On Tue, Sep 17, 2024 at 06:10:25AM -0700, Palmer Dabbelt wrote: > On Mon, 29 Jul 2024 22:12:18 PDT (-0700), Sunil V L wrote: > > Currently, 8250_platform driver is used only for devices with fixed > > serial ports (plat_serial8250_port). Extend this driver for any generic > > 16550A platform devices which can be probed using standard hardware > > discovery mechanisms like ACPI. > > > > This is required in particular for RISC-V which has non-PNP generic > > 16550A compatible UART that needs to be enumerated as ACPI platform > > device. > It seems a bit awkward that we need something RISC-V specific here. I > guess the idea is that we don't want to depend on PNP because we'd end > up with a bunch of PCI dependencies as well? That seems like kind of an > odd way to do things, but I'm frequently suprised by ACPI stuff so We have the same for HSUART on Intel (see 8250_dw.c). The ACPI devices use different approach than PNP. PNP has the exact requirements for compatibility with the legacy UARTs (to some extend). It puts some limitations. I believe having specifics for RISC-V is fine. But I haven't checked the real IP used in the SoC. If it's one that we have the existing driver for (like again mentioned 8250_dw.c), then it should be added there. TL;DR: so, what is the IP is in hardware for UART? Custom? -- With Best Regards, Andy Shevchenko
