drm/nouveau/pm: manual pwm fanspeed management for nv40+ boards

Exposes the following sysfs entries:
- fan0_input: read the rotational speed of the fan (poll a bit during 250ms)
- pwm0: set the pwm duty cycle
- pwm0_min/max: set the minimum/maximum pwm value

v2 (Ben Skeggs):
- nv50 pwm controller code removed in favour of other more complete code
- FAN_RPM -> FAN_SENSE
- merged FAN_SENSE readout into common code, not at all nv50-specific
- protected fanspeed changes with perflvl_wr
- formatting tidying
- added some comments where things are shaky

v3 (Martin Peres)
- ensure duty min/max from thermal table are sane

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Signed-off-by: Martin Peres <martin.peres@ensi-bourges.fr>

drivers/gpu/drm/nouveau/nouveau_bios.h

@@ -58,6 +58,8 @@ struct dcb_i2c_entry {
 enum dcb_gpio_tag {
 	DCB_GPIO_TVDAC0 = 0xc,
 	DCB_GPIO_TVDAC1 = 0x2d,
+	DCB_GPIO_PWM_FAN = 0x9,
+	DCB_GPIO_FAN_SENSE = 0x3d,
 };
 
 struct dcb_gpio_entry {

drivers/gpu/drm/nouveau/nouveau_drv.h

@@ -521,13 +521,19 @@ struct nouveau_pm_memtimings {
 	int nr_timing;
 };
 
+struct nouveau_pm_fan {
+	u32 min_duty;
+	u32 max_duty;
+};
+
 struct nouveau_pm_engine {
 	struct nouveau_pm_voltage voltage;
 	struct nouveau_pm_level perflvl[NOUVEAU_PM_MAX_LEVEL];
 	int nr_perflvl;
 	struct nouveau_pm_memtimings memtimings;
 	struct nouveau_pm_temp_sensor_constants sensor_constants;
 	struct nouveau_pm_threshold_temp threshold_temp;
+	struct nouveau_pm_fan fan;
 	u32 pwm_divisor;
 
 	struct nouveau_pm_level boot;

drivers/gpu/drm/nouveau/nouveau_pm.c

@@ -64,6 +64,10 @@ nouveau_pm_perflvl_set(struct drm_device *dev, struct nouveau_pm_level *perflvl)
 	if (perflvl == pm->cur)
 		return 0;
 
+	/*XXX: not on all boards, we should control based on temperature
+	 *     on recent boards..  or maybe on some other factor we don't
+	 *     know about?
+	 */
 	if (pm->fanspeed_set && perflvl->fanspeed) {
 		ret = pm->fanspeed_set(dev, perflvl->fanspeed);
 		if (ret)
@@ -424,6 +428,176 @@ static SENSOR_DEVICE_ATTR(update_rate, S_IRUGO,
 						nouveau_hwmon_show_update_rate,
 						NULL, 0);
 
