can: usb: PEAK-System Technik USB adapters driver core

This patch adds the core of the peak_usb driver which handles PEAK-System
Technik PCAN USB adapters. It defines the parts which are common to the
PCAN-USB adapters: can network interfaces management, network-to/from-usb
data path interface, timestamps management...

Tested-by: Oliver Hartkopp <[e-mail]>
Acked-by: Wolfgang Grandegger <[e-mail]>
Signed-off-by: Stephane Grosjean <[e-mail]>
Signed-off-by: Marc Kleine-Budde <[e-mail]>

drivers/net/can/usb/Kconfig

···
           This driver supports the CAN-USB/2 interface
           from esd electronic system design gmbh (http://www.esd.eu).
 
+config CAN_PEAK_USB
+	tristate "PEAK PCAN-USB/USB Pro interfaces"
+	---help---
+	  This driver supports the PCAN-USB and PCAN-USB Pro adapters
+	  from PEAK-System Technik (http://www.peak-system.com).
+
 endmenu

drivers/net/can/usb/Makefile

···
 
 obj-$(CONFIG_CAN_EMS_USB) += ems_usb.o
 obj-$(CONFIG_CAN_ESD_USB2) += esd_usb2.o
+obj-$(CONFIG_CAN_PEAK_USB) += peak_usb/
 
