Add threshold alarm support for the max31722 temperature sensor driver.
Signed-off-by: Tiberiu Breana <tiberiu.a.breana@xxxxxxxxx>
---
Changes from v2:
- addressed Guenter's comments
- improved threshold value precision
- threshold values are now cached
---
drivers/hwmon/max31722.c | 158 +++++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 153 insertions(+), 5 deletions(-)
diff --git a/drivers/hwmon/max31722.c b/drivers/hwmon/max31722.c
index 30a100e..1460b22 100644
--- a/drivers/hwmon/max31722.c
+++ b/drivers/hwmon/max31722.c
@@ -12,23 +12,37 @@
#include <linux/acpi.h>
#include <linux/hwmon.h>
#include <linux/hwmon-sysfs.h>
+#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/spi/spi.h>
#define MAX31722_REG_CFG 0x00
#define MAX31722_REG_TEMP_LSB 0x01
+#define MAX31722_REG_THIGH_LSB 0x03
+#define MAX31722_REG_TLOW_LSB 0x05
#define MAX31722_MODE_CONTINUOUS 0x00
#define MAX31722_MODE_STANDBY 0x01
#define MAX31722_MODE_MASK 0xFE
#define MAX31722_RESOLUTION_12BIT 0x06
+#define MAX31722_TM_INTERRUPT 0x08
#define MAX31722_WRITE_MASK 0x80
+/*
+ * Minimum temperature value: -2^(12-1) * 62.5 = -128,000
+ * Maximum temperature value: (2^(12-1) - 1) * 62.5 ~= 127,937
+ */
+#define MAX31722_MIN_TEMP -128000
+#define MAX31722_MAX_TEMP 127937
struct max31722_data {
struct device *hwmon_dev;
struct spi_device *spi_device;
u8 mode;
+ s16 thigh;
+ s16 tlow;
+ bool irq_enabled;
+ bool alarm_active;
};
static int max31722_set_mode(struct max31722_data *data, u8 mode)
@@ -56,23 +70,139 @@ static ssize_t max31722_show_temp(struct device *dev,
{
ssize_t ret;
struct max31722_data *data = dev_get_drvdata(dev);
+ struct sensor_device_attribute *dev_attr = to_sensor_dev_attr(attr);
- ret = spi_w8r16(data->spi_device, MAX31722_REG_TEMP_LSB);
+ ret = spi_w8r16(data->spi_device, dev_attr->index);
if (ret < 0)
return ret;
/* Keep 12 bits and multiply by the scale of 62.5 millidegrees/bit. */
return sprintf(buf, "%d\n", (s16)le16_to_cpu(ret) * 125 / 32);
}
-static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO,
- max31722_show_temp, NULL, 0);
+static ssize_t max31722_set_temp(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ int ret;
+ long val;
+ s16 thresh;
+ u8 tx_buf[3];
+ struct max31722_data *data = dev_get_drvdata(dev);
+ struct sensor_device_attribute *dev_attr = to_sensor_dev_attr(attr);
+
+ ret = kstrtol(buf, 10, &val);
+ if (ret < 0)
+ return ret;
+
+ val = clamp_val(val, MAX31722_MIN_TEMP, MAX31722_MAX_TEMP);
+ thresh = cpu_to_le16(DIV_ROUND_CLOSEST(val * 32, 125));
+
+ tx_buf[0] = dev_attr->index | MAX31722_WRITE_MASK;
+ tx_buf[1] = thresh & 0xff;
+ tx_buf[2] = thresh >> 8;
+ ret = spi_write(data->spi_device, &tx_buf, sizeof(tx_buf));
+ if (ret < 0)
+ return ret;
+
+ if (dev_attr->index == 1)
+ data->thigh = thresh;
+ else if (dev_attr->index == 2)
+ data->tlow = thresh;
+
+ 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);
+}
+
+static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, max31722_show_temp, NULL,
+ MAX31722_REG_TEMP_LSB);
+static SENSOR_DEVICE_ATTR(temp1_max, S_IWUSR | S_IRUGO, max31722_show_temp,
