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Message-ID: <20251118092115.3455-11-arun.muthusamy@gaisler.com>
Date: Tue, 18 Nov 2025 10:21:15 +0100
From: Arun Muthusamy <arun.muthusamy@...sler.com>
To: robh@...nel.org,
krzk+dt@...nel.org,
conor+dt@...nel.org,
mkl@...gutronix.de,
mailhol@...nel.org
Cc: devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org,
linux-can@...r.kernel.org,
Arun Muthusamy <arun.muthusamy@...sler.com>
Subject: [PATCH 10/10] can: grcan: Add CANFD support alongside legacy CAN
Include CANFD support with the legacy CAN support, enabling
support for extended data payloads up to 64 bytes, higher bit rates,
handle canecho frames.
Signed-off-by: Arun Muthusamy <arun.muthusamy@...sler.com>
---
drivers/net/can/grcan.c | 240 ++++++++++++++++++++++++++++------------
1 file changed, 167 insertions(+), 73 deletions(-)
diff --git a/drivers/net/can/grcan.c b/drivers/net/can/grcan.c
index 8753bff4f917..ff7ab979d2c9 100644
--- a/drivers/net/can/grcan.c
+++ b/drivers/net/can/grcan.c
@@ -44,6 +44,8 @@
#define GRCAN_RESERVE_SIZE(slot1, slot2) (((slot2) - (slot1)) / 4 - 1)
+#define CHECK_SLOT_FDF(slot) ((slot) & GRCAN_RX_FDF)
+
struct grcan_registers {
u32 conf; /* 0x00 */
u32 stat; /* 0x04 */
@@ -181,8 +183,11 @@ struct grcan_registers {
| GRCAN_IRQ_TXAHBERR | GRCAN_IRQ_RXAHBERR \
| GRCAN_IRQ_TXLOSS)
#define GRCAN_IRQ_DEFAULT (GRCAN_IRQ_RX | GRCAN_IRQ_TX | GRCAN_IRQ_ERRORS)
+#define GRCAN_CTRL_MODES (CAN_CTRLMODE_LISTENONLY | CAN_CTRLMODE_ONE_SHOT)
+#define GRCAN_CTRL_MODES_FD (CAN_CTRLMODE_LISTENONLY | CAN_CTRLMODE_ONE_SHOT | CAN_CTRLMODE_FD)
#define GRCAN_MSG_SIZE 16
+#define GRCAN_CLASSIC_DATA_SIZE 8
#define GRCAN_MSG_IDE 0x80000000
#define GRCAN_MSG_RTR 0x40000000
@@ -264,6 +269,12 @@ struct grcan_registers {
#define GRCANFD_FDBTR_PS2_BIT 5
#define GRCANFD_FDBTR_SJW_BIT 0
+#define GRCAN_TX_BRS BIT(25)
+#define GRCAN_TX_FDF BIT(26)
+
+#define GRCAN_RX_BRS BIT(25)
+#define GRCAN_RX_FDF BIT(26)
+
/* Hardware capabilities */
struct grcan_hwcap {
/* CAN-FD capable, indicates GRCANFD IP.
@@ -326,6 +337,13 @@ struct grcan_priv {
struct sk_buff **echo_skb; /* We allocate this on our own */
+ /*
+ * Since the CAN FD frame has a variable length, this variable is used
+ * to keep track of the index of the CAN echo skb (socket buffer) frame.
+ * It's important for ensuring that we correctly manage the echo skb.
+ */
+ u32 echo_skb_idx;
+
/* The echo skb pointer, pointing into echo_skb and indicating which
* frames can be echoed back. See the "Notes on the tx cyclic buffer
* handling"-comment for grcan_start_xmit for more details.
