/*
 * Copyright © 2018 Broadcom
 *
 * 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.
 */

/** @file
 *
 * Implements core GEM support (particularly ioctls) underneath the libc ioctl
 * wrappers, and calls into the driver-specific code as necessary.
 */

#include <c11/threads.h>
#include <errno.h>
#include <linux/memfd.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <unistd.h>
#include "drm-uapi/drm.h"
#include "drm_shim.h"
#include "util/hash_table.h"
#include "util/u_atomic.h"

static mtx_t handle_lock = _MTX_INITIALIZER_NP;

#ifndef HAVE_MEMFD_CREATE
#include <sys/syscall.h>

static inline int
memfd_create(const char *name, unsigned int flags)
{
   return syscall(SYS_memfd_create, name, flags);
}
#endif

/* Global state for the shim shared between libc, core, and driver. */
struct shim_device shim_device;

static uint32_t
uint_key_hash(const void *key)
{
   return (uintptr_t)key;
}

static bool
uint_key_compare(const void *a, const void *b)
{
   return a == b;
}

/**
 * Called when the first libc shim is called, to initialize GEM simulation
 * state (other than the shims themselves).
 */
void
drm_shim_device_init(void)
{
   shim_device.fd_map = _mesa_hash_table_create(NULL,
                                                uint_key_hash,
                                                uint_key_compare);

   drm_shim_driver_init();
}

static struct shim_fd *
drm_shim_file_create(int fd)
{
   struct shim_fd *shim_fd = calloc(1, sizeof(*shim_fd));

   shim_fd->fd = fd;
   shim_fd->handles = _mesa_hash_table_create(NULL,
                                              uint_key_hash,
                                              uint_key_compare);

   return shim_fd;
}

/**
 * Called when the libc shims have interposed an open or dup of our simulated
 * DRM device.
 */
void drm_shim_fd_register(int fd, struct shim_fd *shim_fd)
{
   if (!shim_fd)
      shim_fd = drm_shim_file_create(fd);

   _mesa_hash_table_insert(shim_device.fd_map, (void *)(uintptr_t)(fd + 1), shim_fd);
}

struct shim_fd *
drm_shim_fd_lookup(int fd)
{
   if (fd == -1)
      return NULL;

   struct hash_entry *entry =
      _mesa_hash_table_search(shim_device.fd_map, (void *)(uintptr_t)(fd + 1));

   if (!entry)
      return NULL;
   return entry->data;
}

/* ioctl used by drmGetVersion() */
static int
drm_shim_ioctl_version(int fd, unsigned long request, void *arg)
{
   struct drm_version *args = arg;
   const char *date = "20190320";
   const char *desc = "shim";

   args->version_major = shim_device.version_major;
   args->version_minor = shim_device.version_minor;
   args->version_patchlevel = shim_device.version_patchlevel;

   if (args->name)
      strncpy(args->name, shim_device.driver_name, args->name_len);
   if (args->date)
      strncpy(args->date, date, args->date_len);
   if (args->desc)
      strncpy(args->desc, desc, args->desc_len);
   args->name_len = strlen(shim_device.driver_name);
   args->date_len = strlen(date);
   args->desc_len = strlen(desc);

   return 0;
}

static int
drm_shim_ioctl_get_cap(int fd, unsigned long request, void *arg)
{
   struct drm_get_cap *gc = arg;

   switch (gc->capability) {
   case DRM_CAP_PRIME:
   case DRM_CAP_SYNCOBJ:
      gc->value = 1;
      return 0;

   default:
      fprintf(stderr, "DRM_IOCTL_GET_CAP: unhandled 0x%x\n",
              (int)gc->capability);
      return -1;
   }
}

static int
drm_shim_ioctl_gem_close(int fd, unsigned long request, void *arg)
{
   struct shim_fd *shim_fd = drm_shim_fd_lookup(fd);
   struct drm_gem_close *c = arg;

   if (!c->handle)
      return 0;

   mtx_lock(&handle_lock);
   struct hash_entry *entry =
      _mesa_hash_table_search(shim_fd->handles, (void *)(uintptr_t)c->handle);
   if (!entry) {
      mtx_unlock(&handle_lock);
      return -EINVAL;
   }

   struct shim_bo *bo = entry->data;
   _mesa_hash_table_remove(shim_fd->handles, entry);
   drm_shim_bo_put(bo);
   mtx_unlock(&handle_lock);
   return 0;
}

static int
drm_shim_ioctl_stub(int fd, unsigned long request, void *arg)
{
   return 0;
}

ioctl_fn_t core_ioctls[] = {
   [_IOC_NR(DRM_IOCTL_VERSION)] = drm_shim_ioctl_version,
   [_IOC_NR(DRM_IOCTL_GET_CAP)] = drm_shim_ioctl_get_cap,
   [_IOC_NR(DRM_IOCTL_GEM_CLOSE)] = drm_shim_ioctl_gem_close,
   [_IOC_NR(DRM_IOCTL_SYNCOBJ_CREATE)] = drm_shim_ioctl_stub,
   [_IOC_NR(DRM_IOCTL_SYNCOBJ_DESTROY)] = drm_shim_ioctl_stub,
   [_IOC_NR(DRM_IOCTL_SYNCOBJ_HANDLE_TO_FD)] = drm_shim_ioctl_stub,
   [_IOC_NR(DRM_IOCTL_SYNCOBJ_FD_TO_HANDLE)] = drm_shim_ioctl_stub,
};

