Add temperature threshold alarm support for the max31722
sensor driver.
Signed-off-by: Tiberiu Breana <tiberiu.a.breana@xxxxxxxxx>
---
Documentation/hwmon/max31722 | 7 +++
drivers/hwmon/max31722.c | 130 +++++++++++++++++++++++++++++++++++++++++--
2 files changed, 131 insertions(+), 6 deletions(-)
diff --git a/Documentation/hwmon/max31722 b/Documentation/hwmon/max31722
index 090da845..e247963 100644
--- a/Documentation/hwmon/max31722
+++ b/Documentation/hwmon/max31722
@@ -25,6 +25,10 @@ Usage Notes
-----------
This driver uses ACPI to auto-detect devices. See ACPI IDs in the above section.
+The sensor supports a temperature alarm. This is set once the measured
+temperature goes above a user-set threshold (temp1_max) and will be cleared
+once the temperature goes below temp1_min. See the datasheet, page 9,
+"Comparator Mode" for details.
Sysfs entries
-------------
@@ -32,3 +36,6 @@ Sysfs entries
The following attribute is supported:
temp1_input Measured temperature. Read-only.
+temp1_alarm Temperature alarm. Read-only.
+temp1_min Minimum temperature threshold. Read-write.
+temp1_max Maximum temperature threshold. Read-write.
diff --git a/drivers/hwmon/max31722.c b/drivers/hwmon/max31722.c
index 13ba906..8e14eed 100644
--- a/drivers/hwmon/max31722.c
+++ b/drivers/hwmon/max31722.c
@@ -11,6 +11,8 @@
#include <linux/kernel.h>
#include <linux/acpi.h>
+#include <linux/gpio/consumer.h>
+#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/regmap.h>
#include <linux/spi/spi.h>
@@ -20,13 +22,20 @@
#define MAX31722_REG_CFG 0x00
#define MAX31722_REG_TEMP_LSB 0x01
#define MAX31722_REG_TEMP_MSB 0x02
+#define MAX31722_REG_THIGH_LSB 0x03
+#define MAX31722_REG_TLOW_LSB 0x05
#define MAX31722_MAX_REG 0x86
#define MAX31722_MODE_CONTINUOUS 0x00
#define MAX31722_MODE_STANDBY 0x01
#define MAX31722_RESOLUTION_11BIT 0x02
+/* Minimum and maximum supported temperatures, in millidegrees */
+#define MAX31722_MIN_TEMP -55000
+#define MAX31722_MAX_TEMP 125000
+
#define MAX31722_REGMAP_NAME "max31722_regmap"
+#define MAX31722_GPIO "max31722_gpio"
#define MAX31722_REGFIELD(name) \
do { \
@@ -39,12 +48,27 @@
} \
} while (0)
+enum attr_index {
+ t_input,
+ t_min,
+ t_max,
+ t_alarm,
+ t_num_regs
+};
+
+static const u8 max31722_regs[t_num_regs] = {
+ [t_input] = MAX31722_REG_TEMP_LSB,
+ [t_min] = MAX31722_REG_TLOW_LSB,
+ [t_max] = MAX31722_REG_THIGH_LSB,
+};
+
struct max31722_data {
struct spi_device *spi_device;
struct device *hwmon_dev;
struct regmap *regmap;
struct regmap_field *reg_state;
struct regmap_field *reg_resolution;
+ bool alarm_active;
};
/*
@@ -117,9 +141,9 @@ static ssize_t max31722_show_name(struct device *dev,
return sprintf(buf, "%s\n", to_spi_device(dev)->modalias);
}
-static ssize_t max31722_show_temperature(struct device *dev,
- struct device_attribute *attr,
- char *buf)
+static ssize_t max31722_show_temp(struct device *dev,
+ struct device_attribute *devattr,
+ char *buf)
{
int i;
int ret;
@@ -127,8 +151,10 @@ static ssize_t max31722_show_temperature(struct device *dev,
s16 val;
u16 temp;
struct max31722_data *data = dev_get_drvdata(dev);
+ struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
- ret = regmap_bulk_read(data->regmap, MAX31722_REG_TEMP_LSB, &temp, 2);
+ ret = regmap_bulk_read(data->regmap,
+ max31722_regs[attr->index], &temp, 2);
if (ret < 0) {
dev_err(&data->spi_device->dev,
"failed to read temperature register\n");
@@ -152,13 +178,79 @@ static ssize_t max31722_show_temperature(struct device *dev,
return sprintf(buf, "%d\n", val);
}
+static ssize_t max31722_set_temp(struct device *dev,
+ struct device_attribute *devattr,
+ const char *buf, size_t count)
+{
+ int i;
+ int ret;
+ int fract;
+ u16 thresh;
+ u8 lsb;
+ struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
+ long val;
+ struct max31722_data *data = dev_get_drvdata(dev);
+
+ ret = kstrtol(buf, 10, &val);
+ if (ret < 0)
+ return ret;
+
+ if (val < MAX31722_MIN_TEMP || val > MAX31722_MAX_TEMP)
+ return -EINVAL;
+ /*
+ * Convert input to a register value. First round down the value to one
+ * that can be represented in the 11 bit resolution.
