ASoC: ssm2305: Add amplifier driver

The ssm2305 is a simple Class-D audio amplifier. A application can
turn on/off the device by a gpio. It's also possible to hardwire the
shutdown pin.

Tested on a i.MX6 based custom board.
Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
Reviewed-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/sound/adi,ssm2305.txt

+Analog Devices SSM2305 Speaker Amplifier
+========================================
+
+Required properties:
+  - compatible : "adi,ssm2305"
+  - shutdown-gpios : The gpio connected to the shutdown pin.
+                     The gpio signal is ACTIVE_LOW.
+
+Example:
+
+ssm2305: analog-amplifier {
+	compatible = "adi,ssm2305";
+	shutdown-gpios = <&gpio3 20 GPIO_ACTIVE_LOW>;
+};

sound/soc/codecs/Kconfig

@@ -145,6 +145,7 @@ config SND_SOC_ALL_CODECS
 	select SND_SOC_SI476X if MFD_SI476X_CORE
 	select SND_SOC_SIRF_AUDIO_CODEC
 	select SND_SOC_SPDIF
+	select SND_SOC_SSM2305
 	select SND_SOC_SSM2518 if I2C
 	select SND_SOC_SSM2602_SPI if SPI_MASTER
 	select SND_SOC_SSM2602_I2C if I2C
@@ -896,6 +897,12 @@ config SND_SOC_SIRF_AUDIO_CODEC
 config SND_SOC_SPDIF
 	tristate "S/PDIF CODEC"
 
+config SND_SOC_SSM2305
+	tristate "Analog Devices SSM2305 Class-D Amplifier"
+	help
+	  Enable support for Analog Devices SSM2305 filterless
+	  high-efficiency mono Class-D audio power amplifiers.
+
 config SND_SOC_SSM2518
 	tristate
 

sound/soc/codecs/Makefile

@@ -156,6 +156,7 @@ snd-soc-si476x-objs := si476x.o
 snd-soc-sirf-audio-codec-objs := sirf-audio-codec.o
 snd-soc-spdif-tx-objs := spdif_transmitter.o
 snd-soc-spdif-rx-objs := spdif_receiver.o
+snd-soc-ssm2305-objs := ssm2305.o
 snd-soc-ssm2518-objs := ssm2518.o
 snd-soc-ssm2602-objs := ssm2602.o
 snd-soc-ssm2602-spi-objs := ssm2602-spi.o
@@ -410,6 +411,7 @@ obj-$(CONFIG_SND_SOC_SIGMADSP_REGMAP)	+= snd-soc-sigmadsp-regmap.o
 obj-$(CONFIG_SND_SOC_SI476X)	+= snd-soc-si476x.o
 obj-$(CONFIG_SND_SOC_SPDIF)	+= snd-soc-spdif-rx.o snd-soc-spdif-tx.o
 obj-$(CONFIG_SND_SOC_SIRF_AUDIO_CODEC) += sirf-audio-codec.o
+obj-$(CONFIG_SND_SOC_SSM2305)	+= snd-soc-ssm2305.o
 obj-$(CONFIG_SND_SOC_SSM2518)	+= snd-soc-ssm2518.o
 obj-$(CONFIG_SND_SOC_SSM2602)	+= snd-soc-ssm2602.o
 obj-$(CONFIG_SND_SOC_SSM2602_SPI)	+= snd-soc-ssm2602-spi.o

sound/soc/codecs/ssm2305.c

+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Analog Devices SSM2305 Amplifier Driver
+ *
+ * Copyright (C) 2018 Pengutronix, Marco Felsch <kernel@pengutronix.de>
+ */
+
+#include <linux/gpio/consumer.h>
+#include <linux/module.h>
+#include <sound/soc.h>
+
+#define DRV_NAME "ssm2305"
+
+struct ssm2305 {
+	/* shutdown gpio  */
+	struct gpio_desc *gpiod_shutdown;
+};
+
+static int ssm2305_power_event(struct snd_soc_dapm_widget *w,
+			       struct snd_kcontrol *kctrl, int event)
+{
+	struct snd_soc_component *c = snd_soc_dapm_to_component(w->dapm);
+	struct ssm2305 *data = snd_soc_component_get_drvdata(c);
+
+	gpiod_set_value_cansleep(data->gpiod_shutdown,
+				 SND_SOC_DAPM_EVENT_ON(event));
+
+	return 0;
+}
+
+static const struct snd_soc_dapm_widget ssm2305_dapm_widgets[] = {
+	/* Stereo input/output */
+	SND_SOC_DAPM_INPUT("L_IN"),
+	SND_SOC_DAPM_INPUT("R_IN"),
+	SND_SOC_DAPM_OUTPUT("L_OUT"),
+	SND_SOC_DAPM_OUTPUT("R_OUT"),
+
+	SND_SOC_DAPM_SUPPLY("Power", SND_SOC_NOPM, 0, 0, ssm2305_power_event,
+			    SND_SOC_DAPM_PRE_PMU | SND_SOC_DAPM_POST_PMD),
+};
+
+static const struct snd_soc_dapm_route ssm2305_dapm_routes[] = {
+	{ "L_OUT", NULL, "L_IN" },
+	{ "R_OUT", NULL, "R_IN" },
+	{ "L_IN", NULL, "Power" },
+	{ "R_IN", NULL, "Power" },
+};
+
+static const struct snd_soc_component_driver ssm2305_component_driver = {
+	.dapm_widgets		= ssm2305_dapm_widgets,
+	.num_dapm_widgets	= ARRAY_SIZE(ssm2305_dapm_widgets),
+	.dapm_routes		= ssm2305_dapm_routes,
+	.num_dapm_routes	= ARRAY_SIZE(ssm2305_dapm_routes),
+};
+
+static int ssm2305_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct ssm2305 *priv;
+	int err;
+
+	/* Allocate the private data */
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, priv);
+
+	/* Get shutdown gpio */
+	priv->gpiod_shutdown = devm_gpiod_get(dev, "shutdown",
+					      GPIOD_OUT_LOW);
+	if (IS_ERR(priv->gpiod_shutdown)) {
+		err = PTR_ERR(priv->gpiod_shutdown);
+		if (err != -EPROBE_DEFER)
+			dev_err(dev, "Failed to get 'shutdown' gpio: %d\n",
+				err);
+		return err;
+	}
+
+	return devm_snd_soc_register_component(dev, &ssm2305_component_driver,
+					       NULL, 0);
+}
+
+#ifdef CONFIG_OF
+static const struct of_device_id ssm2305_of_match[] = {
+	{ .compatible = "adi,ssm2305", },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, ssm2305_of_match);
+#endif
+
+static struct platform_driver ssm2305_driver = {
+	.driver = {
+		.name = DRV_NAME,
+		.of_match_table = of_match_ptr(ssm2305_of_match),
+	},
+	.probe = ssm2305_probe,
+};
+
+module_platform_driver(ssm2305_driver);
+
+MODULE_DESCRIPTION("ASoC SSM2305 amplifier driver");
+MODULE_AUTHOR("Marco Felsch <m.felsch@pengutronix.de>");
+MODULE_LICENSE("GPL v2");