@@ -637,7 +655,7 @@ static int catch_up_echo_skb(struct net_device *dev, int budget, bool echo)
struct grcan_registers __iomem *regs = priv->regs;
struct grcan_dma *dma = &priv->dma;
struct net_device_stats *stats = &dev->stats;
- int i, work_done;
+ int work_done;
/* Updates to priv->eskbp and wake-ups of the queue needs to
* be atomic towards the reads of priv->eskbp and shut-downs
@@ -648,19 +666,22 @@ static int catch_up_echo_skb(struct net_device *dev, int budget, bool echo)
for (work_done = 0; work_done < budget || budget < 0; work_done++) {
if (priv->eskbp == txrd)
break;
- i = priv->eskbp / GRCAN_MSG_SIZE;
- if (echo) {
- /* Normal echo of messages */
- stats->tx_packets++;
- stats->tx_bytes += can_get_echo_skb(dev, i, NULL);
- } else {
- /* For cleanup of untransmitted messages */
- can_free_echo_skb(dev, i, NULL);
- }
priv->eskbp = grcan_ring_add(priv->eskbp, GRCAN_MSG_SIZE,
dma->tx.size);
txrd = grcan_read_reg(®s->txrd);
+
+ /* Grab the packet once the packet is send or free untransmitted packet*/
+ if (priv->eskbp == txrd) {
+ if (echo) {
+ /* Normal echo of messages */
+ stats->tx_packets++;
+ stats->tx_bytes += can_get_echo_skb(dev, priv->echo_skb_idx, NULL);
+ } else {
+ /* For cleanup of untransmitted messages */
+ can_free_echo_skb(dev, priv->echo_skb_idx, NULL);
+ }
+ }
}
return work_done;
}
@@ -1174,6 +1195,7 @@ static int grcan_set_mode(struct net_device *dev, enum can_mode mode)
if (!(priv->can.ctrlmode & CAN_CTRLMODE_LISTENONLY))
netif_wake_queue(dev);
}
+ priv->echo_skb_idx = 0;
spin_unlock_irqrestore(&priv->lock, flags);
return err;
}
@@ -1223,7 +1245,6 @@ static int grcan_open(struct net_device *dev)
netif_start_queue(dev);
priv->resetting = false;
priv->closing = false;
-
spin_unlock_irqrestore(&priv->lock, flags);
return 0;
@@ -1294,20 +1315,29 @@ static void grcan_transmit_catch_up(struct net_device *dev)
spin_unlock_irqrestore(&priv->lock, flags);
}
+static int grcan_numbds(int len)
+{
+ if (len <= GRCAN_CLASSIC_DATA_SIZE)
+ return 1;
+ return 1 + ((len - GRCAN_CLASSIC_DATA_SIZE + GRCAN_MSG_SIZE) / GRCAN_MSG_SIZE);
+}
+
static int grcan_receive(struct net_device *dev, int budget)
{
struct grcan_priv *priv = netdev_priv(dev);
struct grcan_registers __iomem *regs = priv->regs;
struct grcan_dma *dma = &priv->dma;
struct net_device_stats *stats = &dev->stats;
- struct can_frame *cf;
+ struct canfd_frame *cf;
struct sk_buff *skb;
- u32 wr, rd, startrd;
+ u32 wr, rd, dlc, startrd;
u32 *slot;
u32 rtr, eff;
- int work_done = 0;
+ u8 *data;
+ int i, bds, payload_offset, copy_len, work_done = 0;
rd = grcan_read_reg(®s->rxrd);
+
startrd = rd;
for (work_done = 0; work_done < budget; work_done++) {
/* Check for packet to receive */
@@ -1315,44 +1345,70 @@ static int grcan_receive(struct net_device *dev, int budget)
if (rd == wr)
break;
- /* Take care of packet */
- skb = alloc_can_skb(dev, &cf);
- if (skb == NULL) {
+ slot = dma->rx.buf + rd;
+
+ if (CHECK_SLOT_FDF(slot[1]))
+ skb = alloc_canfd_skb(dev, &cf);
+ else
+ skb = alloc_can_skb(priv->dev, (struct can_frame **)&cf);
+
+ if (unlikely(!skb)) {
netdev_err(dev,
"dropping frame: skb allocation failed\n");
stats->rx_dropped++;
continue;
}
- slot = dma->rx.buf + rd;
- eff = slot[0] & GRCAN_MSG_IDE;
