linux-kernel - [RFC PATCH v1 2/2] regulator: Introduce dummy regulator consumer driver

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Message-ID: <20250607212654.126412-3-alex.vinarskis@gmail.com>
Date: Sat,  7 Jun 2025 23:25:39 +0200
From: Aleksandrs Vinarskis <alex.vinarskis@...il.com>
To: Aleksandrs Vinarskis <alex.vinarskis@...il.com>,
	Mark Brown <broonie@...nel.org>,
	linux-kernel@...r.kernel.org,
	devicetree@...r.kernel.org
Cc: Liam Girdwood <lgirdwood@...il.com>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	jens.glathe@...schoolsolutions.biz,
	konrad.dybcio@....qualcomm.com
Subject: [RFC PATCH v1 2/2] regulator: Introduce dummy regulator consumer driver

Introduce a very simple dummy consumer driver. Designed to consume
a single regulator 'vdd', the driver will power-on on probe and PM
suspend (if supported), power-off on remove and PM resume (if enabled).

Signed-off-by: Aleksandrs Vinarskis <alex.vinarskis@...il.com>
---
 drivers/regulator/Kconfig          |  9 ++++
 drivers/regulator/Makefile         |  1 +
 drivers/regulator/dummy-consumer.c | 85 ++++++++++++++++++++++++++++++
 3 files changed, 95 insertions(+)
 create mode 100644 drivers/regulator/dummy-consumer.c

diff --git a/drivers/regulator/Kconfig b/drivers/regulator/Kconfig
index 6d8988387da4..eb907ecbcbe8 100644
--- a/drivers/regulator/Kconfig
+++ b/drivers/regulator/Kconfig
@@ -30,6 +30,15 @@ config REGULATOR_DEBUG
 	help
 	  Say yes here to enable debugging support.
 
+config REGULATOR_DUMMY_CONSUMER
+	tristate "Dummy regulator consumer support"
+	help
+	  This driver provides a dummy consumer for a device behind an
+	  USB phy (for example) that needs power supplies, but has no
+	  own device node since it's enumerated by USB.
+
+	  If unsure, say no.
+
 config REGULATOR_FIXED_VOLTAGE
 	tristate "Fixed voltage regulator support"
 	help
diff --git a/drivers/regulator/Makefile b/drivers/regulator/Makefile
index c0bc7a0f4e67..e1d1029fd87a 100644
--- a/drivers/regulator/Makefile
+++ b/drivers/regulator/Makefile
@@ -5,6 +5,7 @@
 
 
 obj-$(CONFIG_REGULATOR) += core.o dummy.o fixed-helper.o helpers.o devres.o irq_helpers.o
+obj-$(CONFIG_REGULATOR_DUMMY_CONSUMER) += dummy-consumer.o
 obj-$(CONFIG_REGULATOR_NETLINK_EVENTS) += event.o
 obj-$(CONFIG_OF) += of_regulator.o
 obj-$(CONFIG_REGULATOR_FIXED_VOLTAGE) += fixed.o
diff --git a/drivers/regulator/dummy-consumer.c b/drivers/regulator/dummy-consumer.c
new file mode 100644
index 000000000000..813c7abce660
--- /dev/null
+++ b/drivers/regulator/dummy-consumer.c
@@ -0,0 +1,85 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2025, Aleksandrs Vinarskis
+ */
+
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/pm.h>
+#include <linux/regulator/consumer.h>
+
+struct dummy_consumer_data {
+	struct regulator *regulator;
+};
+
+static int dummy_consumer_probe(struct platform_device *pdev)
+{
+	struct dummy_consumer_data *data;
+	int ret;
+
+	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->regulator = devm_regulator_get(&pdev->dev, "vdd");
+	if (IS_ERR(data->regulator)) {
+		dev_err(&pdev->dev, "Failed to get regulator\n");
+		return PTR_ERR(data->regulator);
+	}
+
+	ret = regulator_enable(data->regulator);
+	if (ret) {
+		dev_err(&pdev->dev, "Failed to enable regulator: %d\n", ret);
+		return ret;
+	}
+
+	platform_set_drvdata(pdev, data);
+
+	dev_dbg(&pdev->dev, "Dummy regulator consumer initialized\n");
+	return 0;
+}
+
+static void dummy_consumer_remove(struct platform_device *pdev)
+{
+	struct dummy_consumer_data *data = platform_get_drvdata(pdev);
+
+	regulator_disable(data->regulator);
+}
+
+static int dummy_consumer_resume(struct device *dev)
+{
+	struct dummy_consumer_data *data = dev_get_drvdata(dev);
+
+	return regulator_enable(data->regulator);
+}
+
+static int dummy_consumer_suspend(struct device *dev)
+{
+	struct dummy_consumer_data *data = dev_get_drvdata(dev);
+
+	return regulator_disable(data->regulator);
+}
+
+static DEFINE_SIMPLE_DEV_PM_OPS(dummy_consumer_pm, dummy_consumer_suspend, dummy_consumer_resume);
+
+static const struct of_device_id dummy_consumer_of_match[] = {
+	{ .compatible = "regulator-dummy-consumer", },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, dummy_consumer_of_match);
+
+static struct platform_driver dummy_consumer_driver = {
+	.driver = {
+		.name = "regulator-dummy-consumer",
+		.of_match_table = dummy_consumer_of_match,
+		.pm = pm_sleep_ptr(&dummy_consumer_pm),
+	},
+	.probe = dummy_consumer_probe,
+	.remove = dummy_consumer_remove,
+};
+module_platform_driver(dummy_consumer_driver);
+
+MODULE_AUTHOR("Aleksandrs Vinarskis <alex.vinarskis@...il.com>");
+MODULE_DESCRIPTION("Dummy regulator consumer driver");
+MODULE_LICENSE("GPL");
-- 
2.45.2