[PATCH v4 09/11] can: lin: Handle rx offload config frames

[Christoph Fritz <christoph.fritz@hexdev.de>]

The CAN Broadcast Manager now has the capability to dispatch CANFD
frames marked with the id LINBUS_RXOFFLOAD_ID.

Introduce functionality to interpret these specific frames, enabling the
configuration of RX offloading within the LIN driver.

Signed-off-by: Christoph Fritz <christoph.fritz@hexdev.de>
---
 drivers/net/can/lin.c | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/drivers/net/can/lin.c b/drivers/net/can/lin.c
index a22768c17e3f8..f77abd7d7d21c 100644
--- a/drivers/net/can/lin.c
+++ b/drivers/net/can/lin.c
@@ -185,6 +185,27 @@ static const struct attribute_group lin_sysfs_group = {
 	.attrs = lin_sysfs_attrs,
 };
 
+static int lin_setup_rxoffload(struct lin_device *ldev,
+			       struct canfd_frame *cfd)
+{
+	struct lin_responder_answer answ;
+
+	if (!(cfd->flags & CANFD_FDF))
+		return -EINVAL;
+
+	BUILD_BUG_ON(sizeof(answ) > sizeof(cfd->data));
+	memcpy(&answ, cfd->data, sizeof(answ));
+
+	answ.lf.checksum_mode = (cfd->can_id & LIN_ENHANCED_CKSUM_FLAG) ?
+			LINBUS_ENHANCED : LINBUS_CLASSIC;
+
+	if (answ.lf.lin_id > LIN_ID_MASK ||
+	    answ.event_associated_id > LIN_ID_MASK)
+		return -EINVAL;
+
+	return ldev->ldev_ops->update_responder_answer(ldev, &answ);
+}
+
 static void lin_tx_work_handler(struct work_struct *ws)
 {
 	struct lin_device *ldev = container_of(ws, struct lin_device,
@@ -197,6 +218,14 @@ static void lin_tx_work_handler(struct work_struct *ws)
 	ldev->tx_busy = true;
 
 	cfd = (struct canfd_frame *)ldev->tx_skb->data;
+
+	if (cfd->can_id & LIN_RXOFFLOAD_DATA_FLAG) {
+		ret = lin_setup_rxoffload(ldev, cfd);
+		if (ret < 0)
+			netdev_err(ndev, "setting up rx failed %d\n", ret);
+		goto lin_tx_out;
+	}
+
 	lf.checksum_mode = (cfd->can_id & LIN_ENHANCED_CKSUM_FLAG) ?
 			   LINBUS_ENHANCED : LINBUS_CLASSIC;
 	lf.lin_id = cfd->can_id & LIN_ID_MASK;
-- 
2.39.2