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/* SPDX-License-Identifier: GPL-2.0-only */
#ifndef _ASM_POWERPC_RTAS_WORK_AREA_H
#define _ASM_POWERPC_RTAS_WORK_AREA_H
#include <linux/build_bug.h>
#include <linux/sizes.h>
#include <linux/types.h>
#include <asm/page.h>
/**
* struct rtas_work_area - RTAS work area descriptor.
*
* Descriptor for a "work area" in PAPR terminology that satisfies
* RTAS addressing requirements.
*/
struct rtas_work_area {
/* private: Use the APIs provided below. */
char *buf;
size_t size;
};
enum {
/* Maximum allocation size, enforced at build time. */
RTAS_WORK_AREA_MAX_ALLOC_SZ = SZ_128K,
};
/**
* rtas_work_area_alloc() - Acquire a work area of the requested size.
* @size_: Allocation size. Must be compile-time constant and not more
* than %RTAS_WORK_AREA_MAX_ALLOC_SZ.
*
* Allocate a buffer suitable for passing to RTAS functions that have
* a memory address parameter, often (but not always) referred to as a
* "work area" in PAPR. Although callers are allowed to block while
* holding a work area, the amount of memory reserved for this purpose
* is limited, and allocations should be short-lived. A good guideline
* is to release any allocated work area before returning from a
* system call.
*
* This function does not fail. It blocks until the allocation
* succeeds. To prevent deadlocks, callers are discouraged from
* allocating more than one work area simultaneously in a single task
* context.
*
* Context: This function may sleep.
* Return: A &struct rtas_work_area descriptor for the allocated work area.
*/
#define rtas_work_area_alloc(size_) ({ \
static_assert(__builtin_constant_p(size_)); \
static_assert((size_) > 0); \
static_assert((size_) <= RTAS_WORK_AREA_MAX_ALLOC_SZ); \
__rtas_work_area_alloc(size_); \
})
/*
* Do not call __rtas_work_area_alloc() directly. Use
* rtas_work_area_alloc().
*/
struct rtas_work_area *__rtas_work_area_alloc(size_t size);
/**
* rtas_work_area_free() - Release a work area.
* @area: Work area descriptor as returned from rtas_work_area_alloc().
*
* Return a work area buffer to the pool.
*/
void rtas_work_area_free(struct rtas_work_area *area);
static inline char *rtas_work_area_raw_buf(const struct rtas_work_area *area)
{
return area->buf;
}
static inline size_t rtas_work_area_size(const struct rtas_work_area *area)
{
return area->size;
}
static inline phys_addr_t rtas_work_area_phys(const struct rtas_work_area *area)
{
return __pa(area->buf);
}
/*
* Early setup for the work area allocator. Call from
* rtas_initialize() only.
*/
#ifdef CONFIG_PPC_PSERIES
void rtas_work_area_reserve_arena(phys_addr_t limit);
#else /* CONFIG_PPC_PSERIES */
static inline void rtas_work_area_reserve_arena(phys_addr_t limit) {}
#endif /* CONFIG_PPC_PSERIES */
#endif /* _ASM_POWERPC_RTAS_WORK_AREA_H */
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