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linux/Documentation/ABI/stable/sysfs-driver-aspeed-vuart

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drivers/serial: Add driver for Aspeed virtual UART This change adds a driver for the 16550-based Aspeed virtual UART device. We use a similar process to the of_serial driver for device probe, but expose some VUART-specific functions through sysfs too. The VUART is two UART 'front ends' connected by their FIFO (no actual serial line in between). One is on the BMC side (management controller) and one is on the host CPU side. This driver is for the BMC side. The sysfs files allow the BMC userspace, which owns the system configuration policy, to specify at what IO port and interrupt number the host side will appear to the host on the Host <-> BMC LPC bus. It could be different on a different system (though most of them use 3f8/4). OpenPOWER host firmware doesn't like it when the host-side of the VUART's FIFO is not drained. This driver only disables host TX discard mode when the port is in use. We set the VUART enabled bit when we bind to the device, and clear it on unbind. We don't want to do this on open/release, as the host may be using this bit to configure serial output modes, which is independent of whether the devices has been opened by BMC userspace. Signed-off-by: Jeremy Kerr <jk@ozlabs.org> Signed-off-by: Joel Stanley <joel@jms.id.au> Acked-by: Rob Herring <robh@kernel.org> Reviewed-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-05-02 07:45:43 +00:00
What: /sys/bus/platform/drivers/aspeed-vuart/*/lpc_address
Date: April 2017
Contact: Jeremy Kerr <jk@ozlabs.org>
Description: Configures which IO port the host side of the UART
will appear on the host <-> BMC LPC bus.
Users: OpenBMC. Proposed changes should be mailed to
openbmc@lists.ozlabs.org
What: /sys/bus/platform/drivers/aspeed-vuart*/sirq
Date: April 2017
Contact: Jeremy Kerr <jk@ozlabs.org>
Description: Configures which interrupt number the host side of
the UART will appear on the host <-> BMC LPC bus.
Users: OpenBMC. Proposed changes should be mailed to
openbmc@lists.ozlabs.org
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