HID devices that expose a battery strength can have
associated power_supply nodes. This fills in the
SERIAL_NUMBER power_supply field if the same HID device
also has a Digitizer.Transducer Serial Number usage,
effectively allowing that particular stylus to be
identified.
If the field is present and non-zero, the serial number
will be 'DG-ABCD' where 'ABCD' is up to sixteen hex
digits -- field lengths of up to 64-bits are supported,
the largest currently known about.
Devices are expected to emit zero if the transducer
does not have a serial number, or the serial number
has not yet been acquired; zeros will be ignored.
Note that logical min/max (and other HID item
parameters) will be ignored for this field.
Signed-off-by: Kenneth Albanowski <kenalba@xxxxxxxxxx>
---
drivers/hid/hid-input.c | 100 +++++++++++++++++++++++++++++++++++++---
include/linux/hid.h | 5 ++
2 files changed, 99 insertions(+), 6 deletions(-)
diff --git a/drivers/hid/hid-input.c b/drivers/hid/hid-input.c
index ee9e8d31a45ba..c5767ceb4a61c 100644
--- a/drivers/hid/hid-input.c
+++ b/drivers/hid/hid-input.c
@@ -286,6 +286,7 @@ static enum power_supply_property hidinput_battery_props[] = {
POWER_SUPPLY_PROP_ONLINE,
POWER_SUPPLY_PROP_CAPACITY,
POWER_SUPPLY_PROP_MODEL_NAME,
+ POWER_SUPPLY_PROP_SERIAL_NUMBER,
POWER_SUPPLY_PROP_STATUS,
POWER_SUPPLY_PROP_SCOPE,
};
@@ -402,6 +403,26 @@ static int hidinput_get_battery_property(struct power_supply *psy,
val->strval = dev->name;
break;
+ case POWER_SUPPLY_PROP_SERIAL_NUMBER:
+ /* Serial number does not have an active HID query
+ * mechanism like hidinput_query_battery_capacity, as the
+ * only devices expected to have serial numbers are digitizers,
+ * which are unlikely to be able to pull the serial number from
+ * an untethered pen on demand.
+ */
+ if (dev->battery_serial_number == 0) {
+ /* Make no claims about S/N format if we haven't actually seen a value yet. */
+ strcpy(dev->battery_serial_number_str, "");
+ } else {
+ snprintf(dev->battery_serial_number_str,
+ sizeof(dev->battery_serial_number_str),
+ "DG-%0*llX",
+ DIV_ROUND_UP(dev->battery_serial_number_bits, 4),
+ dev->battery_serial_number);
+ }
+ val->strval = dev->battery_serial_number_str;
+ break;
+
case POWER_SUPPLY_PROP_STATUS:
if (dev->battery_status != HID_BATTERY_REPORTED &&
!dev->battery_avoid_query) {
@@ -485,6 +506,8 @@ static int hidinput_setup_battery(struct hid_device *dev, unsigned report_type,
dev->battery_max = max;
dev->battery_report_type = report_type;
dev->battery_report_id = field->report->id;
+ dev->battery_changed = false;
+ dev->battery_reported = false;
/*
* Stylus is normally not connected to the device and thus we
@@ -526,7 +549,8 @@ static void hidinput_cleanup_battery(struct hid_device *dev)
dev->battery = NULL;
}
-static void hidinput_update_battery(struct hid_device *dev, int value)
+static void hidinput_update_battery_capacity(struct hid_device *dev,
+ __s32 value)
{
int capacity;
@@ -538,11 +562,57 @@ static void hidinput_update_battery(struct hid_device *dev, int value)
capacity = hidinput_scale_battery_capacity(dev, value);
+ if (capacity != dev->battery_capacity) {
+ dev->battery_capacity = capacity;
+ dev->battery_changed = true;
+ }
+ dev->battery_reported = true;
+}
+
+static void hidinput_update_battery_serial(struct hid_device *dev,
+ const __s32 *values, int bits)
+{
+ __u64 value;
+
+ if (!dev->battery)
+ return;
+
+ if (bits > 64)
+ bits = 64;
+
+ value = (__u64)(__u32)values[0];
+ if (bits > 32)
+ value |= (__u64)values[1] << 32;
+
+ if (value == 0)
+ return;
+
+ if (value != dev->battery_serial_number) {
+ dev->battery_serial_number = value;
+ dev->battery_serial_number_bits = bits;
+ dev->battery_changed = true;
+ }
+ dev->battery_reported = true;
+}
+
+static void hidinput_flush_battery(struct hid_device *dev)
+{
+ if (!dev->battery)
+ return;
+
+ /* Only consider pushing a battery change if there is a
+ * battery field in this report.
