[v2,1/6] thermal: armada: add overheat interrupt support
diff mbox series

Message ID 20181123161730.11289-2-miquel.raynal@bootlin.com
State New
Headers show
Series
  • Add hw overheat IRQ support to Marvell thermal driver
Related show

Commit Message

Miquel Raynal Nov. 23, 2018, 4:17 p.m. UTC
The IP can manage to trigger interrupts on overheat situation from all
the sensors.

However, the interrupt source changes along with the last selected
source (ie. the last read sensor), which is an inconsistent behavior.
Avoid possible glitches by always selecting back only one channel which
will then be referenced as the "overheat_sensor" (arbitrarily: the first
in the DT which has a critical trip point filled in).

It is possible that the scan of all thermal zone nodes did not bring a
critical trip point from which the overheat interrupt could be
configured. In this case just complain but do not fail the probe.

Also disable sensor switch during overheat situations because changing
the channel while the system is too hot could clear the overheat state
by changing the source while the temperature is still very high.

Even if the overheat state is not declared, overheat interrupt must be
cleared by reading the DFX interrupt cause _after_ the temperature has
fallen down to the low threshold, otherwise future possible interrupts
would not be served. A work polls the corresponding register until the
overheat flag gets cleared in this case.

Suggested-by: David Sniatkiwicz <davidsn@marvell.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
 drivers/thermal/armada_thermal.c | 270 ++++++++++++++++++++++++++++++-
 1 file changed, 269 insertions(+), 1 deletion(-)

Comments

Marc Zyngier Nov. 23, 2018, 4:55 p.m. UTC | #1
On 23/11/2018 16:17, Miquel Raynal wrote:
> The IP can manage to trigger interrupts on overheat situation from all
> the sensors.
> 
> However, the interrupt source changes along with the last selected
> source (ie. the last read sensor), which is an inconsistent behavior.
> Avoid possible glitches by always selecting back only one channel which
> will then be referenced as the "overheat_sensor" (arbitrarily: the first
> in the DT which has a critical trip point filled in).
> 
> It is possible that the scan of all thermal zone nodes did not bring a
> critical trip point from which the overheat interrupt could be
> configured. In this case just complain but do not fail the probe.
> 
> Also disable sensor switch during overheat situations because changing
> the channel while the system is too hot could clear the overheat state
> by changing the source while the temperature is still very high.
> 
> Even if the overheat state is not declared, overheat interrupt must be
> cleared by reading the DFX interrupt cause _after_ the temperature has
> fallen down to the low threshold, otherwise future possible interrupts
> would not be served. A work polls the corresponding register until the
> overheat flag gets cleared in this case.
> 
> Suggested-by: David Sniatkiwicz <davidsn@marvell.com>
> Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
> ---
>  drivers/thermal/armada_thermal.c | 270 ++++++++++++++++++++++++++++++-
>  1 file changed, 269 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/thermal/armada_thermal.c b/drivers/thermal/armada_thermal.c
> index 92f67d40f2e9..55cfaee0da77 100644
> --- a/drivers/thermal/armada_thermal.c
> +++ b/drivers/thermal/armada_thermal.c
> @@ -26,6 +26,11 @@
>  #include <linux/iopoll.h>
>  #include <linux/mfd/syscon.h>
>  #include <linux/regmap.h>
> +#include <linux/interrupt.h>
> +
> +#include "thermal_core.h"
> +
> +#define TO_MCELSIUS(c)			((c) * 1000)
>  
>  /* Thermal Manager Control and Status Register */
>  #define PMU_TDC0_SW_RST_MASK		(0x1 << 1)
> @@ -61,9 +66,13 @@
>  #define CONTROL1_TSEN_AVG_MASK		0x7
>  #define CONTROL1_EXT_TSEN_SW_RESET	BIT(7)
>  #define CONTROL1_EXT_TSEN_HW_RESETn	BIT(8)
> +#define CONTROL1_TSEN_INT_EN		BIT(25)
> +#define CONTROL1_TSEN_SELECT_OFF	21
> +#define CONTROL1_TSEN_SELECT_MASK	0x3
>  
>  #define STATUS_POLL_PERIOD_US		1000
>  #define STATUS_POLL_TIMEOUT_US		100000
> +#define OVERHEAT_INT_POLL_DELAY_MS	1000
>  
>  struct armada_thermal_data;
>  
> @@ -75,7 +84,11 @@ struct armada_thermal_priv {
>  	/* serialize temperature reads/updates */
>  	struct mutex update_lock;
>  	struct armada_thermal_data *data;
> +	struct thermal_zone_device *overheat_sensor;
> +	int interrupt_source;
>  	int current_channel;
> +	long current_threshold;
> +	long current_hysteresis;
>  };
>  
>  struct armada_thermal_data {
> @@ -93,12 +106,20 @@ struct armada_thermal_data {
>  	/* Register shift and mask to access the sensor temperature */
>  	unsigned int temp_shift;
>  	unsigned int temp_mask;
> +	unsigned int thresh_shift;
> +	unsigned int hyst_shift;
> +	unsigned int hyst_mask;
>  	u32 is_valid_bit;
>  
>  	/* Syscon access */
>  	unsigned int syscon_control0_off;
>  	unsigned int syscon_control1_off;
>  	unsigned int syscon_status_off;
> +	unsigned int dfx_irq_cause_off;
> +	unsigned int dfx_irq_mask_off;
> +	unsigned int dfx_overheat_irq;
> +	unsigned int dfx_server_irq_mask_off;
> +	unsigned int dfx_server_irq_en;
>  
>  	/* One sensor is in the thermal IC, the others are in the CPUs if any */
>  	unsigned int cpu_nr;
> @@ -272,6 +293,41 @@ static bool armada_is_valid(struct armada_thermal_priv *priv)
>  	return reg & priv->data->is_valid_bit;
>  }
>  
> +static void armada_enable_overheat_interrupt(struct armada_thermal_priv *priv)
> +{
> +	struct armada_thermal_data *data = priv->data;
> +	u32 reg;
> +
> +	/* Clear DFX temperature IRQ cause */
> +	regmap_read(priv->syscon, data->dfx_irq_cause_off, &reg);
> +
> +	/* Enable DFX Temperature IRQ */
> +	regmap_read(priv->syscon, data->dfx_irq_mask_off, &reg);
> +	reg |= data->dfx_overheat_irq;
> +	regmap_write(priv->syscon, data->dfx_irq_mask_off, reg);
> +
> +	/* Enable DFX server IRQ */
> +	regmap_read(priv->syscon, data->dfx_server_irq_mask_off, &reg);
> +	reg |= data->dfx_server_irq_en;
> +	regmap_write(priv->syscon, data->dfx_server_irq_mask_off, reg);
> +
> +	/* Enable overheat interrupt */
> +	regmap_read(priv->syscon, data->syscon_control1_off, &reg);
> +	reg |= CONTROL1_TSEN_INT_EN;
> +	regmap_write(priv->syscon, data->syscon_control1_off, reg);
> +}
> +
> +static void __maybe_unused
> +armada_disable_overheat_interrupt(struct armada_thermal_priv *priv)
> +{
> +	struct armada_thermal_data *data = priv->data;
> +	u32 reg;
> +
> +	regmap_read(priv->syscon, data->syscon_control1_off, &reg);
> +	reg &= ~CONTROL1_TSEN_INT_EN;
> +	regmap_write(priv->syscon, data->syscon_control1_off, reg);
> +}
> +
>  /* There is currently no board with more than one sensor per channel */
>  static int armada_select_channel(struct armada_thermal_priv *priv, int channel)
>  {
> @@ -388,6 +444,16 @@ static int armada_get_temp(void *_sensor, int *temp)
>  
>  	/* Do the actual reading */
>  	ret = armada_read_sensor(priv, temp);
> +	if (ret)
> +		goto unlock_mutex;
> +
> +	/*
> +	 * Select back the interrupt source channel from which a potential
> +	 * critical trip point has been set.
> +	 */
> +	ret = armada_select_channel(priv, priv->interrupt_source);
> +	if (ret)
> +		goto unlock_mutex;

Do you really need a "goto" to the immediately following line?

>  
>  unlock_mutex:
>  	mutex_unlock(&priv->update_lock);
> @@ -399,6 +465,121 @@ static struct thermal_zone_of_device_ops of_ops = {
>  	.get_temp = armada_get_temp,
>  };
>  
> +static unsigned int armada_mc_to_reg_temp(struct armada_thermal_data *data,
> +					  unsigned int temp_mc)
> +{
> +	s64 b = data->coef_b;
> +	s64 m = data->coef_m;
> +	s64 div = data->coef_div;
> +	unsigned int sample;
> +
> +	if (data->inverted)
> +		sample = div_s64(((temp_mc * div) + b), m);
> +	else
> +		sample = div_s64((b - (temp_mc * div)), m);
> +
> +	return sample & data->temp_mask;
> +}
> +
> +static unsigned int armada_mc_to_reg_hyst(struct armada_thermal_data *data,
> +					  unsigned int hyst_mc)
> +{
> +	/*
> +	 * The documentation states:
> +	 * high/low watermark = threshold +/- 0.4761 * 2^(hysteresis + 2)
> +	 * which is the mathematical derivation for:
> +	 * 0x0 <=> 1.9°C, 0x1 <=> 3.8°C, 0x2 <=> 7.6°C, 0x3 <=> 15.2
> +	 */
> +	unsigned int hyst_levels_mc[] = {1900, 3800, 7600, 15200};

Why isn't this a static array rather than something you have to push on
the stack each time you execute this function?

