| From dhobsong@igel.co.jp Mon Oct 29 00:52:19 2012 |
| From: Damian Hobson-Garcia <dhobsong@igel.co.jp> |
| Date: Mon, 29 Oct 2012 16:50:30 +0900 |
| Subject: [PATCH v2 13/58] drivers: add Contiguous Memory Allocator |
| To: greg@kroah.com, laurent.pinchart@ideasonboard.com, horms@verge.net.au |
| Cc: ltsi-dev@lists.linuxfoundation.org, dhobsong@igel.co.jp |
| Message-ID: <1351497075-32717-14-git-send-email-dhobsong@igel.co.jp> |
| |
| |
| From: Marek Szyprowski <m.szyprowski@samsung.com> |
| |
| The Contiguous Memory Allocator is a set of helper functions for DMA |
| mapping framework that improves allocations of contiguous memory chunks. |
| |
| CMA grabs memory on system boot, marks it with MIGRATE_CMA migrate type |
| and gives back to the system. Kernel is allowed to allocate only movable |
| pages within CMA's managed memory so that it can be used for example for |
| page cache when DMA mapping do not use it. On |
| dma_alloc_from_contiguous() request such pages are migrated out of CMA |
| area to free required contiguous block and fulfill the request. This |
| allows to allocate large contiguous chunks of memory at any time |
| assuming that there is enough free memory available in the system. |
| |
| This code is heavily based on earlier works by Michal Nazarewicz. |
| |
| Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> |
| Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com> |
| Signed-off-by: Michal Nazarewicz <mina86@mina86.com> |
| Acked-by: Arnd Bergmann <arnd@arndb.de> |
| Tested-by: Rob Clark <rob.clark@linaro.org> |
| Tested-by: Ohad Ben-Cohen <ohad@wizery.com> |
| Tested-by: Benjamin Gaignard <benjamin.gaignard@linaro.org> |
| Tested-by: Robert Nelson <robertcnelson@gmail.com> |
| Tested-by: Barry Song <Baohua.Song@csr.com> |
| (cherry picked from commit c64be2bb1c6eb43c838b2c6d57b074078be208dd) |
| |
| Signed-off-by: Damian Hobson-Garcia <dhobsong@igel.co.jp> |
| Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> |
| --- |
| Documentation/kernel-parameters.txt | 5 |
| arch/Kconfig | 3 |
| drivers/base/Kconfig | 89 +++++++ |
| drivers/base/Makefile | 1 |
| drivers/base/dma-contiguous.c | 401 +++++++++++++++++++++++++++++++++++ |
| include/asm-generic/dma-contiguous.h | 28 ++ |
| include/linux/device.h | 4 |
| include/linux/dma-contiguous.h | 110 +++++++++ |
| 8 files changed, 641 insertions(+) |
| create mode 100644 drivers/base/dma-contiguous.c |
| create mode 100644 include/asm-generic/dma-contiguous.h |
| create mode 100644 include/linux/dma-contiguous.h |
| |
| --- a/Documentation/kernel-parameters.txt |
| +++ b/Documentation/kernel-parameters.txt |
| @@ -508,6 +508,11 @@ bytes respectively. Such letter suffixes |
| Also note the kernel might malfunction if you disable |
| some critical bits. |
| |
| + cma=nn[MG] [ARM,KNL] |
| + Sets the size of kernel global memory area for contiguous |
| + memory allocations. For more information, see |
| + include/linux/dma-contiguous.h |
| + |
| cmo_free_hint= [PPC] Format: { yes | no } |
| Specify whether pages are marked as being inactive |
| when they are freed. This is used in CMO environments |
| --- a/arch/Kconfig |
| +++ b/arch/Kconfig |
| @@ -145,6 +145,9 @@ config HAVE_ARCH_TRACEHOOK |
| config HAVE_DMA_ATTRS |
| bool |
| |
| +config HAVE_DMA_CONTIGUOUS |
| + bool |
| + |
| config USE_GENERIC_SMP_HELPERS |
| bool |
| |
| --- a/drivers/base/Kconfig |
| +++ b/drivers/base/Kconfig |
