hwmon: (lm63) expose PWM frequency and LUT hysteresis as writable

The driver caches the PWM frequency register and the CONFIG_FAN slow-clock
select bit, but never lets userspace pick a different output frequency.
Add a pwm1_freq sysfs attribute that selects the closest SCS + PFR
combination for the requested value in Hz, gated by manual mode like
set_pwm1(). PFR is clamped to 31 so that 2*PFR fits in the chip's 6-bit
PWM register (matching the existing scaling assumption in show_pwm1).

The hardware LUT hysteresis register is shared by all LUT entries, so
the per-point pwm1_auto_pointN_temp_hyst attributes can't be made RW
without N-to-1 cross-attribute side effects. Following the max31760
precedent, expose a single chip-wide pwm1_auto_point_temp_hyst attribute
holding the hysteresis amount in millidegrees; the per-point attributes
stay RO and continue to show the resulting absolute trip-down
temperature for each entry.

This was tested on a Linksys LGS328MPC switch hardware where the fan
would not spin with the default PWM Frequency, which is why this change
is required.

Signed-off-by: Jan-Henrik Bruhn <kernel@jhbruhn.de>
Link: https://lore.kernel.org/r/20260523133617.3439102-1-kernel@jhbruhn.de
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

diff --git a/drivers/hwmon/lm63.c b/drivers/hwmon/lm63.c
index a0d77a7386a9de9fa2a62b1c749962c71cc16a03..e2a429e579ac1b2afa8c7cdbc2cc30e0b6d21d91 100644 (file)
--- a/drivers/hwmon/lm63.c
+++ b/drivers/hwmon/lm63.c
@@ -92,6 +92,9 @@ static const unsigned short normal_i2c[] = { 0x18, 0x4c, 0x4e, I2C_CLIENT_END };
 #define LM96163_REG_REMOTE_TEMP_U_LSB  0x32
 #define LM96163_REG_CONFIG_ENHANCED    0x45
 
+#define LM63_PWM_BASE_FAST_HZ          180000
+#define LM63_PWM_BASE_SLOW_HZ          700
+
 #define LM63_MAX_CONVRATE              9
 
 #define LM63_MAX_CONVRATE_HZ           32
@@ -455,6 +458,91 @@ static ssize_t pwm1_enable_store(struct device *dev,
        return count;
 }
 
+static ssize_t pwm1_freq_show(struct device *dev,
+                             struct device_attribute *dummy, char *buf)
+{
+       struct lm63_data *data = lm63_update_device(dev);
+       unsigned int base, freq;
+
+       mutex_lock(&data->update_lock);
+       base = (data->config_fan & 0x08) ?
+              LM63_PWM_BASE_SLOW_HZ : LM63_PWM_BASE_FAST_HZ;
+       freq = data->pwm1_freq;
+       mutex_unlock(&data->update_lock);
+
+       return sprintf(buf, "%u\n", base / freq);
+}
+
+/*
+ * Pick the closest CONFIG_FAN.SCS + PFR for the requested frequency.
+ * PWM_FREQ writes need the LUT unlocked, same as set_pwm1(). LUT PWM
+ * bytes are register-relative; rewrite them after a frequency change
+ * if duty cycles must be preserved.
+ */
+static ssize_t pwm1_freq_store(struct device *dev,
+                              struct device_attribute *dummy,
+                              const char *buf, size_t count)
+{
+       struct lm63_data *data = dev_get_drvdata(dev);
+       struct i2c_client *client = data->client;
+       unsigned long val, pfr_fast, pfr_slow, err_fast, err_slow, pfr;
+       bool slow_clock;
+       int ret;
+
+       ret = kstrtoul(buf, 10, &val);
+       if (ret)
+               return ret;
+       if (val == 0)
+               return -EINVAL;
+
+       pfr_fast = clamp_val(DIV_ROUND_CLOSEST((unsigned long)LM63_PWM_BASE_FAST_HZ, val),
+                            1UL, 31UL);
+       pfr_slow = clamp_val(DIV_ROUND_CLOSEST((unsigned long)LM63_PWM_BASE_SLOW_HZ, val),
+                            1UL, 31UL);
+       err_fast = abs_diff(LM63_PWM_BASE_FAST_HZ / pfr_fast, val);
+       err_slow = abs_diff(LM63_PWM_BASE_SLOW_HZ / pfr_slow, val);
+
+       if (err_slow < err_fast) {
+               slow_clock = true;
+               pfr = pfr_slow;
+       } else {
+               slow_clock = false;
+               pfr = pfr_fast;
+       }
+
+       mutex_lock(&data->update_lock);
+       ret = i2c_smbus_read_byte_data(client, LM63_REG_CONFIG_FAN);
+       if (ret < 0) {
+               mutex_unlock(&data->update_lock);
+               return ret;
+       }
+       data->config_fan = ret;
+
+       if (!(data->config_fan & 0x20)) { /* register is read-only */
+               mutex_unlock(&data->update_lock);
+               return -EPERM;
+       }
+
+       if (data->kind == lm96163) {
+               ret = i2c_smbus_read_byte_data(client, LM96163_REG_CONFIG_ENHANCED);
+               if (ret < 0) {
+                       mutex_unlock(&data->update_lock);
+                       return ret;
+               }
+               data->pwm_highres = !slow_clock && pfr == 8 && (ret & 0x10);
+       }
+
+       if (slow_clock)
+               data->config_fan |= 0x08;
+       else
+               data->config_fan &= ~0x08;
+       i2c_smbus_write_byte_data(client, LM63_REG_CONFIG_FAN, data->config_fan);
+       i2c_smbus_write_byte_data(client, LM63_REG_PWM_FREQ, pfr);
+       data->pwm1_freq = pfr;
+       mutex_unlock(&data->update_lock);
+       return count;
+}
+
 /*
  * There are 8bit registers for both local(temp1) and remote(temp2) sensor.
  * For remote sensor registers temp2_offset has to be considered,
@@ -629,6 +717,47 @@ static ssize_t show_lut_temp_hyst(struct device *dev,
        return sprintf(buf, "%d\n", temp);
 }
 
