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| 1 | /* SPDX-License-Identifier: GPL-2.0-only */ |
|---|---|
| 2 | #ifndef _ASM_POWERPC_RTAS_WORK_AREA_H |
| 3 | #define _ASM_POWERPC_RTAS_WORK_AREA_H |
| 4 | |
| 5 | #include <linux/build_bug.h> |
| 6 | #include <linux/sizes.h> |
| 7 | #include <linux/types.h> |
| 8 | |
| 9 | #include <asm/page.h> |
| 10 | |
| 11 | /** |
| 12 | * struct rtas_work_area - RTAS work area descriptor. |
| 13 | * |
| 14 | * Descriptor for a "work area" in PAPR terminology that satisfies |
| 15 | * RTAS addressing requirements. |
| 16 | */ |
| 17 | struct rtas_work_area { |
| 18 | /* private: Use the APIs provided below. */ |
| 19 | char *buf; |
| 20 | size_t size; |
| 21 | }; |
| 22 | |
| 23 | enum { |
| 24 | /* Maximum allocation size, enforced at build time. */ |
| 25 | RTAS_WORK_AREA_MAX_ALLOC_SZ = SZ_128K, |
| 26 | }; |
| 27 | |
| 28 | /** |
| 29 | * rtas_work_area_alloc() - Acquire a work area of the requested size. |
| 30 | * @size_: Allocation size. Must be compile-time constant and not more |
| 31 | * than %RTAS_WORK_AREA_MAX_ALLOC_SZ. |
| 32 | * |
| 33 | * Allocate a buffer suitable for passing to RTAS functions that have |
| 34 | * a memory address parameter, often (but not always) referred to as a |
| 35 | * "work area" in PAPR. Although callers are allowed to block while |
| 36 | * holding a work area, the amount of memory reserved for this purpose |
| 37 | * is limited, and allocations should be short-lived. A good guideline |
| 38 | * is to release any allocated work area before returning from a |
| 39 | * system call. |
| 40 | * |
| 41 | * This function does not fail. It blocks until the allocation |
| 42 | * succeeds. To prevent deadlocks, callers are discouraged from |
| 43 | * allocating more than one work area simultaneously in a single task |
| 44 | * context. |
| 45 | * |
| 46 | * Context: This function may sleep. |
| 47 | * Return: A &struct rtas_work_area descriptor for the allocated work area. |
| 48 | */ |
| 49 | #define rtas_work_area_alloc(size_) ({ \ |
| 50 | static_assert(__builtin_constant_p(size_)); \ |
| 51 | static_assert((size_) > 0); \ |
| 52 | static_assert((size_) <= RTAS_WORK_AREA_MAX_ALLOC_SZ); \ |
| 53 | __rtas_work_area_alloc(size_); \ |
| 54 | }) |
| 55 | |
| 56 | /* |
| 57 | * Do not call __rtas_work_area_alloc() directly. Use |
| 58 | * rtas_work_area_alloc(). |
| 59 | */ |
| 60 | struct rtas_work_area *__rtas_work_area_alloc(size_t size); |
| 61 | |
| 62 | /** |
| 63 | * rtas_work_area_free() - Release a work area. |
| 64 | * @area: Work area descriptor as returned from rtas_work_area_alloc(). |
| 65 | * |
| 66 | * Return a work area buffer to the pool. |
| 67 | */ |
| 68 | void rtas_work_area_free(struct rtas_work_area *area); |
| 69 | |
| 70 | static inline char *rtas_work_area_raw_buf(const struct rtas_work_area *area) |
| 71 | { |
| 72 | return area->buf; |
| 73 | } |
| 74 | |
| 75 | static inline size_t rtas_work_area_size(const struct rtas_work_area *area) |
| 76 | { |
| 77 | return area->size; |
| 78 | } |
| 79 | |
| 80 | static inline phys_addr_t rtas_work_area_phys(const struct rtas_work_area *area) |
| 81 | { |
| 82 | return __pa(area->buf); |
| 83 | } |
| 84 | |
| 85 | /* |
| 86 | * Early setup for the work area allocator. Call from |
| 87 | * rtas_initialize() only. |
| 88 | */ |
| 89 | |
| 90 | #ifdef CONFIG_PPC_PSERIES |
| 91 | void rtas_work_area_reserve_arena(phys_addr_t limit); |
| 92 | #else /* CONFIG_PPC_PSERIES */ |
| 93 | static inline void rtas_work_area_reserve_arena(phys_addr_t limit) {} |
| 94 | #endif /* CONFIG_PPC_PSERIES */ |
| 95 | |
| 96 | #endif /* _ASM_POWERPC_RTAS_WORK_AREA_H */ |
| 97 |
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