Message-ID: <61adf428-2205-1563-d0b6-fa843e08559d@linux.intel.com>
Date: Mon, 6 May 2024 19:24:53 +0300 (EEST)
From: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To: Christoph Fritz <christoph.fritz@...dev.de>
cc: Jiri Slaby <jirislaby@...nel.org>, 
    Oliver Hartkopp <socketcan@...tkopp.net>, 
    Marc Kleine-Budde <mkl@...gutronix.de>, 
    Vincent Mailhol <mailhol.vincent@...adoo.fr>, 
    "David S . Miller" <davem@...emloft.net>, 
    Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, 
    Paolo Abeni <pabeni@...hat.com>, Rob Herring <robh@...nel.org>, 
    Krzysztof Kozlowski <krzk+dt@...nel.org>, 
    Conor Dooley <conor+dt@...nel.org>, Jiri Kosina <jikos@...nel.org>, 
    Benjamin Tissoires <bentiss@...nel.org>, 
    Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
    Sebastian Reichel <sre@...nel.org>, 
    Linus Walleij <linus.walleij@...aro.org>, 
    Andreas Lauser <andreas.lauser@...cedes-benz.com>, 
    Jonathan Corbet <corbet@....net>, Pavel Pisa <pisa@....felk.cvut.cz>, 
    linux-can@...r.kernel.org, netdev@...r.kernel.org, 
    devicetree@...r.kernel.org, linux-input@...r.kernel.org, 
    linux-serial@...r.kernel.org
Subject: Re: [PATCH v3 01/11] can: Add LIN bus as CAN abstraction

On Thu, 2 May 2024, Christoph Fritz wrote:

