// SPDX-License-Identifier: GPL-2.0+
/*
* Contiguous Memory Allocator for DMA mapping framework
* Copyright (c) 2010-2011 by Samsung Electronics.
* Written by:
* Marek Szyprowski <m.szyprowski@samsung.com>
* Michal Nazarewicz <mina86@mina86.com>
*
* Contiguous Memory Allocator
*
* The Contiguous Memory Allocator (CMA) makes it possible to
* allocate big contiguous chunks of memory after the system has
* booted.
*
* Why is it needed?
*
* Various devices on embedded systems have no scatter-getter and/or
* IO map support and require contiguous blocks of memory to
* operate. They include devices such as cameras, hardware video
* coders, etc.
*
* Such devices often require big memory buffers (a full HD frame
* is, for instance, more than 2 mega pixels large, i.e. more than 6
* MB of memory), which makes mechanisms such as kmalloc() or
* alloc_page() ineffective.
*
* At the same time, a solution where a big memory region is
* reserved for a device is suboptimal since often more memory is
* reserved then strictly required and, moreover, the memory is
* inaccessible to page system even if device drivers don't use it.
*
* CMA tries to solve this issue by operating on memory regions
* where only movable pages can be allocated from. This way, kernel
* can use the memory for pagecache and when device driver requests
* it, allocated pages can be migrated.
*/
#define pr_fmt(fmt) "cma: " fmt
#ifdef CONFIG_CMA_DEBUG
#ifndef DEBUG
# define DEBUG
#endif
#endif
#include <asm/page.h>
#include <linux/memblock.h>
#include <linux/err.h>
#include <linux/sizes.h>
#include <linux/dma-map-ops.h>
#include <linux/cma.h>
#ifdef CONFIG_CMA_SIZE_MBYTES
#define CMA_SIZE_MBYTES CONFIG_CMA_SIZE_MBYTES
#else
#define CMA_SIZE_MBYTES 0
#endif
struct cma *dma_contiguous_default_area;
/*
* Default global CMA area size can be defined in kernel's .config.
* This is useful mainly for distro maintainers to create a kernel
* that works correctly for most supported systems.
* The size can be set in bytes or as a percentage of the total memory
* in the system.
*
* Users, who want to set the size of global CMA area for their system
* should use cma= kernel parameter.
*/
static const phys_addr_t size_bytes __initconst =
(phys_addr_t)CMA_SIZE_MBYTES * SZ_1M;
static phys_addr_t size_cmdline __initdata = -1;
static phys_addr_t base_cmdline __initdata;
static phys_addr_t limit_cmdline __initdata;
static int __init early_cma(char *p)
{
if (!p) {
pr_err("Config string not provided\n");
return -EINVAL;
}
size_cmdline = memparse(p, &p);
if (*p != '@')
return 0;
base_cmdline = memparse(p + 1, &p);
if (*p != '-') {
limit_cmdline = base_cmdline + size_cmdline;
return 0;
}
limit_cmdline = memparse(p + 1, &p);
return 0;
}
early_param("cma", early_cma);
#ifdef CONFIG_DMA_PERNUMA_CMA
static struct cma *dma_contiguous_pernuma_area[MAX_NUMNODES];
static phys_addr_t pernuma_size_bytes __initdata;
static int __init early_cma_pernuma(char *p)
{
pernuma_size_bytes = memparse(p, &p);
return 0;
}
early_param("cma_pernuma", early_cma_pernuma);
#endif
#ifdef CONFIG_CMA_SIZE_PERCENTAGE
static phys_addr_t __init __maybe_unused cma_early_percent_memory(void)
{
unsigned long total_pages = PHYS_PFN(memblock_phys_mem_size());
return (total_pages * CONFIG_CMA_SIZE_PERCENTAGE / 100) << PAGE_SHIFT;
}
#else
static inline __maybe_unused phys_addr_t cma_early_percent_memory(void)
{
return 0;
}
#endif
#ifdef CONFIG_DMA_PERNUMA_CMA
void __init dma_pernuma_cma_reserve(void)
{
int nid;
if (!pernuma_size_bytes)
return;
for_each_online_node(nid) {
int ret;
char name[CMA_MAX_NAME];
struct cma **cma = &dma_contiguous_pernuma_area[nid];
snprintf(name, sizeof(name), "pernuma%d", nid);
ret = cma_declare_contiguous_nid(0, pernuma_size_bytes, 0, 0,
0, false, name, cma, nid);
if (ret) {
pr_warn("%s: reservation failed: err %d, node %d", __func__,
ret, nid);
continue;
}
pr_debug("%s: reserved %llu MiB on node %d\n", __func__,
(unsigned long long)pernuma_size_bytes / SZ_1M, nid);
}
}
#endif
/**
* dma_contiguous_reserve() - reserve area(s) for contiguous memory handling
* @limit: End address of the reserved memory (optional, 0 for any).
