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In the future we would like to disable power management on the serial devices used as kernel consoles to avoid weird behaviour in some cases. However, disabling PM may prevent system to go to deep sleep states, which in its turn leads to the higher power consumption. Tony Lindgren proposed a work around, i.e. allow user to detach such consoles to make PM working again. In case user wants to see what's going on, it also provides a mechanism to attach console back. Link: https://lists.openwall.net/linux-kernel/2018/09/29/65 Suggested-by: Tony Lindgren <tony@atomide.com> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Link: https://lore.kernel.org/r/20200217114016.49856-3-andriy.shevchenko@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
164 lines
4.9 KiB
Plaintext
164 lines
4.9 KiB
Plaintext
What: /sys/class/tty/console/active
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Date: Nov 2010
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Contact: Kay Sievers <kay.sievers@vrfy.org>
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Description:
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Shows the list of currently configured
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console devices, like 'tty1 ttyS0'.
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The last entry in the file is the active
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device connected to /dev/console.
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The file supports poll() to detect virtual
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console switches.
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What: /sys/class/tty/tty0/active
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Date: Nov 2010
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Contact: Kay Sievers <kay.sievers@vrfy.org>
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Description:
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Shows the currently active virtual console
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device, like 'tty1'.
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The file supports poll() to detect virtual
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console switches.
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What: /sys/class/tty/ttyS0/uartclk
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Date: Sep 2012
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Contact: Tomas Hlavacek <tmshlvck@gmail.com>
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Description:
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Shows the current uartclk value associated with the
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UART port in serial_core, that is bound to TTY like ttyS0.
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uartclk = 16 * baud_base
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These sysfs values expose the TIOCGSERIAL interface via
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sysfs rather than via ioctls.
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What: /sys/class/tty/ttyS0/type
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Date: October 2012
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Contact: Alan Cox <alan@linux.intel.com>
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Description:
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Shows the current tty type for this port.
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These sysfs values expose the TIOCGSERIAL interface via
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sysfs rather than via ioctls.
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What: /sys/class/tty/ttyS0/line
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Date: October 2012
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Contact: Alan Cox <alan@linux.intel.com>
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Description:
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Shows the current tty line number for this port.
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These sysfs values expose the TIOCGSERIAL interface via
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sysfs rather than via ioctls.
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What: /sys/class/tty/ttyS0/port
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Date: October 2012
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Contact: Alan Cox <alan@linux.intel.com>
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Description:
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Shows the current tty port I/O address for this port.
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These sysfs values expose the TIOCGSERIAL interface via
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sysfs rather than via ioctls.
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What: /sys/class/tty/ttyS0/irq
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Date: October 2012
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Contact: Alan Cox <alan@linux.intel.com>
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Description:
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Shows the current primary interrupt for this port.
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These sysfs values expose the TIOCGSERIAL interface via
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sysfs rather than via ioctls.
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What: /sys/class/tty/ttyS0/flags
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Date: October 2012
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Contact: Alan Cox <alan@linux.intel.com>
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Description:
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Show the tty port status flags for this port.
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These sysfs values expose the TIOCGSERIAL interface via
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sysfs rather than via ioctls.
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What: /sys/class/tty/ttyS0/xmit_fifo_size
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Date: October 2012
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Contact: Alan Cox <alan@linux.intel.com>
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Description:
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Show the transmit FIFO size for this port.
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These sysfs values expose the TIOCGSERIAL interface via
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sysfs rather than via ioctls.
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What: /sys/class/tty/ttyS0/close_delay
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Date: October 2012
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Contact: Alan Cox <alan@linux.intel.com>
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Description:
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Show the closing delay time for this port in ms.
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These sysfs values expose the TIOCGSERIAL interface via
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sysfs rather than via ioctls.
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What: /sys/class/tty/ttyS0/closing_wait
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Date: October 2012
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Contact: Alan Cox <alan@linux.intel.com>
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Description:
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Show the close wait time for this port in ms.
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These sysfs values expose the TIOCGSERIAL interface via
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sysfs rather than via ioctls.
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What: /sys/class/tty/ttyS0/custom_divisor
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Date: October 2012
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Contact: Alan Cox <alan@linux.intel.com>
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Description:
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Show the custom divisor if any that is set on this port.
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These sysfs values expose the TIOCGSERIAL interface via
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sysfs rather than via ioctls.
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What: /sys/class/tty/ttyS0/io_type
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Date: October 2012
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Contact: Alan Cox <alan@linux.intel.com>
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Description:
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Show the I/O type that is to be used with the iomem base
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address.
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These sysfs values expose the TIOCGSERIAL interface via
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sysfs rather than via ioctls.
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What: /sys/class/tty/ttyS0/iomem_base
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Date: October 2012
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Contact: Alan Cox <alan@linux.intel.com>
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Description:
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The I/O memory base for this port.
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These sysfs values expose the TIOCGSERIAL interface via
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sysfs rather than via ioctls.
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What: /sys/class/tty/ttyS0/iomem_reg_shift
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Date: October 2012
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Contact: Alan Cox <alan@linux.intel.com>
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Description:
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Show the register shift indicating the spacing to be used
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for accesses on this iomem address.
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These sysfs values expose the TIOCGSERIAL interface via
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sysfs rather than via ioctls.
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What: /sys/class/tty/ttyS0/rx_trig_bytes
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Date: May 2014
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Contact: Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com>
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Description:
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Shows current RX interrupt trigger bytes or sets the
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user specified value to change it for the FIFO buffer.
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Users can show or set this value regardless of opening the
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serial device file or not.
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The RX trigger can be set one of four kinds of values for UART
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serials. When users input a meaning less value to this I/F,
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the RX trigger is changed to the nearest lower value for the
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device specification. For example, when user sets 7bytes on
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16550A, which has 1/4/8/14 bytes trigger, the RX trigger is
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automatically changed to 4 bytes.
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What: /sys/class/tty/ttyS0/console
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Date: February 2020
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Contact: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
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Description:
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Allows user to detach or attach back the given device as
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kernel console. It shows and accepts a boolean variable.
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