lib: utils/serial: Add ARM PL011 UART driver - #17
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OpenSBI has no driver for the ARM PrimeCell PL011 UART, so platforms that expose a PL011 as their console (for example a QEMU RISC-V virt machine wired with an "arm,pl011" serial port) cannot use it as the firmware console. Add a polled MMIO PL011 driver modelled on the existing cadence-uart driver, together with an FDT glue driver matching "arm,pl011" and "arm,sbsa-uart", and wire it into the generic platform via a new FDT_SERIAL_PL011 / SERIAL_PL011 Kconfig pair enabled in the generic defconfig. The baud-rate divisors are only programmed when both the input clock frequency and the target baud rate are known; on platforms that do not expose "clock-frequency" (such as QEMU) the divisor registers are left untouched, matching the cadence-uart behaviour. The MMIO window is registered with the root domain so the console keeps working under domain isolation. Signed-off-by: Chen Pei <cp0613@linux.alibaba.com>
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OpenSBI has no driver for the ARM PrimeCell PL011 UART, so platforms that expose a PL011 as their console (for example a QEMU RISC-V virt machine wired with an "arm,pl011" serial port) cannot use it as the firmware console.
Add a polled MMIO PL011 driver modelled on the existing cadence-uart driver, together with an FDT glue driver matching "arm,pl011" and "arm,sbsa-uart", and wire it into the generic platform via a new FDT_SERIAL_PL011 / SERIAL_PL011 Kconfig pair enabled in the generic defconfig.
The baud-rate divisors are only programmed when both the input clock frequency and the target baud rate are known; on platforms that do not expose "clock-frequency" (such as QEMU) the divisor registers are left untouched, matching the cadence-uart behaviour. The MMIO window is registered with the root domain so the console keeps working under domain isolation.