| @@ -192,4 +192,93 @@ config DMA_SHARED_BUFFER |
| APIs extension; the file's descriptor can then be passed on to other |
| driver. |
| |
| +config CMA |
| + bool "Contiguous Memory Allocator (EXPERIMENTAL)" |
| + depends on HAVE_DMA_CONTIGUOUS && HAVE_MEMBLOCK && EXPERIMENTAL |
| + select MIGRATION |
| + help |
| + This enables the Contiguous Memory Allocator which allows drivers |
| + to allocate big physically-contiguous blocks of memory for use with |
| + hardware components that do not support I/O map nor scatter-gather. |
| + |
| + For more information see <include/linux/dma-contiguous.h>. |
| + If unsure, say "n". |
| + |
| +if CMA |
| + |
| +config CMA_DEBUG |
| + bool "CMA debug messages (DEVELOPMENT)" |
| + depends on DEBUG_KERNEL |
| + help |
| + Turns on debug messages in CMA. This produces KERN_DEBUG |
| + messages for every CMA call as well as various messages while |
| + processing calls such as dma_alloc_from_contiguous(). |
| + This option does not affect warning and error messages. |
| + |
| +comment "Default contiguous memory area size:" |
| + |
| +config CMA_SIZE_MBYTES |
| + int "Size in Mega Bytes" |
| + depends on !CMA_SIZE_SEL_PERCENTAGE |
| + default 16 |
| + help |
| + Defines the size (in MiB) of the default memory area for Contiguous |
| + Memory Allocator. |
| + |
| +config CMA_SIZE_PERCENTAGE |
| + int "Percentage of total memory" |
| + depends on !CMA_SIZE_SEL_MBYTES |
| + default 10 |
| + help |
| + Defines the size of the default memory area for Contiguous Memory |
| + Allocator as a percentage of the total memory in the system. |
| + |
| +choice |
| + prompt "Selected region size" |
| + default CMA_SIZE_SEL_ABSOLUTE |
| + |
| +config CMA_SIZE_SEL_MBYTES |
| + bool "Use mega bytes value only" |
| + |
| +config CMA_SIZE_SEL_PERCENTAGE |
| + bool "Use percentage value only" |
| + |
| +config CMA_SIZE_SEL_MIN |
| + bool "Use lower value (minimum)" |
| + |
| +config CMA_SIZE_SEL_MAX |
| + bool "Use higher value (maximum)" |
| + |
| +endchoice |
| + |
| +config CMA_ALIGNMENT |
| + int "Maximum PAGE_SIZE order of alignment for contiguous buffers" |
| + range 4 9 |
| + default 8 |
| + help |
| + DMA mapping framework by default aligns all buffers to the smallest |
| + PAGE_SIZE order which is greater than or equal to the requested buffer |
| + size. This works well for buffers up to a few hundreds kilobytes, but |
| + for larger buffers it just a memory waste. With this parameter you can |
| + specify the maximum PAGE_SIZE order for contiguous buffers. Larger |
| + buffers will be aligned only to this specified order. The order is |
| + expressed as a power of two multiplied by the PAGE_SIZE. |
| + |
| + For example, if your system defaults to 4KiB pages, the order value |
| + of 8 means that the buffers will be aligned up to 1MiB only. |
| + |
| + If unsure, leave the default value "8". |
| + |
| +config CMA_AREAS |
| + int "Maximum count of the CMA device-private areas" |
| + default 7 |
| + help |
| + CMA allows to create CMA areas for particular devices. This parameter |
| + sets the maximum number of such device private CMA areas in the |
| + system. |
| + |
| + If unsure, leave the default value "7". |
| + |
| +endif |
| + |
| endmenu |
| --- a/drivers/base/Makefile |
| +++ b/drivers/base/Makefile |
| @@ -6,6 +6,7 @@ obj-y := core.o bus.o dd.o syscore.o \ |
| attribute_container.o transport_class.o \ |
| topology.o |
| obj-$(CONFIG_DEVTMPFS) += devtmpfs.o |