> +	int i;
> +
> +	/*
> +	 * We will always take the smallest possible hysteresis to avoid risking
> +	 * the hardware integrity by enlarging the threshold by +8°C in the
> +	 * worst case.
> +	 */
> +	for (i = ARRAY_SIZE(hyst_levels_mc) - 1; i > 0; i--)
> +		if (hyst_mc >= hyst_levels_mc[i])
> +			break;
> +
> +	return i & data->hyst_mask;
> +}
> +
> +static void armada_set_overheat_thresholds(struct armada_thermal_priv *priv,
> +					   int thresh_mc, int hyst_mc)
> +{
> +	struct armada_thermal_data *data = priv->data;
> +	unsigned int threshold = armada_mc_to_reg_temp(data, thresh_mc);
> +	unsigned int hysteresis = armada_mc_to_reg_hyst(data, hyst_mc);
> +	u32 ctrl1;
> +
> +	regmap_read(priv->syscon, data->syscon_control1_off, &ctrl1);
> +
> +	/* Set Threshold */
> +	if (thresh_mc >= 0) {
> +		ctrl1 &= ~(data->temp_mask << data->thresh_shift);
> +		ctrl1 |= threshold << data->thresh_shift;
> +		priv->current_threshold = thresh_mc;
> +	}
> +
> +	/* Set Hysteresis */
> +	if (hyst_mc >= 0) {
> +		ctrl1 &= ~(data->hyst_mask << data->hyst_shift);
> +		ctrl1 |= hysteresis << data->hyst_shift;
> +		priv->current_hysteresis = hyst_mc;
> +	}
> +
> +	regmap_write(priv->syscon, data->syscon_control1_off, ctrl1);
> +}
> +
> +static irqreturn_t armada_overheat_isr(int irq, void *blob)
> +{
> +	/*
> +	 * Disable the IRQ and continue in thread context (thermal core
> +	 * notification and temperature monitoring).
> +	 */
> +	disable_irq_nosync(irq);
> +
> +	return IRQ_WAKE_THREAD;
> +}
> +
> +static irqreturn_t armada_overheat_isr_thread(int irq, void *blob)
> +{
> +	struct armada_thermal_priv *priv = (struct armada_thermal_priv *)blob;

Unnecessary cast.

> +	int low_threshold = priv->current_threshold - priv->current_hysteresis;
> +	int temperature;
> +	u32 dummy;
> +	int ret;
> +
> +	/* Notify the core in thread context */
> +	thermal_zone_device_update(priv->overheat_sensor,
> +				   THERMAL_EVENT_UNSPECIFIED);
> +
> +	/*
> +	 * The overheat interrupt must be cleared by reading the DFX interrupt
> +	 * cause _after_ the temperature has fallen down to the low threshold.
> +	 * Otherwise future interrupts might not be served.
> +	 */
> +	do {
> +		msleep(OVERHEAT_INT_POLL_DELAY_MS);
> +		mutex_lock(&priv->update_lock);
> +		ret = armada_read_sensor(priv, &temperature);
> +		mutex_unlock(&priv->update_lock);
> +		if (ret)
> +			return ret;

How will the interrupt fire again if you exit without re-enabling it? Is
"ret" guaranteed to be a valid irqreturn_t?

> +	} while (temperature >= low_threshold);
> +
> +	regmap_read(priv->syscon, priv->data->dfx_irq_cause_off, &dummy);
> +
> +	/* Notify the thermal core that the temperature is acceptable again */
> +	thermal_zone_device_update(priv->overheat_sensor,
> +				   THERMAL_EVENT_UNSPECIFIED);
> +
> +	enable_irq(irq);
> +
> +	return IRQ_HANDLED;
> +}
> +
>  static const struct armada_thermal_data armadaxp_data = {
>  	.init = armadaxp_init,
>  	.temp_shift = 10,
> @@ -454,6 +635,9 @@ static const struct armada_thermal_data armada_ap806_data = {
>  	.is_valid_bit = BIT(16),
>  	.temp_shift = 0,
>  	.temp_mask = 0x3ff,
> +	.thresh_shift = 3,
> +	.hyst_shift = 19,
> +	.hyst_mask = 0x3,
>  	.coef_b = -150000LL,
>  	.coef_m = 423ULL,
>  	.coef_div = 1,
> @@ -462,6 +646,11 @@ static const struct armada_thermal_data armada_ap806_data = {
>  	.syscon_control0_off = 0x84,
>  	.syscon_control1_off = 0x88,
>  	.syscon_status_off = 0x8C,
> +	.dfx_irq_cause_off = 0x108,
> +	.dfx_irq_mask_off = 0x10C,
> +	.dfx_overheat_irq = BIT(22),
> +	.dfx_server_irq_mask_off = 0x104,
> +	.dfx_server_irq_en = BIT(1),
>  	.cpu_nr = 4,
>  };
>  
> @@ -470,6 +659,9 @@ static const struct armada_thermal_data armada_cp110_data = {
>  	.is_valid_bit = BIT(10),
>  	.temp_shift = 0,
>  	.temp_mask = 0x3ff,
> +	.thresh_shift = 16,
> +	.hyst_shift = 26,
> +	.hyst_mask = 0x3,
>  	.coef_b = 1172499100ULL,
>  	.coef_m = 2000096ULL,
>  	.coef_div = 4201,
> @@ -477,6 +669,11 @@ static const struct armada_thermal_data armada_cp110_data = {
>  	.syscon_control0_off = 0x70,
>  	.syscon_control1_off = 0x74,
>  	.syscon_status_off = 0x78,
> +	.dfx_irq_cause_off = 0x108,
> +	.dfx_irq_mask_off = 0x10C,
> +	.dfx_overheat_irq = BIT(20),
> +	.dfx_server_irq_mask_off = 0x104,
> +	.dfx_server_irq_en = BIT(1),
>  };
>  
>  static const struct of_device_id armada_thermal_id_table[] = {
> @@ -592,6 +789,48 @@ static void armada_set_sane_name(struct platform_device *pdev,
>  	} while (insane_char);
>  }
>  
> +/*
> + * The IP can manage to trigger interrupts on overheat situation from all the
> + * sensors. However, the interrupt source changes along with the last selected
> + * source (ie. the last read sensor), which is an inconsistent behavior. Avoid
> + * possible glitches by always selecting back only one channel (arbitrarily: the
> + * first in the DT which has a critical trip point). We also disable sensor

The DT doesn't seem to *mandate* this. Should it? Does it also mean that
you can only have a single critical point that will generate an
interrupt on overheat?

> + * switch during overheat situations.
> + */
> +static int armada_configure_overheat_int(struct armada_thermal_priv *priv,
> +					 struct thermal_zone_device *tz,
> +					 int sensor_id)
> +{
> +	/* Retrieve the critical trip point to enable the overheat interrupt */
> +	const struct thermal_trip *trips = of_thermal_get_trip_points(tz);
> +	int ret;
> +	int i;
> +
> +	if (!trips)
> +		return -EINVAL;
> +
> +	for (i = 0; i < of_thermal_get_ntrips(tz); i++)
> +		if (trips[i].type == THERMAL_TRIP_CRITICAL)
> +			break;
> +
> +	if (i == of_thermal_get_ntrips(tz))
> +		return -EINVAL;
> +
> +	ret = armada_select_channel(priv, sensor_id);
> +	if (ret)
> +		return ret;
> +
> +	armada_set_overheat_thresholds(priv,
> +				       trips[i].temperature,
> +				       trips[i].hysteresis);
> +	priv->overheat_sensor = tz;
> +	priv->interrupt_source = sensor_id;
> +
> +	armada_enable_overheat_interrupt(priv);
> +
> +	return 0;
> +}
> +
>  static int armada_thermal_probe(struct platform_device *pdev)
>  {
>  	struct thermal_zone_device *tz;
> @@ -599,7 +838,7 @@ static int armada_thermal_probe(struct platform_device *pdev)
>  	struct armada_drvdata *drvdata;
>  	const struct of_device_id *match;
>  	struct armada_thermal_priv *priv;
> -	int sensor_id;
> +	int sensor_id, irq;
>  	int ret;
>  
>  	match = of_match_device(armada_thermal_id_table, &pdev->dev);
> @@ -669,6 +908,23 @@ static int armada_thermal_probe(struct platform_device *pdev)
>  	drvdata->data.priv = priv;
>  	platform_set_drvdata(pdev, drvdata);
>  
> +	irq = platform_get_irq(pdev, 0);
> +	if (irq == -EPROBE_DEFER)
> +		return irq;
> +
> +	/* The overheat interrupt feature is not mandatory */
> +	if (irq >= 0) {

0 is not a valid interrupt.

> +		ret = devm_request_threaded_irq(&pdev->dev, irq,
> +						armada_overheat_isr,
> +						armada_overheat_isr_thread,
> +						0, NULL, priv);
> +		if (ret) {
> +			dev_err(&pdev->dev, "Cannot request threaded IRQ %d\n",
> +				irq);
> +			return ret;
> +		}
> +	}
> +
>  	/*
>  	 * There is one channel for the IC and one per CPU (if any), each
>  	 * channel has one sensor.
> @@ -692,8 +948,20 @@ static int armada_thermal_probe(struct platform_device *pdev)
>  			devm_kfree(&pdev->dev, sensor);
>  			continue;
>  		}
> +
> +		/*
> +		 * The first channel that has a critical trip point registered
> +		 * in the DT will serve as interrupt source. Others possible
> +		 * critical trip points will simply be ignored by the driver.
> +		 */
> +		if (irq >= 0 && !priv->overheat_sensor)

Same here.

