ASoC: codecs: wsa881x: add runtime pm support

WSA SoundWire Controller does not support Clock stop and performs a soft reset
on suspend  resume path. Its recommended that WSA881x codecs connected to this
are also reset using a hard reset during suspend resume.

So this codec driver performs a hard reset during suspend resume cycle.
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20220228144235.24208-1-srinivas.kandagatla@linaro.orgSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/codecs/wsa881x.c

@@ -11,6 +11,7 @@
 #include <linux/of_gpio.h>
 #include <linux/regmap.h>
 #include <linux/slab.h>
+#include <linux/pm_runtime.h>
 #include <linux/soundwire/sdw.h>
 #include <linux/soundwire/sdw_registers.h>
 #include <linux/soundwire/sdw_type.h>
@@ -198,6 +199,7 @@
 #define WSA881X_OCP_CTL_TIMER_SEC 2
 #define WSA881X_OCP_CTL_TEMP_CELSIUS 25
 #define WSA881X_OCP_CTL_POLL_TIMER_SEC 60
+#define WSA881X_PROBE_TIMEOUT 1000
 
 #define WSA881X_PA_GAIN_TLV(xname, reg, shift, max, invert, tlv_array) \
 {	.iface = SNDRV_CTL_ELEM_IFACE_MIXER, .name = xname, \
@@ -747,6 +749,12 @@ static int wsa881x_put_pa_gain(struct snd_kcontrol *kc,
 	unsigned int mask = (1 << fls(max)) - 1;
 	int val, ret, min_gain, max_gain;
 
+	ret = pm_runtime_get_sync(comp->dev);
+	if (ret < 0 && ret != -EACCES) {
+		pm_runtime_put_noidle(comp->dev);
+		return ret;
+	}
+
 	max_gain = (max - ucontrol->value.integer.value[0]) & mask;
 	/*
 	 * Gain has to set incrementally in 4 steps
@@ -773,6 +781,9 @@ static int wsa881x_put_pa_gain(struct snd_kcontrol *kc,
 		usleep_range(1000, 1010);
 	}
 
+	pm_runtime_mark_last_busy(comp->dev);
+	pm_runtime_put_autosuspend(comp->dev);
+
 	return 1;
 }
 
@@ -1101,6 +1112,7 @@ static int wsa881x_probe(struct sdw_slave *pdev,
 			 const struct sdw_device_id *id)
 {
 	struct wsa881x_priv *wsa881x;
+	struct device *dev = &pdev->dev;
 
 	wsa881x = devm_kzalloc(&pdev->dev, sizeof(*wsa881x), GFP_KERNEL);
 	if (!wsa881x)
@@ -1132,12 +1144,52 @@ static int wsa881x_probe(struct sdw_slave *pdev,
 		return PTR_ERR(wsa881x->regmap);
 	}
 
+	pm_runtime_set_autosuspend_delay(dev, 3000);
+	pm_runtime_use_autosuspend(dev);
+	pm_runtime_mark_last_busy(dev);
+	pm_runtime_set_active(dev);
+	pm_runtime_enable(dev);
+
 	return devm_snd_soc_register_component(&pdev->dev,
 					       &wsa881x_component_drv,
 					       wsa881x_dais,
 					       ARRAY_SIZE(wsa881x_dais));
 }
 
+static int __maybe_unused wsa881x_runtime_suspend(struct device *dev)
+{
+	struct regmap *regmap = dev_get_regmap(dev, NULL);
+	struct wsa881x_priv *wsa881x = dev_get_drvdata(dev);
+
+	gpiod_direction_output(wsa881x->sd_n, 0);
+
+	regcache_cache_only(regmap, true);
+	regcache_mark_dirty(regmap);
+
+	return 0;
+}
+
+static int __maybe_unused wsa881x_runtime_resume(struct device *dev)
+{
+	struct sdw_slave *slave = dev_to_sdw_dev(dev);
+	struct regmap *regmap = dev_get_regmap(dev, NULL);
+	struct wsa881x_priv *wsa881x = dev_get_drvdata(dev);
+
+	gpiod_direction_output(wsa881x->sd_n, 1);
+
+	wait_for_completion_timeout(&slave->initialization_complete,
+				    msecs_to_jiffies(WSA881X_PROBE_TIMEOUT));
+
+	regcache_cache_only(regmap, false);
+	regcache_sync(regmap);
+
+	return 0;
+}
+
+static const struct dev_pm_ops wsa881x_pm_ops = {
+	SET_RUNTIME_PM_OPS(wsa881x_runtime_suspend, wsa881x_runtime_resume, NULL)
+};
+
 static const struct sdw_device_id wsa881x_slave_id[] = {
 	SDW_SLAVE_ENTRY(0x0217, 0x2010, 0),
 	SDW_SLAVE_ENTRY(0x0217, 0x2110, 0),
@@ -1151,6 +1203,7 @@ static struct sdw_driver wsa881x_codec_driver = {
 	.id_table = wsa881x_slave_id,
 	.driver = {
 		.name	= "wsa881x-codec",
+		.pm = &wsa881x_pm_ops,
 	}
 };
 module_sdw_driver(wsa881x_codec_driver);