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c73942e22a
If the DW_apb_uart is configured with UART_16550_COMPATIBLE configuration parameter set, then the Busy Functionality is not available. These UARTs will never generate the Busy detect indication interrupt, and therefore don't need handling for it. This creates a small optimization for the DW_apb_uarts configured without the busy functionality, but more importantly, it removes the small but real risk of hitting potential issues caused by busy functionality handling when no busy functionality exist. Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
77 lines
2.6 KiB
Plaintext
77 lines
2.6 KiB
Plaintext
* Synopsys DesignWare ABP UART
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Required properties:
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- compatible : "snps,dw-apb-uart"
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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 handling:
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The clock rate of the input clock needs to be supplied by one of
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- clock-frequency : the input clock frequency for the UART.
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- clocks : phandle to the input clock
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The supplying peripheral clock can also be handled, needing a second property
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- clock-names: tuple listing input clock names.
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Required elements: "baudclk", "apb_pclk"
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Optional properties:
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- snps,uart-16550-compatible : reflects the value of UART_16550_COMPATIBLE
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configuration parameter. Define this if your UART does not implement the busy
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functionality.
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- resets : phandle to the parent reset controller.
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- reg-shift : quantity to shift the register offsets by. If this property is
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not present then the register offsets are not shifted.
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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. If this property is not present then single byte
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accesses are used.
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- dcd-override : Override the DCD modem status signal. This signal will always
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be reported as active instead of being obtained from the modem status
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register. Define this if your serial port does not use this pin.
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- dsr-override : Override the DTS modem status signal. This signal will always
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be reported as active instead of being obtained from the modem status
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register. Define this if your serial port does not use this pin.
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- cts-override : Override the CTS modem status signal. This signal will always
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be reported as active instead of being obtained from the modem status
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register. Define this if your serial port does not use this pin.
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- ri-override : Override the RI modem status signal. This signal will always be
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reported as inactive instead of being obtained from the modem status register.
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Define this if your serial port does not use this pin.
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Example:
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uart@80230000 {
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compatible = "snps,dw-apb-uart";
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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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reg-io-width = <4>;
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dcd-override;
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dsr-override;
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cts-override;
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ri-override;
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};
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Example with one clock:
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uart@80230000 {
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compatible = "snps,dw-apb-uart";
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reg = <0x80230000 0x100>;
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clocks = <&baudclk>;
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interrupts = <10>;
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reg-shift = <2>;
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reg-io-width = <4>;
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};
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Example with two clocks:
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uart@80230000 {
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compatible = "snps,dw-apb-uart";
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reg = <0x80230000 0x100>;
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clocks = <&baudclk>, <&apb_pclk>;
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clock-names = "baudclk", "apb_pclk";
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interrupts = <10>;
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reg-shift = <2>;
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reg-io-width = <4>;
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};
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