// Copyright 2016 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <zircon/assert.h>
#include <zircon/process.h>
#include <zircon/syscalls.h>

#include <ddk/debug.h>
#include <ddk/driver.h>
#include <ddk/io-buffer.h>

// Returns true if a buffer with these parameters was allocated using
// zx_vmo_create_contiguous.  This is primarily important so we know whether we
// need to call COMMIT on it to get the pages to exist.
static bool is_allocated_contiguous(size_t size, uint32_t flags) {
  return (flags & IO_BUFFER_CONTIG) && size > PAGE_SIZE;
}

static zx_status_t pin_contig_buffer(zx_handle_t bti, zx_handle_t vmo, size_t size,
                                     zx_paddr_t* phys, zx_handle_t* pmt) {
  uint32_t options = ZX_BTI_PERM_READ | ZX_BTI_PERM_WRITE;
  if (size > PAGE_SIZE) {
    options |= ZX_BTI_CONTIGUOUS;
  }
  return zx_bti_pin(bti, options, vmo, 0, ROUNDUP(size, PAGE_SIZE), phys, 1, pmt);
}

static zx_status_t io_buffer_init_common(io_buffer_t* buffer, zx_handle_t bti_handle,
                                         zx_handle_t vmo_handle, size_t size, zx_off_t offset,
                                         uint32_t flags) {
  zx_vaddr_t virt;

  zx_vm_option_t map_options = ZX_VM_PERM_READ;
  if (flags & IO_BUFFER_RW) {
    map_options = ZX_VM_PERM_READ | ZX_VM_PERM_WRITE;
  }

  zx_status_t status = zx_vmar_map(zx_vmar_root_self(), map_options, 0, vmo_handle, 0, size, &virt);
  if (status != ZX_OK) {
    zxlogf(ERROR, "io_buffer: zx_vmar_map failed %d size: %zu\n", status, size);
    zx_handle_close(vmo_handle);
    return status;
  }

  // For contiguous buffers, pre-lookup the physical mapping so
  // io_buffer_phys() works.  For non-contiguous buffers, io_buffer_physmap()
  // will need to be called.
  zx_paddr_t phys = IO_BUFFER_INVALID_PHYS;
  zx_handle_t pmt_handle = ZX_HANDLE_INVALID;
  if (flags & IO_BUFFER_CONTIG) {
    ZX_DEBUG_ASSERT(offset == 0);
    status = pin_contig_buffer(bti_handle, vmo_handle, size, &phys, &pmt_handle);
    if (status != ZX_OK) {
      zxlogf(ERROR, "io_buffer: init pin failed %d size: %zu\n", status, size);
      zx_vmar_unmap(zx_vmar_root_self(), virt, size);
      zx_handle_close(vmo_handle);
      return status;
    }
  }

  buffer->bti_handle = bti_handle;
  buffer->vmo_handle = vmo_handle;
  buffer->pmt_handle = pmt_handle;
  buffer->size = size;
  buffer->offset = offset;
  buffer->virt = (void*)virt;
  buffer->phys = phys;

  return ZX_OK;
}

zx_status_t io_buffer_init_aligned(io_buffer_t* buffer, zx_handle_t bti, size_t size,
                                   uint32_t alignment_log2, uint32_t flags) {
  memset(buffer, 0, sizeof(*buffer));

  if (size == 0) {
    return ZX_ERR_INVALID_ARGS;
  }
  if (flags & ~IO_BUFFER_FLAGS_MASK) {
    return ZX_ERR_INVALID_ARGS;
  }

  zx_handle_t vmo_handle;
  zx_status_t status;

  if (is_allocated_contiguous(size, flags)) {
    status = zx_vmo_create_contiguous(bti, size, alignment_log2, &vmo_handle);
  } else {
    // zx_vmo_create doesn't support passing an alignment.
    if (alignment_log2 != 0)
      return ZX_ERR_INVALID_ARGS;
    status = zx_vmo_create(size, 0, &vmo_handle);
  }
  if (status != ZX_OK) {
    zxlogf(ERROR, "io_buffer: zx_vmo_create failed %d\n", status);
    return status;
  }

  if (flags & IO_BUFFER_UNCACHED) {
    status = zx_vmo_set_cache_policy(vmo_handle, ZX_CACHE_POLICY_UNCACHED);
    if (status != ZX_OK) {
      zxlogf(ERROR, "io_buffer: zx_vmo_set_cache_policy failed %d\n", status);
      zx_handle_close(vmo_handle);
      return status;
    }
  }

  return io_buffer_init_common(buffer, bti, vmo_handle, size, 0, flags);
}

zx_status_t io_buffer_init(io_buffer_t* buffer, zx_handle_t bti, size_t size, uint32_t flags) {
  // A zero alignment gets interpreted as PAGE_SIZE_SHIFT.
  return io_buffer_init_aligned(buffer, bti, size, 0, flags);
}

zx_status_t io_buffer_init_vmo(io_buffer_t* buffer, zx_handle_t bti, zx_handle_t vmo_handle,
                               zx_off_t offset, uint32_t flags) {
  memset(buffer, 0, sizeof(*buffer));

  if (flags != IO_BUFFER_RO && flags != IO_BUFFER_RW) {
    return ZX_ERR_INVALID_ARGS;
  }

  zx_status_t status = zx_handle_duplicate(vmo_handle, ZX_RIGHT_SAME_RIGHTS, &vmo_handle);
  if (status != ZX_OK)
    return status;

