Hi Arnd, On 16/01/15 17:31, Arnd Bergmann wrote: > On Friday 16 January 2015 17:22:56 Andre Przywara wrote: >> The ARM Server Base System Architecture[1] document describes a >> generic UART which is a subset of the PL011 UART. >> It lacks DMA support, baud rate control and modem status line >> control, among other things. >> The idea is to move the UART initialization and setup into the >> firmware (which does this job today already) and let the kernel just >> use the UART for sending and receiving characters. > > Given that all other approaches that have been tried have failed, this > seems like the best way forward. I don't know enough about the driver > to do a detailed review, but all patches looked good to me as far as > I could tell. Thanks for looking at them! > One question: How does the name space and minor number allocation work > if you have both sbsa-uart and real pl011 in the same system? Do > they share the ttyAMA name space without collisions? Yes, that works. Both parts use the same pl011_probe_dt_alias() routine to do the numbering. For testing I specified the second and fourth port as SBSA in the DT, leaving the first and third as PL011. This is what you get then: ... Serial: AMBA PL011 UART driver uart-pl011 1c090000.uart: ttyAMA0 at MMIO 0x1c090000 (irq = 15, base_baud = 0) is a PL011 rev2 ... uart-pl011 1c0b0000.uart: ttyAMA2 at MMIO 0x1c0b0000 (irq = 17, base_baud = 0) is a PL011 rev2 .... sbsa-uart 1c0a0000.uart: ttyAMA1 at MMIO 0x1c0a0000 (irq = 16, base_baud = 0) is a SBSA sbsa-uart 1c0c0000.uart: ttyAMA3 at MMIO 0x1c0c0000 (irq = 18, base_baud = 0) is a SBSA Cheers, Andre. -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