| +obj-$(CONFIG_CMA) += dma-contiguous.o |
| obj-y += power/ |
| obj-$(CONFIG_HAS_DMA) += dma-mapping.o |
| obj-$(CONFIG_HAVE_GENERIC_DMA_COHERENT) += dma-coherent.o |
| --- /dev/null |
| +++ b/drivers/base/dma-contiguous.c |
| @@ -0,0 +1,401 @@ |
| +/* |
| + * 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> |
| + * |
| + * This program is free software; you can redistribute it and/or |
| + * modify it under the terms of the GNU General Public License as |
| + * published by the Free Software Foundation; either version 2 of the |
| + * License or (at your optional) any later version of the license. |
| + */ |
| + |
| +#define pr_fmt(fmt) "cma: " fmt |
| + |
| +#ifdef CONFIG_CMA_DEBUG |
| +#ifndef DEBUG |
| +# define DEBUG |
| +#endif |
| +#endif |
| + |
| +#include <asm/page.h> |
| +#include <asm/dma-contiguous.h> |
| + |
| +#include <linux/memblock.h> |
| +#include <linux/err.h> |
| +#include <linux/mm.h> |
| +#include <linux/mutex.h> |
| +#include <linux/page-isolation.h> |
| +#include <linux/slab.h> |
| +#include <linux/swap.h> |
| +#include <linux/mm_types.h> |
| +#include <linux/dma-contiguous.h> |
| + |
| +#ifndef SZ_1M |
| +#define SZ_1M (1 << 20) |
| +#endif |
| + |
| +struct cma { |
| + unsigned long base_pfn; |
| + unsigned long count; |
| + unsigned long *bitmap; |
| +}; |
| + |
| +struct cma *dma_contiguous_default_area; |
| + |
| +#ifdef CONFIG_CMA_SIZE_MBYTES |
| +#define CMA_SIZE_MBYTES CONFIG_CMA_SIZE_MBYTES |
| +#else |
| +#define CMA_SIZE_MBYTES 0 |
| +#endif |
| + |
| +/* |
| + * Default global CMA area size can be defined in kernel's .config. |
| + * This is usefull 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 unsigned long size_bytes = CMA_SIZE_MBYTES * SZ_1M; |
| +static long size_cmdline = -1; |
| + |
| +static int __init early_cma(char *p) |
| +{ |
| + pr_debug("%s(%s)\n", __func__, p); |
| + size_cmdline = memparse(p, &p); |
| + return 0; |
| +} |
| +early_param("cma", early_cma); |
| + |
| +#ifdef CONFIG_CMA_SIZE_PERCENTAGE |
| + |
| +static unsigned long __init __maybe_unused cma_early_percent_memory(void) |
| +{ |
| + struct memblock_region *reg; |
| + unsigned long total_pages = 0; |
| + |
| + /* |
| + * We cannot use memblock_phys_mem_size() here, because |
| + * memblock_analyze() has not been called yet. |
| + */ |
| + for_each_memblock(memory, reg) |
| + total_pages += memblock_region_memory_end_pfn(reg) - |
| + memblock_region_memory_base_pfn(reg); |
| + |
| + return (total_pages * CONFIG_CMA_SIZE_PERCENTAGE / 100) << PAGE_SHIFT; |
| +} |
| + |
| +#else |
| + |
| +static inline __maybe_unused unsigned long cma_early_percent_memory(void) |
| +{ |
| + return 0; |
| +} |
| + |
| +#endif |
| + |
| +/** |
| + * dma_contiguous_reserve() - reserve area 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) |
| +{ |
| + unsigned long selected_size = 0; |
| + |
| + pr_debug("%s(limit %08lx)\n", __func__, (unsigned long)limit); |
| + |
| + if (size_cmdline != -1) { |
| + selected_size = size_cmdline; |
| + } 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) { |
| + pr_debug("%s: reserving %ld MiB for global area\n", __func__, |
| + selected_size / SZ_1M); |
| + |
| + dma_declare_contiguous(NULL, selected_size, 0, limit); |
| + } |
| +}; |
| + |
| +static DEFINE_MUTEX(cma_mutex); |
| + |
| +static __init int cma_activate_area(unsigned long base_pfn, unsigned long count) |
| +{ |
| + unsigned long pfn = base_pfn; |
