1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Coherent per-device memory handling.
4 * Borrowed from i386
5 */
6#include <linux/io.h>
7#include <linux/slab.h>
8#include <linux/kernel.h>
9#include <linux/module.h>
10#include <linux/dma-direct.h>
11#include <linux/dma-map-ops.h>
12
13struct dma_coherent_mem {
14	void		*virt_base;
15	dma_addr_t	device_base;
16	unsigned long	pfn_base;
17	int		size;
18	unsigned long	*bitmap;
19	spinlock_t	spinlock;
20	bool		use_dev_dma_pfn_offset;
21};
22
23static inline struct dma_coherent_mem *dev_get_coherent_memory(struct device *dev)
24{
25	if (dev && dev->dma_mem)
26		return dev->dma_mem;
27	return NULL;
28}
29
30static inline dma_addr_t dma_get_device_base(struct device *dev,
31					     struct dma_coherent_mem * mem)
32{
33	if (mem->use_dev_dma_pfn_offset)
34		return phys_to_dma(dev, PFN_PHYS(mem->pfn_base));
35	return mem->device_base;
36}
37
38static struct dma_coherent_mem *dma_init_coherent_memory(phys_addr_t phys_addr,
39		dma_addr_t device_addr, size_t size, bool use_dma_pfn_offset)
40{
41	struct dma_coherent_mem *dma_mem;
42	int pages = size >> PAGE_SHIFT;
43	void *mem_base;
44
45	if (!size)
46		return ERR_PTR(-EINVAL);
47
48	mem_base = memremap(phys_addr, size, MEMREMAP_WC);
49	if (!mem_base)
50		return ERR_PTR(-EINVAL);
51
52	dma_mem = kzalloc(sizeof(struct dma_coherent_mem), GFP_KERNEL);
53	if (!dma_mem)
54		goto out_unmap_membase;
55	dma_mem->bitmap = bitmap_zalloc(pages, GFP_KERNEL);
56	if (!dma_mem->bitmap)
57		goto out_free_dma_mem;
58
59	dma_mem->virt_base = mem_base;
60	dma_mem->device_base = device_addr;
61	dma_mem->pfn_base = PFN_DOWN(phys_addr);
62	dma_mem->size = pages;
63	dma_mem->use_dev_dma_pfn_offset = use_dma_pfn_offset;
64	spin_lock_init(&dma_mem->spinlock);
65
66	return dma_mem;
67
68out_free_dma_mem:
69	kfree(dma_mem);
70out_unmap_membase:
71	memunmap(mem_base);
72	pr_err("Reserved memory: failed to init DMA memory pool at %pa, size %zd MiB\n",
73		&phys_addr, size / SZ_1M);
74	return ERR_PTR(-ENOMEM);
75}
76
77static void _dma_release_coherent_memory(struct dma_coherent_mem *mem)
78{
79	if (!mem)
80		return;
81
82	memunmap(mem->virt_base);
83	bitmap_free(mem->bitmap);
84	kfree(mem);
85}
86
87static int dma_assign_coherent_memory(struct device *dev,
88				      struct dma_coherent_mem *mem)
89{
90	if (!dev)
91		return -ENODEV;
92
93	if (dev->dma_mem)
94		return -EBUSY;
95
96	dev->dma_mem = mem;
97	return 0;
98}
99
100/*
101 * Declare a region of memory to be handed out by dma_alloc_coherent() when it
102 * is asked for coherent memory for this device.  This shall only be used
103 * from platform code, usually based on the device tree description.
104 *
105 * phys_addr is the CPU physical address to which the memory is currently
106 * assigned (this will be ioremapped so the CPU can access the region).
107 *
108 * device_addr is the DMA address the device needs to be programmed with to
109 * actually address this memory (this will be handed out as the dma_addr_t in
110 * dma_alloc_coherent()).
111 *
112 * size is the size of the area (must be a multiple of PAGE_SIZE).
113 *
114 * As a simplification for the platforms, only *one* such region of memory may
115 * be declared per device.
116 */
117int dma_declare_coherent_memory(struct device *dev, phys_addr_t phys_addr,
118				dma_addr_t device_addr, size_t size)
119{
120	struct dma_coherent_mem *mem;
121	int ret;
122
123	mem = dma_init_coherent_memory(phys_addr, device_addr, size, false);
124	if (IS_ERR(mem))
125		return PTR_ERR(mem);
126
127	ret = dma_assign_coherent_memory(dev, mem);
128	if (ret)
129		_dma_release_coherent_memory(mem);
130	return ret;
131}
132
133void dma_release_coherent_memory(struct device *dev)
134{
135	if (dev) {
136		_dma_release_coherent_memory(dev->dma_mem);
137		dev->dma_mem = NULL;
138	}
139}
140
141static void *__dma_alloc_from_coherent(struct device *dev,
142				       struct dma_coherent_mem *mem,
143				       ssize_t size, dma_addr_t *dma_handle)
144{
145	int order = get_order(size);
146	unsigned long flags;
147	int pageno;
148	void *ret;
149
150	spin_lock_irqsave(&mem->spinlock, flags);
151
152	if (unlikely(size > ((dma_addr_t)mem->size << PAGE_SHIFT)))
153		goto err;
154
155	pageno = bitmap_find_free_region(mem->bitmap, mem->size, order);
156	if (unlikely(pageno < 0))
157		goto err;
158
159	/*
160	 * Memory was found in the coherent area.
