staging: add omapdrm DRM/KMS driver for TI OMAP platforms

[pandora-kernel.git] / drivers / staging / omapdrm / omap_gem_helpers.c

diff --git a/drivers/staging/omapdrm/omap_gem_helpers.c b/drivers/staging/omapdrm/omap_gem_helpers.c
new file mode 100644 (file)
index 0000000..1cfc12d
--- /dev/null
+++ b/drivers/staging/omapdrm/omap_gem_helpers.c
@@ -0,0 +1,114 @@
+/*
+ * drivers/staging/omapdrm/omap_gem_helpers.c
+ *
+ * Copyright (C) 2011 Texas Instruments
+ * Author: Rob Clark <rob.clark@linaro.org>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/* temporary copy of drm_gem_{get,put}_pages() until the
+ * "drm/gem: add functions to get/put pages" patch is merged..
+ */
+
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/shmem_fs.h>
+
+#include <drm/drmP.h>
+
+/**
+ * drm_gem_get_pages - helper to allocate backing pages for a GEM object
+ * @obj: obj in question
+ * @gfpmask: gfp mask of requested pages
+ */
+struct page ** _drm_gem_get_pages(struct drm_gem_object *obj, gfp_t gfpmask)
+{
+       struct inode *inode;
+       struct address_space *mapping;
+       struct page *p, **pages;
+       int i, npages;
+
+       /* This is the shared memory object that backs the GEM resource */
+       inode = obj->filp->f_path.dentry->d_inode;
+       mapping = inode->i_mapping;
+
+       npages = obj->size >> PAGE_SHIFT;
+
+       pages = drm_malloc_ab(npages, sizeof(struct page *));
+       if (pages == NULL)
+               return ERR_PTR(-ENOMEM);
+
+       gfpmask |= mapping_gfp_mask(mapping);
+
+       for (i = 0; i < npages; i++) {
+               p = shmem_read_mapping_page_gfp(mapping, i, gfpmask);
+               if (IS_ERR(p))
+                       goto fail;
+               pages[i] = p;
+
+               /* There is a hypothetical issue w/ drivers that require
+                * buffer memory in the low 4GB.. if the pages are un-
+                * pinned, and swapped out, they can end up swapped back
+                * in above 4GB.  If pages are already in memory, then
+                * shmem_read_mapping_page_gfp will ignore the gfpmask,
+                * even if the already in-memory page disobeys the mask.
+                *
+                * It is only a theoretical issue today, because none of
+                * the devices with this limitation can be populated with
+                * enough memory to trigger the issue.  But this BUG_ON()
+                * is here as a reminder in case the problem with
+                * shmem_read_mapping_page_gfp() isn't solved by the time
+                * it does become a real issue.
+                *
+                * See this thread: http://lkml.org/lkml/2011/7/11/238
+                */
+               BUG_ON((gfpmask & __GFP_DMA32) &&
+                               (page_to_pfn(p) >= 0x00100000UL));
+       }
+
+       return pages;
+
+fail:
+       while (i--) {
+               page_cache_release(pages[i]);
+       }
+       drm_free_large(pages);
+       return ERR_PTR(PTR_ERR(p));
+}
+
+/**
+ * drm_gem_put_pages - helper to free backing pages for a GEM object
+ * @obj: obj in question
+ * @pages: pages to free
+ */
+void _drm_gem_put_pages(struct drm_gem_object *obj, struct page **pages,
+               bool dirty, bool accessed)
+{
+       int i, npages;
+
+       npages = obj->size >> PAGE_SHIFT;
+
+       for (i = 0; i < npages; i++) {
+               if (dirty)
+                       set_page_dirty(pages[i]);
+
+               if (accessed)
+                       mark_page_accessed(pages[i]);
+
+               /* Undo the reference we took when populating the table */
+               page_cache_release(pages[i]);
+       }
+
+       drm_free_large(pages);
+}