netdev - [PATCH v4 08/11] can: bcm: Add LIN answer offloading for responder mode

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Message-Id: <20240509171736.2048414-9-christoph.fritz@hexdev.de>
Date: Thu,  9 May 2024 19:17:33 +0200
From: Christoph Fritz <christoph.fritz@...dev.de>
To: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>,
	Jiri Slaby <jirislaby@...nel.org>,
	Simon Horman <horms@...nel.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Marc Kleine-Budde <mkl@...gutronix.de>,
	Oliver Hartkopp <socketcan@...tkopp.net>,
	Vincent Mailhol <mailhol.vincent@...adoo.fr>,
	"David S . Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Jiri Kosina <jikos@...nel.org>,
	Benjamin Tissoires <bentiss@...nel.org>,
	Sebastian Reichel <sre@...nel.org>,
	Linus Walleij <linus.walleij@...aro.org>
Cc: Andreas Lauser <andreas.lauser@...cedes-benz.com>,
	Jonathan Corbet <corbet@....net>,
	Pavel Pisa <pisa@....felk.cvut.cz>,
	linux-can@...r.kernel.org,
	netdev@...r.kernel.org,
	devicetree@...r.kernel.org,
	linux-input@...r.kernel.org,
	linux-serial@...r.kernel.org
Subject: [PATCH v4 08/11] can: bcm: Add LIN answer offloading for responder mode

Enhance CAN broadcast manager with RX_LIN_SETUP and RX_LIN_DELETE
operations to setup automatic LIN frame responses in responder mode.

Additionally, the patch introduces the LIN_EVENT_FRAME flag to
setup event-triggered LIN frames.

Signed-off-by: Christoph Fritz <christoph.fritz@...dev.de>
---
 include/uapi/linux/can/bcm.h |  5 ++-
 net/can/bcm.c                | 72 ++++++++++++++++++++++++++++++++++++
 2 files changed, 76 insertions(+), 1 deletion(-)

diff --git a/include/uapi/linux/can/bcm.h b/include/uapi/linux/can/bcm.h
index f1e45f533a72c..d27bc79f924c1 100644
--- a/include/uapi/linux/can/bcm.h
+++ b/include/uapi/linux/can/bcm.h
@@ -86,7 +86,9 @@ enum {
 	TX_EXPIRED,	/* notification on performed transmissions (count=0) */
 	RX_STATUS,	/* reply to RX_READ request */
 	RX_TIMEOUT,	/* cyclic message is absent */
-	RX_CHANGED	/* updated CAN frame (detected content change) */
+	RX_CHANGED,	/* updated CAN frame (detected content change) */
+	RX_LIN_SETUP,	/* create auto-response for LIN frame */
+	RX_LIN_DELETE,  /* remove auto-response for LIN frame */
 };
 
 #define SETTIMER            0x0001
@@ -101,5 +103,6 @@ enum {
 #define TX_RESET_MULTI_IDX  0x0200
 #define RX_RTR_FRAME        0x0400
 #define CAN_FD_FRAME        0x0800
+#define LIN_EVENT_FRAME     BIT(12)
 
 #endif /* !_UAPI_CAN_BCM_H */
diff --git a/net/can/bcm.c b/net/can/bcm.c
index 27d5fcf0eac9d..6dc8b9877db4c 100644
--- a/net/can/bcm.c
+++ b/net/can/bcm.c
@@ -59,6 +59,7 @@
 #include <linux/can/bcm.h>
 #include <linux/slab.h>
 #include <net/sock.h>
+#include <net/lin.h>
 #include <net/net_namespace.h>
 
 /*
@@ -1330,6 +1331,59 @@ static int bcm_tx_send(struct msghdr *msg, int ifindex, struct sock *sk,
 	return cfsiz + MHSIZ;
 }
 
+static int bcm_lin_setup(struct bcm_msg_head *msg_head, struct msghdr *msg,
+			 int ifindex, struct sock *sk, int cfsiz, int is_active)
+{
+	struct lin_responder_answer answ;
+	struct net_device *dev;
+	struct sk_buff *skb;
+	struct canfd_frame cf;
+	netdevice_tracker tracker;
+	size_t sz;
+	int ret;
+
+	if (msg_head->nframes > 1)
+		return -EINVAL;
+
+	if (!(msg_head->flags & CAN_FD_FRAME))
+		return -EINVAL;
+
+	ret = memcpy_from_msg(&cf, msg, cfsiz);
+	if (ret < 0)
+		return ret;
+
+	answ.lf.lin_id = cf.can_id & LIN_ID_MASK;
+	answ.is_active = is_active;
+	answ.is_event_frame = !!(msg_head->flags & LIN_EVENT_FRAME);
+	answ.event_associated_id = msg_head->can_id;
+	answ.lf.len = min(cf.len, LIN_MAX_DLEN);
+	memcpy(answ.lf.data, cf.data, answ.lf.len);
+	sz = min(sizeof(struct lin_responder_answer), sizeof(cf.data));
+	cf.can_id |= LIN_RXOFFLOAD_DATA_FLAG;
+	memcpy(cf.data, &answ, sz);
+
+	dev = netdev_get_by_index(sock_net(sk), ifindex, &tracker, gfp_any());
+	if (!dev)
+		return -ENODEV;
+
+	skb = alloc_skb(cfsiz + sizeof(struct can_skb_priv), gfp_any());
+	if (!skb)
+		goto lin_out;
+
+	can_skb_reserve(skb);
+	can_skb_prv(skb)->ifindex = dev->ifindex;
+	can_skb_prv(skb)->skbcnt = 0;
+	skb_put_data(skb, &cf, cfsiz);
+
+	skb->dev = dev;
+	can_skb_set_owner(skb, sk);
+	ret = can_send(skb, 1); /* send with loopback */
+
+lin_out:
+	netdev_put(dev, &tracker);
+	return ret;
+}
+
 /*
  * bcm_sendmsg - process BCM commands (opcodes) from the userspace
  */
@@ -1435,6 +1489,24 @@ static int bcm_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)
 			ret = bcm_tx_send(msg, ifindex, sk, cfsiz);
 		break;
 
+	case RX_LIN_SETUP:
+		/* we need exactly one CAN frame behind the msg head */
+		if (msg_head.nframes != 1 || size != cfsiz + MHSIZ)
+			ret = -EINVAL;
+		else
+			ret = bcm_lin_setup(&msg_head, msg, ifindex, sk, cfsiz,
+					    1);
+		break;
+
+	case RX_LIN_DELETE:
+		/* we need exactly one CAN frame behind the msg head */
+		if (msg_head.nframes != 1 || size != cfsiz + MHSIZ)
+			ret = -EINVAL;
+		else
+			ret = bcm_lin_setup(&msg_head, msg, ifindex, sk, cfsiz,
+					    0);
+		break;
+
 	default:
 		ret = -EINVAL;
 		break;
-- 
2.39.2