1/*
  2 * Contiguous Memory Allocator for DMA mapping framework
  3 * Copyright (c) 2010-2011 by Samsung Electronics.
  4 * Written by:
  5 *	Marek Szyprowski <m.szyprowski@samsung.com>
  6 *	Michal Nazarewicz <mina86@mina86.com>
  7 *
  8 * This program is free software; you can redistribute it and/or
  9 * modify it under the terms of the GNU General Public License as
 10 * published by the Free Software Foundation; either version 2 of the
 11 * License or (at your optional) any later version of the license.
 12 */
 13
 14#define pr_fmt(fmt) "cma: " fmt
 15
 16#ifdef CONFIG_CMA_DEBUG
 17#ifndef DEBUG
 18#  define DEBUG
 19#endif
 20#endif
 21
 22#include <asm/page.h>
 23#include <asm/dma-contiguous.h>
 24
 25#include <linux/memblock.h>
 26#include <linux/err.h>
 27#include <linux/mm.h>
 28#include <linux/mutex.h>
 29#include <linux/page-isolation.h>
 30#include <linux/sizes.h>
 31#include <linux/slab.h>
 32#include <linux/swap.h>
 33#include <linux/mm_types.h>
 34#include <linux/dma-contiguous.h>
 35
 36struct cma {
 37	unsigned long	base_pfn;
 38	unsigned long	count;
 39	unsigned long	*bitmap;
 40};
 41
 42struct cma *dma_contiguous_default_area;
 43
 44#ifdef CONFIG_CMA_SIZE_MBYTES
 45#define CMA_SIZE_MBYTES CONFIG_CMA_SIZE_MBYTES
 46#else
 47#define CMA_SIZE_MBYTES 0
 48#endif
 49
 50/*
 51 * Default global CMA area size can be defined in kernel's .config.
 52 * This is useful mainly for distro maintainers to create a kernel
 53 * that works correctly for most supported systems.
 54 * The size can be set in bytes or as a percentage of the total memory
 55 * in the system.
 56 *
 57 * Users, who want to set the size of global CMA area for their system
 58 * should use cma= kernel parameter.
 59 */
 60static const phys_addr_t size_bytes = CMA_SIZE_MBYTES * SZ_1M;
 61static phys_addr_t size_cmdline = -1;
 62
 63static int __init early_cma(char *p)
 64{
 65	pr_debug("%s(%s)\n", __func__, p);
 66	size_cmdline = memparse(p, &p);
 67	return 0;
 68}
 69early_param("cma", early_cma);
 70
 71#ifdef CONFIG_CMA_SIZE_PERCENTAGE
 72
 73static phys_addr_t __init __maybe_unused cma_early_percent_memory(void)
 74{
 75	struct memblock_region *reg;
 76	unsigned long total_pages = 0;
 77
 78	/*
 79	 * We cannot use memblock_phys_mem_size() here, because
 80	 * memblock_analyze() has not been called yet.
 81	 */
 82	for_each_memblock(memory, reg)
 83		total_pages += memblock_region_memory_end_pfn(reg) -
 84			       memblock_region_memory_base_pfn(reg);
 85
 86	return (total_pages * CONFIG_CMA_SIZE_PERCENTAGE / 100) << PAGE_SHIFT;
 87}
 88
 89#else
 90
 91static inline __maybe_unused phys_addr_t cma_early_percent_memory(void)
 92{
 93	return 0;
 94}
 95
 96#endif
 97
 98/**
 99 * dma_contiguous_reserve() - reserve area(s) for contiguous memory handling
100 * @limit: End address of the reserved memory (optional, 0 for any).
101 *
102 * This function reserves memory from early allocator. It should be
103 * called by arch specific code once the early allocator (memblock or bootmem)
104 * has been activated and all other subsystems have already allocated/reserved
105 * memory.