 ccflags-$(CONFIG_CAN_DEBUG_DEVICES) := -DDEBUG

drivers/net/can/usb/peak_usb/Makefile

···
+obj-$(CONFIG_CAN_PEAK_USB) += peak_usb.o
+peak_usb-y = pcan_usb_core.o

drivers/net/can/usb/peak_usb/pcan_usb_core.c

···
+/*
+ * CAN driver for PEAK System USB adapters
+ * Derived from the PCAN project file driver/src/pcan_usb_core.c
+ *
+ * Copyright (C) 2003-2010 PEAK System-Technik GmbH
+ * Copyright (C) 2010-2012 Stephane Grosjean <[e-mail]>
+ *
+ * Many thanks to Klaus Hitschler <[e-mail]>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published
+ * by the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+#include <linux/init.h>
+#include <linux/signal.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/netdevice.h>
+#include <linux/usb.h>
+
+#include <linux/can.h>
+#include <linux/can/dev.h>
+#include <linux/can/error.h>
+
+#include "pcan_usb_core.h"
+
+MODULE_AUTHOR("Stephane Grosjean <[e-mail]>");
+MODULE_DESCRIPTION("CAN driver for PEAK-System USB adapters");
+MODULE_LICENSE("GPL v2");
+
+/* Table of devices that work with this driver */
+static struct usb_device_id peak_usb_table[] = {
+	{USB_DEVICE(PCAN_USB_VENDOR_ID, PCAN_USB_PRODUCT_ID)},
+	{USB_DEVICE(PCAN_USB_VENDOR_ID, PCAN_USBPRO_PRODUCT_ID)},
+	{} /* Terminating entry */
+};
+
+MODULE_DEVICE_TABLE(usb, peak_usb_table);
+
+/* List of supported PCAN-USB adapters (NULL terminated list) */
+static struct peak_usb_adapter *peak_usb_adapters_list[] = {
+	&pcan_usb,
+	&pcan_usb_pro,
+	NULL,
+};
+
+/*
+ * dump memory
+ */
+#define DUMP_WIDTH	16
+void dump_mem(char *prompt, void *p, int l)
+{
+	pr_info("%s dumping %s (%d bytes):\n",
+		PCAN_USB_DRIVER_NAME, prompt ? prompt : "memory", l);
+	print_hex_dump(KERN_INFO, PCAN_USB_DRIVER_NAME " ", DUMP_PREFIX_NONE,
+		       DUMP_WIDTH, 1, p, l, false);
+}
+
+/*
+ * initialize a time_ref object with usb adapter own settings
+ */
+void peak_usb_init_time_ref(struct peak_time_ref *time_ref,
+			    struct peak_usb_adapter *adapter)
+{
+	if (time_ref) {
+		memset(time_ref, 0, sizeof(struct peak_time_ref));
+		time_ref->adapter = adapter;
+	}
+}
+
+static void peak_usb_add_us(struct timeval *tv, u32 delta_us)
+{
+	/* number of s. to add to final time */
+	u32 delta_s = delta_us / 1000000;
+
+	delta_us -= delta_s * 1000000;
+
+	tv->tv_usec += delta_us;
+	if (tv->tv_usec >= 1000000) {
+		tv->tv_usec -= 1000000;
+		delta_s++;
+	}
+	tv->tv_sec += delta_s;
+}
+
+/*
+ * sometimes, another now may be  more recent than current one...
+ */
+void peak_usb_update_ts_now(struct peak_time_ref *time_ref, u32 ts_now)
+{
+	time_ref->ts_dev_2 = ts_now;
+
+	/* should wait at least two passes before computing */
+	if (time_ref->tv_host.tv_sec > 0) {
+		u32 delta_ts = time_ref->ts_dev_2 - time_ref->ts_dev_1;
+
+		if (time_ref->ts_dev_2 < time_ref->ts_dev_1)
+			delta_ts &= (1 << time_ref->adapter->ts_used_bits) - 1;
+
+		time_ref->ts_total += delta_ts;
+	}
+}
+
+/*
+ * register device timestamp as now
+ */
+void peak_usb_set_ts_now(struct peak_time_ref *time_ref, u32 ts_now)
+{
+	if (time_ref->tv_host_0.tv_sec == 0) {
+		/* use monotonic clock to correctly compute further deltas */
+		time_ref->tv_host_0 = ktime_to_timeval(ktime_get());
+		time_ref->tv_host.tv_sec = 0;
+	} else {
+		/*
+		 * delta_us should not be >= 2^32 => delta_s should be < 4294
+		 * handle 32-bits wrapping here: if count of s. reaches 4200,
+		 * reset counters and change time base
+		 */
+		if (time_ref->tv_host.tv_sec != 0) {
+			u32 delta_s = time_ref->tv_host.tv_sec
+						- time_ref->tv_host_0.tv_sec;
+			if (delta_s > 4200) {
+				time_ref->tv_host_0 = time_ref->tv_host;
+				time_ref->ts_total = 0;
+			}
+		}
+
+		time_ref->tv_host = ktime_to_timeval(ktime_get());
+		time_ref->tick_count++;
+	}
+
+	time_ref->ts_dev_1 = time_ref->ts_dev_2;
+	peak_usb_update_ts_now(time_ref, ts_now);
+}
+
+/*
+ * compute timeval according to current ts and time_ref data