> +			armada_configure_overheat_int(priv, tz, sensor->id);
>  	}
>  
> +	/* Just complain if no overheat interrupt was set up */
> +	if (!priv->overheat_sensor)
> +		dev_warn(&pdev->dev, "Overheat interrupt not available\n");
> +
>  	return 0;
>  }
>  
> 

Thanks,

	M.
Eduardo Valentin Nov. 29, 2018, 5:12 p.m. UTC | #2
On Fri, Nov 23, 2018 at 04:55:59PM +0000, Marc Zyngier wrote:
> On 23/11/2018 16:17, Miquel Raynal wrote:
> > The IP can manage to trigger interrupts on overheat situation from all
> > the sensors.
> > 
> > However, the interrupt source changes along with the last selected
> > source (ie. the last read sensor), which is an inconsistent behavior.
> > Avoid possible glitches by always selecting back only one channel which
> > will then be referenced as the "overheat_sensor" (arbitrarily: the first
> > in the DT which has a critical trip point filled in).
> > 
> > It is possible that the scan of all thermal zone nodes did not bring a
> > critical trip point from which the overheat interrupt could be
> > configured. In this case just complain but do not fail the probe.
> > 
> > Also disable sensor switch during overheat situations because changing
> > the channel while the system is too hot could clear the overheat state
> > by changing the source while the temperature is still very high.
> > 
> > Even if the overheat state is not declared, overheat interrupt must be
> > cleared by reading the DFX interrupt cause _after_ the temperature has
> > fallen down to the low threshold, otherwise future possible interrupts
> > would not be served. A work polls the corresponding register until the
> > overheat flag gets cleared in this case.
> > 
> > Suggested-by: David Sniatkiwicz <davidsn@marvell.com>
> > Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
> > ---
> >  drivers/thermal/armada_thermal.c | 270 ++++++++++++++++++++++++++++++-
> >  1 file changed, 269 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/thermal/armada_thermal.c b/drivers/thermal/armada_thermal.c
> > index 92f67d40f2e9..55cfaee0da77 100644
> > --- a/drivers/thermal/armada_thermal.c
> > +++ b/drivers/thermal/armada_thermal.c
> > @@ -26,6 +26,11 @@
> >  #include <linux/iopoll.h>
> >  #include <linux/mfd/syscon.h>
> >  #include <linux/regmap.h>
> > +#include <linux/interrupt.h>
> > +
> > +#include "thermal_core.h"
> > +
> > +#define TO_MCELSIUS(c)			((c) * 1000)
> >  
> >  /* Thermal Manager Control and Status Register */
> >  #define PMU_TDC0_SW_RST_MASK		(0x1 << 1)
> > @@ -61,9 +66,13 @@
> >  #define CONTROL1_TSEN_AVG_MASK		0x7
> >  #define CONTROL1_EXT_TSEN_SW_RESET	BIT(7)
> >  #define CONTROL1_EXT_TSEN_HW_RESETn	BIT(8)
> > +#define CONTROL1_TSEN_INT_EN		BIT(25)
> > +#define CONTROL1_TSEN_SELECT_OFF	21
> > +#define CONTROL1_TSEN_SELECT_MASK	0x3
> >  
> >  #define STATUS_POLL_PERIOD_US		1000
> >  #define STATUS_POLL_TIMEOUT_US		100000
> > +#define OVERHEAT_INT_POLL_DELAY_MS	1000
> >  
> >  struct armada_thermal_data;
> >  
> > @@ -75,7 +84,11 @@ struct armada_thermal_priv {
> >  	/* serialize temperature reads/updates */
> >  	struct mutex update_lock;
> >  	struct armada_thermal_data *data;
> > +	struct thermal_zone_device *overheat_sensor;
> > +	int interrupt_source;
> >  	int current_channel;
> > +	long current_threshold;
> > +	long current_hysteresis;
> >  };
> >  
> >  struct armada_thermal_data {
> > @@ -93,12 +106,20 @@ struct armada_thermal_data {
> >  	/* Register shift and mask to access the sensor temperature */
> >  	unsigned int temp_shift;
> >  	unsigned int temp_mask;
> > +	unsigned int thresh_shift;
> > +	unsigned int hyst_shift;
> > +	unsigned int hyst_mask;
> >  	u32 is_valid_bit;
> >  
> >  	/* Syscon access */
> >  	unsigned int syscon_control0_off;
> >  	unsigned int syscon_control1_off;
> >  	unsigned int syscon_status_off;
> > +	unsigned int dfx_irq_cause_off;
> > +	unsigned int dfx_irq_mask_off;
> > +	unsigned int dfx_overheat_irq;
> > +	unsigned int dfx_server_irq_mask_off;
> > +	unsigned int dfx_server_irq_en;
> >  
> >  	/* One sensor is in the thermal IC, the others are in the CPUs if any */
> >  	unsigned int cpu_nr;
> > @@ -272,6 +293,41 @@ static bool armada_is_valid(struct armada_thermal_priv *priv)
> >  	return reg & priv->data->is_valid_bit;
> >  }
> >  
> > +static void armada_enable_overheat_interrupt(struct armada_thermal_priv *priv)
> > +{
> > +	struct armada_thermal_data *data = priv->data;
> > +	u32 reg;
> > +
> > +	/* Clear DFX temperature IRQ cause */
> > +	regmap_read(priv->syscon, data->dfx_irq_cause_off, &reg);
> > +
> > +	/* Enable DFX Temperature IRQ */
> > +	regmap_read(priv->syscon, data->dfx_irq_mask_off, &reg);
> > +	reg |= data->dfx_overheat_irq;
> > +	regmap_write(priv->syscon, data->dfx_irq_mask_off, reg);
> > +
> > +	/* Enable DFX server IRQ */
> > +	regmap_read(priv->syscon, data->dfx_server_irq_mask_off, &reg);
> > +	reg |= data->dfx_server_irq_en;
> > +	regmap_write(priv->syscon, data->dfx_server_irq_mask_off, reg);
> > +
> > +	/* Enable overheat interrupt */
> > +	regmap_read(priv->syscon, data->syscon_control1_off, &reg);
> > +	reg |= CONTROL1_TSEN_INT_EN;
> > +	regmap_write(priv->syscon, data->syscon_control1_off, reg);
> > +}
> > +
> > +static void __maybe_unused
> > +armada_disable_overheat_interrupt(struct armada_thermal_priv *priv)
> > +{
> > +	struct armada_thermal_data *data = priv->data;
> > +	u32 reg;
> > +
> > +	regmap_read(priv->syscon, data->syscon_control1_off, &reg);
> > +	reg &= ~CONTROL1_TSEN_INT_EN;
> > +	regmap_write(priv->syscon, data->syscon_control1_off, reg);
> > +}
> > +
> >  /* There is currently no board with more than one sensor per channel */
> >  static int armada_select_channel(struct armada_thermal_priv *priv, int channel)
> >  {
> > @@ -388,6 +444,16 @@ static int armada_get_temp(void *_sensor, int *temp)
> >  
> >  	/* Do the actual reading */
> >  	ret = armada_read_sensor(priv, temp);
> > +	if (ret)
> > +		goto unlock_mutex;
> > +
> > +	/*
> > +	 * Select back the interrupt source channel from which a potential
> > +	 * critical trip point has been set.
> > +	 */
> > +	ret = armada_select_channel(priv, priv->interrupt_source);
> > +	if (ret)
> > +		goto unlock_mutex;
> 
> Do you really need a "goto" to the immediately following line?
> 

Agreed, that goto can be removed..

> >  
> >  unlock_mutex:
> >  	mutex_unlock(&priv->update_lock);
> > @@ -399,6 +465,121 @@ static struct thermal_zone_of_device_ops of_ops = {
> >  	.get_temp = armada_get_temp,
> >  };
> >  
> > +static unsigned int armada_mc_to_reg_temp(struct armada_thermal_data *data,
> > +					  unsigned int temp_mc)
> > +{
> > +	s64 b = data->coef_b;
> > +	s64 m = data->coef_m;
> > +	s64 div = data->coef_div;
> > +	unsigned int sample;
> > +
> > +	if (data->inverted)
> > +		sample = div_s64(((temp_mc * div) + b), m);
> > +	else
> > +		sample = div_s64((b - (temp_mc * div)), m);
> > +
> > +	return sample & data->temp_mask;
> > +}
> > +
> > +static unsigned int armada_mc_to_reg_hyst(struct armada_thermal_data *data,
> > +					  unsigned int hyst_mc)
> > +{
> > +	/*
> > +	 * The documentation states:
> > +	 * high/low watermark = threshold +/- 0.4761 * 2^(hysteresis + 2)
> > +	 * which is the mathematical derivation for:
> > +	 * 0x0 <=> 1.9°C, 0x1 <=> 3.8°C, 0x2 <=> 7.6°C, 0x3 <=> 15.2
> > +	 */
> > +	unsigned int hyst_levels_mc[] = {1900, 3800, 7600, 15200};
> 
> Why isn't this a static array rather than something you have to push on
> the stack each time you execute this function?

Also, where those constants come from? Is this something the driver
needs to be updated when new chips are added for instance?