  uint64_t size;
  status = zx_vmo_get_size(vmo_handle, &size);
  if (status != ZX_OK) {
    zx_handle_close(vmo_handle);
    return status;
  }

  return io_buffer_init_common(buffer, bti, vmo_handle, size, offset, flags);
}

void io_buffer_release(io_buffer_t* buffer) {
  if (buffer->vmo_handle != ZX_HANDLE_INVALID) {
    if (buffer->pmt_handle != ZX_HANDLE_INVALID) {
      zx_status_t status = zx_pmt_unpin(buffer->pmt_handle);
      ZX_DEBUG_ASSERT(status == ZX_OK);
      buffer->pmt_handle = ZX_HANDLE_INVALID;
    }

    zx_vmar_unmap(zx_vmar_root_self(), (uintptr_t)buffer->virt, buffer->size);
    zx_handle_close(buffer->vmo_handle);
    buffer->vmo_handle = ZX_HANDLE_INVALID;
  }
  if (buffer->phys_list && buffer->pmt_handle != ZX_HANDLE_INVALID) {
    zx_status_t status = zx_pmt_unpin(buffer->pmt_handle);
    ZX_DEBUG_ASSERT(status == ZX_OK);
    buffer->pmt_handle = ZX_HANDLE_INVALID;
  }
  free(buffer->phys_list);
  buffer->phys_list = NULL;
  buffer->phys = 0;
  buffer->phys_count = 0;
}

zx_status_t io_buffer_cache_op(io_buffer_t* buffer, const uint32_t op, const zx_off_t offset,
                               const size_t size) {
  if (size > 0) {
    return zx_vmo_op_range(buffer->vmo_handle, op, buffer->offset + offset, size, NULL, 0);
  } else {
    return ZX_OK;
  }
}

zx_status_t io_buffer_cache_flush(io_buffer_t* buffer, zx_off_t offset, size_t length) {
  if (offset + length < offset || offset + length > buffer->size) {
    return ZX_ERR_OUT_OF_RANGE;
  }
  return zx_cache_flush(io_buffer_virt(buffer) + offset, length, ZX_CACHE_FLUSH_DATA);
}

zx_status_t io_buffer_cache_flush_invalidate(io_buffer_t* buffer, zx_off_t offset, size_t length) {
  if (offset + length < offset || offset + length > buffer->size) {
    return ZX_ERR_OUT_OF_RANGE;
  }
  return zx_cache_flush(io_buffer_virt(buffer) + offset, length,
                        ZX_CACHE_FLUSH_DATA | ZX_CACHE_FLUSH_INVALIDATE);
}

zx_status_t io_buffer_physmap(io_buffer_t* buffer) {
  if (buffer->phys_count > 0) {
    return ZX_OK;
  }
  if (buffer->size == 0) {
    return ZX_ERR_INVALID_ARGS;
  }
  if (buffer->pmt_handle != ZX_HANDLE_INVALID && buffer->phys == IO_BUFFER_INVALID_PHYS) {
    return ZX_ERR_BAD_STATE;
  }

  // zx_bti_pin returns whole pages, so take into account unaligned vmo
  // offset and length when calculating the amount of pages returned
  uint64_t page_offset = ROUNDDOWN(buffer->offset, PAGE_SIZE);
  // The buffer size is the vmo size from offset 0.
  uint64_t page_length = buffer->size - page_offset;
  uint64_t pages = ROUNDUP(page_length, PAGE_SIZE) / PAGE_SIZE;

  zx_paddr_t* paddrs = malloc(pages * sizeof(zx_paddr_t));
  if (paddrs == NULL) {
    zxlogf(ERROR, "io_buffer: out of memory\n");
    return ZX_ERR_NO_MEMORY;
  }

  if (buffer->phys == IO_BUFFER_INVALID_PHYS) {
    zx_handle_t pmt;
    zx_status_t status =
        io_buffer_physmap_range(buffer, page_offset, page_length, pages, paddrs, &pmt);
    if (status != ZX_OK) {
      free(paddrs);
      return status;
    }
    buffer->pmt_handle = pmt;
  } else {
    // If this is a contiguous io-buffer, just populate the page array
    // ourselves.
    for (size_t i = 0; i < pages; ++i) {
      paddrs[i] = buffer->phys + page_offset + i * PAGE_SIZE;
    }
    paddrs[0] += buffer->offset & (PAGE_SIZE - 1);
  }
  buffer->phys_list = paddrs;
  buffer->phys_count = pages;
  return ZX_OK;
}

zx_status_t io_buffer_physmap_range(io_buffer_t* buffer, zx_off_t offset, size_t length,
                                    size_t phys_count, zx_paddr_t* physmap, zx_handle_t* pmt) {
  // TODO(teisenbe): We need to figure out how to integrate lifetime
  // management of this pin into the io_buffer API...
  const size_t sub_offset = offset & (PAGE_SIZE - 1);
  const size_t pin_offset = offset - sub_offset;
  const size_t pin_length = ROUNDUP(length + sub_offset, PAGE_SIZE);

  if (pin_length / PAGE_SIZE != phys_count) {
    return ZX_ERR_INVALID_ARGS;
  }

  uint32_t options = ZX_BTI_PERM_READ | ZX_BTI_PERM_WRITE;
  zx_status_t status = zx_bti_pin(buffer->bti_handle, options, buffer->vmo_handle, pin_offset,
                                  pin_length, physmap, phys_count, pmt);
  if (status != ZX_OK) {
    return status;
  }
  // Account for the initial misalignment if any
  physmap[0] += sub_offset;
  return ZX_OK;
}