power: bq27xxx_battery: allow kernel poll_interval parameter runtime update

drivers/power/bq27xxx_battery.c

@@ -39,6 +39,7 @@
 
 #include <linux/device.h>
 #include <linux/module.h>
+#include <linux/mutex.h>
 #include <linux/param.h>
 #include <linux/jiffies.h>
 #include <linux/workqueue.h>
@@ -402,8 +403,35 @@ static struct {
 	BQ27XXX_PROP(BQ27421, bq27421_battery_props),
 };
 
+static DEFINE_MUTEX(bq27xxx_list_lock);
+static LIST_HEAD(bq27xxx_battery_devices);
+
+static int poll_interval_param_set(const char *val, const struct kernel_param *kp)
+{
+	struct bq27xxx_device_info *di;
+	int ret;
+
+	ret = param_set_uint(val, kp);
+	if (ret < 0)
+		return ret;
+
+	mutex_lock(&bq27xxx_list_lock);
+	list_for_each_entry(di, &bq27xxx_battery_devices, list) {
+		cancel_delayed_work_sync(&di->work);
+		schedule_delayed_work(&di->work, 0);
+	}
+	mutex_unlock(&bq27xxx_list_lock);
+
+	return ret;
+}
+
+static const struct kernel_param_ops param_ops_poll_interval = {
+	.get = param_get_uint,
+	.set = poll_interval_param_set,
+};
+
 static unsigned int poll_interval = 360;
-module_param(poll_interval, uint, 0644);
+module_param_cb(poll_interval, &param_ops_poll_interval, &poll_interval, 0644);
 MODULE_PARM_DESC(poll_interval,
 		 "battery poll interval in seconds - 0 disables polling");
 
@@ -986,6 +1014,10 @@ int bq27xxx_battery_setup(struct bq27xxx_device_info *di)
 
 	bq27xxx_battery_update(di);
 
+	mutex_lock(&bq27xxx_list_lock);
+	list_add(&di->list, &bq27xxx_battery_devices);
+	mutex_unlock(&bq27xxx_list_lock);
+
 	return 0;
 }
 EXPORT_SYMBOL_GPL(bq27xxx_battery_setup);
@@ -1004,6 +1036,10 @@ void bq27xxx_battery_teardown(struct bq27xxx_device_info *di)
 
 	power_supply_unregister(di->bat);
 
+	mutex_lock(&bq27xxx_list_lock);
+	list_del(&di->list);
+	mutex_unlock(&bq27xxx_list_lock);
+
 	mutex_destroy(&di->lock);
 }
 EXPORT_SYMBOL_GPL(bq27xxx_battery_teardown);

include/linux/power/bq27xxx_battery.h

@@ -58,6 +58,7 @@ struct bq27xxx_device_info {
 	unsigned long last_update;
 	struct delayed_work work;
 	struct power_supply *bat;
+	struct list_head list;
 	struct mutex lock;
 	u8 *regs;
 };