbell, a process
* descriptor and a workqueue (all of them inside a single gem object that
* contains all required pages for these elements).
*
* GuC stage descriptor:
* During initialization, the driver allocates a static pool of 1024 such
* descriptors, and shares them with the GuC.
* Currently, there exists a 1:1 mapping between a i915_guc_client and a
* guc_stage_desc (via the client's stage_id), so effectively only one
* gets used. This stage descriptor lets the GuC know about the doorbell,
* workqueue and process descriptor. Theoretically, it also lets the GuC
* know about our HW contexts (context ID, etc...), but we actually
* employ a kind of submission where the GuC uses the LRCA sent via the work
* item instead (the single guc_stage_desc associated to execbuf client
* contains information about the default kernel context only, but this is
* essentially unused). This is called a "proxy" submission.
*
* The Scratch registers:
* There are 16 MMIO-based registers start from 0xC180. The kernel driver writes
* a value to the action register (SOFT_SCRATCH_0) along with any data. It then
* triggers an interrupt on the GuC via another register write (0xC4C8).
* Firmware writes a success/fail code back to the action register after
* processes the request. The kernel driver polls waiting for this update and
* then proceeds.
* See intel_guc_send()
*
* Doorbells:
* Doorbells are interrupts to uKernel. A doorbell is a single cache line (QW)
* mapped into process space.
*
* Work Items:
* There are several types of work items that the host may place into a
* workqueue, each with its own requirements and limitations. Currently only
* WQ_TYPE_INORDER is needed to support legacy submission via GuC, which
* represents in-order queue. The kernel driver packs ring tail pointer and an
* ELSP context descriptor dword into Work Item.
* See guc_wq_item_append()
*
* ADS:
* The Additional Data Struct (ADS) has pointers for different buffers used by
* the GuC. One single gem object contains the ADS struct itself (guc_ads), the
* scheduling policies (guc_policies), a structure describing a collection of
* register sets (guc_mmio_reg_state) and some extra pages for the GuC to save
* its internal state for sleep.
*
*/
static inline bool is_high_priority(struct i915_guc_client* client)
{
return client->priority <= GUC_CLIENT_PRIORITY_HIGH;
}
static int __reserve_doorbell(struct i915_guc_client *client)
{
unsigned long offset;
unsigned long end;
u16 id;
GEM_BUG_ON(client->doorbell_id != GUC_DOORBELL_INVALID);
/*
* The bitmap tracks which doorbell registers are currently in use.
* It is split into two halves; the first half is used for normal
* priority contexts, the second half for high-priority ones.
*/
offset = 0;
end = GUC_NUM_DOORBELLS/2;
if (is_high_priority(client)) {
offset = end;
end += offset;
}
id = find_next_zero_bit(client->guc->doorbell_bitmap, offset, end);
if (id == end)
return -ENOSPC;
__set_bit(id, client->