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>

diff --git a/drivers/hwmon/lm75.c b/drivers/hwmon/lm75.c
index a47ce32df98328ed5e1ba87f9bd16463f650be4d..845a0e09ea9fd0a8932f878ba07dd40ab4858788 100644 (file)
--- a/drivers/hwmon/lm75.c
+++ b/drivers/hwmon/lm75.c
@@ -123,7 +123,9 @@ 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
@@ -729,6 +731,7 @@ 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;
@@ -766,8 +769,18 @@ static int lm75_generic_probe(struct device *dev, const char *name,
                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;