- rtr = slot[0] & GRCAN_MSG_RTR;
- if (eff) {
- cf->can_id = ((slot[0] & GRCAN_MSG_EID)
- >> GRCAN_MSG_EID_BIT);
- cf->can_id |= CAN_EFF_FLAG;
- } else {
- cf->can_id = ((slot[0] & GRCAN_MSG_BID)
- >> GRCAN_MSG_BID_BIT);
- }
- cf->len = can_cc_dlc2len((slot[1] & GRCAN_MSG_DLC)
- >> GRCAN_MSG_DLC_BIT);
- if (rtr) {
- cf->can_id |= CAN_RTR_FLAG;
- } else {
- if (cf->can_dlc > 0) {
- *(u32 *)(cf->data) = slot[2];
- if (cf->can_dlc > 4)
- *(u32 *)(cf->data + 4) = slot[3];
+ dlc = (slot[1] & GRCAN_MSG_DLC) >> GRCAN_MSG_DLC_BIT;
+ if (CHECK_SLOT_FDF(slot[1]))
+ cf->len = can_fd_dlc2len(dlc);
+ else
+ cf->len = can_cc_dlc2len(dlc);
+
+ bds = grcan_numbds(cf->len);
+ payload_offset = 0;
+ data = cf->data;
+
+ for (i = 0; i < bds; i++) {
+ slot = dma->rx.buf + rd;
+
+ if (i == 0) {
+ eff = slot[0] & GRCAN_MSG_IDE;
+ rtr = slot[0] & GRCAN_MSG_RTR;
+ if (eff) {
+ cf->can_id = ((slot[0] & GRCAN_MSG_EID)
+ >> GRCAN_MSG_EID_BIT);
+ cf->can_id |= CAN_EFF_FLAG;
+ } else {
+ cf->can_id = ((slot[0] & GRCAN_MSG_BID)
+ >> GRCAN_MSG_BID_BIT);
+ }
+ if (rtr)
+ cf->can_id |= CAN_RTR_FLAG;
+
+ dlc = (slot[1] & GRCAN_MSG_DLC) >> GRCAN_MSG_DLC_BIT;
+ if (CHECK_SLOT_FDF(slot[1]))
+ cf->len = can_fd_dlc2len(dlc);
+ else
+ cf->len = can_cc_dlc2len(dlc);
+
+ copy_len = min(cf->len, GRCAN_CLASSIC_DATA_SIZE);
+ memcpy(data, &slot[2], copy_len);
+ payload_offset += copy_len;
+ } else {
+ copy_len = min(cf->len - payload_offset, GRCAN_MSG_SIZE);
+ memcpy(data + payload_offset, slot, copy_len);
+ payload_offset += copy_len;
}
-
- stats->rx_bytes += cf->len;
+ rd += GRCAN_MSG_SIZE;
+ if (rd >= dma->tx.size)
+ rd -= dma->tx.size;
}
- stats->rx_packets++;
+ /* Update statistics and read pointer */
+ stats->rx_packets++;
+ stats->rx_bytes += cf->len;
netif_receive_skb(skb);
-
- rd = grcan_ring_add(rd, GRCAN_MSG_SIZE, dma->rx.size);
}
/* Make sure everything is read before allowing hardware to
@@ -1479,12 +1535,15 @@ static netdev_tx_t grcan_start_xmit(struct sk_buff *skb,
struct grcan_priv *priv = netdev_priv(dev);
struct grcan_registers __iomem *regs = priv->regs;
struct grcan_dma *dma = &priv->dma;
- struct can_frame *cf = (struct can_frame *)skb->data;
- u32 id, txwr, txrd, space, txctrl;
- int slotindex;
- u32 *slot;
- u32 rtr, eff, dlc, tmp, err;
+ struct can_frame *cf;
+ struct canfd_frame *cfd;
+ int i, bds, copy_len, payload_offset;
unsigned long flags;
+ u8 *payload;
+ u8 len;
+ u32 *slot;
+ u32 eff, rtr, dlc, tmp, err, can_id;
+ u32 id, txwr, txrd, space, txctrl;
u32 oneshotmode = priv->can.ctrlmode & CAN_CTRLMODE_ONE_SHOT;
if (can_dev_dropped_skb(dev, skb))
@@ -1496,6 +1555,20 @@ static netdev_tx_t grcan_start_xmit(struct sk_buff *skb,
if (priv->can.ctrlmode & CAN_CTRLMODE_LISTENONLY)
return NETDEV_TX_BUSY;
+ if (can_is_canfd_skb(skb)) {
+ cfd = (struct canfd_frame *)skb->data;
+ len = cfd->len;
+ dlc = can_fd_len2dlc(cfd->len);
+ can_id = cfd->can_id;
+ payload = cfd->data;
+ } else {
+ cf = (struct can_frame *)skb->data;
+ len = cf->len;
+ dlc = can_get_cc_dlc(cf, priv->can.ctrlmode);
+ can_id = cf->can_id;
+ payload = cf->data;
+ }
+
/* Reads of priv->eskbp and shut-downs of the queue needs to
* be atomic towards the updates to priv->eskbp and wake-ups
* of the queue in the interrupt handler.
