/*
 * 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.
 *
 */

#include <linux/dma-mapping.h>

#include "amdgpu.h"
#include "amdgpu_ih.h"

/**
 * amdgpu_ih_ring_init - initialize the IH state
 *
 * @adev: amdgpu_device pointer
 * @ih: ih ring to initialize
 * @ring_size: ring size to allocate
 * @use_bus_addr: true when we can use dma_alloc_coherent
 *
 * Initializes the IH state and allocates a buffer
 * for the IH ring buffer.
 * Returns 0 for success, errors for failure.
 */
int amdgpu_ih_ring_init(struct amdgpu_device *adev, struct amdgpu_ih_ring *ih,
                        unsigned ring_size, bool use_bus_addr)
{
        u32 rb_bufsz;
        int r;

        /* Align ring size */
        rb_bufsz = order_base_2(ring_size / 4);
        ring_size = (1 << rb_bufsz) * 4;
        ih->ring_size = ring_size;
        ih->ptr_mask = ih->ring_size - 1;
        ih->rptr = 0;
        ih->use_bus_addr = use_bus_addr;

        if (use_bus_addr) {
                dma_addr_t dma_addr;

                if (ih->ring)
                        return 0;

                /* add 8 bytes for the rptr/wptr shadows and
                 * add them to the end of the ring allocation.
                 */
                ih->ring = dma_alloc_coherent(adev->dev, ih->ring_size + 8,
                                              &dma_addr, GFP_KERNEL);
                if (ih->ring == NULL)
                        return -ENOMEM;

                ih->gpu_addr = dma_addr;
                ih->wptr_addr = dma_addr + ih->ring_size;
                ih->wptr_cpu = &ih->ring[ih->ring_size / 4];
                ih->rptr_addr = dma_addr + ih->ring_size + 4;
                ih->rptr_cpu = &ih->ring[(ih->ring_size / 4) + 1];
        } else {
                unsigned wptr_offs, rptr_offs;

                r = amdgpu_device_wb_get(adev, &wptr_offs);
                if (r)
                        return r;

                r = amdgpu_device_wb_get(adev, &rptr_offs);
                if (r) {
                        amdgpu_device_wb_free(adev, wptr_offs);
                        return r;
                }

                r = amdgpu_bo_create_kernel(adev, ih->ring_size, PAGE_SIZE,
                                            AMDGPU_GEM_DOMAIN_GTT,
                                            &ih->ring_obj, &ih->gpu_addr,
                                            (void **)&ih->ring);
                if (r) {
                        amdgpu_device_wb_free(adev, rptr_offs);
                        amdgpu_device_wb_free(adev, wptr_offs);
                        return r;
                }

                ih->wptr_addr = adev->wb.gpu_addr + wptr_offs * 4;
                ih->wptr_cpu = &adev->wb.wb[wptr_offs];
                ih->rptr_addr = adev->wb.gpu_addr + rptr_offs * 4;
                ih->rptr_cpu = &adev->wb.wb[rptr_offs];
        }
        return 0;
}

/**
 * amdgpu_ih_ring_fini - tear down the IH state
 *
 * @adev: amdgpu_device pointer
 * @ih: ih ring to tear down
 *
 * Tears down the IH state and frees buffer
 * used for the IH ring buffer.
 */
void amdgpu_ih_ring_fini(struct amdgpu_device *adev, struct amdgpu_ih_ring *ih)
{
        if (ih->use_bus_addr) {
                if (!ih->ring)
                        return;

                /* add 8 bytes for the rptr/wptr shadows and
                 * add them to the end of the ring allocation.
                 */
                dma_free_coherent(adev->dev, ih->ring_size + 8,
                                  (void *)ih->ring, ih->gpu_addr);
                ih->ring = NULL;
        } else {
                amdgpu_bo_free_kernel(&ih->ring_obj, &ih->gpu_addr,
                                      (void **)&ih->ring);
                amdgpu_device_wb_free(adev, (ih->wptr_addr - ih->gpu_addr) / 4);
                amdgpu_device_wb_free(adev, (ih->rptr_addr - ih->gpu_addr) / 4);
        }
}

/**
 * amdgpu_ih_ring_write - write IV to the ring buffer
 *
 * @ih: ih ring to write to
 * @iv: the iv to write
 * @num_dw: size of the iv in dw
 *
 * Writes an IV to the ring buffer using the CPU and increment the wptr.
 * Used for testing and delegating IVs to a software ring.
 */
void amdgpu_ih_ring_write(struct amdgpu_ih_ring *ih, const uint32_t *iv,
                          unsigned int num_dw)
{
        uint32_t wptr = le32_to_cpu(*ih->wptr_cpu) >> 2;
        unsigned int i;

        for (i = 0; i < num_dw; ++i)
                ih->ring[wptr++] = cpu_to_le32(iv[i]);

        wptr <<= 2;
        wptr &= ih->ptr_mask;

        /* Only commit the new wptr if we don't overflow */
        if (wptr != READ_ONCE(ih->rptr)) {
                wmb();
                WRITE_ONCE(*ih->wptr_cpu, cpu_to_le32(wptr));
        }
}

/**
 * amdgpu_ih_process - interrupt handler
 *
 * @adev: amdgpu_device pointer
 * @ih: ih ring to process
 *
 * Interrupt hander (VI), walk the IH ring.
 * Returns irq process return code.
 */
int amdgpu_ih_process(struct amdgpu_device *adev, struct amdgpu_ih_ring *ih)
{
        unsigned int count = AMDGPU_IH_MAX_NUM_IVS;
        u32 wptr;

        if (!ih->enabled || adev->shutdown)
                return IRQ_NONE;

        wptr = amdgpu_ih_get_wptr(adev, ih);

restart_ih:
        /* is somebody else already processing irqs? */
        if (atomic_xchg(&ih->lock, 1))
                return IRQ_NONE;

        DRM_DEBUG("%s: rptr %d, wptr %d\n", __func__, ih->rptr, wptr);

        /* Order reading of wptr vs. reading of IH ring data */
        rmb();

        while (ih->rptr != wptr && --count) {
                amdgpu_irq_dispatch(adev, ih);
                ih->rptr &= ih->ptr_mask;
        }

        amdgpu_ih_set_rptr(adev, ih);
        atomic_set(&ih->lock, 0);

        /* make sure wptr hasn't changed while processing */
        wptr = amdgpu_ih_get_wptr(adev, ih);
        if (wptr != ih->rptr)
                goto restart_ih;

        return IRQ_HANDLED;
}