summaryrefslogtreecommitdiffstats
path: root/kernel/dma/coherent.c
blob: 5b5b6c7ec7f28e1f1a4b27f4eb25c1322230c458 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
// SPDX-License-Identifier: GPL-2.0
/*
 * Coherent per-device memory handling.
 * Borrowed from i386
 */
#include <linux/io.h>
#include <linux/slab.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/dma-direct.h>
#include <linux/dma-map-ops.h>

struct dma_coherent_mem {
	void		*virt_base;
	dma_addr_t	device_base;
	unsigned long	pfn_base;
	int		size;
	unsigned long	*bitmap;
	spinlock_t	spinlock;
	bool		use_dev_dma_pfn_offset;
};

static struct dma_coherent_mem *dma_coherent_default_memory __ro_after_init;

static inline struct dma_coherent_mem *dev_get_coherent_memory(struct device *dev)
{
	if (dev && dev->dma_mem)
		return dev->dma_mem;
	return NULL;
}

static inline dma_addr_t dma_get_device_base(struct device *dev,
					     struct dma_coherent_mem * mem)
{
	if (mem->use_dev_dma_pfn_offset)
		return phys_to_dma(dev, PFN_PHYS(mem->pfn_base));
	return mem->device_base;
}

static int dma_init_coherent_memory(phys_addr_t phys_addr,
		dma_addr_t device_addr, size_t size,
		struct dma_coherent_mem **mem)
{
	struct dma_coherent_mem *dma_mem = NULL;
	void *mem_base = NULL;
	int pages = size >> PAGE_SHIFT;
	int bitmap_size = BITS_TO_LONGS(pages) * sizeof(long);
	int ret;

	if (!size) {
		ret = -EINVAL;
		goto out;
	}

	mem_base = memremap(phys_addr, size, MEMREMAP_WC);
	if (!mem_base) {
		ret = -EINVAL;
		goto out;
	}
	dma_mem = kzalloc(sizeof(struct dma_coherent_mem), GFP_KERNEL);
	if (!dma_mem) {
		ret = -ENOMEM;
		goto out;
	}
	dma_mem->bitmap = kzalloc(bitmap_size, GFP_KERNEL);
	if (!dma_mem->bitmap) {
		ret = -ENOMEM;
		goto out;
	}

	dma_mem->virt_base = mem_base;
	dma_mem->device_base = device_addr;
	dma_mem->pfn_base = PFN_DOWN(phys_addr);
	dma_mem->size = pages;
	spin_lock_init(&dma_mem->spinlock);

	*mem = dma_mem;
	return 0;

out:
	kfree(dma_mem);
	if (mem_base)
		memunmap(mem_base);
	return ret;
}

static void dma_release_coherent_memory(struct dma_coherent_mem *mem)
{
	if (!mem)
		return;

	memunmap(mem->virt_base);
	kfree(mem->bitmap);
	kfree(mem);
}

static int dma_assign_coherent_memory(struct device *dev,
				      struct dma_coherent_mem *mem)
{
	if (!dev)
		return -ENODEV;

	if (dev->dma_mem)
		return -EBUSY;

	dev->dma_mem = mem;
	return 0;
}

/*
 * Declare a region of memory to be handed out by dma_alloc_coherent() when it
 * is asked for coherent memory for this device.  This shall only be used
 * from platform code, usually based on the device tree description.
 * 
 * phys_addr is the CPU physical address to which the memory is currently
 * assigned (this will be ioremapped so the CPU can access the region).
 *
 * device_addr is the DMA address the device needs to be programmed with to
 * actually address this memory (this will be handed out as the dma_addr_t in
 * dma_alloc_coherent()).
 *
 * size is the size of the area (must be a multiple of PAGE_SIZE).
 *
 * As a simplification for the platforms, only *one* such region of memory may
 * be declared per device.
 */
int dma_declare_coherent_memory(struct device *dev, phys_addr_t phys_addr,
				dma_addr_t device_addr, size_t size)
{
	struct dma_coherent_mem *mem;
	int ret;

	ret = dma_init_coherent_memory(phys_addr, device_addr, size, &mem);
	if (ret)
		return ret;

	ret = dma_assign_coherent_memory(dev, mem);
	if (ret)
		dma_release_coherent_memory(mem);
	return ret;
}

static void *__dma_alloc_from_coherent(struct device *dev,
				       struct dma_coherent_mem *mem,
				       ssize_t size, dma_addr_t *dma_handle)
{
	int order = get_order(size);
	unsigned long flags;
	int pageno;
	void *ret;

	spin_lock_irqsave(&mem->spinlock, flags);

	if (unlikely(size > ((dma_addr_t)mem->size << PAGE_SHIFT)))
		goto err;

	pageno = bitmap_find_free_region(mem->bitmap, mem->size, order);
	if (unlikely(pageno < 0))
		goto err;