+ */
+ if (!dev->battery_reported)
+ return;
+
+ dev->battery_reported = false;
+
if (dev->battery_status != HID_BATTERY_REPORTED ||
- capacity != dev->battery_capacity ||
+ dev->battery_changed ||
ktime_after(ktime_get_coarse(), dev->battery_ratelimit_time)) {
- dev->battery_capacity = capacity;
dev->battery_status = HID_BATTERY_REPORTED;
+ dev->battery_changed = false;
dev->battery_ratelimit_time =
ktime_add_ms(ktime_get_coarse(), 30 * 1000);
power_supply_changed(dev->battery);
@@ -559,7 +629,17 @@ static void hidinput_cleanup_battery(struct hid_device *dev)
{
}
-static void hidinput_update_battery(struct hid_device *dev, int value)
+static void hidinput_update_battery_capacity(struct hid_device *dev,
+ __s32 value)
+{
+}
+
+static void hidinput_update_battery_serial(struct hid_device *dev,
+ const __s32 *values, int bits)
+{
+}
+
+static void hidinput_flush_battery(struct hid_device *dev)
{
}
#endif /* CONFIG_HID_BATTERY_STRENGTH */
@@ -1273,7 +1353,9 @@ static void hidinput_handle_scroll(struct hid_usage *usage,
input_event(input, EV_REL, usage->code, hi_res);
}
-void hidinput_hid_event(struct hid_device *hid, struct hid_field *field, struct hid_usage *usage, const __s32 *values, unsigned value_count)
+void hidinput_hid_event(struct hid_device *hid, struct hid_field *field,
+ struct hid_usage *usage, const __s32 *values,
+ unsigned value_count)
{
struct input_dev *input;
unsigned *quirks = &hid->quirks;
@@ -1290,9 +1372,13 @@ void hidinput_hid_event(struct hid_device *hid, struct hid_field *field, struct
return;
if (usage->type == EV_PWR) {
- hidinput_update_battery(hid, value);
+ hidinput_update_battery_capacity(hid, value);
return;
}
+ if (usage->type == EV_MSC && usage->code == MSC_SERIAL) {
+ hidinput_update_battery_serial(hid, values, field->report_size);
+ /* fall through to normal standard MSC_SERIAL processing */
+ }
if (!field->hidinput)
return;
@@ -1423,6 +1509,8 @@ void hidinput_report_event(struct hid_device *hid, struct hid_report *report)
{
struct hid_input *hidinput;
+ hidinput_flush_battery(hid);
+
if (hid->quirks & HID_QUIRK_NO_INPUT_SYNC)
return;
diff --git a/include/linux/hid.h b/include/linux/hid.h
index 8494b1995b10b..d5585a99b5ad9 100644
--- a/include/linux/hid.h
+++ b/include/linux/hid.h
@@ -587,8 +587,13 @@ struct hid_device { /* device report descriptor */
__s32 battery_max;
__s32 battery_report_type;
__s32 battery_report_id;
+ __u64 battery_serial_number;
+ int battery_serial_number_bits; /* Actual number of bits in SN */
+ char battery_serial_number_str[20]; /* Space for "DG-" + max 16 hex digits */
enum hid_battery_status battery_status;
bool battery_avoid_query;
+ bool battery_changed;
+ bool battery_reported;
ktime_t battery_ratelimit_time;
#endif
--
2.31.0
