HID: input: map battery system charging

HID descriptors with Battery System (0x85) Charging (0x44) usage are
ignored and POWER_SUPPLY_STATUS_DISCHARGING is always reported to user
space, even when the device is charging.

Map this usage and when it is reported set the right charging status.

In addition, add KUnit tests to make sure that the charging status is
correctly set and reported. They can be run with the usual command:

$ ./tools/testing/kunit/kunit.py run --kunitconfig=drivers/hid

Signed-off-by: José Expósito <[e-mail]>
Signed-off-by: Jiri Kosina <[e-mail]>

drivers/hid/.kunitconfig

···
 CONFIG_KUNIT=y
 CONFIG_USB=y
 CONFIG_USB_HID=y
+CONFIG_HID_BATTERY_STRENGTH=y
 CONFIG_HID_UCLOGIC=y
 CONFIG_HID_KUNIT_TEST=y

drivers/hid/Kconfig

···
 config HID_KUNIT_TEST
 	tristate "KUnit tests for HID" if !KUNIT_ALL_TESTS
 	depends on KUNIT=y
+	depends on HID_BATTERY_STRENGTH
 	depends on HID_UCLOGIC
 	default KUNIT_ALL_TESTS
 	help

drivers/hid/hid-input-test.c

···
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ *  HID to Linux Input mapping
+ *
+ *  Copyright (c) 2022 José Expósito <[e-mail]>
+ */
+
+#include <kunit/test.h>
+
+static void hid_test_input_set_battery_charge_status(struct kunit *test)
+{
+	struct hid_device *dev;
+	bool handled;
+
+	dev = kunit_kzalloc(test, sizeof(*dev), GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, dev);
+
+	handled = hidinput_set_battery_charge_status(dev, HID_DG_HEIGHT, 0);
+	KUNIT_EXPECT_FALSE(test, handled);
+	KUNIT_EXPECT_EQ(test, dev->battery_charge_status, POWER_SUPPLY_STATUS_UNKNOWN);
+
+	handled = hidinput_set_battery_charge_status(dev, HID_BAT_CHARGING, 0);
+	KUNIT_EXPECT_TRUE(test, handled);
+	KUNIT_EXPECT_EQ(test, dev->battery_charge_status, POWER_SUPPLY_STATUS_DISCHARGING);
+
+	handled = hidinput_set_battery_charge_status(dev, HID_BAT_CHARGING, 1);
+	KUNIT_EXPECT_TRUE(test, handled);
+	KUNIT_EXPECT_EQ(test, dev->battery_charge_status, POWER_SUPPLY_STATUS_CHARGING);
+}
+
+static void hid_test_input_get_battery_property(struct kunit *test)
+{
+	struct power_supply *psy;
+	struct hid_device *dev;
+	union power_supply_propval val;
+	int ret;
+
+	dev = kunit_kzalloc(test, sizeof(*dev), GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, dev);
+	dev->battery_avoid_query = true;
+
+	psy = kunit_kzalloc(test, sizeof(*psy), GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, psy);
+	psy->drv_data = dev;
+
+	dev->battery_status = HID_BATTERY_UNKNOWN;
+	dev->battery_charge_status = POWER_SUPPLY_STATUS_CHARGING;
+	ret = hidinput_get_battery_property(psy, POWER_SUPPLY_PROP_STATUS, &val);
+	KUNIT_EXPECT_EQ(test, ret, 0);
+	KUNIT_EXPECT_EQ(test, val.intval, POWER_SUPPLY_STATUS_UNKNOWN);
+
+	dev->battery_status = HID_BATTERY_REPORTED;
+	dev->battery_charge_status = POWER_SUPPLY_STATUS_CHARGING;
+	ret = hidinput_get_battery_property(psy, POWER_SUPPLY_PROP_STATUS, &val);
+	KUNIT_EXPECT_EQ(test, ret, 0);
+	KUNIT_EXPECT_EQ(test, val.intval, POWER_SUPPLY_STATUS_CHARGING);
+
+	dev->battery_status = HID_BATTERY_REPORTED;
+	dev->battery_charge_status = POWER_SUPPLY_STATUS_DISCHARGING;
+	ret = hidinput_get_battery_property(psy, POWER_SUPPLY_PROP_STATUS, &val);
+	KUNIT_EXPECT_EQ(test, ret, 0);
+	KUNIT_EXPECT_EQ(test, val.intval, POWER_SUPPLY_STATUS_DISCHARGING);
+}
+
+static struct kunit_case hid_input_tests[] = {
+	KUNIT_CASE(hid_test_input_set_battery_charge_status),
+	KUNIT_CASE(hid_test_input_get_battery_property),
+	{ }
+};
+
+static struct kunit_suite hid_input_test_suite = {
+	.name = "hid_input",
+	.test_cases = hid_input_tests,
+};
+
+kunit_test_suite(hid_input_test_suite);
+
+MODULE_DESCRIPTION("HID input KUnit tests");
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("José Expósito <[e-mail]>");

