diff options
| -rw-r--r-- | Documentation/ABI/testing/sysfs-tty | 9 | ||||
| -rw-r--r-- | drivers/tty/serial/serial_core.c | 70 | ||||
| -rw-r--r-- | include/linux/serial_core.h | 3 |
3 files changed, 80 insertions, 2 deletions
diff --git a/Documentation/ABI/testing/sysfs-tty b/Documentation/ABI/testing/sysfs-tty index 9eb3c2b6b040..441105a75d1f 100644 --- a/Documentation/ABI/testing/sysfs-tty +++ b/Documentation/ABI/testing/sysfs-tty @@ -154,3 +154,12 @@ Description: device specification. For example, when user sets 7bytes on 16550A, which has 1/4/8/14 bytes trigger, the RX trigger is automatically changed to 4 bytes. + +What: /sys/class/tty/ttyS0/pps_4wire +Date: September 2018 +Contact: Steve Sakoman <steve@sakoman.com> +Description: + Shows/sets "4 wire" mode for the PPS input to the serial driver. + For fully implemented serial ports PPS is normally provided + on the DCD line. For partial "4 wire" implementations CTS is + used instead of DCD. diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c index 80bb56facfb6..ed0133395cc7 100644 --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -2664,6 +2664,57 @@ static ssize_t uart_get_attr_iomem_reg_shift(struct device *dev, return snprintf(buf, PAGE_SIZE, "%d\n", tmp.iomem_reg_shift); } +static ssize_t pps_4wire_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct tty_port *port = dev_get_drvdata(dev); + struct uart_state *state = container_of(port, struct uart_state, port); + struct uart_port *uport; + int mode = 0; + + mutex_lock(&port->mutex); + uport = uart_port_check(state); + if (!uport) + goto out; + + mode = uport->pps_4wire; + +out: + mutex_unlock(&port->mutex); + return sprintf(buf, mode ? "yes\n" : "no\n"); +} + +static ssize_t pps_4wire_store(struct device *dev, + struct device_attribute *attr, const char *buf, size_t count) +{ + struct tty_port *port = dev_get_drvdata(dev); + struct uart_state *state = container_of(port, struct uart_state, port); + struct uart_port *uport; + bool mode; + int ret; + + if (!count) + return -EINVAL; + + ret = kstrtobool(buf, &mode); + if (ret < 0) + return ret; + + mutex_lock(&port->mutex); + uport = uart_port_check(state); + if (!uport) + goto out; + + spin_lock_irq(&uport->lock); + uport->pps_4wire = mode; + spin_unlock_irq(&uport->lock); + +out: + mutex_unlock(&port->mutex); + return count; +} +static DEVICE_ATTR_RW(pps_4wire); + static DEVICE_ATTR(type, S_IRUSR | S_IRGRP, uart_get_attr_type, NULL); static DEVICE_ATTR(line, S_IRUSR | S_IRGRP, uart_get_attr_line, NULL); static DEVICE_ATTR(port, S_IRUSR | S_IRGRP, uart_get_attr_port, NULL); @@ -2692,6 +2743,7 @@ static struct attribute *tty_dev_attrs[] = { &dev_attr_io_type.attr, &dev_attr_iomem_base.attr, &dev_attr_iomem_reg_shift.attr, + &dev_attr_pps_4wire.attr, NULL, }; @@ -2748,6 +2800,9 @@ int uart_add_one_port(struct uart_driver *drv, struct uart_port *uport) goto out; } + /* assert that pps handling is done via DCD as default */ + uport->pps_4wire = 0; + /* * If this port is a console, then the spinlock is already * initialised. @@ -2923,7 +2978,7 @@ void uart_handle_dcd_change(struct uart_port *uport, unsigned int status) lockdep_assert_held_once(&uport->lock); - if (tty) { + if (tty && !uport->pps_4wire) { ld = tty_ldisc_ref(tty); if (ld) { if (ld->ops->dcd_change) @@ -2952,8 +3007,21 @@ EXPORT_SYMBOL_GPL(uart_handle_dcd_change); */ void uart_handle_cts_change(struct uart_port *uport, unsigned int status) { + struct tty_port *port = &uport->state->port; + struct tty_struct *tty = port->tty; + struct tty_ldisc *ld; + lockdep_assert_held_once(&uport->lock); + if (tty && uport->pps_4wire) { + ld = tty_ldisc_ref(tty); + if (ld) { + if (ld->ops->dcd_change) + ld->ops->dcd_change(tty, status); + tty_ldisc_deref(ld); + } + } + uport->icount.cts++; if (uart_softcts_mode(uport)) { diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h index 406edae44ca3..079793e5d3fa 100644 --- a/include/linux/serial_core.h +++ b/include/linux/serial_core.h @@ -255,7 +255,8 @@ struct uart_port { struct device *dev; /* parent device */ unsigned char hub6; /* this should be in the 8250 driver */ unsigned char suspended; - unsigned char unused[2]; + unsigned char pps_4wire; /* CTS instead of DCD */ + unsigned char unused; const char *name; /* port name */ struct attribute_group *attr_group; /* port specific attributes */ const struct attribute_group **tty_groups; /* all attributes (serial core use only) */ |