[RFC PATCH 3/9] hwmon: (lm90) add support to handle irq

[Wei Ni]

Add support to handle irq. When the temperature touch the limit value, the
driver can handle the interrupt.

Signed-off-by: Alexandre Courbot <acourbot at nvidia.com>
Signed-off-by: Wei Ni <wni at nvidia.com>
---
 drivers/hwmon/lm90.c |   38 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)

diff --git a/drivers/hwmon/lm90.c b/drivers/hwmon/lm90.c
index caf01b0..80311ef 100644
--- a/drivers/hwmon/lm90.c
+++ b/drivers/hwmon/lm90.c
@@ -89,6 +89,8 @@
 #include <linux/err.h>
 #include <linux/mutex.h>
 #include <linux/sysfs.h>
+#include <linux/interrupt.h>
+#include <linux/of_irq.h>
 
 /*
  * Addresses to scan
@@ -302,6 +304,7 @@ static const struct lm90_params lm90_params[] = {
 struct lm90_data {
 	struct device *hwmon_dev;
 	struct mutex update_lock;
+	struct work_struct irq_work;
 	char valid; /* zero until following fields are valid */
 	unsigned long last_updated; /* in jiffies */
 	int kind;
@@ -1418,6 +1421,29 @@ static void lm90_init_client(struct i2c_client *client)
 		i2c_smbus_write_byte_data(client, LM90_REG_W_CONFIG1, config);
 }
 
+static void lm90_alert(struct i2c_client *client, unsigned int flag);
+
+static void lm90_irq_work(struct work_struct *work)
+{
+	struct lm90_data *data = container_of(work, struct lm90_data,
+					      irq_work);
+	struct i2c_client *client = to_i2c_client(data->hwmon_dev->parent);
+
+	lm90_alert(client, 0);
+
+	enable_irq(client->irq);
+}
+
+static irqreturn_t lm90_irq(int irq, void *dev_id)
+{
+	struct lm90_data *data = dev_id;
+
+	disable_irq_nosync(irq);
+	schedule_work(&data->irq_work);
+
+	return IRQ_HANDLED;
+}
+
 static int lm90_probe(struct i2c_client *client,
 		      const struct i2c_device_id *id)
 {
@@ -1494,6 +1520,17 @@ static int lm90_probe(struct i2c_client *client,
 		goto exit_remove_files;
 	}
 
+	if (client->irq >= 0) {
+		INIT_WORK(&data->irq_work, lm90_irq_work);
+		dev_dbg(dev, "lm90 irq: %d\n", client->irq);
+		err = request_irq(client->irq, lm90_irq, IRQF_TRIGGER_LOW,
+				       "lm90", data);
+		if (err < 0) {
+			dev_err(dev, "cannot request interrupt\n");
+			goto exit_remove_files;
+		}
+	}
+
 	return 0;
 
 exit_remove_files:
@@ -1507,6 +1544,7 @@ static int lm90_remove(struct i2c_client *client)
 {
 	struct lm90_data *data = i2c_get_clientdata(client);
 
+	free_irq(client->irq, data);
 	hwmon_device_unregister(data->hwmon_dev);
 	lm90_remove_files(client, data);
 	lm90_restore_conf(client, data);
-- 
1.7.9.5