> 
> > +	int i;
> > +
> > +	/*
> > +	 * We will always take the smallest possible hysteresis to avoid risking
> > +	 * the hardware integrity by enlarging the threshold by +8°C in the
> > +	 * worst case.
> > +	 */
> > +	for (i = ARRAY_SIZE(hyst_levels_mc) - 1; i > 0; i--)
> > +		if (hyst_mc >= hyst_levels_mc[i])
> > +			break;
> > +
> > +	return i & data->hyst_mask;
> > +}
> > +
> > +static void armada_set_overheat_thresholds(struct armada_thermal_priv *priv,
> > +					   int thresh_mc, int hyst_mc)
> > +{
> > +	struct armada_thermal_data *data = priv->data;
> > +	unsigned int threshold = armada_mc_to_reg_temp(data, thresh_mc);
> > +	unsigned int hysteresis = armada_mc_to_reg_hyst(data, hyst_mc);
> > +	u32 ctrl1;
> > +
> > +	regmap_read(priv->syscon, data->syscon_control1_off, &ctrl1);
> > +
> > +	/* Set Threshold */
> > +	if (thresh_mc >= 0) {
> > +		ctrl1 &= ~(data->temp_mask << data->thresh_shift);
> > +		ctrl1 |= threshold << data->thresh_shift;
> > +		priv->current_threshold = thresh_mc;
> > +	}
> > +
> > +	/* Set Hysteresis */
> > +	if (hyst_mc >= 0) {
> > +		ctrl1 &= ~(data->hyst_mask << data->hyst_shift);
> > +		ctrl1 |= hysteresis << data->hyst_shift;
> > +		priv->current_hysteresis = hyst_mc;
> > +	}
> > +
> > +	regmap_write(priv->syscon, data->syscon_control1_off, ctrl1);
> > +}
> > +
> > +static irqreturn_t armada_overheat_isr(int irq, void *blob)
> > +{
> > +	/*
> > +	 * Disable the IRQ and continue in thread context (thermal core
> > +	 * notification and temperature monitoring).
> > +	 */
> > +	disable_irq_nosync(irq);
> > +
> > +	return IRQ_WAKE_THREAD;
> > +}
> > +
> > +static irqreturn_t armada_overheat_isr_thread(int irq, void *blob)
> > +{
> > +	struct armada_thermal_priv *priv = (struct armada_thermal_priv *)blob;
> 
> Unnecessary cast.
> 
> > +	int low_threshold = priv->current_threshold - priv->current_hysteresis;
> > +	int temperature;
> > +	u32 dummy;
> > +	int ret;
> > +
> > +	/* Notify the core in thread context */
> > +	thermal_zone_device_update(priv->overheat_sensor,
> > +				   THERMAL_EVENT_UNSPECIFIED);
> > +
> > +	/*
> > +	 * The overheat interrupt must be cleared by reading the DFX interrupt
> > +	 * cause _after_ the temperature has fallen down to the low threshold.
> > +	 * Otherwise future interrupts might not be served.
> > +	 */
> > +	do {
> > +		msleep(OVERHEAT_INT_POLL_DELAY_MS);
> > +		mutex_lock(&priv->update_lock);
> > +		ret = armada_read_sensor(priv, &temperature);
> > +		mutex_unlock(&priv->update_lock);
> > +		if (ret)
> > +			return ret;
> 
> How will the interrupt fire again if you exit without re-enabling it? Is
> "ret" guaranteed to be a valid irqreturn_t?
> 
> > +	} while (temperature >= low_threshold);
> > +
> > +	regmap_read(priv->syscon, priv->data->dfx_irq_cause_off, &dummy);
> > +
> > +	/* Notify the thermal core that the temperature is acceptable again */
> > +	thermal_zone_device_update(priv->overheat_sensor,
> > +				   THERMAL_EVENT_UNSPECIFIED);
> > +
> > +	enable_irq(irq);
> > +
> > +	return IRQ_HANDLED;
> > +}
> > +
> >  static const struct armada_thermal_data armadaxp_data = {
> >  	.init = armadaxp_init,
> >  	.temp_shift = 10,
> > @@ -454,6 +635,9 @@ static const struct armada_thermal_data armada_ap806_data = {
> >  	.is_valid_bit = BIT(16),
> >  	.temp_shift = 0,
> >  	.temp_mask = 0x3ff,
> > +	.thresh_shift = 3,
> > +	.hyst_shift = 19,
> > +	.hyst_mask = 0x3,
> >  	.coef_b = -150000LL,
> >  	.coef_m = 423ULL,
> >  	.coef_div = 1,
> > @@ -462,6 +646,11 @@ static const struct armada_thermal_data armada_ap806_data = {
> >  	.syscon_control0_off = 0x84,
> >  	.syscon_control1_off = 0x88,
> >  	.syscon_status_off = 0x8C,
> > +	.dfx_irq_cause_off = 0x108,
> > +	.dfx_irq_mask_off = 0x10C,
> > +	.dfx_overheat_irq = BIT(22),
> > +	.dfx_server_irq_mask_off = 0x104,
> > +	.dfx_server_irq_en = BIT(1),
> >  	.cpu_nr = 4,
> >  };
> >  
> > @@ -470,6 +659,9 @@ static const struct armada_thermal_data armada_cp110_data = {
> >  	.is_valid_bit = BIT(10),
> >  	.temp_shift = 0,
> >  	.temp_mask = 0x3ff,
> > +	.thresh_shift = 16,
> > +	.hyst_shift = 26,
> > +	.hyst_mask = 0x3,
> >  	.coef_b = 1172499100ULL,
> >  	.coef_m = 2000096ULL,
> >  	.coef_div = 4201,
> > @@ -477,6 +669,11 @@ static const struct armada_thermal_data armada_cp110_data = {
> >  	.syscon_control0_off = 0x70,
> >  	.syscon_control1_off = 0x74,
> >  	.syscon_status_off = 0x78,
> > +	.dfx_irq_cause_off = 0x108,
> > +	.dfx_irq_mask_off = 0x10C,
> > +	.dfx_overheat_irq = BIT(20),
> > +	.dfx_server_irq_mask_off = 0x104,
> > +	.dfx_server_irq_en = BIT(1),
> >  };
> >  
> >  static const struct of_device_id armada_thermal_id_table[] = {
> > @@ -592,6 +789,48 @@ static void armada_set_sane_name(struct platform_device *pdev,
> >  	} while (insane_char);
> >  }
> >  
> > +/*
> > + * The IP can manage to trigger interrupts on overheat situation from all the
> > + * sensors. However, the interrupt source changes along with the last selected
> > + * source (ie. the last read sensor), which is an inconsistent behavior. Avoid
> > + * possible glitches by always selecting back only one channel (arbitrarily: the
> > + * first in the DT which has a critical trip point). We also disable sensor
> 
> The DT doesn't seem to *mandate* this. Should it? Does it also mean that
> you can only have a single critical point that will generate an
> interrupt on overheat?
> 

Also, keep in mind that thermal core will shutdown the system when it
sees any zone with temp crossing the first critical trip.


> > + * switch during overheat situations.
> > + */
> > +static int armada_configure_overheat_int(struct armada_thermal_priv *priv,
> > +					 struct thermal_zone_device *tz,
> > +					 int sensor_id)
> > +{
> > +	/* Retrieve the critical trip point to enable the overheat interrupt */
> > +	const struct thermal_trip *trips = of_thermal_get_trip_points(tz);
> > +	int ret;
> > +	int i;
> > +
> > +	if (!trips)
> > +		return -EINVAL;
> > +
> > +	for (i = 0; i < of_thermal_get_ntrips(tz); i++)
> > +		if (trips[i].type == THERMAL_TRIP_CRITICAL)
> > +			break;
> > +
> > +	if (i == of_thermal_get_ntrips(tz))
> > +		return -EINVAL;
> > +
> > +	ret = armada_select_channel(priv, sensor_id);
> > +	if (ret)
> > +		return ret;
> > +
> > +	armada_set_overheat_thresholds(priv,
> > +				       trips[i].temperature,
> > +				       trips[i].hysteresis);
> > +	priv->overheat_sensor = tz;
> > +	priv->interrupt_source = sensor_id;
> > +
> > +	armada_enable_overheat_interrupt(priv);
> > +
> > +	return 0;
> > +}
> > +
> >  static int armada_thermal_probe(struct platform_device *pdev)
> >  {
> >  	struct thermal_zone_device *tz;
> > @@ -599,7 +838,7 @@ static int armada_thermal_probe(struct platform_device *pdev)
> >  	struct armada_drvdata *drvdata;
> >  	const struct of_device_id *match;
> >  	struct armada_thermal_priv *priv;
> > -	int sensor_id;
> > +	int sensor_id, irq;
> >  	int ret;
> >  
> >  	match = of_match_device(armada_thermal_id_table, &pdev->dev);
> > @@ -669,6 +908,23 @@ static int armada_thermal_probe(struct platform_device *pdev)
> >  	drvdata->data.priv = priv;
> >  	platform_set_drvdata(pdev, drvdata);
> >  
> > +	irq = platform_get_irq(pdev, 0);
> > +	if (irq == -EPROBE_DEFER)
> > +		return irq;
> > +
> > +	/* The overheat interrupt feature is not mandatory */
> > +	if (irq >= 0) {
> 
> 0 is not a valid interrupt.
> 
> > +		ret = devm_request_threaded_irq(&pdev->dev, irq,
> > +						armada_overheat_isr,
> > +						armada_overheat_isr_thread,
> > +						0, NULL, priv);
> > +		if (ret) {
> > +			dev_err(&pdev->dev, "Cannot request threaded IRQ %d\n",
> > +				irq);
> > +			return ret;
> > +		}
> > +	}
> > +
> >  	/*
> >  	 * There is one channel for the IC and one per CPU (if any), each
> >  	 * channel has one sensor.
> > @@ -692,8 +948,20 @@ static int armada_thermal_probe(struct platform_device *pdev)
> >  			devm_kfree(&pdev->dev, sensor);
> >  			continue;
> >  		}
> > +
> > +		/*
> > +		 * The first channel that has a critical trip point registered
> > +		 * in the DT will serve as interrupt source. Others possible
> > +		 * critical trip points will simply be ignored by the driver.
> > +		 */
> > +		if (irq >= 0 && !priv->overheat_sensor)
> 
> Same here.
> 
> > +			armada_configure_overheat_int(priv, tz, sensor->id);
> >  	}
> >  
> > +	/* Just complain if no overheat interrupt was set up */
> > +	if (!priv->overheat_sensor)
> > +		dev_warn(&pdev->dev, "Overheat interrupt not available\n");
> > +
> >  	return 0;
> >  }
> >  
> > 
> 
> Thanks,
> 
> 	M.
> -- 
> Jazz is not dead. It just smells funny...
Miquel Raynal Dec. 3, 2018, 3:31 p.m. UTC | #3
Hi Marc, Eduardo,

Thanks for the reviews! Two questions below.

