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5979afa2c4
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]
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 <gustavo@embeddedor.com>
Link: https://lore.kernel.org/r/20200220132908.GA30501@embeddedor
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
133 lines
4.1 KiB
C
133 lines
4.1 KiB
C
/* SPDX-License-Identifier: BSD-3-Clause */
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/*
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* Copyright (c) 2015-2016 Google Inc.
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*/
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/*
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* This is a special protocol for configuring communication over the
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* I2S bus between the DSP on the MSM8994 and APBridgeA. Therefore,
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* we can predefine several low-level attributes of the communication
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* because we know that they are supported. In particular, the following
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* assumptions are made:
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* - there are two channels (i.e., stereo)
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* - the low-level protocol is I2S as defined by Philips/NXP
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* - the DSP on the MSM8994 is the clock master for MCLK, BCLK, and WCLK
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* - WCLK changes on the falling edge of BCLK
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* - WCLK low for left channel; high for right channel
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* - TX data is sent on the falling edge of BCLK
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* - RX data is received/latched on the rising edge of BCLK
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*/
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#ifndef __AUDIO_APBRIDGEA_H
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#define __AUDIO_APBRIDGEA_H
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#define AUDIO_APBRIDGEA_TYPE_SET_CONFIG 0x01
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#define AUDIO_APBRIDGEA_TYPE_REGISTER_CPORT 0x02
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#define AUDIO_APBRIDGEA_TYPE_UNREGISTER_CPORT 0x03
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#define AUDIO_APBRIDGEA_TYPE_SET_TX_DATA_SIZE 0x04
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/* 0x05 unused */
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#define AUDIO_APBRIDGEA_TYPE_PREPARE_TX 0x06
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#define AUDIO_APBRIDGEA_TYPE_START_TX 0x07
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#define AUDIO_APBRIDGEA_TYPE_STOP_TX 0x08
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#define AUDIO_APBRIDGEA_TYPE_SHUTDOWN_TX 0x09
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#define AUDIO_APBRIDGEA_TYPE_SET_RX_DATA_SIZE 0x0a
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/* 0x0b unused */
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#define AUDIO_APBRIDGEA_TYPE_PREPARE_RX 0x0c
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#define AUDIO_APBRIDGEA_TYPE_START_RX 0x0d
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#define AUDIO_APBRIDGEA_TYPE_STOP_RX 0x0e
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#define AUDIO_APBRIDGEA_TYPE_SHUTDOWN_RX 0x0f
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#define AUDIO_APBRIDGEA_PCM_FMT_8 BIT(0)
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#define AUDIO_APBRIDGEA_PCM_FMT_16 BIT(1)
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#define AUDIO_APBRIDGEA_PCM_FMT_24 BIT(2)
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#define AUDIO_APBRIDGEA_PCM_FMT_32 BIT(3)
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#define AUDIO_APBRIDGEA_PCM_FMT_64 BIT(4)
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#define AUDIO_APBRIDGEA_PCM_RATE_5512 BIT(0)
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#define AUDIO_APBRIDGEA_PCM_RATE_8000 BIT(1)
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#define AUDIO_APBRIDGEA_PCM_RATE_11025 BIT(2)
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#define AUDIO_APBRIDGEA_PCM_RATE_16000 BIT(3)
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#define AUDIO_APBRIDGEA_PCM_RATE_22050 BIT(4)
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#define AUDIO_APBRIDGEA_PCM_RATE_32000 BIT(5)
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#define AUDIO_APBRIDGEA_PCM_RATE_44100 BIT(6)
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#define AUDIO_APBRIDGEA_PCM_RATE_48000 BIT(7)
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#define AUDIO_APBRIDGEA_PCM_RATE_64000 BIT(8)
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#define AUDIO_APBRIDGEA_PCM_RATE_88200 BIT(9)
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#define AUDIO_APBRIDGEA_PCM_RATE_96000 BIT(10)
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#define AUDIO_APBRIDGEA_PCM_RATE_176400 BIT(11)
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#define AUDIO_APBRIDGEA_PCM_RATE_192000 BIT(12)
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#define AUDIO_APBRIDGEA_DIRECTION_TX BIT(0)
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#define AUDIO_APBRIDGEA_DIRECTION_RX BIT(1)
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/* The I2S port is passed in the 'index' parameter of the USB request */
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/* The CPort is passed in the 'value' parameter of the USB request */
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struct audio_apbridgea_hdr {
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__u8 type;
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__le16 i2s_port;
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__u8 data[];
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} __packed;
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struct audio_apbridgea_set_config_request {
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struct audio_apbridgea_hdr hdr;
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__le32 format; /* AUDIO_APBRIDGEA_PCM_FMT_* */
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__le32 rate; /* AUDIO_APBRIDGEA_PCM_RATE_* */
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__le32 mclk_freq; /* XXX Remove? */
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} __packed;
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struct audio_apbridgea_register_cport_request {
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struct audio_apbridgea_hdr hdr;
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__le16 cport;
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__u8 direction;
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} __packed;
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struct audio_apbridgea_unregister_cport_request {
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struct audio_apbridgea_hdr hdr;
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__le16 cport;
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__u8 direction;
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} __packed;
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struct audio_apbridgea_set_tx_data_size_request {
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struct audio_apbridgea_hdr hdr;
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__le16 size;
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} __packed;
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struct audio_apbridgea_prepare_tx_request {
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struct audio_apbridgea_hdr hdr;
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} __packed;
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struct audio_apbridgea_start_tx_request {
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struct audio_apbridgea_hdr hdr;
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__le64 timestamp;
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} __packed;
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struct audio_apbridgea_stop_tx_request {
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struct audio_apbridgea_hdr hdr;
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} __packed;
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struct audio_apbridgea_shutdown_tx_request {
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struct audio_apbridgea_hdr hdr;
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} __packed;
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struct audio_apbridgea_set_rx_data_size_request {
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struct audio_apbridgea_hdr hdr;
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__le16 size;
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} __packed;
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struct audio_apbridgea_prepare_rx_request {
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struct audio_apbridgea_hdr hdr;
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} __packed;
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struct audio_apbridgea_start_rx_request {
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struct audio_apbridgea_hdr hdr;
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} __packed;
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struct audio_apbridgea_stop_rx_request {
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struct audio_apbridgea_hdr hdr;
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} __packed;
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struct audio_apbridgea_shutdown_rx_request {
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struct audio_apbridgea_hdr hdr;
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} __packed;
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#endif /*__AUDIO_APBRIDGEA_H */
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