ASoC: codec: pcm1681: Add optional SCK clock and runtime PM support

The PCM1681 requires its SCK system clock to be running before register
access. On platforms where SCK is provided by a gateable clock, register
access may fail when the clock is disabled.
 
Add support for an optional "sck" clock and enable it before accessing the
device. After enabling SCK, wait for the required 65536 system clock cycles
to allow the device to complete its internal reset sequence.
 
Use runtime PM to manage SCK instead of keeping it enabled for the lifetime
of the device. Disable the clock during runtime suspend and restore it on
runtime resume. Use autosuspend to avoid unnecessary clock toggling between
closely spaced accesses.
 
Since the device register state may be lost when SCK is disabled, enable
the regmap cache. Switch regmap to cache-only mode and mark the cache
dirty on runtime suspend, then synchronize the cached register state after
SCK is restored on runtime resume. Mark the zero-detect status register
volatile since it is updated by hardware.
 
Drop idle_bias_on so that the component can reach SND_SOC_BIAS_OFF and
runtime suspend can gate SCK.

Assisted-by: LLM
Signed-off-by: Mohammad Rafi Shaik <mohammad.rafi.shaik@oss.qualcomm.com>
Reviewed-by: Shawn Guo <shengchao.guo@oss.qualcomm.com>
Link: https://patch.msgid.link/20261009-nord-asoc-driver-support-v3-v3-2-0c1897f21ccf@oss.qualcomm.com
Signed-off-by: Mark Brown <broonie@kernel.org>

0 files changed, 0 insertions, 0 deletions