> This patch adds a LIN (local interconnect network) bus abstraction on
> top of CAN.  It is a glue driver adapting CAN on one side while offering
> LIN abstraction on the other side. So that upcoming LIN device drivers
> can make use of it.
> 
> Tested-by: Andreas Lauser <andreas.lauser@...cedes-benz.com>
> Signed-off-by: Christoph Fritz <christoph.fritz@...dev.de>
> ---
>  drivers/net/can/Kconfig          |  10 +
>  drivers/net/can/Makefile         |   1 +
>  drivers/net/can/lin.c            | 495 +++++++++++++++++++++++++++++++
>  include/net/lin.h                |  92 ++++++
>  include/uapi/linux/can/netlink.h |   1 +
>  5 files changed, 599 insertions(+)
>  create mode 100644 drivers/net/can/lin.c
>  create mode 100644 include/net/lin.h
> 
> diff --git a/drivers/net/can/Kconfig b/drivers/net/can/Kconfig
> index 2e31db55d9278..0934bbf8d03b2 100644
> --- a/drivers/net/can/Kconfig
> +++ b/drivers/net/can/Kconfig
> @@ -171,6 +171,16 @@ config CAN_KVASER_PCIEFD
>  	    Kvaser M.2 PCIe 4xCAN
>  	    Kvaser PCIe 8xCAN
>  
> +config CAN_LIN
> +	tristate "LIN mode support"
> +	help
> +	  This is a glue driver for LIN-BUS support.
> +
> +	  The local interconnect (LIN) bus is a simple bus with a feature
> +	  subset of CAN. It is often combined with CAN for simple controls.
> +
> +	  Actual device drivers need to be enabled too.
> +
>  config CAN_SLCAN
>  	tristate "Serial / USB serial CAN Adaptors (slcan)"
>  	depends on TTY
> diff --git a/drivers/net/can/Makefile b/drivers/net/can/Makefile
> index 4669cd51e7bf5..0093ee9219ca8 100644
> --- a/drivers/net/can/Makefile
> +++ b/drivers/net/can/Makefile
> @@ -25,6 +25,7 @@ obj-$(CONFIG_CAN_GRCAN)		+= grcan.o
>  obj-$(CONFIG_CAN_IFI_CANFD)	+= ifi_canfd/
>  obj-$(CONFIG_CAN_JANZ_ICAN3)	+= janz-ican3.o
>  obj-$(CONFIG_CAN_KVASER_PCIEFD)	+= kvaser_pciefd.o
> +obj-$(CONFIG_CAN_LIN)		+= lin.o
>  obj-$(CONFIG_CAN_MSCAN)		+= mscan/
>  obj-$(CONFIG_CAN_M_CAN)		+= m_can/
>  obj-$(CONFIG_CAN_PEAK_PCIEFD)	+= peak_canfd/
> diff --git a/drivers/net/can/lin.c b/drivers/net/can/lin.c
> new file mode 100644
> index 0000000000000..95906003666fb
> --- /dev/null
> +++ b/drivers/net/can/lin.c
> @@ -0,0 +1,495 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/* Copyright (C) 2024 hexDEV GmbH - https://hexdev.de */
> +
> +#include <linux/can/core.h>
> +#include <linux/can/dev.h>
> +#include <linux/can/error.h>
> +#include <linux/module.h>
> +#include <linux/device.h>
> +#include <linux/netdevice.h>
> +#include <linux/init.h>
> +#include <linux/kernel.h>
> +#include <net/lin.h>
> +
> +static const u8 lin_id_parity_tbl[] = {
> +	0x80, 0xC0, 0x40, 0x00, 0xC0, 0x80, 0x00, 0x40,
> +	0x00, 0x40, 0xC0, 0x80, 0x40, 0x00, 0x80, 0xC0,
> +	0x40, 0x00, 0x80, 0xC0, 0x00, 0x40, 0xC0, 0x80,
> +	0xC0, 0x80, 0x00, 0x40, 0x80, 0xC0, 0x40, 0x00,
> +	0x00, 0x40, 0xC0, 0x80, 0x40, 0x00, 0x80, 0xC0,
> +	0x80, 0xC0, 0x40, 0x00, 0xC0, 0x80, 0x00, 0x40,
> +	0xC0, 0x80, 0x00, 0x40, 0x80, 0xC0, 0x40, 0x00,
> +	0x40, 0x00, 0x80, 0xC0, 0x00, 0x40, 0xC0, 0x80,
> +};
> +
> +u8 lin_get_id_parity(u8 id)
> +{
> +	return lin_id_parity_tbl[id];
> +}
> +EXPORT_SYMBOL(lin_get_id_parity);
> +
> +static ssize_t lin_identifier_show(struct kobject *kobj,
> +				   struct kobj_attribute *attr, char *buf)
> +{
> +	struct lin_attr *lin_attr = container_of(attr, struct lin_attr, attr);
> +	struct lin_device *ldev = lin_attr->ldev;
> +	ssize_t count = 0;
> +	struct lin_responder_answer answ;
> +	int k, ret;
> +	long id;
> +
> +	if (!ldev->ldev_ops->get_responder_answer)
> +		return -EOPNOTSUPP;
> +
> +	ret = kstrtol(attr->attr.name, 16, &id);
> +	if (ret)
> +		return ret;
> +	if (id < 0 || id >= LIN_NUM_IDS)
> +		return -EINVAL;
> +
> +	count += scnprintf(buf + count, PAGE_SIZE - count,
> +			   "%-6s %-11s %-9s %-9s %-2s %-24s %-6s\n",
> +			   "state", "cksum-mode", "is_event", "event_id",
> +			   "n", "data", "cksum");

Onl use sysfs_emit() and sysfs_emit_at() in *_show functions.

