can: janz-ican3: fix support for CAN_RAW_RECV_OWN_MSGS
The Janz VMOD-ICAN3 firmware does not support any sort of TX-done
notification or interrupt. The driver previously used the hardware
loopback to attempt to work around this deficiency, but this caused all
sockets to receive all messages, even if CAN_RAW_RECV_OWN_MSGS is off.
Using the new function ican3_cmp_echo_skb(), we can drop the loopback
messages and return the original skbs. This fixes the issues with
CAN_RAW_RECV_OWN_MSGS.
A private skb queue is used to store the echo skbs. This avoids the need
for any index management.
Due to a lack of TX-error interrupts, bus errors are permanently
enabled, and are used as a TX-error notification. This is used to drop
an echo skb when transmission fails. Bus error packets are not generated
if the user has not enabled bus error reporting.
Signed-off-by: Ira W. Snyder <iws@ovro.caltech.edu>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
diff --git a/drivers/net/can/janz-ican3.c b/drivers/net/can/janz-ican3.c
index 4a5a8fb..47f8f6b 100644
--- a/drivers/net/can/janz-ican3.c
+++ b/drivers/net/can/janz-ican3.c
@@ -220,6 +220,9 @@
/* old and new style host interface */
unsigned int iftype;
+ /* queue for echo packets */
+ struct sk_buff_head echoq;
+
/*
* Any function which changes the current DPM page must hold this
* lock while it is performing data accesses. This ensures that the
@@ -925,7 +928,7 @@
struct net_device *dev = mod->ndev;
struct net_device_stats *stats = &dev->stats;
enum can_state state = mod->can.state;
- u8 status, isrc, rxerr, txerr;
+ u8 isrc, ecc, status, rxerr, txerr;
struct can_frame *cf;
struct sk_buff *skb;
@@ -941,15 +944,43 @@
return -EINVAL;
}
- skb = alloc_can_err_skb(dev, &cf);
- if (skb == NULL)
- return -ENOMEM;
-
isrc = msg->data[0];
+ ecc = msg->data[2];
status = msg->data[3];
rxerr = msg->data[4];
txerr = msg->data[5];
+ /*
+ * This hardware lacks any support other than bus error messages to
+ * determine if packet transmission has failed.
+ *
+ * When TX errors happen, one echo skb needs to be dropped from the
+ * front of the queue.
+ *
+ * A small bit of code is duplicated here and below, to avoid error
+ * skb allocation when it will just be freed immediately.
+ */
+ if (isrc == CEVTIND_BEI) {
+ int ret;
+ dev_dbg(mod->dev, "bus error interrupt\n");
+
+ /* TX error */
+ if (!(ecc & ECC_DIR)) {
+ kfree_skb(skb_dequeue(&mod->echoq));
+ stats->tx_errors++;
+ } else {
+ stats->rx_errors++;
+ }
+
+ /* bus error reporting is off, return immediately */
+ if (!(mod->can.ctrlmode & CAN_CTRLMODE_BERR_REPORTING))
+ return 0;
+ }
+
+ skb = alloc_can_err_skb(dev, &cf);
+ if (skb == NULL)
+ return -ENOMEM;
+
/* data overrun interrupt */
if (isrc == CEVTIND_DOI || isrc == CEVTIND_LOST) {
dev_dbg(mod->dev, "data overrun interrupt\n");
@@ -978,9 +1009,6 @@
/* bus error interrupt */
if (isrc == CEVTIND_BEI) {
- u8 ecc = msg->data[2];
-
- dev_dbg(mod->dev, "bus error interrupt\n");
mod->can.can_stats.bus_error++;
cf->can_id |= CAN_ERR_PROT | CAN_ERR_BUSERROR;
@@ -1000,12 +1028,8 @@
break;
}
- if (!(ecc & ECC_DIR)) {
+ if (!(ecc & ECC_DIR))
cf->data[2] |= CAN_ERR_PROT_TX;
- stats->tx_errors++;
- } else {
- stats->rx_errors++;
- }
cf->data[6] = txerr;
cf->data[7] = rxerr;
@@ -1090,6 +1114,88 @@
}
/*
+ * The ican3 needs to store all echo skbs, and therefore cannot
+ * use the generic infrastructure for this.