+ max31722_set_temp, MAX31722_REG_THIGH_LSB);
+static SENSOR_DEVICE_ATTR(temp1_max_hyst, S_IWUSR | S_IRUGO, max31722_show_temp,
+ max31722_set_temp, MAX31722_REG_TLOW_LSB);
+static DEVICE_ATTR(temp1_alarm, S_IRUGO, max31722_show_alarm, NULL);
static struct attribute *max31722_attrs[] = {
&sensor_dev_attr_temp1_input.dev_attr.attr,
+ &sensor_dev_attr_temp1_max.dev_attr.attr,
+ &sensor_dev_attr_temp1_max_hyst.dev_attr.attr,
+ &dev_attr_temp1_alarm.attr,
NULL,
};
-ATTRIBUTE_GROUPS(max31722);
+static umode_t max31722_is_visible(struct kobject *kobj, struct attribute *attr,
+ int index)
+{
+ struct device *dev = container_of(kobj, struct device, kobj);
+ struct max31722_data *data = dev_get_drvdata(dev);
+
+ /* Hide the alarm attribute if interrupts are disabled. */
+ if (!data->irq_enabled && index == 3)
+ return 0;
+
+ return attr->mode;
+}
+
+static const struct attribute_group max31722_group = {
+ .attrs = max31722_attrs, .is_visible = max31722_is_visible,
+};
+
+__ATTRIBUTE_GROUPS(max31722);
+
+static void max31722_update_alarm(struct max31722_data *data)
+{
+ s16 temp;
+ ssize_t ret;
+ /*
+ * Do a quick temperature reading and compare it with TLOW/THIGH
+ * so we can tell which threshold has been met.
+ */
+ ret = spi_w8r16(data->spi_device, MAX31722_REG_TEMP_LSB);
+ if (ret < 0)
+ goto exit_err;
+ temp = (s16)ret;
+ if (!data->tlow) {
+ ret = spi_w8r16(data->spi_device, MAX31722_REG_TLOW_LSB);
+ if (ret < 0)
+ goto exit_err;
+ data->tlow = (s16)ret;
+ }
+ if (!data->thigh) {
+ ret = spi_w8r16(data->spi_device, MAX31722_REG_THIGH_LSB);
+ if (ret < 0)
+ goto exit_err;
+ data->thigh = (s16)ret;
+ }
+
+ if (temp > data->thigh || (!data->alarm_active && temp > data->tlow))
+ data->alarm_active = true;
+ else if (temp <= data->tlow ||
+ (data->alarm_active && temp < data->thigh))
+ data->alarm_active = false;
+
+ sysfs_notify(&data->spi_device->dev.kobj, NULL, "temp1_alarm");
+ return;
+
+exit_err:
+ dev_err(&data->spi_device->dev, "failed to read temperature register\n");
+}
+
+static irqreturn_t max31722_irq_handler(int irq, void *private)
+{
+ struct max31722_data *data = private;
+
+ max31722_update_alarm(data);
+
+ return IRQ_HANDLED;
+}
static int max31722_probe(struct spi_device *spi)
{
@@ -89,11 +219,29 @@ static int max31722_probe(struct spi_device *spi)
* Set SD bit to 0 so we can have continuous measurements.
* Set resolution to 12 bits for maximum precision.
*/
- data->mode = MAX31722_MODE_CONTINUOUS | MAX31722_RESOLUTION_12BIT;
+ data->mode = MAX31722_MODE_CONTINUOUS | MAX31722_RESOLUTION_12BIT
+ | MAX31722_TM_INTERRUPT;
ret = max31722_set_mode(data, MAX31722_MODE_CONTINUOUS);
if (ret < 0)
return ret;
+ data->irq_enabled = false;
+ 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_warn(&spi->dev, "request irq %d failed\n",
+ spi->irq);
+ } else {
+ data->irq_enabled = true;
+ data->alarm_active = false;
+ max31722_update_alarm(data);
+ }
+ }
+
data->hwmon_dev = hwmon_device_register_with_groups(&spi->dev,
spi->modalias,
data,
--
1.9.1
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