diff mbox series

[v2,02/12] HID: hexLIN: Add support for USB LIN bus adapter

Message ID 20240502075534.882628-3-christoph.fritz@hexdev.de (mailing list archive)
State Superseded
Delegated to: Jiri Kosina
Headers show
Series LIN Bus support for Linux | expand

Commit Message

Christoph Fritz May 2, 2024, 7:55 a.m. UTC
This patch introduces driver support for the hexLIN USB LIN bus adapter,
enabling LIN communication over USB for both controller and responder
modes. The driver interfaces with the CAN_LIN framework for userland
connectivity.

For more details on the adapter, visit: https://hexdev.de/hexlin/

Tested-by: Andreas Lauser <andreas.lauser@mercedes-benz.com>
Signed-off-by: Christoph Fritz <christoph.fritz@hexdev.de>
---
 drivers/hid/Kconfig             |  19 +
 drivers/hid/Makefile            |   1 +
 drivers/hid/hid-hexdev-hexlin.c | 630 ++++++++++++++++++++++++++++++++
 drivers/hid/hid-ids.h           |   1 +
 drivers/hid/hid-quirks.c        |   3 +
 5 files changed, 654 insertions(+)
 create mode 100644 drivers/hid/hid-hexdev-hexlin.c

Comments

Jiri Slaby May 2, 2024, 8:30 a.m. UTC | #1
On 02. 05. 24, 9:55, Christoph Fritz wrote:
> This patch introduces driver support for the hexLIN USB LIN bus adapter,
> enabling LIN communication over USB for both controller and responder
> modes. The driver interfaces with the CAN_LIN framework for userland
> connectivity.
> 
> For more details on the adapter, visit: https://hexdev.de/hexlin/
> 
> Tested-by: Andreas Lauser <andreas.lauser@mercedes-benz.com>
> Signed-off-by: Christoph Fritz <christoph.fritz@hexdev.de>
...
> --- /dev/null
> +++ b/drivers/hid/hid-hexdev-hexlin.c
> @@ -0,0 +1,630 @@
...
> +static int hexlin_stop(struct lin_device *ldev)
> +{
> +	struct hid_device *hdev = to_hid_device(ldev->dev);
> +	struct hexlin_priv_data *priv = hid_get_drvdata(hdev);
> +
> +	hid_hw_close(hdev);
> +
> +	priv->is_error = true;
> +	complete(&priv->wait_in_report);
> +
> +	mutex_lock(&priv->tx_lock);
> +	mutex_unlock(&priv->tx_lock);

This is a weird way to implement a completion. It looks like you need 
another one.

> +	return 0;
> +}
...> +static int hexlin_probe(struct hid_device *hdev,
> +			const struct hid_device_id *id)
> +{
> +	struct hexlin_priv_data *priv;
> +	int ret;
> +
> +	priv = devm_kzalloc(&hdev->dev, sizeof(*priv), GFP_KERNEL);
> +	if (!priv)
> +		return -ENOMEM;
> +
> +	priv->hid_dev = hdev;
> +	hid_set_drvdata(hdev, priv);
> +
> +	mutex_init(&priv->tx_lock);
> +
> +	ret = hid_parse(hdev);
> +	if (ret) {
> +		hid_err(hdev, "hid parse failed with %d\n", ret);
> +		goto fail_and_free;
> +	}
> +
> +	ret = hid_hw_start(hdev, HID_CONNECT_DRIVER);
> +	if (ret) {
> +		hid_err(hdev, "hid hw start failed with %d\n", ret);
> +		goto fail_and_stop;
> +	}
> +
> +	ret = hid_hw_open(hdev);
> +	if (ret) {
> +		hid_err(hdev, "hid hw open failed with %d\n", ret);
> +		goto fail_and_close;
> +	}
> +
> +	init_completion(&priv->wait_in_report);
> +
> +	hid_device_io_start(hdev);
> +
> +	ret = init_hw(priv);
> +	if (ret)
> +		goto fail_and_close;
> +
> +	priv->ldev = register_lin(&hdev->dev, &hexlin_ldo);
> +	if (IS_ERR_OR_NULL(priv->ldev)) {
> +		ret = PTR_ERR(priv->ldev);
> +		goto fail_and_close;
> +	}
> +
> +	hid_hw_close(hdev);
> +
> +	hid_info(hdev, "hexLIN (fw-version: %u) probed\n", priv->fw_version);
> +
> +	return 0;
> +
> +fail_and_close:
> +	hid_hw_close(hdev);
> +fail_and_stop:
> +	hid_hw_stop(hdev);
> +fail_and_free:
> +	mutex_destroy(&priv->tx_lock);
> +	return ret;
> +}
> +
> +static void hexlin_remove(struct hid_device *hdev)
> +{
> +	struct hexlin_priv_data *priv = hid_get_drvdata(hdev);
> +
> +	unregister_lin(priv->ldev);
> +	hid_hw_stop(hdev);
> +	mutex_destroy(&priv->tx_lock);

It is unusual to destroy a mutex. Why do you do that?

> +}
...
> +static int __init hexlin_init(void)
> +{
> +	return hid_register_driver(&hexlin_driver);
> +}
> +
> +static void __exit hexlin_exit(void)
> +{
> +	hid_unregister_driver(&hexlin_driver);
> +}



> +
> +/*
> + * When compiled into the kernel, initialize after the hid bus.
> + */
> +late_initcall(hexlin_init);

Hmm, why not module_init() then? (And module_hid_driver().)

