[PATCH v2 0/3] regulator: Add DT support for regulator-output connectors

[PATCH v2 0/3] regulator: Add DT support for regulator-output connectors

[Zev Weiss]

Hello,

This is v2 of my recent series adding support for userspace-controlled
regulator-supplied power outputs [2].  This is an important feature
for some kinds of BMC (baseboard management controller) systems where
the BMC provides an operator with manual control of a set of DC power
outputs.

As in a broadly similar patchset that was recently almost merged [0],
this takes the approach of providing support by extending the existing
userspace-consumer regulator driver.  A couple questions about the
userspace-consumer driver came up along the way, however.

First, how (if at all) is it currently being used?  It appears the
last in-tree use of it was removed a bit over two years ago in commit
9d3239147d6d ("ARM: pxa: remove Compulab pxa2xx boards").  Aside from
just adding DT support I've made a couple small tweaks to the driver
in patch 3 that I hope are compatible with any current usage, but
without any extant examples to look at it's kind of hard to say.

Second, how critical is its support for controlling multiple
regulators?  (i.e. its use of regulator_bulk_data and friends instead
of a single struct regulator.)  As far as I can see every in-tree use
of it that's ever existed has used num_supplies = 1.  If it's not
important to retain, patch 1 of this series could be supplanted by one
that instead simplifies the driver slightly by removing that
functionality.

The DT binding added in patch 2 is essentially identical to one I
posted in a previous patchset that had an R-B from Rob [1], but has
had some minor rewording and been moved from the extcon subsystem to
the regulator subsystem.

Changes since v1 [2]:
 - removed 'regulator-leave-on' DT property
 - added .is_visible method to hide sysfs 'name' property when it's
   NULL


Thanks,
Zev

[0] https://lore.kernel.org/all/20220707081826.953449-4-Naresh.Solanki@9elements.com/
[1] https://lore.kernel.org/linux-kernel/20220505232557.10936-2-zev@bewilderbeest.net/
[2] https://lore.kernel.org/openbmc/20220925220319.12572-1-zev@bewilderbeest.net/

Zev Weiss (3):
  regulator: devres: Add devm_regulator_bulk_get_exclusive()
  dt-bindings: regulator: Add regulator-output binding
  regulator: userspace-consumer: Handle regulator-output DT nodes

 .../bindings/regulator/regulator-output.yaml  | 39 +++++++++++
 drivers/regulator/core.c                      | 42 +++++++-----
 drivers/regulator/devres.c                    | 66 ++++++++++++++-----
 drivers/regulator/internal.h                  |  2 +
 drivers/regulator/userspace-consumer.c        | 60 +++++++++++++++--
 include/linux/regulator/consumer.h            |  2 +
 include/linux/regulator/userspace-consumer.h  |  1 +
 7 files changed, 169 insertions(+), 43 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/regulator/regulator-output.yaml

-- 
2.38.1

[PATCH v2 1/3] regulator: devres: Add devm_regulator_bulk_get_exclusive()

[Zev Weiss]

We had an exclusive variant of the devm_regulator_get() API, but no
corresponding variant for the bulk API; let's add one now.  We add a
generalized version of the existing regulator_bulk_get() function that
additionally takes a get_type parameter and redefine
regulator_bulk_get() in terms of it, then do similarly with
devm_regulator_bulk_get(), and finally add the new
devm_regulator_bulk_get_exclusive().

Signed-off-by: Zev Weiss <zev@bewilderbeest.net>
---
 drivers/regulator/core.c           | 42 +++++++++++--------
 drivers/regulator/devres.c         | 66 ++++++++++++++++++++++--------
 drivers/regulator/internal.h       |  2 +
 include/linux/regulator/consumer.h |  2 +
 4 files changed, 76 insertions(+), 36 deletions(-)

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index bcccad8f7516..704f91720dfe 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -4778,22 +4778,8 @@ static int _notifier_call_chain(struct regulator_dev *rdev,
 	return blocking_notifier_call_chain(&rdev->notifier, event, data);
 }
 
