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thermal: imx: implement thermal alarm interrupt handling
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Enable automatic measurements at 10 Hz and use the alarm interrupt to react
more quickly to sudden temperature changes above the passive or critical
temperature trip points.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Acked-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
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Philipp Zabel authored and Zhang Rui committed Aug 15, 2013
1 parent 017e514 commit 37713a1
Showing 1 changed file with 127 additions and 13 deletions.
140 changes: 127 additions & 13 deletions drivers/thermal/imx_thermal.c
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Original file line number Diff line number Diff line change
Expand Up @@ -12,6 +12,7 @@
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/mfd/syscon.h>
Expand All @@ -31,6 +32,8 @@
#define MISC0_REFTOP_SELBIASOFF (1 << 3)

#define TEMPSENSE0 0x0180
#define TEMPSENSE0_ALARM_VALUE_SHIFT 20
#define TEMPSENSE0_ALARM_VALUE_MASK (0xfff << TEMPSENSE0_ALARM_VALUE_SHIFT)
#define TEMPSENSE0_TEMP_CNT_SHIFT 8
#define TEMPSENSE0_TEMP_CNT_MASK (0xfff << TEMPSENSE0_TEMP_CNT_SHIFT)
#define TEMPSENSE0_FINISHED (1 << 2)
Expand Down Expand Up @@ -66,33 +69,62 @@ struct imx_thermal_data {
int c1, c2; /* See formula in imx_get_sensor_data() */
unsigned long temp_passive;
unsigned long temp_critical;
unsigned long alarm_temp;
unsigned long last_temp;
bool irq_enabled;
int irq;
};

static void imx_set_alarm_temp(struct imx_thermal_data *data,
signed long alarm_temp)
{
struct regmap *map = data->tempmon;
int alarm_value;

data->alarm_temp = alarm_temp;
alarm_value = (alarm_temp - data->c2) / data->c1;
regmap_write(map, TEMPSENSE0 + REG_CLR, TEMPSENSE0_ALARM_VALUE_MASK);
regmap_write(map, TEMPSENSE0 + REG_SET, alarm_value <<
TEMPSENSE0_ALARM_VALUE_SHIFT);
}

static int imx_get_temp(struct thermal_zone_device *tz, unsigned long *temp)
{
struct imx_thermal_data *data = tz->devdata;
struct regmap *map = data->tempmon;
static unsigned long last_temp;
unsigned int n_meas;
bool wait;
u32 val;

/*
* Every time we measure the temperature, we will power on the
* temperature sensor, enable measurements, take a reading,
* disable measurements, power off the temperature sensor.
*/
regmap_write(map, TEMPSENSE0 + REG_CLR, TEMPSENSE0_POWER_DOWN);
regmap_write(map, TEMPSENSE0 + REG_SET, TEMPSENSE0_MEASURE_TEMP);
if (data->mode == THERMAL_DEVICE_ENABLED) {
/* Check if a measurement is currently in progress */
regmap_read(map, TEMPSENSE0, &val);
wait = !(val & TEMPSENSE0_FINISHED);
} else {
/*
* Every time we measure the temperature, we will power on the
* temperature sensor, enable measurements, take a reading,
* disable measurements, power off the temperature sensor.
*/
regmap_write(map, TEMPSENSE0 + REG_CLR, TEMPSENSE0_POWER_DOWN);
regmap_write(map, TEMPSENSE0 + REG_SET, TEMPSENSE0_MEASURE_TEMP);

wait = true;
}

/*
* According to the temp sensor designers, it may require up to ~17us
* to complete a measurement.
*/
usleep_range(20, 50);
if (wait)
usleep_range(20, 50);

regmap_read(map, TEMPSENSE0, &val);
regmap_write(map, TEMPSENSE0 + REG_CLR, TEMPSENSE0_MEASURE_TEMP);
regmap_write(map, TEMPSENSE0 + REG_SET, TEMPSENSE0_POWER_DOWN);

if (data->mode != THERMAL_DEVICE_ENABLED) {
regmap_write(map, TEMPSENSE0 + REG_CLR, TEMPSENSE0_MEASURE_TEMP);
regmap_write(map, TEMPSENSE0 + REG_SET, TEMPSENSE0_POWER_DOWN);
}

if ((val & TEMPSENSE0_FINISHED) == 0) {
dev_dbg(&tz->device, "temp measurement never finished\n");
Expand All @@ -104,9 +136,24 @@ static int imx_get_temp(struct thermal_zone_device *tz, unsigned long *temp)
/* See imx_get_sensor_data() for formula derivation */
*temp = data->c2 + data->c1 * n_meas;

if (*temp != last_temp) {
/* Update alarm value to next higher trip point */
if (data->alarm_temp == data->temp_passive && *temp >= data->temp_passive)
imx_set_alarm_temp(data, data->temp_critical);
if (data->alarm_temp == data->temp_critical && *temp < data->temp_passive) {
imx_set_alarm_temp(data, data->temp_passive);
dev_dbg(&tz->device, "thermal alarm off: T < %lu\n",
data->alarm_temp / 1000);
}

if (*temp != data->last_temp) {
dev_dbg(&tz->device, "millicelsius: %ld\n", *temp);
last_temp = *temp;
data->last_temp = *temp;
}

