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06aa82e498
8250 uart driver currently supports only software assisted hw flow control. The software assisted hw flow control maintains a hw_stopped flag in the tty structure to stop and start transmission and use modem status interrupt for the event to drive the handshake signals. This is not needed if hw has flow control capabilities. This patch adds a DT attribute for enabling hw flow control for a uart port. Also skip stop and start if this flag is present in flag field of the port structure. Signed-off-by: Murali Karicheri <m-karicheri2@ti.com> CC: Rob Herring <robh+dt@kernel.org> CC: Pawel Moll <pawel.moll@arm.com> CC: Mark Rutland <mark.rutland@arm.com> CC: Ian Campbell <ijc+devicetree@hellion.org.uk> CC: Kumar Gala <galak@codeaurora.org> CC: Randy Dunlap <rdunlap@infradead.org> CC: Jiri Slaby <jslaby@suse.cz> CC: Santosh Shilimkar <santosh.shilimkar@ti.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
51 lines
1.6 KiB
Plaintext
51 lines
1.6 KiB
Plaintext
* UART (Universal Asynchronous Receiver/Transmitter)
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Required properties:
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- compatible : one of:
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- "ns8250"
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- "ns16450"
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- "ns16550a"
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- "ns16550"
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- "ns16750"
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- "ns16850"
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- "nvidia,tegra20-uart"
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- "nxp,lpc3220-uart"
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- "ibm,qpace-nwp-serial"
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- "altr,16550-FIFO32"
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- "altr,16550-FIFO64"
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- "altr,16550-FIFO128"
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- "serial" if the port type is unknown.
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- reg : offset and length of the register set for the device.
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- interrupts : should contain uart interrupt.
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- clock-frequency : the input clock frequency for the UART
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or
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clocks phandle to refer to the clk used as per Documentation/devicetree
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/bindings/clock/clock-bindings.txt
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Optional properties:
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- current-speed : the current active speed of the UART.
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- reg-offset : offset to apply to the mapbase from the start of the registers.
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- reg-shift : quantity to shift the register offsets by.
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- reg-io-width : the size (in bytes) of the IO accesses that should be
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performed on the device. There are some systems that require 32-bit
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accesses to the UART (e.g. TI davinci).
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- used-by-rtas : set to indicate that the port is in use by the OpenFirmware
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RTAS and should not be registered.
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- no-loopback-test: set to indicate that the port does not implements loopback
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test mode
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- fifo-size: the fifo size of the UART.
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- auto-flow-control: one way to enable automatic flow control support. The
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driver is allowed to detect support for the capability even without this
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property.
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- has-hw-flow-control: the hardware has flow control capability.
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Example:
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uart@80230000 {
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compatible = "ns8250";
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reg = <0x80230000 0x100>;
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clock-frequency = <3686400>;
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interrupts = <10>;
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reg-shift = <2>;
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};
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