new file mode 100644
@@ -0,0 +1,100 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2018 Intel Corporation
+
+#include <linux/device.h>
+
+#include "ipu3.h"
+#include "ipu3-css-pool.h"
+#include "ipu3-dmamap.h"
+
+int ipu3_css_dma_buffer_resize(struct imgu_device *imgu,
+ struct ipu3_css_map *map, size_t size)
+{
+ if (map->size < size && map->vaddr) {
+ dev_warn(&imgu->pci_dev->dev, "dma buf resized from %zu to %zu",
+ map->size, size);
+
+ ipu3_dmamap_free(imgu, map);
+ if (!ipu3_dmamap_alloc(imgu, map, size))
+ return -ENOMEM;
+ }
+
+ return 0;
+}
+
+void ipu3_css_pool_cleanup(struct imgu_device *imgu, struct ipu3_css_pool *pool)
+{
+ unsigned int i;
+
+ for (i = 0; i < IPU3_CSS_POOL_SIZE; i++)
+ ipu3_dmamap_free(imgu, &pool->entry[i].param);
+}
+
+int ipu3_css_pool_init(struct imgu_device *imgu, struct ipu3_css_pool *pool,
+ size_t size)
+{
+ unsigned int i;
+
+ for (i = 0; i < IPU3_CSS_POOL_SIZE; i++) {
+ pool->entry[i].valid = false;
+ if (size == 0) {
+ pool->entry[i].param.vaddr = NULL;
+ continue;
+ }
+
+ if (!ipu3_dmamap_alloc(imgu, &pool->entry[i].param, size))
+ goto fail;
+ }
+
+ pool->last = IPU3_CSS_POOL_SIZE;
+
+ return 0;
+
+fail:
+ ipu3_css_pool_cleanup(imgu, pool);
+ return -ENOMEM;
+}
+
+/*
+ * Allocate a new parameter via recycling the oldest entry in the pool.
+ */
+void ipu3_css_pool_get(struct ipu3_css_pool *pool)
+{
+ /* Get the oldest entry */
+ u32 n = (pool->last + 1) % IPU3_CSS_POOL_SIZE;
+
+ pool->entry[n].valid = true;
+ pool->last = n;
+}
+
+/*
+ * Undo, for all practical purposes, the effect of pool_get().
+ */
+void ipu3_css_pool_put(struct ipu3_css_pool *pool)
+{
+ pool->entry[pool->last].valid = false;
+ pool->last = (pool->last + IPU3_CSS_POOL_SIZE - 1) % IPU3_CSS_POOL_SIZE;
+}
+
+/**
+ * ipu3_css_pool_last - Retrieve the nth pool entry from last
+ *
+ * @pool: a pointer to &struct ipu3_css_pool.
+ * @n: the distance to the last index.
+ *
+ * Returns:
+ * The nth entry from last or null map to indicate no frame stored.
+ */
+const struct ipu3_css_map *
+ipu3_css_pool_last(struct ipu3_css_pool *pool, unsigned int n)
+{
+ static const struct ipu3_css_map null_map = { 0 };
+ int i = (pool->last + IPU3_CSS_POOL_SIZE - n) % IPU3_CSS_POOL_SIZE;
+
+ WARN_ON(n >= IPU3_CSS_POOL_SIZE);
+
+ if (!pool->entry[i].valid)
+ return &null_map;
+
+ return &pool->entry[i].param;
+}
new file mode 100644
@@ -0,0 +1,55 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (C) 2018 Intel Corporation */
+
+#ifndef __IPU3_UTIL_H
+#define __IPU3_UTIL_H
+
+struct device;
+struct imgu_device;
+
+#define IPU3_CSS_POOL_SIZE 4
+
+/**
+ * ipu3_css_map - store DMA mapping info for buffer
+ *
+ * @size: size of the buffer in bytes.
+ * @vaddr: kernel virtual address.
+ * @daddr: iova dma address to access IPU3.
+ * @vma: private, a pointer to &struct vm_struct,
+ * used for ipu3_dmamap_free.
+ */
+struct ipu3_css_map {
+ size_t size;
+ void *vaddr;
+ dma_addr_t daddr;
+ struct vm_struct *vma;
+};
+
+/**
+ * ipu3_css_pool - circular buffer pool definition
+ *
+ * @entry: array with IPU3_CSS_POOL_SIZE elements.
+ * @entry.param: a &struct ipu3_css_map for storing the mem mapping.
+ * @entry.valid: used to mark if the entry has vaid data.
+ * @last: write pointer, initialized to IPU3_CSS_POOL_SIZE.
+ */
+struct ipu3_css_pool {
+ struct {
+ struct ipu3_css_map param;
+ bool valid;
+ } entry[IPU3_CSS_POOL_SIZE];
+ u32 last;
+};
+
+int ipu3_css_dma_buffer_resize(struct imgu_device *imgu,
+ struct ipu3_css_map *map, size_t size);
+void ipu3_css_pool_cleanup(struct imgu_device *imgu,
+ struct ipu3_css_pool *pool);
+int ipu3_css_pool_init(struct imgu_device *imgu, struct ipu3_css_pool *pool,
+ size_t size);
+void ipu3_css_pool_get(struct ipu3_css_pool *pool);
+void ipu3_css_pool_put(struct ipu3_css_pool *pool);
+const struct ipu3_css_map *ipu3_css_pool_last(struct ipu3_css_pool *pool,
+ u32 last);
+
+#endif