[PATCH 1/2] regulator: Add coupled regulator

[Maxime Ripard]

Some boards, in order to power devices that have a quite high power
consumption, wire multiple regulators in parallel.

In such a case, the regulators need to be kept in sync, all of them being
enabled or disabled in parallel.

This also requires to expose only the voltages that are common to all the
regulators.

Eventually support for changing the voltage in parallel should be added
too, possibly with delays between each other to avoid having a too brutal
peak consumption.

Signed-off-by: Maxime Ripard <maxime.ripard@xxxxxxxxxxxxxxxxxx>
---
 drivers/regulator/Kconfig                     |   7 +
 drivers/regulator/Makefile                    |   1 +
 drivers/regulator/coupled-voltage-regulator.c | 241 ++++++++++++++++++++++++++
 3 files changed, 249 insertions(+)
 create mode 100644 drivers/regulator/coupled-voltage-regulator.c

diff --git a/drivers/regulator/Kconfig b/drivers/regulator/Kconfig
index 8df0b0e62976..6ba7bc8fda13 100644
--- a/drivers/regulator/Kconfig
+++ b/drivers/regulator/Kconfig
@@ -35,6 +35,13 @@ config REGULATOR_FIXED_VOLTAGE
 	  useful for systems which use a combination of software
 	  managed regulators and simple non-configurable regulators.
 
