i2c: core: support bus regulator controlling in adapter

Although in the most platforms, the bus power of i2c
are alway on, some platforms disable the i2c bus power
in order to meet low power request.

We get and enable bulk regulator in i2c adapter device.
Signed-off-by: Bibby Hsieh <bibby.hsieh@mediatek.com>
Reviewed-by: Tomasz Figa <tfiga@chromium.org>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

drivers/i2c/i2c-core-base.c

@@ -313,12 +313,14 @@ static int i2c_smbus_host_notify_to_irq(const struct i2c_client *client)
 static int i2c_device_probe(struct device *dev)
 {
 	struct i2c_client	*client = i2c_verify_client(dev);
+	struct i2c_adapter	*adap;
 	struct i2c_driver	*driver;
 	int status;
 
 	if (!client)
 		return 0;
 
+	adap = client->adapter;
 	driver = to_i2c_driver(dev->driver);
 
 	client->irq = client->init_irq;
@@ -378,6 +380,12 @@ static int i2c_device_probe(struct device *dev)
 
 	dev_dbg(dev, "probe\n");
 
+	status = regulator_enable(adap->bus_regulator);
+	if (status < 0) {
+		dev_err(&adap->dev, "Failed to enable power regulator\n");
+		goto err_clear_wakeup_irq;
+	}
+
 	status = of_clk_set_defaults(dev->of_node, false);
 	if (status < 0)
 		goto err_clear_wakeup_irq;
@@ -414,12 +422,14 @@ static int i2c_device_probe(struct device *dev)
 static int i2c_device_remove(struct device *dev)
 {
 	struct i2c_client	*client = i2c_verify_client(dev);
+	struct i2c_adapter      *adap;
 	struct i2c_driver	*driver;
 	int status = 0;
 
 	if (!client || !dev->driver)
 		return 0;
 
+	adap = client->adapter;
 	driver = to_i2c_driver(dev->driver);
 	if (driver->remove) {
 		dev_dbg(dev, "remove\n");
@@ -427,6 +437,8 @@ static int i2c_device_remove(struct device *dev)
 	}
 
 	dev_pm_domain_detach(&client->dev, true);
+	if (!pm_runtime_status_suspended(&client->dev))
+		regulator_disable(adap->bus_regulator);
 
 	dev_pm_clear_wake_irq(&client->dev);
 	device_init_wakeup(&client->dev, false);
@@ -438,6 +450,72 @@ static int i2c_device_remove(struct device *dev)
 	return status;
 }
 
+#ifdef CONFIG_PM_SLEEP
+static int i2c_resume_early(struct device *dev)
+{
+	struct i2c_client *client = i2c_verify_client(dev);
+	struct i2c_adapter *adap = client->adapter;
+	int err;
+
+	if (!pm_runtime_status_suspended(&client->dev)) {
+		err = regulator_enable(adap->bus_regulator);
+		if (err)
+			return err;
+	}
+
+	return pm_generic_resume_early(&client->dev);
+}
+
+static int i2c_suspend_late(struct device *dev)
+{
+	struct i2c_client *client = i2c_verify_client(dev);
+	struct i2c_adapter *adap = client->adapter;
+	int err;
+
+	err = pm_generic_suspend_late(&client->dev);
+	if (err)
+		return err;
+
+	if (!pm_runtime_status_suspended(&client->dev))
+		return regulator_disable(adap->bus_regulator);
+
+	return 0;
+}
+#endif
+
+#ifdef CONFIG_PM
+static int i2c_runtime_resume(struct device *dev)
+{
+	struct i2c_client *client = i2c_verify_client(dev);
+	struct i2c_adapter *adap = client->adapter;
+	int err;
+
+	err = regulator_enable(adap->bus_regulator);
+	if (err)
+		return err;
+
+	return pm_generic_runtime_resume(&client->dev);
+}
+
+static int i2c_runtime_suspend(struct device *dev)
+{
+	struct i2c_client *client = i2c_verify_client(dev);
+	struct i2c_adapter *adap = client->adapter;
+	int err;
+
+	err = pm_generic_runtime_suspend(&client->dev);
+	if (err)
+		return err;
+
+	return regulator_disable(adap->bus_regulator);
+}
+#endif
+
+static const struct dev_pm_ops i2c_device_pm = {
+	SET_LATE_SYSTEM_SLEEP_PM_OPS(i2c_suspend_late, i2c_resume_early)
+	SET_RUNTIME_PM_OPS(i2c_runtime_suspend, i2c_runtime_resume, NULL)
+};
+
 static void i2c_device_shutdown(struct device *dev)
 {
 	struct i2c_client *client = i2c_verify_client(dev);
@@ -495,6 +573,7 @@ struct bus_type i2c_bus_type = {
 	.probe		= i2c_device_probe,
 	.remove		= i2c_device_remove,
 	.shutdown	= i2c_device_shutdown,
+	.pm		= &i2c_device_pm,
 };
 EXPORT_SYMBOL_GPL(i2c_bus_type);
 
@@ -1333,6 +1412,11 @@ static int i2c_register_adapter(struct i2c_adapter *adap)
 	if (res)
 		goto out_reg;
 
+	adap->bus_regulator = devm_regulator_get(&adap->dev, "bus");
+	if (IS_ERR(adap->bus_regulator)) {
+		res = PTR_ERR(adap->bus_regulator);
+		goto out_reg;
+	}
 	dev_dbg(&adap->dev, "adapter [%s] registered\n", adap->name);
 
 	pm_runtime_no_callbacks(&adap->dev);

include/linux/i2c.h

@@ -15,6 +15,7 @@
 #include <linux/device.h>	/* for struct device */
 #include <linux/sched.h>	/* for completion */
 #include <linux/mutex.h>
+#include <linux/regulator/consumer.h>
 #include <linux/rtmutex.h>
 #include <linux/irqdomain.h>		/* for Host Notify IRQ */
 #include <linux/of.h>		/* for struct device_node */
@@ -721,6 +722,7 @@ struct i2c_adapter {
 	const struct i2c_adapter_quirks *quirks;
 
 	struct irq_domain *host_notify_domain;
+	struct regulator *bus_regulator;
 };
 #define to_i2c_adapter(d) container_of(d, struct i2c_adapter, dev)