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@xxxxxxxxxxxxxxxxx> Signed-off-by: Christoph Fritz <christoph.fritz@xxxxxxxxx> --- drivers/net/can/Kconfig | 10 + drivers/net/can/Makefile | 1 + drivers/net/can/lin.c | 495 +++++++++++++++++++++++++++++++ include/net/lin.h | 91 ++++++ include/uapi/linux/can/netlink.h | 1 + 5 files changed, 598 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"); + + 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; +} + +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@xxxxxxxxx>"); +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..944e775c40e79 --- /dev/null +++ b/include/net/lin.h @@ -0,0 +1,91 @@ +/* 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_ENHANCED_CKSUM_FLAG 0x00000100U + +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 */ +#define CAN_CTRLMODE_LIN 0x800 /* LIN bus mode */ /* * CAN device statistics -- 2.39.2
