/*	$NetBSD: kfd_doorbell.c,v 1.2 2018/08/27 04:58:20 riastradh Exp $	*/

/*
 * 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 <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: kfd_doorbell.c,v 1.2 2018/08/27 04:58:20 riastradh Exp $");

#include "kfd_priv.h"
#include <linux/mm.h>
#include <linux/mman.h>
#include <linux/slab.h>
#include <linux/io.h>

/*
 * This extension supports a kernel level doorbells management for
 * the kernel queues.
 * Basically the last doorbells page is devoted to kernel queues
 * and that's assures that any user process won't get access to the
 * kernel doorbells page
 */

#define KERNEL_DOORBELL_PASID 1
#define KFD_SIZE_OF_DOORBELL_IN_BYTES 4

/*
 * Each device exposes a doorbell aperture, a PCI MMIO aperture that
 * receives 32-bit writes that are passed to queues as wptr values.
 * The doorbells are intended to be written by applications as part
 * of queueing work on user-mode queues.
 * We assign doorbells to applications in PAGE_SIZE-sized and aligned chunks.
 * We map the doorbell address space into user-mode when a process creates
 * its first queue on each device.
 * Although the mapping is done by KFD, it is equivalent to an mmap of
 * the /dev/kfd with the particular device encoded in the mmap offset.
 * There will be other uses for mmap of /dev/kfd, so only a range of
 * offsets (KFD_MMAP_DOORBELL_START-END) is used for doorbells.
 */

/* # of doorbell bytes allocated for each process. */
static inline size_t doorbell_process_allocation(void)
{
	return roundup(KFD_SIZE_OF_DOORBELL_IN_BYTES *
			KFD_MAX_NUM_OF_QUEUES_PER_PROCESS,
			PAGE_SIZE);
}

/* Doorbell calculations for device init. */
void kfd_doorbell_init(struct kfd_dev *kfd)
{
	size_t doorbell_start_offset;
	size_t doorbell_aperture_size;
	size_t doorbell_process_limit;

	/*
	 * We start with calculations in bytes because the input data might
	 * only be byte-aligned.
	 * Only after we have done the rounding can we assume any alignment.
	 */

	doorbell_start_offset =
			roundup(kfd->shared_resources.doorbell_start_offset,
					doorbell_process_allocation());

	doorbell_aperture_size =
			rounddown(kfd->shared_resources.doorbell_aperture_size,
					doorbell_process_allocation());

	if (doorbell_aperture_size > doorbell_start_offset)
		doorbell_process_limit =
			(doorbell_aperture_size - doorbell_start_offset) /
						doorbell_process_allocation();
	else
		doorbell_process_limit = 0;

	kfd->doorbell_base = kfd->shared_resources.doorbell_physical_address +
				doorbell_start_offset;

	kfd->doorbell_id_offset = doorbell_start_offset / sizeof(u32);
	kfd->doorbell_process_limit = doorbell_process_limit - 1;

	kfd->doorbell_kernel_ptr = ioremap(kfd->doorbell_base,
						doorbell_process_allocation());

	BUG_ON(!kfd->doorbell_kernel_ptr);

	pr_debug("kfd: doorbell initialization:\n");
	pr_debug("kfd: doorbell base           == 0x%08lX\n",
			(uintptr_t)kfd->doorbell_base);

	pr_debug("kfd: doorbell_id_offset      == 0x%08lX\n",
			kfd->doorbell_id_offset);

	pr_debug("kfd: doorbell_process_limit  == 0x%08lX\n",
			doorbell_process_limit);

	pr_debug("kfd: doorbell_kernel_offset  == 0x%08lX\n",
			(uintptr_t)kfd->doorbell_base);

	pr_debug("kfd: doorbell aperture size  == 0x%08lX\n",
			kfd->shared_resources.doorbell_aperture_size);

	pr_debug("kfd: doorbell kernel address == 0x%08lX\n",
			(uintptr_t)kfd->doorbell_kernel_ptr);
}

int kfd_doorbell_mmap(struct kfd_process *process, struct vm_area_struct *vma)
{
	phys_addr_t address;
	struct kfd_dev *dev;

	/*
	 * For simplicitly we only allow mapping of the entire doorbell
	 * allocation of a single device & process.
	 */
	if (vma->vm_end - vma->vm_start != doorbell_process_allocation())
		return -EINVAL;

