On Monday 18 November 2019 18:11:47 Giovanni Mascellani wrote: > This patch exports standard hwmon pwmX_enable sysfs attribute for > enabling or disabling automatic fan control by BIOS. Standard value > "1" is for disabling automatic BIOS fan control and value "2" for > enabling. > > By default BIOS auto mode is enabled by laptop firmware. > > When BIOS auto mode is enabled, custom fan speed value (set via hwmon > pwmX sysfs attribute) is overwritten by SMM in few seconds and > therefore any custom settings are without effect. So this is reason > why implementing option for disabling BIOS auto mode is needed. > > So finally this patch allows kernel to set and control fan speed on > laptops, but it can be dangerous (like setting speed of other fans). > > The SMM commands to enable or disable automatic fan control are not > documented and are not the same on all Dell laptops. Therefore a > whitelist is used to send the correct codes only on laptopts for which > they are known. > > This patch was originally developed by Pali Rohár; later Giovanni > Mascellani implemented the whitelist. > > Signed-off-by: Giovanni Mascellani > Co-Developer-by: Pali Rohár This patch is fine for me now. I'm not sure if Co-Developer-by: tag is supported, but you can add: Signed-off-by: Pali Rohár > --- > drivers/hwmon/dell-smm-hwmon.c | 114 ++++++++++++++++++++++++++++++--- > 1 file changed, 104 insertions(+), 10 deletions(-) > > diff --git a/drivers/hwmon/dell-smm-hwmon.c b/drivers/hwmon/dell-smm-hwmon.c > index 4212d022d253..25d160b36a57 100644 > --- a/drivers/hwmon/dell-smm-hwmon.c > +++ b/drivers/hwmon/dell-smm-hwmon.c > @@ -68,6 +68,8 @@ static uint i8k_pwm_mult; > static uint i8k_fan_max = I8K_FAN_HIGH; > static bool disallow_fan_type_call; > static bool disallow_fan_support; > +static unsigned int manual_fan; > +static unsigned int auto_fan; > > #define I8K_HWMON_HAVE_TEMP1 (1 << 0) > #define I8K_HWMON_HAVE_TEMP2 (1 << 1) > @@ -300,6 +302,20 @@ static int i8k_get_fan_nominal_speed(int fan, int speed) > return i8k_smm(®s) ? : (regs.eax & 0xffff) * i8k_fan_mult; > } > > +/* > + * Enable or disable automatic BIOS fan control support > + */ > +static int i8k_enable_fan_auto_mode(bool enable) > +{ > + struct smm_regs regs = { }; > + > + if (disallow_fan_support) > + return -EINVAL; > + > + regs.eax = enable ? auto_fan : manual_fan; > + return i8k_smm(®s); > +} > + > /* > * Set the fan speed (off, low, high). Returns the new fan status. > */ > @@ -726,6 +742,35 @@ static ssize_t i8k_hwmon_pwm_store(struct device *dev, > return err < 0 ? -EIO : count; > } > > +static ssize_t i8k_hwmon_pwm_enable_store(struct device *dev, > + struct device_attribute *attr, > + const char *buf, size_t count) > +{ > + int err; > + bool enable; > + unsigned long val; > + > + if (!auto_fan) > + return -ENODEV; > + > + err = kstrtoul(buf, 10, &val); > + if (err) > + return err; > + > + if (val == 1) > + enable = false; > + else if (val == 2) > + enable = true; > + else > + return -EINVAL; > + > + mutex_lock(&i8k_mutex); > + err = i8k_enable_fan_auto_mode(enable); > + mutex_unlock(&i8k_mutex); > + > + return err ? err : count; > +} > + > static SENSOR_DEVICE_ATTR_RO(temp1_input, i8k_hwmon_temp, 0); > static SENSOR_DEVICE_ATTR_RO(temp1_label, i8k_hwmon_temp_label, 0); > static SENSOR_DEVICE_ATTR_RO(temp2_input, i8k_hwmon_temp, 1); > @@ -749,6 +794,7 @@ static SENSOR_DEVICE_ATTR_RO(temp10_label, i8k_hwmon_temp_label, 9); > static SENSOR_DEVICE_ATTR_RO(fan1_input, i8k_hwmon_fan, 0); > static SENSOR_DEVICE_ATTR_RO(fan1_label, i8k_hwmon_fan_label, 0); > static SENSOR_DEVICE_ATTR_RW(pwm1, i8k_hwmon_pwm, 0); > +static SENSOR_DEVICE_ATTR_WO(pwm1_enable, i8k_hwmon_pwm_enable, 