+static ssize_t
+nouveau_hwmon_show_fan0_input(struct device *d, struct device_attribute *attr,
+			      char *buf)
+{
+	struct drm_device *dev = dev_get_drvdata(d);
+	struct drm_nouveau_private *dev_priv = dev->dev_private;
+	struct nouveau_timer_engine *ptimer = &dev_priv->engine.timer;
+	struct nouveau_gpio_engine *pgpio = &dev_priv->engine.gpio;
+	struct dcb_gpio_entry *gpio;
+	u32 cycles, cur, prev;
+	u64 start;
+
+	gpio = nouveau_bios_gpio_entry(dev, DCB_GPIO_FAN_SENSE);
+	if (!gpio)
+		return -ENODEV;
+
+	/* Monitor the GPIO input 0x3b for 250ms.
+	 * When the fan spins, it changes the value of GPIO FAN_SENSE.
+	 * We get 4 changes (0 -> 1 -> 0 -> 1 -> [...]) per complete rotation.
+	 */
+	start = ptimer->read(dev);
+	prev = pgpio->get(dev, DCB_GPIO_FAN_SENSE);
+	cycles = 0;
+	do {
+		cur = pgpio->get(dev, DCB_GPIO_FAN_SENSE);
+		if (prev != cur) {
+			cycles++;
+			prev = cur;
+		}
+
+		usleep_range(500, 1000); /* supports 0 < rpm < 7500 */
+	} while (ptimer->read(dev) - start < 250000000);
+
+	/* interpolate to get rpm */
+	return sprintf(buf, "%i\n", cycles / 4 * 4 * 60);
+}
+static SENSOR_DEVICE_ATTR(fan0_input, S_IRUGO, nouveau_hwmon_show_fan0_input,
+			  NULL, 0);
+
+static ssize_t
+nouveau_hwmon_get_pwm0(struct device *d, struct device_attribute *a, char *buf)
+{
+	struct drm_device *dev = dev_get_drvdata(d);
+	struct drm_nouveau_private *dev_priv = dev->dev_private;
+	struct nouveau_pm_engine *pm = &dev_priv->engine.pm;
+	int ret = -ENODEV;
+
+	if (pm->fanspeed_get)
+		ret = pm->fanspeed_get(dev);
+	if (ret < 0)
+		return ret;
+
+	return sprintf(buf, "%i\n", ret);
+}
+
+static ssize_t
+nouveau_hwmon_set_pwm0(struct device *d, struct device_attribute *a,
+		       const char *buf, size_t count)
+{
+	struct drm_device *dev = dev_get_drvdata(d);
+	struct drm_nouveau_private *dev_priv = dev->dev_private;
+	struct nouveau_pm_engine *pm = &dev_priv->engine.pm;
+	int ret = -ENODEV;
+	long value;
+
+	if (nouveau_perflvl_wr != 7777)
+		return -EPERM;
+
+	if (strict_strtol(buf, 10, &value) == -EINVAL)
+		return -EINVAL;
+
+	if (value < pm->fan.min_duty)
+		value = pm->fan.min_duty;
+	if (value > pm->fan.max_duty)
+		value = pm->fan.max_duty;
+
+	if (pm->fanspeed_set)
+		ret = pm->fanspeed_set(dev, value);
+	if (ret)
+		return ret;
+
+	return count;
+}
+
+static SENSOR_DEVICE_ATTR(pwm0, S_IRUGO | S_IWUSR,
+			  nouveau_hwmon_get_pwm0,
+			  nouveau_hwmon_set_pwm0, 0);
+
+static ssize_t
+nouveau_hwmon_get_pwm0_min(struct device *d,
+			   struct device_attribute *a, char *buf)
+{
+	struct drm_device *dev = dev_get_drvdata(d);
+	struct drm_nouveau_private *dev_priv = dev->dev_private;
+	struct nouveau_pm_engine *pm = &dev_priv->engine.pm;
+
+	return sprintf(buf, "%i\n", pm->fan.min_duty);
+}
+
+static ssize_t
+nouveau_hwmon_set_pwm0_min(struct device *d, struct device_attribute *a,
+			   const char *buf, size_t count)
+{
+	struct drm_device *dev = dev_get_drvdata(d);
+	struct drm_nouveau_private *dev_priv = dev->dev_private;
+	struct nouveau_pm_engine *pm = &dev_priv->engine.pm;
+	long value;
+
+	if (strict_strtol(buf, 10, &value) == -EINVAL)
+		return -EINVAL;
+
+	if (value < 0)
+		value = 0;
+
+	if (pm->fan.max_duty - value < 10)
+		value = pm->fan.max_duty - 10;
+
+	if (value < 10)
+		pm->fan.min_duty = 10;
+	else
+		pm->fan.min_duty = value;
+
+	return count;
+}
+
+static SENSOR_DEVICE_ATTR(pwm0_min, S_IRUGO | S_IWUSR,
+			  nouveau_hwmon_get_pwm0_min,
+			  nouveau_hwmon_set_pwm0_min, 0);
+
+static ssize_t
+nouveau_hwmon_get_pwm0_max(struct device *d,
+			   struct device_attribute *a, char *buf)
+{
+	struct drm_device *dev = dev_get_drvdata(d);
+	struct drm_nouveau_private *dev_priv = dev->dev_private;
+	struct nouveau_pm_engine *pm = &dev_priv->engine.pm;
+
+	return sprintf(buf, "%i\n", pm->fan.max_duty);
+}
+
+static ssize_t
+nouveau_hwmon_set_pwm0_max(struct device *d, struct device_attribute *a,
+			   const char *buf, size_t count)
+{
+	struct drm_device *dev = dev_get_drvdata(d);
+	struct drm_nouveau_private *dev_priv = dev->dev_private;
+	struct nouveau_pm_engine *pm = &dev_priv->engine.pm;
+	long value;
+
+	if (strict_strtol(buf, 10, &value) == -EINVAL)
+		return -EINVAL;
+
+	if (value < 0)
+		value = 0;
+
+	if (value - pm->fan.min_duty < 10)
+		value = pm->fan.min_duty + 10;
+
+	if (value > 100)
+		pm->fan.max_duty = 100;
+	else
+		pm->fan.max_duty = value;
+
+	return count;
+}
+
+static SENSOR_DEVICE_ATTR(pwm0_max, S_IRUGO | S_IWUSR,
+			  nouveau_hwmon_get_pwm0_max,
+			  nouveau_hwmon_set_pwm0_max, 0);
+
 static struct attribute *hwmon_attributes[] = {
 	&sensor_dev_attr_temp1_input.dev_attr.attr,
 	&sensor_dev_attr_temp1_max.dev_attr.attr,
@@ -432,10 +606,26 @@ static struct attribute *hwmon_attributes[] = {
 	&sensor_dev_attr_update_rate.dev_attr.attr,
 	NULL
 };
+static struct attribute *hwmon_fan_rpm_attributes[] = {
+	&sensor_dev_attr_fan0_input.dev_attr.attr,
+	NULL
+};
+static struct attribute *hwmon_pwm_fan_attributes[] = {
+	&sensor_dev_attr_pwm0.dev_attr.attr,
+	&sensor_dev_attr_pwm0_min.dev_attr.attr,
+	&sensor_dev_attr_pwm0_max.dev_attr.attr,
+	NULL
+};
 
