This commit introduces LIN-Bus support for UART devices equipped with LIN transceivers, utilizing the Serial Device Bus (serdev) interface. For more details on an adapter, visit: https://hexdev.de/hexlin#tty Signed-off-by: Christoph Fritz <christoph.fritz@xxxxxxxxx> --- drivers/net/can/Kconfig | 16 ++ drivers/net/can/Makefile | 1 + drivers/net/can/lin-serdev.c | 467 +++++++++++++++++++++++++++++++++++ 3 files changed, 484 insertions(+) create mode 100644 drivers/net/can/lin-serdev.c diff --git a/drivers/net/can/Kconfig b/drivers/net/can/Kconfig index 0934bbf8d03b2..b930eaea9b235 100644 --- a/drivers/net/can/Kconfig +++ b/drivers/net/can/Kconfig @@ -181,6 +181,22 @@ config CAN_LIN Actual device drivers need to be enabled too. +config CAN_LIN_SERDEV + tristate "Serial LIN Adaptors" + depends on CAN_LIN && SERIAL_DEV_BUS && OF + help + LIN-Bus support for UART devices equipped with LIN transceievers. + This device driver is using CAN_LIN for a userland connection on + one side and the kernel its serial device bus (serdev) interface + on the other side. + + If you have a hexlin tty adapter, say Y here and see + <https://hexdev.de/hexlin#tty>. + + This driver can also be built as a module. If so, the module will be + called lin-serdev.ko. + + 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 0093ee9219ca8..21ca514a42439 100644 --- a/drivers/net/can/Makefile +++ b/drivers/net/can/Makefile @@ -26,6 +26,7 @@ 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-$(CONFIG_CAN_LIN_SERDEV) += lin-serdev.o obj-$(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-serdev.c b/drivers/net/can/lin-serdev.c new file mode 100644 index 0000000000000..18e842c39f111 --- /dev/null +++ b/drivers/net/can/lin-serdev.c @@ -0,0 +1,467 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* Copyright (C) 2024 hexDEV GmbH - https://hexdev.de */ + +#include <linux/module.h> +#include <linux/wait.h> +#include <linux/init.h> +#include <linux/errno.h> +#include <linux/string.h> +#include <linux/kernel.h> +#include <net/lin.h> +#include <linux/of.h> +#include <linux/serdev.h> +#include <linux/slab.h> +#include <linux/kfifo.h> +#include <linux/workqueue.h> +#include <linux/tty.h> + +#define LINSER_SAMPLES_PER_CHAR 10 +#define LINSER_TX_BUFFER_SIZE 11 +#define LINSER_RX_FIFO_SIZE 256 +#define LINSER_PARSE_BUFFER 24 + +struct linser_rx { + u8 data; + u8 flag; +}; + +enum linser_rx_status { + NEED_MORE = -1, + MODE_OK = 0, + NEED_FORCE, +}; + +struct linser_priv { + struct lin_device *lin_dev; + struct serdev_device *serdev; + DECLARE_KFIFO_PTR(rx_fifo, struct linser_rx); + struct delayed_work rx_work; + ulong break_usleep_min; + ulong break_usleep_max; + ulong post_break_usleep_min; + ulong post_break_usleep_max; + ulong force_timeout_jfs; + struct lin_responder_answer respond_answ[LIN_NUM_IDS]; + struct mutex resp_lock; /* protects respond_answ */ +}; + +static int linser_get_responder_answer(struct lin_device *ldev, u8 id, + struct lin_responder_answer *answ) +{ + struct serdev_device *serdev = to_serdev_device(ldev->dev); + struct linser_priv *priv = serdev_device_get_drvdata(serdev); + struct lin_responder_answer *r = &priv->respond_answ[id]; + + if (!answ) + return -EINVAL; + + mutex_lock(&priv->resp_lock); + memcpy(answ, r, sizeof(struct lin_responder_answer)); + mutex_unlock(&priv->resp_lock); + + return 0; +} + +static int linser_update_resp_answer(struct lin_device *ldev, + const