[PATCH] ACPI CMOS region support rev. 4

[Anthony Jenkins]

On 03/16/2015 09:59 AM, Ian Smith wrote:
> On Sat, 14 Mar 2015 23:40:34 -0400, Anthony Jenkins wrote:
>
>  > How about this one? :-)  Sorry it's a week late.
>
> +static unsigned int atrtc_verbose = 0;
> +SYSCTL_UINT(_debug, OID_AUTO, atrtc_verbose, CTLFLAG_RWTUN,
> +       &atrtc_verbose, 0, "AT-RTC Debug Level (0-2)");
> +#define ATRTC_DBG_PRINTF(level, format, ...) \
> +       if (atrtc_verbose >= level) printf(format, ##__VA_ARGS__)
> +
>
> A sysctl is good, but it needs to default to 1 if we're ever going to 
> find out what various vendors are wanting to do with CMOS settings; 
> anyone annoyed by any extra messages outside boot or suspend/resume 
> could turn it off - after we've had the opportunity to get a report.

I'd actually prefer debug level to be compile-time (there's no real need
for it to be runtime), but I really don't want to add a config(5) knob
(I can of course).

> I can only reiterate part of my message before last, of March 2nd:
>
> =======
>> +static ACPI_STATUS
>> +acpi_rtc_cmos_handler(UINT32 function, ACPI_PHYSICAL_ADDRESS address,
>> +    UINT32 width, UINT64 *value, void *context, void *region_context)
>> +{
>> +    struct atrtc_softc *sc;
>> +
>> +    sc = (struct atrtc_softc *)context;
>> +    if (!value || !sc)
>> +            return AE_BAD_PARAMETER;
>> +    if (width > 32 || (width & 0x07) || address >= 64)
>> +            return AE_BAD_PARAMETER;
> Width 0 passes, and address 61 width 32 passes.  Maybe simpler:
>         int bytes;              /* or size, whatever, above */
>         bytes = width >> 3;

That should probably be

        bytes = (width + 7) >>3;

or

        bytes = (width + 7) / 8;    /* Integer division more expensive
on x86? */

because width == 1 would result in bytes = 0.

> and substitute 'bytes' subsequently, and here, perhaps:
>
>         if (bytes < 1 || bytes > 4 || (width & 0x07) || address > (64 - bytes))
>
>> +    if (!acpi_check_rtc_byteaccess(function == ACPI_READ, address))
>> +            return AE_BAD_PARAMETER;
> acpi_check_rtc_byteaccess() needs to be called per byte of 1, 2 or 4 
> bytes - or pass it 'bytes' also, and loop over each of them within?
> =======
>
> Otherwise (for example) a 2 byte read from 0x0b or 4 byte read from 
> 0x09-0x0b will read 0x0c (clearing interrupts), or a 2 or 4 byte write 
> to (say) 0x01 will also write to 0x02 and 0x04 (clobbering the time).

Right, this is an (incorrect) hybrid of a few attempts, probably from
around the time I lost my SSD and only had a single backup copy of my
work to go from.  In one revision I had disallowed all multibyte
accesses (width > 8) since IMHO it was more consistent/correct with the
suggested locking.  I wasn't ignoring your suggestion, just making one
or a few changes at a time (generally the simpler ones).

  I /believe/ the ACPI spec disallows requests for width=0.  Looking at
ACPIspec50.pdf, the smallest OperationRegion that can be defined is 1
byte, and the smallest Field within an OpRegion is 1 bit, and all
accesses to an OpRegion occur via Fields (Section 19.5.96
OperationRegion (Declare Operation Region)).  Doesn't hurt to check
tho.  Also OpRegions operations are synchronized, so I at least don't
have to worry about AML accessing CMOS all willy-nilly.

> Sorry if I'm too much of a stickler for defensive programming ..

Oh no problem, I can handle a bit of criticism :-)

Anthony

>
> cheers, Ian
>
>
> _______________________________________________
> freebsd-acpi at freebsd.org mailing list
> http://lists.freebsd.org/mailman/listinfo/freebsd-acpi
> To unsubscribe, send any mail to "freebsd-acpi-unsubscribe at freebsd.org"