> +
> +	ret = ldev->ldev_ops->get_responder_answer(ldev, id, &answ);
> +	if (ret)
> +		return ret;
> +
> +	count += scnprintf(buf + count, PAGE_SIZE - count,
> +			   "%-6s %-11s %-9s %-9u %-2u ",
> +			   answ.is_active ? "active" : "off",
> +			   answ.lf.checksum_mode ? "enhanced" : "classic",
> +			   answ.is_event_frame ? "yes" : "no",
> +			   answ.event_associated_id,
> +			   answ.lf.len);
> +
> +	for (k = 0; k < answ.lf.len; k++)
> +		count += scnprintf(buf + count, PAGE_SIZE - count,
> +				   "%02x ", answ.lf.data[k]);
> +	for (; k < 8; k++)
> +		count += scnprintf(buf + count, PAGE_SIZE - count,
> +				   "   ");
> +	if (answ.lf.len)
> +		count += scnprintf(buf + count, PAGE_SIZE - count,
> +				   " %02x", answ.lf.checksum);
> +
> +	count += scnprintf(buf + count, PAGE_SIZE - count, "\n");
> +
> +	return count;
> +}
> +
> +static const char *parse_and_advance(const char *buf, long *result,
> +				     unsigned int base)
> +{
> +	char num_str[5] = {0};
> +	int num_len = 0;
> +
> +	while (*buf && isspace(*buf))
> +		buf++;
> +	while (*buf && isalnum(*buf) && num_len < sizeof(num_str) - 1)
> +		num_str[num_len++] = *buf++;
> +	if (kstrtol(num_str, base, result))
> +		return NULL;
> +
> +	return buf;
> +}
> +
> +static ssize_t lin_identifier_store(struct kobject *kobj,
> +				    struct kobj_attribute *attr,
> +				    const char *buf, size_t count)
> +{
> +	struct lin_attr *lin_attr = container_of(attr, struct lin_attr, attr);
> +	struct lin_device *ldev = lin_attr->ldev;
> +	struct lin_responder_answer answ = { 0 };
> +	const char *ptr = buf;
> +	int ret;
> +	long v;
> +
> +	if (!ldev->ldev_ops->update_responder_answer)
> +		return -EOPNOTSUPP;
> +
> +	ret = kstrtol(attr->attr.name, 16, &v);
> +	if (ret)
> +		return ret;
> +	if (v < 0 || v >= LIN_NUM_IDS)
> +		return -EINVAL;
> +	answ.lf.lin_id = v;
> +
> +	ptr = parse_and_advance(ptr, &v, 2);
> +	if (!ptr)
> +		return -EINVAL;
> +	answ.is_active = v != 0;
> +
> +	ptr = parse_and_advance(ptr, &v, 2);
> +	if (!ptr)
> +		return -EINVAL;
> +	answ.lf.checksum_mode = v != 0;
> +
> +	ptr = parse_and_advance(ptr, &v, 2);
> +	if (!ptr)
> +		return -EINVAL;
> +	answ.is_event_frame = v != 0;
> +
> +	ptr = parse_and_advance(ptr, &v, 16);
> +	if (!ptr || v > LIN_ID_MASK)
> +		return -EINVAL;
> +	answ.event_associated_id = v;
> +
> +	ptr = parse_and_advance(ptr, &v, 16);
> +	if (!ptr || v > LIN_MAX_DLEN)
> +		return -EINVAL;
> +	answ.lf.len = v;
> +
> +	for (int i = 0; i < answ.lf.len; i++) {
> +		ptr = parse_and_advance(ptr, &v, 16);
> +		if (!ptr)
> +			return -EINVAL;
> +		answ.lf.data[i] = v;
> +	}
> +
> +	ret = ldev->ldev_ops->update_responder_answer(ldev, &answ);
> +	if (ret)
> +		return ret;
> +
> +	return count;
> +}
> +
> +static int lin_create_sysfs_id_files(struct net_device *ndev)
> +{
> +	struct lin_device *ldev = netdev_priv(ndev);
> +	struct kobj_attribute *attr;
> +	int ret;
> +
> +	for (int id = 0; id < LIN_NUM_IDS; id++) {
> +		ldev->sysfs_entries[id].ldev = ldev;
> +		attr = &ldev->sysfs_entries[id].attr;
> +		attr->attr.name = kasprintf(GFP_KERNEL, "%02x", id);
> +		if (!attr->attr.name)
> +			return -ENOMEM;
> +		attr->attr.mode = 0644;
> +		attr->show = lin_identifier_show;
> +		attr->store = lin_identifier_store;
> +
> +		sysfs_attr_init(&attr->attr);
> +		ret = sysfs_create_file(ldev->lin_ids_kobj, &attr->attr);
> +		if (ret) {
> +			kfree(attr->attr.name);
> +			return -ENOMEM;
> +		}
> +	}
> +
> +	return 0;
> +}

Can you use .dev_groups instead ?

FWIW, this function doesn't do rollback when error occurs.

