HID: expose wacom pen tablet battery through power_supply class

This patch exposes wacom pen tablet battery capacity and ac state thru
power_supply class is sysfs.

Signed-off-by: Przemo Firszt <przemo@firszt.eu>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

2 files changed, 135 insertions, 0 deletions

diff --git a/drivers/hid/Kconfig b/drivers/hid/Kconfig
index 71d4c0703629..8e1b505b5bf2 100644
--- a/drivers/hid/Kconfig
+++ b/drivers/hid/Kconfig
@@ -357,6 +357,14 @@ config HID_WACOM
         ---help---
         Support for Wacom Graphire Bluetooth tablet.
 
+config HID_WACOM_POWER_SUPPLY
+        bool "Wacom Bluetooth devices power supply status support"
+        depends on HID_WACOM
+        select POWER_SUPPLY
+        ---help---
+          Say Y here if you want to enable power supply status monitoring for
+          Wacom Bluetooth devices.
+
 config HID_ZEROPLUS
         tristate "Zeroplus based game controller support" if EMBEDDED
         depends on USB_HID
diff --git a/drivers/hid/hid-wacom.c b/drivers/hid/hid-wacom.c
index 8d3b46f5d149..4d2d2a2e1a5f 100644
--- a/drivers/hid/hid-wacom.c
+++ b/drivers/hid/hid-wacom.c
@@ -21,14 +21,88 @@
 #include <linux/device.h>
 #include <linux/hid.h>
 #include <linux/module.h>
+#ifdef CONFIG_HID_WACOM_POWER_SUPPLY
+#include <linux/power_supply.h>
+#endif
 
 #include "hid-ids.h"
 
 struct wacom_data {
         __u16 tool;
         unsigned char butstate;
+#ifdef CONFIG_HID_WACOM_POWER_SUPPLY
+        int battery_capacity;
+        struct power_supply battery;
+        struct power_supply ac;
+#endif
 };
 
+#ifdef CONFIG_HID_WACOM_POWER_SUPPLY
+/*percent of battery capacity, 0 means AC online*/
+static unsigned short batcap[8] = { 1, 15, 25, 35, 50, 70, 100, 0 };
+
+static enum power_supply_property wacom_battery_props[] = {
+        POWER_SUPPLY_PROP_PRESENT,
+        POWER_SUPPLY_PROP_CAPACITY
+};
+
+static enum power_supply_property wacom_ac_props[] = {
+        POWER_SUPPLY_PROP_PRESENT,
+        POWER_SUPPLY_PROP_ONLINE
+};
+
+static int wacom_battery_get_property(struct power_supply *psy,
+                                enum power_supply_property psp,
+                                union power_supply_propval *val)
+{
+        struct wacom_data *wdata = container_of(psy,
+                                        struct wacom_data, battery);
+        int power_state = batcap[wdata->battery_capacity];
+        int ret = 0;
+
+        switch (psp) {
+        case POWER_SUPPLY_PROP_PRESENT:
+                val->intval = 1;
+                break;
+        case POWER_SUPPLY_PROP_CAPACITY:
+                /* show 100% battery capacity when charging */
+                if (power_state == 0)
+                        val->intval = 100;
+                else
+                        val->intval = power_state;
+                break;
+        default:
+                ret = -EINVAL;
+                break;
+        }
+        return ret;
+}
+
+static int wacom_ac_get_property(struct power_supply *psy,
+                                enum power_supply_property psp,
+                                union power_supply_propval *val)
+{
+        struct wacom_data *wdata = container_of(psy, struct wacom_data, ac);
+        int power_state = batcap[wdata->battery_capacity];
+        int ret = 0;
+
+        switch (psp) {
+        case POWER_SUPPLY_PROP_PRESENT:
+                /* fall through */
+        case POWER_SUPPLY_PROP_ONLINE:
+                if (power_state == 0)
+                        val->intval = 1;
+                else
+                        val->intval = 0;
+                break;
+        default:
+                ret = -EINVAL;
+                break;
+        }
+        return ret;
+}
+#endif
+
 static int wacom_raw_event(struct hid_device *hdev, struct hid_report *report,
                 u8 *raw_data, int size)
 {
@@ -147,6 +221,12 @@ static int wacom_raw_event(struct hid_device *hdev, struct hid_report *report,
                 input_sync(input);
         }
 
+#ifdef CONFIG_HID_WACOM_POWER_SUPPLY
+        /* Store current battery capacity */
+        rw = (data[7] >> 2 & 0x07);
+        if (rw != wdata->battery_capacity)
+                wdata->battery_capacity = rw;
+#endif
         return 1;
 }
 
@@ -206,6 +286,45 @@ static int wacom_probe(struct hid_device *hdev,
         if (ret < 0)
                 dev_warn(&hdev->dev, "failed to poke device #2, %d\n", ret);
 
+#ifdef CONFIG_HID_WACOM_POWER_SUPPLY
+        wdata->battery.properties = wacom_battery_props;
+        wdata->battery.num_properties = ARRAY_SIZE(wacom_battery_props);
+        wdata->battery.get_property = wacom_battery_get_property;
+        wdata->battery.name = "wacom_battery";
+        wdata->battery.type = POWER_SUPPLY_TYPE_BATTERY;
+        wdata->battery.use_for_apm = 0;
+
+        ret = power_supply_register(&hdev->dev, &wdata->battery);
+        if (ret) {
+                dev_warn(&hdev->dev,
+                        "can't create sysfs battery attribute, err: %d\n", ret);
+                /*
+                 * battery attribute is not critical for the tablet, but if it
+                 * failed then there is no need to create ac attribute
+                 */
+                goto move_on;
+        }
+
+        wdata->ac.properties = wacom_ac_props;
+        wdata->ac.num_properties = ARRAY_SIZE(wacom_ac_props);
+        wdata->ac.get_property = wacom_ac_get_property;
+        wdata->ac.name = "wacom_ac";
+        wdata->ac.type = POWER_SUPPLY_TYPE_MAINS;
+        wdata->ac.use_for_apm = 0;
+
+        ret = power_supply_register(&hdev->dev, &wdata->ac);
+        if (ret) {
+                dev_warn(&hdev->dev,
+                        "can't create ac battery attribute, err: %d\n", ret);
+                /*
+                 * ac attribute is not critical for the tablet, but if it
+                 * failed then we don't want to battery attribute to exist
+                 */
+                power_supply_unregister(&wdata->battery);
+        }
+
+move_on:
+#endif
         hidinput = list_entry(hdev->inputs.next, struct hid_input, list);
         input = hidinput->input;
 
@@ -250,7 +369,15 @@ err_free:
 
 static void wacom_remove(struct hid_device *hdev)
 {
+#ifdef CONFIG_HID_WACOM_POWER_SUPPLY
+        struct wacom_data *wdata = hid_get_drvdata(hdev);
+#endif
         hid_hw_stop(hdev);
+
+#ifdef CONFIG_HID_WACOM_POWER_SUPPLY
+        power_supply_unregister(&wdata->battery);
+        power_supply_unregister(&wdata->ac);
+#endif
         kfree(hid_get_drvdata(hdev));
 }