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936b9df7a5
The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:
struct foo {
int stuff;
struct boo array[];
};
By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.
Also, notice that, dynamic memory allocations won't be affected by
this change:
"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]
sizeof(flexible-array-member) triggers a warning because flexible array
members have incomplete type[1]. There are some instances of code in
which the sizeof operator is being incorrectly/erroneously applied to
zero-length arrays and the result is zero. Such instances may be hiding
some bugs. So, this work (flexible-array member conversions) will also
help to get completely rid of those sorts of issues.
This issue was found with the help of Coccinelle.
[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 7649773293 ("cxgb3/l2t: Fix undefined behaviour")
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Acked-by: Cezary Rojewski <cezary.rojewski@intel.com>
Link: https://lore.kernel.org/r/20200511174647.GA17318@embeddedor
Signed-off-by: Mark Brown <broonie@kernel.org>
87 lines
2.1 KiB
C
87 lines
2.1 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* skl-i2s.h - i2s blob mapping
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*
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* Copyright (C) 2017 Intel Corp
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* Author: Subhransu S. Prusty < subhransu.s.prusty@intel.com>
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* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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*
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* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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*/
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#ifndef __SOUND_SOC_SKL_I2S_H
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#define __SOUND_SOC_SKL_I2S_H
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#define SKL_I2S_MAX_TIME_SLOTS 8
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#define SKL_MCLK_DIV_CLK_SRC_MASK GENMASK(17, 16)
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#define SKL_MNDSS_DIV_CLK_SRC_MASK GENMASK(21, 20)
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#define SKL_SHIFT(x) (ffs(x) - 1)
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#define SKL_MCLK_DIV_RATIO_MASK GENMASK(11, 0)
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#define is_legacy_blob(x) (x.signature != 0xEE)
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#define ext_to_legacy_blob(i2s_config_blob_ext) \
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((struct skl_i2s_config_blob_legacy *) i2s_config_blob_ext)
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#define get_clk_src(mclk, mask) \
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((mclk.mdivctrl & mask) >> SKL_SHIFT(mask))
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struct skl_i2s_config {
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u32 ssc0;
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u32 ssc1;
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u32 sscto;
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u32 sspsp;
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u32 sstsa;
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u32 ssrsa;
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u32 ssc2;
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u32 sspsp2;
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u32 ssc3;
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u32 ssioc;
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} __packed;
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struct skl_i2s_config_mclk {
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u32 mdivctrl;
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u32 mdivr;
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};
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struct skl_i2s_config_mclk_ext {
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u32 mdivctrl;
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u32 mdivr_count;
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u32 mdivr[];
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} __packed;
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struct skl_i2s_config_blob_signature {
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u32 minor_ver : 8;
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u32 major_ver : 8;
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u32 resvdz : 8;
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u32 signature : 8;
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} __packed;
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struct skl_i2s_config_blob_header {
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struct skl_i2s_config_blob_signature sig;
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u32 size;
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};
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/**
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* struct skl_i2s_config_blob_legacy - Structure defines I2S Gateway
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* configuration legacy blob
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*
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* @gtw_attr: Gateway attribute for the I2S Gateway
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* @tdm_ts_group: TDM slot mapping against channels in the Gateway.
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* @i2s_cfg: I2S HW registers
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* @mclk: MCLK clock source and divider values
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*/
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struct skl_i2s_config_blob_legacy {
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u32 gtw_attr;
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u32 tdm_ts_group[SKL_I2S_MAX_TIME_SLOTS];
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struct skl_i2s_config i2s_cfg;
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struct skl_i2s_config_mclk mclk;
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};
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struct skl_i2s_config_blob_ext {
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u32 gtw_attr;
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struct skl_i2s_config_blob_header hdr;
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u32 tdm_ts_group[SKL_I2S_MAX_TIME_SLOTS];
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struct skl_i2s_config i2s_cfg;
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struct skl_i2s_config_mclk_ext mclk;
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} __packed;
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#endif /* __SOUND_SOC_SKL_I2S_H */
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