+ */
+void peak_usb_get_ts_tv(struct peak_time_ref *time_ref, u32 ts,
+			struct timeval *tv)
+{
+	/* protect from getting timeval before setting now */
+	if (time_ref->tv_host.tv_sec > 0) {
+		u64 delta_us;
+
+		delta_us = ts - time_ref->ts_dev_2;
+		if (ts < time_ref->ts_dev_2)
+			delta_us &= (1 << time_ref->adapter->ts_used_bits) - 1;
+
+		delta_us += time_ref->ts_total;
+
+		delta_us *= time_ref->adapter->us_per_ts_scale;
+		delta_us >>= time_ref->adapter->us_per_ts_shift;
+
+		*tv = time_ref->tv_host_0;
+		peak_usb_add_us(tv, (u32)delta_us);
+	} else {
+		*tv = ktime_to_timeval(ktime_get());
+	}
+}
+
+/*
+ * callback for bulk Rx urb
+ */
+static void peak_usb_read_bulk_callback(struct urb *urb)
+{
+	struct peak_usb_device *dev = urb->context;
+	struct net_device *netdev;
+	int err;
+
+	netdev = dev->netdev;
+
+	if (!netif_device_present(netdev))
+		return;
+
+	/* check reception status */
+	switch (urb->status) {
+	case 0:
+		/* success */
+		break;
+
+	case -EILSEQ:
+	case -ENOENT:
+	case -ECONNRESET:
+	case -ESHUTDOWN:
+		return;
+
+	default:
+		if (net_ratelimit())
+			netdev_err(netdev,
+				   "Rx urb aborted (%d)\n", urb->status);
+		goto resubmit_urb;
+	}
+
+	/* protect from any incoming empty msgs */
+	if ((urb->actual_length > 0) && (dev->adapter->dev_decode_buf)) {
+		/* handle these kinds of msgs only if _start callback called */
+		if (dev->state & PCAN_USB_STATE_STARTED) {
+			err = dev->adapter->dev_decode_buf(dev, urb);
+			if (err)
+				dump_mem("received usb message",
+					urb->transfer_buffer,
+					urb->transfer_buffer_length);
+		}
+	}
+
+resubmit_urb:
+	usb_fill_bulk_urb(urb, dev->udev,
+		usb_rcvbulkpipe(dev->udev, dev->ep_msg_in),
+		urb->transfer_buffer, dev->adapter->rx_buffer_size,
+		peak_usb_read_bulk_callback, dev);
+
+	usb_anchor_urb(urb, &dev->rx_submitted);
+	err = usb_submit_urb(urb, GFP_ATOMIC);
+	if (!err)
+		return;
+
+	usb_unanchor_urb(urb);
+
+	if (err == -ENODEV)
+		netif_device_detach(netdev);
+	else
+		netdev_err(netdev, "failed resubmitting read bulk urb: %d\n",
+			   err);
+}
+
+/*
+ * callback for bulk Tx urb
+ */
+static void peak_usb_write_bulk_callback(struct urb *urb)
+{
+	struct peak_tx_urb_context *context = urb->context;
+	struct peak_usb_device *dev;
+	struct net_device *netdev;
+
+	BUG_ON(!context);
+
+	dev = context->dev;
+	netdev = dev->netdev;
+
+	atomic_dec(&dev->active_tx_urbs);
+
+	if (!netif_device_present(netdev))
+		return;
+
+	/* check tx status */
+	switch (urb->status) {
+	case 0:
+		/* transmission complete */
+		netdev->stats.tx_packets++;
+		netdev->stats.tx_bytes += context->dlc;
+
+		/* prevent tx timeout */
+		netdev->trans_start = jiffies;
+		break;
+
+	default:
+		if (net_ratelimit())
+			netdev_err(netdev, "Tx urb aborted (%d)\n",
+				   urb->status);
+	case -EPROTO:
+	case -ENOENT:
+	case -ECONNRESET:
+	case -ESHUTDOWN:
+
+		break;
+	}
+
+	/* should always release echo skb and corresponding context */
+	can_get_echo_skb(netdev, context->echo_index);
+	context->echo_index = PCAN_USB_MAX_TX_URBS;
+
+	/* do wakeup tx queue in case of success only */
+	if (!urb->status)
+		netif_wake_queue(netdev);
+}
+
+/*
+ * called by netdev to send one skb on the CAN interface.
+ */
+static netdev_tx_t peak_usb_ndo_start_xmit(struct sk_buff *skb,
+					   struct net_device *netdev)
+{
+	struct peak_usb_device *dev = netdev_priv(netdev);
+	struct peak_tx_urb_context *context = NULL;
+	struct net_device_stats *stats = &netdev->stats;
+	struct can_frame *cf = (struct can_frame *)skb->data;
+	struct urb *urb;
+	u8 *obuf;
+	int i, err;
+	size_t size = dev->adapter->tx_buffer_size;
+
+	if (can_dropped_invalid_skb(netdev, skb))
+		return NETDEV_TX_OK;
+
+	for (i = 0; i < PCAN_USB_MAX_TX_URBS; i++)
+		if (dev->tx_contexts[i].echo_index == PCAN_USB_MAX_TX_URBS) {
+			context = dev->tx_contexts + i;
+			break;
+		}
+
+	if (!context) {