> +module_exit(hexlin_exit);
> +
> +MODULE_LICENSE("GPL");
> +MODULE_AUTHOR("Christoph Fritz <christoph.fritz@hexdev.de>");
> +MODULE_DESCRIPTION("LIN bus driver for hexLIN USB adapter");

thanks,
Christoph Fritz May 2, 2024, 10:41 a.m. UTC | #2
On Thu, 2024-05-02 at 10:30 +0200, Jiri Slaby wrote:
> On 02. 05. 24, 9:55, Christoph Fritz wrote:
> > This patch introduces driver support for the hexLIN USB LIN bus adapter,
> > enabling LIN communication over USB for both controller and responder
> > modes. The driver interfaces with the CAN_LIN framework for userland
> > connectivity.
> > 
> > For more details on the adapter, visit: https://hexdev.de/hexlin/
> > 
> > Tested-by: Andreas Lauser <andreas.lauser@mercedes-benz.com>
> > Signed-off-by: Christoph Fritz <christoph.fritz@hexdev.de>
> ...
> > --- /dev/null
> > +++ b/drivers/hid/hid-hexdev-hexlin.c
> > @@ -0,0 +1,630 @@
> ...
> > +static int hexlin_stop(struct lin_device *ldev)
> > +{
> > +	struct hid_device *hdev = to_hid_device(ldev->dev);
> > +	struct hexlin_priv_data *priv = hid_get_drvdata(hdev);
> > +
> > +	hid_hw_close(hdev);
> > +
> > +	priv->is_error = true;
> > +	complete(&priv->wait_in_report);
> > +
> > +	mutex_lock(&priv->tx_lock);
> > +	mutex_unlock(&priv->tx_lock);
> 
> This is a weird way to implement a completion. It looks like you need 
> another one.

They are not necessary, even more so when I can drop the
mutex_destroy() below.

> 
> > +	return 0;
> > +}
> ...> +static int hexlin_probe(struct hid_device *hdev,
> > +			const struct hid_device_id *id)
> > +{
> > +	struct hexlin_priv_data *priv;
> > +	int ret;
> > +
> > +	priv = devm_kzalloc(&hdev->dev, sizeof(*priv), GFP_KERNEL);
> > +	if (!priv)
> > +		return -ENOMEM;
> > +
> > +	priv->hid_dev = hdev;
> > +	hid_set_drvdata(hdev, priv);
> > +
> > +	mutex_init(&priv->tx_lock);
> > +
> > +	ret = hid_parse(hdev);
> > +	if (ret) {
> > +		hid_err(hdev, "hid parse failed with %d\n", ret);
> > +		goto fail_and_free;
> > +	}
> > +
> > +	ret = hid_hw_start(hdev, HID_CONNECT_DRIVER);
> > +	if (ret) {
> > +		hid_err(hdev, "hid hw start failed with %d\n", ret);
> > +		goto fail_and_stop;
> > +	}
> > +
> > +	ret = hid_hw_open(hdev);
> > +	if (ret) {
> > +		hid_err(hdev, "hid hw open failed with %d\n", ret);
> > +		goto fail_and_close;
> > +	}
> > +
> > +	init_completion(&priv->wait_in_report);
> > +
> > +	hid_device_io_start(hdev);
> > +
> > +	ret = init_hw(priv);
> > +	if (ret)
> > +		goto fail_and_close;
> > +
> > +	priv->ldev = register_lin(&hdev->dev, &hexlin_ldo);
> > +	if (IS_ERR_OR_NULL(priv->ldev)) {
> > +		ret = PTR_ERR(priv->ldev);
> > +		goto fail_and_close;
> > +	}
> > +
> > +	hid_hw_close(hdev);
> > +
> > +	hid_info(hdev, "hexLIN (fw-version: %u) probed\n", priv->fw_version);
> > +
> > +	return 0;
> > +
> > +fail_and_close:
> > +	hid_hw_close(hdev);
> > +fail_and_stop:
> > +	hid_hw_stop(hdev);
> > +fail_and_free:
> > +	mutex_destroy(&priv->tx_lock);
> > +	return ret;
> > +}
> > +
> > +static void hexlin_remove(struct hid_device *hdev)
> > +{
> > +	struct hexlin_priv_data *priv = hid_get_drvdata(hdev);
> > +
> > +	unregister_lin(priv->ldev);
> > +	hid_hw_stop(hdev);
> > +	mutex_destroy(&priv->tx_lock);
> 
> It is unusual to destroy a mutex. Why do you do that?
> 

Just for code clarity and it should help if someone wants to use
CONFIG_DEBUG_MUTEXES.

To be able to drop the lock/unlock from above, I could add the
lock/unlock here or just drop the mutex_destroy() completely.

I'll just drop it in upcoming v3.

> > +}
> ...
> > +static int __init hexlin_init(void)
> > +{
> > +	return hid_register_driver(&hexlin_driver);
> > +}
> > +
> > +static void __exit hexlin_exit(void)
> > +{
> > +	hid_unregister_driver(&hexlin_driver);
> > +}
> 
> 
> 
> > +
> > +/*
> > + * When compiled into the kernel, initialize after the hid bus.
> > + */
> > +late_initcall(hexlin_init);
> 
> Hmm, why not module_init() then? (And module_hid_driver().)

Looking at the other hid drivers and testing with just

module_hid_driver(hexlin_driver)

works here fine for compiled into the kernel and as a module.

> 
> > +module_exit(hexlin_exit);
> > +
> > +MODULE_LICENSE("GPL");
> > +MODULE_AUTHOR("Christoph Fritz <christoph.fritz@hexdev.de>");
> > +MODULE_DESCRIPTION("LIN bus driver for hexLIN USB adapter");

Thanks
  -- Christoph
Simon Horman May 4, 2024, 12:58 p.m. UTC | #3
On Thu, May 02, 2024 at 09:55:24AM +0200, Christoph Fritz wrote:
> This patch introduces driver support for the hexLIN USB LIN bus adapter,
> enabling LIN communication over USB for both controller and responder
> modes. The driver interfaces with the CAN_LIN framework for userland
> connectivity.
> 
> For more details on the adapter, visit: https://hexdev.de/hexlin/
> 
> Tested-by: Andreas Lauser <andreas.lauser@mercedes-benz.com>
> Signed-off-by: Christoph Fritz <christoph.fritz@hexdev.de>

Hi Christoph,

Some minor feedback from my side.

...

> diff --git a/drivers/hid/hid-hexdev-hexlin.c b/drivers/hid/hid-hexdev-hexlin.c

...

