[PATCH v2 1/2] regulator: Add coupled regulator

From: Maxime Ripard
Date: Tue Jan 12 2016 - 08:38:04 EST

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>
---
.../bindings/regulator/coupled-voltage.txt | 18 ++
drivers/regulator/Kconfig | 8 +
drivers/regulator/Makefile | 1 +
drivers/regulator/coupled-voltage-regulator.c | 299 +++++++++++++++++++++
4 files changed, 326 insertions(+)
create mode 100644 Documentation/devicetree/bindings/regulator/coupled-voltage.txt
create mode 100644 drivers/regulator/coupled-voltage-regulator.c

diff --git a/Documentation/devicetree/bindings/regulator/coupled-voltage.txt b/Documentation/devicetree/bindings/regulator/coupled-voltage.txt
new file mode 100644
index 000000000000..f5401aab52f2
--- /dev/null
+++ b/Documentation/devicetree/bindings/regulator/coupled-voltage.txt
@@ -0,0 +1,18 @@
+Coupled voltage regulators
+
+Required properties:
+- compatible : Must be "coupled-voltage-regulator".
+
+Optional properties:
+- vinX-supply : Phandle to the regulators it aggregates
+
+Any property defined as part of the core regulator binding defined in
+regulator.txt can also be used.
+
+Example:
+ vcc_wifi: wifi_reg {
+ compatible = "coupled-voltage-regulator";
+ regulator-name = "vcc-wifi";
+ vin0-supply = <&reg_ldo3>;
+ vin1-supply = <&reg_ldo4>;
+ };
diff --git a/drivers/regulator/Kconfig b/drivers/regulator/Kconfig
index 7df9da82f592..5d18c9a6169f 100644
--- a/drivers/regulator/Kconfig
+++ b/drivers/regulator/Kconfig
@@ -35,6 +35,14 @@ 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"
+ depends on OF
+ 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 980b1943fa81..76c9728113f7 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..c1bf798abfef
--- /dev/null
+++ b/drivers/regulator/coupled-voltage-regulator.c
@@ -0,0 +1,299 @@
+/*
+ * 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 - Private data for the driver
+ * @regulators: array of struct regulator aggregated
+ * @n_regulators: number of regulators aggregated
+ * @voltages: array of voltages common to all the regulators
+ * @n_voltages: number of common voltages
+ */
+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) {
+ dev_warn(&rdev->dev, "Couldn't disable our regulator\n");
+ goto err_unwind;
+ }
+ }
+
+ return 0;
+
+err_unwind:
+ /*
+ * In case a regulator cannot disable, unwind everything to
+ * make sure we're in a consistent (and probably safe) state
+ */
+ for (; i >= 0; i--) {
+ int en_ret = regulator_enable(creg->regulators[i]);
+ if (en_ret)
+ dev_warn(&rdev->dev,
+ "Couldn't unwind disable operation for our regulator\n");
+ }
+
+ 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) {
+ dev_warn(&rdev->dev, "Couldn't enable our regulator\n");
+ goto err_unwind;
+ }
+ }
+
+ return 0;
+
+err_unwind:
+ /*
+ * In case a regulator cannot enable, unwind everything to
+ * make sure we're in a consistent (and probably safe) state
+ */
+ for (; i >= 0; i--) {
+ int en_ret = regulator_disable(creg->regulators[i]);
+ if (en_ret)
+ dev_warn(&rdev->dev,
+ "Couldn't unwind enable operation for our regulator\n");
+ }
+
+ return ret;
+}
+
+static int coupled_regulator_is_enabled(struct regulator_dev *rdev)
+{
+ struct coupled_regulator *creg = rdev_get_drvdata(rdev);
+ int i;
+
+ for (i = 0; i < creg->n_regulators; i++) {
+ int ret = regulator_is_enabled(creg->regulators[i]);
+
+ /*
+ * If there's at least one regulator that isn't
+ * enabled or returns an error, return that,
+ * otherwise, just go on.
+ */
+ if (ret <= 0)
+ return ret;
+ }
+
+ return 1;
+}
+
+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]);
+ }
+
+ /*
+ * FIXME: We should probably be doing something
+ * smarter here to avoid having a bunch of regulators
+ * disabled and a bunch enabled.
+ */
+ if (regulator_is_enabled(creg->regulators[i])) {
+ int ret = regulator_enable(creg->regulators[i]);
+ if (ret) {
+ regulator_put(creg->regulators[i]);
+ return ret;
+ }
+ }
+ }
+
+ /*
+ * 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 */ },
+};
+MODULE_DEVICE_TABLE(of, coupled_regulator_of_match);
+
+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");
--
2.6.4