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}
138
139static void *__dma_alloc_from_coherent(struct device *dev,
140				       struct dma_coherent_mem *mem,
141				       ssize_t size, dma_addr_t *dma_handle)
142{
143	int order = get_order(size);
144	unsigned long flags;
145	int pageno;
146	void *ret;
147
148	spin_lock_irqsave(&mem->spinlock, flags);
149
150	if (unlikely(size > ((dma_addr_t)mem->size << PAGE_SHIFT)))
151		goto err;
152
153	pageno = bitmap_find_free_region(mem->bitmap, mem->size, order);
154	if (unlikely(pageno < 0))
155		goto err;
156
157	/*
158	 * Memory was found in the coherent area.
159	 */
160	*dma_handle = dma_get_device_base(dev, mem) +
161			((dma_addr_t)pageno << PAGE_SHIFT);
162	ret = mem->virt_base + ((dma_addr_t)pageno << PAGE_SHIFT);
163	spin_unlock_irqrestore(&mem->spinlock, flags);
164	memset(ret, 0, size);
165	return ret;
166err:
167	spin_unlock_irqrestore(&mem->spinlock, flags);
168	return NULL;
169}
170
171/**
172 * dma_alloc_from_dev_coherent() - allocate memory from device coherent pool
173 * @dev:	device from which we allocate memory
174 * @size:	size of requested memory area
175 * @dma_handle:	This will be filled with the correct dma handle
176 * @ret:	This pointer will be filled with the virtual address
177 *		to allocated area.
178 *
179 * This function should be only called from per-arch dma_alloc_coherent()
180 * to support allocation from per-device coherent memory pools.
181 *
182 * Returns 0 if dma_alloc_coherent should continue with allocating from
183 * generic memory areas, or !0 if dma_alloc_coherent should return @ret.
184 */
185int dma_alloc_from_dev_coherent(struct device *dev, ssize_t size,
186		dma_addr_t *dma_handle, void **ret)
187{
188	struct dma_coherent_mem *mem = dev_get_coherent_memory(dev);
189
190	if (!mem)
191		return 0;
192
193	*ret = __dma_alloc_from_coherent(dev, mem, size, dma_handle);
194	return 1;
195}
196
197static int __dma_release_from_coherent(struct dma_coherent_mem *mem,
198				       int order, void *vaddr)
199{
200	if (mem && vaddr >= mem->virt_base && vaddr <
201		   (mem->virt_base + ((dma_addr_t)mem->size << PAGE_SHIFT))) {
202		int page = (vaddr - mem->virt_base) >> PAGE_SHIFT;
203		unsigned long flags;
204
205		spin_lock_irqsave(&mem->spinlock, flags);
206		bitmap_release_region(mem->bitmap, page, order);
207		spin_unlock_irqrestore(&mem->spinlock, flags);
208		return 1;
209	}
210	return 0;
211}
212
213/**
214 * dma_release_from_dev_coherent() - free memory to device coherent memory pool
215 * @dev:	device from which the memory was allocated
216 * @order:	the order of pages allocated
217 * @vaddr:	virtual address of allocated pages
218 *
219 * This checks whether the memory was allocated from the per-device
220 * coherent memory pool and if so, releases that memory.
221 *
222 * Returns 1 if we correctly released the memory, or 0 if the caller should
223 * proceed with releasing memory from generic pools.
224 */
225int dma_release_from_dev_coherent(struct device *dev, int order, void *vaddr)
226{
227	struct dma_coherent_mem *mem = dev_get_coherent_memory(dev);
228
229	return __dma_release_from_coherent(mem, order, vaddr);
230}
231
232static int __dma_mmap_from_coherent(struct dma_coherent_mem *mem,
233		struct vm_area_struct *vma, void *vaddr, size_t size, int *ret)
234{
235	if (mem && vaddr >= mem->virt_base && vaddr + size <=
236		   (mem->virt_base + ((dma_addr_t)mem->size << PAGE_SHIFT))) {
237		unsigned long off = vma->vm_pgoff;
238		int start = (vaddr - mem->virt_base) >> PAGE_SHIFT;
239		unsigned long user_count = vma_pages(vma);
240		int count = PAGE_ALIGN(size) >> PAGE_SHIFT;
241
242		*ret = -ENXIO;
243		if (off < count && user_count <= count - off) {
244			unsigned long pfn = mem->pfn_base + start + off;
245			*ret = remap_pfn_range(vma, vma->vm_start, pfn,
246					       user_count << PAGE_SHIFT,
247					       vma->vm_page_prot);
248		}
249		return 1;
250	}
251	return 0;
252}
253
254/**
255 * dma_mmap_from_dev_coherent() - mmap memory from the device coherent pool
256 * @dev:	device from which the memory was allocated
257 * @vma:	vm_area for the userspace memory
258 * @vaddr:	cpu address returned by dma_alloc_from_dev_coherent
259 * @size:	size of the memory buffer allocated
260 * @ret:	result from remap_pfn_range()
261 *
262 * This checks whether the memory was allocated from the per-device
263 * coherent memory pool and if so, maps that memory to the provided vma.