struct lin_responder_answer *answ) +{ + struct serdev_device *serdev = to_serdev_device(ldev->dev); + struct linser_priv *priv = serdev_device_get_drvdata(serdev); + struct lin_responder_answer *r = &priv->respond_answ[answ->lf.lin_id]; + + if (!answ) + return -EINVAL; + + mutex_lock(&priv->resp_lock); + memcpy(r, answ, sizeof(struct lin_responder_answer)); + r->lf.checksum = lin_get_checksum(LIN_FORM_PID(answ->lf.lin_id), + answ->lf.len, + answ->lf.data, + answ->lf.checksum_mode); + mutex_unlock(&priv->resp_lock); + + return 0; +} + +static int linser_send_break(struct linser_priv *priv) +{ + struct serdev_device *serdev = priv->serdev; + int ret; + + ret = serdev_device_break_ctl(serdev, -1); + if (ret) + return ret; + usleep_range(priv->break_usleep_min, priv->break_usleep_max); + + ret = serdev_device_break_ctl(serdev, 0); + if (ret) + return ret; + usleep_range(priv->post_break_usleep_min, priv->post_break_usleep_max); + + return 0; +} + +static int linser_ldo_tx(struct lin_device *ldev, const struct lin_frame *lf) +{ + struct serdev_device *serdev = to_serdev_device(ldev->dev); + struct linser_priv *priv = serdev_device_get_drvdata(serdev); + u8 pid = LIN_FORM_PID(lf->lin_id); + u8 buf[LINSER_TX_BUFFER_SIZE]; + ssize_t written_len, total_len; + u8 checksum; + int ret; + + if (lf->len + 3 > LINSER_TX_BUFFER_SIZE) { + dev_err(&serdev->dev, "Frame length %u exceeds buffer size\n", lf->len); + return -EINVAL; + } + + buf[0] = LIN_SYNC_BYTE; + buf[1] = pid; + total_len = 2; + + if (lf->len) { + memcpy(&buf[2], lf->data, lf->len); + checksum = lin_get_checksum(pid, lf->len, lf->data, + lf->checksum_mode); + buf[lf->len + 2] = checksum; + total_len += lf->len + 1; + } + + ret = linser_send_break(priv); + if (ret) + return ret; + + written_len = serdev_device_write(serdev, buf, total_len, 0); + if (written_len < total_len) + return written_len < 0 ? (int)written_len : -EIO; + + dev_dbg(&serdev->dev, "sent out: %*ph\n", (int)total_len, buf); + + serdev_device_wait_until_sent(serdev, 0); + + return 0; +} + +static void linser_derive_timings(struct linser_priv *priv, u16 bitrate) +{ + unsigned long break_baud = (bitrate * 2) / 3; + unsigned long timeout_us; + + priv->break_usleep_min = (1000000UL * LINSER_SAMPLES_PER_CHAR) / + break_baud; + priv->break_usleep_max = priv->break_usleep_min + 50; + priv->post_break_usleep_min = (1000000UL * 1 /* 1 bit */) / break_baud; + priv->post_break_usleep_max = priv->post_break_usleep_min + 30; + + timeout_us = DIV_ROUND_CLOSEST(1000000UL * 256 /* bit */, bitrate); + priv->force_timeout_jfs = usecs_to_jiffies(timeout_us); +} + +static int linser_update_bitrate(struct lin_device *ldev, u16 bitrate) +{ + struct serdev_device *serdev = to_serdev_device(ldev->dev); + struct linser_priv *priv = serdev_device_get_drvdata(serdev); + unsigned int speed; + + speed = serdev_device_set_baudrate(serdev, bitrate); + if (!bitrate || speed != bitrate) + return -EINVAL; + + linser_derive_timings(priv, bitrate); + + return 0; +} + +static struct lin_device_ops linser_lindev_ops = { + .ldo_tx = linser_ldo_tx, + .update_bitrate = linser_update_bitrate, + .get_responder_answer = linser_get_responder_answer, + .update_responder_answer = linser_update_resp_answer, +}; + +static bool linser_tx_frame_as_responder(struct linser_priv *priv, u8 id) +{ + struct lin_responder_answer *answ = &priv->respond_answ[id]; + struct serdev_device *serdev = priv->serdev; + u8 buf[LINSER_TX_BUFFER_SIZE]; + u8 checksum, count, n; + ssize_t write_len; + + mutex_lock(&priv->resp_lock); + + if (!answ->is_active) + goto unlock_and_exit_false; + + if (answ->is_event_frame) { + struct lin_responder_answer *e_answ; + + e_answ = &priv->respond_answ[answ->event_associated_id]; + n = min(e_answ->lf.len, LIN_MAX_DLEN); + if (memcmp(answ->lf.data, e_answ->lf.data, n) != 0) { + memcpy(answ->lf.data, e_answ->lf.data, n); + checksum = lin_get_checksum(LIN_FORM_PID(answ->lf.lin_id), + n, e_answ->lf.data, + answ->lf.checksum_mode); + answ = e_answ; + } else { + goto unlock_and_exit_false; + } + } else { + checksum = answ->lf.checksum; + } + + count = min(answ->lf.len, LIN_MAX_DLEN); + memcpy(&buf[0], answ->lf.data, count); + buf[count] = checksum; + + mutex_unlock(&priv->resp_lock); + + write_len = serdev_device_write(serdev, buf, count + 1, 0); + if (write_len < count + 1) + return false; + + serdev_device_wait_until_sent(serdev, 0); + + return true; + +unlock_and_exit_false: + mutex_unlock(&priv->resp_lock); + return false; +} + +static void linser_pop_fifo(struct linser_priv *priv, size_t n) +{ + struct serdev_device *serdev = priv->serdev; + struct linser_rx dummy; + size_t ret, i; + + for (i = 0; i < n; i++) { + ret = kfifo_out(&priv->rx_fifo, &dummy, 1); + if (ret != 1) { + dev_err(&serdev->dev, "Failed to pop from FIFO\n"); + break; + } + } +} + +static int linser_fill_frame(struct linser_priv *priv, struct lin_frame *lf) +{ + struct serdev_device *serdev = priv->serdev; + struct linser_rx buf[LINSER_PARSE_BUFFER]; + uint count = kfifo_out_peek(&priv->rx_fifo, buf, LINSER_PARSE_BUFFER); + uint i, brk = 0; + + memset(lf, 0, sizeof(struct lin_frame)); + + for (i = 0; i < count; i++) { + dev_dbg(&serdev->dev, "buf[%d]: data=%02x, flag=%02x\n", + i, buf[i].data, buf[i].flag); + } + + if (count < 3) + return NEED_MORE; + + if (buf[0].flag != TTY_BREAK || buf[1].data != LIN_SYNC_BYTE) { + linser_pop_fifo(priv, 1); /* pop incorrect start */ + return NEED_MORE; + } else if (!LIN_CHECK_PID(buf[2].data)) { + linser_pop_fifo(priv, 3); /* pop incorrect header */ + return NEED_MORE; + } + + lf->lin_id = LIN_GET_ID(buf[2].data); + + /* from here on we do have a correct LIN header */ + + if (count == 3) + return linser_tx_frame_as_responder(priv, lf->lin_id) ? + NEED_MORE : NEED_FORCE; + + for (i = 3; i < count && i < LINSER_PARSE_BUFFER && i < 12; i++) { + if (buf[i].flag == TTY_BREAK) { + brk = i; + break; + } + lf->len++; + } + if (lf->len) + lf->len -= 1; /* account for checksum */ + + if (brk == 3) + return MODE_OK; + + if (brk == 4) { + /* suppress wrong answer data-byte in between PID and break + * because checksum is missing + */ + return MODE_OK; + } + + for (i = 0; i < lf->len; i++) + lf->data[i] = buf[3 + i].data; + lf->checksum = buf[2 + lf->len + 1].data; + mutex_lock(&priv->resp_lock); + lf->checksum_mode = priv->respond_answ[lf->lin_id].lf.checksum_mode; + mutex_unlock(&priv->resp_lock); + + dev_dbg(&serdev->dev, "brk:%i, len:%u, data:%*ph, checksum:%x (%s)\n", + brk, lf->len, lf->len, lf->data, lf->checksum, + lf->checksum_mode ? "enhanced" : "classic"); + + if (brk > 4) + return MODE_OK; /* frame in between two breaks: so complete */ + + if (lf->len == 8) + return MODE_OK; + + return NEED_FORCE; +} + +static int linser_process_frame(struct linser_priv *priv, bool force) +{ + struct serdev_device *serdev = priv->serdev; + struct lin_frame lf; + size_t bytes_to_pop; + int ret = NEED_MORE; + + while (kfifo_len(&priv->rx_fifo) >= LIN_HEADER_SIZE) { + ret = linser_fill_frame(priv, &lf); + + if (ret == MODE_OK || (ret == NEED_FORCE && force)) { + dev_dbg(&serdev->dev, "lin_rx: %s\n", + force ? "force" : "normal"); + lin_rx(priv->lin_dev, &lf); + bytes_to_pop = LIN_HEADER_SIZE + lf.len + + (lf.len ? 