/* Reenable alarm IRQ if temperature below alarm temperature */
if (!data->irq_enabled && *temp < data->alarm_temp) {
data->irq_enabled = true;
enable_irq(data->irq);
}

return 0;
Expand All @@ -126,13 +173,30 @@ static int imx_set_mode(struct thermal_zone_device *tz,
enum thermal_device_mode mode)
{
struct imx_thermal_data *data = tz->devdata;
struct regmap *map = data->tempmon;

if (mode == THERMAL_DEVICE_ENABLED) {
tz->polling_delay = IMX_POLLING_DELAY;
tz->passive_delay = IMX_PASSIVE_DELAY;

regmap_write(map, TEMPSENSE0 + REG_CLR, TEMPSENSE0_POWER_DOWN);
regmap_write(map, TEMPSENSE0 + REG_SET, TEMPSENSE0_MEASURE_TEMP);

if (!data->irq_enabled) {
data->irq_enabled = true;
enable_irq(data->irq);
}
} else {
regmap_write(map, TEMPSENSE0 + REG_CLR, TEMPSENSE0_MEASURE_TEMP);
regmap_write(map, TEMPSENSE0 + REG_SET, TEMPSENSE0_POWER_DOWN);

tz->polling_delay = 0;
tz->passive_delay = 0;

if (data->irq_enabled) {
disable_irq(data->irq);
data->irq_enabled = false;
}
}

data->mode = mode;
Expand Down Expand Up @@ -181,6 +245,8 @@ static int imx_set_trip_temp(struct thermal_zone_device *tz, int trip,

data->temp_passive = temp;

imx_set_alarm_temp(data, temp);

return 0;
}

Expand Down Expand Up @@ -299,11 +365,34 @@ static int imx_get_sensor_data(struct platform_device *pdev)
return 0;
}

static irqreturn_t imx_thermal_alarm_irq(int irq, void *dev)
{
struct imx_thermal_data *data = dev;

disable_irq_nosync(irq);
data->irq_enabled = false;

return IRQ_WAKE_THREAD;
}

static irqreturn_t imx_thermal_alarm_irq_thread(int irq, void *dev)
{
struct imx_thermal_data *data = dev;

dev_dbg(&data->tz->device, "THERMAL ALARM: T > %lu\n",
data->alarm_temp / 1000);

thermal_zone_device_update(data->tz);

return IRQ_HANDLED;
}

static int imx_thermal_probe(struct platform_device *pdev)
{
struct imx_thermal_data *data;
struct cpumask clip_cpus;
struct regmap *map;
int measure_freq;
int ret;

data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
Expand All @@ -318,6 +407,18 @@ static int imx_thermal_probe(struct platform_device *pdev)
}
data->tempmon = map;

data->irq = platform_get_irq(pdev, 0);
if (data->irq < 0)
return data->irq;

ret = devm_request_threaded_irq(&pdev->dev, data->irq,
imx_thermal_alarm_irq, imx_thermal_alarm_irq_thread,
0, "imx_thermal", data);
if (ret < 0) {
dev_err(&pdev->dev, "failed to request alarm irq: %d\n", ret);
return ret;
}

platform_set_drvdata(pdev, data);

ret = imx_get_sensor_data(pdev);
Expand Down Expand Up @@ -356,6 +457,15 @@ static int imx_thermal_probe(struct platform_device *pdev)
return ret;
}

/* Enable measurements at ~ 10 Hz */
regmap_write(map, TEMPSENSE1 + REG_CLR, TEMPSENSE1_MEASURE_FREQ);
measure_freq = DIV_ROUND_UP(32768, 10); /* 10 Hz */
regmap_write(map, TEMPSENSE1 + REG_SET, measure_freq);
imx_set_alarm_temp(data, data->temp_passive);
regmap_write(map, TEMPSENSE0 + REG_CLR, TEMPSENSE0_POWER_DOWN);
regmap_write(map, TEMPSENSE0 + REG_SET, TEMPSENSE0_MEASURE_TEMP);

data->irq_enabled = true;
data->mode = THERMAL_DEVICE_ENABLED;

return 0;
Expand All @@ -364,6 +474,10 @@ static int imx_thermal_probe(struct platform_device *pdev)
static int imx_thermal_remove(struct platform_device *pdev)
{
struct imx_thermal_data *data = platform_get_drvdata(pdev);
struct regmap *map = data->tempmon;

/* Disable measurements */
regmap_write(map, TEMPSENSE0 + REG_SET, TEMPSENSE0_POWER_DOWN);

thermal_zone_device_unregister(data->tz);
cpufreq_cooling_unregister(data->cdev);
Expand Down

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