ASoC: Intel: bytcht_es8316: Add external speaker mux support

The ES8316 only has a single (amplified) output. The ES8316 appnote showing
the intended usage uses a jack-receptacle which physically disconnects the
speakers from the output when a jack is plugged in.

But all 3 devices using the es8316 which I have (2 Cherry Trail devices and
one Bay Trail CR device), use an analog mux to disconnect the speakers,
driven by a GPIO.

This commit adds support for this, modelling this as a separate speaker
widget / dapm pin-switch which sets the mux to drive the speakers when
selected.

The intend is for userspace to use the recently added jack-detect support
and then automatically select either the Headphone or Speaker output based
on that.

Note this commit includes a workaround for an ACPI table bug which is
present on 2 of the 3 devices I have, see the added comment in the code.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/intel/boards/bytcht_es8316.c

@@ -19,8 +19,11 @@
  *
  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  */
+#include <linux/acpi.h>
 #include <linux/clk.h>
 #include <linux/device.h>
+#include <linux/gpio/consumer.h>
+#include <linux/i2c.h>
 #include <linux/init.h>
 #include <linux/input.h>
 #include <linux/module.h>
@@ -40,6 +43,8 @@
 struct byt_cht_es8316_private {
 	struct clk *mclk;
 	struct snd_soc_jack jack;
+	struct gpio_desc *speaker_en_gpio;
+	bool speaker_en;
 };
 
 #define BYT_CHT_ES8316_SSP0			BIT(16)
@@ -56,7 +61,24 @@ static void log_quirks(struct device *dev)
 		dev_info(dev, "quirk SSP0 enabled");
 }
 
+static int byt_cht_es8316_speaker_power_event(struct snd_soc_dapm_widget *w,
+	struct snd_kcontrol *kcontrol, int event)
+{
+	struct snd_soc_card *card = w->dapm->card;
+	struct byt_cht_es8316_private *priv = snd_soc_card_get_drvdata(card);
+
+	if (SND_SOC_DAPM_EVENT_ON(event))
+		priv->speaker_en = true;
+	else
+		priv->speaker_en = false;
+
+	gpiod_set_value_cansleep(priv->speaker_en_gpio, priv->speaker_en);
+
+	return 0;
+}
+
 static const struct snd_soc_dapm_widget byt_cht_es8316_widgets[] = {
+	SND_SOC_DAPM_SPK("Speaker", NULL),
 	SND_SOC_DAPM_HP("Headphone", NULL),
 	SND_SOC_DAPM_MIC("Headset Mic", NULL),
 
@@ -67,6 +89,10 @@ static const struct snd_soc_dapm_widget byt_cht_es8316_widgets[] = {
 	 */
 	SND_SOC_DAPM_MIC("Microphone 1", NULL),
 	SND_SOC_DAPM_MIC("Microphone 2", NULL),
+
+	SND_SOC_DAPM_SUPPLY("Speaker Power", SND_SOC_NOPM, 0, 0,
+			    byt_cht_es8316_speaker_power_event,
+			    SND_SOC_DAPM_PRE_PMD | SND_SOC_DAPM_POST_PMU),
 };
 
 static const struct snd_soc_dapm_route byt_cht_es8316_audio_map[] = {
@@ -76,6 +102,14 @@ static const struct snd_soc_dapm_route byt_cht_es8316_audio_map[] = {
 
 	{"Headphone", NULL, "HPOL"},
 	{"Headphone", NULL, "HPOR"},
+
+	/*
+	 * There is no separate speaker output instead the speakers are muxed to
+	 * the HP outputs. The mux is controlled by the "Speaker Power" supply.
+	 */
+	{"Speaker", NULL, "HPOL"},
+	{"Speaker", NULL, "HPOR"},
+	{"Speaker", NULL, "Speaker Power"},
 };
 
 static const struct snd_soc_dapm_route byt_cht_es8316_ssp0_map[] = {
@@ -95,6 +129,7 @@ static const struct snd_soc_dapm_route byt_cht_es8316_ssp2_map[] = {
 };
 
 static const struct snd_kcontrol_new byt_cht_es8316_controls[] = {
+	SOC_DAPM_PIN_SWITCH("Speaker"),
 	SOC_DAPM_PIN_SWITCH("Headphone"),
 	SOC_DAPM_PIN_SWITCH("Headset Mic"),
 	SOC_DAPM_PIN_SWITCH("Microphone 1"),
@@ -323,6 +358,25 @@ static int byt_cht_es8316_resume(struct snd_soc_card *card)
 		}
 	}
 