+ */
+static void ican3_put_echo_skb(struct ican3_dev *mod, struct sk_buff *skb)
+{
+ struct sock *srcsk = skb->sk;
+
+ if (atomic_read(&skb->users) != 1) {
+ struct sk_buff *old_skb = skb;
+
+ skb = skb_clone(old_skb, GFP_ATOMIC);
+ kfree_skb(old_skb);
+ if (!skb)
+ return;
+ } else {
+ skb_orphan(skb);
+ }
+
+ skb->sk = srcsk;
+
+ /* save this skb for tx interrupt echo handling */
+ skb_queue_tail(&mod->echoq, skb);
+}
+
+static unsigned int ican3_get_echo_skb(struct ican3_dev *mod)
+{
+ struct sk_buff *skb = skb_dequeue(&mod->echoq);
+ struct can_frame *cf;
+ u8 dlc;
+
+ /* this should never trigger unless there is a driver bug */
+ if (!skb) {
+ netdev_err(mod->ndev, "BUG: echo skb not occupied\n");
+ return 0;
+ }
+
+ cf = (struct can_frame *)skb->data;
+ dlc = cf->can_dlc;
+
+ /* check flag whether this packet has to be looped back */
+ if (skb->pkt_type != PACKET_LOOPBACK) {
+ kfree_skb(skb);
+ return dlc;
+ }
+
+ skb->protocol = htons(ETH_P_CAN);
+ skb->pkt_type = PACKET_BROADCAST;
+ skb->ip_summed = CHECKSUM_UNNECESSARY;
+ skb->dev = mod->ndev;
+ netif_receive_skb(skb);
+ return dlc;
+}
+
+/*
+ * Compare an skb with an existing echo skb
+ *
+ * This function will be used on devices which have a hardware loopback.
+ * On these devices, this function can be used to compare a received skb
+ * with the saved echo skbs so that the hardware echo skb can be dropped.
+ *
+ * Returns true if the skb's are identical, false otherwise.
+ */
+static bool ican3_echo_skb_matches(struct ican3_dev *mod, struct sk_buff *skb)
+{
+ struct can_frame *cf = (struct can_frame *)skb->data;
+ struct sk_buff *echo_skb = skb_peek(&mod->echoq);
+ struct can_frame *echo_cf;
+
+ if (!echo_skb)
+ return false;
+
+ echo_cf = (struct can_frame *)echo_skb->data;
+ if (cf->can_id != echo_cf->can_id)
+ return false;
+
+ if (cf->can_dlc != echo_cf->can_dlc)
+ return false;
+
+ return memcmp(cf->data, echo_cf->data, cf->can_dlc) == 0;
+}
+
+/*
* Check that there is room in the TX ring to transmit another skb
*
* LOCKING: must hold mod->lock
@@ -1099,6 +1205,10 @@
struct ican3_fast_desc __iomem *desc;
u8 control;
+ /* check that we have echo queue space */
+ if (skb_queue_len(&mod->echoq) >= ICAN3_TX_BUFFERS)
+ return false;
+
/* copy the control bits of the descriptor */
ican3_set_page(mod, mod->fasttx_start + (mod->fasttx_num / 16));
desc = mod->dpm + ((mod->fasttx_num % 16) * sizeof(*desc));
@@ -1149,10 +1259,27 @@
/* convert the ICAN3 frame into Linux CAN format */
ican3_to_can_frame(mod, &desc, cf);
- /* receive the skb, update statistics */
- netif_receive_skb(skb);
+ /*
+ * If this is an ECHO frame received from the hardware loopback
+ * feature, use the skb saved in the ECHO stack instead. This allows
+ * the Linux CAN core to support CAN_RAW_RECV_OWN_MSGS correctly.
+ *
+ * Since this is a confirmation of a successfully transmitted packet
+ * sent from this host, update the transmit statistics.
+ *
+ * Also, the netdevice queue needs to be allowed to send packets again.
