video: adf: add memblock helper

Provides a dma-buf exporter for memblocks, mainly useful for ADF devices
to wrap their bootloader logos

Change-Id: I936a9b5df099ab6084d433fcaf50f3bc29f93289
Signed-off-by: Greg Hackmann <ghackmann@google.com>

drivers/video/adf/Kconfig

@@ -2,3 +2,8 @@ menuconfig ADF
 	depends on SYNC
 	depends on DMA_SHARED_BUFFER
 	tristate "Atomic Display Framework"
+
+menuconfig ADF_MEMBLOCK
+	depends on ADF
+	depends on HAVE_MEMBLOCK
+	tristate "Helper for using memblocks as buffers in ADF drivers"

drivers/video/adf/Makefile

@@ -9,3 +9,5 @@ obj-$(CONFIG_ADF) += adf.o \
 	adf_sysfs.o
 
 obj-$(CONFIG_COMPAT) += adf_fops32.o
+
+obj-$(CONFIG_ADF_MEMBLOCK) += adf_memblock.o

drivers/video/adf/adf_memblock.c

@@ -0,0 +1,149 @@
+/*
+ * Copyright (C) 2013 Google, Inc.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * 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.
+ *
+ */
+
+#include <linux/dma-buf.h>
+#include <linux/highmem.h>
+#include <linux/memblock.h>
+#include <linux/slab.h>
+
+struct adf_memblock_pdata {
+	phys_addr_t base;
+};
+
+static struct sg_table *adf_memblock_map(struct dma_buf_attachment *attach,
+		enum dma_data_direction direction)
+{
+	struct adf_memblock_pdata *pdata = attach->dmabuf->priv;
+	unsigned long pfn = PFN_DOWN(pdata->base);
+	struct page *page = pfn_to_page(pfn);
+	struct sg_table *table;
+	int ret;
+
+	table = kzalloc(sizeof(*table), GFP_KERNEL);
+	if (!table)
+		return ERR_PTR(-ENOMEM);
+
+	ret = sg_alloc_table(table, 1, GFP_KERNEL);
+	if (ret < 0)
+		goto err;
+
+	sg_set_page(table->sgl, page, attach->dmabuf->size, 0);
+	return table;
+
+err:
+	kfree(table);
+	return ERR_PTR(ret);
+}
+
+static void adf_memblock_unmap(struct dma_buf_attachment *attach,
+		struct sg_table *table, enum dma_data_direction direction)
+{
+	sg_free_table(table);
+}
+
+static void __init_memblock adf_memblock_release(struct dma_buf *buf)
+{
+	struct adf_memblock_pdata *pdata = buf->priv;
+	int err = memblock_free(pdata->base, buf->size);
+
+	if (err < 0)
+		pr_warn("%s: freeing memblock failed: %d\n", __func__, err);
+	kfree(pdata);
+}
+
+static void *adf_memblock_do_kmap(struct dma_buf *buf, unsigned long pgoffset,
+		bool atomic)
+{
+	struct adf_memblock_pdata *pdata = buf->priv;
+	unsigned long pfn = PFN_DOWN(pdata->base) + pgoffset;
+	struct page *page = pfn_to_page(pfn);
+
+	if (atomic)
+		return kmap_atomic(page);
+	else
+		return kmap(page);
+}
+
+static void *adf_memblock_kmap_atomic(struct dma_buf *buf,
+		unsigned long pgoffset)
+{
+	return adf_memblock_do_kmap(buf, pgoffset, true);
+}
+
+static void adf_memblock_kunmap_atomic(struct dma_buf *buf,
+		unsigned long pgoffset, void *vaddr)
+{
+	kunmap_atomic(vaddr);
+}
+
+static void *adf_memblock_kmap(struct dma_buf *buf, unsigned long pgoffset)
+{
+	return adf_memblock_do_kmap(buf, pgoffset, false);
+}
+
+static void adf_memblock_kunmap(struct dma_buf *buf, unsigned long pgoffset,
+		void *vaddr)
+{
+	kunmap(vaddr);
+}
+
+static int adf_memblock_mmap(struct dma_buf *buf, struct vm_area_struct *vma)
+{
+	struct adf_memblock_pdata *pdata = buf->priv;
+
+	return remap_pfn_range(vma, vma->vm_start, PFN_DOWN(pdata->base),
+			vma->vm_end - vma->vm_start, vma->vm_page_prot);
+}
+
+struct dma_buf_ops adf_memblock_ops = {
+	.map_dma_buf = adf_memblock_map,
+	.unmap_dma_buf = adf_memblock_unmap,
+	.release = adf_memblock_release,
+	.kmap_atomic = adf_memblock_kmap_atomic,
+	.kunmap_atomic = adf_memblock_kunmap_atomic,
+	.kmap = adf_memblock_kmap,
+	.kunmap = adf_memblock_kunmap,
+	.mmap = adf_memblock_mmap,
+};
+
+/**
+ * adf_memblock_export - export a memblock reserved area as a dma-buf
+ *
+ * @base: base physical address
+ * @size: memblock size
+ * @flags: mode flags for the dma-buf's file
+ *
+ * @base and @size must be page-aligned.
+ *
+ * Returns a dma-buf on success or ERR_PTR(-errno) on failure.
+ */
+struct dma_buf *adf_memblock_export(phys_addr_t base, size_t size, int flags)
+{
+	struct adf_memblock_pdata *pdata;
+	struct dma_buf *buf;
+
+	if (PAGE_ALIGN(base) != base || PAGE_ALIGN(size) != size)
+		return ERR_PTR(-EINVAL);
+
+	pdata = kzalloc(sizeof(*pdata), GFP_KERNEL);
+	if (!pdata)
+		return ERR_PTR(-ENOMEM);
+
+	pdata->base = base;
+	buf = dma_buf_export(pdata, &adf_memblock_ops, size, flags);
+	if (IS_ERR(buf))
+		kfree(pdata);
+
+	return buf;
+}

include/video/adf_memblock.h

@@ -0,0 +1,20 @@
+/*
+ * Copyright (C) 2013 Google, Inc.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * 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.
+ *
+ */
+
+#ifndef _VIDEO_ADF_MEMBLOCK_H_
+#define _VIDEO_ADF_MEMBLOCK_H_
+
+struct dma_buf *adf_memblock_export(phys_addr_t base, size_t size, int flags);
+
+#endif /* _VIDEO_ADF_MEMBLOCK_H_ */