--- /dev/null
+// SPDX-License-Identifier: GPL-2.0-only
+//
+// KUnit test for the Cirrus side-codec library.
+//
+// Copyright (C) 2023 Cirrus Logic, Inc. and
+//                    Cirrus Logic International Semiconductor Ltd.
+
+#include <kunit/test.h>
+#include <linux/gpio/driver.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+
+#include "cirrus_scodec.h"
+
+struct cirrus_scodec_test_gpio {
+       unsigned int pin_state;
+       struct gpio_chip chip;
+};
+
+struct cirrus_scodec_test_priv {
+       struct platform_device amp_pdev;
+       struct platform_device *gpio_pdev;
+       struct cirrus_scodec_test_gpio *gpio_priv;
+};
+
+static int cirrus_scodec_test_gpio_get_direction(struct gpio_chip *chip,
+                                                unsigned int offset)
+{
+       return GPIO_LINE_DIRECTION_IN;
+}
+
+static int cirrus_scodec_test_gpio_direction_in(struct gpio_chip *chip,
+                                               unsigned int offset)
+{
+       return 0;
+}
+
+static int cirrus_scodec_test_gpio_get(struct gpio_chip *chip, unsigned int offset)
+{
+       struct cirrus_scodec_test_gpio *gpio_priv = gpiochip_get_data(chip);
+
+       return !!(gpio_priv->pin_state & BIT(offset));
+}
+
+static int cirrus_scodec_test_gpio_direction_out(struct gpio_chip *chip,
+                                                unsigned int offset, int value)
+{
+       return -EOPNOTSUPP;
+}
+
+static void cirrus_scodec_test_gpio_set(struct gpio_chip *chip, unsigned int offset,
+                                       int value)
+{
+}
+
+static int cirrus_scodec_test_gpio_set_config(struct gpio_chip *gc,
+                                             unsigned int offset,
+                                             unsigned long config)
+{
+       switch (pinconf_to_config_param(config)) {
+       case PIN_CONFIG_OUTPUT:
+       case PIN_CONFIG_OUTPUT_ENABLE:
+               return -EOPNOTSUPP;
+       default:
+               return 0;
+       }
+}
+
+static const struct gpio_chip cirrus_scodec_test_gpio_chip = {
+       .label                  = "cirrus_scodec_test_gpio",
+       .owner                  = THIS_MODULE,
+       .request                = gpiochip_generic_request,
+       .free                   = gpiochip_generic_free,
+       .get_direction          = cirrus_scodec_test_gpio_get_direction,
+       .direction_input        = cirrus_scodec_test_gpio_direction_in,
+       .get                    = cirrus_scodec_test_gpio_get,
+       .direction_output       = cirrus_scodec_test_gpio_direction_out,
+       .set                    = cirrus_scodec_test_gpio_set,
+       .set_config             = cirrus_scodec_test_gpio_set_config,
+       .base                   = -1,
+       .ngpio                  = 32,
+};
+
+static int cirrus_scodec_test_gpio_probe(struct platform_device *pdev)
+{
+       struct cirrus_scodec_test_gpio *gpio_priv;
+       int ret;
+
+       gpio_priv = devm_kzalloc(&pdev->dev, sizeof(*gpio_priv), GFP_KERNEL);
+       if (!gpio_priv)
+               return -ENOMEM;
+
+       /* GPIO core modifies our struct gpio_chip so use a copy */
+       gpio_priv->chip = cirrus_scodec_test_gpio_chip;
+       ret = devm_gpiochip_add_data(&pdev->dev, &gpio_priv->chip, gpio_priv);
+       if (ret)
+               return dev_err_probe(&pdev->dev, ret, "Failed to add gpiochip\n");
+
+       dev_set_drvdata(&pdev->dev, gpio_priv);
+
+       return 0;
+}
+
+static struct platform_driver cirrus_scodec_test_gpio_driver = {
+       .driver.name    = "cirrus_scodec_test_gpio_drv",
+       .probe          = cirrus_scodec_test_gpio_probe,
+};
+
+/* software_node referencing the gpio driver */