1 : 0); + linser_pop_fifo(priv, bytes_to_pop); + force = false; + ret = MODE_OK; + } else { + return ret; + } + } + + return ret; +} + +static void linser_process_delayed(struct work_struct *work) +{ + struct linser_priv *priv = container_of(work, struct linser_priv, + rx_work.work); + + linser_process_frame(priv, true); +} + +static ssize_t linser_receive_buf_fp(struct serdev_device *serdev, + const u8 *data, const u8 *fp, + size_t count) +{ + struct linser_priv *priv = serdev_device_get_drvdata(serdev); + enum linser_rx_status rx_status; + ssize_t n = 0; + int i; + + cancel_delayed_work_sync(&priv->rx_work); + + for (i = 0; i < count; i++) { + struct linser_rx rx; + + rx.data = data[i]; + rx.flag = (fp ? fp[i] : 0); + n += kfifo_in(&priv->rx_fifo, &rx, 1); + dev_dbg(&serdev->dev, "%s: n:%zd, flag:0x%02x, data:0x%02x\n", + __func__, n, rx.flag, data[i]); + } + + rx_status = linser_process_frame(priv, false); + + if (rx_status == NEED_FORCE) + schedule_delayed_work(&priv->rx_work, priv->force_timeout_jfs); + + return n; +} + +static const struct serdev_device_ops linser_ops = { + .receive_buf_fp = linser_receive_buf_fp, + .write_wakeup = serdev_device_write_wakeup, +}; + +static int linser_probe(struct serdev_device *serdev) +{ + struct linser_priv *priv; + int ret; + + priv = devm_kzalloc(&serdev->dev, sizeof(*priv), GFP_KERNEL); + if (!priv) + return -ENOMEM; + + ret = kfifo_alloc(&priv->rx_fifo, LINSER_RX_FIFO_SIZE, GFP_KERNEL); + if (ret) + return ret; + + INIT_DELAYED_WORK(&priv->rx_work, linser_process_delayed); + + priv->serdev = serdev; + serdev_device_set_drvdata(serdev, priv); + serdev_device_set_client_ops(serdev, &linser_ops); + + ret = serdev_device_open(serdev); + if (ret) { + dev_err(&serdev->dev, "Unable to open device\n"); + goto err_open; + } + + serdev_device_set_flow_control(serdev, false); + serdev_device_set_break_detection(serdev, true); + linser_derive_timings(priv, LIN_DEFAULT_BAUDRATE); + + mutex_init(&priv->resp_lock); + + priv->lin_dev = register_lin(&serdev->dev, &linser_lindev_ops); + if (IS_ERR_OR_NULL(priv->lin_dev)) { + ret = PTR_ERR(priv->lin_dev); + goto err_register_lin; + } + + return 0; + +err_register_lin: + serdev_device_close(serdev); +err_open: + kfifo_free(&priv->rx_fifo); + return ret; +} + +static void linser_remove(struct serdev_device *serdev) +{ + struct linser_priv *priv = serdev_device_get_drvdata(serdev); + + if (priv && priv->lin_dev) + unregister_lin(priv->lin_dev); + + serdev_device_close(serdev); +} + +static const struct of_device_id linser_of_match[] = { + { + .compatible = "linux,lin-serdev", + }, + {} +}; +MODULE_DEVICE_TABLE(of, linser_of_match); + +static struct serdev_device_driver linser_driver = { + .probe = linser_probe, + .remove = linser_remove, + .driver = { + .name = KBUILD_MODNAME, + .of_match_table = linser_of_match, + } +}; + +module_serdev_device_driver(linser_driver); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Christoph Fritz <christoph.fritz@xxxxxxxxx>"); +MODULE_DESCRIPTION("LIN-Bus serdev driver"); -- 2.39.2
