i2c-core: i2c bus should support PM entries in struct dev_pm_ops

Struct dev_pm_ops is not configured in current i2c bus type. i2c drivers
only depends on suspend/resume entries in struct dev_pm_ops are not
informed of PM suspend and resume events by i2c framework.
Signed-off-by: Sonic Zhang <sonic.zhang@analog.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>

drivers/i2c/i2c-core.c

@@ -155,6 +155,35 @@ static void i2c_device_shutdown(struct device *dev)
 		driver->shutdown(client);
 }
 
+#ifdef CONFIG_SUSPEND
+static int i2c_device_pm_suspend(struct device *dev)
+{
+	const struct dev_pm_ops *pm;
+
+	if (!dev->driver)
+		return 0;
+	pm = dev->driver->pm;
+	if (!pm || !pm->suspend)
+		return 0;
+	return pm->suspend(dev);
+}
+
+static int i2c_device_pm_resume(struct device *dev)
+{
+	const struct dev_pm_ops *pm;
+
+	if (!dev->driver)
+		return 0;
+	pm = dev->driver->pm;
+	if (!pm || !pm->resume)
+		return 0;
+	return pm->resume(dev);
+}
+#else
+#define i2c_device_pm_suspend	NULL
+#define i2c_device_pm_resume	NULL
+#endif
+
 static int i2c_device_suspend(struct device *dev, pm_message_t mesg)
 {
 	struct i2c_client *client = i2c_verify_client(dev);
@@ -219,6 +248,11 @@ static const struct attribute_group *i2c_dev_attr_groups[] = {
 	NULL
 };
 
+const static struct dev_pm_ops i2c_device_pm_ops = {
+	.suspend = i2c_device_pm_suspend,
+	.resume = i2c_device_pm_resume,
+};
+
 struct bus_type i2c_bus_type = {
 	.name		= "i2c",
 	.match		= i2c_device_match,
@@ -227,6 +261,7 @@ struct bus_type i2c_bus_type = {
 	.shutdown	= i2c_device_shutdown,
 	.suspend	= i2c_device_suspend,
 	.resume		= i2c_device_resume,
+	.pm		= &i2c_device_pm_ops,
 };
 EXPORT_SYMBOL_GPL(i2c_bus_type);