| + unsigned i = count >> pageblock_order; |
| + struct zone *zone; |
| + |
| + WARN_ON_ONCE(!pfn_valid(pfn)); |
| + zone = page_zone(pfn_to_page(pfn)); |
| + |
| + do { |
| + unsigned j; |
| + base_pfn = pfn; |
| + for (j = pageblock_nr_pages; j; --j, pfn++) { |
| + WARN_ON_ONCE(!pfn_valid(pfn)); |
| + if (page_zone(pfn_to_page(pfn)) != zone) |
| + return -EINVAL; |
| + } |
| + init_cma_reserved_pageblock(pfn_to_page(base_pfn)); |
| + } while (--i); |
| + return 0; |
| +} |
| + |
| +static __init struct cma *cma_create_area(unsigned long base_pfn, |
| + unsigned long count) |
| +{ |
| + int bitmap_size = BITS_TO_LONGS(count) * sizeof(long); |
| + struct cma *cma; |
| + int ret = -ENOMEM; |
| + |
| + pr_debug("%s(base %08lx, count %lx)\n", __func__, base_pfn, count); |
| + |
| + cma = kmalloc(sizeof *cma, GFP_KERNEL); |
| + if (!cma) |
| + return ERR_PTR(-ENOMEM); |
| + |
| + cma->base_pfn = base_pfn; |
| + cma->count = count; |
| + cma->bitmap = kzalloc(bitmap_size, GFP_KERNEL); |
| + |
| + if (!cma->bitmap) |
| + goto no_mem; |
| + |
| + ret = cma_activate_area(base_pfn, count); |
| + if (ret) |
| + goto error; |
| + |
| + pr_debug("%s: returned %p\n", __func__, (void *)cma); |
| + return cma; |
| + |
| +error: |
| + kfree(cma->bitmap); |
| +no_mem: |
| + kfree(cma); |
| + return ERR_PTR(ret); |
| +} |
| + |
| +static struct cma_reserved { |
| + phys_addr_t start; |
| + unsigned long size; |
| + struct device *dev; |
| +} cma_reserved[MAX_CMA_AREAS] __initdata; |
| +static unsigned cma_reserved_count __initdata; |
| + |
| +static int __init cma_init_reserved_areas(void) |
| +{ |
| + struct cma_reserved *r = cma_reserved; |
| + unsigned i = cma_reserved_count; |
| + |
| + pr_debug("%s()\n", __func__); |
| + |
| + for (; i; --i, ++r) { |
| + struct cma *cma; |
| + cma = cma_create_area(PFN_DOWN(r->start), |
| + r->size >> PAGE_SHIFT); |
| + if (!IS_ERR(cma)) |
| + dev_set_cma_area(r->dev, cma); |
| + } |
| + return 0; |
| +} |
| +core_initcall(cma_init_reserved_areas); |
| + |
| +/** |
| + * dma_declare_contiguous() - reserve area for contiguous memory handling |
| + * for particular device |
| + * @dev: Pointer to device structure. |
| + * @size: Size of the reserved memory. |
| + * @base: Start address of the reserved memory (optional, 0 for any). |
| + * @limit: End address of the reserved memory (optional, 0 for any). |
| + * |
| + * This function reserves memory for specified device. It should be |
| + * called by board specific code when early allocator (memblock or bootmem) |
| + * is still activate. |
| + */ |
| +int __init dma_declare_contiguous(struct device *dev, unsigned long size, |
| + phys_addr_t base, phys_addr_t limit) |
| +{ |
| + struct cma_reserved *r = &cma_reserved[cma_reserved_count]; |
| + unsigned long alignment; |
| + |
| + pr_debug("%s(size %lx, base %08lx, limit %08lx)\n", __func__, |
| + (unsigned long)size, (unsigned long)base, |
| + (unsigned long)limit); |
| + |
| + /* Sanity checks */ |
| + if (cma_reserved_count == ARRAY_SIZE(cma_reserved)) { |
| + pr_err("Not enough slots for CMA reserved regions!\n"); |
| + return -ENOSPC; |
| + } |
| + |
| + if (!size) |
| + return -EINVAL; |
| + |
| + /* Sanitise input arguments */ |
| + alignment = PAGE_SIZE << max(MAX_ORDER, pageblock_order); |
| + base = ALIGN(base, alignment); |
| + size = ALIGN(size, alignment); |
| + limit &= ~(alignment - 1); |
| + |
| + /* Reserve memory */ |
| + if (base) { |