+config REGULATOR_COUPLED_VOLTAGE
+	tristate "Coupled voltage regulator support"
+	help
+	  This driver provides support for regulators that are an
+	  aggregate of other regulators in the system, and need to
+	  keep them all in sync.
+
 config REGULATOR_VIRTUAL_CONSUMER
 	tristate "Virtual regulator consumer support"
 	help
diff --git a/drivers/regulator/Makefile b/drivers/regulator/Makefile
index 0f8174913c17..c05839257386 100644
--- a/drivers/regulator/Makefile
+++ b/drivers/regulator/Makefile
@@ -22,6 +22,7 @@ obj-$(CONFIG_REGULATOR_AS3711) += as3711-regulator.o
 obj-$(CONFIG_REGULATOR_AS3722) += as3722-regulator.o
 obj-$(CONFIG_REGULATOR_AXP20X) += axp20x-regulator.o
 obj-$(CONFIG_REGULATOR_BCM590XX) += bcm590xx-regulator.o
+obj-$(CONFIG_REGULATOR_COUPLED_VOLTAGE) += coupled-voltage-regulator.o
 obj-$(CONFIG_REGULATOR_DA903X)	+= da903x.o
 obj-$(CONFIG_REGULATOR_DA9052)	+= da9052-regulator.o
 obj-$(CONFIG_REGULATOR_DA9055)	+= da9055-regulator.o
diff --git a/drivers/regulator/coupled-voltage-regulator.c b/drivers/regulator/coupled-voltage-regulator.c
new file mode 100644
index 000000000000..dc7aa2aca7e6
--- /dev/null
+++ b/drivers/regulator/coupled-voltage-regulator.c
@@ -0,0 +1,241 @@
+/*
+ * Copyright 2015 Free Electrons
+ * Copyright 2015 NextThing Co.
+ *
+ * Author: Maxime Ripard <maxime.ripard@xxxxxxxxxxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ */
+
+#include <linux/module.h>
+#include <linux/mod_devicetable.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+
+#include <linux/regulator/consumer.h>
+#include <linux/regulator/driver.h>
+#include <linux/regulator/of_regulator.h>
+
+#define COUPLED_REGULATOR_MAX_SUPPLIES	16
+
+struct coupled_regulator {
+	struct regulator	**regulators;
+	int			n_regulators;
+
+	int			*voltages;
+	int			n_voltages;
+};
+
+static int coupled_regulator_disable(struct regulator_dev *rdev)
+{
+	struct coupled_regulator *creg = rdev_get_drvdata(rdev);
+	int ret, i;
+
+	for (i = 0; i < creg->n_regulators; i++) {
+		ret = regulator_disable(creg->regulators[i]);
+		if (ret)
+			break;
+	}
+
+	return ret;
+}
+
+static int coupled_regulator_enable(struct regulator_dev *rdev)
+{
+	struct coupled_regulator *creg = rdev_get_drvdata(rdev);
+	int ret, i;
+
+	for (i = 0; i < creg->n_regulators; i++) {
+		ret = regulator_enable(creg->regulators[i]);
+		if (ret)
+			break;
+	}
+
+	return ret;
+}
+
+static int coupled_regulator_is_enabled(struct regulator_dev *rdev)
+{
+	struct coupled_regulator *creg = rdev_get_drvdata(rdev);
+	int ret = 0, i;
+
+	for (i = 0; i < creg->n_regulators; i++) {
+		ret &= regulator_is_enabled(creg->regulators[i]);
+		if (ret < 0)
+			break;
+	}
+
+	return ret;
+}
+
+static int coupled_regulator_list_voltage(struct regulator_dev *rdev,
+					  unsigned int selector)
+{
+	struct coupled_regulator *creg = rdev_get_drvdata(rdev);
+
+	if (selector >= creg->n_voltages)
+		return -EINVAL;
+
+	return creg->voltages[selector];
+}
+
+static struct regulator_ops coupled_regulator_ops = {
+	.enable			= coupled_regulator_enable,
+	.disable		= coupled_regulator_disable,
+	.is_enabled		= coupled_regulator_is_enabled,
+	.list_voltage		= coupled_regulator_list_voltage,
+};
+
+static struct regulator_desc coupled_regulator_desc = {
+	.name		= "coupled-voltage-regulator",
+	.type		= REGULATOR_VOLTAGE,
+	.ops		= &coupled_regulator_ops,
+	.owner		= THIS_MODULE,
+};
+
+static int coupled_regulator_probe(struct platform_device *pdev)
+{
+	const struct regulator_init_data *init_data;
+	struct coupled_regulator *creg;
+	struct regulator_config config = { };
+	struct regulator_dev *regulator;
+	struct regulator_desc *desc;
+	struct device_node *np = pdev->dev.of_node;
+	int max_voltages, i;
+
+	if (!np) {
+		dev_err(&pdev->dev, "Device Tree node missing\n");
+		return -EINVAL;
+	}
+
+	creg = devm_kzalloc(&pdev->dev, sizeof(*creg), GFP_KERNEL);
+	if (!creg)
+		return -ENOMEM;
+
+	init_data = of_get_regulator_init_data(&pdev->dev, np,
+					       &coupled_regulator_desc);
+	if (!init_data)
+		return -ENOMEM;
+
+	config.of_node = np;
+	config.dev = &pdev->dev;
+	config.driver_data = creg;
+	config.init_data = init_data;
+
+	for (i = 0; i < COUPLED_REGULATOR_MAX_SUPPLIES; i++) {
+		char *propname = kasprintf(GFP_KERNEL, "vin%d-supply", i);
+		const void *prop = of_get_property(np, propname, NULL);
+		kfree(propname);
+
+		if (!prop) {
+			creg->n_regulators = i;
+			break;
+		}
+	}
+
+	dev_dbg(&pdev->dev, "Found %d parent regulators\n",
+		creg->n_regulators);
+
+	if (!creg->n_regulators) {
+		dev_err(&pdev->dev, "No parent regulators listed\n");
+		return -EINVAL;
+	}
+
+	creg->regulators = devm_kcalloc(&pdev->dev, creg->n_regulators,
+					sizeof(*creg->regulators), GFP_KERNEL);
+	if (!creg->regulators)
+		return -ENOMEM;
+
+	for (i = 0; i < creg->n_regulators; i++) {
+		char *propname = kasprintf(GFP_KERNEL, "vin%d", i);
+
+		dev_dbg(&pdev->dev, "Trying to get supply %s\n", propname);
+
+		creg->regulators[i] = devm_regulator_get(&pdev->dev, propname);
+		kfree(propname);
+
+		if (IS_ERR(creg->regulators[i])) {
+			dev_err(&pdev->dev, "Couldn't get regulator vin%d\n",
+				i);
+			return PTR_ERR(creg->regulators[i]);
+		}
+	}
+
+	/*
+	 * Since we want only to expose voltages that can be set on
+	 * all the regulators, we won't have more voltages supported
+	 * than the number of voltages supported by the first
+	 * regulator in our list
+	 */
+	max_voltages = regulator_count_voltages(creg->regulators[0]);
+
+	creg->voltages = devm_kcalloc(&pdev->dev, max_voltages, sizeof(int),
+				      GFP_KERNEL);
+
+	/* Build up list of supported voltages */
+	for (i = 0; i < max_voltages; i++) {
+		int voltage = regulator_list_voltage(creg->regulators[0], i);
+		bool usable = true;
+		int j;
+
+		if (voltage <= 0)
+			continue;
+
+		dev_dbg(&pdev->dev, "Checking voltage %d...\n", voltage);
+
+		for (j = 1; j < creg->n_regulators; j++) {
+			if (!regulator_is_supported_voltage(creg->regulators[j],
+							    voltage, voltage)) {
+				usable = false;
+				break;
+			}
+		}
+
+		if (usable) {
+			creg->voltages[creg->n_voltages++] = voltage;
+			dev_dbg(&pdev->dev,
+				 "Adding voltage %d to the list of supported voltages\n",
+				 voltage);
+		}
+	}
+
+	dev_dbg(&pdev->dev, "Supporting %d voltages\n", creg->n_voltages);
+
+	desc = devm_kmemdup(&pdev->dev, &coupled_regulator_desc,
+			    sizeof(coupled_regulator_desc), GFP_KERNEL);
+	if (!desc)
+		return -ENOMEM;
+	desc->n_voltages = creg->n_voltages;
+
+	regulator = devm_regulator_register(&pdev->dev, desc, &config);
+	if (IS_ERR(regulator)) {
+		dev_err(&pdev->dev, "Failed to register regulator %s\n",
+			coupled_regulator_desc.name);
+		return PTR_ERR(regulator);
+	}
+
+	return 0;
+}
+
+static struct of_device_id coupled_regulator_of_match[] = {
+	{ .compatible = "coupled-voltage-regulator" },
+	{ /* Sentinel */ },
+};
+
+static struct platform_driver coupled_regulator_driver = {
+	.probe	= coupled_regulator_probe,
+
+	.driver = {
+		.name		= "coupled-voltage-regulator",
+		.of_match_table	= coupled_regulator_of_match,
+	},
+};
+module_platform_driver(coupled_regulator_driver);
+
+MODULE_AUTHOR("Maxime Ripard <maxime.ripard@xxxxxxxxxxxxxxxxxx>");
+MODULE_DESCRIPTION("Coupled Regulator Driver");
+MODULE_LICENSE("GPL");
-- 
2.6.3

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