i2c: i2c-smbus: add of_i2c_setup_smbus_alert

This commit adds of_i2c_setup_smbus_alert which allows the smbalert
driver to be attached to an i2c adapter via the device tree.

Signed-off-by: Phil Reid <[e-mail]>
Acked-by: Rob Herring <[e-mail]>
Signed-off-by: Wolfram Sang <[e-mail]>

Documentation/devicetree/bindings/i2c/i2c.txt

···
 	interrupts used by the device.
 
 - interrupt-names
-	"irq" and "wakeup" names are recognized by I2C core, other names are
-	left to individual drivers.
+	"irq", "wakeup" and "smbus_alert" names are recognized by I2C core,
+	other names are	left to individual drivers.
 
 - host-notify
 	device uses SMBus host notify protocol instead of interrupt line.

drivers/i2c/i2c-core-smbus.c

···
 	return i2c_new_device(adapter, &ara_board_info);
 }
 EXPORT_SYMBOL_GPL(i2c_setup_smbus_alert);
+
+#if IS_ENABLED(CONFIG_I2C_SMBUS) && IS_ENABLED(CONFIG_OF)
+int of_i2c_setup_smbus_alert(struct i2c_adapter *adapter)
+{
+	struct i2c_client *client;
+	int irq;
+
+	irq = of_property_match_string(adapter->dev.of_node, "interrupt-names",
+				       "smbus_alert");
+	if (irq == -EINVAL || irq == -ENODATA)
+		return 0;
+	else if (irq < 0)
+		return irq;
+
+	client = i2c_setup_smbus_alert(adapter, NULL);
+	if (!client)
+		return -ENODEV;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(of_i2c_setup_smbus_alert);
+#endif

drivers/i2c/i2c-smbus.c

···
 #include <linux/interrupt.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
+#include <linux/of_irq.h>
 #include <linux/slab.h>
 #include <linux/workqueue.h>
 
···
 	if (!alert)
 		return -ENOMEM;
 
-	irq = setup->irq;
+	if (setup) {
+		irq = setup->irq;
+	} else {
+		irq = of_irq_get_byname(adapter->dev.of_node, "smbus_alert");
+		if (irq <= 0)
+			return irq;
+	}
+
 	INIT_WORK(&alert->alert, smbalert_work);
 	alert->ara = ara;
 

include/linux/i2c-smbus.h

···
 					 struct i2c_smbus_alert_setup *setup);
 int i2c_handle_smbus_alert(struct i2c_client *ara);
 
+#if IS_ENABLED(CONFIG_I2C_SMBUS) && IS_ENABLED(CONFIG_OF)
+int of_i2c_setup_smbus_alert(struct i2c_adapter *adap);
+#else
+static inline int of_i2c_setup_smbus_alert(struct i2c_adapter *adap)
+{
+	return 0;
+}
+#endif
+
 #endif /* _LINUX_I2C_SMBUS_H */