+static const struct software_node cirrus_scodec_test_gpio_swnode = {
+       .name = "cirrus_scodec_test_gpio",
+};
+
+static int cirrus_scodec_test_create_gpio(struct kunit *test)
+{
+       struct cirrus_scodec_test_priv *priv = test->priv;
+       int ret;
+
+       priv->gpio_pdev = platform_device_alloc(cirrus_scodec_test_gpio_driver.driver.name, -1);
+       if (!priv->gpio_pdev)
+               return -ENOMEM;
+
+       ret = device_add_software_node(&priv->gpio_pdev->dev, &cirrus_scodec_test_gpio_swnode);
+       if (ret) {
+               platform_device_put(priv->gpio_pdev);
+               KUNIT_FAIL(test, "Failed to add swnode to gpio: %d\n", ret);
+               return ret;
+       }
+
+       ret = platform_device_add(priv->gpio_pdev);
+       if (ret) {
+               platform_device_put(priv->gpio_pdev);
+               KUNIT_FAIL(test, "Failed to add gpio platform device: %d\n", ret);
+               return ret;
+       }
+
+       priv->gpio_priv = dev_get_drvdata(&priv->gpio_pdev->dev);
+       if (!priv->gpio_priv) {
+               platform_device_put(priv->gpio_pdev);
+               KUNIT_FAIL(test, "Failed to get gpio private data: %d\n", ret);
+               return ret;
+       }
+
+       return 0;
+}
+
+static void cirrus_scodec_test_set_gpio_ref_arg(struct software_node_ref_args *arg,
+                                               int gpio_num)
+{
+       struct software_node_ref_args template =
+               SOFTWARE_NODE_REFERENCE(&cirrus_scodec_test_gpio_swnode, gpio_num, 0);
+
+       *arg = template;
+}
+
+static int cirrus_scodec_test_set_spkid_swnode(struct kunit *test,
+                                              struct device *dev,
+                                              struct software_node_ref_args *args,
+                                              int num_args)
+{
+       const struct property_entry props_template[] = {
+               PROPERTY_ENTRY_REF_ARRAY_LEN("spk-id-gpios", args, num_args),
+               { }
+       };
+       struct property_entry *props;
+       struct software_node *node;
+
+       node = kunit_kzalloc(test, sizeof(*node), GFP_KERNEL);
+       if (!node)
+               return -ENOMEM;
+
+       props = kunit_kzalloc(test, sizeof(props_template), GFP_KERNEL);
+       if (!props)
+               return -ENOMEM;
+
+       memcpy(props, props_template, sizeof(props_template));
+       node->properties = props;
+
+       return device_add_software_node(dev, node);
+}
+
+struct cirrus_scodec_test_spkid_param {
+       int num_amps;
+       int gpios_per_amp;
+       int num_amps_sharing;
+};
+
+static void cirrus_scodec_test_spkid_parse(struct kunit *test)
+{
+       struct cirrus_scodec_test_priv *priv = test->priv;
+       const struct cirrus_scodec_test_spkid_param *param = test->param_value;
+       int num_spk_id_refs = param->num_amps * param->gpios_per_amp;
+       struct software_node_ref_args *refs;
+       struct device *dev = &priv->amp_pdev.dev;
+       unsigned int v;
+       int i, ret;
+
+       refs = kunit_kcalloc(test, num_spk_id_refs, sizeof(*refs), GFP_KERNEL);
+       KUNIT_ASSERT_NOT_NULL(test, refs);
+
+       for (i = 0, v = 0; i < num_spk_id_refs; ) {
+               cirrus_scodec_test_set_gpio_ref_arg(&refs[i++], v++);
+
+               /*
+                * If amps are sharing GPIOs repeat the last set of
+                * GPIOs until we've done that number of amps.
+                * We have done all GPIOs for an amp when i is a multiple
+                * of gpios_per_amp.
+                * We have done all amps sharing the same GPIOs when i is
+                * a multiple of (gpios_per_amp * num_amps_sharing).