+		/* should not occur except during restart */
+		return NETDEV_TX_BUSY;
+	}
+
+	urb = context->urb;
+	obuf = urb->transfer_buffer;
+
+	err = dev->adapter->dev_encode_msg(dev, skb, obuf, &size);
+	if (err) {
+		if (net_ratelimit())
+			netdev_err(netdev, "packet dropped\n");
+		dev_kfree_skb(skb);
+		stats->tx_dropped++;
+		return NETDEV_TX_OK;
+	}
+
+	context->echo_index = i;
+	context->dlc = cf->can_dlc;
+
+	usb_anchor_urb(urb, &dev->tx_submitted);
+
+	can_put_echo_skb(skb, netdev, context->echo_index);
+
+	atomic_inc(&dev->active_tx_urbs);
+
+	err = usb_submit_urb(urb, GFP_ATOMIC);
+	if (err) {
+		can_free_echo_skb(netdev, context->echo_index);
+
+		usb_unanchor_urb(urb);
+
+		/* this context is not used in fact */
+		context->echo_index = PCAN_USB_MAX_TX_URBS;
+
+		atomic_dec(&dev->active_tx_urbs);
+
+		switch (err) {
+		case -ENODEV:
+			netif_device_detach(netdev);
+			break;
+		default:
+			netdev_warn(netdev, "tx urb submitting failed err=%d\n",
+				    err);
+		case -ENOENT:
+			/* cable unplugged */
+			stats->tx_dropped++;
+		}
+	} else {
+		netdev->trans_start = jiffies;
+
+		/* slow down tx path */
+		if (atomic_read(&dev->active_tx_urbs) >= PCAN_USB_MAX_TX_URBS)
+			netif_stop_queue(netdev);
+	}
+
+	return NETDEV_TX_OK;
+}
+
+/*
+ * start the CAN interface.
+ * Rx and Tx urbs are allocated here. Rx urbs are submitted here.
+ */
+static int peak_usb_start(struct peak_usb_device *dev)
+{
+	struct net_device *netdev = dev->netdev;
+	int err, i;
+
+	for (i = 0; i < PCAN_USB_MAX_RX_URBS; i++) {
+		struct urb *urb;
+		u8 *buf;
+
+		/* create a URB, and a buffer for it, to receive usb messages */
+		urb = usb_alloc_urb(0, GFP_KERNEL);
+		if (!urb) {
+			netdev_err(netdev, "No memory left for URBs\n");
+			err = -ENOMEM;
+			break;
+		}
+
+		buf = kmalloc(dev->adapter->rx_buffer_size, GFP_KERNEL);
+		if (!buf) {
+			netdev_err(netdev, "No memory left for USB buffer\n");
+			usb_free_urb(urb);
+			err = -ENOMEM;
+			break;
+		}
+
+		usb_fill_bulk_urb(urb, dev->udev,
+			usb_rcvbulkpipe(dev->udev, dev->ep_msg_in),
+			buf, dev->adapter->rx_buffer_size,
+			peak_usb_read_bulk_callback, dev);
+
+		/* ask last usb_free_urb() to also kfree() transfer_buffer */
+		urb->transfer_flags |= URB_FREE_BUFFER;
+		usb_anchor_urb(urb, &dev->rx_submitted);
+
+		err = usb_submit_urb(urb, GFP_KERNEL);
+		if (err) {
+			if (err == -ENODEV)
+				netif_device_detach(dev->netdev);
+
+			usb_unanchor_urb(urb);
+			kfree(buf);
+			usb_free_urb(urb);
+			break;
+		}
+
+		/* drop reference, USB core will take care of freeing it */
+		usb_free_urb(urb);
+	}
+
+	/* did we submit any URBs? Warn if we was not able to submit all urbs */
+	if (i < PCAN_USB_MAX_RX_URBS) {
+		if (i == 0) {
+			netdev_err(netdev, "couldn't setup any rx URB\n");
+			return err;
+		}
+
+		netdev_warn(netdev, "rx performance may be slow\n");
+	}
+
+	/* pre-alloc tx buffers and corresponding urbs */
+	for (i = 0; i < PCAN_USB_MAX_TX_URBS; i++) {
+		struct peak_tx_urb_context *context;
+		struct urb *urb;
+		u8 *buf;
+
+		/* create a URB and a buffer for it, to transmit usb messages */
+		urb = usb_alloc_urb(0, GFP_KERNEL);
+		if (!urb) {
+			netdev_err(netdev, "No memory left for URBs\n");
+			err = -ENOMEM;
+			break;
+		}
+
+		buf = kmalloc(dev->adapter->tx_buffer_size, GFP_KERNEL);
+		if (!buf) {
+			netdev_err(netdev, "No memory left for USB buffer\n");
+			usb_free_urb(urb);
+			err = -ENOMEM;
+			break;
+		}
+
+		context = dev->tx_contexts + i;
+		context->dev = dev;
+		context->urb = urb;
+
+		usb_fill_bulk_urb(urb, dev->udev,
+			usb_sndbulkpipe(dev->udev, dev->ep_msg_out),
+			buf, dev->adapter->tx_buffer_size,
+			peak_usb_write_bulk_callback, context);
+
+		/* ask last usb_free_urb() to also kfree() transfer_buffer */
+		urb->transfer_flags |= URB_FREE_BUFFER;
+	}
+
+	/* warn if we were not able to allocate enough tx contexts */