161	 */
162	*dma_handle = dma_get_device_base(dev, mem) +
163			((dma_addr_t)pageno << PAGE_SHIFT);
164	ret = mem->virt_base + ((dma_addr_t)pageno << PAGE_SHIFT);
165	spin_unlock_irqrestore(&mem->spinlock, flags);
166	memset(ret, 0, size);
167	return ret;
168err:
169	spin_unlock_irqrestore(&mem->spinlock, flags);
170	return NULL;
171}
172
173/**
174 * dma_alloc_from_dev_coherent() - allocate memory from device coherent pool
175 * @dev:	device from which we allocate memory
176 * @size:	size of requested memory area
177 * @dma_handle:	This will be filled with the correct dma handle
178 * @ret:	This pointer will be filled with the virtual address
179 *		to allocated area.
180 *
181 * This function should be only called from per-arch dma_alloc_coherent()
182 * to support allocation from per-device coherent memory pools.
183 *
184 * Returns 0 if dma_alloc_coherent should continue with allocating from
185 * generic memory areas, or !0 if dma_alloc_coherent should return @ret.
186 */
187int dma_alloc_from_dev_coherent(struct device *dev, ssize_t size,
188		dma_addr_t *dma_handle, void **ret)
189{
190	struct dma_coherent_mem *mem = dev_get_coherent_memory(dev);
191
192	if (!mem)
193		return 0;
194
195	*ret = __dma_alloc_from_coherent(dev, mem, size, dma_handle);
196	return 1;
197}
198
199static int __dma_release_from_coherent(struct dma_coherent_mem *mem,
200				       int order, void *vaddr)
201{
202	if (mem && vaddr >= mem->virt_base && vaddr <
203		   (mem->virt_base + ((dma_addr_t)mem->size << PAGE_SHIFT))) {
204		int page = (vaddr - mem->virt_base) >> PAGE_SHIFT;
205		unsigned long flags;
206
207		spin_lock_irqsave(&mem->spinlock, flags);
208		bitmap_release_region(mem->bitmap, page, order);
209		spin_unlock_irqrestore(&mem->spinlock, flags);
210		return 1;
211	}
212	return 0;
213}
214
215/**
216 * dma_release_from_dev_coherent() - free memory to device coherent memory pool
217 * @dev:	device from which the memory was allocated
218 * @order:	the order of pages allocated
219 * @vaddr:	virtual address of allocated pages
220 *
221 * This checks whether the memory was allocated from the per-device
222 * coherent memory pool and if so, releases that memory.
223 *
224 * Returns 1 if we correctly released the memory, or 0 if the caller should
225 * proceed with releasing memory from generic pools.
226 */
227int dma_release_from_dev_coherent(struct device *dev, int order, void *vaddr)
228{
229	struct dma_coherent_mem *mem = dev_get_coherent_memory(dev);
230
231	return __dma_release_from_coherent(mem, order, vaddr);
232}
233
234static int __dma_mmap_from_coherent(struct dma_coherent_mem *mem,
235		struct vm_area_struct *vma, void *vaddr, size_t size, int *ret)
236{
237	if (mem && vaddr >= mem->virt_base && vaddr + size <=
238		   (mem->virt_base + ((dma_addr_t)mem->size << PAGE_SHIFT))) {
239		unsigned long off = vma->vm_pgoff;
240		int start = (vaddr - mem->virt_base) >> PAGE_SHIFT;
241		unsigned long user_count = vma_pages(vma);
242		int count = PAGE_ALIGN(size) >> PAGE_SHIFT;
243
244		*ret = -ENXIO;
245		if (off < count && user_count <= count - off) {
246			unsigned long pfn = mem->pfn_base + start + off;
247			*ret = remap_pfn_range(vma, vma->vm_start, pfn,
248					       user_count << PAGE_SHIFT,
249					       vma->vm_page_prot);
250		}
251		return 1;
252	}
253	return 0;
254}
255
256/**
257 * dma_mmap_from_dev_coherent() - mmap memory from the device coherent pool
258 * @dev:	device from which the memory was allocated
259 * @vma:	vm_area for the userspace memory
260 * @vaddr:	cpu address returned by dma_alloc_from_dev_coherent
261 * @size:	size of the memory buffer allocated
262 * @ret:	result from remap_pfn_range()
263 *
264 * This checks whether the memory was allocated from the per-device
265 * coherent memory pool and if so, maps that memory to the provided vma.
