compatible = "microchip,tcn75";
reg = <0x48>;
#thermal-sensor-cells = <0>;
- alert-polarity-active-high;
+ ti,alert-polarity-active-high;
};
eeprom@50 {
--- /dev/null
+From ccef20232ded30ca6e73865458ebe89c0fe48dfe Mon Sep 17 00:00:00 2001
+From: Markus Stockhausen <markus.stockhausen@gmx.de>
+Date: Sat, 2 May 2026 19:32:07 +0200
+Subject: hwmon: (lm75) Fix configuration register writes.
+
+Sensors configurations are defined by set and clear masks. These
+do not follow a consistent "clear mask is a superset of set mask"
+rule. This relaxed definition breaks lm75_write_config()
+
+static inline int lm75_write_config(struct lm75_data *data, u16 set_mask,
+ u16 clr_mask)
+{
+ return regmap_update_bits(data->regmap, LM75_REG_CONF,
+ clr_mask | LM75_SHUTDOWN, set_mask);
+}
+
+Basically all bits from set_mask that are not defined in clr_mask are
+dropped. Fix that by enhancing the helper to always combine clr_mask
+and set_mask into the mask bits of regmap_update_bits().
+
+Fixes: 6da24a25f766 ("hwmon: (lm75) Hide register size differences in regmap access functions")
+Suggested-by: Guenter Roeck <linux@roeck-us.net>
+Signed-off-by: Markus Stockhausen <markus.stockhausen@gmx.de>
+Link: https://lore.kernel.org/r/20260502173207.3567876-3-markus.stockhausen@gmx.de
+Signed-off-by: Guenter Roeck <linux@roeck-us.net>
+---
+ drivers/hwmon/lm75.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+--- a/drivers/hwmon/lm75.c
++++ b/drivers/hwmon/lm75.c
+@@ -352,7 +352,7 @@ static inline int lm75_write_config(stru
+ u16 clr_mask)
+ {
+ return regmap_update_bits(data->regmap, LM75_REG_CONF,
+- clr_mask | LM75_SHUTDOWN, set_mask);
++ clr_mask | set_mask | LM75_SHUTDOWN, set_mask);
+ }
+
+ static irqreturn_t lm75_alarm_handler(int irq, void *private)
--- /dev/null
+From da96d42a568b98508729abf5c8f05d6e7770443d Mon Sep 17 00:00:00 2001
+From: Markus Stockhausen <markus.stockhausen@gmx.de>
+Date: Mon, 4 May 2026 17:10:20 +0200
+Subject: hwmon: (lm75) Support active-high alert polarity
+
+LM75 devices supported by this driver support configurable active-high
+alert polarity. This is already documented in the devicetree description.
+Add support for it to the driver.
+
+Follow documentation and defensively enforce active-low if property is
+not set. This avoids possible inconsistencies for future devices with
+wrong parametrization. No API breakage as all current devices have
+their parameters set to active-low.
+
+Signed-off-by: Markus Stockhausen <markus.stockhausen@gmx.de>
+Link: https://lore.kernel.org/r/20260504151020.462342-3-markus.stockhausen@gmx.de
+Signed-off-by: Guenter Roeck <linux@roeck-us.net>
+---
+ drivers/hwmon/lm75.c | 19 ++++++++++++++++---
+ 1 file changed, 16 insertions(+), 3 deletions(-)
+
+--- a/drivers/hwmon/lm75.c
++++ b/drivers/hwmon/lm75.c
+@@ -122,7 +122,9 @@ struct lm75_data {
+
+ static const u8 lm75_sample_set_masks[] = { 0 << 5, 1 << 5, 2 << 5, 3 << 5 };
+
+-#define LM75_SAMPLE_CLEAR_MASK (3 << 5)
++#define LM75_ALERT_POLARITY_HIGH_8_BIT (BIT(2))
++#define LM75_ALERT_POLARITY_HIGH_16_BIT (BIT(2) << 8)
++#define LM75_SAMPLE_CLEAR_MASK (3 << 5)
+
+ /* The structure below stores the configuration values of the supported devices.