 static const struct attribute_group hwmon_attrgroup = {
 	.attrs = hwmon_attributes,
 };
+static const struct attribute_group hwmon_fan_rpm_attrgroup = {
+	.attrs = hwmon_fan_rpm_attributes,
+};
+static const struct attribute_group hwmon_pwm_fan_attrgroup = {
+	.attrs = hwmon_pwm_fan_attributes,
+};
 #endif
 
 static int
@@ -445,7 +635,7 @@ nouveau_hwmon_init(struct drm_device *dev)
 	struct drm_nouveau_private *dev_priv = dev->dev_private;
 	struct nouveau_pm_engine *pm = &dev_priv->engine.pm;
 	struct device *hwmon_dev;
-	int ret;
+	int ret = 0;
 
 	if (!pm->temp_get)
 		return -ENODEV;
@@ -458,17 +648,46 @@ nouveau_hwmon_init(struct drm_device *dev)
 		return ret;
 	}
 	dev_set_drvdata(hwmon_dev, dev);
+
+	/* default sysfs entries */
 	ret = sysfs_create_group(&dev->pdev->dev.kobj, &hwmon_attrgroup);
 	if (ret) {
-		NV_ERROR(dev,
-			"Unable to create hwmon sysfs file: %d\n", ret);
-		hwmon_device_unregister(hwmon_dev);
-		return ret;
+		if (ret)
+			goto error;
+	}
+
+	/* if the card has a pwm fan */
+	/*XXX: incorrect, need better detection for this, some boards have
+	 *     the gpio entries for pwm fan control even when there's no
+	 *     actual fan connected to it... therm table? */
+	if (pm->fanspeed_get && pm->fanspeed_get(dev) >= 0) {
+		ret = sysfs_create_group(&dev->pdev->dev.kobj,
+					 &hwmon_pwm_fan_attrgroup);
+		if (ret)
+			goto error;
+	}
+
+	/* if the card can read the fan rpm */
+	if (nouveau_bios_gpio_entry(dev, DCB_GPIO_FAN_SENSE)) {
+		ret = sysfs_create_group(&dev->pdev->dev.kobj,
+					 &hwmon_fan_rpm_attrgroup);
+		if (ret)
+			goto error;
 	}
 
 	pm->hwmon = hwmon_dev;
-#endif
+
 	return 0;
+
+error:
+	NV_ERROR(dev, "Unable to create some hwmon sysfs files: %d\n", ret);
+	hwmon_device_unregister(hwmon_dev);
+	pm->hwmon = NULL;
+	return ret;
+#else
+	pm->hwmon = NULL;
+	return 0;
+#endif
 }
 
 static void
@@ -480,6 +699,9 @@ nouveau_hwmon_fini(struct drm_device *dev)
 
 	if (pm->hwmon) {
 		sysfs_remove_group(&dev->pdev->dev.kobj, &hwmon_attrgroup);
+		sysfs_remove_group(&dev->pdev->dev.kobj, &hwmon_pwm_fan_attrgroup);
+		sysfs_remove_group(&dev->pdev->dev.kobj, &hwmon_fan_rpm_attrgroup);
+
 		hwmon_device_unregister(pm->hwmon);
 	}
 #endif

drivers/gpu/drm/nouveau/nouveau_temp.c

@@ -55,6 +55,10 @@ nouveau_temp_vbios_parse(struct drm_device *dev, u8 *temp)
 	temps->down_clock = 100;
 	temps->fan_boost = 90;
 
+	/* Set the default range for the pwm fan */
+	pm->fan.min_duty = 30;
+	pm->fan.max_duty = 100;
+
 	/* Set the known default values to setup the temperature sensor */
 	if (dev_priv->card_type >= NV_40) {
 		switch (dev_priv->chipset) {
@@ -156,11 +160,23 @@ nouveau_temp_vbios_parse(struct drm_device *dev, u8 *temp)
 		case 0x13:
 			sensor->slope_div = value;
 			break;
+		case 0x22:
+			pm->fan.min_duty = value & 0xff;
+			pm->fan.max_duty = (value & 0xff00) >> 8;
+			break;
 		}
 		temp += recordlen;
 	}
 
 	nouveau_temp_safety_checks(dev);
+
+	/* check the fan min/max settings */
+	if (pm->fan.min_duty < 10)
+		pm->fan.min_duty = 10;
+	if (pm->fan.max_duty > 100)
+		pm->fan.max_duty = 100;
+	if (pm->fan.max_duty < pm->fan.min_duty)
+		pm->fan.max_duty = pm->fan.min_duty;
 }
 
 static int