[PATCH 4.19 072/338] hwmon: (pmbus) Add mutex to regulator ops

Greg Kroah-Hartman
2022-04-14T13:30:51Z

From: Patrick Rudolph <patrick.rudolph@9elements.com>

[ Upstream commit 686d303ee6301261b422ea51e64833d7909a2c36 ]

On PMBUS devices with multiple pages, the regulator ops need to be
protected with the update mutex. This prevents accidentally changing
the page in a separate thread while operating on the PMBUS_OPERATION
register.

Tested on Infineon xdpe11280 while a separate thread polls for sensor
data.

Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Signed-off-by: Marcello Sylvester Bauer <sylv@sylv.io>
Link: https://lore.kernel.org/r/b991506bcbf665f7af185945f70bf9d5cf04637c.1645804976.git.sylv@sylv.io
Fixes: ddbb4db4ced1b ("hwmon: (pmbus) Add regulator support")
Cc: Alan Tull <atull@opensource.altera.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/hwmon/pmbus/pmbus_core.c | 16 +++++++++++++---
1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/hwmon/pmbus/pmbus_core.c b/drivers/hwmon/pmbus/pmbus_core.c
index cd24b375df1e..d822aeab333d 100644
--- a/drivers/hwmon/pmbus/pmbus_core.c
+++ b/drivers/hwmon/pmbus/pmbus_core.c
@@ -2074,10 +2074,14 @@ static int pmbus_regulator_is_enabled(struct regulator_dev *rdev)
{
struct device *dev = rdev_get_dev(rdev);
struct i2c_client *client = to_i2c_client(dev->parent);
+ struct pmbus_data *data = i2c_get_clientdata(client);
u8 page = rdev_get_id(rdev);
int ret;

+ mutex_lock(&data->update_lock);
ret = pmbus_read_byte_data(client, page, PMBUS_OPERATION);
+ mutex_unlock(&data->update_lock);
+
if (ret < 0)
return ret;

@@ -2088,11 +2092,17 @@ static int _pmbus_regulator_on_off(struct regulator_dev *rdev, bool enable)
{
struct device *dev = rdev_get_dev(rdev);
struct i2c_client *client = to_i2c_client(dev->parent);
+ struct pmbus_data *data = i2c_get_clientdata(client);
u8 page = rdev_get_id(rdev);
+ int ret;

- return pmbus_update_byte_data(client, page, PMBUS_OPERATION,
- PB_OPERATION_CONTROL_ON,
- enable ? PB_OPERATION_CONTROL_ON : 0);
+ mutex_lock(&data->update_lock);
+ ret = pmbus_update_byte_data(client, page, PMBUS_OPERATION,
+ PB_OPERATION_CONTROL_ON,
+ enable ? PB_OPERATION_CONTROL_ON : 0);
+ mutex_unlock(&data->update_lock);
+
+ return ret;
}

static int pmbus_regulator_enable(struct regulator_dev *rdev)
--
2.34.1