	/*
	 * Memory was found in the coherent area.
	 */
	*dma_handle = dma_get_device_base(dev, mem) +
			((dma_addr_t)pageno << PAGE_SHIFT);
	ret = mem->virt_base + ((dma_addr_t)pageno << PAGE_SHIFT);
	spin_unlock_irqrestore(&mem->spinlock, flags);
	memset(ret, 0, size);
	return ret;
err:
	spin_unlock_irqrestore(&mem->spinlock, flags);
	return NULL;
}

/**
 * dma_alloc_from_dev_coherent() - allocate memory from device coherent pool
 * @dev:	device from which we allocate memory
 * @size:	size of requested memory area
 * @dma_handle:	This will be filled with the correct dma handle
 * @ret:	This pointer will be filled with the virtual address
 *		to allocated area.
 *
 * This function should be only called from per-arch dma_alloc_coherent()
 * to support allocation from per-device coherent memory pools.
 *
 * Returns 0 if dma_alloc_coherent should continue with allocating from
 * generic memory areas, or !0 if dma_alloc_coherent should return @ret.
 */
int dma_alloc_from_dev_coherent(struct device *dev, ssize_t size,
		dma_addr_t *dma_handle, void **ret)
{
	struct dma_coherent_mem *mem = dev_get_coherent_memory(dev);

	if (!mem)
		return 0;

	*ret = __dma_alloc_from_coherent(dev, mem, size, dma_handle);
	return 1;
}

void *dma_alloc_from_global_coherent(struct device *dev, ssize_t size,
				     dma_addr_t *dma_handle)
{
	if (!dma_coherent_default_memory)
		return NULL;

	return __dma_alloc_from_coherent(dev, dma_coherent_default_memory, size,
					 dma_handle);
}

static int __dma_release_from_coherent(struct dma_coherent_mem *mem,
				       int order, void *vaddr)
{
	if (mem && vaddr >= mem->virt_base && vaddr <
		   (mem->virt_base + ((dma_addr_t)mem->size << PAGE_SHIFT))) {
		int page = (vaddr - mem->virt_base) >> PAGE_SHIFT;
		unsigned long flags;

		spin_lock_irqsave(&mem->spinlock, flags);
		bitmap_release_region(mem->bitmap, page, order);
		spin_unlock_irqrestore(&mem->spinlock, flags);
		return 1;
	}
	return 0;
}

/**
 * dma_release_from_dev_coherent() - free memory to device coherent memory pool
 * @dev:	device from which the memory was allocated
 * @order:	the order of pages allocated
 * @vaddr:	virtual address of allocated pages
 *
 * This checks whether the memory was allocated from the per-device
 * coherent memory pool and if so, releases that memory.
 *
 * Returns 1 if we correctly released the memory, or 0 if the caller should
 * proceed with releasing memory from generic pools.
 */
int dma_release_from_dev_coherent(struct device *dev, int order, void *vaddr)
{
	struct dma_coherent_mem *mem = dev_get_coherent_memory(dev);

	return __dma_release_from_coherent(mem, order, vaddr);
}

int dma_release_from_global_coherent(int order, void *vaddr)
{
	if (!dma_coherent_default_memory)
		return 0;

	return __dma_release_from_coherent(dma_coherent_default_memory, order,
			vaddr);
}

static int __dma_mmap_from_coherent(struct dma_coherent_mem *mem,
		struct vm_area_struct *vma, void *vaddr, size_t size, int *ret)
{
	if (mem && vaddr >= mem->virt_base && vaddr + size <=
		   (mem->virt_base + ((dma_addr_t)mem->size << PAGE_SHIFT))) {
		unsigned long off = vma->vm_pgoff;
		int start = (vaddr - mem->virt_base) >> PAGE_SHIFT;
		unsigned long user_count = vma_pages(vma);
		int count = PAGE_ALIGN(size) >> PAGE_SHIFT;

		*ret = -ENXIO;
		if (off < count && user_count <= count - off) {
			unsigned long pfn = mem->pfn_base + start + off;
			*ret = remap_pfn_range(vma, vma->vm_start, pfn,
					       user_count << PAGE_SHIFT,
					       vma->vm_page_prot);
		}
		return 1;
	}
	return 0;
}

