1 files changed, 236 insertions, 0 deletions
diff --git a/render/allocator/gbm.c b/render/allocator/gbm.c
new file mode 100644
index 00000000..ace7ca68
--- /dev/null
+++ b/render/allocator/gbm.c
@@ -0,0 +1,236 @@
+#define _POSIX_C_SOURCE 200809L
+#include <assert.h>
+#include <drm_fourcc.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <wlr/util/log.h>
+#include <xf86drm.h>
+#include "render/allocator/gbm.h"
+
+static const struct wlr_buffer_impl buffer_impl;
+
+static struct wlr_gbm_buffer *get_gbm_buffer_from_buffer(
+		struct wlr_buffer *buffer) {
+	assert(buffer->impl == &buffer_impl);
+	return (struct wlr_gbm_buffer *)buffer;
+}
+
+static bool export_gbm_bo(struct gbm_bo *bo,
+		struct wlr_dmabuf_attributes *out) {
+	struct wlr_dmabuf_attributes attribs = {0};
+
+	attribs.n_planes = gbm_bo_get_plane_count(bo);
+	if (attribs.n_planes > WLR_DMABUF_MAX_PLANES) {
+		wlr_log(WLR_ERROR, "GBM BO contains too many planes (%d)",
+			attribs.n_planes);
+		return false;
+	}
+
+	attribs.width = gbm_bo_get_width(bo);
+	attribs.height = gbm_bo_get_height(bo);
+	attribs.format = gbm_bo_get_format(bo);
+	attribs.modifier = gbm_bo_get_modifier(bo);
+
+	int i;
+	int32_t handle = -1;
+	for (i = 0; i < attribs.n_planes; ++i) {
+#if HAS_GBM_BO_GET_FD_FOR_PLANE
+		attribs.fd[i] = gbm_bo_get_fd_for_plane(bo, i);
+		(void)handle;
+#else
+		// GBM is lacking a function to get a FD for a given plane. Instead,
+		// check all planes have the same handle. We can't use
+		// drmPrimeHandleToFD because that messes up handle ref'counting in
+		// the user-space driver.
+		union gbm_bo_handle plane_handle = gbm_bo_get_handle_for_plane(bo, i);
+		if (plane_handle.s32 < 0) {
+			wlr_log(WLR_ERROR, "gbm_bo_get_handle_for_plane failed");
+			goto error_fd;
+		}
+		if (i == 0) {
+			handle = plane_handle.s32;
+		} else if (plane_handle.s32 != handle) {
+			wlr_log(WLR_ERROR, "Failed to export GBM BO: "
+				"all planes don't have the same GEM handle");
+			goto error_fd;
+		}
+
+		attribs.fd[i] = gbm_bo_get_fd(bo);
+#endif
+
+		if (attribs.fd[i] < 0) {
+			wlr_log(WLR_ERROR, "gbm_bo_get_fd failed");
+			goto error_fd;
+		}
+
+		attribs.offset[i] = gbm_bo_get_offset(bo, i);
+		attribs.stride[i] = gbm_bo_get_stride_for_plane(bo, i);
+	}
+
+	memcpy(out, &attribs, sizeof(attribs));
+	return true;
+
+error_fd:
+	for (int j = 0; j < i; ++j) {
+		close(attribs.fd[j]);
+	}
+	return false;
+}
+
+static struct wlr_gbm_buffer *create_buffer(struct wlr_gbm_allocator *alloc,
+		int width, int height, const struct wlr_drm_format *format) {
+	struct gbm_device *gbm_device = alloc->gbm_device;
+
+	struct gbm_bo *bo = NULL;
+	bool has_modifier = true;
+	if (format->len > 0) {
+		bo = gbm_bo_create_with_modifiers(gbm_device, width, height,
+			format->format, format->modifiers, format->len);
+	}
+	if (bo == NULL) {
+		uint32_t usage = GBM_BO_USE_SCANOUT | GBM_BO_USE_RENDERING;
+		if (format->len == 1 &&
+				format->modifiers[0] == DRM_FORMAT_MOD_LINEAR) {
+			usage |= GBM_BO_USE_LINEAR;
+		}
+		bo = gbm_bo_create(gbm_device, width, height, format->format, usage);
+		has_modifier = false;
+	}
+	if (bo == NULL) {
+		wlr_log(WLR_ERROR, "gbm_bo_create failed");
+		return NULL;
+	}
+
+	struct wlr_gbm_buffer *buffer = calloc(1, sizeof(*buffer));
+	if (buffer == NULL) {
+		gbm_bo_destroy(bo);
+		return NULL;
+	}
+	wlr_buffer_init(&buffer->base, &buffer_impl, width, height);
+	buffer->gbm_bo = bo;
+	wl_list_insert(&alloc->buffers, &buffer->link);
+
+	if (!export_gbm_bo(bo, &buffer->dmabuf)) {
+		free(buffer);
+		gbm_bo_destroy(bo);
+		return NULL;
+	}
+
+	// If the buffer has been allocated with an implicit modifier, make sure we
+	// don't populate the modifier field: other parts of the stack may not
+	// understand modifiers, and they can't strip the modifier.