+ * In case of being supported multiple configurations, the default one must
+@@ -710,6 +712,7 @@ static void lm75_remove(void *data)
+ static int lm75_generic_probe(struct device *dev, const char *name,
+ enum lm75_type kind, int irq, struct regmap *regmap)
+ {
++ u16 clr_mask, pol_mask, set_mask;
+ struct device *hwmon_dev;
+ struct lm75_data *data;
+ int status, err;
+@@ -744,8 +747,18 @@ static int lm75_generic_probe(struct dev
+ return err;
+ data->orig_conf = status;
+
+- err = lm75_write_config(data, data->params->set_mask,
+- data->params->clr_mask);
++ /* Enforce polarity active-low (default) or active-high (devicetree) */
++ if (!data->params->config_reg_16bits)
++ pol_mask = LM75_ALERT_POLARITY_HIGH_8_BIT;
++ else
++ pol_mask = LM75_ALERT_POLARITY_HIGH_16_BIT;
++
++ clr_mask = data->params->clr_mask | pol_mask;
++ set_mask = data->params->set_mask & ~pol_mask;
++ if (device_property_read_bool(dev, "ti,alert-polarity-active-high"))
++ set_mask |= pol_mask;
++
++ err = lm75_write_config(data, set_mask, clr_mask);
+ if (err)
+ return err;
+
+++ /dev/null
-From 92ea53e058d40ebda7326016494e3c21dc536c53 Mon Sep 17 00:00:00 2001
-From: Markus Stockhausen <markus.stockhausen@gmx.de>
-Date: Mon, 23 Mar 2026 22:12:01 +0200
-Subject: [PATCH] hwmon: lm75 alert polarity swap
-
-The LM75 can steer the alert polarity. In default mode the alert
-output pin is active-low. This can not be configured with the
-existing LM75 driver.
-
-There are hardware designs that use this alert output for an automatic
-fan speed control. E.g. the D-Link DGS-1250. This works as follows
-
-- temperature below Tmax threshold -> alert pin low -> fan slow speed
-- temperature above Tmax threshold -> alert pin high -> fan high speed
-
-As one can see the hardware design requires the alert pin to be
-configured in mode active-high to work as described. Add a LM75 DTS
-property "alert-polarity-active-high" that allows to swap the alert
-pin behaviour during initialization to active-high.
-
-Signed-off-by: Markus Stockhausen <markus.stockhausen@gmx.de>
-
---- a/drivers/hwmon/lm75.c
-+++ b/drivers/hwmon/lm75.c
-@@ -122,7 +122,8 @@ struct lm75_data {
-
- static const u8 lm75_sample_set_masks[] = { 0 << 5, 1 << 5, 2 << 5, 3 << 5 };
-
--#define LM75_SAMPLE_CLEAR_MASK (3 << 5)
-+#define LM75_SAMPLE_CLEAR_MASK (3 << 5)
-+#define LM75_ALERT_POLARITY_HIGH BIT(2)
-
- /* The structure below stores the configuration values of the supported devices.
- * In case of being supported multiple configurations, the default one must
-@@ -713,6 +714,7 @@ static int lm75_generic_probe(struct dev
- struct device *hwmon_dev;
- struct lm75_data *data;
- int status, err;
-+ u16 set_mask;
-
- data = devm_kzalloc(dev, sizeof(struct lm75_data), GFP_KERNEL);
- if (!data)
-@@ -744,8 +746,13 @@ static int lm75_generic_probe(struct dev
- return err;
- data->orig_conf = status;
-
-- err = lm75_write_config(data, data->params->set_mask,
-- data->params->clr_mask);
-+ set_mask = data->params->set_mask;
-+ if (of_property_read_bool(dev->of_node, "alert-polarity-active-high")) {
-+ pr_info("set lm75 alert to active high\n");
-+ set_mask |= LM75_ALERT_POLARITY_HIGH;
-+ }
-+
-+ err = lm75_write_config(data, set_mask, data->params->clr_mask);
- if (err)
- return err;
-
projects / thirdparty / openwrt.git / commitdiff
