Re: [PATCH 2/2] ems_usb: Added support for EMS CPC-USB/ARM7 CAN/USB interface

Hi Sebastian,

Sebastian Haas wrote:

This patch adds support for one channel CAN/USB interace CPC-USB/ARM7 from
EMS Dr. Thomas Wuensche (http://www.ems-wuensche.com).

Signed-off-by: Sebastian Haas <redacted>

The driver is almost OK from the Socket-CAN point of view. Just some
*final* nitpicking:

[snip]

+static void ems_usb_read_interrupt_callback(struct urb *urb)
+{
+	struct ems_usb *dev = urb->context;
+	struct net_device *netdev;
+	int err;
+
+	netdev = dev->netdev;

Could be done in the declaration part above.

+	if (!netif_device_present(netdev))
+		return;
+
+	switch (urb->status) {
+	case 0:
+		dev->free_slots = dev->intr_in_buffer[1];
+		break;
+
+	case -ECONNRESET: /* unlink */
+	case -ENOENT:
+	case -ESHUTDOWN:
+		return;
+
+	default:
+		dev_info(netdev->dev.parent, "Rx interrupt aborted %d\n",
+			 urb->status);
+		break;
+	}
+
+	err = usb_submit_urb(urb, GFP_ATOMIC);
+
+	if (err == -ENODEV)
+		netif_device_detach(netdev);
+	else if (err)
+		dev_err(netdev->dev.parent,
+			"failed resubmitting intr urb: %d\n", err);
+
+	return;
+}
+
+static void ems_usb_rx_can_msg(struct ems_usb *dev, struct ems_cpc_msg *msg)
+{
+	struct can_frame *cf;
+	struct sk_buff *skb;
+	int i;
+	struct net_device_stats *stats = &dev->netdev->stats;
+
+	skb = dev_alloc_skb(sizeof(struct can_frame));

Please use netdev_alloc_skb() ...

+	if (skb == NULL)
+		return;
+
+	skb->dev = dev->netdev;

... making the line above obsolete.

+	skb->protocol = htons(ETH_P_CAN);
+
+	cf = (struct can_frame *)skb_put(skb, sizeof(struct can_frame));
+
+	cf->can_id = msg->msg.can_msg.id;
+	cf->can_dlc = min_t(u8, msg->msg.can_msg.length, 8);
+
+	if (msg->type == CPC_MSG_TYPE_EXT_CAN_FRAME
+	    || msg->type == CPC_MSG_TYPE_EXT_RTR_FRAME)
+		cf->can_id |= CAN_EFF_FLAG;
+
+	if (msg->type == CPC_MSG_TYPE_RTR_FRAME
+	    || msg->type == CPC_MSG_TYPE_EXT_RTR_FRAME) {
+		cf->can_id |= CAN_RTR_FLAG;
+	} else {
+		for (i = 0; i < cf->can_dlc; i++)
+			cf->data[i] = msg->msg.can_msg.msg[i];
+	}
+
+	netif_rx(skb);
+
+	dev->netdev->last_rx = jiffies;
+	stats->rx_packets++;
+	stats->rx_bytes += cf->can_dlc;
+}
+
+static void ems_usb_rx_err(struct ems_usb *dev, struct ems_cpc_msg *msg)
+{
+	struct can_frame *cf;
+	struct sk_buff *skb;
+	struct net_device_stats *stats = &dev->netdev->stats;
+
+	skb = dev_alloc_skb(sizeof(struct can_frame));
+	if (skb == NULL)
+		return;
+
+	skb->dev = dev->netdev;

Ditto.

[snip]

+static int ems_usb_start_xmit(struct sk_buff *skb, struct net_device *netdev)
+{
+	struct ems_usb *dev = netdev_priv(netdev);
+	struct ems_tx_urb_context *context = NULL;
+	struct net_device_stats *stats = &netdev->stats;
+	struct can_frame *cf = (struct can_frame *)skb->data;
+	struct ems_cpc_msg *msg;
+	struct urb *urb;
+	u8 *buf;
+	int i, err;
+	size_t size = CPC_HEADER_SIZE + CPC_MSG_HEADER_LEN
+			+ sizeof(struct cpc_can_msg);
+
+	/* create a URB, and a buffer for it, and copy the data to the URB */
+	urb = usb_alloc_urb(0, GFP_ATOMIC);
+	if (!urb) {
+		dev_err(netdev->dev.parent, "No memory left for URBs\n");
+		goto nomem;
+	}
+
+	buf = usb_buffer_alloc(dev->udev, size, GFP_ATOMIC, &urb->transfer_dma);
+	if (!buf) {
+		dev_err(netdev->dev.parent, "No memory left for USB buffer\n");
+		usb_free_urb(urb);
+		goto nomem;
+	}
+
+	msg = (struct ems_cpc_msg *)&buf[CPC_HEADER_SIZE];
+
+	msg->msg.can_msg.id = cf->can_id & 0x1FFFFFFFU;

Please use CAN_ERR_MASK instead (even if the name is somehow
misleading). See http://lxr.linux.no/#linux+v2.6.31/include/linux/can.h#L31.

