Re: [PATCH 3/3] HID: steam: add battery device.

The wireless Steam Controller is battery operated, so add the battery
device and power information.

Signed-off-by: Rodrigo Rivas Costa <redacted>
---
 drivers/hid/hid-steam.c | 139 +++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 138 insertions(+), 1 deletion(-)

diff --git a/drivers/hid/hid-steam.c b/drivers/hid/hid-steam.c
index f269a986e2be..eb2424688092 100644
--- a/drivers/hid/hid-steam.c
+++ b/drivers/hid/hid-steam.c

@@ -20,6 +20,7 @@
 #include <linux/hid.h>
 #include <linux/module.h>
 #include <linux/workqueue.h>
+#include <linux/power_supply.h>
 #include "hid-ids.h"

 MODULE_LICENSE("GPL");

@@ -35,6 +36,10 @@ struct steam_device {
        struct work_struct work_connect;
        bool connected;
        char serial_no[11];
+       struct power_supply_desc battery_desc;
+       struct power_supply *battery;
+       u8 battery_charge;
+       u16 voltage;
 };

 static int steam_register(struct steam_device *steam);

@@ -45,6 +50,8 @@ static int steam_send_report(struct steam_device *steam,
                u8 *cmd, int size);
 static int steam_recv_report(struct steam_device *steam,
                u8 *data, int size);
+static int steam_battery_register(struct steam_device *steam);
+static void steam_do_battery_event(struct steam_device *steam, u8 *data);

 static int steam_input_open(struct input_dev *dev)
 {

@@ -311,7 +318,8 @@ static int steam_raw_event(struct hid_device *hdev,
                }
                break;
        case 0x04:
-               /* TODO battery status */
+               if (steam->quirks & STEAM_QUIRK_WIRELESS)
+                       steam_do_battery_event(steam, data);
                break;
        }
        return 0;

@@ -517,6 +525,10 @@ static int steam_register(struct steam_device *steam)

        steam->input_dev = input;

+       /* ignore battery errors, we can live without it */
+       if (steam->quirks & STEAM_QUIRK_WIRELESS)
+               steam_battery_register(steam);
+
        return 0;

 input_register_fail:

@@ -528,6 +540,12 @@ static void steam_unregister(struct steam_device *steam)
 {
        dbg_hid("%s\n", __func__);

+       if (steam->battery) {
+               power_supply_unregister(steam->battery);
+               steam->battery = NULL;
+               kfree(steam->battery_desc.name);
+               steam->battery_desc.name = NULL;
+       }
        if (steam->input_dev) {
                hid_info(steam->hid_dev, "Steam Controller SN: '%s' disconnected",
                        steam->serial_no);

@@ -536,6 +554,125 @@ static void steam_unregister(struct steam_device *steam)
        }
 }

+/* The size for this message payload is 11.
+ * The known values are:
+ *  Offset| Type  | Meaning
+ * -------+-------+---------------------------
+ *  4-7   | u32   | sequence number
+ *  8-11  | --    | always 0
+ *  12-13 | u16   | voltage (mV)
+ *  14    | u8    | battery percent
+ */
+static void steam_do_battery_event(struct steam_device *steam, u8 *data)
+{
+       unsigned long flags;
+       s16 volts = le16_to_cpup((__le16 *)(data + 12));
+       u8 batt = data[14];
+
+       dbg_hid("%s: %d %d\n", __func__, volts, batt);
+
+       if (unlikely(!steam->battery)) {
+               dbg_hid("%s: battery data without connect event\n", __func__);
+               steam_do_connect_event(steam, true);
+               return;
+       }
+
+       spin_lock_irqsave(&steam->lock, flags);
+       steam->voltage = volts;
+       steam->battery_charge = batt;
+       spin_unlock_irqrestore(&steam->lock, flags);
+
+       power_supply_changed(steam->battery);
+}
+
+static enum power_supply_property steam_battery_props[] = {
+       POWER_SUPPLY_PROP_PRESENT,
+       POWER_SUPPLY_PROP_SCOPE,
+       POWER_SUPPLY_PROP_VOLTAGE_NOW,
+       POWER_SUPPLY_PROP_CAPACITY,
+};
+
+static int steam_battery_get_property(struct power_supply *psy,
+                                    enum power_supply_property psp,
+                                    union power_supply_propval *val)
+{
+       struct steam_device *steam = power_supply_get_drvdata(psy);
+       unsigned long flags;
+       s16 volts;
+       u8 batt;
+       int ret = 0;
+
+       spin_lock_irqsave(&steam->lock, flags);
+       volts = steam->voltage;
+       batt = steam->battery_charge;
+       spin_unlock_irqrestore(&steam->lock, flags);
+
+       switch (psp) {
+       case POWER_SUPPLY_PROP_PRESENT:
+               val->intval = 1;
+               break;
+       case POWER_SUPPLY_PROP_SCOPE:
+               val->intval = POWER_SUPPLY_SCOPE_DEVICE;
+               break;
+       case POWER_SUPPLY_PROP_VOLTAGE_NOW:
+               val->intval = volts * 1000; /* mV -> uV */
+               break;
+       case POWER_SUPPLY_PROP_CAPACITY:
+               val->intval = batt;
+               break;
+       default:
+               ret = -EINVAL;
+               break;
+       }
+       return ret;
+}
+
+static int steam_battery_register(struct steam_device *steam)
+{
+       struct power_supply *battery;
+       struct power_supply_config battery_cfg = { .drv_data = steam, };
+       unsigned long flags;
+       int ret;
+
+       dbg_hid("%s\n", __func__);
+
+       steam->battery_desc.type = POWER_SUPPLY_TYPE_BATTERY;
+       steam->battery_desc.properties = steam_battery_props;
+       steam->battery_desc.num_properties = ARRAY_SIZE(steam_battery_props);
+       steam->battery_desc.get_property = steam_battery_get_property;
+       steam->battery_desc.name = kasprintf(GFP_KERNEL,
+                       "steam-controller-%s-battery", steam->serial_no);