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This provides an unified API for accessing register bit fields regardless of memory layout. The basic unit of data for these API functions is the u64. The process of transforming an u64 from native CPU encoding into the peripheral's encoding is called 'pack', and transforming it from peripheral to native CPU encoding is 'unpack'. Signed-off-by: Vladimir Oltean <olteanv@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
50 lines
1.8 KiB
C
50 lines
1.8 KiB
C
/* SPDX-License-Identifier: BSD-3-Clause
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* Copyright (c) 2016-2018, NXP Semiconductors
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* Copyright (c) 2018-2019, Vladimir Oltean <olteanv@gmail.com>
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*/
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#ifndef _LINUX_PACKING_H
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#define _LINUX_PACKING_H
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#include <linux/types.h>
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#include <linux/bitops.h>
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#define QUIRK_MSB_ON_THE_RIGHT BIT(0)
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#define QUIRK_LITTLE_ENDIAN BIT(1)
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#define QUIRK_LSW32_IS_FIRST BIT(2)
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enum packing_op {
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PACK,
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UNPACK,
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};
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/**
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* packing - Convert numbers (currently u64) between a packed and an unpacked
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* format. Unpacked means laid out in memory in the CPU's native
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* understanding of integers, while packed means anything else that
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* requires translation.
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*
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* @pbuf: Pointer to a buffer holding the packed value.
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* @uval: Pointer to an u64 holding the unpacked value.
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* @startbit: The index (in logical notation, compensated for quirks) where
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* the packed value starts within pbuf. Must be larger than, or
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* equal to, endbit.
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* @endbit: The index (in logical notation, compensated for quirks) where
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* the packed value ends within pbuf. Must be smaller than, or equal
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* to, startbit.
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* @op: If PACK, then uval will be treated as const pointer and copied (packed)
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* into pbuf, between startbit and endbit.
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* If UNPACK, then pbuf will be treated as const pointer and the logical
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* value between startbit and endbit will be copied (unpacked) to uval.
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* @quirks: A bit mask of QUIRK_LITTLE_ENDIAN, QUIRK_LSW32_IS_FIRST and
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* QUIRK_MSB_ON_THE_RIGHT.
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*
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* Return: 0 on success, EINVAL or ERANGE if called incorrectly. Assuming
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* correct usage, return code may be discarded.
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* If op is PACK, pbuf is modified.
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* If op is UNPACK, uval is modified.
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*/
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int packing(void *pbuf, u64 *uval, int startbit, int endbit, size_t pbuflen,
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enum packing_op op, u8 quirks);
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#endif
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