+	if (i < PCAN_USB_MAX_TX_URBS) {
+		if (i == 0) {
+			netdev_err(netdev, "couldn't setup any tx URB\n");
+			return err;
+		}
+
+		netdev_warn(netdev, "tx performance may be slow\n");
+	}
+
+	if (dev->adapter->dev_start) {
+		err = dev->adapter->dev_start(dev);
+		if (err)
+			goto failed;
+	}
+
+	dev->state |= PCAN_USB_STATE_STARTED;
+
+	/* can set bus on now */
+	if (dev->adapter->dev_set_bus) {
+		err = dev->adapter->dev_set_bus(dev, 1);
+		if (err)
+			goto failed;
+	}
+
+	dev->can.state = CAN_STATE_ERROR_ACTIVE;
+
+	return 0;
+
+failed:
+	if (err == -ENODEV)
+		netif_device_detach(dev->netdev);
+
+	netdev_warn(netdev, "couldn't submit control: %d\n", err);
+
+	return err;
+}
+
+/*
+ * called by netdev to open the corresponding CAN interface.
+ */
+static int peak_usb_ndo_open(struct net_device *netdev)
+{
+	struct peak_usb_device *dev = netdev_priv(netdev);
+	int err;
+
+	/* common open */
+	err = open_candev(netdev);
+	if (err)
+		return err;
+
+	/* finally start device */
+	err = peak_usb_start(dev);
+	if (err) {
+		netdev_err(netdev, "couldn't start device: %d\n", err);
+		close_candev(netdev);
+		return err;
+	}
+
+	dev->open_time = jiffies;
+	netif_start_queue(netdev);
+
+	return 0;
+}
+
+/*
+ * unlink in-flight Rx and Tx urbs and free their memory.
+ */
+static void peak_usb_unlink_all_urbs(struct peak_usb_device *dev)
+{
+	int i;
+
+	/* free all Rx (submitted) urbs */
+	usb_kill_anchored_urbs(&dev->rx_submitted);
+
+	/* free unsubmitted Tx urbs first */
+	for (i = 0; i < PCAN_USB_MAX_TX_URBS; i++) {
+		struct urb *urb = dev->tx_contexts[i].urb;
+
+		if (!urb ||
+		    dev->tx_contexts[i].echo_index != PCAN_USB_MAX_TX_URBS) {
+			/*
+			 * this urb is already released or always submitted,
+			 * let usb core free by itself
+			 */
+			continue;
+		}
+
+		usb_free_urb(urb);
+		dev->tx_contexts[i].urb = NULL;
+	}
+
+	/* then free all submitted Tx urbs */
+	usb_kill_anchored_urbs(&dev->tx_submitted);
+	atomic_set(&dev->active_tx_urbs, 0);
+}
+
+/*
+ * called by netdev to close the corresponding CAN interface.
+ */
+static int peak_usb_ndo_stop(struct net_device *netdev)
+{
+	struct peak_usb_device *dev = netdev_priv(netdev);
+
+	dev->state &= ~PCAN_USB_STATE_STARTED;
+	netif_stop_queue(netdev);
+
+	/* unlink all pending urbs and free used memory */
+	peak_usb_unlink_all_urbs(dev);
+
+	if (dev->adapter->dev_stop)
+		dev->adapter->dev_stop(dev);
+
+	close_candev(netdev);
+
+	dev->open_time = 0;
+	dev->can.state = CAN_STATE_STOPPED;
+
+	/* can set bus off now */
+	if (dev->adapter->dev_set_bus) {
+		int err = dev->adapter->dev_set_bus(dev, 0);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
+/*
+ * handle end of waiting for the device to reset
+ */
+void peak_usb_restart_complete(struct peak_usb_device *dev)
+{
+	/* finally MUST update can state */
+	dev->can.state = CAN_STATE_ERROR_ACTIVE;
+
+	/* netdev queue can be awaken now */
+	netif_wake_queue(dev->netdev);
+}
+
+void peak_usb_async_complete(struct urb *urb)
+{
+	kfree(urb->transfer_buffer);
+	usb_free_urb(urb);
+}
+
+/*
+ * device (auto-)restart mechanism runs in a timer context =>
+ * MUST handle restart with asynchronous usb transfers
+ */
+static int peak_usb_restart(struct peak_usb_device *dev)
+{
+	struct urb *urb;
+	int err;
+	u8 *buf;
+
+	/*
+	 * if device doesn't define any asynchronous restart handler, simply
+	 * wake the netdev queue up
+	 */
+	if (!dev->adapter->dev_restart_async) {
+		peak_usb_restart_complete(dev);
+		return 0;
+	}
+
+	/* first allocate a urb to handle the asynchronous steps */
+	urb = usb_alloc_urb(0, GFP_ATOMIC);
+	if (!urb) {
+		netdev_err(dev->netdev, "no memory left for urb\n");
+		return -ENOMEM;
+	}
+
+	/* also allocate enough space for the commands to send */
+	buf = kmalloc(PCAN_USB_MAX_CMD_LEN, GFP_ATOMIC);
+	if (!buf) {
+		netdev_err(dev->netdev, "no memory left for async cmd\n");
+		usb_free_urb(urb);