| + if (memblock_is_region_reserved(base, size) || |
| + memblock_reserve(base, size) < 0) { |
| + base = -EBUSY; |
| + goto err; |
| + } |
| + } else { |
| + /* |
| + * Use __memblock_alloc_base() since |
| + * memblock_alloc_base() panic()s. |
| + */ |
| + phys_addr_t addr = __memblock_alloc_base(size, alignment, limit); |
| + if (!addr) { |
| + base = -ENOMEM; |
| + goto err; |
| + } else if (addr + size > ~(unsigned long)0) { |
| + memblock_free(addr, size); |
| + base = -EINVAL; |
| + goto err; |
| + } else { |
| + base = addr; |
| + } |
| + } |
| + |
| + /* |
| + * Each reserved area must be initialised later, when more kernel |
| + * subsystems (like slab allocator) are available. |
| + */ |
| + r->start = base; |
| + r->size = size; |
| + r->dev = dev; |
| + cma_reserved_count++; |
| + pr_info("CMA: reserved %ld MiB at %08lx\n", size / SZ_1M, |
| + (unsigned long)base); |
| + |
| + /* Architecture specific contiguous memory fixup. */ |
| + dma_contiguous_early_fixup(base, size); |
| + return 0; |
| +err: |
| + pr_err("CMA: failed to reserve %ld MiB\n", size / SZ_1M); |
| + return base; |
| +} |
| + |
| +/** |
| + * 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). |
| + * |
| + * 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 get_dev_cma_area() helper |
| + * function. |
| + */ |
| +struct page *dma_alloc_from_contiguous(struct device *dev, int count, |
| + unsigned int align) |
| +{ |
| + unsigned long mask, pfn, pageno, start = 0; |
| + struct cma *cma = dev_get_cma_area(dev); |
| + int ret; |
| + |
| + if (!cma || !cma->count) |
| + return NULL; |
| + |
| + if (align > CONFIG_CMA_ALIGNMENT) |
| + align = CONFIG_CMA_ALIGNMENT; |
| + |
| + pr_debug("%s(cma %p, count %d, align %d)\n", __func__, (void *)cma, |
| + count, align); |
| + |
| + if (!count) |
| + return NULL; |
| + |
| + mask = (1 << align) - 1; |
| + |
| + mutex_lock(&cma_mutex); |
| + |
| + for (;;) { |
| + pageno = bitmap_find_next_zero_area(cma->bitmap, cma->count, |
| + start, count, mask); |
| + if (pageno >= cma->count) { |
| + ret = -ENOMEM; |
| + goto error; |
| + } |
| + |
| + pfn = cma->base_pfn + pageno; |
| + ret = alloc_contig_range(pfn, pfn + count, MIGRATE_CMA); |
| + if (ret == 0) { |
| + bitmap_set(cma->bitmap, pageno, count); |
| + break; |
| + } else if (ret != -EBUSY) { |
| + goto error; |
| + } |
| + pr_debug("%s(): memory range at %p is busy, retrying\n", |
| + __func__, pfn_to_page(pfn)); |
| + /* try again with a bit different memory target */ |
| + start = pageno + mask + 1; |
| + } |
| + |
| + mutex_unlock(&cma_mutex); |
| + |
| + pr_debug("%s(): returned %p\n", __func__, pfn_to_page(pfn)); |
| + return pfn_to_page(pfn); |
| +error: |
| + mutex_unlock(&cma_mutex); |
| + return NULL; |
| +} |
| + |
| +/** |
| + * 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) |
| +{ |
| + struct cma *cma = dev_get_cma_area(dev); |
| + unsigned long pfn; |
| + |
| + if (!cma || !pages) |
| + return false; |
| + |
| + pr_debug("%s(page %p)\n", __func__, (void *)pages); |
| + |
| + pfn = page_to_pfn(pages); |
| + |
| + if (pfn < cma->base_pfn || pfn >= cma->base_pfn + cma->count) |
| + return false; |
| + |
| + VM_BUG_ON(pfn + count > cma->base_pfn + cma->count); |
| + |
| + mutex_lock(&cma_mutex); |
| + bitmap_clear(cma->bitmap, pfn - cma->base_pfn, count); |
| + free_contig_range(pfn, count); |
| + mutex_unlock(&cma_mutex); |
| + |
| + return true; |
| +} |
| --- /dev/null |
| +++ b/include/asm-generic/dma-contiguous.h |