> +
> +static void lin_remove_sysfs_id_files(struct net_device *ndev)
> +{
> +	struct lin_device *ldev = netdev_priv(ndev);
> +	struct kobj_attribute *attr;
> +
> +	for (int id = 0; id < LIN_NUM_IDS; id++) {
> +		attr = &ldev->sysfs_entries[id].attr;
> +		sysfs_remove_file(ldev->lin_ids_kobj, &attr->attr);
> +		kfree(attr->attr.name);
> +	}
> +}
> +
> +static void lin_tx_work_handler(struct work_struct *ws)
> +{
> +	struct lin_device *ldev = container_of(ws, struct lin_device,
> +					       tx_work);
> +	struct net_device *ndev = ldev->ndev;
> +	struct canfd_frame *cfd;
> +	struct lin_frame lf;
> +	int ret;
> +
> +	ldev->tx_busy = true;
> +
> +	cfd = (struct canfd_frame *)ldev->tx_skb->data;
> +	lf.checksum_mode = (cfd->can_id & LIN_ENHANCED_CKSUM_FLAG) ?
> +			   LINBUS_ENHANCED : LINBUS_CLASSIC;
> +	lf.lin_id = cfd->can_id & LIN_ID_MASK;
> +	lf.len = min(cfd->len, LIN_MAX_DLEN);
> +	memcpy(lf.data, cfd->data, lf.len);
> +
> +	ret = ldev->ldev_ops->ldo_tx(ldev, &lf);
> +	if (ret) {
> +		DEV_STATS_INC(ndev, tx_dropped);
> +		netdev_err_once(ndev, "transmission failure %d\n", ret);
> +		goto lin_tx_out;
> +	}
> +
> +	DEV_STATS_INC(ndev, tx_packets);
> +	DEV_STATS_ADD(ndev, tx_bytes, lf.len);
> +
> +lin_tx_out:
> +	ldev->tx_busy = false;
> +	netif_wake_queue(ndev);
> +}
> +
> +static netdev_tx_t lin_start_xmit(struct sk_buff *skb,
> +				  struct net_device *ndev)
> +{
> +	struct lin_device *ldev = netdev_priv(ndev);
> +
> +	if (ldev->tx_busy)
> +		return NETDEV_TX_BUSY;
> +
> +	netif_stop_queue(ndev);
> +	ldev->tx_skb = skb;
> +	queue_work(ldev->wq, &ldev->tx_work);
> +
> +	return NETDEV_TX_OK;
> +}
> +
> +static int lin_open(struct net_device *ndev)
> +{
> +	struct lin_device *ldev = netdev_priv(ndev);
> +	int ret;
> +
> +	ldev->tx_busy = false;
> +
> +	ret = open_candev(ndev);
> +	if (ret)
> +		return ret;
> +
> +	netif_wake_queue(ndev);
> +
> +	ldev->can.state = CAN_STATE_ERROR_ACTIVE;
> +	ndev->mtu = CANFD_MTU;
> +
> +	return ldev->ldev_ops->ldo_open(ldev);
> +}
> +
> +static int lin_stop(struct net_device *ndev)
> +{
> +	struct lin_device *ldev = netdev_priv(ndev);
> +
> +	close_candev(ndev);
> +
> +	flush_work(&ldev->tx_work);
> +
> +	ldev->can.state = CAN_STATE_STOPPED;
> +
> +	return ldev->ldev_ops->ldo_stop(ldev);
> +}
> +
> +static const struct net_device_ops lin_netdev_ops = {
> +	.ndo_open = lin_open,
> +	.ndo_stop = lin_stop,
> +	.ndo_start_xmit = lin_start_xmit,
> +	.ndo_change_mtu = can_change_mtu,
> +};
> +
> +u8 lin_get_checksum(u8 pid, u8 n_of_bytes, const u8 *bytes,
> +		    enum lin_checksum_mode cm)
> +{
> +	unsigned int csum = 0;
> +	int i;
> +
> +	if (cm == LINBUS_ENHANCED)
> +		csum += pid;
> +
> +	for (i = 0; i < n_of_bytes; i++) {
> +		csum += bytes[i];
> +		if (csum > 255)
> +			csum -= 255;
> +	}
> +
> +	return (~csum & 0xff);
> +}
> +EXPORT_SYMBOL_GPL(lin_get_checksum);
> +
> +static int lin_bump_rx_err(struct lin_device *ldev, const struct lin_frame *lf)
> +{
> +	struct net_device *ndev = ldev->ndev;