+                */
+               if (!(i % param->gpios_per_amp) &&
+                   (i % (param->gpios_per_amp * param->num_amps_sharing)))
+                       v -= param->gpios_per_amp;
+       }
+
+       ret = cirrus_scodec_test_set_spkid_swnode(test, dev, refs, num_spk_id_refs);
+       KUNIT_EXPECT_EQ_MSG(test, ret, 0, "Failed to add swnode\n");
+
+       for (i = 0; i < param->num_amps; ++i) {
+               for (v = 0; v < (1 << param->gpios_per_amp); ++v) {
+                       /* Set only the GPIO bits used by this amp */
+                       priv->gpio_priv->pin_state =
+                               v << (param->gpios_per_amp * (i / param->num_amps_sharing));
+
+                       ret = cirrus_scodec_get_speaker_id(dev, i, param->num_amps, -1);
+                       KUNIT_EXPECT_EQ_MSG(test, ret, v,
+                                           "get_speaker_id failed amp:%d pin_state:%#x\n",
+                                           i, priv->gpio_priv->pin_state);
+               }
+       }
+}
+
+static void cirrus_scodec_test_no_spkid(struct kunit *test)
+{
+       struct cirrus_scodec_test_priv *priv = test->priv;
+       struct device *dev = &priv->amp_pdev.dev;
+       int ret;
+
+       ret = cirrus_scodec_get_speaker_id(dev, 0, 4, -1);
+       KUNIT_EXPECT_EQ(test, ret, -ENOENT);
+}
+
+static void cirrus_scodec_test_dev_release(struct device *dev)
+{
+}
+
+static int cirrus_scodec_test_case_init(struct kunit *test)
+{
+       struct cirrus_scodec_test_priv *priv;
+       int ret;
+
+       priv = kunit_kzalloc(test, sizeof(*priv), GFP_KERNEL);
+       if (!priv)
+               return -ENOMEM;
+
+       test->priv = priv;
+
+       /* Create dummy GPIO */
+       ret = cirrus_scodec_test_create_gpio(test);
+       if (ret < 0)
+               return ret;
+
+       /* Create dummy amp driver dev */
+       priv->amp_pdev.name = "cirrus_scodec_test_amp_drv";
+       priv->amp_pdev.id = -1;
+       priv->amp_pdev.dev.release = cirrus_scodec_test_dev_release;
+       ret = platform_device_register(&priv->amp_pdev);
+       KUNIT_ASSERT_GE_MSG(test, ret, 0, "Failed to register amp platform device\n");
+
+       return 0;
+}
+
+static void cirrus_scodec_test_case_exit(struct kunit *test)
+{
+       struct cirrus_scodec_test_priv *priv = test->priv;
+
+       if (priv->amp_pdev.name)
+               platform_device_unregister(&priv->amp_pdev);
+
+       if (priv->gpio_pdev) {
+               device_remove_software_node(&priv->gpio_pdev->dev);
+               platform_device_unregister(priv->gpio_pdev);
+       }
+}
+
+static int cirrus_scodec_test_suite_init(struct kunit_suite *suite)
+{
+       int ret;
+
+       /* Register mock GPIO driver */
+       ret = platform_driver_register(&cirrus_scodec_test_gpio_driver);
+       if (ret < 0) {
+               kunit_err(suite, "Failed to register gpio platform driver, %d\n", ret);
+               return ret;
+       }
+
+       return 0;
+}
+
+static void cirrus_scodec_test_suite_exit(struct kunit_suite *suite)
+{
+       platform_driver_unregister(&cirrus_scodec_test_gpio_driver);
+}
+
+static const struct cirrus_scodec_test_spkid_param cirrus_scodec_test_spkid_param_cases[] = {
+       { .num_amps = 2, .gpios_per_amp = 1, .num_amps_sharing = 1 },