-/**
- * regulator_bulk_get - get multiple regulator consumers
- *
- * @dev:           Device to supply
- * @num_consumers: Number of consumers to register
- * @consumers:     Configuration of consumers; clients are stored here.
- *
- * @return 0 on success, an errno on failure.
- *
- * This helper function allows drivers to get several regulator
- * consumers in one operation.  If any of the regulators cannot be
- * acquired then any regulators that were allocated will be freed
- * before returning to the caller.
- */
-int regulator_bulk_get(struct device *dev, int num_consumers,
-		       struct regulator_bulk_data *consumers)
+int _regulator_bulk_get(struct device *dev, int num_consumers,
+			struct regulator_bulk_data *consumers, enum regulator_get_type get_type)
 {
 	int i;
 	int ret;
@@ -4802,8 +4788,8 @@ int regulator_bulk_get(struct device *dev, int num_consumers,
 		consumers[i].consumer = NULL;
 
 	for (i = 0; i < num_consumers; i++) {
-		consumers[i].consumer = regulator_get(dev,
-						      consumers[i].supply);
+		consumers[i].consumer = _regulator_get(dev,
+						       consumers[i].supply, get_type);
 		if (IS_ERR(consumers[i].consumer)) {
 			ret = dev_err_probe(dev, PTR_ERR(consumers[i].consumer),
 					    "Failed to get supply '%s'",
@@ -4830,6 +4816,26 @@ int regulator_bulk_get(struct device *dev, int num_consumers,
 
 	return ret;
 }
+
+/**
+ * regulator_bulk_get - get multiple regulator consumers
+ *
+ * @dev:           Device to supply
+ * @num_consumers: Number of consumers to register
+ * @consumers:     Configuration of consumers; clients are stored here.
+ *
+ * @return 0 on success, an errno on failure.
+ *
+ * This helper function allows drivers to get several regulator
+ * consumers in one operation.  If any of the regulators cannot be
+ * acquired then any regulators that were allocated will be freed
+ * before returning to the caller.
+ */
+int regulator_bulk_get(struct device *dev, int num_consumers,
+		       struct regulator_bulk_data *consumers)
+{
+	return _regulator_bulk_get(dev, num_consumers, consumers, NORMAL_GET);
+}
 EXPORT_SYMBOL_GPL(regulator_bulk_get);
 
 static void regulator_bulk_enable_async(void *data, async_cookie_t cookie)
diff --git a/drivers/regulator/devres.c b/drivers/regulator/devres.c
index 3265e75e97ab..fec0398d98b0 100644
--- a/drivers/regulator/devres.c
+++ b/drivers/regulator/devres.c
@@ -186,23 +186,9 @@ static void devm_regulator_bulk_release(struct device *dev, void *res)
 	regulator_bulk_free(devres->num_consumers, devres->consumers);
 }
 
-/**
- * devm_regulator_bulk_get - managed get multiple regulator consumers
- *
- * @dev:           device to supply
- * @num_consumers: number of consumers to register
- * @consumers:     configuration of consumers; clients are stored here.
- *
- * @return 0 on success, an errno on failure.
- *
- * This helper function allows drivers to get several regulator
- * consumers in one operation with management, the regulators will
- * automatically be freed when the device is unbound.  If any of the
- * regulators cannot be acquired then any regulators that were
- * allocated will be freed before returning to the caller.
- */
-int devm_regulator_bulk_get(struct device *dev, int num_consumers,
-			    struct regulator_bulk_data *consumers)
+static int _devm_regulator_bulk_get(struct device *dev, int num_consumers,
+				    struct regulator_bulk_data *consumers,
+				    enum regulator_get_type get_type)
 {
 	struct regulator_bulk_devres *devres;
 	int ret;
@@ -212,7 +198,7 @@ int devm_regulator_bulk_get(struct device *dev, int num_consumers,
 	if (!devres)
 		return -ENOMEM;
 
-	ret = regulator_bulk_get(dev, num_consumers, consumers);
+	ret = _regulator_bulk_get(dev, num_consumers, consumers, get_type);
 	if (!ret) {
 		devres->consumers = consumers;
 		devres->num_consumers = num_consumers;
@@ -223,8 +209,52 @@ int devm_regulator_bulk_get(struct device *dev, int num_consumers,
 
 	return ret;
 }
+
+/**
+ * devm_regulator_bulk_get - managed get multiple regulator consumers
+ *
+ * @dev:           device to supply
+ * @num_consumers: number of consumers to register
+ * @consumers:     configuration of consumers; clients are stored here.
+ *
+ * @return 0 on success, an errno on failure.
+ *
+ * This helper function allows drivers to get several regulator
+ * consumers in one operation with management, the regulators will
+ * automatically be freed when the device is unbound.  If any of the
+ * regulators cannot be acquired then any regulators that were
+ * allocated will be freed before returning to the caller.
+ */
+int devm_regulator_bulk_get(struct device *dev, int num_consumers,
+			    struct regulator_bulk_data *consumers)
+{
+	return _devm_regulator_bulk_get(dev, num_consumers, consumers, NORMAL_GET);
+}
 EXPORT_SYMBOL_GPL(devm_regulator_bulk_get);
 