> +static int hexlin_queue_frames_insert(struct hexlin_priv_data *priv,
> +				      const u8 *raw_data, int sz)
> +{
> +	struct hid_device *hdev = priv->hid_dev;
> +	struct hexlin_frame hxf;
> +	struct lin_frame lf;
> +
> +	if (sz != sizeof(struct hexlin_frame))
> +		return -EREMOTEIO;
> +
> +	memcpy(&hxf, raw_data, sz);
> +	le32_to_cpus(hxf.flags);
> +
> +	lf.len = hxf.len;
> +	lf.lin_id = hxf.lin_id;
> +	memcpy(lf.data, hxf.data, LIN_MAX_DLEN);
> +	lf.checksum = hxf.checksum;
> +	lf.checksum_mode = hxf.checksum_mode;
> +
> +	hid_dbg(hdev, "id:%02x, len:%u, data:%*ph, checksum:%02x (%s)\n",
> +		   lf.lin_id, lf.len, lf.len, lf.data, lf.checksum,
> +		   lf.checksum_mode ? "enhanced" : "classic");

nit: The indentation above is not quite right.
     It should align to inside the opening '(' like this.

	hid_dbg(hdev, "id:%02x, len:%u, data:%*ph, checksum:%02x (%s)\n",
		lf.lin_id, lf.len, lf.len, lf.data, lf.checksum,
		lf.checksum_mode ? "enhanced" : "classic");

Flagged by checkpatch.

...

> +static int hexlin_set_baudrate(struct hexlin_priv_data *priv, u16 baudrate)
> +{
> +	struct hexlin_baudrate_req req;
> +	int ret;
> +
> +	if (baudrate < LIN_MIN_BAUDRATE || baudrate > LIN_MAX_BAUDRATE)
> +		return -EINVAL;
> +
> +	req.cmd = HEXLIN_SET_BAUDRATE;
> +	req.baudrate = cpu_to_le16(baudrate);

The type of req.baudrate is u16, a host byte-order type.
But it is being assigned a little endian value.
This does not seem right.

Flagged by Smatch.

> +
> +	ret = hexlin_tx_req_status(priv, &req,
> +				   sizeof(struct hexlin_baudrate_req));
> +	if (ret)
> +		hid_err(priv->hid_dev, "%s failed with %d\n", __func__, ret);
> +
> +	return ret;
> +}

...

> +static int hexlin_probe(struct hid_device *hdev,
> +			const struct hid_device_id *id)
> +{
> +	struct hexlin_priv_data *priv;
> +	int ret;
> +
> +	priv = devm_kzalloc(&hdev->dev, sizeof(*priv), GFP_KERNEL);
> +	if (!priv)
> +		return -ENOMEM;
> +
> +	priv->hid_dev = hdev;
> +	hid_set_drvdata(hdev, priv);
> +
> +	mutex_init(&priv->tx_lock);
> +
> +	ret = hid_parse(hdev);
> +	if (ret) {
> +		hid_err(hdev, "hid parse failed with %d\n", ret);
> +		goto fail_and_free;
> +	}
> +
> +	ret = hid_hw_start(hdev, HID_CONNECT_DRIVER);
> +	if (ret) {
> +		hid_err(hdev, "hid hw start failed with %d\n", ret);
> +		goto fail_and_stop;
> +	}
> +
> +	ret = hid_hw_open(hdev);
> +	if (ret) {
> +		hid_err(hdev, "hid hw open failed with %d\n", ret);
> +		goto fail_and_close;
> +	}
> +
> +	init_completion(&priv->wait_in_report);
> +
> +	hid_device_io_start(hdev);
> +
> +	ret = init_hw(priv);
> +	if (ret)
> +		goto fail_and_close;
> +
> +	priv->ldev = register_lin(&hdev->dev, &hexlin_ldo);
> +	if (IS_ERR_OR_NULL(priv->ldev)) {
> +		ret = PTR_ERR(priv->ldev);
> +		goto fail_and_close;

Is it intentional that when priv->ldev is NULL here,
the function will return 0?

Flagged by Smatch.

> +	}
> +
> +	hid_hw_close(hdev);
> +
> +	hid_info(hdev, "hexLIN (fw-version: %u) probed\n", priv->fw_version);
> +
> +	return 0;
> +
> +fail_and_close:
> +	hid_hw_close(hdev);
> +fail_and_stop:
> +	hid_hw_stop(hdev);
> +fail_and_free:
> +	mutex_destroy(&priv->tx_lock);
> +	return ret;
> +}

...
Christoph Fritz May 8, 2024, 8:37 a.m. UTC | #4
On Sat, 2024-05-04 at 13:58 +0100, Simon Horman wrote:
> On Thu, May 02, 2024 at 09:55:24AM +0200, Christoph Fritz wrote:
> > This patch introduces driver support for the hexLIN USB LIN bus adapter,
> > enabling LIN communication over USB for both controller and responder
> > modes. The driver interfaces with the CAN_LIN framework for userland
> > connectivity.
> > 
> > For more details on the adapter, visit: https://hexdev.de/hexlin/
> > 
> > Tested-by: Andreas Lauser <andreas.lauser@mercedes-benz.com>
> > Signed-off-by: Christoph Fritz <christoph.fritz@hexdev.de>
> 
> Hi Christoph,
> 
> Some minor feedback from my side.
> 
> ...
> 
> > diff --git a/drivers/hid/hid-hexdev-hexlin.c b/drivers/hid/hid-hexdev-hexlin.c
> 
> ...
> 
> > +static int hexlin_queue_frames_insert(struct hexlin_priv_data *priv,
> > +				      const u8 *raw_data, int sz)
> > +{
> > +	struct hid_device *hdev = priv->hid_dev;
> > +	struct hexlin_frame hxf;
> > +	struct lin_frame lf;
> > +
> > +	if (sz != sizeof(struct hexlin_frame))
> > +		return -EREMOTEIO;
> > +
> > +	memcpy(&hxf, raw_data, sz);
> > +	le32_to_cpus(hxf.flags);
> > +
> > +	lf.len = hxf.len;
> > +	lf.lin_id = hxf.lin_id;
> > +	memcpy(lf.data, hxf.data, LIN_MAX_DLEN);
> > +	lf.checksum = hxf.checksum;
> > +	lf.checksum_mode = hxf.checksum_mode;
> > +
> > +	hid_dbg(hdev, "id:%02x, len:%u, data:%*ph, checksum:%02x (%s)\n",
> > +		   lf.lin_id, lf.len, lf.len, lf.data, lf.checksum,
> > +		   lf.checksum_mode ? "enhanced" : "classic");
> 
> nit: The indentation above is not quite right.
>      It should align to inside the opening '(' like this.
> 
> 	hid_dbg(hdev, "id:%02x, len:%u, data:%*ph, checksum:%02x (%s)\n",
> 		lf.lin_id, lf.len, lf.len, lf.data, lf.checksum,
> 		lf.checksum_mode ? "enhanced" : "classic");
> 
> Flagged by checkpatch.