	/* Find kfd device according to gpu id */
	dev = kfd_device_by_id(vma->vm_pgoff);
	if (dev == NULL)
		return -EINVAL;

	/* Calculate physical address of doorbell */
	address = kfd_get_process_doorbells(dev, process);

	vma->vm_flags |= VM_IO | VM_DONTCOPY | VM_DONTEXPAND | VM_NORESERVE |
				VM_DONTDUMP | VM_PFNMAP;

	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);

	pr_debug("mapping doorbell page:\n");
	pr_debug("     target user address == 0x%08llX\n",
			(unsigned long long) vma->vm_start);
	pr_debug("     physical address    == 0x%08llX\n", address);
	pr_debug("     vm_flags            == 0x%04lX\n", vma->vm_flags);
	pr_debug("     size                == 0x%04lX\n",
			 doorbell_process_allocation());

	return io_remap_pfn_range(vma,
				vma->vm_start,
				address >> PAGE_SHIFT,
				doorbell_process_allocation(),
				vma->vm_page_prot);
}


/* get kernel iomem pointer for a doorbell */
u32 __iomem *kfd_get_kernel_doorbell(struct kfd_dev *kfd,
					unsigned int *doorbell_off)
{
	u32 inx;

	BUG_ON(!kfd || !doorbell_off);

	mutex_lock(&kfd->doorbell_mutex);
	inx = find_first_zero_bit(kfd->doorbell_available_index,
					KFD_MAX_NUM_OF_QUEUES_PER_PROCESS);

	__set_bit(inx, kfd->doorbell_available_index);
	mutex_unlock(&kfd->doorbell_mutex);

	if (inx >= KFD_MAX_NUM_OF_QUEUES_PER_PROCESS)
		return NULL;

	/*
	 * Calculating the kernel doorbell offset using "faked" kernel
	 * pasid that allocated for kernel queues only
	 */
	*doorbell_off = KERNEL_DOORBELL_PASID * (doorbell_process_allocation() /
							sizeof(u32)) + inx;

	pr_debug("kfd: get kernel queue doorbell\n"
			 "     doorbell offset   == 0x%08d\n"
			 "     kernel address    == 0x%08lX\n",
		*doorbell_off, (uintptr_t)(kfd->doorbell_kernel_ptr + inx));

	return kfd->doorbell_kernel_ptr + inx;
}

void kfd_release_kernel_doorbell(struct kfd_dev *kfd, u32 __iomem *db_addr)
{
	unsigned int inx;

	BUG_ON(!kfd || !db_addr);

	inx = (unsigned int)(db_addr - kfd->doorbell_kernel_ptr);

	mutex_lock(&kfd->doorbell_mutex);
	__clear_bit(inx, kfd->doorbell_available_index);
	mutex_unlock(&kfd->doorbell_mutex);
}

inline void write_kernel_doorbell(u32 __iomem *db, u32 value)
{
	if (db) {
		writel(value, db);
		pr_debug("writing %d to doorbell address 0x%p\n", value, db);
	}
}

/*
 * queue_ids are in the range [0,MAX_PROCESS_QUEUES) and are mapped 1:1
 * to doorbells with the process's doorbell page
 */
unsigned int kfd_queue_id_to_doorbell(struct kfd_dev *kfd,
					struct kfd_process *process,
					unsigned int queue_id)
{
	/*
	 * doorbell_id_offset accounts for doorbells taken by KGD.
	 * pasid * doorbell_process_allocation/sizeof(u32) adjusts
	 * to the process's doorbells
	 */
	return kfd->doorbell_id_offset +
		process->pasid * (doorbell_process_allocation()/sizeof(u32)) +
		queue_id;
}

uint64_t kfd_get_number_elems(struct kfd_dev *kfd)
{
	uint64_t num_of_elems = (kfd->shared_resources.doorbell_aperture_size -
				kfd->shared_resources.doorbell_start_offset) /
					doorbell_process_allocation() + 1;

	return num_of_elems;

}

phys_addr_t kfd_get_process_doorbells(struct kfd_dev *dev,
					struct kfd_process *process)
{
	return dev->doorbell_base +
		process->pasid * doorbell_process_allocation();
}