Eduardo Valentin <edubezval@gmail.com> wrote on Thu, 29 Nov 2018
09:12:31 -0800:

> On Fri, Nov 23, 2018 at 04:55:59PM +0000, Marc Zyngier wrote:
> > On 23/11/2018 16:17, Miquel Raynal wrote:  
> > > The IP can manage to trigger interrupts on overheat situation from all
> > > the sensors.
> > > 
> > > However, the interrupt source changes along with the last selected
> > > source (ie. the last read sensor), which is an inconsistent behavior.
> > > Avoid possible glitches by always selecting back only one channel which
> > > will then be referenced as the "overheat_sensor" (arbitrarily: the first
> > > in the DT which has a critical trip point filled in).
> > > 
> > > It is possible that the scan of all thermal zone nodes did not bring a
> > > critical trip point from which the overheat interrupt could be
> > > configured. In this case just complain but do not fail the probe.
> > > 
> > > Also disable sensor switch during overheat situations because changing
> > > the channel while the system is too hot could clear the overheat state
> > > by changing the source while the temperature is still very high.
> > > 
> > > Even if the overheat state is not declared, overheat interrupt must be
> > > cleared by reading the DFX interrupt cause _after_ the temperature has
> > > fallen down to the low threshold, otherwise future possible interrupts
> > > would not be served. A work polls the corresponding register until the
> > > overheat flag gets cleared in this case.
> > > 
> > > Suggested-by: David Sniatkiwicz <davidsn@marvell.com>
> > > Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
> > > ---
> > >  drivers/thermal/armada_thermal.c | 270 ++++++++++++++++++++++++++++++-
> > >  1 file changed, 269 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/drivers/thermal/armada_thermal.c b/drivers/thermal/armada_thermal.c
> > > index 92f67d40f2e9..55cfaee0da77 100644
> > > --- a/drivers/thermal/armada_thermal.c
> > > +++ b/drivers/thermal/armada_thermal.c
> > > @@ -26,6 +26,11 @@
> > >  #include <linux/iopoll.h>
> > >  #include <linux/mfd/syscon.h>
> > >  #include <linux/regmap.h>
> > > +#include <linux/interrupt.h>
> > > +
> > > +#include "thermal_core.h"
> > > +
> > > +#define TO_MCELSIUS(c)			((c) * 1000)
> > >  
> > >  /* Thermal Manager Control and Status Register */
> > >  #define PMU_TDC0_SW_RST_MASK		(0x1 << 1)
> > > @@ -61,9 +66,13 @@
> > >  #define CONTROL1_TSEN_AVG_MASK		0x7
> > >  #define CONTROL1_EXT_TSEN_SW_RESET	BIT(7)
> > >  #define CONTROL1_EXT_TSEN_HW_RESETn	BIT(8)
> > > +#define CONTROL1_TSEN_INT_EN		BIT(25)
> > > +#define CONTROL1_TSEN_SELECT_OFF	21
> > > +#define CONTROL1_TSEN_SELECT_MASK	0x3
> > >  
> > >  #define STATUS_POLL_PERIOD_US		1000
> > >  #define STATUS_POLL_TIMEOUT_US		100000
> > > +#define OVERHEAT_INT_POLL_DELAY_MS	1000
> > >  
> > >  struct armada_thermal_data;
> > >  
> > > @@ -75,7 +84,11 @@ struct armada_thermal_priv {
> > >  	/* serialize temperature reads/updates */
> > >  	struct mutex update_lock;
> > >  	struct armada_thermal_data *data;
> > > +	struct thermal_zone_device *overheat_sensor;
> > > +	int interrupt_source;
> > >  	int current_channel;
> > > +	long current_threshold;
> > > +	long current_hysteresis;
> > >  };
> > >  
> > >  struct armada_thermal_data {
> > > @@ -93,12 +106,20 @@ struct armada_thermal_data {
> > >  	/* Register shift and mask to access the sensor temperature */
> > >  	unsigned int temp_shift;
> > >  	unsigned int temp_mask;
> > > +	unsigned int thresh_shift;
> > > +	unsigned int hyst_shift;
> > > +	unsigned int hyst_mask;
> > >  	u32 is_valid_bit;
> > >  
> > >  	/* Syscon access */
> > >  	unsigned int syscon_control0_off;
> > >  	unsigned int syscon_control1_off;
> > >  	unsigned int syscon_status_off;
> > > +	unsigned int dfx_irq_cause_off;
> > > +	unsigned int dfx_irq_mask_off;
> > > +	unsigned int dfx_overheat_irq;
> > > +	unsigned int dfx_server_irq_mask_off;
> > > +	unsigned int dfx_server_irq_en;
> > >  
> > >  	/* One sensor is in the thermal IC, the others are in the CPUs if any */
> > >  	unsigned int cpu_nr;
> > > @@ -272,6 +293,41 @@ static bool armada_is_valid(struct armada_thermal_priv *priv)
> > >  	return reg & priv->data->is_valid_bit;
> > >  }
> > >  
> > > +static void armada_enable_overheat_interrupt(struct armada_thermal_priv *priv)
> > > +{
> > > +	struct armada_thermal_data *data = priv->data;
> > > +	u32 reg;
> > > +
> > > +	/* Clear DFX temperature IRQ cause */
> > > +	regmap_read(priv->syscon, data->dfx_irq_cause_off, &reg);
> > > +
> > > +	/* Enable DFX Temperature IRQ */
> > > +	regmap_read(priv->syscon, data->dfx_irq_mask_off, &reg);
> > > +	reg |= data->dfx_overheat_irq;
> > > +	regmap_write(priv->syscon, data->dfx_irq_mask_off, reg);
> > > +
> > > +	/* Enable DFX server IRQ */
> > > +	regmap_read(priv->syscon, data->dfx_server_irq_mask_off, &reg);
> > > +	reg |= data->dfx_server_irq_en;
> > > +	regmap_write(priv->syscon, data->dfx_server_irq_mask_off, reg);
> > > +
> > > +	/* Enable overheat interrupt */
> > > +	regmap_read(priv->syscon, data->syscon_control1_off, &reg);
> > > +	reg |= CONTROL1_TSEN_INT_EN;
> > > +	regmap_write(priv->syscon, data->syscon_control1_off, reg);
> > > +}
> > > +
> > > +static void __maybe_unused
> > > +armada_disable_overheat_interrupt(struct armada_thermal_priv *priv)
> > > +{
> > > +	struct armada_thermal_data *data = priv->data;
> > > +	u32 reg;
> > > +
> > > +	regmap_read(priv->syscon, data->syscon_control1_off, &reg);
> > > +	reg &= ~CONTROL1_TSEN_INT_EN;
> > > +	regmap_write(priv->syscon, data->syscon_control1_off, reg);
> > > +}
> > > +
> > >  /* There is currently no board with more than one sensor per channel */
> > >  static int armada_select_channel(struct armada_thermal_priv *priv, int channel)
> > >  {
> > > @@ -388,6 +444,16 @@ static int armada_get_temp(void *_sensor, int *temp)
> > >  
> > >  	/* Do the actual reading */
> > >  	ret = armada_read_sensor(priv, temp);
> > > +	if (ret)
> > > +		goto unlock_mutex;
> > > +
> > > +	/*
> > > +	 * Select back the interrupt source channel from which a potential
> > > +	 * critical trip point has been set.
> > > +	 */
> > > +	ret = armada_select_channel(priv, priv->interrupt_source);
> > > +	if (ret)
> > > +		goto unlock_mutex;  
> > 
> > Do you really need a "goto" to the immediately following line?
> >   
> 
> Agreed, that goto can be removed..

Sure.

> 
> > >  
> > >  unlock_mutex:
> > >  	mutex_unlock(&priv->update_lock);
> > > @@ -399,6 +465,121 @@ static struct thermal_zone_of_device_ops of_ops = {
> > >  	.get_temp = armada_get_temp,
> > >  };
> > >  
> > > +static unsigned int armada_mc_to_reg_temp(struct armada_thermal_data *data,
> > > +					  unsigned int temp_mc)
> > > +{
> > > +	s64 b = data->coef_b;
> > > +	s64 m = data->coef_m;
> > > +	s64 div = data->coef_div;
> > > +	unsigned int sample;
> > > +
> > > +	if (data->inverted)
> > > +		sample = div_s64(((temp_mc * div) + b), m);
> > > +	else
> > > +		sample = div_s64((b - (temp_mc * div)), m);
> > > +
> > > +	return sample & data->temp_mask;
> > > +}
> > > +
> > > +static unsigned int armada_mc_to_reg_hyst(struct armada_thermal_data *data,
> > > +					  unsigned int hyst_mc)
> > > +{
> > > +	/*
> > > +	 * The documentation states:
> > > +	 * high/low watermark = threshold +/- 0.4761 * 2^(hysteresis + 2)
> > > +	 * which is the mathematical derivation for:
> > > +	 * 0x0 <=> 1.9°C, 0x1 <=> 3.8°C, 0x2 <=> 7.6°C, 0x3 <=> 15.2
> > > +	 */
> > > +	unsigned int hyst_levels_mc[] = {1900, 3800, 7600, 15200};  
> > 
> > Why isn't this a static array rather than something you have to push on
> > the stack each time you execute this function?  

