ASoC: rt5677: Fix build error without CONFIG_SPI

If CONFIG_SPI is n, SND_SOC_RT5677_SPI also is n, building fails:

sound/soc/codecs/rt5677.o: In function `rt5677_irq':
rt5677.c:(.text+0x2dbf): undefined reference to `rt5677_spi_hotword_detected'
sound/soc/codecs/rt5677.o: In function `rt5677_dsp_work':
rt5677.c:(.text+0x3709): undefined reference to `rt5677_spi_write'

This adds stub helpers to fix this.

Reported-by: Hulk Robot <hulkci@huawei.com>
Fixes: 461c623270e4 ("ASoC: rt5677: Load firmware via SPI using delayed work")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Link: https://lore.kernel.org/r/20191127082145.6100-1-yuehaibing@huawei.com
Signed-off-by: Mark Brown <broonie@kernel.org>

ASoC: rt5677: Add a PCM device for streaming hotword via SPI

This patch implements a PCM interface for streaming hotword
phrases over SPI. Userspace can open the PCM device at anytime.
The stream is blocked when no hotword is detected. The mic
audio buffer on the DSP is a ~128KByte ring buffer that holds
~4sec of audio samples recorded from the DMIC (S16_LE, mono,
16KHz). After a hotword is detected, previous 2 seconds of audio
(containing the detected hotword) is streamed first, then live
capture continues until userspace closes the PCM stream.

When transferring, copy one period at a time then call
snd_pcm_period_elapsed(). This reduces the latency of transferring
the initial ~2sec of audio after hotword detect since audio samples
are available for userspace earlier.

Signed-off-by: Ben Zhang <benzh@chromium.org>
Signed-off-by: Curtis Malainey <cujomalainey@chromium.org>
Link: https://lore.kernel.org/r/20191018200449.141123-2-cujomalainey@chromium.org
Signed-off-by: Mark Brown <broonie@kernel.org>

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500

Based on 2 normalized pattern(s):

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation #

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-only

has been chosen to replace the boilerplate/reference in 4122 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Enrico Weigelt <info@metux.net>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190604081206.933168790@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

ASoC: rt5677: Allow arbitrary block read/write via SPI

Added rt5677_spi_read() and refactored rt5677_spi_write() so that
an arbitrary block in the DSP address space can be read/written
via SPI. For example, this allows us to load an ELF DSP firmware
with sparse sections, and stream audio samples from DSP ring buffer.

Signed-off-by: Ben Zhang <benzh@chromium.org>
Acked-by: Oder Chiou <oder_chiou@realtek.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

ASoC: rt5677: Minor coding style and typo fix

Minor coding style and typo fix

Signed-off-by: Oder Chiou <oder_chiou@realtek.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

ASoC: rt5677: Support DSP function for VAD application

The ALC5677 has a programmable DSP, and there is a SPI that is dadicated for DSP
firmware loading. Therefore, the patch includes a SPI driver for writing the DSP
firmware. The VAD(Voice Activaty Detection) has be implemented and use the DSP to
recognize the key phase.

Signed-off-by: Oder Chiou <oder_chiou@realtek.com>
Signed-off-by: Mark Brown <broonie@kernel.org>