+	/*
+	 * Some Cherry Trail boards with an ES8316 codec have a bug in their
+	 * ACPI tables where the MSSL1680 touchscreen's _PS0 and _PS3 methods
+	 * wrongly also set the speaker-enable GPIO to 1/0. Testing has shown
+	 * that this really is a bug and the GPIO has no influence on the
+	 * touchscreen at all.
+	 *
+	 * The silead.c touchscreen driver does not support runtime suspend, so
+	 * the GPIO can only be changed underneath us during a system suspend.
+	 * This resume() function runs from a pm complete() callback, and thus
+	 * is guaranteed to run after the touchscreen driver/ACPI-subsys has
+	 * brought the touchscreen back up again (and thus changed the GPIO).
+	 *
+	 * So to work around this we pass GPIOD_FLAGS_BIT_NONEXCLUSIVE when
+	 * requesting the GPIO and we set its value here to undo any changes
+	 * done by the touchscreen's broken _PS0 ACPI method.
+	 */
+	gpiod_set_value_cansleep(priv->speaker_en_gpio, priv->speaker_en);
+
 	return 0;
 }
 
@@ -347,12 +401,20 @@ static const struct x86_cpu_id baytrail_cpu_ids[] = {
 	{}
 };
 
+static const struct acpi_gpio_params first_gpio = { 0, 0, false };
+
+static const struct acpi_gpio_mapping byt_cht_es8316_gpios[] = {
+	{ "speaker-enable-gpios", &first_gpio, 1 },
+	{ },
+};
+
 static int snd_byt_cht_es8316_mc_probe(struct platform_device *pdev)
 {
 	struct byt_cht_es8316_private *priv;
 	struct device *dev = &pdev->dev;
 	struct snd_soc_acpi_mach *mach;
 	const char *i2c_name = NULL;
+	struct device *codec_dev;
 	int dai_index = 0;
 	int i;
 	int ret = 0;
@@ -405,12 +467,39 @@ static int snd_byt_cht_es8316_mc_probe(struct platform_device *pdev)
 		return ret;
 	}
 
+	/* get speaker enable GPIO */
+	codec_dev = bus_find_device_by_name(&i2c_bus_type, NULL, codec_name);
+	if (!codec_dev)
+		return -EPROBE_DEFER;
+
+	devm_acpi_dev_add_driver_gpios(codec_dev, byt_cht_es8316_gpios);
+	priv->speaker_en_gpio =
+		gpiod_get_index(codec_dev, "speaker-enable", 0,
+				/* see comment in byt_cht_es8316_resume */
+				GPIOD_OUT_LOW | GPIOD_FLAGS_BIT_NONEXCLUSIVE);
+	put_device(codec_dev);
+
+	if (IS_ERR(priv->speaker_en_gpio)) {
+		ret = PTR_ERR(priv->speaker_en_gpio);
+		switch (ret) {
+		case -ENOENT:
+			priv->speaker_en_gpio = NULL;
+			break;
+		default:
+			dev_err(dev, "get speaker GPIO failed: %d\n", ret);
+			/* fall through */
+		case -EPROBE_DEFER:
+			return ret;
+		}
+	}
+
 	/* register the soc card */
 	byt_cht_es8316_card.dev = dev;
 	snd_soc_card_set_drvdata(&byt_cht_es8316_card, priv);
 
 	ret = devm_snd_soc_register_card(dev, &byt_cht_es8316_card);
 	if (ret) {
+		gpiod_put(priv->speaker_en_gpio);
 		dev_err(dev, "snd_soc_register_card failed: %d\n", ret);
 		return ret;
 	}
@@ -418,11 +507,20 @@ static int snd_byt_cht_es8316_mc_probe(struct platform_device *pdev)
 	return 0;
 }
 
+static int snd_byt_cht_es8316_mc_remove(struct platform_device *pdev)
+{
+	struct byt_cht_es8316_private *priv = platform_get_drvdata(pdev);
+
+	gpiod_put(priv->speaker_en_gpio);
+	return 0;
+}
+
 static struct platform_driver snd_byt_cht_es8316_mc_driver = {
 	.driver = {
 		.name = "bytcht_es8316",
 	},
 	.probe = snd_byt_cht_es8316_mc_probe,
+	.remove = snd_byt_cht_es8316_mc_remove,
 };
 
 module_platform_driver(snd_byt_cht_es8316_mc_driver);