serial: 8250_pci: Add WCH CH352 quirk to avoid Xscale detection
The code in 8250.c for detecting ARM/XScale UARTs says: * Try writing and reading the UART_IER_UUE bit (b6). * If it works, this is probably one of the Xscale platform's * internal UARTs. If the above passes, it then goes on to: * It's an Xscale. * We'll leave the UART_IER_UUE bit set to 1 (enabled). However, the CH352 uses the UART_IER_UUE as the LOWPOWER function, so it is readable and writable. According to the datasheet: "LOWPOWER:When the bit is 1, close the internal benchmark clock of serial port to set into low-power status. So it essentially gets mis-detected as Xscale, and gets powered down in the process. The device in question where this was seen is listed by lspci as: Serial controller: Device 4348:3253 (rev 10) (prog-if 02 [16550]) Re-using the 353 quirk which just sets flags to fixed and type to 16550 is suitable for fixing the 352 as well. Signed-off-by: Wang YanQing <udknight@gmail.com> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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