linux-kernel - [PATCH v3 1/5] regulator: Allow regulators to verify enabled during enable()

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Thu, 28 May 2020 21:16:21 +0530
From:   Sumit Semwal <sumit.semwal@...aro.org>
To:     agross@...nel.org, bjorn.andersson@...aro.org, lgirdwood@...il.com,
        broonie@...nel.org, robh+dt@...nel.org
Cc:     nishakumari@...eaurora.org, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        kgunda@...eaurora.org, rnayak@...eaurora.org,
        Sumit Semwal <sumit.semwal@...aro.org>
Subject: [PATCH v3 1/5] regulator: Allow regulators to verify enabled during enable()

Some regulators might need to verify that they have indeed been enabled
after the enable() call is made and enable_time delay has passed.

This is implemented by repeatedly checking is_enabled() upto
poll_enabled_time, waiting for the already calculated enable delay in
each iteration.

Signed-off-by: Sumit Semwal <sumit.semwal@...aro.org>
---
 drivers/regulator/core.c         | 28 ++++++++++++++++++++++++++++
 include/linux/regulator/driver.h |  5 +++++
 2 files changed, 33 insertions(+)

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index 7486f6e4e613..06199f182114 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -2409,6 +2409,34 @@ static int _regulator_do_enable(struct regulator_dev *rdev)
 
 	_regulator_enable_delay(delay);
 
+	/* If set, poll upto poll_enabled_time uS to see if the regulator
+	 * actually got enabled.
+	 * For each iteration, wait for the enable_time delay calculated
+	 * above already.
+	 * If the regulator isn't enabled after poll_enabled_time has
+	 * expired, return -ETIMEDOUT.
+	 */
+	if (rdev->desc->poll_enabled_time) {
+		unsigned int time_remaining = rdev->desc->poll_enabled_time;
+
+		while (time_remaining > 0) {
+			/* We've already waited for enable_time above;
+			 * so we can start with immediate check of the
+			 * status of the regulator.
+			 */
+			if (rdev->desc->ops->is_enabled(rdev))
+				break;
+
+			_regulator_enable_delay(delay);
+			time_remaining -= delay;
+		}
+
+		if (time_remaining <= 0) {
+			rdev_err(rdev, "Enabled check failed.\n");
+			return -ETIMEDOUT;
+		}
+	}
+
 	trace_regulator_enable_complete(rdev_get_name(rdev));
 
 	return 0;
diff --git a/include/linux/regulator/driver.h b/include/linux/regulator/driver.h
index 29d920516e0b..bb50e943010f 100644
--- a/include/linux/regulator/driver.h
+++ b/include/linux/regulator/driver.h
@@ -322,6 +322,9 @@ enum regulator_type {
  * @enable_time: Time taken for initial enable of regulator (in uS).
  * @off_on_delay: guard time (in uS), before re-enabling a regulator
  *
+ * @poll_enabled_time: Maximum time (in uS) to poll if the regulator is
+ *                          actually enabled, after enable() call
+ *
  * @of_map_mode: Maps a hardware mode defined in a DeviceTree to a standard mode
  */
 struct regulator_desc {
@@ -389,6 +392,8 @@ struct regulator_desc {
 
 	unsigned int off_on_delay;
 
+	unsigned int poll_enabled_time;
+
 	unsigned int (*of_map_mode)(unsigned int mode);
 };
 
-- 
2.26.2