106 */
107void __init dma_contiguous_reserve(phys_addr_t limit)
108{
109	phys_addr_t selected_size = 0;
110
111	pr_debug("%s(limit %08lx)\n", __func__, (unsigned long)limit);
112
113	if (size_cmdline != -1) {
114		selected_size = size_cmdline;
115	} else {
116#ifdef CONFIG_CMA_SIZE_SEL_MBYTES
117		selected_size = size_bytes;
118#elif defined(CONFIG_CMA_SIZE_SEL_PERCENTAGE)
119		selected_size = cma_early_percent_memory();
120#elif defined(CONFIG_CMA_SIZE_SEL_MIN)
121		selected_size = min(size_bytes, cma_early_percent_memory());
122#elif defined(CONFIG_CMA_SIZE_SEL_MAX)
123		selected_size = max(size_bytes, cma_early_percent_memory());
124#endif
125	}
126
127	if (selected_size && !dma_contiguous_default_area) {
128		pr_debug("%s: reserving %ld MiB for global area\n", __func__,
129			 (unsigned long)selected_size / SZ_1M);
130
131		dma_contiguous_reserve_area(selected_size, 0, limit,
132					    &dma_contiguous_default_area);
133	}
134};
135
136static DEFINE_MUTEX(cma_mutex);
137
138static int __init cma_activate_area(struct cma *cma)
139{
140	int bitmap_size = BITS_TO_LONGS(cma->count) * sizeof(long);
141	unsigned long base_pfn = cma->base_pfn, pfn = base_pfn;
142	unsigned i = cma->count >> pageblock_order;
143	struct zone *zone;
144
145	cma->bitmap = kzalloc(bitmap_size, GFP_KERNEL);
146
147	if (!cma->bitmap)
148		return -ENOMEM;
149
150	WARN_ON_ONCE(!pfn_valid(pfn));
151	zone = page_zone(pfn_to_page(pfn));
152
153	do {
154		unsigned j;
155		base_pfn = pfn;
156		for (j = pageblock_nr_pages; j; --j, pfn++) {
157			WARN_ON_ONCE(!pfn_valid(pfn));
158			if (page_zone(pfn_to_page(pfn)) != zone)
159				return -EINVAL;
160		}
161		init_cma_reserved_pageblock(pfn_to_page(base_pfn));
162	} while (--i);
163
164	return 0;
165}
166
167static struct cma cma_areas[MAX_CMA_AREAS];
168static unsigned cma_area_count;
169
170static int __init cma_init_reserved_areas(void)
171{
172	int i;
173
174	for (i = 0; i < cma_area_count; i++) {
175		int ret = cma_activate_area(&cma_areas[i]);
176		if (ret)
177			return ret;
178	}
179
180	return 0;
181}
182core_initcall(cma_init_reserved_areas);
183
184/**
185 * dma_contiguous_reserve_area() - reserve custom contiguous area
186 * @size: Size of the reserved area (in bytes),
187 * @base: Base address of the reserved area optional, use 0 for any
188 * @limit: End address of the reserved memory (optional, 0 for any).
189 * @res_cma: Pointer to store the created cma region.
190 *
191 * This function reserves memory from early allocator. It should be
192 * called by arch specific code once the early allocator (memblock or bootmem)
193 * has been activated and all other subsystems have already allocated/reserved
194 * memory. This function allows to create custom reserved areas for specific
195 * devices.
196 */
197int __init dma_contiguous_reserve_area(phys_addr_t size, phys_addr_t base,
198				       phys_addr_t limit, struct cma **res_cma)
199{
200	struct cma *cma = &cma_areas[cma_area_count];
201	phys_addr_t alignment;
202	int ret = 0;
203
204	pr_debug("%s(size %lx, base %08lx, limit %08lx)\n", __func__,
205		 (unsigned long)size, (unsigned long)base,
206		 (unsigned long)limit);
207
208	/* Sanity checks */
209	if (cma_area_count == ARRAY_SIZE(cma_areas)) {
210		pr_err("Not enough slots for CMA reserved regions!\n");
211		return -ENOSPC;
212	}
213
214	if (!size)
215		return -EINVAL;
216
217	/* Sanitise input arguments */
218	alignment = PAGE_SIZE << max(MAX_ORDER - 1, pageblock_order);
219	base = ALIGN(base, alignment);
220	size = ALIGN(size, alignment);
221	limit &= ~(alignment - 1);
222
223	/* Reserve memory */
224	if (base) {
225		if (memblock_is_region_reserved(base, size) ||
226		    memblock_reserve(base, size) < 0) {
227			ret = -EBUSY;
228			goto err;
229		}
230	} else {
231		/*
232		 * Use __memblock_alloc_base() since
233		 * memblock_alloc_base() panic()s.
