On Thu, 2 May 2024, Christoph Fritz wrote: > 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 | 500 +++++++++++++++++++++++++++++++++++ > 3 files changed, 517 insertions(+) > create mode 100644 drivers/net/can/lin-serdev.c > > diff --git a/drivers/net/can/Kconfig b/drivers/net/can/Kconfig > index 0934bbf8d03b2..91c6cdeefe440 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 serial 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..13fd9a54c6c93 > --- /dev/null > +++ b/drivers/net/can/lin-serdev.c > @@ -0,0 +1,500 @@ > +// SPDX-License-Identifier: GPL-2.0+ > +/* Copyright (C) 2024 hexDEV GmbH - https://hexdev.de */ > + > +#include <linux/delay.h> > +#include <linux/init.h> > +#include <linux/kfifo.h> > +#include <linux/module.h> > +#include <linux/of.h> > +#include <linux/serdev.h> > +#include <linux/slab.h> > +#include <linux/tty.h> > +#include <net/lin.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; > + unsigned long break_usleep_min; > + unsigned long break_usleep_max; > + unsigned long post_break_usleep_min; > + unsigned long post_break_usleep_max; > + unsigned long force_timeout_jfs; > + struct lin_responder_answer respond_answ[LIN_NUM_IDS]; > + struct mutex resp_lock; /* protects respond_answ */ > + bool is_stopped; > +}; > + > +static int linser_open(struct lin_device *ldev) > +{ > + struct serdev_device *serdev = to_serdev_device(ldev->dev); > + struct linser_priv *priv = serdev_device_get_drvdata(serdev); > + int ret; > + > + if (priv->is_stopped) { > + ret = serdev_device_open(serdev); > + if (ret) { > + dev_err(&serdev->dev, "Unable to open device\n"); > + return ret; > + } > + > + serdev_device_set_flow_control(serdev, false); > + serdev_device_set_break_detection(serdev, true); > + > + priv->is_stopped = false; > + } > + > + return 0; > +} > + > +static int linser_stop(struct lin_device *ldev) > +{ > + struct serdev_device *serdev = to_serdev_device(ldev->dev); > + struct linser_priv *priv = serdev_device_get_drvdata(serdev); > + > + if (priv->is_stopped) > + return 0; > + > + serdev_device_close(serdev); > + priv->is_stopped = true; > + > + 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 = (USEC_PER_SEC * LINSER_SAMPLES_PER_CHAR) / > + break_baud; > + priv->break_usleep_max = priv->break_usleep_min + 50; > + priv->post_break_usleep_min = (USEC_PER_SEC * 1 /* 1 bit */) / break_baud; Don't mix comments and code like this. > + priv->post_break_usleep_max = priv->post_break_usleep_min + 30; > + > + timeout_us = DIV_ROUND_CLOSEST(USEC_PER_SEC * 256 /* bit */, bitrate); Ditto. > + 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; > + int ret; > + > + ret = linser_open(ldev); > + if (ret) > + return ret; > + > + speed = serdev_device_set_baudrate(serdev, bitrate); > + if (!bitrate || speed != bitrate) > + return -EINVAL; > + > + linser_derive_timings(priv, bitrate); > + > + return 0; > +} > + > +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); guard(mutex)(&priv->resp_lock); > + memcpy(answ, r, sizeof(struct lin_responder_answer)); sizeof(*answ); > + 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)); Ditto. > + 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 struct lin_device_ops linser_lindev_ops = { > + .ldo_open = linser_open, > + .ldo_stop = linser_stop, > + .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); scoped_guard() can be used here. > + > + if (!answ->is_active) { > + mutex_unlock(&priv->resp_lock); > + return 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 { > + mutex_unlock(&priv->resp_lock); > + return false; Use reverse logic so you can reduce indent. > + } > + } 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; > +} > + > +static void linser_pop_fifo(struct linser_priv *priv, size_t n) > +{ > + for (size_t i = 0; i < n; i++) > + kfifo_skip(&priv->rx_fifo); > +} > + > +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]; > + unsigned int count, i, brk = 0; > + > + count = kfifo_out_peek(&priv->rx_fifo, buf, LINSER_PARSE_BUFFER); > + > + 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; Reverse logic & deindent the main block. > + } > + } > + > + 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; > + } > + > + serdev_device_close(serdev); > + priv->is_stopped = true; > + > + 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); > + > + unregister_lin(priv->lin_dev); > +} > + > +static const struct of_device_id linser_of_match[] = { > + { > + .compatible = "hexdev,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"); > -- i.