+/**
+ * devm_regulator_bulk_get_exclusive - managed exclusive get of multiple
+ * regulator consumers
+ *
+ * @dev:           device to supply
+ * @num_consumers: number of consumers to register
+ * @consumers:     configuration of consumers; clients are stored here.
+ *
+ * @return 0 on success, an errno on failure.
+ *
+ * This helper function allows drivers to exclusively get several
+ * regulator consumers in one operation with management, the regulators
+ * will automatically be freed when the device is unbound.  If any of
+ * the regulators cannot be acquired then any regulators that were
+ * allocated will be freed before returning to the caller.
+ */
+int devm_regulator_bulk_get_exclusive(struct device *dev, int num_consumers,
+				      struct regulator_bulk_data *consumers)
+{
+	return _devm_regulator_bulk_get(dev, num_consumers, consumers, EXCLUSIVE_GET);
+}
+EXPORT_SYMBOL_GPL(devm_regulator_bulk_get_exclusive);
+
 /**
  * devm_regulator_bulk_get_const - devm_regulator_bulk_get() w/ const data
  *
diff --git a/drivers/regulator/internal.h b/drivers/regulator/internal.h
index 1e9c71642143..fb4433068d29 100644
--- a/drivers/regulator/internal.h
+++ b/drivers/regulator/internal.h
@@ -122,4 +122,6 @@ enum regulator_get_type {
 
 struct regulator *_regulator_get(struct device *dev, const char *id,
 				 enum regulator_get_type get_type);
+int _regulator_bulk_get(struct device *dev, int num_consumers,
+			struct regulator_bulk_data *consumers, enum regulator_get_type get_type);
 #endif
diff --git a/include/linux/regulator/consumer.h b/include/linux/regulator/consumer.h
index ee3b4a014611..628a52b8e63f 100644
--- a/include/linux/regulator/consumer.h
+++ b/include/linux/regulator/consumer.h
@@ -247,6 +247,8 @@ int __must_check regulator_bulk_get(struct device *dev, int num_consumers,
 int __must_check devm_regulator_bulk_get(struct device *dev, int num_consumers,
 					 struct regulator_bulk_data *consumers);
 void devm_regulator_bulk_put(struct regulator_bulk_data *consumers);
+int __must_check devm_regulator_bulk_get_exclusive(struct device *dev, int num_consumers,
+						   struct regulator_bulk_data *consumers);
 int __must_check devm_regulator_bulk_get_const(
 	struct device *dev, int num_consumers,
 	const struct regulator_bulk_data *in_consumers,
-- 
2.38.1

[PATCH v2 2/3] dt-bindings: regulator: Add regulator-output binding

[Zev Weiss]

This describes a power output supplied by a regulator, such as a
power outlet on a power distribution unit (PDU).

Signed-off-by: Zev Weiss <zev@bewilderbeest.net>
---

Changes since v1:
 - removed 'regulator-leave-on' property

 .../bindings/regulator/regulator-output.yaml  | 39 +++++++++++++++++++
 1 file changed, 39 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/regulator/regulator-output.yaml

diff --git a/Documentation/devicetree/bindings/regulator/regulator-output.yaml b/Documentation/devicetree/bindings/regulator/regulator-output.yaml
new file mode 100644
index 000000000000..078b37a1a71a
--- /dev/null
+++ b/Documentation/devicetree/bindings/regulator/regulator-output.yaml
@@ -0,0 +1,39 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+
+$id: http://devicetree.org/schemas/regulator/regulator-output.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Regulator output connector
+
+maintainers:
+  - Zev Weiss <zev@bewilderbeest.net>
+
+description: |
+  This describes a power output connector supplied by a regulator,
+  such as a power outlet on a power distribution unit (PDU).  The
+  connector may be standalone or merely one channel or set of pins
+  within a ganged physical connector carrying multiple independent
+  power outputs.
+
+properties:
+  compatible:
+    const: regulator-output
+
+  vout-supply:
+    description:
+      Phandle of the regulator supplying the output.
+
+required:
+  - compatible
+  - vout-supply
+
+additionalProperties: false
+
+examples:
+  - |
+      output {
+          compatible = "regulator-output";
+          vout-supply = <&output_reg>;
+      };
-- 
2.38.1

[PATCH v2 3/3] regulator: userspace-consumer: Handle regulator-output DT nodes

[Zev Weiss]

In addition to adding some fairly simple OF support code, we make some
slight adjustments to the userspace-consumer driver to properly
support use with regulator-output hardware:

 - We now do an exclusive get of the supply regulators so as to
   prevent regulator_init_complete_work from automatically disabling
   them.