/**
 * Implements the GEM core ioctls, and calls into driver-specific ioctls.
 */
int
drm_shim_ioctl(int fd, unsigned long request, void *arg)
{
   int type = _IOC_TYPE(request);
   int nr = _IOC_NR(request);

   assert(type == DRM_IOCTL_BASE);

   if (nr >= DRM_COMMAND_BASE && nr < DRM_COMMAND_END) {
      int driver_nr = nr - DRM_COMMAND_BASE;

      if (driver_nr < shim_device.driver_ioctl_count &&
          shim_device.driver_ioctls[driver_nr]) {
         return shim_device.driver_ioctls[driver_nr](fd, request, arg);
      }
   } else {
      if (nr < ARRAY_SIZE(core_ioctls) && core_ioctls[nr]) {
         return core_ioctls[nr](fd, request, arg);
      }
   }

   if (nr >= DRM_COMMAND_BASE && nr < DRM_COMMAND_END) {
      fprintf(stderr,
              "DRM_SHIM: unhandled driver DRM ioctl %d (0x%08lx)\n",
              nr - DRM_COMMAND_BASE, request);
   } else {
      fprintf(stderr,
              "DRM_SHIM: unhandled core DRM ioctl 0x%X (0x%08lx)\n",
              nr, request);
   }

   abort();
}

void
drm_shim_bo_init(struct shim_bo *bo, size_t size)
{
   bo->size = size;
   bo->fd = memfd_create("shim bo", MFD_CLOEXEC);
   if (bo->fd == -1) {
      fprintf(stderr, "Failed to create BO: %s\n", strerror(errno));
      abort();
   }

   if (ftruncate(bo->fd, size) == -1) {
      fprintf(stderr, "Failed to size BO: %s\n", strerror(errno));
      abort();
   }
}

struct shim_bo *
drm_shim_bo_lookup(struct shim_fd *shim_fd, int handle)
{
   if (!handle)
      return NULL;

   mtx_lock(&handle_lock);
   struct hash_entry *entry =
      _mesa_hash_table_search(shim_fd->handles, (void *)(uintptr_t)handle);
   struct shim_bo *bo = entry ? entry->data : NULL;
   mtx_unlock(&handle_lock);

   if (bo)
      p_atomic_inc(&bo->refcount);

   return bo;
}

void
drm_shim_bo_get(struct shim_bo *bo)
{
   p_atomic_inc(&bo->refcount);
}

void
drm_shim_bo_put(struct shim_bo *bo)
{
   if (p_atomic_dec_return(&bo->refcount) == 0)
      return;

   if (shim_device.driver_bo_free)
      shim_device.driver_bo_free(bo);
   close(bo->fd);
   free(bo);
}

int
drm_shim_bo_get_handle(struct shim_fd *shim_fd, struct shim_bo *bo)
{
   /* We should probably have some real datastructure for finding the free
    * number.
    */
   mtx_lock(&handle_lock);
   for (int new_handle = 1; ; new_handle++) {
      void *key = (void *)(uintptr_t)new_handle;
      if (!_mesa_hash_table_search(shim_fd->handles, key)) {
         drm_shim_bo_get(bo);
         _mesa_hash_table_insert(shim_fd->handles, key, bo);
         mtx_unlock(&handle_lock);
         return new_handle;
      }
   }
   mtx_unlock(&handle_lock);

   return 0;
}

/* Creates an mmap offset for the BO in the DRM fd.
 *
 * XXX: We should be maintaining a u_mm allocator where the mmap offsets
 * allocate the size of the BO and it can be used to look the BO back up.
 * Instead, we just stuff the shim's pointer as the return value, and treat
 * the incoming mmap offset on the DRM fd as a BO pointer.  This doesn't work
 * if someone tries to map a subset of the BO, but it's enough to get V3D
 * working for now.
 */
uint64_t
drm_shim_bo_get_mmap_offset(struct shim_fd *shim_fd, struct shim_bo *bo)
{
   return (uintptr_t)bo;
}

/* For mmap() on the DRM fd, look up the BO from the "offset" and map the BO's
 * fd.
 */
void *
drm_shim_mmap(struct shim_fd *shim_fd, size_t length, int prot, int flags,
              int fd, off_t offset)
{
   struct shim_bo *bo = (void *)(uintptr_t)offset;

   return mmap(NULL, length, prot, flags, bo->fd, 0);
}