+		return -ENOMEM;
+	}
+
+	/* call the device specific handler for the restart */
+	err = dev->adapter->dev_restart_async(dev, urb, buf);
+	if (!err)
+		return 0;
+
+	kfree(buf);
+	usb_free_urb(urb);
+
+	return err;
+}
+
+/*
+ * candev callback used to change CAN mode.
+ * Warning: this is called from a timer context!
+ */
+static int peak_usb_set_mode(struct net_device *netdev, enum can_mode mode)
+{
+	struct peak_usb_device *dev = netdev_priv(netdev);
+	int err = 0;
+
+	if (!dev->open_time)
+		return -EINVAL;
+
+	switch (mode) {
+	case CAN_MODE_START:
+		err = peak_usb_restart(dev);
+		if (err)
+			netdev_err(netdev, "couldn't start device (err %d)\n",
+				   err);
+		break;
+
+	default:
+		return -EOPNOTSUPP;
+	}
+
+	return err;
+}
+
+/*
+ * candev callback used to set device bitrate.
+ */
+static int peak_usb_set_bittiming(struct net_device *netdev)
+{
+	struct peak_usb_device *dev = netdev_priv(netdev);
+	struct can_bittiming *bt = &dev->can.bittiming;
+
+	if (dev->adapter->dev_set_bittiming) {
+		int err = dev->adapter->dev_set_bittiming(dev, bt);
+
+		if (err)
+			netdev_info(netdev, "couldn't set bitrate (err %d)\n",
+				err);
+		return err;
+	}
+
+	return 0;
+}
+
+static const struct net_device_ops peak_usb_netdev_ops = {
+	.ndo_open = peak_usb_ndo_open,
+	.ndo_stop = peak_usb_ndo_stop,
+	.ndo_start_xmit = peak_usb_ndo_start_xmit,
+};
+
+/*
+ * create one device which is attached to CAN controller #ctrl_idx of the
+ * usb adapter.
+ */
+static int peak_usb_create_dev(struct peak_usb_adapter *peak_usb_adapter,
+			       struct usb_interface *intf, int ctrl_idx)
+{
+	struct usb_device *usb_dev = interface_to_usbdev(intf);
+	int sizeof_candev = peak_usb_adapter->sizeof_dev_private;
+	struct peak_usb_device *dev;
+	struct net_device *netdev;
+	int i, err;
+	u16 tmp16;
+
+	if (sizeof_candev < sizeof(struct peak_usb_device))
+		sizeof_candev = sizeof(struct peak_usb_device);
+
+	netdev = alloc_candev(sizeof_candev, PCAN_USB_MAX_TX_URBS);
+	if (!netdev) {
+		dev_err(&intf->dev, "%s: couldn't alloc candev\n",
+			PCAN_USB_DRIVER_NAME);
+		return -ENOMEM;
+	}
+
+	dev = netdev_priv(netdev);
+
+	/* allocate a buffer large enough to send commands */
+	dev->cmd_buf = kmalloc(PCAN_USB_MAX_CMD_LEN, GFP_KERNEL);
+	if (!dev->cmd_buf) {
+		dev_err(&intf->dev, "%s: couldn't alloc cmd buffer\n",
+			PCAN_USB_DRIVER_NAME);
+		err = -ENOMEM;
+		goto lbl_set_intf_data;
+	}
+
+	dev->udev = usb_dev;
+	dev->netdev = netdev;
+	dev->adapter = peak_usb_adapter;
+	dev->ctrl_idx = ctrl_idx;
+	dev->state = PCAN_USB_STATE_CONNECTED;
+
+	dev->ep_msg_in = peak_usb_adapter->ep_msg_in;
+	dev->ep_msg_out = peak_usb_adapter->ep_msg_out[ctrl_idx];
+
+	dev->can.clock = peak_usb_adapter->clock;
+	dev->can.bittiming_const = &peak_usb_adapter->bittiming_const;
+	dev->can.do_set_bittiming = peak_usb_set_bittiming;
+	dev->can.do_set_mode = peak_usb_set_mode;
+	dev->can.ctrlmode_supported = CAN_CTRLMODE_3_SAMPLES |
+				      CAN_CTRLMODE_LISTENONLY;
+
+	netdev->netdev_ops = &peak_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 < PCAN_USB_MAX_TX_URBS; i++)
+		dev->tx_contexts[i].echo_index = PCAN_USB_MAX_TX_URBS;
+
+	dev->prev_siblings = usb_get_intfdata(intf);
+	usb_set_intfdata(intf, dev);
+
+	SET_NETDEV_DEV(netdev, &intf->dev);
+
+	err = register_candev(netdev);
+	if (err) {
+		dev_err(&intf->dev, "couldn't register CAN device: %d\n", err);
+		goto lbl_free_cmd_buf;
+	}
+
+	if (dev->prev_siblings)
+		(dev->prev_siblings)->next_siblings = dev;
+
+	/* keep hw revision into the netdevice */
+	tmp16 = le16_to_cpu(usb_dev->descriptor.bcdDevice);
+	dev->device_rev = tmp16 >> 8;
+
+	if (dev->adapter->dev_init) {
+		err = dev->adapter->dev_init(dev);
+		if (err)
+			goto lbl_free_cmd_buf;
+	}
+
+	/* set bus off */
+	if (dev->adapter->dev_set_bus) {
+		err = dev->adapter->dev_set_bus(dev, 0);
+		if (err)
+			goto lbl_free_cmd_buf;
+	}