 - Instead of assuming that the supply is initially disabled, we now
   query its state to determine the initial value of drvdata->enabled.

Signed-off-by: Zev Weiss <zev@bewilderbeest.net>
---

Changes since v1:
 - removed 'regulator-leave-on' support, instead just setting
   .no_autoswitch if instantiated via DT
 - added .is_visible method to hide 'name' sysfs attribute when it's
   not set

 drivers/regulator/userspace-consumer.c       | 60 +++++++++++++++++---
 include/linux/regulator/userspace-consumer.h |  1 +
 2 files changed, 54 insertions(+), 7 deletions(-)

diff --git a/drivers/regulator/userspace-consumer.c b/drivers/regulator/userspace-consumer.c
index 8ca28664776e..402c8037cf39 100644
--- a/drivers/regulator/userspace-consumer.c
+++ b/drivers/regulator/userspace-consumer.c
@@ -14,6 +14,7 @@
 #include <linux/err.h>
 #include <linux/mutex.h>
 #include <linux/module.h>
+#include <linux/of.h>
 #include <linux/platform_device.h>
 #include <linux/regulator/consumer.h>
 #include <linux/regulator/userspace-consumer.h>
@@ -24,6 +25,7 @@ struct userspace_consumer_data {
 
 	struct mutex lock;
 	bool enabled;
+	bool no_autoswitch;
 
 	int num_supplies;
 	struct regulator_bulk_data *supplies;
@@ -96,19 +98,50 @@ static struct attribute *attributes[] = {
 	NULL,
 };
 
+static umode_t attr_visible(struct kobject *kobj, struct attribute *attr, int idx)
+{
+	struct device *dev = kobj_to_dev(kobj);
+	struct userspace_consumer_data *data = dev_get_drvdata(dev);
+
+	/* If a name hasn't been set, don't bother with the attribute */
+	if (attr == &dev_attr_name.attr && !data->name)
+		return 0;
+
+	return attr->mode;
+}
+
 static const struct attribute_group attr_group = {
 	.attrs	= attributes,
+	.is_visible =  attr_visible,
 };
 
 static int regulator_userspace_consumer_probe(struct platform_device *pdev)
 {
+	struct regulator_userspace_consumer_data tmpdata;
 	struct regulator_userspace_consumer_data *pdata;
 	struct userspace_consumer_data *drvdata;
 	int ret;
 
 	pdata = dev_get_platdata(&pdev->dev);
-	if (!pdata)
+	if (!pdata) {
+		if (!pdev->dev.of_node)
+			return -EINVAL;
+
+		pdata = &tmpdata;
+		memset(pdata, 0, sizeof(*pdata));
+
+		pdata->no_autoswitch = true;
+		pdata->num_supplies = 1;
+		pdata->supplies = devm_kzalloc(&pdev->dev, sizeof(*pdata->supplies), GFP_KERNEL);
+		if (!pdata->supplies)
+			return -ENOMEM;
+		pdata->supplies[0].supply = "vout";
+	}
+
+	if (pdata->num_supplies < 1) {
+		dev_err(&pdev->dev, "At least one supply required\n");
 		return -EINVAL;
+	}
 
 	drvdata = devm_kzalloc(&pdev->dev,
 			       sizeof(struct userspace_consumer_data),
@@ -119,21 +152,24 @@ static int regulator_userspace_consumer_probe(struct platform_device *pdev)
 	drvdata->name = pdata->name;
 	drvdata->num_supplies = pdata->num_supplies;
 	drvdata->supplies = pdata->supplies;
+	drvdata->no_autoswitch = pdata->no_autoswitch;
 
 	mutex_init(&drvdata->lock);
 
-	ret = devm_regulator_bulk_get(&pdev->dev, drvdata->num_supplies,
-				      drvdata->supplies);
+	ret = devm_regulator_bulk_get_exclusive(&pdev->dev, drvdata->num_supplies,
+						drvdata->supplies);
 	if (ret) {
 		dev_err(&pdev->dev, "Failed to get supplies: %d\n", ret);
 		return ret;
 	}
 
