[RFC 4/21] DRM: Add VIA DRM driver

[James Simmons <jsimmons@infradead.org>]

commit 6e79030fb92d3461b4a962630245d93944d5d349
Author: James Simmons <jsimmons@infradead.org>
Date:   Fri Jun 7 20:17:06 2013 -0400

    via: ttm pcie dma bo_driver handling
    
    Newer VIA hardware has moved from AGP to more modern PCIe
    based hardware. The TTM layer provides support for AGP but
    drm drivers need to handle PCIe support themselves. The
    code in via_sgdma.c provides the TTM backend so one can
    allows the graphics card direct access to the host system
    memory.
    
    Signed-Off-by: James Simmons <jsimmons@infradead.org>

diff --git a/drivers/gpu/drm/via/via_sgdma.c b/drivers/gpu/drm/via/via_sgdma.c
new file mode 100644
index 0000000..0dfd1a6
--- /dev/null
+++ b/drivers/gpu/drm/via/via_sgdma.c
@@ -0,0 +1,118 @@
+/**************************************************************************
+ *
+ * Copyright (c) 2012 James Simmons <jsimmons@infradead.org>
+ * All Rights Reserved.
+ *
+ * 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, sub license, 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 NON-INFRINGEMENT. IN NO EVENT SHALL
+ * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS 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.
+ */
+#include "via_drv.h"
+
+static int
+via_pcie_sgdma_bind(struct ttm_tt *ttm, struct ttm_mem_reg *mem)
+{
+	struct sgdma_tt *dma_tt = (struct sgdma_tt *) ttm;
+	struct ttm_bo_device *bdev = dma_tt->sgdma.ttm.bdev;
+	struct drm_via_private *dev_priv =
+		container_of(bdev, struct drm_via_private, bdev);
+	int i;
+
+	/* Disable gart table HW protect */
+	svga_wseq_mask(VGABASE, 0x6C, 0x00, BIT(7));
+
+	/* Update the relevant entries */
+	dma_tt->offset = mem->start << PAGE_SHIFT;
+	for (i = 0; i < ttm->num_pages; i++) {
+		writel(page_to_pfn(ttm->pages[i]) & 0x3FFFFFFF,
+			dev_priv->gart.virtual + dma_tt->offset + i);
+	}
+
+	/* Invalided GTI cache */
+	svga_wseq_mask(VGABASE, 0x6F, BIT(7), BIT(7));
+
+	/* Enable gart table HW protect */
+	svga_wseq_mask(VGABASE, 0x6C, BIT(7), BIT(7));
+	return 1;
+}
+
+static int
+via_pcie_sgdma_unbind(struct ttm_tt *ttm)
+{
+	struct sgdma_tt *dma_tt = (struct sgdma_tt *) ttm;
+	struct ttm_bo_device *bdev = dma_tt->sgdma.ttm.bdev;
+	struct drm_via_private *dev_priv =
+		container_of(bdev, struct drm_via_private, bdev);
+	int i;
+
+	if (ttm->state != tt_bound)
+		return 0;
+
+	/* Disable gart table HW protect */
+	svga_wseq_mask(VGABASE, 0x6C, 0x00, BIT(7));
+
+	/* Update the relevant entries */
+	for (i = 0; i < ttm->num_pages; i++)
+		writel(0x80000000, dev_priv->gart.virtual + dma_tt->offset + i);
+	dma_tt->offset = 0;
+
+	/* Invalided GTI cache */
+	svga_wseq_mask(VGABASE, 0x6F, BIT(7), BIT(7));
+
+	/* Enable gart table HW protect */
+	svga_wseq_mask(VGABASE, 0x6C, BIT(7), BIT(7));
+	return 0;
+}
+
+static void
+via_sgdma_destroy(struct ttm_tt *ttm)
+{
+	struct sgdma_tt *dma_tt = (struct sgdma_tt *) ttm;
+
+	if (ttm) {
+		ttm_dma_tt_fini(&dma_tt->sgdma);
+		kfree(dma_tt);
+	}
+}
+
+static struct ttm_backend_func ttm_sgdma_func = {
+	.bind = via_pcie_sgdma_bind,
+	.unbind = via_pcie_sgdma_unbind,
+	.destroy = via_sgdma_destroy,
+};
+
+struct ttm_tt *
+via_sgdma_backend_init(struct ttm_bo_device *bdev, unsigned long size,
+			uint32_t page_flags, struct page *dummy_read_page)
+{
+	struct sgdma_tt *dma_tt;
+
+	dma_tt = kzalloc(sizeof(*dma_tt), GFP_KERNEL);
+	if (!dma_tt)
+		return NULL;
+
+	dma_tt->sgdma.ttm.func = &ttm_sgdma_func;
+
+	if (ttm_dma_tt_init(&dma_tt->sgdma, bdev, size, page_flags, dummy_read_page)) {
+		kfree(dma_tt);
+		return NULL;
+	}
+	return &dma_tt->sgdma.ttm;
+}
+EXPORT_SYMBOL(via_sgdma_backend_init);