Date: Sun, 3 Nov 2019 13:01:18 +0100 From: Milan Obuch <freebsd-hackers@dino.sk> To: Oleksandr Tymoshenko <gonzo@bluezbox.com> Cc: freebsd-hackers@freebsd.org, Oliver Pinter <oliver.pinter@hardenedbsd.org> Subject: Re: UART driver as kld - how? Message-ID: <20191103130118.36fa6eec@zeta.dino.sk> In-Reply-To: <20191103042321.GA49790@bluezbox.com> References: <20191027214209.712d62ca@zeta.dino.sk> <CAPQ4ffuoHRFghwo=okFoNVHw9TYdwFw_wgUxa5_rm6FqjsNVsg@mail.gmail.com> <20191027232956.28b11772@zeta.dino.sk> <20191028191005.GA89835@bluezbox.com> <20191028201952.20a92307@zeta.dino.sk> <20191102214100.500ba493@zeta.dino.sk> <20191103042321.GA49790@bluezbox.com>
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On Sat, 2 Nov 2019 21:23:21 -0700 Oleksandr Tymoshenko <gonzo@bluezbox.com> wrote: > Milan Obuch (freebsd-hackers@dino.sk) wrote: [ snip ] > > After studying other uart_dev_xxx.c files I am able to create > > working skeleton uart driver. I can compile it, kldload, and get > > some console output. Right now, I hit another problem - uart > > framework is not documented well, at least no man page is found in > > share/man directory. > > > > My probe function is similar to that in uart_dev_snps.c file, > > simplified, and I need to know what arguments should uart_bus_probe > > function be invoked with. In many device drivers there are mostly > > zeros, but this does not work for me. > > > > Currently I am getting error 6, ENXIO, so I am not correctly > > attaching my driver to device. Putting some printf here and there, > > I found test at line 508, file uart_core.c, fails - sc->sc_class is > > null. Question is, now, where and how should this field in this > > structure be initialized... > > > > I am sure I need docs/description for other functions as well, so if > > anybody knows where good uart framework description could be found, > > please advice. Or if somebody already has good understanding of it > > and could help me with my issues, it wil be greatly appreciated. > > if you follow uart_dev_snsps.c template, the sc_class is set in > probe function: > > uart_class = (struct uart_class > *)ofw_bus_search_compatible(dev, compat_data)->ocd_data; > if (uart_class == NULL) > return (ENXIO); > > freq = 0; > sc = device_get_softc(dev); > sc->ns8250.base.sc_class = uart_class; > *facepalm* I totally overlooked the obvious... yes, you are right. [ snip ] > In your case, my guess would be: you either do not set the sc_class > member var in probe function or your base var is not the first in the > struct. > Back to testing... probe function now does work, so I am going to analyze what should be done in attach... and why I am getting now panic... I'll write again when I find another obstacle I do not understand or I have working driver, whatever comes first :) Regards, Milan
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