+ */
+ val -= val % max31722_milli_table[2];
+
+ fract = val % 1000;
+
+ lsb = 0;
+ for (i = 0 ; i < ARRAY_SIZE(max31722_milli_table) && fract > 0; i++)
+ if (fract - max31722_milli_table[i] >= 0) {
+ fract -= max31722_milli_table[i];
+ lsb += 1 << (3 - i - 1);
+ }
+ lsb <<= 5;
+
+ thresh = (val / 1000) << 8 | lsb;
+ ret = regmap_bulk_write(data->regmap,
+ max31722_regs[attr->index], &thresh, 2);
+ if (ret < 0) {
+ dev_err(&data->spi_device->dev,
+ "failed to write threshold register\n");
+ return ret;
+ }
+
+ return count;
+}
+
+static ssize_t max31722_show_alarm(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ struct spi_device *spi_device = to_spi_device(dev);
+ struct max31722_data *data = spi_get_drvdata(spi_device);
+
+ return sprintf(buf, "%d\n", data->alarm_active ? 1 : 0);
+}
+
static DEVICE_ATTR(name, S_IRUGO, max31722_show_name, NULL);
-static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO,
- max31722_show_temperature, NULL, 0);
+static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, max31722_show_temp, NULL, 0);
+static SENSOR_DEVICE_ATTR(temp1_min, S_IWUSR | S_IRUGO, max31722_show_temp,
+ max31722_set_temp, t_min);
+static SENSOR_DEVICE_ATTR(temp1_max, S_IWUSR | S_IRUGO, max31722_show_temp,
+ max31722_set_temp, t_max);
+static SENSOR_DEVICE_ATTR(temp1_alarm, S_IRUGO, max31722_show_alarm, NULL,
+ t_alarm);
+
static struct attribute *max31722_attributes[] = {
&dev_attr_name.attr,
&sensor_dev_attr_temp1_input.dev_attr.attr,
+ &sensor_dev_attr_temp1_min.dev_attr.attr,
+ &sensor_dev_attr_temp1_max.dev_attr.attr,
+ &sensor_dev_attr_temp1_alarm.dev_attr.attr,
NULL,
};
@@ -166,6 +258,18 @@ static const struct attribute_group max31722_group = {
.attrs = max31722_attributes,
};
+static irqreturn_t max31722_irq_handler(int irq, void *private)
+{
+ struct max31722_data *data = private;
+ /*
+ * The device will issue cyclical interrupts when the
+ * THIGH/TLOW thresholds are met.
+ */
+ data->alarm_active = !data->alarm_active;
+
+ return IRQ_HANDLED;
+}
+
static int max31722_init(struct max31722_data *data)
{
int ret = 0;
@@ -196,6 +300,8 @@ static int max31722_init(struct max31722_data *data)
if (ret < 0)
goto err;
+ data->alarm_active = false;
+
return 0;
err:
@@ -223,6 +329,18 @@ static int max31722_probe(struct spi_device *spi)
if (ret < 0)
goto err_standby;
+ if (spi->irq > 0) {
+ ret = devm_request_threaded_irq(&spi->dev, spi->irq,
+ NULL,
+ max31722_irq_handler,
+ IRQF_TRIGGER_LOW | IRQF_ONESHOT,
+ dev_name(&spi->dev), data);
+ if (ret < 0) {
+ dev_err(&spi->dev, "request irq %d failed\n", spi->irq);
+ goto err_remove_group;
+ }
+ }
+
data->hwmon_dev = hwmon_device_register(&spi->dev);
if (IS_ERR(data->hwmon_dev)) {
ret = PTR_ERR(data->hwmon_dev);
--
1.9.1
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