linux-kernel - [PATCH V2 1/1] HID: i2c-hid: Add API to wait for device reset completion

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Message-ID: <20251117023959.594514-2-Qing-wu.Li@leica-geosystems.com.cn>
Date: Mon, 17 Nov 2025 02:39:59 +0000
From: LI Qingwu <Qing-wu.Li@...ca-geosystems.com.cn>
To: jikos@...nel.org,
	bentiss@...nel.org,
	dianders@...omium.org,
	treapking@...omium.org,
	alex.vinarskis@...il.com,
	dan.carpenter@...aro.org,
	superm1@...nel.org,
	guanwentao@...ontech.com,
	kl@...wtf,
	Qing-wu.Li@...ca-geosystems.com.cn,
	linux-input@...r.kernel.org,
	linux-kernel@...r.kernel.org
Cc: liqind@....com
Subject: [PATCH V2 1/1] HID: i2c-hid: Add API to wait for device reset completion

Some HID over I2C devices need to signal reset completion to the host
after firmware updates or device resets. Per the HID over I2C spec,
devices signal completion by sending an empty input report (0x0000).

Add i2c_hid_wait_reset_complete() to allow drivers to synchronize
with device reset operations. The function sets I2C_HID_RESET_PENDING
and waits for the device's completion signal.

Returns: 0 on success, -ETIMEDOUT on timeout.

Signed-off-by: LI Qingwu <Qing-wu.Li@...ca-geosystems.com.cn>
---
 drivers/hid/i2c-hid/i2c-hid-core.c | 28 ++++++++++++++++++++++++++++
 drivers/hid/i2c-hid/i2c-hid.h      |  1 +
 2 files changed, 29 insertions(+)

diff --git a/drivers/hid/i2c-hid/i2c-hid-core.c b/drivers/hid/i2c-hid/i2c-hid-core.c
index 63f46a2e5788..906249c94395 100644
--- a/drivers/hid/i2c-hid/i2c-hid-core.c
+++ b/drivers/hid/i2c-hid/i2c-hid-core.c
@@ -1401,6 +1401,34 @@ const struct dev_pm_ops i2c_hid_core_pm = {
 };
 EXPORT_SYMBOL_GPL(i2c_hid_core_pm);
 
+int i2c_hid_wait_reset_complete(struct device *dev, unsigned long timeout_ms)
+{
+	struct i2c_client *client;
+	struct i2c_hid *ihid;
+
+	if (!dev)
+		return -ENODEV;
+
+	client = to_i2c_client(dev);
+	if (client == NULL)
+		return -ENODEV;
+
+	ihid = i2c_get_clientdata(client);
+	if (!ihid)
+		return -ENODEV;
+
+	set_bit(I2C_HID_RESET_PENDING, &ihid->flags);
+	if (wait_event_timeout(ihid->wait,
+			       !test_bit(I2C_HID_RESET_PENDING, &ihid->flags),
+			       msecs_to_jiffies(timeout_ms)))
+		return 0;
+	else
+		clear_bit(I2C_HID_RESET_PENDING, &ihid->flags);
+
+	return -ETIMEDOUT;
+}
+EXPORT_SYMBOL_GPL(i2c_hid_wait_reset_complete);
+
 MODULE_DESCRIPTION("HID over I2C core driver");
 MODULE_AUTHOR("Benjamin Tissoires <benjamin.tissoires@...il.com>");
 MODULE_LICENSE("GPL");
diff --git a/drivers/hid/i2c-hid/i2c-hid.h b/drivers/hid/i2c-hid/i2c-hid.h
index 1724a435c783..8e5482baa679 100644
--- a/drivers/hid/i2c-hid/i2c-hid.h
+++ b/drivers/hid/i2c-hid/i2c-hid.h
@@ -42,6 +42,7 @@ void i2c_hid_core_remove(struct i2c_client *client);
 
 void i2c_hid_core_shutdown(struct i2c_client *client);
 
+int i2c_hid_wait_reset_complete(struct device *dev, unsigned long timeout_ms);
 extern const struct dev_pm_ops i2c_hid_core_pm;
 
 #endif
-- 
2.43.0