0); > static SENSOR_DEVICE_ATTR_RO(fan2_input, i8k_hwmon_fan, 1); > static SENSOR_DEVICE_ATTR_RO(fan2_label, i8k_hwmon_fan_label, 1); > static SENSOR_DEVICE_ATTR_RW(pwm2, i8k_hwmon_pwm, 1); > @@ -780,12 +826,13 @@ static struct attribute *i8k_attrs[] = { > &sensor_dev_attr_fan1_input.dev_attr.attr, /* 20 */ > &sensor_dev_attr_fan1_label.dev_attr.attr, /* 21 */ > &sensor_dev_attr_pwm1.dev_attr.attr, /* 22 */ > - &sensor_dev_attr_fan2_input.dev_attr.attr, /* 23 */ > - &sensor_dev_attr_fan2_label.dev_attr.attr, /* 24 */ > - &sensor_dev_attr_pwm2.dev_attr.attr, /* 25 */ > - &sensor_dev_attr_fan3_input.dev_attr.attr, /* 26 */ > - &sensor_dev_attr_fan3_label.dev_attr.attr, /* 27 */ > - &sensor_dev_attr_pwm3.dev_attr.attr, /* 28 */ > + &sensor_dev_attr_pwm1_enable.dev_attr.attr, /* 23 */ > + &sensor_dev_attr_fan2_input.dev_attr.attr, /* 24 */ > + &sensor_dev_attr_fan2_label.dev_attr.attr, /* 25 */ > + &sensor_dev_attr_pwm2.dev_attr.attr, /* 26 */ > + &sensor_dev_attr_fan3_input.dev_attr.attr, /* 27 */ > + &sensor_dev_attr_fan3_label.dev_attr.attr, /* 28 */ > + &sensor_dev_attr_pwm3.dev_attr.attr, /* 29 */ > NULL > }; > > @@ -828,16 +875,19 @@ static umode_t i8k_is_visible(struct kobject *kobj, struct attribute *attr, > !(i8k_hwmon_flags & I8K_HWMON_HAVE_TEMP10)) > return 0; > > - if (index >= 20 && index <= 22 && > + if (index >= 20 && index <= 23 && > !(i8k_hwmon_flags & I8K_HWMON_HAVE_FAN1)) > return 0; > - if (index >= 23 && index <= 25 && > + if (index >= 24 && index <= 26 && > !(i8k_hwmon_flags & I8K_HWMON_HAVE_FAN2)) > return 0; > - if (index >= 26 && index <= 28 && > + if (index >= 27 && index <= 29 && > !(i8k_hwmon_flags & I8K_HWMON_HAVE_FAN3)) > return 0; > > + if (index == 23 && !auto_fan) > + return 0; > + > return attr->mode; > } > > @@ -1135,12 +1185,48 @@ static struct dmi_system_id i8k_blacklist_fan_support_dmi_table[] __initdata = { > { } > }; > > +struct i8k_fan_control_data { > + unsigned int manual_fan; > + unsigned int auto_fan; > +}; > + > +enum i8k_fan_controls { > + I8K_FAN_34A3_35A3, > +}; > + > +static const struct i8k_fan_control_data i8k_fan_control_data[] = { > + [I8K_FAN_34A3_35A3] = { > + .manual_fan = 0x34a3, > + .auto_fan = 0x35a3, > + }, > +}; > + > +static struct dmi_system_id i8k_whitelist_fan_control[] __initdata = { > + { > + .ident = "Dell Precision 5530", > + .matches = { > + DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."), > + DMI_EXACT_MATCH(DMI_PRODUCT_NAME, "Precision 5530"), > + }, > + .driver_data = (void *)&i8k_fan_control_data[I8K_FAN_34A3_35A3], > + }, > + { > + .ident = "Dell Latitude E6440", > + .matches = { > + DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."), > + DMI_EXACT_MATCH(DMI_PRODUCT_NAME, "Latitude E6440"), > + }, > + .driver_data = (void *)&i8k_fan_control_data[I8K_FAN_34A3_35A3], > + }, > + { } > +}; > + > /* > * Probe for the presence of a supported laptop. > */ > static int __init i8k_probe(void) > { > - const struct dmi_system_id *id; > + const struct dmi_system_id *id, *fan_control; > int fan, ret; > > /* > @@ -1200,6 +1286,14 @@ static int __init i8k_probe(void) > i8k_fan_max = fan_max ? : I8K_FAN_HIGH; /* Must not be 0 */ > i8k_pwm_mult = DIV_ROUND_UP(255, i8k_fan_max); > > + fan_control = dmi_first_match(i8k_whitelist_fan_control); > + if (fan_control && fan_control->driver_data) { > + const struct i8k_fan_control_data *fan_control_data = fan_control->driver_data; > + manual_fan = fan_control_data->manual_fan; > + auto_fan = fan_control_data->auto_fan; > + pr_info("enabling support for setting automatic/manual fan control\n"); > + } > + > if (!fan_mult) { > /* > * Autodetect fan multiplier based on nominal rpm -- Pali Rohár pali.rohar@gmail.com