264 *
265 * Returns 1 if @vaddr belongs to the device coherent pool and the caller
266 * should return @ret, or 0 if they should proceed with mapping memory from
267 * generic areas.
268 */
269int dma_mmap_from_dev_coherent(struct device *dev, struct vm_area_struct *vma,
270			   void *vaddr, size_t size, int *ret)
271{
272	struct dma_coherent_mem *mem = dev_get_coherent_memory(dev);
273
274	return __dma_mmap_from_coherent(mem, vma, vaddr, size, ret);
275}
276
277#ifdef CONFIG_DMA_GLOBAL_POOL
278static struct dma_coherent_mem *dma_coherent_default_memory __ro_after_init;
279
280void *dma_alloc_from_global_coherent(struct device *dev, ssize_t size,
281				     dma_addr_t *dma_handle)
282{
283	if (!dma_coherent_default_memory)
284		return NULL;
285
286	return __dma_alloc_from_coherent(dev, dma_coherent_default_memory, size,
287					 dma_handle);
288}
289
290int dma_release_from_global_coherent(int order, void *vaddr)
291{
292	if (!dma_coherent_default_memory)
293		return 0;
294
295	return __dma_release_from_coherent(dma_coherent_default_memory, order,
296			vaddr);
297}
298
299int dma_mmap_from_global_coherent(struct vm_area_struct *vma, void *vaddr,
300				   size_t size, int *ret)
301{
302	if (!dma_coherent_default_memory)
303		return 0;
304
305	return __dma_mmap_from_coherent(dma_coherent_default_memory, vma,
306					vaddr, size, ret);
307}
308
309int dma_init_global_coherent(phys_addr_t phys_addr, size_t size)
310{
311	struct dma_coherent_mem *mem;
312
313	mem = dma_init_coherent_memory(phys_addr, phys_addr, size, true);
314	if (IS_ERR(mem))
315		return PTR_ERR(mem);
316	dma_coherent_default_memory = mem;
317	pr_info("DMA: default coherent area is set\n");
318	return 0;
319}
320#endif /* CONFIG_DMA_GLOBAL_POOL */
321
322/*
323 * Support for reserved memory regions defined in device tree
324 */
325#ifdef CONFIG_OF_RESERVED_MEM
326#include <linux/of.h>
327#include <linux/of_fdt.h>
328#include <linux/of_reserved_mem.h>
329
330#ifdef CONFIG_DMA_GLOBAL_POOL
331static struct reserved_mem *dma_reserved_default_memory __initdata;
332#endif
333
334static int rmem_dma_device_init(struct reserved_mem *rmem, struct device *dev)
335{
336	if (!rmem->priv) {
337		struct dma_coherent_mem *mem;
338
339		mem = dma_init_coherent_memory(rmem->base, rmem->base,
340					       rmem->size, true);
341		if (IS_ERR(mem))
342			return PTR_ERR(mem);
343		rmem->priv = mem;
344	}
345	dma_assign_coherent_memory(dev, rmem->priv);
346	return 0;
347}
348
349static void rmem_dma_device_release(struct reserved_mem *rmem,
350				    struct device *dev)
351{
352	if (dev)
353		dev->dma_mem = NULL;
354}
355
356static const struct reserved_mem_ops rmem_dma_ops = {
357	.device_init	= rmem_dma_device_init,
358	.device_release	= rmem_dma_device_release,
359};
360
361static int __init rmem_dma_setup(struct reserved_mem *rmem)
362{
363	unsigned long node = rmem->fdt_node;
364
365	if (of_get_flat_dt_prop(node, "reusable", NULL))
366		return -EINVAL;
367
368#ifdef CONFIG_ARM
369	if (!of_get_flat_dt_prop(node, "no-map", NULL)) {
370		pr_err("Reserved memory: regions without no-map are not yet supported\n");
371		return -EINVAL;
372	}
373#endif
374
375#ifdef CONFIG_DMA_GLOBAL_POOL
376	if (of_get_flat_dt_prop(node, "linux,dma-default", NULL)) {
377		WARN(dma_reserved_default_memory,
378		     "Reserved memory: region for default DMA coherent area is redefined\n");
379		dma_reserved_default_memory = rmem;
380	}
381#endif
382
383	rmem->ops = &rmem_dma_ops;
384	pr_info("Reserved memory: created DMA memory pool at %pa, size %ld MiB\n",
385		&rmem->base, (unsigned long)rmem->size / SZ_1M);
386	return 0;
387}
388
389#ifdef CONFIG_DMA_GLOBAL_POOL
390static int __init dma_init_reserved_memory(void)
391{
392	if (!dma_reserved_default_memory)
393		return -ENOMEM;
394	return dma_init_global_coherent(dma_reserved_default_memory->base,
395					dma_reserved_default_memory->size);
396}
397core_initcall(dma_init_reserved_memory);
398#endif /* CONFIG_DMA_GLOBAL_POOL */
399
400RESERVEDMEM_OF_DECLARE(dma, "shared-dma-pool", rmem_dma_setup);
401#endif