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Subject[PATCH] hwmon: (lm75) Add a basic interrupt handler
Date
The LM75 interrupt cannot be masked in the device so an over-temperature
event can cause an interrupt that cannot be cleared.
Add an interrupt handler if an interrupt node exists in the DTS for an
LM75. The handler simply reads a device register to clear the interrupt
and returns.

Signed-off-by: Tony O'Brien <tony.obrien@alliedtelesis.co.nz>
Reviewed-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
---
drivers/hwmon/lm75.c | 28 ++++++++++++++++++++++++++++
drivers/hwmon/lm75.h | 1 +
2 files changed, 29 insertions(+)

diff --git a/drivers/hwmon/lm75.c b/drivers/hwmon/lm75.c
index 005ffb5ffa92..08a833e960aa 100644
--- a/drivers/hwmon/lm75.c
+++ b/drivers/hwmon/lm75.c
@@ -22,6 +22,7 @@
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/jiffies.h>
+#include <linux/interrupt.h>
#include <linux/i2c.h>
#include <linux/hwmon.h>
#include <linux/hwmon-sysfs.h>
@@ -265,6 +266,17 @@ static void lm75_remove(void *data)
i2c_smbus_write_byte_data(client, LM75_REG_CONF, lm75->orig_conf);
}

+static irqreturn_t lm75_process_interrupt(int irq, void *data)
+{
+ struct i2c_client *client = (struct i2c_client *)data;
+ int val;
+
+ /* Do a read to clear the interrupt */
+ val = i2c_smbus_read_byte_data(client, LM75_REG_CONF);
+
+ return IRQ_HANDLED;
+}
+
static int
lm75_probe(struct i2c_client *client, const struct i2c_device_id *id)
{
@@ -275,6 +287,7 @@ lm75_probe(struct i2c_client *client, const struct i2c_device_id *id)
u8 set_mask, clr_mask;
int new;
enum lm75_type kind;
+ int ret;

if (client->dev.of_node)
kind = (enum lm75_type)of_device_get_match_data(&client->dev);
@@ -375,6 +388,21 @@ lm75_probe(struct i2c_client *client, const struct i2c_device_id *id)
break;
}

+ if (client->irq) {
+ /* If requesting an interrupt then set to interrupt mode */
+ set_mask |= LM75_MODE_INTERRUPT;
+ ret = devm_request_threaded_irq(dev, client->irq, NULL,
+ lm75_process_interrupt,
+ IRQF_TRIGGER_LOW | IRQF_ONESHOT |
+ IRQF_SHARED,
+ dev_name(dev),
+ client);
+ if (ret) {
+ dev_err(dev, "Error requesting irq\n");
+ return ret;
+ }
+ }
+
/* configure as specified */
status = i2c_smbus_read_byte_data(client, LM75_REG_CONF);
if (status < 0) {
diff --git a/drivers/hwmon/lm75.h b/drivers/hwmon/lm75.h
index 5cde94e56f17..82a71d870331 100644
--- a/drivers/hwmon/lm75.h
+++ b/drivers/hwmon/lm75.h
@@ -31,6 +31,7 @@
#define LM75_TEMP_MIN (-55000)
#define LM75_TEMP_MAX 125000
#define LM75_SHUTDOWN 0x01
+#define LM75_MODE_INTERRUPT 0x02

/* TEMP: 0.001C/bit (-55C to +125C)
REG: (0.5C/bit, two's complement) << 7 */
--
2.13.0
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