+
+	/* get device number early */
+	if (dev->adapter->dev_get_device_id)
+		dev->adapter->dev_get_device_id(dev, &dev->device_number);
+
+	netdev_info(netdev, "attached to %s channel %u (device %u)\n",
+			peak_usb_adapter->name, ctrl_idx, dev->device_number);
+
+	return 0;
+
+lbl_free_cmd_buf:
+	kfree(dev->cmd_buf);
+
+lbl_set_intf_data:
+	usb_set_intfdata(intf, dev->prev_siblings);
+	free_candev(netdev);
+
+	return err;
+}
+
+/*
+ * called by the usb core when the device is unplugged from the system
+ */
+static void peak_usb_disconnect(struct usb_interface *intf)
+{
+	struct peak_usb_device *dev;
+
+	/* unregister as many netdev devices as siblings */
+	for (dev = usb_get_intfdata(intf); dev; dev = dev->prev_siblings) {
+		struct net_device *netdev = dev->netdev;
+		char name[IFNAMSIZ];
+
+		dev->state &= ~PCAN_USB_STATE_CONNECTED;
+		strncpy(name, netdev->name, IFNAMSIZ);
+
+		unregister_netdev(netdev);
+		free_candev(netdev);
+
+		kfree(dev->cmd_buf);
+		dev->next_siblings = NULL;
+		if (dev->adapter->dev_free)
+			dev->adapter->dev_free(dev);
+
+		dev_info(&intf->dev, "%s removed\n", name);
+	}
+
+	usb_set_intfdata(intf, NULL);
+}
+
+/*
+ * probe function for new PEAK-System devices
+ */
+static int peak_usb_probe(struct usb_interface *intf,
+			  const struct usb_device_id *id)
+{
+	struct usb_device *usb_dev = interface_to_usbdev(intf);
+	struct peak_usb_adapter *peak_usb_adapter, **pp;
+	int i, err = -ENOMEM;
+
+	usb_dev = interface_to_usbdev(intf);
+
+	/* get corresponding PCAN-USB adapter */
+	for (pp = peak_usb_adapters_list; *pp; pp++)
+		if ((*pp)->device_id == usb_dev->descriptor.idProduct)
+			break;
+
+	peak_usb_adapter = *pp;
+	if (!peak_usb_adapter) {
+		/* should never come except device_id bad usage in this file */
+		pr_err("%s: didn't find device id. 0x%x in devices list\n",
+			PCAN_USB_DRIVER_NAME, usb_dev->descriptor.idProduct);
+		return -ENODEV;
+	}
+
+	/* got corresponding adapter: check if it handles current interface */
+	if (peak_usb_adapter->intf_probe) {
+		err = peak_usb_adapter->intf_probe(intf);
+		if (err)
+			return err;
+	}
+
+	for (i = 0; i < peak_usb_adapter->ctrl_count; i++) {
+		err = peak_usb_create_dev(peak_usb_adapter, intf, i);
+		if (err) {
+			/* deregister already created devices */
+			peak_usb_disconnect(intf);
+			break;
+		}
+	}
+
+	return err;
+}
+
+/* usb specific object needed to register this driver with the usb subsystem */
+static struct usb_driver peak_usb_driver = {
+	.name = PCAN_USB_DRIVER_NAME,
+	.disconnect = peak_usb_disconnect,
+	.probe = peak_usb_probe,
+	.id_table = peak_usb_table,
+};
+
+static int __init peak_usb_init(void)
+{
+	int err;
+
+	/* register this driver with the USB subsystem */
+	err = usb_register(&peak_usb_driver);
+	if (err)
+		pr_err("%s: usb_register failed (err %d)\n",
+			PCAN_USB_DRIVER_NAME, err);
+
+	return err;
+}
+
+static int peak_usb_do_device_exit(struct device *d, void *arg)
+{
+	struct usb_interface *intf = to_usb_interface(d);
+	struct peak_usb_device *dev;
+
+	/* stop as many netdev devices as siblings */
+	for (dev = usb_get_intfdata(intf); dev; dev = dev->prev_siblings) {
+		struct net_device *netdev = dev->netdev;
+
+		if (netif_device_present(netdev))
+			if (dev->adapter->dev_exit)
+				dev->adapter->dev_exit(dev);
+	}
+
+	return 0;
+}
+
+static void __exit peak_usb_exit(void)
+{
+	int err;
+
+	/* last chance do send any synchronous commands here */
+	err = driver_for_each_device(&peak_usb_driver.drvwrap.driver, NULL,
+				     NULL, peak_usb_do_device_exit);
+	if (err)
+		pr_err("%s: failed to stop all can devices (err %d)\n",
+			PCAN_USB_DRIVER_NAME, err);
+
+	/* deregister this driver with the USB subsystem */
+	usb_deregister(&peak_usb_driver);
+
+	pr_info("%s: PCAN-USB interfaces driver unloaded\n",
+		PCAN_USB_DRIVER_NAME);
+}
+
+module_init(peak_usb_init);
+module_exit(peak_usb_exit);