OK

> 
> ...
> 
> > +static int hexlin_set_baudrate(struct hexlin_priv_data *priv, u16 baudrate)
> > +{
> > +	struct hexlin_baudrate_req req;
> > +	int ret;
> > +
> > +	if (baudrate < LIN_MIN_BAUDRATE || baudrate > LIN_MAX_BAUDRATE)
> > +		return -EINVAL;
> > +
> > +	req.cmd = HEXLIN_SET_BAUDRATE;
> > +	req.baudrate = cpu_to_le16(baudrate);
> 
> The type of req.baudrate is u16, a host byte-order type.
> But it is being assigned a little endian value.
> This does not seem right.
> 
> Flagged by Smatch.

In upcoming v4 I'll use __le16

> 
> > +
> > +	ret = hexlin_tx_req_status(priv, &req,
> > +				   sizeof(struct hexlin_baudrate_req));
> > +	if (ret)
> > +		hid_err(priv->hid_dev, "%s failed with %d\n", __func__, ret);
> > +
> > +	return ret;
> > +}
> 
> ...
> 
> > +static int hexlin_probe(struct hid_device *hdev,
> > +			const struct hid_device_id *id)
> > +{
> > +	struct hexlin_priv_data *priv;
> > +	int ret;
> > +
> > +	priv = devm_kzalloc(&hdev->dev, sizeof(*priv), GFP_KERNEL);
> > +	if (!priv)
> > +		return -ENOMEM;
> > +
> > +	priv->hid_dev = hdev;
> > +	hid_set_drvdata(hdev, priv);
> > +
> > +	mutex_init(&priv->tx_lock);
> > +
> > +	ret = hid_parse(hdev);
> > +	if (ret) {
> > +		hid_err(hdev, "hid parse failed with %d\n", ret);
> > +		goto fail_and_free;
> > +	}
> > +
> > +	ret = hid_hw_start(hdev, HID_CONNECT_DRIVER);
> > +	if (ret) {
> > +		hid_err(hdev, "hid hw start failed with %d\n", ret);
> > +		goto fail_and_stop;
> > +	}
> > +
> > +	ret = hid_hw_open(hdev);
> > +	if (ret) {
> > +		hid_err(hdev, "hid hw open failed with %d\n", ret);
> > +		goto fail_and_close;
> > +	}
> > +
> > +	init_completion(&priv->wait_in_report);
> > +
> > +	hid_device_io_start(hdev);
> > +
> > +	ret = init_hw(priv);
> > +	if (ret)
> > +		goto fail_and_close;
> > +
> > +	priv->ldev = register_lin(&hdev->dev, &hexlin_ldo);
> > +	if (IS_ERR_OR_NULL(priv->ldev)) {
> > +		ret = PTR_ERR(priv->ldev);
> > +		goto fail_and_close;
> 
> Is it intentional that when priv->ldev is NULL here,
> the function will return 0?
> 
> Flagged by Smatch.

IS_ERR_OR_NULL() gets IS_ERR() in upcoming v4

> 
> > +	}
> > +
> > +	hid_hw_close(hdev);
> > +
> > +	hid_info(hdev, "hexLIN (fw-version: %u) probed\n", priv->fw_version);
> > +
> > +	return 0;
> > +
> > +fail_and_close:
> > +	hid_hw_close(hdev);
> > +fail_and_stop:
> > +	hid_hw_stop(hdev);
> > +fail_and_free:
> > +	mutex_destroy(&priv->tx_lock);
> > +	return ret;
> > +}
> 
> ...

Thanks
  -- Christoph
diff mbox series

Patch

diff --git a/drivers/hid/Kconfig b/drivers/hid/Kconfig
index 4c682c6507040..4caff63d9dcda 100644
--- a/drivers/hid/Kconfig
+++ b/drivers/hid/Kconfig
@@ -496,6 +496,25 @@  config HID_GYRATION
 	help
 	Support for Gyration remote control.
 