234		 */
235		phys_addr_t addr = __memblock_alloc_base(size, alignment, limit);
236		if (!addr) {
237			ret = -ENOMEM;
238			goto err;
239		} else {
240			base = addr;
241		}
242	}
243
244	/*
245	 * Each reserved area must be initialised later, when more kernel
246	 * subsystems (like slab allocator) are available.
247	 */
248	cma->base_pfn = PFN_DOWN(base);
249	cma->count = size >> PAGE_SHIFT;
250	*res_cma = cma;
251	cma_area_count++;
252
253	pr_info("CMA: reserved %ld MiB at %08lx\n", (unsigned long)size / SZ_1M,
254		(unsigned long)base);
255
256	/* Architecture specific contiguous memory fixup. */
257	dma_contiguous_early_fixup(base, size);
258	return 0;
259err:
260	pr_err("CMA: failed to reserve %ld MiB\n", (unsigned long)size / SZ_1M);
261	return ret;
262}
263
264/**
265 * dma_alloc_from_contiguous() - allocate pages from contiguous area
266 * @dev:   Pointer to device for which the allocation is performed.
267 * @count: Requested number of pages.
268 * @align: Requested alignment of pages (in PAGE_SIZE order).
269 *
270 * This function allocates memory buffer for specified device. It uses
271 * device specific contiguous memory area if available or the default
272 * global one. Requires architecture specific get_dev_cma_area() helper
273 * function.
274 */
275struct page *dma_alloc_from_contiguous(struct device *dev, int count,
276				       unsigned int align)
277{
278	unsigned long mask, pfn, pageno, start = 0;
279	struct cma *cma = dev_get_cma_area(dev);
280	struct page *page = NULL;
281	int ret;
282
283	if (!cma || !cma->count)
284		return NULL;
285
286	if (align > CONFIG_CMA_ALIGNMENT)
287		align = CONFIG_CMA_ALIGNMENT;
288
289	pr_debug("%s(cma %p, count %d, align %d)\n", __func__, (void *)cma,
290		 count, align);
291
292	if (!count)
293		return NULL;
294
295	mask = (1 << align) - 1;
296
297	mutex_lock(&cma_mutex);
298
299	for (;;) {
300		pageno = bitmap_find_next_zero_area(cma->bitmap, cma->count,
301						    start, count, mask);
302		if (pageno >= cma->count)
303			break;
304
305		pfn = cma->base_pfn + pageno;
306		ret = alloc_contig_range(pfn, pfn + count, MIGRATE_CMA);
307		if (ret == 0) {
308			bitmap_set(cma->bitmap, pageno, count);
309			page = pfn_to_page(pfn);
310			break;
311		} else if (ret != -EBUSY) {
312			break;
313		}
314		pr_debug("%s(): memory range at %p is busy, retrying\n",
315			 __func__, pfn_to_page(pfn));
316		/* try again with a bit different memory target */
317		start = pageno + mask + 1;
318	}
319
320	mutex_unlock(&cma_mutex);
321	pr_debug("%s(): returned %p\n", __func__, page);
322	return page;
323}
324
325/**
326 * dma_release_from_contiguous() - release allocated pages
327 * @dev:   Pointer to device for which the pages were allocated.
328 * @pages: Allocated pages.
329 * @count: Number of allocated pages.
330 *
331 * This function releases memory allocated by dma_alloc_from_contiguous().
332 * It returns false when provided pages do not belong to contiguous area and
333 * true otherwise.
334 */
335bool dma_release_from_contiguous(struct device *dev, struct page *pages,
336				 int count)
337{
338	struct cma *cma = dev_get_cma_area(dev);
339	unsigned long pfn;
340
341	if (!cma || !pages)
342		return false;
343
344	pr_debug("%s(page %p)\n", __func__, (void *)pages);
345
346	pfn = page_to_pfn(pages);
347
348	if (pfn < cma->base_pfn || pfn >= cma->base_pfn + cma->count)
349		return false;
350
351	VM_BUG_ON(pfn + count > cma->base_pfn + cma->count);
352
353	mutex_lock(&cma_mutex);
354	bitmap_clear(cma->bitmap, pfn - cma->base_pfn, count);
355	free_contig_range(pfn, count);
356	mutex_unlock(&cma_mutex);
357
358	return true;
359}