[v4,1/6] thermal: armada: add overheat interrupt support

diff --git a/drivers/thermal/armada_thermal.c b/drivers/thermal/armada_thermal.c
index 92f67d40f2e9..93ab813bfe21 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 +444,14 @@  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);
 
 unlock_mutex:
 	mutex_unlock(&priv->update_lock);
@@ -399,6 +463,123 @@  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;
+}
+
+/*
+ * 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°C
+ */
+static unsigned int hyst_levels_mc[] = {1900, 3800, 7600, 15200};
+
+static unsigned int armada_mc_to_reg_hyst(struct armada_thermal_data *data,
+					  unsigned int hyst_mc)
+{
+	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 = 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)
+			goto enable_irq;
+	} 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:
+	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;
 }