+config HID_MCS_HEXDEV
+	tristate "hexDEV LIN-BUS adapter support"
+	depends on HID
+	select CAN_LIN
+	help
+	  Support for hexDEV its hexLIN USB LIN bus adapter.
+
+	  Local Interconnect Network (LIN) to USB adapter for controller and
+	  responder usage.
+	  This device driver is using CAN_LIN for a userland connection on
+	  one side and USB HID for the actual hardware adapter on the other
+	  side.
+
+	  If you have such an adapter, say Y here and see
+	  <https://hexdev.de/hexlin>.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called hid-hexlin.
+
 config HID_ICADE
 	tristate "ION iCade arcade controller"
 	help
diff --git a/drivers/hid/Makefile b/drivers/hid/Makefile
index 082a728eac600..f9b13e6117e60 100644
--- a/drivers/hid/Makefile
+++ b/drivers/hid/Makefile
@@ -59,6 +59,7 @@  obj-$(CONFIG_HID_GOOGLE_STADIA_FF)	+= hid-google-stadiaff.o
 obj-$(CONFIG_HID_VIVALDI)	+= hid-vivaldi.o
 obj-$(CONFIG_HID_GT683R)	+= hid-gt683r.o
 obj-$(CONFIG_HID_GYRATION)	+= hid-gyration.o
+obj-$(CONFIG_HID_MCS_HEXDEV)	+= hid-hexdev-hexlin.o
 obj-$(CONFIG_HID_HOLTEK)	+= hid-holtek-kbd.o
 obj-$(CONFIG_HID_HOLTEK)	+= hid-holtek-mouse.o
 obj-$(CONFIG_HID_HOLTEK)	+= hid-holtekff.o
diff --git a/drivers/hid/hid-hexdev-hexlin.c b/drivers/hid/hid-hexdev-hexlin.c
new file mode 100644
index 0000000000000..34019043f329e
--- /dev/null
+++ b/drivers/hid/hid-hexdev-hexlin.c
@@ -0,0 +1,630 @@ 
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * LIN bus USB adapter driver https://hexdev.de/hexlin
+ *
+ * Copyright (C) 2024 hexDEV GmbH
+ */
+
+#include <linux/module.h>
+#include <linux/wait.h>
+#include <linux/completion.h>
+#include <linux/hid.h>
+#include <net/lin.h>
+#include "hid-ids.h"
+
+enum {
+	/* answers */
+	HEXLIN_SUCCESS = 0x01,
+	HEXLIN_FRAME = 0x02,
+	HEXLIN_ERROR = 0x03,
+	HEXLIN_FAIL = 0x0F,
+
+	/* lin-responder */
+	HEXLIN_SET_MODE_RESPONDER = 0x10,
+	HEXLIN_SET_RESPONDER_ANSWER_ID = 0x11,
+	HEXLIN_GET_RESPONDER_ANSWER_ID = 0x12,
+
+	/* lin-controller */
+	HEXLIN_SET_MODE_CONTROLLER = 0x20,
+	HEXLIN_SEND_BREAK = 0x21,
+	HEXLIN_SEND_UNCONDITIONAL_FRAME = 0x22,
+
+	/* lin-div */
+	HEXLIN_SET_BAUDRATE = 0x34,
+	HEXLIN_GET_BAUDRATE = 0x35,
+
+	/* div */
+	HEXLIN_RESET = 0xF0,
+	HEXLIN_GET_VERSION = 0xF1,
+};
+
+#define HEXLIN_SUCCESS_SZ			1
+#define HEXLIN_FRAME_SZ				17
+#define HEXLIN_FAIL_SZ				1
+#define HEXLIN_GET_RESPONDER_ANSWER_ID_SZ	20
+#define HEXLIN_GET_BAUDRATE_SZ			3
+#define HEXLIN_BAUDRATE_SZ			2
+#define HEXLIN_GET_VERSION_SZ			2
+#define HEXLIN_PKGLEN_MAX_SZ			64
+
+struct hexlin_val8_req {
+	u8 cmd;
+	u8 v;
+} __packed;
+
+struct hexlin_baudrate_req {
+	u8 cmd;
+	u16 baudrate;
+} __packed;
+
+struct hexlin_frame {
+	u32 flags;
+	u8 len;
+	u8 lin_id;
+	u8 data[LIN_MAX_DLEN];
+	u8 checksum;
+	u8 checksum_mode;
+} __packed;
+
+struct hexlin_unconditional_req {
+	u8 cmd;
+	struct hexlin_frame frm;
+} __packed;
+
+struct hexlin_responder_answer {
+	u8 is_active;
+	u8 is_event_frame;
+	u8 event_associated_id;
+	struct hexlin_frame frm;
+} __packed;
+
+struct hexlin_responder_answer_req {
+	u8 cmd;
+	struct hexlin_responder_answer answ;
+} __packed;
+
+struct hexlin_priv_data {
+	struct hid_device *hid_dev;
+	struct lin_device *ldev;
+	u16 baudrate;
+	struct completion wait_in_report;
+	bool is_error;
+	struct mutex tx_lock;  /* protects hexlin_tx_report() */
+	struct hexlin_responder_answer_req rar;
+	u8 fw_version;
+};
+
+static int hexlin_tx_report(struct hexlin_priv_data *priv,
+			    const void *out_report, size_t len)
+{
+	u8 *buf;
+	int ret;
+
+	buf = kmemdup(out_report, len, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	ret = hid_hw_output_report(priv->hid_dev, buf, len);
+	kfree(buf);
+
+	if (ret < 0)
+		return ret;
+	if (ret != len)
+		return -EIO;
+
+	return 0;
+}
+
+static int hexlin_tx_req_status(struct hexlin_priv_data *priv,
+				const void *out_report, int len)
+{
+	int ret;
+	unsigned long t;
+
+	mutex_lock(&priv->tx_lock);
+
+	reinit_completion(&priv->wait_in_report);
+
+	ret = hexlin_tx_report(priv, out_report, len);
+	if (ret)
+		goto tx_exit;
+
+	t = wait_for_completion_killable_timeout(&priv->wait_in_report,
+						 msecs_to_jiffies(1000));
+	if (!t)
+		ret = -ETIMEDOUT;
+
+	if (priv->is_error)
+		ret = -EINVAL;
+
+tx_exit:
+	mutex_unlock(&priv->tx_lock);
+
+	return ret;
+}
+
+#define HEXLIN_GET_CMD(name, enum_cmd)					\
+	static int hexlin_##name(struct hexlin_priv_data *priv)		\
+	{								\
+		u8 cmd = enum_cmd;					\
+		int ret;						\
+									\
+		ret = hexlin_tx_req_status(priv, &cmd, sizeof(u8));	\
+		if (ret)						\
+			hid_err(priv->hid_dev, "%s failed with %d\n",	\
+				__func__, ret);				\
+									\
+		return ret;						\
+	}
+
+HEXLIN_GET_CMD(get_version, HEXLIN_GET_VERSION)
+HEXLIN_GET_CMD(reset_dev, HEXLIN_RESET)
+HEXLIN_GET_CMD(get_baudrate, HEXLIN_GET_BAUDRATE)
+
+#define HEXLIN_VAL_CMD(name, enum_cmd, struct_type, vtype)		\
+	static int hexlin_##name(struct hexlin_priv_data *p, vtype val)	\
+	{								\
+		struct struct_type req;					\
+		int ret;						\
+									\
+		req.cmd = enum_cmd;					\
+		req.v = val;						\
+									\
+		ret = hexlin_tx_req_status(p, &req,			\
+					   sizeof(struct struct_type));	\
+		if (ret)						\
+			hid_err(p->hid_dev, "%s failed with %d\n",	\
+				__func__, ret);				\
+									\
+		return ret;						\
+	}
+
+HEXLIN_VAL_CMD(send_break, HEXLIN_SEND_BREAK, hexlin_val8_req, u8)
+
+static int hexlin_queue_frames_insert(struct hexlin_priv_data *priv,
+				      const u8 *raw_data, int sz)
+{
+	struct hid_device *hdev = priv->hid_dev;
+	struct hexlin_frame hxf;
+	struct lin_frame lf;
