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Revert "serial:serial_core: Allow use of CTS for PPS line discipline"

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This reverts commit c550f01c81.

Turns out the samsung tty driver is mucking around in the "unused" port
fields and this patch breaks that code :(

So we need to fix that driver up before this can be accepted.

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Steve Sakoman <steve@sakoman.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Greg Kroah-Hartman 2018-10-04 09:57:23 -07:00
parent aad2d4952d
commit 817e9bc8cc
3 changed files with 2 additions and 80 deletions
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9
Documentation/ABI/testing/sysfs-tty
View File

@ -154,12 +154,3 @@ 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.

70
drivers/tty/serial/serial_core.c
View File

@ -2724,57 +2724,6 @@ 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);
@ -2803,7 +2752,6 @@ 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,
};
@ -2860,9 +2808,6 @@ 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.
@ -3038,7 +2983,7 @@ void uart_handle_dcd_change(struct uart_port *uport, unsigned int status)
lockdep_assert_held_once(&uport->lock);
if (tty && !uport->pps_4wire) {
if (tty) {
ld = tty_ldisc_ref(tty);
if (ld) {
if (ld->ops->dcd_change)
@ -3067,21 +3012,8 @@ 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)) {

3
include/linux/serial_core.h
View File

@ -257,8 +257,7 @@ struct uart_port {
struct device *dev; /* parent device */
unsigned char hub6; /* this should be in the 8250 driver */
unsigned char suspended;
unsigned char pps_4wire; /* CTS instead of DCD */
unsigned char unused;
unsigned char unused[2];
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) */