spi: cs42l43: Add bridged cs35l56 amplifiers

On some cs42l43 systems a couple of cs35l56 amplifiers are attached
to the cs42l43's SPI and I2S. On Windows the cs42l43 is controlled
by a SDCA class driver and these two amplifiers are controlled by
firmware running on the cs42l43. However, under Linux the decision
was made to interact with the cs42l43 directly, affording the user
greater control over the audio system. However, this has resulted
in an issue where these two bridged cs35l56 amplifiers are not
populated in ACPI and must be added manually.

Check for the presence of the "01fa-cirrus-sidecar-instances" property
in the SDCA extension unit's ACPI properties to confirm the presence
of these two amplifiers and if they exist add them manually onto the
SPI bus.
Reviewed-by: Andy Shevchenko <andy@kernel.org>
Signed-off-by: Maciej Strozek <mstrozek@opensource.cirrus.com>
Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Link: https://lore.kernel.org/r/20240416100904.3738093-5-ckeepax@opensource.cirrus.comSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/Kconfig

@@ -284,6 +284,7 @@ config SPI_COLDFIRE_QSPI
 config SPI_CS42L43
 	tristate "Cirrus Logic CS42L43 SPI controller"
 	depends on MFD_CS42L43 && PINCTRL_CS42L43
+	select GPIO_SWNODE_UNDEFINED
 	help
 	  This enables support for the SPI controller inside the Cirrus Logic
 	  CS42L43 audio codec.

drivers/spi/spi-cs42l43.c

@@ -5,10 +5,14 @@
 // Copyright (C) 2022-2023 Cirrus Logic, Inc. and
 //                         Cirrus Logic International Semiconductor Ltd.
 
+#include <linux/acpi.h>
+#include <linux/array_size.h>
 #include <linux/bits.h>
 #include <linux/bitfield.h>
 #include <linux/device.h>
 #include <linux/errno.h>
+#include <linux/gpio/machine.h>
+#include <linux/gpio/property.h>
 #include <linux/mfd/cs42l43.h>
 #include <linux/mfd/cs42l43-regs.h>
 #include <linux/mod_devicetable.h>
@@ -16,6 +20,7 @@
 #include <linux/of.h>
 #include <linux/platform_device.h>
 #include <linux/pm_runtime.h>
+#include <linux/property.h>
 #include <linux/regmap.h>
 #include <linux/spi/spi.h>
 #include <linux/units.h>
@@ -39,6 +44,44 @@ static const unsigned int cs42l43_clock_divs[] = {
 	2, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30
 };
 
+static const struct software_node ampl = {
+	.name			= "cs35l56-left",
+};
+
+static const struct software_node ampr = {
+	.name			= "cs35l56-right",
+};
+
+static struct spi_board_info ampl_info = {
+	.modalias		= "cs35l56",
+	.max_speed_hz		= 20 * HZ_PER_MHZ,
+	.chip_select		= 0,
+	.mode			= SPI_MODE_0,
+	.swnode			= &ampl,
+};
+
+static struct spi_board_info ampr_info = {
+	.modalias		= "cs35l56",
+	.max_speed_hz		= 20 * HZ_PER_MHZ,
+	.chip_select		= 1,
+	.mode			= SPI_MODE_0,
+	.swnode			= &ampr,
+};
+
+static const struct software_node cs42l43_gpiochip_swnode = {
+	.name			= "cs42l43-pinctrl",
+};
+
+static const struct software_node_ref_args cs42l43_cs_refs[] = {
+	SOFTWARE_NODE_REFERENCE(&cs42l43_gpiochip_swnode, 0, GPIO_ACTIVE_LOW),
+	SOFTWARE_NODE_REFERENCE(&swnode_gpio_undefined),
+};
+
+static const struct property_entry cs42l43_cs_props[] = {
+	PROPERTY_ENTRY_REF_ARRAY("cs-gpios", cs42l43_cs_refs),
+	{}
+};
+
 static int cs42l43_spi_tx(struct regmap *regmap, const u8 *buf, unsigned int len)
 {
 	const u8 *end = buf + len;
@@ -203,16 +246,59 @@ static size_t cs42l43_spi_max_length(struct spi_device *spi)
 	return CS42L43_SPI_MAX_LENGTH;
 }
 