+
+	if (sz != sizeof(struct hexlin_frame))
+		return -EREMOTEIO;
+
+	memcpy(&hxf, raw_data, sz);
+	le32_to_cpus(hxf.flags);
+
+	lf.len = hxf.len;
+	lf.lin_id = hxf.lin_id;
+	memcpy(lf.data, hxf.data, LIN_MAX_DLEN);
+	lf.checksum = hxf.checksum;
+	lf.checksum_mode = hxf.checksum_mode;
+
+	hid_dbg(hdev, "id:%02x, len:%u, data:%*ph, checksum:%02x (%s)\n",
+		   lf.lin_id, lf.len, lf.len, lf.data, lf.checksum,
+		   lf.checksum_mode ? "enhanced" : "classic");
+
+	lin_rx(priv->ldev, &lf);
+
+	return 0;
+}
+
+static int hexlin_send_unconditional(struct hexlin_priv_data *priv,
+			      const struct hexlin_frame *hxf)
+{
+	struct hexlin_unconditional_req req;
+	int ret;
+
+	if (hxf->lin_id > LIN_ID_MASK)
+		return -EINVAL;
+
+	req.cmd = HEXLIN_SEND_UNCONDITIONAL_FRAME;
+	memcpy(&req.frm, hxf, sizeof(struct hexlin_frame));
+
+	ret = hexlin_tx_req_status(priv, &req,
+				   sizeof(struct hexlin_unconditional_req));
+
+	if (ret)
+		hid_err(priv->hid_dev, "%s failed with %d\n", __func__, ret);
+
+	return ret;
+}
+
+static int hexlin_set_baudrate(struct hexlin_priv_data *priv, u16 baudrate)
+{
+	struct hexlin_baudrate_req req;
+	int ret;
+
+	if (baudrate < LIN_MIN_BAUDRATE || baudrate > LIN_MAX_BAUDRATE)
+		return -EINVAL;
+
+	req.cmd = HEXLIN_SET_BAUDRATE;
+	req.baudrate = cpu_to_le16(baudrate);
+
+	ret = hexlin_tx_req_status(priv, &req,
+				   sizeof(struct hexlin_baudrate_req));
+	if (ret)
+		hid_err(priv->hid_dev, "%s failed with %d\n", __func__, ret);
+
+	return ret;
+}
+
+static int hexlin_get_responder_answer_id(struct hexlin_priv_data *priv, u8 id,
+					  struct hexlin_responder_answer_req *rar)
+{
+	u8 req[2] = { HEXLIN_GET_RESPONDER_ANSWER_ID, id };
+	int ret;
+
+	if (id > LIN_ID_MASK)
+		return -EINVAL;
+
+	ret = hexlin_tx_req_status(priv, &req, sizeof(req));
+	if (ret) {
+		hid_err(priv->hid_dev, "%s failed with %d\n", __func__, ret);
+		return ret;
+	}
+
+	memcpy(rar, &priv->rar, sizeof(struct hexlin_responder_answer_req));
+
+	return 0;
+}
+
+static int hexlin_set_responder_answer_id(struct hexlin_priv_data *priv,
+					  const struct lin_responder_answer *answ)
+{
+	struct hexlin_responder_answer_req rar;
+	int ret;
+
+	if (answ->lf.lin_id > LIN_ID_MASK ||
+	    answ->event_associated_id > LIN_ID_MASK)
+		return -EINVAL;
+
+	rar.cmd = HEXLIN_SET_RESPONDER_ANSWER_ID;
+	rar.answ.is_active = answ->is_active;
+	rar.answ.is_event_frame = answ->is_event_frame;
+	rar.answ.event_associated_id = answ->event_associated_id;
+	rar.answ.frm.len = answ->lf.len;
+	rar.answ.frm.lin_id = answ->lf.lin_id;
+	memcpy(rar.answ.frm.data, answ->lf.data, LIN_MAX_DLEN);
+	rar.answ.frm.checksum = answ->lf.checksum;
+	rar.answ.frm.checksum_mode = answ->lf.checksum_mode;
+
+	ret = hexlin_tx_req_status(priv, &rar,
+				   sizeof(struct hexlin_responder_answer_req));
+	if (ret)
+		hid_err(priv->hid_dev, "%s failed with %d\n", __func__, ret);
+
+	return ret;
+}
+
+static int hexlin_open(struct lin_device *ldev)
+{
+	struct hid_device *hdev = to_hid_device(ldev->dev);
+
+	return hid_hw_open(hdev);
+}
+
+static int hexlin_stop(struct lin_device *ldev)
+{
+	struct hid_device *hdev = to_hid_device(ldev->dev);
+	struct hexlin_priv_data *priv = hid_get_drvdata(hdev);
+
+	hid_hw_close(hdev);
+
+	priv->is_error = true;
+	complete(&priv->wait_in_report);
+
+	mutex_lock(&priv->tx_lock);
+	mutex_unlock(&priv->tx_lock);
+
+	return 0;
+}
+
+static int hexlin_ldo_tx(struct lin_device *ldev,
+			 const struct lin_frame *lf)
+{
+	struct hid_device *hdev = to_hid_device(ldev->dev);
+	struct hexlin_priv_data *priv = hid_get_drvdata(hdev);
+	int ret = -EINVAL;
+
+	hid_dbg(hdev, "id:%02x, len:%u, data:%*ph, checksum:%02x (%s)\n",
+		   lf->lin_id, lf->len, lf->len, lf->data, lf->checksum,
+		   lf->checksum_mode ? "enhanced" : "classic");
+
+	if (lf->lin_id && lf->len == 0) {
+		ret = hexlin_send_break(priv, lf->lin_id);
+	} else if (lf->len <= LIN_MAX_DLEN) {
+		struct hexlin_frame hxf;
+
+		hxf.len = lf->len;
+		hxf.lin_id = lf->lin_id;
+		memcpy(&hxf.data, lf->data, LIN_MAX_DLEN);
+		hxf.checksum = lf->checksum;
+		hxf.checksum_mode = lf->checksum_mode;
+		ret = hexlin_send_unconditional(priv, &hxf);
+	} else {
+		hid_err(hdev, "unknown format\n");
+	}
+
+	return ret;
+}
+
+static int hexlin_update_bitrate(struct lin_device *ldev, u16 bitrate)
+{
+	struct hid_device *hdev = to_hid_device(ldev->dev);
+	struct hexlin_priv_data *priv = hid_get_drvdata(hdev);
+	int ret;
+
+	hid_dbg(hdev, "update bitrate to: %u\n", bitrate);
+
+	ret = hexlin_open(ldev);
+	if (ret)
+		return ret;
+
+	ret = hexlin_set_baudrate(priv, bitrate);
+	if (ret)
+		return ret;
+
+	ret = hexlin_get_baudrate(priv);
+	if (ret)
+		return ret;
+
+	if (priv->baudrate != bitrate) {
+		hid_err(hdev, "update bitrate failed\n");
+		return -EINVAL;
+	}
+
+	return ret;
+}
+
+static int hexlin_get_responder_answer(struct lin_device *ldev, u8 id,
+				       struct lin_responder_answer *answ)
+{
+	struct hid_device *hdev = to_hid_device(ldev->dev);
+	struct hexlin_priv_data *priv = hid_get_drvdata(hdev);
+	struct hexlin_responder_answer_req rar;
+	int ret;
+
+	if (answ == NULL)
+		return -EINVAL;
+
+	ret = hexlin_get_responder_answer_id(priv, id, &rar);
+	if (ret)
+		return ret;
+
+	answ->is_active = rar.answ.is_active;
+	answ->is_event_frame = rar.answ.is_event_frame;
+	answ->event_associated_id = rar.answ.event_associated_id;
+	answ->lf.len = rar.answ.frm.len;
+	answ->lf.lin_id = rar.answ.frm.lin_id;
+	memcpy(answ->lf.data, rar.answ.frm.data, LIN_MAX_DLEN);
+	answ->lf.checksum = rar.answ.frm.checksum;
+	answ->lf.checksum_mode = rar.answ.frm.checksum_mode;