> +	struct can_frame cf = {0 };
> +
> +	if (lf->lin_id > LIN_ID_MASK) {
> +		netdev_dbg(ndev, "id exceeds LIN max id\n");
> +		cf.can_id = CAN_ERR_FLAG | CAN_ERR_PROT;
> +		cf.data[3] = CAN_ERR_PROT_LOC_ID12_05;
> +	}
> +
> +	if (lf->len > LIN_MAX_DLEN) {
> +		netdev_dbg(ndev, "frame exceeds number of bytes\n");
> +		cf.can_id = CAN_ERR_FLAG | CAN_ERR_PROT;
> +		cf.data[3] = CAN_ERR_PROT_LOC_DLC;
> +	}
> +
> +	if (lf->len) {
> +		u8 checksum = lin_get_checksum(LIN_FORM_PID(lf->lin_id),
> +					       lf->len, lf->data,
> +					       lf->checksum_mode);
> +
> +		if (checksum != lf->checksum) {
> +			netdev_dbg(ndev, "expected cksm: 0x%02x got: 0x%02x\n",
> +				   checksum, lf->checksum);
> +			cf.can_id = CAN_ERR_FLAG | CAN_ERR_PROT;
> +			cf.data[2] = CAN_ERR_PROT_FORM;
> +		}
> +	}
> +
> +	if (cf.can_id & CAN_ERR_FLAG) {
> +		struct can_frame *err_cf;
> +		struct sk_buff *skb = alloc_can_err_skb(ndev, &err_cf);
> +
> +		if (unlikely(!skb))
> +			return -ENOMEM;
> +
> +		err_cf->can_id |= cf.can_id;
> +		memcpy(err_cf->data, cf.data, CAN_MAX_DLEN);
> +
> +		netif_rx(skb);
> +
> +		return -EREMOTEIO;
> +	}
> +
> +	return 0;
> +}
> +
> +int lin_rx(struct lin_device *ldev, const struct lin_frame *lf)
> +{
> +	struct net_device *ndev = ldev->ndev;
> +	struct can_frame *cf;
> +	struct sk_buff *skb;
> +	int ret;
> +
> +	if (ldev->can.state == CAN_STATE_STOPPED)
> +		return 0;
> +
> +	netdev_dbg(ndev, "id:%02x, len:%u, data:%*ph, checksum:%02x (%s)\n",
> +		   lf->lin_id, lf->len, lf->len, lf->data, lf->checksum,
> +		   lf->checksum_mode ? "enhanced" : "classic");
> +
> +	ret = lin_bump_rx_err(ldev, lf);
> +	if (ret) {
> +		DEV_STATS_INC(ndev, rx_dropped);
> +		return ret;
> +	}
> +
> +	skb = alloc_can_skb(ndev, &cf);
> +	if (unlikely(!skb)) {
> +		DEV_STATS_INC(ndev, rx_dropped);
> +		return -ENOMEM;
> +	}
> +
> +	cf->can_id = lf->lin_id;
> +	cf->len = min(lf->len, LIN_MAX_DLEN);
> +	memcpy(cf->data, lf->data, cf->len);
> +
> +	DEV_STATS_INC(ndev, rx_packets);
> +	DEV_STATS_ADD(ndev, rx_bytes, cf->len);
> +
> +	netif_receive_skb(skb);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(lin_rx);
> +
> +static int lin_set_bittiming(struct net_device *ndev)
> +{
> +	struct lin_device *ldev = netdev_priv(ndev);
> +	unsigned int bitrate = ldev->can.bittiming.bitrate;
> +
> +	return ldev->ldev_ops->update_bitrate(ldev, bitrate);
> +}
> +
> +static const u32 lin_bitrate[] = { 1200, 2400, 4800, 9600, 19200 };
> +
> +struct lin_device *register_lin(struct device *dev,
> +				const struct lin_device_ops *ldops)
> +{
> +	struct net_device *ndev;
> +	struct lin_device *ldev;
> +	int ret;
> +
> +	if (!ldops || !ldops->ldo_tx || !ldops->update_bitrate  ||
> +	    !ldops->ldo_open || !ldops->ldo_stop) {
> +		netdev_err(ndev, "missing mandatory lin_device_ops\n");
> +		return ERR_PTR(-EINVAL);
> +	}
> +
> +	ndev = alloc_candev(sizeof(struct lin_device), 1);
> +	if (!ndev)
> +		return ERR_PTR(-ENOMEM);
> +
