media: staging/intel-ipu3: css: Add dma buff pool utility functions

The pools are used to store previous parameters set by
user with the parameter queue. Due to pipelining,
there needs to be multiple sets (up to four)
of parameters which are queued in a host-to-sp queue.

[mchehab@kernel.org: fixed two minor issues on comments: a space before
 tab and a typo: "vaid" -> "valid"]
Signed-off-by: Yong Zhi <yong.zhi@intel.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

drivers/staging/media/ipu3/ipu3-css-pool.c

+// 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;
+}

drivers/staging/media/ipu3/ipu3-css-pool.h

+/* 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 valid 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