+ */
+ if (ican3_echo_skb_matches(mod, skb)) {
+ stats->tx_packets++;
+ stats->tx_bytes += ican3_get_echo_skb(mod);
+ kfree_skb(skb);
+ goto err_noalloc;
+ }
+
+ /* update statistics, receive the skb */
stats->rx_packets++;
stats->rx_bytes += cf->can_dlc;
+ netif_receive_skb(skb);
err_noalloc:
/* toggle the valid bit and return the descriptor to the ring */
@@ -1175,13 +1302,13 @@
static int ican3_napi(struct napi_struct *napi, int budget)
{
struct ican3_dev *mod = container_of(napi, struct ican3_dev, napi);
- struct ican3_msg msg;
unsigned long flags;
int received = 0;
int ret;
/* process all communication messages */
while (true) {
+ struct ican3_msg msg;
ret = ican3_recv_msg(mod, &msg);
if (ret)
break;
@@ -1353,7 +1480,6 @@
static int ican3_open(struct net_device *ndev)
{
struct ican3_dev *mod = netdev_priv(ndev);
- u8 quota;
int ret;
/* open the CAN layer */
@@ -1363,19 +1489,6 @@
return ret;
}
- /* set the bus error generation state appropriately */
- if (mod->can.ctrlmode & CAN_CTRLMODE_BERR_REPORTING)
- quota = ICAN3_BUSERR_QUOTA_MAX;
- else
- quota = 0;
-
- ret = ican3_set_buserror(mod, quota);
- if (ret) {
- dev_err(mod->dev, "unable to set bus-error\n");
- close_candev(ndev);
- return ret;
- }
-
/* bring the bus online */
ret = ican3_set_bus_state(mod, true);
if (ret) {
@@ -1407,6 +1520,9 @@
return ret;
}
+ /* drop all outstanding echo skbs */
+ skb_queue_purge(&mod->echoq);
+
/* close the CAN layer */
close_candev(ndev);
return 0;
@@ -1415,7 +1531,6 @@
static int ican3_xmit(struct sk_buff *skb, struct net_device *ndev)
{
struct ican3_dev *mod = netdev_priv(ndev);
- struct net_device_stats *stats = &ndev->stats;
struct can_frame *cf = (struct can_frame *)skb->data;
struct ican3_fast_desc desc;
void __iomem *desc_addr;
@@ -1428,8 +1543,7 @@
/* check that we can actually transmit */
if (!ican3_txok(mod)) {
- dev_err(mod->dev, "no free descriptors, stopping queue\n");
- netif_stop_queue(ndev);
+ dev_err(mod->dev, "BUG: no free descriptors\n");
spin_unlock_irqrestore(&mod->lock, flags);
return NETDEV_TX_BUSY;
}
@@ -1444,6 +1558,14 @@
can_frame_to_ican3(mod, cf, &desc);
/*
+ * This hardware doesn't have TX-done notifications, so we'll try and
+ * emulate it the best we can using ECHO skbs. Add the skb to the ECHO
+ * stack. Upon packet reception, check if the ECHO skb and received
+ * skb match, and use that to wake the queue.
+ */
+ ican3_put_echo_skb(mod, skb);
+
+ /*
* the programming manual says that you must set the IVALID bit, then
* interrupt, then set the valid bit. Quite weird, but it seems to be
* required for this to work
@@ -1461,19 +1583,7 @@
mod->fasttx_num = (desc.control & DESC_WRAP) ? 0
: (mod->fasttx_num + 1);
- /* update statistics */
- stats->tx_packets++;
- stats->tx_bytes += cf->can_dlc;
- kfree_skb(skb);
-
- /*
- * This hardware doesn't have TX-done notifications, so we'll try and
- * emulate it the best we can using ECHO skbs. Get the next TX
- * descriptor, and see if we have room to send. If not, stop the queue.
- * It will be woken when the ECHO skb for the current packet is recv'd.
- */
-
- /* copy the control bits of the descriptor */
+ /* if there is no free descriptor space, stop the transmit queue */
if (!ican3_txok(mod))
netif_stop_queue(ndev);
@@ -1669,6 +1779,7 @@
mod->dev = &pdev->dev;
mod->num = pdata->modno;
netif_napi_add(ndev, &mod->napi, ican3_napi, ICAN3_RX_BUFFERS);
+ skb_queue_head_init(&mod->echoq);
spin_lock_init(&mod->lock);
init_completion(&mod->termination_comp);
init_completion(&mod->buserror_comp);