drivers/net/can/usb/peak_usb/pcan_usb_core.h

···
+/*
+ * CAN driver for PEAK System USB adapters
+ * Derived from the PCAN project file driver/src/pcan_usb_core.c
+ *
+ * Copyright (C) 2003-2010 PEAK System-Technik GmbH
+ * Copyright (C) 2010-2012 Stephane Grosjean <[e-mail]>
+ *
+ * Many thanks to Klaus Hitschler <[e-mail]>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published
+ * by the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+#ifndef PCAN_USB_CORE_H
+#define PCAN_USB_CORE_H
+
+/* PEAK-System vendor id. */
+#define PCAN_USB_VENDOR_ID		0x0c72
+
+/* supported device ids. */
+#define PCAN_USB_PRODUCT_ID		0x000c
+#define PCAN_USBPRO_PRODUCT_ID		0x000d
+
+#define PCAN_USB_DRIVER_NAME		"peak_usb"
+
+/* number of urbs that are submitted for rx/tx per channel */
+#define PCAN_USB_MAX_RX_URBS		4
+#define PCAN_USB_MAX_TX_URBS		10
+
+/* usb adapters maximum channels per usb interface */
+#define PCAN_USB_MAX_CHANNEL		2
+
+/* maximum length of the usb commands sent to/received from  the devices */
+#define PCAN_USB_MAX_CMD_LEN		32
+
+struct peak_usb_device;
+
+/* PEAK-System USB adapter descriptor */
+struct peak_usb_adapter {
+	char *name;
+	u32 device_id;
+	struct can_clock clock;
+	struct can_bittiming_const bittiming_const;
+	unsigned int ctrl_count;
+
+	int (*intf_probe)(struct usb_interface *intf);
+
+	int (*dev_init)(struct peak_usb_device *dev);
+	void (*dev_exit)(struct peak_usb_device *dev);
+	void (*dev_free)(struct peak_usb_device *dev);
+	int (*dev_open)(struct peak_usb_device *dev);
+	int (*dev_close)(struct peak_usb_device *dev);
+	int (*dev_set_bittiming)(struct peak_usb_device *dev,
+					struct can_bittiming *bt);
+	int (*dev_set_bus)(struct peak_usb_device *dev, u8 onoff);
+	int (*dev_get_device_id)(struct peak_usb_device *dev, u32 *device_id);
+	int (*dev_decode_buf)(struct peak_usb_device *dev, struct urb *urb);
+	int (*dev_encode_msg)(struct peak_usb_device *dev, struct sk_buff *skb,
+					u8 *obuf, size_t *size);
+	int (*dev_start)(struct peak_usb_device *dev);
+	int (*dev_stop)(struct peak_usb_device *dev);
+	int (*dev_restart_async)(struct peak_usb_device *dev, struct urb *urb,
+					u8 *buf);
+	u8 ep_msg_in;
+	u8 ep_msg_out[PCAN_USB_MAX_CHANNEL];
+	u8 ts_used_bits;
+	u32 ts_period;
+	u8 us_per_ts_shift;
+	u32 us_per_ts_scale;
+
+	int rx_buffer_size;
+	int tx_buffer_size;
+	int sizeof_dev_private;
+};
+
+extern struct peak_usb_adapter pcan_usb;
+extern struct peak_usb_adapter pcan_usb_pro;
+
+struct peak_time_ref {
+	struct timeval tv_host_0, tv_host;
+	u32 ts_dev_1, ts_dev_2;
+	u64 ts_total;
+	u32 tick_count;
+	struct peak_usb_adapter *adapter;
+};
+
+struct peak_tx_urb_context {
+	struct peak_usb_device *dev;
+	u32 echo_index;
+	u8 dlc;
+	struct urb *urb;
+};
+
+#define PCAN_USB_STATE_CONNECTED	0x00000001
+#define PCAN_USB_STATE_STARTED		0x00000002
+
+/* PEAK-System USB device */
+struct peak_usb_device {
+	struct can_priv can;
+	struct peak_usb_adapter *adapter;
+	unsigned int ctrl_idx;
+	int open_time;
+	u32 state;
+
+	struct sk_buff *echo_skb[PCAN_USB_MAX_TX_URBS];
+
+	struct usb_device *udev;
+	struct net_device *netdev;
+
+	atomic_t active_tx_urbs;
+	struct usb_anchor tx_submitted;
+	struct peak_tx_urb_context tx_contexts[PCAN_USB_MAX_TX_URBS];
+
+	u8 *cmd_buf;
+	struct usb_anchor rx_submitted;
+
+	u32 device_number;
+	u8 device_rev;
+
+	u8 ep_msg_in;
+	u8 ep_msg_out;
+
+	u16 bus_load;
+
+	struct peak_usb_device *prev_siblings;
+	struct peak_usb_device *next_siblings;
+};
+
+void dump_mem(char *prompt, void *p, int l);
+
+/* common timestamp management */
+void peak_usb_init_time_ref(struct peak_time_ref *time_ref,
+			    struct peak_usb_adapter *adapter);
+void peak_usb_update_ts_now(struct peak_time_ref *time_ref, u32 ts_now);
+void peak_usb_set_ts_now(struct peak_time_ref *time_ref, u32 ts_now);
+void peak_usb_get_ts_tv(struct peak_time_ref *time_ref, u32 ts,
+			struct timeval *tv);
+
+void peak_usb_async_complete(struct urb *urb);
+void peak_usb_restart_complete(struct peak_usb_device *dev);
+#endif