Yes, this should definitely be declared in a static array.

> 
> Also, where those constants come from? Is this something the driver
> needs to be updated when new chips are added for instance?

Well, I can't tell for sure. These values are derived thanks to the
mathematical function in the comment. I don't think this is subject to
change in the future but you never know. I propose to just have one
static array for now, if we need to tweak these parameters for similar
IPs in the future we will integrate it in platform data. What do you
think?

> 
> >   
> > > +	int i;
> > > +
> > > +	/*
> > > +	 * We will always take the smallest possible hysteresis to avoid risking
> > > +	 * the hardware integrity by enlarging the threshold by +8°C in the
> > > +	 * worst case.
> > > +	 */
> > > +	for (i = ARRAY_SIZE(hyst_levels_mc) - 1; i > 0; i--)
> > > +		if (hyst_mc >= hyst_levels_mc[i])
> > > +			break;
> > > +
> > > +	return i & data->hyst_mask;
> > > +}
> > > +
> > > +static void armada_set_overheat_thresholds(struct armada_thermal_priv *priv,
> > > +					   int thresh_mc, int hyst_mc)
> > > +{
> > > +	struct armada_thermal_data *data = priv->data;
> > > +	unsigned int threshold = armada_mc_to_reg_temp(data, thresh_mc);
> > > +	unsigned int hysteresis = armada_mc_to_reg_hyst(data, hyst_mc);
> > > +	u32 ctrl1;
> > > +
> > > +	regmap_read(priv->syscon, data->syscon_control1_off, &ctrl1);
> > > +
> > > +	/* Set Threshold */
> > > +	if (thresh_mc >= 0) {
> > > +		ctrl1 &= ~(data->temp_mask << data->thresh_shift);
> > > +		ctrl1 |= threshold << data->thresh_shift;
> > > +		priv->current_threshold = thresh_mc;
> > > +	}
> > > +
> > > +	/* Set Hysteresis */
> > > +	if (hyst_mc >= 0) {
> > > +		ctrl1 &= ~(data->hyst_mask << data->hyst_shift);
> > > +		ctrl1 |= hysteresis << data->hyst_shift;
> > > +		priv->current_hysteresis = hyst_mc;
> > > +	}
> > > +
> > > +	regmap_write(priv->syscon, data->syscon_control1_off, ctrl1);
> > > +}
> > > +
> > > +static irqreturn_t armada_overheat_isr(int irq, void *blob)
> > > +{
> > > +	/*
> > > +	 * Disable the IRQ and continue in thread context (thermal core
> > > +	 * notification and temperature monitoring).
> > > +	 */
> > > +	disable_irq_nosync(irq);
> > > +
> > > +	return IRQ_WAKE_THREAD;
> > > +}
> > > +
> > > +static irqreturn_t armada_overheat_isr_thread(int irq, void *blob)
> > > +{
> > > +	struct armada_thermal_priv *priv = (struct armada_thermal_priv *)blob;  
> > 
> > Unnecessary cast.

Ok.

> >   
> > > +	int low_threshold = priv->current_threshold - priv->current_hysteresis;
> > > +	int temperature;
> > > +	u32 dummy;
> > > +	int ret;
> > > +
> > > +	/* Notify the core in thread context */
> > > +	thermal_zone_device_update(priv->overheat_sensor,
> > > +				   THERMAL_EVENT_UNSPECIFIED);
> > > +
> > > +	/*
> > > +	 * The overheat interrupt must be cleared by reading the DFX interrupt
> > > +	 * cause _after_ the temperature has fallen down to the low threshold.
> > > +	 * Otherwise future interrupts might not be served.
> > > +	 */
> > > +	do {
> > > +		msleep(OVERHEAT_INT_POLL_DELAY_MS);
> > > +		mutex_lock(&priv->update_lock);
> > > +		ret = armada_read_sensor(priv, &temperature);
> > > +		mutex_unlock(&priv->update_lock);
> > > +		if (ret)
> > > +			return ret;  
> > 
> > How will the interrupt fire again if you exit without re-enabling it? Is
> > "ret" guaranteed to be a valid irqreturn_t?

You are right this structure is wrong, I will find a better way to
handle errors.

> >   
> > > +	} while (temperature >= low_threshold);
> > > +
> > > +	regmap_read(priv->syscon, priv->data->dfx_irq_cause_off, &dummy);
> > > +
> > > +	/* Notify the thermal core that the temperature is acceptable again */
> > > +	thermal_zone_device_update(priv->overheat_sensor,
> > > +				   THERMAL_EVENT_UNSPECIFIED);
> > > +
> > > +	enable_irq(irq);
> > > +
> > > +	return IRQ_HANDLED;
> > > +}
> > > +
> > >  static const struct armada_thermal_data armadaxp_data = {
> > >  	.init = armadaxp_init,
> > >  	.temp_shift = 10,
> > > @@ -454,6 +635,9 @@ static const struct armada_thermal_data armada_ap806_data = {
> > >  	.is_valid_bit = BIT(16),
> > >  	.temp_shift = 0,
> > >  	.temp_mask = 0x3ff,
> > > +	.thresh_shift = 3,
> > > +	.hyst_shift = 19,
> > > +	.hyst_mask = 0x3,
> > >  	.coef_b = -150000LL,
> > >  	.coef_m = 423ULL,
> > >  	.coef_div = 1,
> > > @@ -462,6 +646,11 @@ static const struct armada_thermal_data armada_ap806_data = {
> > >  	.syscon_control0_off = 0x84,
> > >  	.syscon_control1_off = 0x88,
> > >  	.syscon_status_off = 0x8C,
> > > +	.dfx_irq_cause_off = 0x108,
> > > +	.dfx_irq_mask_off = 0x10C,
> > > +	.dfx_overheat_irq = BIT(22),
> > > +	.dfx_server_irq_mask_off = 0x104,
> > > +	.dfx_server_irq_en = BIT(1),
> > >  	.cpu_nr = 4,
> > >  };
> > >  
> > > @@ -470,6 +659,9 @@ static const struct armada_thermal_data armada_cp110_data = {
> > >  	.is_valid_bit = BIT(10),
> > >  	.temp_shift = 0,
> > >  	.temp_mask = 0x3ff,
> > > +	.thresh_shift = 16,
> > > +	.hyst_shift = 26,
> > > +	.hyst_mask = 0x3,
> > >  	.coef_b = 1172499100ULL,
> > >  	.coef_m = 2000096ULL,
> > >  	.coef_div = 4201,
> > > @@ -477,6 +669,11 @@ static const struct armada_thermal_data armada_cp110_data = {
> > >  	.syscon_control0_off = 0x70,
> > >  	.syscon_control1_off = 0x74,
> > >  	.syscon_status_off = 0x78,
> > > +	.dfx_irq_cause_off = 0x108,
> > > +	.dfx_irq_mask_off = 0x10C,
> > > +	.dfx_overheat_irq = BIT(20),
> > > +	.dfx_server_irq_mask_off = 0x104,
> > > +	.dfx_server_irq_en = BIT(1),
> > >  };
> > >  
> > >  static const struct of_device_id armada_thermal_id_table[] = {
> > > @@ -592,6 +789,48 @@ static void armada_set_sane_name(struct platform_device *pdev,
> > >  	} while (insane_char);
> > >  }
> > >  
> > > +/*
> > > + * The IP can manage to trigger interrupts on overheat situation from all the
> > > + * sensors. However, the interrupt source changes along with the last selected
> > > + * source (ie. the last read sensor), which is an inconsistent behavior. Avoid
> > > + * possible glitches by always selecting back only one channel (arbitrarily: the
> > > + * first in the DT which has a critical trip point). We also disable sensor  
> > 
> > The DT doesn't seem to *mandate* this. Should it? Does it also mean that
> > you can only have a single critical point that will generate an
> > interrupt on overheat?

Yes:
* the IP only supports one single critical point that will generate
  an interrupt,
* any channel can trigger the interrupt,
* one (and only one) channel is selected at any time, it is the one
  that will trigger the interrupt.

> 
> Also, keep in mind that thermal core will shutdown the system when it
> sees any zone with temp crossing the first critical trip.

I had in mind the possibility to declare a trip point less important
than "critical" from which actions could take place in order to reduce
the temperature and try to avoid the shutdown. If you think this is not
useful I might probably simplify a lot the interrupt handling. But
then, there is no way to recover from such interrupt.