/**
 * dma_mmap_from_dev_coherent() - mmap memory from the device coherent pool
 * @dev:	device from which the memory was allocated
 * @vma:	vm_area for the userspace memory
 * @vaddr:	cpu address returned by dma_alloc_from_dev_coherent
 * @size:	size of the memory buffer allocated
 * @ret:	result from remap_pfn_range()
 *
 * This checks whether the memory was allocated from the per-device
 * coherent memory pool and if so, maps that memory to the provided vma.
 *
 * Returns 1 if @vaddr belongs to the device coherent pool and the caller
 * should return @ret, or 0 if they should proceed with mapping memory from
 * generic areas.
 */
int dma_mmap_from_dev_coherent(struct device *dev, struct vm_area_struct *vma,
			   void *vaddr, size_t size, int *ret)
{
	struct dma_coherent_mem *mem = dev_get_coherent_memory(dev);

	return __dma_mmap_from_coherent(mem, vma, vaddr, size, ret);
}

int dma_mmap_from_global_coherent(struct vm_area_struct *vma, void *vaddr,
				   size_t size, int *ret)
{
	if (!dma_coherent_default_memory)
		return 0;

	return __dma_mmap_from_coherent(dma_coherent_default_memory, vma,
					vaddr, size, ret);
}

/*
 * Support for reserved memory regions defined in device tree
 */
#ifdef CONFIG_OF_RESERVED_MEM
#include <linux/of.h>
#include <linux/of_fdt.h>
#include <linux/of_reserved_mem.h>

static struct reserved_mem *dma_reserved_default_memory __initdata;

static int rmem_dma_device_init(struct reserved_mem *rmem, struct device *dev)
{
	struct dma_coherent_mem *mem = rmem->priv;
	int ret;

	if (!mem) {
		ret = dma_init_coherent_memory(rmem->base, rmem->base,
					       rmem->size, &mem);
		if (ret) {
			pr_err("Reserved memory: failed to init DMA memory pool at %pa, size %ld MiB\n",
				&rmem->base, (unsigned long)rmem->size / SZ_1M);
			return ret;
		}
	}
	mem->use_dev_dma_pfn_offset = true;
	rmem->priv = mem;
	dma_assign_coherent_memory(dev, mem);
	return 0;
}

static void rmem_dma_device_release(struct reserved_mem *rmem,
				    struct device *dev)
{
	if (dev)
		dev->dma_mem = NULL;
}

static const struct reserved_mem_ops rmem_dma_ops = {
	.device_init	= rmem_dma_device_init,
	.device_release	= rmem_dma_device_release,
};

static int __init rmem_dma_setup(struct reserved_mem *rmem)
{
	unsigned long node = rmem->fdt_node;

	if (of_get_flat_dt_prop(node, "reusable", NULL))
		return -EINVAL;

#ifdef CONFIG_ARM
	if (!of_get_flat_dt_prop(node, "no-map", NULL)) {
		pr_err("Reserved memory: regions without no-map are not yet supported\n");
		return -EINVAL;
	}

	if (of_get_flat_dt_prop(node, "linux,dma-default", NULL)) {
		WARN(dma_reserved_default_memory,
		     "Reserved memory: region for default DMA coherent area is redefined\n");
		dma_reserved_default_memory = rmem;
	}
#endif

	rmem->ops = &rmem_dma_ops;
	pr_info("Reserved memory: created DMA memory pool at %pa, size %ld MiB\n",
		&rmem->base, (unsigned long)rmem->size / SZ_1M);
	return 0;
}

static int __init dma_init_reserved_memory(void)
{
	const struct reserved_mem_ops *ops;
	int ret;

	if (!dma_reserved_default_memory)
		return -ENOMEM;

	ops = dma_reserved_default_memory->ops;

	/*
	 * We rely on rmem_dma_device_init() does not propagate error of
	 * dma_assign_coherent_memory() for "NULL" device.
	 */
	ret = ops->device_init(dma_reserved_default_memory, NULL);

	if (!ret) {
		dma_coherent_default_memory = dma_reserved_default_memory->priv;
		pr_info("DMA: default coherent area is set\n");
	}

	return ret;
}

core_initcall(dma_init_reserved_memory);

RESERVEDMEM_OF_DECLARE(dma, "shared-dma-pool", rmem_dma_setup);
#endif