+	if (!has_modifier) {
+		buffer->dmabuf.modifier = DRM_FORMAT_MOD_INVALID;
+	}
+
+	wlr_log(WLR_DEBUG, "Allocated %dx%d GBM buffer (format 0x%"PRIX32", "
+		"modifier 0x%"PRIX64")", buffer->base.width, buffer->base.height,
+		buffer->dmabuf.format, buffer->dmabuf.modifier);
+
+	return buffer;
+}
+
+static void buffer_destroy(struct wlr_buffer *wlr_buffer) {
+	struct wlr_gbm_buffer *buffer =
+		get_gbm_buffer_from_buffer(wlr_buffer);
+	wlr_dmabuf_attributes_finish(&buffer->dmabuf);
+	if (buffer->gbm_bo != NULL) {
+		gbm_bo_destroy(buffer->gbm_bo);
+	}
+	wl_list_remove(&buffer->link);
+	free(buffer);
+}
+
+static bool buffer_get_dmabuf(struct wlr_buffer *wlr_buffer,
+		struct wlr_dmabuf_attributes *attribs) {
+	struct wlr_gbm_buffer *buffer =
+		get_gbm_buffer_from_buffer(wlr_buffer);
+	memcpy(attribs, &buffer->dmabuf, sizeof(buffer->dmabuf));
+	return true;
+}
+
+static const struct wlr_buffer_impl buffer_impl = {
+	.destroy = buffer_destroy,
+	.get_dmabuf = buffer_get_dmabuf,
+};
+
+static const struct wlr_allocator_interface allocator_impl;
+
+static struct wlr_gbm_allocator *get_gbm_alloc_from_alloc(
+		struct wlr_allocator *alloc) {
+	assert(alloc->impl == &allocator_impl);
+	return (struct wlr_gbm_allocator *)alloc;
+}
+
+struct wlr_allocator *wlr_gbm_allocator_create(int drm_fd) {
+	int fd = fcntl(drm_fd, F_DUPFD_CLOEXEC, 0);
+	if (fd < 0) {
+		wlr_log(WLR_ERROR, "fcntl(F_DUPFD_CLOEXEC) failed");
+		return NULL;
+	}
+
+	uint64_t cap;
+	if (drmGetCap(fd, DRM_CAP_PRIME, &cap) ||
+			!(cap & DRM_PRIME_CAP_EXPORT)) {
+		wlr_log(WLR_ERROR, "PRIME export not supported");
+		return NULL;
+	}
+
+	struct wlr_gbm_allocator *alloc = calloc(1, sizeof(*alloc));
+	if (alloc == NULL) {
+		return NULL;
+	}
+	wlr_allocator_init(&alloc->base, &allocator_impl, WLR_BUFFER_CAP_DMABUF);
+
+	alloc->fd = fd;
+	wl_list_init(&alloc->buffers);
+
+	alloc->gbm_device = gbm_create_device(fd);
+	if (alloc->gbm_device == NULL) {
+		wlr_log(WLR_ERROR, "gbm_create_device failed");
+		free(alloc);
+		return NULL;
+	}
+
+	wlr_log(WLR_DEBUG, "Created GBM allocator with backend %s",
+		gbm_device_get_backend_name(alloc->gbm_device));
+	char *drm_name = drmGetDeviceNameFromFd2(fd);
+	wlr_log(WLR_DEBUG, "Using DRM node %s", drm_name);
+	free(drm_name);
+
+	return &alloc->base;
+}
+
+static void allocator_destroy(struct wlr_allocator *wlr_alloc) {
+	struct wlr_gbm_allocator *alloc = get_gbm_alloc_from_alloc(wlr_alloc);
+
+	// The gbm_bo objects need to be destroyed before the gbm_device
+	struct wlr_gbm_buffer *buf, *buf_tmp;
+	wl_list_for_each_safe(buf, buf_tmp, &alloc->buffers, link) {
+		gbm_bo_destroy(buf->gbm_bo);
+		buf->gbm_bo = NULL;
+		wl_list_remove(&buf->link);
+		wl_list_init(&buf->link);
+	}
+
+	gbm_device_destroy(alloc->gbm_device);
+	close(alloc->fd);
+	free(alloc);
+}
+
+static struct wlr_buffer *allocator_create_buffer(
+		struct wlr_allocator *wlr_alloc, int width, int height,
+		const struct wlr_drm_format *format) {
+	struct wlr_gbm_allocator *alloc = get_gbm_alloc_from_alloc(wlr_alloc);
+	struct wlr_gbm_buffer *buffer = create_buffer(alloc, width, height, format);
+	if (buffer == NULL) {
+		return NULL;
+	}
+	return &buffer->base;
+}
+
+static const struct wlr_allocator_interface allocator_impl = {
+	.destroy = allocator_destroy,
+	.create_buffer = allocator_create_buffer,
+};