+static bool cs42l43_has_sidecar(struct fwnode_handle *fwnode)
+{
+	static const u32 func_smart_amp = 0x1;
+	struct fwnode_handle *child_fwnode, *ext_fwnode;
+	unsigned int val;
+	u32 function;
+	int ret;
+
+	fwnode_for_each_child_node(fwnode, child_fwnode) {
+		acpi_handle handle = ACPI_HANDLE_FWNODE(child_fwnode);
+
+		ret = acpi_get_local_address(handle, &function);
+		if (ret || function != func_smart_amp)
+			continue;
+
+		ext_fwnode = fwnode_get_named_child_node(child_fwnode,
+				"mipi-sdca-function-expansion-subproperties");
+		if (!ext_fwnode)
+			continue;
+
+		ret = fwnode_property_read_u32(ext_fwnode,
+					       "01fa-cirrus-sidecar-instances",
+					       &val);
+
+		fwnode_handle_put(ext_fwnode);
+
+		if (ret)
+			continue;
+
+		fwnode_handle_put(child_fwnode);
+
+		return !!val;
+	}
+
+	return false;
+}
+
 static void cs42l43_release_of_node(void *data)
 {
 	fwnode_handle_put(data);
 }
 
+static void cs42l43_release_sw_node(void *data)
+{
+	software_node_unregister(&cs42l43_gpiochip_swnode);
+}
+
 static int cs42l43_spi_probe(struct platform_device *pdev)
 {
 	struct cs42l43 *cs42l43 = dev_get_drvdata(pdev->dev.parent);
 	struct cs42l43_spi *priv;
 	struct fwnode_handle *fwnode = dev_fwnode(cs42l43->dev);
+	bool has_sidecar = cs42l43_has_sidecar(fwnode);
 	int ret;
 
 	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
@@ -266,14 +352,42 @@ static int cs42l43_spi_probe(struct platform_device *pdev)
 		}
 	}
 
-	device_set_node(&priv->ctlr->dev, fwnode);
+	if (has_sidecar) {
+		ret = software_node_register(&cs42l43_gpiochip_swnode);
+		if (ret)
+			return dev_err_probe(priv->dev, ret,
+					     "Failed to register gpio swnode\n");
+
+		ret = devm_add_action(priv->dev, cs42l43_release_sw_node, NULL);
+		if (ret) {
+			software_node_unregister(&cs42l43_gpiochip_swnode);
+			return ret;
+		}
+
+		ret = device_create_managed_software_node(&priv->ctlr->dev,
+							  cs42l43_cs_props, NULL);
+		if (ret)
+			return dev_err_probe(priv->dev, ret, "Failed to add swnode\n");
+	} else {
+		device_set_node(&priv->ctlr->dev, fwnode);
+	}
 
 	ret = devm_spi_register_controller(priv->dev, priv->ctlr);
-	if (ret) {
-		dev_err(priv->dev, "Failed to register SPI controller: %d\n", ret);
+	if (ret)
+		return dev_err_probe(priv->dev, ret,
+				     "Failed to register SPI controller\n");
+
+	if (has_sidecar) {
+		if (!spi_new_device(priv->ctlr, &ampl_info))
+			return dev_err_probe(priv->dev, -ENODEV,
+					     "Failed to create left amp slave\n");
+
+		if (!spi_new_device(priv->ctlr, &ampr_info))
+			return dev_err_probe(priv->dev, -ENODEV,
+					     "Failed to create right amp slave\n");
 	}
 
-	return ret;
+	return 0;
 }
 
 static const struct platform_device_id cs42l43_spi_id_table[] = {
@@ -291,6 +405,7 @@ static struct platform_driver cs42l43_spi_driver = {
 };
 module_platform_driver(cs42l43_spi_driver);
 
+MODULE_IMPORT_NS(GPIO_SWNODE);
 MODULE_DESCRIPTION("CS42L43 SPI Driver");
 MODULE_AUTHOR("Lucas Tanure <tanureal@opensource.cirrus.com>");
 MODULE_AUTHOR("Maciej Strozek <mstrozek@opensource.cirrus.com>");