drm: base prime/dma-buf support (v5)

This adds the basic drm dma-buf interface layer, called PRIME. This
commit doesn't add any driver support, it is simply and agreed upon starting
point so we can work towards merging driver support for the next merge window.

Current drivers with work done are nouveau, i915, udl, exynos and omap.

The main APIs exposed to userspace allow translating a 32-bit object handle
to a file descriptor, and a file descriptor to a 32-bit object handle.

The flags value is currently limited to O_CLOEXEC.

Acknowledgements:
Daniel Vetter: lots of review
Rob Clark: cleaned up lots of the internals and did lifetime review.

v2: rename some functions after Chris preferred a green shed
fix IS_ERR_OR_NULL -> IS_ERR
v3: Fix Ville pointed out using buffer + kmalloc
v4: add locking as per ickle review
v5: allow re-exporting the original dma-buf (Daniel)

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Rob Clark <rob.clark@linaro.org>
Reviewed-by: Sumit Semwal <sumit.semwal@linaro.org>
Reviewed-by: Inki Dae <inki.dae@samsung.com>
Acked-by: Ben Widawsky <benjamin.widawsky@intel.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

2 files changed, 75 insertions, 1 deletions

diff --git a/include/drm/drm.h b/include/drm/drm.h
index 34a7b89fd006..64ff02d5b730 100644
--- a/include/drm/drm.h
+++ b/include/drm/drm.h
@@ -617,6 +617,17 @@ struct drm_get_cap {
         __u64 value;
 };
 
+#define DRM_CLOEXEC O_CLOEXEC
+struct drm_prime_handle {
+        __u32 handle;
+
+        /** Flags.. only applicable for handle->fd */
+        __u32 flags;
+
+        /** Returned dmabuf file descriptor */
+        __s32 fd;
+};
+
 #include "drm_mode.h"
 
 #define DRM_IOCTL_BASE                  'd'
@@ -673,7 +684,8 @@ struct drm_get_cap {
 #define DRM_IOCTL_UNLOCK                DRM_IOW( 0x2b, struct drm_lock)
 #define DRM_IOCTL_FINISH                DRM_IOW( 0x2c, struct drm_lock)
 
-#define DRM_IOCTL_GEM_PRIME_OPEN        DRM_IOWR(0x2e, struct drm_gem_open)
+#define DRM_IOCTL_PRIME_HANDLE_TO_FD    DRM_IOWR(0x2d, struct drm_prime_handle)
+#define DRM_IOCTL_PRIME_FD_TO_HANDLE    DRM_IOWR(0x2e, struct drm_prime_handle)
 
 #define DRM_IOCTL_AGP_ACQUIRE           DRM_IO(  0x30)
 #define DRM_IOCTL_AGP_RELEASE           DRM_IO(  0x31)
diff --git a/include/drm/drmP.h b/include/drm/drmP.h
index 574bd1c81ebd..dd731043fecd 100644
--- a/include/drm/drmP.h
+++ b/include/drm/drmP.h
@@ -91,6 +91,7 @@ struct drm_device;
 #define DRM_UT_CORE             0x01
 #define DRM_UT_DRIVER           0x02
 #define DRM_UT_KMS              0x04
+#define DRM_UT_PRIME            0x08
 /*
  * Three debug levels are defined.
  * drm_core, drm_driver, drm_kms
@@ -150,6 +151,7 @@ int drm_err(const char *func, const char *format, ...);
 #define DRIVER_IRQ_VBL2    0x800
 #define DRIVER_GEM         0x1000
 #define DRIVER_MODESET     0x2000
+#define DRIVER_PRIME       0x4000
 
 #define DRIVER_BUS_PCI 0x1
 #define DRIVER_BUS_PLATFORM 0x2
@@ -215,6 +217,11 @@ int drm_err(const char *func, const char *format, ...);
                 drm_ut_debug_printk(DRM_UT_KMS, DRM_NAME,               \
                                          __func__, fmt, ##args);        \
         } while (0)
+#define DRM_DEBUG_PRIME(fmt, args...)                                   \
+        do {                                                            \
+                drm_ut_debug_printk(DRM_UT_PRIME, DRM_NAME,             \
+                                        __func__, fmt, ##args);         \
+        } while (0)
 #define DRM_LOG(fmt, args...)                                           \
         do {                                                            \
                 drm_ut_debug_printk(DRM_UT_CORE, NULL,                  \
@@ -238,6 +245,7 @@ int drm_err(const char *func, const char *format, ...);
 #else
 #define DRM_DEBUG_DRIVER(fmt, args...) do { } while (0)
 #define DRM_DEBUG_KMS(fmt, args...)     do { } while (0)
+#define DRM_DEBUG_PRIME(fmt, args...)   do { } while (0)
 #define DRM_DEBUG(fmt, arg...)           do { } while (0)
 #define DRM_LOG(fmt, arg...)            do { } while (0)
 #define DRM_LOG_KMS(fmt, args...) do { } while (0)
@@ -410,6 +418,12 @@ struct drm_pending_event {
         void (*destroy)(struct drm_pending_event *event);
 };
 