@@ -1504,9 +1577,7 @@ static netdev_tx_t grcan_start_xmit(struct sk_buff *skb,
txwr = grcan_read_reg(®s->txwr);
space = grcan_txspace(dma->tx.size, txwr, priv->eskbp);
-
- slotindex = txwr / GRCAN_MSG_SIZE;
- slot = dma->tx.buf + txwr;
+ bds = grcan_numbds(len);
if (unlikely(space == 1))
netif_stop_queue(dev);
@@ -1522,24 +1593,38 @@ static netdev_tx_t grcan_start_xmit(struct sk_buff *skb,
return NETDEV_TX_BUSY;
}
- /* Convert and write CAN message to DMA buffer */
- eff = cf->can_id & CAN_EFF_FLAG;
- rtr = cf->can_id & CAN_RTR_FLAG;
- id = cf->can_id & (eff ? CAN_EFF_MASK : CAN_SFF_MASK);
- dlc = cf->len;
- if (eff)
- tmp = (id << GRCAN_MSG_EID_BIT) & GRCAN_MSG_EID;
- else
- tmp = (id << GRCAN_MSG_BID_BIT) & GRCAN_MSG_BID;
- slot[0] = (eff ? GRCAN_MSG_IDE : 0) | (rtr ? GRCAN_MSG_RTR : 0) | tmp;
-
- slot[1] = ((dlc << GRCAN_MSG_DLC_BIT) & GRCAN_MSG_DLC);
- slot[2] = 0;
- slot[3] = 0;
- if (dlc > 0) {
- slot[2] = *(u32 *)(cf->data); /* data aligned 64-bit */
- if (dlc > 4)
- slot[3] = *(u32 *)(cf->data + 4);
+ payload_offset = 0;
+ for (i = 0; i < bds; i++) {
+ slot = dma->tx.buf + txwr;
+ memset(slot, 0, GRCAN_MSG_SIZE);
+
+ if (i == 0) {
+ eff = can_id & CAN_EFF_FLAG;
+ rtr = can_id & CAN_RTR_FLAG;
+ id = can_id & (eff ? CAN_EFF_MASK : CAN_SFF_MASK);
+ if (eff)
+ tmp = (id << GRCAN_MSG_EID_BIT) & GRCAN_MSG_EID;
+ else
+ tmp = (id << GRCAN_MSG_BID_BIT) & GRCAN_MSG_BID;
+ slot[0] = (eff ? GRCAN_MSG_IDE : 0) | (rtr ? GRCAN_MSG_RTR : 0) | tmp;
+ slot[1] = ((dlc << GRCAN_MSG_DLC_BIT) & GRCAN_MSG_DLC);
+ if (can_is_canfd_skb(skb)) {
+ slot[1] |= GRCAN_TX_FDF;
+ if (cfd->flags & CANFD_BRS)
+ slot[1] |= GRCAN_TX_BRS;
+ }
+
+ copy_len = min(len, 8);
+ memcpy(&slot[2], payload, copy_len);
+ payload_offset += copy_len;
+ } else {
+ copy_len = min(len - payload_offset, GRCAN_MSG_SIZE);
+ memcpy(slot, payload + payload_offset, copy_len);
+ payload_offset += copy_len;
+ }
+ txwr += GRCAN_MSG_SIZE;
+ if (txwr >= dma->tx.size)
+ txwr -= dma->tx.size;
}
/* Checking that channel has not been disabled. These cases
@@ -1574,7 +1659,14 @@ static netdev_tx_t grcan_start_xmit(struct sk_buff *skb,
* can_put_echo_skb would be an error unless other measures are
* taken.
*/
- can_put_echo_skb(skb, dev, slotindex, 0);
+
+ can_put_echo_skb(skb, dev, priv->echo_skb_idx, 0);
+
+ /* Move to the next index in the echo skb buffer */
+ priv->echo_skb_idx = (priv->echo_skb_idx + 1) % priv->can.echo_skb_max;
+
+ if (priv->can.echo_skb[priv->echo_skb_idx])
+ netif_stop_queue(dev);
/* Make sure everything is written before allowing hardware to
* read from the memory
@@ -1582,8 +1674,7 @@ static netdev_tx_t grcan_start_xmit(struct sk_buff *skb,
wmb();
/* Update write pointer to start transmission */
- grcan_write_reg(®s->txwr,
- grcan_ring_add(txwr, GRCAN_MSG_SIZE, dma->tx.size));
+ grcan_write_reg(®s->txwr, txwr);
return NETDEV_TX_OK;
}
@@ -1734,12 +1825,15 @@ static int grcan_setup_netdev(struct platform_device *ofdev,
priv->ofdev_dev = &ofdev->dev;
priv->regs = base;
priv->can.bittiming_const = hwcap->bt_const;
+ priv->can.fd.data_bittiming_const = hwcap->bt_const;
priv->can.do_set_bittiming = hwcap->set_bittiming;
priv->can.do_set_mode = grcan_set_mode;
priv->can.do_get_berr_counter = grcan_get_berr_counter;
priv->can.clock.freq = ambafreq;
- priv->can.ctrlmode_supported =
- CAN_CTRLMODE_LISTENONLY | CAN_CTRLMODE_ONE_SHOT;
+ if (hwcap->fd)
+ priv->can.ctrlmode_supported = GRCAN_CTRL_MODES_FD;
+ else
+ priv->can.ctrlmode_supported = GRCAN_CTRL_MODES;
priv->need_txbug_workaround = txbug;
priv->hwcap = hwcap;
--
2.51.0
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