266 *
267 * Returns 1 if @vaddr belongs to the device coherent pool and the caller
268 * should return @ret, or 0 if they should proceed with mapping memory from
269 * generic areas.
270 */
271int dma_mmap_from_dev_coherent(struct device *dev, struct vm_area_struct *vma,
272			   void *vaddr, size_t size, int *ret)
273{
274	struct dma_coherent_mem *mem = dev_get_coherent_memory(dev);
275
276	return __dma_mmap_from_coherent(mem, vma, vaddr, size, ret);
277}
278
279#ifdef CONFIG_DMA_GLOBAL_POOL
280static struct dma_coherent_mem *dma_coherent_default_memory __ro_after_init;
281
282void *dma_alloc_from_global_coherent(struct device *dev, ssize_t size,
283				     dma_addr_t *dma_handle)
284{
285	if (!dma_coherent_default_memory)
286		return NULL;
287
288	return __dma_alloc_from_coherent(dev, dma_coherent_default_memory, size,
289					 dma_handle);
290}
291
292int dma_release_from_global_coherent(int order, void *vaddr)
293{
294	if (!dma_coherent_default_memory)
295		return 0;
296
297	return __dma_release_from_coherent(dma_coherent_default_memory, order,
298			vaddr);
299}
300
301int dma_mmap_from_global_coherent(struct vm_area_struct *vma, void *vaddr,
302				   size_t size, int *ret)
303{
304	if (!dma_coherent_default_memory)
305		return 0;
306
307	return __dma_mmap_from_coherent(dma_coherent_default_memory, vma,
308					vaddr, size, ret);
309}
310
311int dma_init_global_coherent(phys_addr_t phys_addr, size_t size)
312{
313	struct dma_coherent_mem *mem;
314
315	mem = dma_init_coherent_memory(phys_addr, phys_addr, size, true);
316	if (IS_ERR(mem))
317		return PTR_ERR(mem);
318	dma_coherent_default_memory = mem;
319	pr_info("DMA: default coherent area is set\n");
320	return 0;
321}
322#endif /* CONFIG_DMA_GLOBAL_POOL */
323
324/*
325 * Support for reserved memory regions defined in device tree
326 */
327#ifdef CONFIG_OF_RESERVED_MEM
328#include <linux/of.h>
329#include <linux/of_fdt.h>
330#include <linux/of_reserved_mem.h>
331
332#ifdef CONFIG_DMA_GLOBAL_POOL
333static struct reserved_mem *dma_reserved_default_memory __initdata;
334#endif
335
336static int rmem_dma_device_init(struct reserved_mem *rmem, struct device *dev)
337{
338	if (!rmem->priv) {
339		struct dma_coherent_mem *mem;
340
341		mem = dma_init_coherent_memory(rmem->base, rmem->base,
342					       rmem->size, true);
343		if (IS_ERR(mem))
344			return PTR_ERR(mem);
345		rmem->priv = mem;
346	}
347	dma_assign_coherent_memory(dev, rmem->priv);
348	return 0;
349}
350
351static void rmem_dma_device_release(struct reserved_mem *rmem,
352				    struct device *dev)
353{
354	if (dev)
355		dev->dma_mem = NULL;
356}
357
358static const struct reserved_mem_ops rmem_dma_ops = {
359	.device_init	= rmem_dma_device_init,
360	.device_release	= rmem_dma_device_release,
361};
362
363static int __init rmem_dma_setup(struct reserved_mem *rmem)
364{
365	unsigned long node = rmem->fdt_node;
366
367	if (of_get_flat_dt_prop(node, "reusable", NULL))
368		return -EINVAL;
369
370#ifdef CONFIG_ARM
371	if (!of_get_flat_dt_prop(node, "no-map", NULL)) {
372		pr_err("Reserved memory: regions without no-map are not yet supported\n");
373		return -EINVAL;
374	}
375#endif
376
377#ifdef CONFIG_DMA_GLOBAL_POOL
378	if (of_get_flat_dt_prop(node, "linux,dma-default", NULL)) {
379		WARN(dma_reserved_default_memory,
380		     "Reserved memory: region for default DMA coherent area is redefined\n");
381		dma_reserved_default_memory = rmem;
382	}
383#endif
384
385	rmem->ops = &rmem_dma_ops;
386	pr_info("Reserved memory: created DMA memory pool at %pa, size %ld MiB\n",
387		&rmem->base, (unsigned long)rmem->size / SZ_1M);
388	return 0;
389}
390
391#ifdef CONFIG_DMA_GLOBAL_POOL
392static int __init dma_init_reserved_memory(void)
393{
394	if (!dma_reserved_default_memory)
395		return -ENOMEM;
396	return dma_init_global_coherent(dma_reserved_default_memory->base,
397					dma_reserved_default_memory->size);
398}
399core_initcall(dma_init_reserved_memory);
400#endif /* CONFIG_DMA_GLOBAL_POOL */
401
402RESERVEDMEM_OF_DECLARE(dma, "shared-dma-pool", rmem_dma_setup);
403#endif
404