+/* initial implementaton using a linked list - todo hashtab */
+struct drm_prime_file_private {
+        struct list_head head;
+        struct mutex lock;
+};
+
 /** File private data */
 struct drm_file {
         int authenticated;
@@ -437,6 +451,8 @@ struct drm_file {
         wait_queue_head_t event_wait;
         struct list_head event_list;
         int event_space;
+
+        struct drm_prime_file_private prime;
 };
 
 /** Wait queue */
@@ -652,6 +668,12 @@ struct drm_gem_object {
         uint32_t pending_write_domain;
 
         void *driver_private;
+
+        /* dma buf exported from this GEM object */
+        struct dma_buf *export_dma_buf;
+
+        /* dma buf attachment backing this object */
+        struct dma_buf_attachment *import_attach;
 };
 
 #include "drm_crtc.h"
@@ -890,6 +912,20 @@ struct drm_driver {
         int (*gem_open_object) (struct drm_gem_object *, struct drm_file *);
         void (*gem_close_object) (struct drm_gem_object *, struct drm_file *);
 
+        /* prime: */
+        /* export handle -> fd (see drm_gem_prime_handle_to_fd() helper) */
+        int (*prime_handle_to_fd)(struct drm_device *dev, struct drm_file *file_priv,
+                                uint32_t handle, uint32_t flags, int *prime_fd);
+        /* import fd -> handle (see drm_gem_prime_fd_to_handle() helper) */
+        int (*prime_fd_to_handle)(struct drm_device *dev, struct drm_file *file_priv,
+                                int prime_fd, uint32_t *handle);
+        /* export GEM -> dmabuf */
+        struct dma_buf * (*gem_prime_export)(struct drm_device *dev,
+                                struct drm_gem_object *obj, int flags);
+        /* import dmabuf -> GEM */
+        struct drm_gem_object * (*gem_prime_import)(struct drm_device *dev,
+                                struct dma_buf *dma_buf);
+
         /* vga arb irq handler */
         void (*vgaarb_irq)(struct drm_device *dev, bool state);
 
@@ -1509,6 +1545,32 @@ extern int drm_vblank_info(struct seq_file *m, void *data);
 extern int drm_clients_info(struct seq_file *m, void* data);
 extern int drm_gem_name_info(struct seq_file *m, void *data);
 
+
+extern int drm_gem_prime_handle_to_fd(struct drm_device *dev,
+                struct drm_file *file_priv, uint32_t handle, uint32_t flags,
+                int *prime_fd);
+extern int drm_gem_prime_fd_to_handle(struct drm_device *dev,
+                struct drm_file *file_priv, int prime_fd, uint32_t *handle);
+
+extern int drm_prime_handle_to_fd_ioctl(struct drm_device *dev, void *data,
+                                        struct drm_file *file_priv);
+extern int drm_prime_fd_to_handle_ioctl(struct drm_device *dev, void *data,
+                                        struct drm_file *file_priv);
+
+extern struct sg_table *drm_prime_pages_to_sg(struct page **pages, int nr_pages);
+extern void drm_prime_gem_destroy(struct drm_gem_object *obj, struct sg_table *sg);
+
+
+void drm_prime_init_file_private(struct drm_prime_file_private *prime_fpriv);
+void drm_prime_destroy_file_private(struct drm_prime_file_private *prime_fpriv);
+int drm_prime_add_imported_buf_handle(struct drm_prime_file_private *prime_fpriv, struct dma_buf *dma_buf, uint32_t handle);
+int drm_prime_lookup_imported_buf_handle(struct drm_prime_file_private *prime_fpriv, struct dma_buf *dma_buf, uint32_t *handle);
+void drm_prime_remove_imported_buf_handle(struct drm_prime_file_private *prime_fpriv, struct dma_buf *dma_buf);
+
+int drm_prime_add_dma_buf(struct drm_device *dev, struct drm_gem_object *obj);
+int drm_prime_lookup_obj(struct drm_device *dev, struct dma_buf *buf,
+                         struct drm_gem_object **obj);
+
 #if DRM_DEBUG_CODE
 extern int drm_vma_info(struct seq_file *m, void *data);
 #endif