ASoC: cs35l56: Add basic system suspend handling

This adds the main handling for system suspend but does not handle
re-patching the firmware after system resume.

This is a multi-stage suspend and resume because if there is a
RESET line it is almost certain that it will be shared by all the
amps. So every amp must have done its suspend before we can
assert RESET. Likewise we must de-assert RESET before the amps
can resume.

It's preferable to assert RESET before we turning off regulators, and
while they power up.

The actual suspend and resume is done by using the pair
pm_runtime_force_suspend() and pm_runtime_force_resume() to
re-use our runtime suspend/resume sequences.

pm_runtime_force_suspend() will disable our pm_runtime. If we were
runtime-resumed it calls our runtime_suspend().

pm_runtime_force_resume() re-enables pm_runtime and if we were
originally runtime-resumed before the pm_runtime_force_suspend()
it calls our runtime_resume(). Otherwise it leaves us
runtime-suspended.

The general process is therefore:

 suspend() -> finish dsp_work and then run our runtime_suspend
 suspend_late() -> assert RESET and turn off supplies
 resume_early() -> enable supplies and de-assert RESET
 resume() -> pm_runtime_force_resume()

In addition, to prevent the IRQ handler running in the period
between pm_runtime_force_suspend() and pm_runtime_force_resume()
the parent IRQ is temporarily disabled:
 - from suspend until suspend_noirq
 - from resume_noirq until resume

Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Link: https://lore.kernel.org/r/20230411152528.329803-6-rf@opensource.cirrus.com
Signed-off-by: Mark Brown <broonie@kernel.org>

1 files changed, 26 insertions, 0 deletions

diff --git a/sound/soc/codecs/cs35l56-sdw.c b/sound/soc/codecs/cs35l56-sdw.c
index 448ef3609f4c..947d4e5f4dc9 100644
--- a/sound/soc/codecs/cs35l56-sdw.c
+++ b/sound/soc/codecs/cs35l56-sdw.c
@@ -450,6 +450,29 @@ static int __maybe_unused cs35l56_sdw_runtime_resume(struct device *dev)
 	return 0;
 }
 
+static int __maybe_unused cs35l56_sdw_system_suspend(struct device *dev)
+{
+	struct cs35l56_private *cs35l56 = dev_get_drvdata(dev);
+
+	if (!cs35l56->init_done)
+		return 0;
+
+	/*
+	 * Disable SoundWire interrupts.
+	 * Flush - don't cancel because that could leave an unbalanced pm_runtime_get.
+	 */
+	cs35l56->sdw_irq_no_unmask = true;
+	flush_work(&cs35l56->sdw_irq_work);
+
+	/* Mask interrupts and flush in case sdw_irq_work was queued again */
+	sdw_write_no_pm(cs35l56->sdw_peripheral, CS35L56_SDW_GEN_INT_MASK_1, 0);
+	sdw_read_no_pm(cs35l56->sdw_peripheral, CS35L56_SDW_GEN_INT_STAT_1);
+	sdw_write_no_pm(cs35l56->sdw_peripheral, CS35L56_SDW_GEN_INT_STAT_1, 0xFF);
+	flush_work(&cs35l56->sdw_irq_work);
+
+	return cs35l56_system_suspend(dev);
+}
+
 static int cs35l56_sdw_probe(struct sdw_slave *peripheral, const struct sdw_device_id *id)
 {
 	struct device *dev = &peripheral->dev;
@@ -499,6 +522,9 @@ static int cs35l56_sdw_remove(struct sdw_slave *peripheral)
 
 static const struct dev_pm_ops cs35l56_sdw_pm = {
 	SET_RUNTIME_PM_OPS(cs35l56_sdw_runtime_suspend, cs35l56_sdw_runtime_resume, NULL)
+	SYSTEM_SLEEP_PM_OPS(cs35l56_sdw_system_suspend, cs35l56_system_resume)
+	LATE_SYSTEM_SLEEP_PM_OPS(cs35l56_system_suspend_late, cs35l56_system_resume_early)
+	/* NOIRQ stage not needed, SoundWire doesn't use a hard IRQ */
 };
 
 static const struct sdw_device_id cs35l56_sdw_id[] = {