> 
> 
> > > + * switch during overheat situations.
> > > + */
> > > +static int armada_configure_overheat_int(struct armada_thermal_priv *priv,
> > > +					 struct thermal_zone_device *tz,
> > > +					 int sensor_id)
> > > +{
> > > +	/* Retrieve the critical trip point to enable the overheat interrupt */
> > > +	const struct thermal_trip *trips = of_thermal_get_trip_points(tz);
> > > +	int ret;
> > > +	int i;
> > > +
> > > +	if (!trips)
> > > +		return -EINVAL;
> > > +
> > > +	for (i = 0; i < of_thermal_get_ntrips(tz); i++)
> > > +		if (trips[i].type == THERMAL_TRIP_CRITICAL)
> > > +			break;
> > > +
> > > +	if (i == of_thermal_get_ntrips(tz))
> > > +		return -EINVAL;
> > > +
> > > +	ret = armada_select_channel(priv, sensor_id);
> > > +	if (ret)
> > > +		return ret;
> > > +
> > > +	armada_set_overheat_thresholds(priv,
> > > +				       trips[i].temperature,
> > > +				       trips[i].hysteresis);
> > > +	priv->overheat_sensor = tz;
> > > +	priv->interrupt_source = sensor_id;
> > > +
> > > +	armada_enable_overheat_interrupt(priv);
> > > +
> > > +	return 0;
> > > +}
> > > +
> > >  static int armada_thermal_probe(struct platform_device *pdev)
> > >  {
> > >  	struct thermal_zone_device *tz;
> > > @@ -599,7 +838,7 @@ static int armada_thermal_probe(struct platform_device *pdev)
> > >  	struct armada_drvdata *drvdata;
> > >  	const struct of_device_id *match;
> > >  	struct armada_thermal_priv *priv;
> > > -	int sensor_id;
> > > +	int sensor_id, irq;
> > >  	int ret;
> > >  
> > >  	match = of_match_device(armada_thermal_id_table, &pdev->dev);
> > > @@ -669,6 +908,23 @@ static int armada_thermal_probe(struct platform_device *pdev)
> > >  	drvdata->data.priv = priv;
> > >  	platform_set_drvdata(pdev, drvdata);
> > >  
> > > +	irq = platform_get_irq(pdev, 0);
> > > +	if (irq == -EPROBE_DEFER)
> > > +		return irq;
> > > +
> > > +	/* The overheat interrupt feature is not mandatory */
> > > +	if (irq >= 0) {  
> > 
> > 0 is not a valid interrupt.

Right.

> >   
> > > +		ret = devm_request_threaded_irq(&pdev->dev, irq,
> > > +						armada_overheat_isr,
> > > +						armada_overheat_isr_thread,
> > > +						0, NULL, priv);
> > > +		if (ret) {
> > > +			dev_err(&pdev->dev, "Cannot request threaded IRQ %d\n",
> > > +				irq);
> > > +			return ret;
> > > +		}
> > > +	}
> > > +
> > >  	/*
> > >  	 * There is one channel for the IC and one per CPU (if any), each
> > >  	 * channel has one sensor.
> > > @@ -692,8 +948,20 @@ static int armada_thermal_probe(struct platform_device *pdev)
> > >  			devm_kfree(&pdev->dev, sensor);
> > >  			continue;
> > >  		}
> > > +
> > > +		/*
> > > +		 * The first channel that has a critical trip point registered
> > > +		 * in the DT will serve as interrupt source. Others possible
> > > +		 * critical trip points will simply be ignored by the driver.
> > > +		 */
> > > +		if (irq >= 0 && !priv->overheat_sensor)  
> > 
> > Same here.

Yes.

> >   
> > > +			armada_configure_overheat_int(priv, tz, sensor->id);
> > >  	}
> > >  
> > > +	/* Just complain if no overheat interrupt was set up */
> > > +	if (!priv->overheat_sensor)
> > > +		dev_warn(&pdev->dev, "Overheat interrupt not available\n");
> > > +
> > >  	return 0;
> > >  }
> > >  
> > >   
> > 
> > Thanks,
> > 
> > 	M.
> > -- 
> > Jazz is not dead. It just smells funny...  


Thanks,
Miquèl

Patch
diff mbox series

diff --git a/drivers/thermal/armada_thermal.c b/drivers/thermal/armada_thermal.c
index 92f67d40f2e9..55cfaee0da77 100644
--- a/drivers/thermal/armada_thermal.c
+++ b/drivers/thermal/armada_thermal.c
@@ -26,6 +26,11 @@ 
 #include <linux/iopoll.h>
 #include <linux/mfd/syscon.h>
 #include <linux/regmap.h>
+#include <linux/interrupt.h>
+
+#include "thermal_core.h"
+
+#define TO_MCELSIUS(c)			((c) * 1000)
 
 /* Thermal Manager Control and Status Register */
 #define PMU_TDC0_SW_RST_MASK		(0x1 << 1)
@@ -61,9 +66,13 @@ 
 #define CONTROL1_TSEN_AVG_MASK		0x7
 #define CONTROL1_EXT_TSEN_SW_RESET	BIT(7)
 #define CONTROL1_EXT_TSEN_HW_RESETn	BIT(8)
+#define CONTROL1_TSEN_INT_EN		BIT(25)
+#define CONTROL1_TSEN_SELECT_OFF	21
+#define CONTROL1_TSEN_SELECT_MASK	0x3
 
 #define STATUS_POLL_PERIOD_US		1000
 #define STATUS_POLL_TIMEOUT_US		100000
+#define OVERHEAT_INT_POLL_DELAY_MS	1000
 
 struct armada_thermal_data;
 
@@ -75,7 +84,11 @@  struct armada_thermal_priv {
 	/* serialize temperature reads/updates */
 	struct mutex update_lock;
 	struct armada_thermal_data *data;
+	struct thermal_zone_device *overheat_sensor;
+	int interrupt_source;
 	int current_channel;
+	long current_threshold;
+	long current_hysteresis;
 };
 
 struct armada_thermal_data {
@@ -93,12 +106,20 @@  struct armada_thermal_data {
 	/* Register shift and mask to access the sensor temperature */
 	unsigned int temp_shift;
 	unsigned int temp_mask;
+	unsigned int thresh_shift;
+	unsigned int hyst_shift;
+	unsigned int hyst_mask;
 	u32 is_valid_bit;
 
 	/* Syscon access */
 	unsigned int syscon_control0_off;
 	unsigned int syscon_control1_off;
 	unsigned int syscon_status_off;
+	unsigned int dfx_irq_cause_off;
+	unsigned int dfx_irq_mask_off;
+	unsigned int dfx_overheat_irq;
+	unsigned int dfx_server_irq_mask_off;
+	unsigned int dfx_server_irq_en;
 
 	/* One sensor is in the thermal IC, the others are in the CPUs if any */
 	unsigned int cpu_nr;
@@ -272,6 +293,41 @@  static bool armada_is_valid(struct armada_thermal_priv *priv)
 	return reg & priv->data->is_valid_bit;
 }
 
+static void armada_enable_overheat_interrupt(struct armada_thermal_priv *priv)
+{
+	struct armada_thermal_data *data = priv->data;
+	u32 reg;
+
+	/* Clear DFX temperature IRQ cause */
+	regmap_read(priv->syscon, data->dfx_irq_cause_off, &reg);
+
+	/* Enable DFX Temperature IRQ */
+	regmap_read(priv->syscon, data->dfx_irq_mask_off, &reg);
+	reg |= data->dfx_overheat_irq;
+	regmap_write(priv->syscon, data->dfx_irq_mask_off, reg);
+
+	/* Enable DFX server IRQ */
+	regmap_read(priv->syscon, data->dfx_server_irq_mask_off, &reg);
+	reg |= data->dfx_server_irq_en;
+	regmap_write(priv->syscon, data->dfx_server_irq_mask_off, reg);
+
+	/* Enable overheat interrupt */
+	regmap_read(priv->syscon, data->syscon_control1_off, &reg);
+	reg |= CONTROL1_TSEN_INT_EN;
+	regmap_write(priv->syscon, data->syscon_control1_off, reg);
+}
+
+static void __maybe_unused
+armada_disable_overheat_interrupt(struct armada_thermal_priv *priv)
+{
+	struct armada_thermal_data *data = priv->data;
+	u32 reg;
+
+	regmap_read(priv->syscon, data->syscon_control1_off, &reg);
+	reg &= ~CONTROL1_TSEN_INT_EN;
+	regmap_write(priv->syscon, data->syscon_control1_off, reg);
+}
+
 /* There is currently no board with more than one sensor per channel */
 static int armada_select_channel(struct armada_thermal_priv *priv, int channel)
 {
@@ -388,6 +444,16 @@  static int armada_get_temp(void *_sensor, int *temp)
 
 	/* Do the actual reading */
 	ret = armada_read_sensor(priv, temp);
+	if (ret)
+		goto unlock_mutex;
+
+	/*
+	 * Select back the interrupt source channel from which a potential
+	 * critical trip point has been set.
+	 */
+	ret = armada_select_channel(priv, priv->interrupt_source);
+	if (ret)
+		goto unlock_mutex;
 
 unlock_mutex:
 	mutex_unlock(&priv->update_lock);
@@ -399,6 +465,121 @@  static struct thermal_zone_of_device_ops of_ops = {
 	.get_temp = armada_get_temp,
 };
 