drivers/hid/hid-input.c

···
 		if (dev->battery_status == HID_BATTERY_UNKNOWN)
 			val->intval = POWER_SUPPLY_STATUS_UNKNOWN;
 		else
-			val->intval = POWER_SUPPLY_STATUS_DISCHARGING;
+			val->intval = dev->battery_charge_status;
 		break;
 
 	case POWER_SUPPLY_PROP_SCOPE:
···
 	dev->battery_max = max;
 	dev->battery_report_type = report_type;
 	dev->battery_report_id = field->report->id;
+	dev->battery_charge_status = POWER_SUPPLY_STATUS_DISCHARGING;
 
 	/*
 	 * Stylus is normally not connected to the device and thus we
···
 		power_supply_changed(dev->battery);
 	}
 }
+
+static bool hidinput_set_battery_charge_status(struct hid_device *dev,
+					       unsigned int usage, int value)
+{
+	switch (usage) {
+	case HID_BAT_CHARGING:
+		dev->battery_charge_status = value ?
+					     POWER_SUPPLY_STATUS_CHARGING :
+					     POWER_SUPPLY_STATUS_DISCHARGING;
+		return true;
+	}
+
+	return false;
+}
 #else  /* !CONFIG_HID_BATTERY_STRENGTH */
 static int hidinput_setup_battery(struct hid_device *dev, unsigned report_type,
 				  struct hid_field *field, bool is_percentage)
···
 
 static void hidinput_update_battery(struct hid_device *dev, int value)
 {
+}
+
+static bool hidinput_set_battery_charge_status(struct hid_device *dev,
+					       unsigned int usage, int value)
+{
+	return false;
 }
 #endif	/* CONFIG_HID_BATTERY_STRENGTH */
 
···
 			hidinput_setup_battery(device, HID_INPUT_REPORT, field, true);
 			usage->type = EV_PWR;
 			return;
+		case HID_BAT_CHARGING:
+			usage->type = EV_PWR;
+			return;
 		}
 		goto unknown;
 
···
 		return;
 
 	if (usage->type == EV_PWR) {
-		hidinput_update_battery(hid, value);
+		bool handled = hidinput_set_battery_charge_status(hid, usage->hid, value);
+
+		if (!handled)
+			hidinput_update_battery(hid, value);
+
 		return;
 	}
 
···
 	cancel_work_sync(&hid->led_work);
 }
 EXPORT_SYMBOL_GPL(hidinput_disconnect);
+
+#ifdef CONFIG_HID_KUNIT_TEST
+#include "hid-input-test.c"
+#endif

include/linux/hid.h

···
 #define HID_DG_LATENCYMODE	0x000d0060
 
 #define HID_BAT_ABSOLUTESTATEOFCHARGE	0x00850065
+#define HID_BAT_CHARGING		0x00850044
 
 #define HID_VD_ASUS_CUSTOM_MEDIA_KEYS	0xff310076
 
···
 	__s32 battery_max;
 	__s32 battery_report_type;
 	__s32 battery_report_id;
+	__s32 battery_charge_status;
 	enum hid_battery_status battery_status;
 	bool battery_avoid_query;
 	ktime_t battery_ratelimit_time;