*
* This function reserves memory from early allocator. It should be
* called by arch specific code once the early allocator (memblock or bootmem)
* has been activated and all other subsystems have already allocated/reserved
* memory.
*/
void __init dma_contiguous_reserve(phys_addr_t limit)
{
phys_addr_t selected_size = 0;
phys_addr_t selected_base = 0;
phys_addr_t selected_limit = limit;
bool fixed = false;
pr_debug("%s(limit %08lx)\n", __func__, (unsigned long)limit);
if (size_cmdline != -1) {
selected_size = size_cmdline;
selected_base = base_cmdline;
selected_limit = min_not_zero(limit_cmdline, limit);
if (base_cmdline + size_cmdline == limit_cmdline)
fixed = true;
} else {
#ifdef CONFIG_CMA_SIZE_SEL_MBYTES
selected_size = size_bytes;
#elif defined(CONFIG_CMA_SIZE_SEL_PERCENTAGE)
selected_size = cma_early_percent_memory();
#elif defined(CONFIG_CMA_SIZE_SEL_MIN)
selected_size = min(size_bytes, cma_early_percent_memory());
#elif defined(CONFIG_CMA_SIZE_SEL_MAX)
selected_size = max(size_bytes, cma_early_percent_memory());
#endif
}
if (selected_size && !dma_contiguous_default_area) {
pr_debug("%s: reserving %ld MiB for global area\n", __func__,
(unsigned long)selected_size / SZ_1M);
dma_contiguous_reserve_area(selected_size, selected_base,
selected_limit,
&dma_contiguous_default_area,
fixed);
}
}
void __weak
dma_contiguous_early_fixup(phys_addr_t base, unsigned long size)
{
}
/**
* dma_contiguous_reserve_area() - reserve custom contiguous area
* @size: Size of the reserved area (in bytes),
* @base: Base address of the reserved area optional, use 0 for any
* @limit: End address of the reserved memory (optional, 0 for any).
* @res_cma: Pointer to store the created cma region.
* @fixed: hint about where to place the reserved area
*
* This function reserves memory from early allocator. It should be
* called by arch specific code once the early allocator (memblock or bootmem)
* has been activated and all other subsystems have already allocated/reserved
* memory. This function allows to create custom reserved areas for specific
* devices.
*
* If @fixed is true, reserve contiguous area at exactly @base. If false,
* reserve in range from @base to @limit.
*/
int __init dma_contiguous_reserve_area(phys_addr_t size, phys_addr_t base,
phys_addr_t limit, struct cma **res_cma,
bool fixed)
{
int ret;
ret = cma_declare_contiguous(base, size, limit, 0, 0, fixed,
"reserved", res_cma);
if (ret)
return ret;
/* Architecture specific contiguous memory fixup. */
dma_contiguous_early_fixup(cma_get_base(*res_cma),
cma_get_size(*res_cma));
return 0;
}
/**
* dma_alloc_from_contiguous() - allocate pages from contiguous area
* @dev: Pointer to device for which the allocation is performed.
* @count: Requested number of pages.
* @align: Requested alignment of pages (in PAGE_SIZE order).
* @no_warn: Avoid printing message about failed allocation.
*
* This function allocates memory buffer for specified device. It uses
* device specific contiguous memory area if available or the default
* global one. Requires architecture specific dev_get_cma_area() helper
* function.
*/
struct page *dma_alloc_from_contiguous(struct device *dev, size_t count,
unsigned int align, bool no_warn)
{
if (align > CONFIG_CMA_ALIGNMENT)
align = CONFIG_CMA_ALIGNMENT;
return cma_alloc(dev_get_cma_area(dev), count, align, no_warn);
}
/**
* dma_release_from_contiguous() - release allocated pages
* @dev: Pointer to device for which the pages were allocated.
* @pages: Allocated pages.
* @count: Number of allocated pages.
*
* This function releases memory allocated by dma_alloc_from_contiguous().
* It returns false when provided pages do not belong to contiguous area and
* true otherwise.
*/
bool dma_release_from_contiguous(struct device *dev, struct page *pages,
int count)
{
return cma_release(dev_get_cma_area(dev), pages, count);
}
static struct page *cma_alloc_aligned(struct cma *cma, size_t size, gfp_t gfp)
{
unsigned int align = min(get_order(size), CONFIG_CMA_ALIGNMENT);
return cma_alloc(cma, size >> PAGE_SHIFT, align, gfp & __GFP_NOWARN);
}
/**
* dma_alloc_contiguous() - allocate contiguous pages
* @dev: Pointer to device for which the allocation is performed.
