linux-kernel - [PATCH] regulator: core: Limit propagation of parent voltage count and list

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Date:   Fri, 24 Mar 2017 13:09:52 -0700
From:   Matthias Kaehlcke <mka@...omium.org>
To:     Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Javier Martinez Canillas <javier@....samsung.com>
Cc:     linux-kernel@...r.kernel.org,
        Douglas Anderson <dianders@...omium.org>,
        Brian Norris <briannorris@...omium.org>,
        Matthias Kaehlcke <mka@...omium.org>
Subject: [PATCH] regulator: core: Limit propagation of parent voltage count and list

Commit 26988efe11b1 ("regulator: core: Allow to get voltage count and
list from parent") introduces the propagation of the parent voltage
count and list for regulators that don't provide this information
themselves. The goal is to support simple switch regulators, however as
a side effect normal continuous regulators can leak details of their
supplies and provide consumers with inconsistent information.

Limit the propagation of the voltage count and list to regulators which
don't have get_voltage(_sel) and list_voltage ops.

Signed-off-by: Matthias Kaehlcke <mka@...omium.org>
---
 drivers/regulator/core.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index 53d4fc70dbd0..121838e0125b 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -2487,6 +2487,10 @@ static int _regulator_list_voltage(struct regulator *regulator,
 		if (lock)
 			mutex_unlock(&rdev->mutex);
 	} else if (rdev->supply) {
+		// Limit propagation of parent values to switch regulators
+		if (ops->get_voltage || ops->get_voltage_sel)
+			return -EINVAL;
+
 		ret = _regulator_list_voltage(rdev->supply, selector, lock);
 	} else {
 		return -EINVAL;
@@ -2540,6 +2544,7 @@ EXPORT_SYMBOL_GPL(regulator_is_enabled);
 int regulator_count_voltages(struct regulator *regulator)
 {
 	struct regulator_dev	*rdev = regulator->rdev;
+	const struct regulator_ops *ops = rdev->desc->ops;
 
 	if (rdev->desc->n_voltages)
 		return rdev->desc->n_voltages;
@@ -2547,6 +2552,10 @@ int regulator_count_voltages(struct regulator *regulator)
 	if (!rdev->supply)
 		return -EINVAL;
 
+	// Limit propagation of parent value to switch regulators
+	if (ops->get_voltage || ops->get_voltage_sel || ops->list_voltage)
+		return -EINVAL;
+
 	return regulator_count_voltages(rdev->supply);
 }
 EXPORT_SYMBOL_GPL(regulator_count_voltages);
-- 
2.12.1.578.ge9c3154ca4-goog