> +	ldev = netdev_priv(ndev);
> +
> +	ldev->ldev_ops = ldops;
> +	ndev->netdev_ops = &lin_netdev_ops;
> +	ndev->flags |= IFF_ECHO;
> +	ndev->mtu = CANFD_MTU;
> +	ldev->can.bittiming.bitrate = LIN_DEFAULT_BAUDRATE;
> +	ldev->can.ctrlmode = CAN_CTRLMODE_LIN;
> +	ldev->can.ctrlmode_supported = 0;
> +	ldev->can.bitrate_const = lin_bitrate;
> +	ldev->can.bitrate_const_cnt = ARRAY_SIZE(lin_bitrate);
> +	ldev->can.do_set_bittiming = lin_set_bittiming;
> +	ldev->ndev = ndev;
> +	ldev->dev = dev;
> +
> +	SET_NETDEV_DEV(ndev, dev);
> +
> +	ret = lin_set_bittiming(ndev);
> +	if (ret) {
> +		netdev_err(ndev, "set bittiming failed\n");
> +		goto exit_candev;
> +	}
> +
> +	ret = register_candev(ndev);
> +	if (ret)
> +		goto exit_candev;
> +
> +	ldev->lin_ids_kobj = kobject_create_and_add("lin_ids", &ndev->dev.kobj);
> +	if (!ldev->lin_ids_kobj) {
> +		netdev_err(ndev, "Failed to create sysfs directory\n");
> +		ret = -ENOMEM;
> +		goto exit_unreg;
> +	}
> +
> +	ret = lin_create_sysfs_id_files(ndev);
> +	if (ret) {
> +		netdev_err(ndev, "Failed to create sysfs entry: %d\n", ret);
> +		goto exit_kobj_put;
> +	}
> +
> +	/* Using workqueue as tx over USB/SPI/... may sleep */
> +	ldev->wq = alloc_workqueue(dev_name(dev), WQ_FREEZABLE | WQ_MEM_RECLAIM,
> +				   0);
> +	if (!ldev->wq)
> +		goto exit_rm_files;
> +
> +	INIT_WORK(&ldev->tx_work, lin_tx_work_handler);
> +
> +	netdev_info(ndev, "LIN initialized.\n");
> +
> +	return ldev;
> +
> +exit_rm_files:
> +	lin_remove_sysfs_id_files(ndev);
> +exit_kobj_put:
> +	kobject_put(ldev->lin_ids_kobj);
> +exit_unreg:
> +	unregister_candev(ndev);
> +exit_candev:
> +	free_candev(ndev);
> +	return ERR_PTR(ret);
> +}
> +EXPORT_SYMBOL_GPL(register_lin);
> +
> +void unregister_lin(struct lin_device *ldev)
> +{
> +	struct net_device *ndev = ldev->ndev;
> +
> +	lin_remove_sysfs_id_files(ndev);
> +	kobject_put(ldev->lin_ids_kobj);
> +	unregister_candev(ndev);
> +	destroy_workqueue(ldev->wq);
> +	free_candev(ndev);
> +}
> +EXPORT_SYMBOL_GPL(unregister_lin);
> +
> +MODULE_LICENSE("GPL");
> +MODULE_AUTHOR("Christoph Fritz <christoph.fritz@...dev.de>");
> +MODULE_DESCRIPTION("LIN bus to CAN glue driver");
> diff --git a/include/net/lin.h b/include/net/lin.h
> new file mode 100644
> index 0000000000000..e7c7c820a6e18
> --- /dev/null
> +++ b/include/net/lin.h
> @@ -0,0 +1,92 @@
> +/* SPDX-License-Identifier: GPL-2.0+ */
> +/* Copyright (C) 2024 hexDEV GmbH - https://hexdev.de */
> +
> +#ifndef _NET_LIN_H_
> +#define _NET_LIN_H_
> +
> +#include <linux/bitfield.h>
> +#include <linux/can/dev.h>
> +#include <linux/device.h>
> +
> +#define LIN_NUM_IDS		64
> +#define LIN_HEADER_SIZE		3
> +#define LIN_MAX_DLEN		8
> +
> +#define LIN_MAX_BAUDRATE	20000
> +#define LIN_MIN_BAUDRATE	1000
> +#define LIN_DEFAULT_BAUDRATE	9600
> +#define LIN_SYNC_BYTE		0x55
> +
> +#define LIN_ID_MASK		GENMASK(5, 0)
> +/* special ID descriptions for LIN */
> +#define LIN_RXOFFLOAD_DATA_FLAG	0x00000200U
> +#define LIN_ENHANCED_CKSUM_FLAG	0x00000100U