* @size: Requested allocation size.
* @gfp: Allocation flags.
*
* tries to use device specific contiguous memory area if available, or it
* tries to use per-numa cma, if the allocation fails, it will fallback to
* try default global one.
*
* Note that it bypass one-page size of allocations from the per-numa and
* global area as the addresses within one page are always contiguous, so
* there is no need to waste CMA pages for that kind; it also helps reduce
* fragmentations.
*/
struct page *dma_alloc_contiguous(struct device *dev, size_t size, gfp_t gfp)
{
#ifdef CONFIG_DMA_PERNUMA_CMA
int nid = dev_to_node(dev);
#endif
/* CMA can be used only in the context which permits sleeping */
if (!gfpflags_allow_blocking(gfp))
return NULL;
if (dev->cma_area)
return cma_alloc_aligned(dev->cma_area, size, gfp);
if (size <= PAGE_SIZE)
return NULL;
#ifdef CONFIG_DMA_PERNUMA_CMA
if (nid != NUMA_NO_NODE && !(gfp & (GFP_DMA | GFP_DMA32))) {
struct cma *cma = dma_contiguous_pernuma_area[nid];
struct page *page;
if (cma) {
page = cma_alloc_aligned(cma, size, gfp);
if (page)
return page;
}
}
#endif
if (!dma_contiguous_default_area)
return NULL;
return cma_alloc_aligned(dma_contiguous_default_area, size, gfp);
}
/**
* dma_free_contiguous() - release allocated pages
* @dev: Pointer to device for which the pages were allocated.
* @page: Pointer to the allocated pages.
* @size: Size of allocated pages.
*
* This function releases memory allocated by dma_alloc_contiguous(). As the
* cma_release returns false when provided pages do not belong to contiguous
* area and true otherwise, this function then does a fallback __free_pages()
* upon a false-return.
*/
void dma_free_contiguous(struct device *dev, struct page *page, size_t size)
{
unsigned int count = PAGE_ALIGN(size) >> PAGE_SHIFT;
/* if dev has its own cma, free page from there */
if (dev->cma_area) {
if (cma_release(dev->cma_area, page, count))
return;
} else {
/*
* otherwise, page is from either per-numa cma or default cma
*/
#ifdef CONFIG_DMA_PERNUMA_CMA
if (cma_release(dma_contiguous_pernuma_area[page_to_nid(page)],
page, count))
return;
#endif
if (cma_release(dma_contiguous_default_area, page, count))
return;
}
/* not in any cma, free from buddy */
__free_pages(page, get_order(size));
}
/*
* 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>
#undef pr_fmt
#define pr_fmt(fmt) fmt
static int rmem_cma_device_init(struct reserved_mem *rmem, struct device *dev)
{
dev->cma_area = rmem->priv;
return 0;
}
static void rmem_cma_device_release(struct reserved_mem *rmem,
struct device *dev)
{
dev->cma_area = NULL;
}
static const struct reserved_mem_ops rmem_cma_ops = {
.device_init = rmem_cma_device_init,
.device_release = rmem_cma_device_release,
};
static int __init rmem_cma_setup(struct reserved_mem *rmem)
{
unsigned long node = rmem->fdt_node;
bool default_cma = of_get_flat_dt_prop(node, "linux,cma-default", NULL);
struct cma *cma;
int err;
if (size_cmdline != -1 && default_cma) {
pr_info("Reserved memory: bypass %s node, using cmdline CMA params instead\n",
rmem->name);
return -EBUSY;
}
if (!of_get_flat_dt_prop(node, "reusable", NULL) ||
of_get_flat_dt_prop(node, "no-map", NULL))
return -EINVAL;
if (!IS_ALIGNED(rmem->base | rmem->size, CMA_MIN_ALIGNMENT_BYTES)) {
pr_err("Reserved memory: incorrect alignment of CMA region\n");
return -EINVAL;
}
err = cma_init_reserved_mem(rmem->base, rmem->size, 0, rmem->name, &cma);
if (err) {
pr_err("Reserved memory: unable to setup CMA region\n");
return err;
}
/* Architecture specific contiguous memory fixup. */
dma_contiguous_early_fixup(rmem->base, rmem->size);
if (default_cma)
dma_contiguous_default_area = cma;
rmem->ops = &rmem_cma_ops;
rmem->priv = cma;
pr_info("Reserved memory: created CMA memory pool at %pa, size %ld MiB\n",
&rmem->base, (unsigned long)rmem->size / SZ_1M);
return 0;
}
RESERVEDMEM_OF_DECLARE(cma, "shared-dma-pool", rmem_cma_setup);
#endif