+static unsigned int armada_mc_to_reg_temp(struct armada_thermal_data *data,
+					  unsigned int temp_mc)
+{
+	s64 b = data->coef_b;
+	s64 m = data->coef_m;
+	s64 div = data->coef_div;
+	unsigned int sample;
+
+	if (data->inverted)
+		sample = div_s64(((temp_mc * div) + b), m);
+	else
+		sample = div_s64((b - (temp_mc * div)), m);
+
+	return sample & data->temp_mask;
+}
+
+static unsigned int armada_mc_to_reg_hyst(struct armada_thermal_data *data,
+					  unsigned int hyst_mc)
+{
+	/*
+	 * The documentation states:
+	 * high/low watermark = threshold +/- 0.4761 * 2^(hysteresis + 2)
+	 * which is the mathematical derivation for:
+	 * 0x0 <=> 1.9°C, 0x1 <=> 3.8°C, 0x2 <=> 7.6°C, 0x3 <=> 15.2
+	 */
+	unsigned int hyst_levels_mc[] = {1900, 3800, 7600, 15200};
+	int i;
+
+	/*
+	 * We will always take the smallest possible hysteresis to avoid risking
+	 * the hardware integrity by enlarging the threshold by +8°C in the
+	 * worst case.
+	 */
+	for (i = ARRAY_SIZE(hyst_levels_mc) - 1; i > 0; i--)
+		if (hyst_mc >= hyst_levels_mc[i])
+			break;
+
+	return i & data->hyst_mask;
+}
+
+static void armada_set_overheat_thresholds(struct armada_thermal_priv *priv,
+					   int thresh_mc, int hyst_mc)
+{
+	struct armada_thermal_data *data = priv->data;
+	unsigned int threshold = armada_mc_to_reg_temp(data, thresh_mc);
+	unsigned int hysteresis = armada_mc_to_reg_hyst(data, hyst_mc);
+	u32 ctrl1;
+
+	regmap_read(priv->syscon, data->syscon_control1_off, &ctrl1);
+
+	/* Set Threshold */
+	if (thresh_mc >= 0) {
+		ctrl1 &= ~(data->temp_mask << data->thresh_shift);
+		ctrl1 |= threshold << data->thresh_shift;
+		priv->current_threshold = thresh_mc;
+	}
+
+	/* Set Hysteresis */
+	if (hyst_mc >= 0) {
+		ctrl1 &= ~(data->hyst_mask << data->hyst_shift);
+		ctrl1 |= hysteresis << data->hyst_shift;
+		priv->current_hysteresis = hyst_mc;
+	}
+
+	regmap_write(priv->syscon, data->syscon_control1_off, ctrl1);
+}
+
+static irqreturn_t armada_overheat_isr(int irq, void *blob)
+{
+	/*
+	 * Disable the IRQ and continue in thread context (thermal core
+	 * notification and temperature monitoring).
+	 */
+	disable_irq_nosync(irq);
+
+	return IRQ_WAKE_THREAD;
+}
+
+static irqreturn_t armada_overheat_isr_thread(int irq, void *blob)
+{
+	struct armada_thermal_priv *priv = (struct armada_thermal_priv *)blob;
+	int low_threshold = priv->current_threshold - priv->current_hysteresis;
+	int temperature;
+	u32 dummy;
+	int ret;
+
+	/* Notify the core in thread context */
+	thermal_zone_device_update(priv->overheat_sensor,
+				   THERMAL_EVENT_UNSPECIFIED);
+
+	/*
+	 * The overheat interrupt must be cleared by reading the DFX interrupt
+	 * cause _after_ the temperature has fallen down to the low threshold.
+	 * Otherwise future interrupts might not be served.
+	 */
+	do {
+		msleep(OVERHEAT_INT_POLL_DELAY_MS);
+		mutex_lock(&priv->update_lock);
+		ret = armada_read_sensor(priv, &temperature);
+		mutex_unlock(&priv->update_lock);
+		if (ret)
+			return ret;
+	} while (temperature >= low_threshold);
+
+	regmap_read(priv->syscon, priv->data->dfx_irq_cause_off, &dummy);
+
+	/* Notify the thermal core that the temperature is acceptable again */
+	thermal_zone_device_update(priv->overheat_sensor,
+				   THERMAL_EVENT_UNSPECIFIED);
+
+	enable_irq(irq);
+
+	return IRQ_HANDLED;
+}
+
 static const struct armada_thermal_data armadaxp_data = {
 	.init = armadaxp_init,
 	.temp_shift = 10,
@@ -454,6 +635,9 @@  static const struct armada_thermal_data armada_ap806_data = {
 	.is_valid_bit = BIT(16),
 	.temp_shift = 0,
 	.temp_mask = 0x3ff,
+	.thresh_shift = 3,
+	.hyst_shift = 19,
+	.hyst_mask = 0x3,
 	.coef_b = -150000LL,
 	.coef_m = 423ULL,
 	.coef_div = 1,
@@ -462,6 +646,11 @@  static const struct armada_thermal_data armada_ap806_data = {
 	.syscon_control0_off = 0x84,
 	.syscon_control1_off = 0x88,
 	.syscon_status_off = 0x8C,
+	.dfx_irq_cause_off = 0x108,
+	.dfx_irq_mask_off = 0x10C,
+	.dfx_overheat_irq = BIT(22),
+	.dfx_server_irq_mask_off = 0x104,
+	.dfx_server_irq_en = BIT(1),
 	.cpu_nr = 4,
 };
 
@@ -470,6 +659,9 @@  static const struct armada_thermal_data armada_cp110_data = {
 	.is_valid_bit = BIT(10),
 	.temp_shift = 0,
 	.temp_mask = 0x3ff,
+	.thresh_shift = 16,
+	.hyst_shift = 26,
+	.hyst_mask = 0x3,
 	.coef_b = 1172499100ULL,
 	.coef_m = 2000096ULL,
 	.coef_div = 4201,
@@ -477,6 +669,11 @@  static const struct armada_thermal_data armada_cp110_data = {
 	.syscon_control0_off = 0x70,
 	.syscon_control1_off = 0x74,
 	.syscon_status_off = 0x78,
+	.dfx_irq_cause_off = 0x108,
+	.dfx_irq_mask_off = 0x10C,
+	.dfx_overheat_irq = BIT(20),
+	.dfx_server_irq_mask_off = 0x104,
+	.dfx_server_irq_en = BIT(1),
 };
 
 static const struct of_device_id armada_thermal_id_table[] = {
@@ -592,6 +789,48 @@  static void armada_set_sane_name(struct platform_device *pdev,
 	} while (insane_char);
 }
 
+/*
+ * The IP can manage to trigger interrupts on overheat situation from all the
+ * sensors. However, the interrupt source changes along with the last selected
+ * source (ie. the last read sensor), which is an inconsistent behavior. Avoid
+ * possible glitches by always selecting back only one channel (arbitrarily: the
+ * first in the DT which has a critical trip point). We also disable sensor
+ * switch during overheat situations.
+ */
+static int armada_configure_overheat_int(struct armada_thermal_priv *priv,
+					 struct thermal_zone_device *tz,
+					 int sensor_id)
+{
+	/* Retrieve the critical trip point to enable the overheat interrupt */
+	const struct thermal_trip *trips = of_thermal_get_trip_points(tz);
+	int ret;
+	int i;
+
+	if (!trips)
+		return -EINVAL;
+
+	for (i = 0; i < of_thermal_get_ntrips(tz); i++)
+		if (trips[i].type == THERMAL_TRIP_CRITICAL)
+			break;
+
+	if (i == of_thermal_get_ntrips(tz))
+		return -EINVAL;
+
+	ret = armada_select_channel(priv, sensor_id);
+	if (ret)
+		return ret;
+
+	armada_set_overheat_thresholds(priv,
+				       trips[i].temperature,
+				       trips[i].hysteresis);
+	priv->overheat_sensor = tz;
+	priv->interrupt_source = sensor_id;
+
+	armada_enable_overheat_interrupt(priv);
+
+	return 0;
+}
+
 static int armada_thermal_probe(struct platform_device *pdev)
 {
 	struct thermal_zone_device *tz;
@@ -599,7 +838,7 @@  static int armada_thermal_probe(struct platform_device *pdev)
 	struct armada_drvdata *drvdata;
 	const struct of_device_id *match;
 	struct armada_thermal_priv *priv;
-	int sensor_id;
+	int sensor_id, irq;
 	int ret;
 
 	match = of_match_device(armada_thermal_id_table, &pdev->dev);
@@ -669,6 +908,23 @@  static int armada_thermal_probe(struct platform_device *pdev)
 	drvdata->data.priv = priv;
 	platform_set_drvdata(pdev, drvdata);
 
+	irq = platform_get_irq(pdev, 0);
+	if (irq == -EPROBE_DEFER)
+		return irq;
+
+	/* The overheat interrupt feature is not mandatory */
+	if (irq >= 0) {
+		ret = devm_request_threaded_irq(&pdev->dev, irq,
+						armada_overheat_isr,
+						armada_overheat_isr_thread,
+						0, NULL, priv);
+		if (ret) {
+			dev_err(&pdev->dev, "Cannot request threaded IRQ %d\n",
+				irq);
+			return ret;
+		}
+	}
+
 	/*
 	 * There is one channel for the IC and one per CPU (if any), each
 	 * channel has one sensor.
@@ -692,8 +948,20 @@  static int armada_thermal_probe(struct platform_device *pdev)
 			devm_kfree(&pdev->dev, sensor);
 			continue;
 		}
+
+		/*
+		 * The first channel that has a critical trip point registered
+		 * in the DT will serve as interrupt source. Others possible
+		 * critical trip points will simply be ignored by the driver.
+		 */
+		if (irq >= 0 && !priv->overheat_sensor)
+			armada_configure_overheat_int(priv, tz, sensor->id);
 	}
 
+	/* Just complain if no overheat interrupt was set up */
+	if (!priv->overheat_sensor)
+		dev_warn(&pdev->dev, "Overheat interrupt not available\n");
+
 	return 0;
 }