diff options
| -rw-r--r-- | Documentation/ABI/testing/sysfs-tty | 7 | ||||
| -rw-r--r-- | drivers/tty/serial/serial_core.c | 60 |
2 files changed, 63 insertions, 4 deletions
diff --git a/Documentation/ABI/testing/sysfs-tty b/Documentation/ABI/testing/sysfs-tty index 9eb3c2b6b040..e157130a6792 100644 --- a/Documentation/ABI/testing/sysfs-tty +++ b/Documentation/ABI/testing/sysfs-tty @@ -154,3 +154,10 @@ 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/console +Date: February 2020 +Contact: Andy Shevchenko <andriy.shevchenko@linux.intel.com> +Description: + Allows user to detach or attach back the given device as + kernel console. It shows and accepts a boolean variable. diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c index 38ef6afddce8..66a5e2faf57e 100644 --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -1922,7 +1922,7 @@ static inline bool uart_console_enabled(struct uart_port *port) */ static inline void uart_port_spin_lock_init(struct uart_port *port) { - if (uart_console_enabled(port)) + if (uart_console(port)) return; spin_lock_init(&port->lock); @@ -2751,6 +2751,56 @@ static ssize_t iomem_reg_shift_show(struct device *dev, return snprintf(buf, PAGE_SIZE, "%d\n", tmp.iomem_reg_shift); } +static ssize_t console_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; + bool console = false; + + mutex_lock(&port->mutex); + uport = uart_port_check(state); + if (uport) + console = uart_console_enabled(uport); + mutex_unlock(&port->mutex); + + return sprintf(buf, "%c\n", console ? 'Y' : 'N'); +} + +static ssize_t console_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 oldconsole, newconsole; + int ret; + + ret = kstrtobool(buf, &newconsole); + if (ret) + return ret; + + mutex_lock(&port->mutex); + uport = uart_port_check(state); + if (uport) { + oldconsole = uart_console_enabled(uport); + if (oldconsole && !newconsole) { + ret = unregister_console(uport->cons); + } else if (!oldconsole && newconsole) { + if (uart_console(uport)) + register_console(uport->cons); + else + ret = -ENOENT; + } + } else { + ret = -ENXIO; + } + mutex_unlock(&port->mutex); + + return ret < 0 ? ret : count; +} + static DEVICE_ATTR_RO(uartclk); static DEVICE_ATTR_RO(type); static DEVICE_ATTR_RO(line); @@ -2764,6 +2814,7 @@ static DEVICE_ATTR_RO(custom_divisor); static DEVICE_ATTR_RO(io_type); static DEVICE_ATTR_RO(iomem_base); static DEVICE_ATTR_RO(iomem_reg_shift); +static DEVICE_ATTR_RW(console); static struct attribute *tty_dev_attrs[] = { &dev_attr_uartclk.attr, @@ -2779,12 +2830,13 @@ static struct attribute *tty_dev_attrs[] = { &dev_attr_io_type.attr, &dev_attr_iomem_base.attr, &dev_attr_iomem_reg_shift.attr, - NULL, - }; + &dev_attr_console.attr, + NULL +}; static const struct attribute_group tty_dev_attr_group = { .attrs = tty_dev_attrs, - }; +}; /** * uart_add_one_port - attach a driver-defined port structure |