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// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2025 Vincent Mailhol <mailhol@kernel.org> */
#include <linux/array_size.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/netdevice.h>
#include <linux/units.h>
#include <linux/string_choices.h>
#include <linux/can.h>
#include <linux/can/bittiming.h>
#include <linux/can/dev.h>
#include <linux/can/skb.h>
struct dummy_can {
struct can_priv can;
struct net_device *dev;
};
static struct dummy_can *dummy_can;
static const struct can_bittiming_const dummy_can_bittiming_const = {
.name = "dummy_can CC",
.tseg1_min = 2,
.tseg1_max = 256,
.tseg2_min = 2,
.tseg2_max = 128,
.sjw_max = 128,
.brp_min = 1,
.brp_max = 512,
.brp_inc = 1
};
static const struct can_bittiming_const dummy_can_fd_databittiming_const = {
.name = "dummy_can FD",
.tseg1_min = 2,
.tseg1_max = 256,
.tseg2_min = 2,
.tseg2_max = 128,
.sjw_max = 128,
.brp_min = 1,
.brp_max = 512,
.brp_inc = 1
};
static const struct can_tdc_const dummy_can_fd_tdc_const = {
.tdcv_min = 0,
.tdcv_max = 0, /* Manual mode not supported. */
.tdco_min = 0,
.tdco_max = 127,
.tdcf_min = 0,
.tdcf_max = 127
};
static const struct can_bittiming_const dummy_can_xl_databittiming_const = {
.name = "dummy_can XL",
.tseg1_min = 2,
.tseg1_max = 256,
.tseg2_min = 2,
.tseg2_max = 128,
.sjw_max = 128,
.brp_min = 1,
.brp_max = 512,
.brp_inc = 1
};
static const struct can_tdc_const dummy_can_xl_tdc_const = {
.tdcv_min = 0,
.tdcv_max = 0, /* Manual mode not supported. */
.tdco_min = 0,
.tdco_max = 127,
.tdcf_min = 0,
.tdcf_max = 127
};
static const struct can_pwm_const dummy_can_pwm_const = {
.pwms_min = 1,
.pwms_max = 8,
.pwml_min = 2,
.pwml_max = 24,
.pwmo_min = 0,
.pwmo_max = 16,
};
static void dummy_can_print_bittiming(struct net_device *dev,
struct can_bittiming *bt)
{
netdev_dbg(dev, "\tbitrate: %u\n", bt->bitrate);
netdev_dbg(dev, "\tsample_point: %u\n", bt->sample_point);
netdev_dbg(dev, "\ttq: %u\n", bt->tq);
netdev_dbg(dev, "\tprop_seg: %u\n", bt->prop_seg);
netdev_dbg(dev, "\tphase_seg1: %u\n", bt->phase_seg1);
netdev_dbg(dev, "\tphase_seg2: %u\n", bt->phase_seg2);
netdev_dbg(dev, "\tsjw: %u\n", bt->sjw);
netdev_dbg(dev, "\tbrp: %u\n", bt->brp);
}
static void dummy_can_print_tdc(struct net_device *dev, struct can_tdc *tdc)
{
netdev_dbg(dev, "\t\ttdcv: %u\n", tdc->tdcv);
netdev_dbg(dev, "\t\ttdco: %u\n", tdc->tdco);
netdev_dbg(dev, "\t\ttdcf: %u\n", tdc->tdcf);
}
static void dummy_can_print_pwm(struct net_device *dev, struct can_pwm *pwm,
struct can_bittiming *dbt)
{
netdev_dbg(dev, "\t\tpwms: %u\n", pwm->pwms);
netdev_dbg(dev, "\t\tpwml: %u\n", pwm->pwml);
netdev_dbg(dev, "\t\tpwmo: %u\n", pwm->pwmo);
}
static void dummy_can_print_ctrlmode(struct net_device *dev)
{
struct dummy_can *priv = netdev_priv(dev);
struct can_priv *can_priv = &priv->can;
unsigned long supported = can_priv->ctrlmode_supported;
u32 enabled = can_priv->ctrlmode;
netdev_dbg(dev, "Control modes:\n");
netdev_dbg(dev, "\tsupported: 0x%08x\n", (u32)supported);
netdev_dbg(dev, "\tenabled: 0x%08x\n", enabled);
if (supported) {
int idx;
netdev_dbg(dev, "\tlist:");
for_each_set_bit(idx, &supported, BITS_PER_TYPE(u32))
netdev_dbg(dev, "\t\t%s: %s\n",
can_get_ctrlmode_str(BIT(idx)),
enabled & BIT(idx) ? "on" : "off");
}
}
static void dummy_can_print_bittiming_info(struct net_device *dev)
{
struct dummy_can *priv = netdev_priv(dev);
struct can_priv *can_priv = &priv->can;
netdev_dbg(dev, "Clock frequency: %u\n", can_priv->clock.freq);
netdev_dbg(dev, "Maximum bitrate: %u\n", can_priv->bitrate_max);