+	platform_set_drvdata(pdev, drvdata);
+
 	ret = sysfs_create_group(&pdev->dev.kobj, &attr_group);
 	if (ret != 0)
 		return ret;
 
-	if (pdata->init_on) {
+	if (pdata->init_on && !pdata->no_autoswitch) {
 		ret = regulator_bulk_enable(drvdata->num_supplies,
 					    drvdata->supplies);
 		if (ret) {
@@ -143,8 +179,12 @@ static int regulator_userspace_consumer_probe(struct platform_device *pdev)
 		}
 	}
 
-	drvdata->enabled = pdata->init_on;
-	platform_set_drvdata(pdev, drvdata);
+	ret = regulator_is_enabled(pdata->supplies[0].consumer);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "Failed to get regulator status\n");
+		goto err_enable;
+	}
+	drvdata->enabled = !!ret;
 
 	return 0;
 
@@ -160,17 +200,23 @@ static int regulator_userspace_consumer_remove(struct platform_device *pdev)
 
 	sysfs_remove_group(&pdev->dev.kobj, &attr_group);
 
-	if (data->enabled)
+	if (data->enabled && !data->no_autoswitch)
 		regulator_bulk_disable(data->num_supplies, data->supplies);
 
 	return 0;
 }
 
+static const struct of_device_id regulator_userspace_consumer_of_match[] = {
+	{ .compatible = "regulator-output", },
+	{},
+};
+
 static struct platform_driver regulator_userspace_consumer_driver = {
 	.probe		= regulator_userspace_consumer_probe,
 	.remove		= regulator_userspace_consumer_remove,
 	.driver		= {
 		.name		= "reg-userspace-consumer",
+		.of_match_table	= regulator_userspace_consumer_of_match,
 	},
 };
 
diff --git a/include/linux/regulator/userspace-consumer.h b/include/linux/regulator/userspace-consumer.h
index b5dba0628951..2249ee697f8b 100644
--- a/include/linux/regulator/userspace-consumer.h
+++ b/include/linux/regulator/userspace-consumer.h
@@ -21,6 +21,7 @@ struct regulator_userspace_consumer_data {
 	struct regulator_bulk_data *supplies;
 
 	bool init_on;
+	bool no_autoswitch;
 };
 
 #endif /* __REGULATOR_PLATFORM_CONSUMER_H_ */
-- 
2.38.1

Re: [PATCH v2 2/3] dt-bindings: regulator: Add regulator-output binding

[Rob Herring]

On Mon, 31 Oct 2022 16:37:03 -0700, Zev Weiss wrote:
> This describes a power output supplied by a regulator, such as a
> power outlet on a power distribution unit (PDU).
> 
> Signed-off-by: Zev Weiss <zev@bewilderbeest.net>
> ---
> 
> Changes since v1:
>  - removed 'regulator-leave-on' property
> 
>  .../bindings/regulator/regulator-output.yaml  | 39 +++++++++++++++++++
>  1 file changed, 39 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/regulator/regulator-output.yaml
> 

Reviewed-by: Rob Herring <robh@kernel.org>

Re: [PATCH v2 0/3] regulator: Add DT support for regulator-output connectors

[Mark Brown]

On Mon, 31 Oct 2022 16:37:01 -0700, Zev Weiss wrote:
> This is v2 of my recent series adding support for userspace-controlled
> regulator-supplied power outputs [2].  This is an important feature
> for some kinds of BMC (baseboard management controller) systems where
> the BMC provides an operator with manual control of a set of DC power
> outputs.
> 
> As in a broadly similar patchset that was recently almost merged [0],
> this takes the approach of providing support by extending the existing
> userspace-consumer regulator driver.  A couple questions about the
> userspace-consumer driver came up along the way, however.
> 
> [...]

Applied to

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/regulator.git for-next

Thanks!

[1/3] regulator: devres: Add devm_regulator_bulk_get_exclusive()
      commit: fd1845069711cdf1b1aaaa0f22311b7736396331
[2/3] dt-bindings: regulator: Add regulator-output binding
      commit: 14b8ad4c2580231fc45c2313ef822a15bb12f63f
[3/3] regulator: userspace-consumer: Handle regulator-output DT nodes
      commit: 5c51d4afcf3fd36159713556402e16cfab794ae9

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark