greybus: battery: update for 4.1 power supply api changes

The 4.1-rc1 kernel changed the power supply apis such that the
structures are now owned by the power supply core, and not the
individual drivers.  This broke the greybus battery driver, so update it
to support both the old and the new apis.

The API changes were such that I can't "hide" them in kernel_ver.h, but
rather the driver itself needs to have ugly #ifdefs in it.  I tried to
keep it to a minimum, making a sub-function for initializing the power
supply device that is implemented differently for different kernel
versions.

When this is submitted upstream, or if we ever move our AP development
to 4.1 or greater, the support for older kernels can be removed.
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Reviewed-by: Viresh Kumar <viresh.kumar@linaro.org>

drivers/staging/greybus/battery.c

@@ -7,6 +7,7 @@
  * Released under the GPLv2 only.
  */
 
+#include <linux/version.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/slab.h>
@@ -14,7 +15,19 @@
 #include "greybus.h"
 
 struct gb_battery {
+	/*
+	 * The power supply api changed in 4.1, so handle both the old
+	 * and new apis in the same driver for now, until this is merged
+	 * upstream, when all of these version checks can be removed.
+	 */
+#if LINUX_VERSION_CODE < KERNEL_VERSION(4, 1, 0)
 	struct power_supply bat;
+#define to_gb_battery(x) container_of(x, struct gb_battery, bat)
+#else
+	struct power_supply *bat;
+	struct power_supply_desc desc;
+#define to_gb_battery(x) power_supply_get_drvdata(x)
+#endif
 	// FIXME
 	// we will want to keep the battery stats in here as we will be getting
 	// updates from the SVC "on the fly" so we don't have to always go ask
@@ -24,7 +37,6 @@ struct gb_battery {
 	u8 version_minor;
 
 };
-#define to_gb_battery(x) container_of(x, struct gb_battery, bat)
 
 /* Version of the Greybus battery protocol we support */
 #define	GB_BATTERY_VERSION_MAJOR		0x00
@@ -283,10 +295,56 @@ static enum power_supply_property battery_props[] = {
 	POWER_SUPPLY_PROP_VOLTAGE_NOW,
 };
 
+#if LINUX_VERSION_CODE < KERNEL_VERSION(4, 1, 0)
+static int init_and_register(struct gb_connection *connection,
+			     struct gb_battery *gb)
+{
+	int retval;
+
+	// FIXME - get a better (i.e. unique) name
+	// FIXME - anything else needs to be set?
+	gb->bat.name		= "gb_battery";
+	gb->bat.type		= POWER_SUPPLY_TYPE_BATTERY;
+	gb->bat.properties	= battery_props;
+	gb->bat.num_properties	= ARRAY_SIZE(battery_props);
+	gb->bat.get_property	= get_property;
+
+	retval = power_supply_register(&connection->bundle->intf->dev,
+				       &gb->bat);
+	if (retval)
+		kfree(gb);
+	return retval;
+}
+#else
+static int init_and_register(struct gb_connection *connection,
+			     struct gb_battery *gb)
+{
+	struct power_supply_config cfg = {};
+	int retval = 0;
+
+	cfg.drv_data = gb;
+
+	// FIXME - get a better (i.e. unique) name
+	// FIXME - anything else needs to be set?
+	gb->desc.name		= "gb_battery";
+	gb->desc.type		= POWER_SUPPLY_TYPE_BATTERY;
+	gb->desc.properties	= battery_props;
+	gb->desc.num_properties	= ARRAY_SIZE(battery_props);
+	gb->desc.get_property	= get_property;
+
+	gb->bat = power_supply_register(&connection->bundle->intf->dev,
+					&gb->desc, &cfg);
+	if (IS_ERR(gb->bat)) {
+		retval = PTR_ERR(gb->bat);
+		kfree(gb);
+	}
+	return retval;
+}
+#endif
+
 static int gb_battery_connection_init(struct gb_connection *connection)
 {
 	struct gb_battery *gb;
-	struct power_supply *b;
 	int retval;
 
 	gb = kzalloc(sizeof(*gb), GFP_KERNEL);
@@ -303,29 +361,18 @@ static int gb_battery_connection_init(struct gb_connection *connection)
 		return retval;
 	}
 
-	b = &gb->bat;
-	// FIXME - get a better (i.e. unique) name
-	// FIXME - anything else needs to be set?
-	b->name			= "gb_battery";
-	b->type			= POWER_SUPPLY_TYPE_BATTERY,
-	b->properties		= battery_props,
-	b->num_properties	= ARRAY_SIZE(battery_props),
-	b->get_property		= get_property,
-
-	retval = power_supply_register(&connection->bundle->intf->dev, b);
-	if (retval) {
-		kfree(gb);
-		return retval;
-	}
-
-	return 0;
+	return init_and_register(connection, gb);
 }
 
 static void gb_battery_connection_exit(struct gb_connection *connection)
 {
 	struct gb_battery *gb = connection->private;
 
+#if LINUX_VERSION_CODE < KERNEL_VERSION(4, 1, 0)
 	power_supply_unregister(&gb->bat);
+#else
+	power_supply_unregister(gb->bat);
+#endif
 	kfree(gb);
 }