BIT(x) x 2

> +
> +extern u8 lin_get_id_parity(u8 id);
> +
> +#define LIN_GET_ID(PID)		FIELD_GET(LIN_ID_MASK, PID)
> +#define LIN_FORM_PID(ID)	(LIN_GET_ID(ID) | \
> +					lin_get_id_parity(LIN_GET_ID(ID)))
> +#define LIN_GET_PARITY(PID)	((PID) & ~LIN_ID_MASK)
> +#define LIN_CHECK_PID(PID)	(LIN_GET_PARITY(PID) == \
> +					LIN_GET_PARITY(LIN_FORM_PID(PID)))
> +
> +struct lin_attr {
> +	struct kobj_attribute attr;
> +	struct lin_device *ldev;
> +};
> +
> +struct lin_device {
> +	struct can_priv can;  /* must be the first member */
> +	struct net_device *ndev;
> +	struct device *dev;
> +	const struct lin_device_ops *ldev_ops;
> +	struct workqueue_struct *wq;
> +	struct work_struct tx_work;
> +	bool tx_busy;
> +	struct sk_buff *tx_skb;
> +	struct kobject *lin_ids_kobj;
> +	struct lin_attr sysfs_entries[LIN_NUM_IDS];
> +};
> +
> +enum lin_checksum_mode {
> +	LINBUS_CLASSIC = 0,
> +	LINBUS_ENHANCED,
> +};
> +
> +struct lin_frame {
> +	u8 lin_id;
> +	u8 len;
> +	u8 data[LIN_MAX_DLEN];
> +	u8 checksum;
> +	enum lin_checksum_mode checksum_mode;
> +};
> +
> +struct lin_responder_answer {
> +	bool is_active;
> +	bool is_event_frame;
> +	u8 event_associated_id;
> +	struct lin_frame lf;
> +};
> +
> +struct lin_device_ops {
> +	int (*ldo_open)(struct lin_device *ldev);
> +	int (*ldo_stop)(struct lin_device *ldev);
> +	int (*ldo_tx)(struct lin_device *ldev, const struct lin_frame *frame);
> +	int (*update_bitrate)(struct lin_device *ldev, u16 bitrate);
> +	int (*update_responder_answer)(struct lin_device *ldev,
> +				       const struct lin_responder_answer *answ);
> +	int (*get_responder_answer)(struct lin_device *ldev, u8 id,
> +				    struct lin_responder_answer *answ);
> +};
> +
> +int lin_rx(struct lin_device *ldev, const struct lin_frame *lf);
> +
> +u8 lin_get_checksum(u8 pid, u8 n_of_bytes, const u8 *bytes,
> +		    enum lin_checksum_mode cm);
> +
> +struct lin_device *register_lin(struct device *dev,
> +				const struct lin_device_ops *ldops);
> +void unregister_lin(struct lin_device *ldev);
> +
> +#endif /* _NET_LIN_H_ */
> diff --git a/include/uapi/linux/can/netlink.h b/include/uapi/linux/can/netlink.h
> index 02ec32d694742..51b0e2a7624e4 100644
> --- a/include/uapi/linux/can/netlink.h
> +++ b/include/uapi/linux/can/netlink.h
> @@ -103,6 +103,7 @@ struct can_ctrlmode {
>  #define CAN_CTRLMODE_CC_LEN8_DLC	0x100	/* Classic CAN DLC option */
>  #define CAN_CTRLMODE_TDC_AUTO		0x200	/* CAN transiver automatically calculates TDCV */
>  #define CAN_CTRLMODE_TDC_MANUAL		0x400	/* TDCV is manually set up by user */

BIT(x) is these days available also for uapi I think.

> +#define CAN_CTRLMODE_LIN		0x800	/* LIN bus mode */
>  
>  /*
>   * CAN device statistics
> 

-- 
 i.

Powered by blists - more mailing lists