+
+	return 0;
+}
+
+static int hexlin_update_resp_answer(struct lin_device *ldev,
+				     const struct lin_responder_answer *answ)
+{
+	struct hid_device *hdev = to_hid_device(ldev->dev);
+	struct hexlin_priv_data *priv = hid_get_drvdata(hdev);
+
+	if (answ == NULL)
+		return -EINVAL;
+
+	return hexlin_set_responder_answer_id(priv, answ);
+}
+
+static const struct lin_device_ops hexlin_ldo = {
+	.ldo_open = hexlin_open,
+	.ldo_stop = hexlin_stop,
+	.ldo_tx = hexlin_ldo_tx,
+	.update_bitrate = hexlin_update_bitrate,
+	.get_responder_answer = hexlin_get_responder_answer,
+	.update_responder_answer = hexlin_update_resp_answer,
+};
+
+static int hexlin_raw_event(struct hid_device *hdev,
+			    struct hid_report *report, u8 *data, int sz)
+{
+	struct hexlin_priv_data *priv;
+	int ret;
+
+	if (sz < 1 || sz > HEXLIN_PKGLEN_MAX_SZ)
+		return -EREMOTEIO;
+
+	priv = hid_get_drvdata(hdev);
+
+	hid_dbg(hdev, "%s, size:%i, data[0]: 0x%02x\n", __func__, sz, data[0]);
+
+	priv->is_error = false;
+
+	switch (data[0]) {
+	case HEXLIN_SUCCESS:
+		if (sz != HEXLIN_SUCCESS_SZ)
+			return -EREMOTEIO;
+		hid_dbg(hdev, "HEXLIN_SUCCESS: 0x%02x\n", data[0]);
+		complete(&priv->wait_in_report);
+		break;
+	case HEXLIN_FAIL:
+		if (sz != HEXLIN_FAIL_SZ)
+			return -EREMOTEIO;
+		hid_err(hdev, "HEXLIN_FAIL: 0x%02x\n", data[0]);
+		priv->is_error = true;
+		complete(&priv->wait_in_report);
+		break;
+	case HEXLIN_GET_VERSION:
+		if (sz != HEXLIN_GET_VERSION_SZ)
+			return -EREMOTEIO;
+		priv->fw_version = data[1];
+		complete(&priv->wait_in_report);
+		break;
+	case HEXLIN_GET_RESPONDER_ANSWER_ID:
+		if (sz != HEXLIN_GET_RESPONDER_ANSWER_ID_SZ)
+			return -EREMOTEIO;
+		BUILD_BUG_ON(sizeof(priv->rar) !=
+			HEXLIN_GET_RESPONDER_ANSWER_ID_SZ);
+		memcpy(&priv->rar, data, sizeof(priv->rar));
+		complete(&priv->wait_in_report);
+		break;
+	case HEXLIN_GET_BAUDRATE:
+		if (sz != HEXLIN_GET_BAUDRATE_SZ)
+			return -EREMOTEIO;
+		BUILD_BUG_ON(sizeof(priv->baudrate) != HEXLIN_BAUDRATE_SZ);
+		memcpy(&priv->baudrate, &data[1], sizeof(priv->baudrate));
+		le16_to_cpus(priv->baudrate);
+		complete(&priv->wait_in_report);
+		break;
+	/* following cases not initiated by us, so no complete() */
+	case HEXLIN_FRAME:
+		if (sz != HEXLIN_FRAME_SZ) {
+			hid_err_once(hdev, "frame size mismatch: %i\n", sz);
+			return -EREMOTEIO;
+		}
+		ret = hexlin_queue_frames_insert(priv, &data[1], sz-1);
+		if (ret) {
+			hid_err(hdev, "failed to add frame: %i\n", ret);
+			return ret;
+		}
+		break;
+	case HEXLIN_ERROR:
+		hid_err(hdev, "error from adapter\n");
+		break;
+	default:
+		hid_err(hdev, "unknown event: 0x%02x\n", data[0]);
+	}
+
+	return 0;
+}
+
+static int init_hw(struct hexlin_priv_data *priv)
+{
+	u8 dummy[] = { 0 };
+	int ret;
+
+	ret = hexlin_tx_report(priv, dummy, 1);
+	if (ret)
+		return ret;
+
+	ret = hexlin_reset_dev(priv);
+	if (ret)
+		return ret;
+
+	ret = hexlin_get_version(priv);
+	if (ret)
+		return ret;
+
+	priv->baudrate = LIN_DEFAULT_BAUDRATE;
+	ret = hexlin_set_baudrate(priv, priv->baudrate);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static int hexlin_probe(struct hid_device *hdev,
+			const struct hid_device_id *id)
+{
+	struct hexlin_priv_data *priv;
+	int ret;
+
+	priv = devm_kzalloc(&hdev->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->hid_dev = hdev;
+	hid_set_drvdata(hdev, priv);
+
+	mutex_init(&priv->tx_lock);
+
+	ret = hid_parse(hdev);
+	if (ret) {
+		hid_err(hdev, "hid parse failed with %d\n", ret);
+		goto fail_and_free;
+	}
+
+	ret = hid_hw_start(hdev, HID_CONNECT_DRIVER);
+	if (ret) {
+		hid_err(hdev, "hid hw start failed with %d\n", ret);
+		goto fail_and_stop;
+	}
+
+	ret = hid_hw_open(hdev);
+	if (ret) {
+		hid_err(hdev, "hid hw open failed with %d\n", ret);
+		goto fail_and_close;
+	}
+
+	init_completion(&priv->wait_in_report);
+
+	hid_device_io_start(hdev);
+
+	ret = init_hw(priv);
+	if (ret)
+		goto fail_and_close;
+
+	priv->ldev = register_lin(&hdev->dev, &hexlin_ldo);
+	if (IS_ERR_OR_NULL(priv->ldev)) {
+		ret = PTR_ERR(priv->ldev);
+		goto fail_and_close;
+	}
+
+	hid_hw_close(hdev);
+
+	hid_info(hdev, "hexLIN (fw-version: %u) probed\n", priv->fw_version);
+
+	return 0;
+
+fail_and_close:
+	hid_hw_close(hdev);
+fail_and_stop:
+	hid_hw_stop(hdev);
+fail_and_free:
+	mutex_destroy(&priv->tx_lock);
+	return ret;
+}
+
+static void hexlin_remove(struct hid_device *hdev)
+{
+	struct hexlin_priv_data *priv = hid_get_drvdata(hdev);
+
+	unregister_lin(priv->ldev);
+	hid_hw_stop(hdev);
+	mutex_destroy(&priv->tx_lock);
+}
+
+static const struct hid_device_id hexlin_table[] = {
+	{ HID_USB_DEVICE(USB_VENDOR_ID_MCS, USB_DEVICE_ID_MCS_HEXDEV_HEXLIN) },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(hid, hexlin_table);
+
+static struct hid_driver hexlin_driver = {
+	.name = "hexLIN",
+	.id_table = hexlin_table,
+	.probe = hexlin_probe,
+	.remove = hexlin_remove,
+	.raw_event = hexlin_raw_event,
+};
+
+static int __init hexlin_init(void)
+{
+	return hid_register_driver(&hexlin_driver);
+}
+
+static void __exit hexlin_exit(void)
+{
+	hid_unregister_driver(&hexlin_driver);
+}
+
+/*
+ * When compiled into the kernel, initialize after the hid bus.
+ */
+late_initcall(hexlin_init);
+module_exit(hexlin_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Christoph Fritz <christoph.fritz@hexdev.de>");
+MODULE_DESCRIPTION("LIN bus driver for hexLIN USB adapter");
diff --git a/drivers/hid/hid-ids.h b/drivers/hid/hid-ids.h
index 64164423b592b..8f46d37c2b499 100644
--- a/drivers/hid/hid-ids.h
+++ b/drivers/hid/hid-ids.h
@@ -907,6 +907,7 @@ 
 