+       { .num_amps = 2, .gpios_per_amp = 2, .num_amps_sharing = 1 },
+       { .num_amps = 2, .gpios_per_amp = 3, .num_amps_sharing = 1 },
+       { .num_amps = 2, .gpios_per_amp = 4, .num_amps_sharing = 1 },
+       { .num_amps = 3, .gpios_per_amp = 1, .num_amps_sharing = 1 },
+       { .num_amps = 3, .gpios_per_amp = 2, .num_amps_sharing = 1 },
+       { .num_amps = 3, .gpios_per_amp = 3, .num_amps_sharing = 1 },
+       { .num_amps = 3, .gpios_per_amp = 4, .num_amps_sharing = 1 },
+       { .num_amps = 4, .gpios_per_amp = 1, .num_amps_sharing = 1 },
+       { .num_amps = 4, .gpios_per_amp = 2, .num_amps_sharing = 1 },
+       { .num_amps = 4, .gpios_per_amp = 3, .num_amps_sharing = 1 },
+       { .num_amps = 4, .gpios_per_amp = 4, .num_amps_sharing = 1 },
+
+       /* Same GPIO shared by all amps */
+       { .num_amps = 2, .gpios_per_amp = 1, .num_amps_sharing = 2 },
+       { .num_amps = 2, .gpios_per_amp = 2, .num_amps_sharing = 2 },
+       { .num_amps = 2, .gpios_per_amp = 3, .num_amps_sharing = 2 },
+       { .num_amps = 2, .gpios_per_amp = 4, .num_amps_sharing = 2 },
+       { .num_amps = 3, .gpios_per_amp = 1, .num_amps_sharing = 3 },
+       { .num_amps = 3, .gpios_per_amp = 2, .num_amps_sharing = 3 },
+       { .num_amps = 3, .gpios_per_amp = 3, .num_amps_sharing = 3 },
+       { .num_amps = 3, .gpios_per_amp = 4, .num_amps_sharing = 3 },
+       { .num_amps = 4, .gpios_per_amp = 1, .num_amps_sharing = 4 },
+       { .num_amps = 4, .gpios_per_amp = 2, .num_amps_sharing = 4 },
+       { .num_amps = 4, .gpios_per_amp = 3, .num_amps_sharing = 4 },
+       { .num_amps = 4, .gpios_per_amp = 4, .num_amps_sharing = 4 },
+
+       /* Two sets of shared GPIOs */
+       { .num_amps = 4, .gpios_per_amp = 1, .num_amps_sharing = 2 },
+       { .num_amps = 4, .gpios_per_amp = 2, .num_amps_sharing = 2 },
+       { .num_amps = 4, .gpios_per_amp = 3, .num_amps_sharing = 2 },
+       { .num_amps = 4, .gpios_per_amp = 4, .num_amps_sharing = 2 },
+};
+
+static void cirrus_scodec_test_spkid_param_desc(const struct cirrus_scodec_test_spkid_param *param,
+                                               char *desc)
+{
+       snprintf(desc, KUNIT_PARAM_DESC_SIZE, "amps:%d gpios_per_amp:%d num_amps_sharing:%d",
+                param->num_amps, param->gpios_per_amp, param->num_amps_sharing);
+}
+
+KUNIT_ARRAY_PARAM(cirrus_scodec_test_spkid, cirrus_scodec_test_spkid_param_cases,
+                 cirrus_scodec_test_spkid_param_desc);
+
+static struct kunit_case cirrus_scodec_test_cases[] = {
+       KUNIT_CASE_PARAM(cirrus_scodec_test_spkid_parse, cirrus_scodec_test_spkid_gen_params),
+       KUNIT_CASE(cirrus_scodec_test_no_spkid),
+       { } /* terminator */
+};
+
+static struct kunit_suite cirrus_scodec_test_suite = {
+       .name = "snd-hda-scodec-cs35l56-test",
+       .suite_init = cirrus_scodec_test_suite_init,
+       .suite_exit = cirrus_scodec_test_suite_exit,
+       .init = cirrus_scodec_test_case_init,
+       .exit = cirrus_scodec_test_case_exit,
+       .test_cases = cirrus_scodec_test_cases,
+};
+
+kunit_test_suite(cirrus_scodec_test_suite);
+
+MODULE_IMPORT_NS(SND_HDA_CIRRUS_SCODEC);
+MODULE_AUTHOR("Richard Fitzgerald <rf@opensource.cirrus.com>");
+MODULE_LICENSE("GPL");