// 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 <ddk/io-buffer.h>
#include <ddk/debug.h>
#include <ddk/driver.h>
#include <zircon/assert.h>
#include <zircon/process.h>
#include <zircon/syscalls.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.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;
}