 #define USB_VENDOR_ID_MCS		0x16d0
 #define USB_DEVICE_ID_MCS_GAMEPADBLOCK	0x0bcc
+#define USB_DEVICE_ID_MCS_HEXDEV_HEXLIN	0x0648
 
 #define USB_VENDOR_MEGAWORLD		0x07b5
 #define USB_DEVICE_ID_MEGAWORLD_GAMEPAD	0x0312
diff --git a/drivers/hid/hid-quirks.c b/drivers/hid/hid-quirks.c
index 1d1949d62dfaf..a514449c50047 100644
--- a/drivers/hid/hid-quirks.c
+++ b/drivers/hid/hid-quirks.c
@@ -438,6 +438,9 @@  static const struct hid_device_id hid_have_special_driver[] = {
 	{ HID_USB_DEVICE(USB_VENDOR_ID_GYRATION, USB_DEVICE_ID_GYRATION_REMOTE_2) },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_GYRATION, USB_DEVICE_ID_GYRATION_REMOTE_3) },
 #endif
+#if IS_ENABLED(CONFIG_HID_MCS_HEXDEV)
+	{ HID_USB_DEVICE(USB_VENDOR_ID_MCS, USB_DEVICE_ID_MCS_HEXDEV_HEXLIN) },
+#endif
 #if IS_ENABLED(CONFIG_HID_HOLTEK)
 	{ HID_USB_DEVICE(USB_VENDOR_ID_HOLTEK, USB_DEVICE_ID_HOLTEK_ON_LINE_GRIP) },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_HOLTEK_ALT, USB_DEVICE_ID_HOLTEK_ALT_KEYBOARD) },