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