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/*
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 * Copyright © 2014 Intel Corporation
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 *
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 * Permission is hereby granted, free of charge, to any person obtaining a
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 * copy of this software and associated documentation files (the "Software"),
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 * to deal in the Software without restriction, including without limitation
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 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
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 * and/or sell copies of the Software, and to permit persons to whom the
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 * Software is furnished to do so, subject to the following conditions:
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 *
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 * The above copyright notice and this permission notice (including the next
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 * paragraph) shall be included in all copies or substantial portions of the
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 * Software.
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 *
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 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
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 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
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 * IN THE SOFTWARE.
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 *
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 */
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#include "i915_drv.h"
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#include "i915_gem_batch_pool.h"
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/**
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 * DOC: batch pool
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 *
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 * In order to submit batch buffers as 'secure', the software command parser
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 * must ensure that a batch buffer cannot be modified after parsing. It does
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 * this by copying the user provided batch buffer contents to a kernel owned
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 * buffer from which the hardware will actually execute, and by carefully
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 * managing the address space bindings for such buffers.
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 *
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 * The batch pool framework provides a mechanism for the driver to manage a
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 * set of scratch buffers to use for this purpose. The framework can be
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 * extended to support other uses cases should they arise.
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 */
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/**
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 * i915_gem_batch_pool_init() - initialize a batch buffer pool
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 * @dev: the drm device
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 * @pool: the batch buffer pool
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 */
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void i915_gem_batch_pool_init(struct drm_device *dev,
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			      struct i915_gem_batch_pool *pool)
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{
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	int n;
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	pool->dev = dev;
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	for (n = 0; n < ARRAY_SIZE(pool->cache_list); n++)
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		INIT_LIST_HEAD(&pool->cache_list[n]);
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}
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/**
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 * i915_gem_batch_pool_fini() - clean up a batch buffer pool
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 * @pool: the pool to clean up
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 *
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 * Note: Callers must hold the struct_mutex.
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 */
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void i915_gem_batch_pool_fini(struct i915_gem_batch_pool *pool)
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{
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	int n;
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	WARN_ON(!mutex_is_locked(&pool->dev->struct_mutex));
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	for (n = 0; n < ARRAY_SIZE(pool->cache_list); n++) {
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		while (!list_empty(&pool->cache_list[n])) {
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			struct drm_i915_gem_object *obj =
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				list_first_entry(&pool->cache_list[n],
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						 struct drm_i915_gem_object,
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						 batch_pool_link);
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			list_del(&obj->batch_pool_link);
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			drm_gem_object_unreference(&obj->base);
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		}
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	}
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}
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/**
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 * i915_gem_batch_pool_get() - allocate a buffer from the pool
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 * @pool: the batch buffer pool
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 * @size: the minimum desired size of the returned buffer
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 *
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 * Returns an inactive buffer from @pool with at least @size bytes,
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 * with the pages pinned. The caller must i915_gem_object_unpin_pages()
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 * on the returned object.
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 *
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 * Note: Callers must hold the struct_mutex
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 *
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 * Return: the buffer object or an error pointer
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 */
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struct drm_i915_gem_object *
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i915_gem_batch_pool_get(struct i915_gem_batch_pool *pool,
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			size_t size)
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{
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	struct drm_i915_gem_object *obj = NULL;
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	struct drm_i915_gem_object *tmp, *next;
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	struct list_head *list;
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	int n;
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	WARN_ON(!mutex_is_locked(&pool->dev->struct_mutex));
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	/* Compute a power-of-two bucket, but throw everything greater than
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	 * 16KiB into the same bucket: i.e. the the buckets hold objects of
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	 * (1 page, 2 pages, 4 pages, 8+ pages).
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	 */
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	n = fls(size >> PAGE_SHIFT) - 1;
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	if (n >= ARRAY_SIZE(pool->cache_list))
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		n = ARRAY_SIZE(pool->cache_list) - 1;
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	list = &pool->cache_list[n];
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	list_for_each_entry_safe(tmp, next, list, batch_pool_link) {
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		/* The batches are strictly LRU ordered */
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		if (tmp->active)
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			break;
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		/* While we're looping, do some clean up */
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		if (tmp->madv == __I915_MADV_PURGED) {
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			list_del(&tmp->batch_pool_link);
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			drm_gem_object_unreference(&tmp->base);
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			continue;
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		}
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		if (tmp->base.size >= size) {
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			obj = tmp;
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			break;
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		}
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	}
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	if (obj == NULL) {
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		int ret;
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		obj = i915_gem_alloc_object(pool->dev, size);
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		if (obj == NULL)
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			return ERR_PTR(-ENOMEM);
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		ret = i915_gem_object_get_pages(obj);
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		if (ret)
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			return ERR_PTR(ret);
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		obj->madv = I915_MADV_DONTNEED;
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	}
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	list_move_tail(&obj->batch_pool_link, list);
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	i915_gem_object_pin_pages(obj);
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	return obj;
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}