+/*
+ * The LM63 has a single hysteresis register shared by all LUT entries.
+ * Expose it as a chip-wide hysteresis amount in millidegrees; the
+ * per-point pwm1_auto_pointN_temp_hyst attributes remain read-only and
+ * show the resulting absolute trip-down temperature for each entry.
+ */
+static ssize_t pwm1_auto_point_temp_hyst_show(struct device *dev,
+                                             struct device_attribute *dummy,
+                                             char *buf)
+{
+       struct lm63_data *data = lm63_update_device(dev);
+       u8 hyst;
+
+       mutex_lock(&data->update_lock);
+       hyst = data->lut_temp_hyst;
+       mutex_unlock(&data->update_lock);
+
+       return sprintf(buf, "%d\n", TEMP8_FROM_REG(hyst));
+}
+
+static ssize_t pwm1_auto_point_temp_hyst_store(struct device *dev,
+                                              struct device_attribute *dummy,
+                                              const char *buf, size_t count)
+{
+       struct lm63_data *data = dev_get_drvdata(dev);
+       struct i2c_client *client = data->client;
+       unsigned long val;
+       int err;
+
+       err = kstrtoul(buf, 10, &val);
+       if (err)
+               return err;
+
+       mutex_lock(&data->update_lock);
+       data->lut_temp_hyst = HYST_TO_REG(val);
+       i2c_smbus_write_byte_data(client, LM63_REG_LUT_TEMP_HYST,
+                                 data->lut_temp_hyst);
+       mutex_unlock(&data->update_lock);
+       return count;
+}
+
 /*
  * And now the other way around, user-space provides an absolute
  * hysteresis value and we have to store a relative one
@@ -764,6 +893,8 @@ static SENSOR_DEVICE_ATTR(fan1_min, S_IWUSR | S_IRUGO, show_fan,
 
 static SENSOR_DEVICE_ATTR(pwm1, S_IWUSR | S_IRUGO, show_pwm1, set_pwm1, 0);
 static DEVICE_ATTR_RW(pwm1_enable);
+static DEVICE_ATTR_RW(pwm1_freq);
+static DEVICE_ATTR_RW(pwm1_auto_point_temp_hyst);
 static SENSOR_DEVICE_ATTR(pwm1_auto_point1_pwm, S_IWUSR | S_IRUGO,
        show_pwm1, set_pwm1, 1);
 static SENSOR_DEVICE_ATTR(pwm1_auto_point1_temp, S_IWUSR | S_IRUGO,
@@ -869,6 +1000,8 @@ static DEVICE_ATTR_RW(update_interval);
 static struct attribute *lm63_attributes[] = {
        &sensor_dev_attr_pwm1.dev_attr.attr,
        &dev_attr_pwm1_enable.attr,
+       &dev_attr_pwm1_freq.attr,
+       &dev_attr_pwm1_auto_point_temp_hyst.attr,
        &sensor_dev_attr_pwm1_auto_point1_pwm.dev_attr.attr,
        &sensor_dev_attr_pwm1_auto_point1_temp.dev_attr.attr,
        &sensor_dev_attr_pwm1_auto_point1_temp_hyst.dev_attr.attr,