netdev_dbg(dev, "MTU: %u\n", dev->mtu);
netdev_dbg(dev, "\n");
dummy_can_print_ctrlmode(dev);
netdev_dbg(dev, "\n");
netdev_dbg(dev, "Classical CAN nominal bittiming:\n");
dummy_can_print_bittiming(dev, &can_priv->bittiming);
netdev_dbg(dev, "\n");
if (can_priv->ctrlmode & CAN_CTRLMODE_FD) {
netdev_dbg(dev, "CAN FD databittiming:\n");
dummy_can_print_bittiming(dev, &can_priv->fd.data_bittiming);
if (can_fd_tdc_is_enabled(can_priv)) {
netdev_dbg(dev, "\tCAN FD TDC:\n");
dummy_can_print_tdc(dev, &can_priv->fd.tdc);
}
}
netdev_dbg(dev, "\n");
if (can_priv->ctrlmode & CAN_CTRLMODE_XL) {
netdev_dbg(dev, "CAN XL databittiming:\n");
dummy_can_print_bittiming(dev, &can_priv->xl.data_bittiming);
if (can_xl_tdc_is_enabled(can_priv)) {
netdev_dbg(dev, "\tCAN XL TDC:\n");
dummy_can_print_tdc(dev, &can_priv->xl.tdc);
}
if (can_priv->ctrlmode & CAN_CTRLMODE_XL_TMS) {
netdev_dbg(dev, "\tCAN XL PWM:\n");
dummy_can_print_pwm(dev, &can_priv->xl.pwm,
&can_priv->xl.data_bittiming);
}
}
netdev_dbg(dev, "\n");
}
static int dummy_can_netdev_open(struct net_device *dev)
{
int ret;
struct can_priv *priv = netdev_priv(dev);
dummy_can_print_bittiming_info(dev);
netdev_dbg(dev, "error-signalling is %s\n",
str_enabled_disabled(!can_dev_in_xl_only_mode(priv)));
ret = open_candev(dev);
if (ret)
return ret;
netif_start_queue(dev);
netdev_dbg(dev, "dummy-can is up\n");
return 0;
}
static int dummy_can_netdev_close(struct net_device *dev)
{
netif_stop_queue(dev);
close_candev(dev);
netdev_dbg(dev, "dummy-can is down\n");
return 0;
}
static netdev_tx_t dummy_can_start_xmit(struct sk_buff *skb,
struct net_device *dev)
{
if (can_dev_dropped_skb(dev, skb))
return NETDEV_TX_OK;
can_put_echo_skb(skb, dev, 0, 0);
dev->stats.tx_packets++;
dev->stats.tx_bytes += can_get_echo_skb(dev, 0, NULL);
return NETDEV_TX_OK;
}
static const struct net_device_ops dummy_can_netdev_ops = {
.ndo_open = dummy_can_netdev_open,
.ndo_stop = dummy_can_netdev_close,
.ndo_start_xmit = dummy_can_start_xmit,
};
static const struct ethtool_ops dummy_can_ethtool_ops = {
.get_ts_info = ethtool_op_get_ts_info,
};
static int __init dummy_can_init(void)
{
struct net_device *dev;
struct dummy_can *priv;
int ret;
dev = alloc_candev(sizeof(*priv), 1);
if (!dev)
return -ENOMEM;
dev->netdev_ops = &dummy_can_netdev_ops;
dev->ethtool_ops = &dummy_can_ethtool_ops;
priv = netdev_priv(dev);
priv->can.bittiming_const = &dummy_can_bittiming_const;
priv->can.bitrate_max = 20 * MEGA /* BPS */;
priv->can.clock.freq = 160 * MEGA /* Hz */;
priv->can.fd.data_bittiming_const = &dummy_can_fd_databittiming_const;
priv->can.fd.tdc_const = &dummy_can_fd_tdc_const;
priv->can.xl.data_bittiming_const = &dummy_can_xl_databittiming_const;
priv->can.xl.tdc_const = &dummy_can_xl_tdc_const;
priv->can.xl.pwm_const = &dummy_can_pwm_const;
priv->can.ctrlmode_supported = CAN_CTRLMODE_LISTENONLY |
CAN_CTRLMODE_FD | CAN_CTRLMODE_TDC_AUTO |
CAN_CTRLMODE_RESTRICTED | CAN_CTRLMODE_XL |
CAN_CTRLMODE_XL_TDC_AUTO | CAN_CTRLMODE_XL_TMS;
priv->dev = dev;
ret = register_candev(priv->dev);
if (ret) {
free_candev(priv->dev);
return ret;
}
dummy_can = priv;
netdev_dbg(dev, "dummy-can ready\n");
return 0;
}
static void __exit dummy_can_exit(void)
{
struct net_device *dev = dummy_can->dev;
netdev_dbg(dev, "dummy-can bye bye\n");
unregister_candev(dev);
free_candev(dev);
}
module_init(dummy_can_init);
module_exit(dummy_can_exit);
MODULE_DESCRIPTION("A dummy CAN driver, mainly to test the netlink interface");
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Vincent Mailhol <mailhol@kernel.org>");
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