83d290c56f
When U-Boot started using SPDX tags we were among the early adopters and there weren't a lot of other examples to borrow from. So we picked the area of the file that usually had a full license text and replaced it with an appropriate SPDX-License-Identifier: entry. Since then, the Linux Kernel has adopted SPDX tags and they place it as the very first line in a file (except where shebangs are used, then it's second line) and with slightly different comment styles than us. In part due to community overlap, in part due to better tag visibility and in part for other minor reasons, switch over to that style. This commit changes all instances where we have a single declared license in the tag as both the before and after are identical in tag contents. There's also a few places where I found we did not have a tag and have introduced one. Signed-off-by: Tom Rini <trini@konsulko.com>
90 lines
2.5 KiB
C
90 lines
2.5 KiB
C
/* SPDX-License-Identifier: GPL-2.0+ */
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/*
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* Copyright 2013 Broadcom Corporation.
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*/
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/*
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* Bitfield operations
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*
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* These are generic bitfield operations which allow manipulation of variable
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* width bitfields within a word. One use of this would be to use data tables
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* to determine how to reprogram fields within R/W hardware registers.
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*
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* Example:
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*
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* old_reg_val
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* +--------+----+---+--+-----+----------+
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* | | | | | old | |
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* +--------+----+---+--+-----+----------+
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*
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* new_reg_val
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* +--------+----+---+--+-----+----------+
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* | | | | | new | |
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* +--------+----+---+--+-----+----------+
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*
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* mask = bitfield_mask(10, 5);
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* old = bitfield_extract(old_reg_val, 10, 5);
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* new_reg_val = bitfield_replace(old_reg_val, 10, 5, new);
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*
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* or
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*
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* mask = bitfield_mask(10, 5);
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* old = bitfield_extract_by_mask(old_reg_val, mask);
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* new_reg_val = bitfield_replace_by_mask(old_reg_val, mask, new);
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*
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* The numbers 10 and 5 could for example come from data
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* tables which describe all bitfields in all registers.
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*/
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#include <linux/types.h>
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/* Produces a mask of set bits covering a range of a uint value */
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static inline uint bitfield_mask(uint shift, uint width)
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{
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return ((1 << width) - 1) << shift;
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}
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/* Extract the value of a bitfield found within a given register value */
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static inline uint bitfield_extract(uint reg_val, uint shift, uint width)
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{
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return (reg_val & bitfield_mask(shift, width)) >> shift;
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}
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/*
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* Replace the value of a bitfield found within a given register value
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* Returns the newly modified uint value with the replaced field.
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*/
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static inline uint bitfield_replace(uint reg_val, uint shift, uint width,
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uint bitfield_val)
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{
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uint mask = bitfield_mask(shift, width);
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return (reg_val & ~mask) | ((bitfield_val << shift) & mask);
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}
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/* Produces a shift of the bitfield given a mask */
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static inline uint bitfield_shift(uint mask)
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{
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return mask ? ffs(mask) - 1 : 0;
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}
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/* Extract the value of a bitfield found within a given register value */
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static inline uint bitfield_extract_by_mask(uint reg_val, uint mask)
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{
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uint shift = bitfield_shift(mask);
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return (reg_val & mask) >> shift;
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}
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/*
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* Replace the value of a bitfield found within a given register value
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* Returns the newly modified uint value with the replaced field.
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*/
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static inline uint bitfield_replace_by_mask(uint reg_val, uint mask,
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uint bitfield_val)
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{
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uint shift = bitfield_shift(mask);
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return (reg_val & ~mask) | ((bitfield_val << shift) & mask);
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}
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