| @@ -0,0 +1,28 @@ |
| +#ifndef ASM_DMA_CONTIGUOUS_H |
| +#define ASM_DMA_CONTIGUOUS_H |
| + |
| +#ifdef __KERNEL__ |
| +#ifdef CONFIG_CMA |
| + |
| +#include <linux/device.h> |
| +#include <linux/dma-contiguous.h> |
| + |
| +static inline struct cma *dev_get_cma_area(struct device *dev) |
| +{ |
| + if (dev && dev->cma_area) |
| + return dev->cma_area; |
| + return dma_contiguous_default_area; |
| +} |
| + |
| +static inline void dev_set_cma_area(struct device *dev, struct cma *cma) |
| +{ |
| + if (dev) |
| + dev->cma_area = cma; |
| + if (!dev || !dma_contiguous_default_area) |
| + dma_contiguous_default_area = cma; |
| +} |
| + |
| +#endif |
| +#endif |
| + |
| +#endif |
| --- a/include/linux/device.h |
| +++ b/include/linux/device.h |
| @@ -661,6 +661,10 @@ struct device { |
| |
| struct dma_coherent_mem *dma_mem; /* internal for coherent mem |
| override */ |
| +#ifdef CONFIG_CMA |
| + struct cma *cma_area; /* contiguous memory area for dma |
| + allocations */ |
| +#endif |
| /* arch specific additions */ |
| struct dev_archdata archdata; |
| |
| --- /dev/null |
| +++ b/include/linux/dma-contiguous.h |
| @@ -0,0 +1,110 @@ |
| +#ifndef __LINUX_CMA_H |
| +#define __LINUX_CMA_H |
| + |
| +/* |
| + * 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> |
| + * |
| + * This program is free software; you can redistribute it and/or |
| + * modify it under the terms of the GNU General Public License as |
| + * published by the Free Software Foundation; either version 2 of the |
| + * License or (at your optional) any later version of the license. |
| + */ |
| + |
| +/* |
| + * 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 then 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. |
| + * |
| + * Driver usage |
| + * |
| + * CMA should not be used by the device drivers directly. It is |
| + * only a helper framework for dma-mapping subsystem. |
| + * |
| + * For more information, see kernel-docs in drivers/base/dma-contiguous.c |
| + */ |
| + |
| +#ifdef __KERNEL__ |
| + |
| +struct cma; |
| +struct page; |
| +struct device; |
| + |
| +#ifdef CONFIG_CMA |
| + |
| +/* |
| + * There is always at least global CMA area and a few optional device |
| + * private areas configured in kernel .config. |
| + */ |
| +#define MAX_CMA_AREAS (1 + CONFIG_CMA_AREAS) |
| + |
| +extern struct cma *dma_contiguous_default_area; |
| + |
| +void dma_contiguous_reserve(phys_addr_t addr_limit); |
| +int dma_declare_contiguous(struct device *dev, unsigned long size, |
| + phys_addr_t base, phys_addr_t limit); |
| + |
| +struct page *dma_alloc_from_contiguous(struct device *dev, int count, |
| + unsigned int order); |
| +bool dma_release_from_contiguous(struct device *dev, struct page *pages, |
| + int count); |
| + |
| +#else |
| + |
| +#define MAX_CMA_AREAS (0) |
| + |
| +static inline void dma_contiguous_reserve(phys_addr_t limit) { } |
| + |
| +static inline |
| +int dma_declare_contiguous(struct device *dev, unsigned long size, |
| + phys_addr_t base, phys_addr_t limit) |
| +{ |
| + return -ENOSYS; |
| +} |
| + |
| +static inline |
| +struct page *dma_alloc_from_contiguous(struct device *dev, int count, |
| + unsigned int order) |
| +{ |
| + return NULL; |
| +} |
| + |
| +static inline |
| +bool dma_release_from_contiguous(struct device *dev, struct page *pages, |
| + int count) |
| +{ |
| + return false; |
| +} |
| + |
| +#endif |
| + |
| +#endif |
| + |
| +#endif |