root/include/linux/cma.h

#ifndef __CMA_H__
#define __CMA_H__

/*
 * There is always at least global CMA area and a few optional
 * areas configured in kernel .config.
 */
#ifdef CONFIG_CMA_AREAS
#define MAX_CMA_AREAS   (1 + CONFIG_CMA_AREAS)

#else
#define MAX_CMA_AREAS   (0)

#endif

struct cma;

extern phys_addr_t cma_get_base(struct cma *cma);
extern unsigned long cma_get_size(struct cma *cma);

extern int __init cma_declare_contiguous(phys_addr_t base,
                        phys_addr_t size, phys_addr_t limit,
                        phys_addr_t alignment, unsigned int order_per_bit,
                        bool fixed, struct cma **res_cma);
extern int cma_init_reserved_mem(phys_addr_t base,
                                        phys_addr_t size, int order_per_bit,
                                        struct cma **res_cma);
extern struct page *cma_alloc(struct cma *cma, int count, unsigned int align);
extern bool cma_release(struct cma *cma, struct page *pages, int count);
#endif