[snip]

+}
+
+

Remove one empty line, please.

+static void init_params_sja1000(struct ems_cpc_msg *msg)
+{
+	struct cpc_sja1000_params *sja1000 =
+		&msg->msg.can_params.cc_params.sja1000;
+
+	msg->type = CPC_CMD_TYPE_CAN_PARAMS;
+	msg->length = sizeof(struct cpc_can_params);
+	msg->msgid = 0;
+
+	msg->msg.can_params.cc_type = CPC_CC_TYPE_SJA1000;
+
+	/* Acceptance filter open */
+	sja1000->acc_code0 = 0x00;
+	sja1000->acc_code1 = 0x00;
+	sja1000->acc_code2 = 0x00;
+	sja1000->acc_code3 = 0x00;
+
+	/* Acceptance filter open */
+	sja1000->acc_mask0 = 0xFF;
+	sja1000->acc_mask1 = 0xFF;
+	sja1000->acc_mask2 = 0xFF;
+	sja1000->acc_mask3 = 0xFF;
+
+	sja1000->btr0 = 0;
+	sja1000->btr1 = 0;
+
+	sja1000->outp_contr = SJA1000_DEFAULT_OUTPUT_CONTROL;
+	sja1000->mode = SJA1000_MOD_RM;
+}
+
+/*
+ * probe function for new CPC-USB devices
+ */
+static int ems_usb_probe(struct usb_interface *intf,
+			 const struct usb_device_id *id)
+{
+	struct net_device *netdev;
+	struct ems_usb *dev;
+	int i, err;
+
+	netdev = alloc_candev(sizeof(struct ems_usb));
+	if (!netdev) {
+		dev_err(netdev->dev.parent, "Couldn't alloc candev\n");
+		return -ENOMEM;
+	}
+
+	dev = netdev_priv(netdev);
+
+	dev->udev = interface_to_usbdev(intf);
+	dev->netdev = netdev;
+
+	dev->can.state = CAN_STATE_STOPPED;
+	dev->can.bittiming_const = &ems_usb_bittiming_const;
+	dev->can.do_set_bittiming = ems_usb_set_bittiming;
+	dev->can.do_set_mode = ems_usb_set_mode;
+
+	netdev->flags |= IFF_ECHO; /* we support local echo */
+
+	/*
+	 * The device actually uses a 16MHz clock to generate the CAN clock
+	 * but it expects SJA1000 bit settings based on 8MHz (is internally
+	 * converted).
+	 */

Should go up to the macro definition.

+	dev->can.clock.freq = EMS_USB_ARM7_CLOCK;
+
+	netdev->netdev_ops = &ems_usb_netdev_ops;
+
+	netdev->flags |= IFF_ECHO; /* we support local echo */
+
+	init_usb_anchor(&dev->rx_submitted);
+
+	init_usb_anchor(&dev->tx_submitted);
+	atomic_set(&dev->active_tx_urbs, 0);
+
+	for (i = 0; i < MAX_TX_URBS; i++)
+		dev->tx_contexts[i].echo_index = MAX_TX_URBS;
+
+	dev->intr_urb = usb_alloc_urb(0, GFP_KERNEL);
+	if (!dev->intr_urb) {
+		dev_err(netdev->dev.parent, "Couldn't alloc intr URB\n");
+		free_candev(netdev);

Please use goto's for cleanup to avoid code duplication.

+		return -ENOMEM;
+	}
+
+	dev->intr_in_buffer = kzalloc(INTR_IN_BUFFER_SIZE, GFP_KERNEL);
+	if (!dev->intr_in_buffer) {
+		dev_err(netdev->dev.parent, "Couldn't alloc Intr buffer\n");
+		free_candev(netdev);
+		usb_free_urb(dev->intr_urb);
+		return -ENOMEM;

Ditto.

+	}
+
+	dev->tx_msg_buffer = kzalloc(CPC_HEADER_SIZE +
+				     sizeof(struct ems_cpc_msg), GFP_KERNEL);
+	if (!dev->tx_msg_buffer) {
+		dev_err(netdev->dev.parent, "Couldn't alloc Tx buffer\n");
+		free_candev(netdev);
+		usb_free_urb(dev->intr_urb);
+		kfree(dev->intr_in_buffer);
+		return -ENOMEM;

Ditto.

+	}
+
+	usb_set_intfdata(intf, dev);
+
+	SET_NETDEV_DEV(netdev, &intf->dev);
+
+	init_params_sja1000(&dev->active_params);
+
+	err = ems_usb_command_msg(dev, &dev->active_params);
+	if (err) {
+		dev_err(netdev->dev.parent,
+			"couldn't initialize controller: %d\n", err);
+		free_candev(netdev);
+		usb_free_urb(dev->intr_urb);
+		return err;

Ditto. Also kfree(dev->intr_in_buffer) seems to be missing.

Please add a version number to the next patch, e.g. [PATCH v3 ...].

It would also be nice, if some USB guru's could have a look as well.

Thanks,

Wolfgang.
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