| Message ID | 20240508141333.44610-1-philmd@linaro.org |
|---|---|
| State | New |
| Headers | show |
| Series | hw/clock: Expose 'freq-hz' QOM property | expand |
On Wed, 8 May 2024 at 15:13, Philippe Mathieu-Daudé <philmd@linaro.org> wrote: > > Expose the clock frequency via the QOM 'freq-hz' property, > as it might be useful for QTests. > > HMP example: > > $ qemu-system-mips -S -monitor stdio -M mipssim > (qemu) qom-get /machine/cpu-refclk freq-hz > 12000000 > > Inspired-by: Inès Varhol <ines.varhol@telecom-paris.fr> > Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org> So I have a couple of thoughts here: (1) if this is intended for qtests, would exposing the period (i.e. QOM equivalent of clock_get() rather than clock_get_hz()) be better? A Hz figure has rounding so it's not as accurate. (2) We should document this in clocks.rst; I guess we want to say "only intended for use in qtests" (i.e. if you're part of QEMU use the existing function interface, not this). thanks -- PMM
On 8/5/24 19:46, Peter Maydell wrote: > On Wed, 8 May 2024 at 15:13, Philippe Mathieu-Daudé <philmd@linaro.org> wrote: >> >> Expose the clock frequency via the QOM 'freq-hz' property, >> as it might be useful for QTests. >> >> HMP example: >> >> $ qemu-system-mips -S -monitor stdio -M mipssim >> (qemu) qom-get /machine/cpu-refclk freq-hz >> 12000000 >> >> Inspired-by: Inès Varhol <ines.varhol@telecom-paris.fr> >> Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org> > > So I have a couple of thoughts here: > > (1) if this is intended for qtests, would exposing the period (i.e. > QOM equivalent of clock_get() rather than clock_get_hz()) be better? > A Hz figure has rounding so it's not as accurate. Indeed, simpler to compare from QTest perspective. > (2) We should document this in clocks.rst; I guess we want to say > "only intended for use in qtests" (i.e. if you're part of QEMU > use the existing function interface, not this). OK, and we can also only expose this for QTest using: if (qtest_enabled()) { object_property_add(obj, "[qtest-]clock-period", ...); }
On Wed, 8 May 2024 at 22:27, Philippe Mathieu-Daudé <philmd@linaro.org> wrote: > > On 8/5/24 19:46, Peter Maydell wrote: > > On Wed, 8 May 2024 at 15:13, Philippe Mathieu-Daudé <philmd@linaro.org> wrote: > >> > >> Expose the clock frequency via the QOM 'freq-hz' property, > >> as it might be useful for QTests. > >> > >> HMP example: > >> > >> $ qemu-system-mips -S -monitor stdio -M mipssim > >> (qemu) qom-get /machine/cpu-refclk freq-hz > >> 12000000 > >> > >> Inspired-by: Inès Varhol <ines.varhol@telecom-paris.fr> > >> Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org> > > > > So I have a couple of thoughts here: > > > > (1) if this is intended for qtests, would exposing the period (i.e. > > QOM equivalent of clock_get() rather than clock_get_hz()) be better? > > A Hz figure has rounding so it's not as accurate. > > Indeed, simpler to compare from QTest perspective. > > > (2) We should document this in clocks.rst; I guess we want to say > > "only intended for use in qtests" (i.e. if you're part of QEMU > > use the existing function interface, not this). > > OK, and we can also only expose this for QTest using: > > if (qtest_enabled()) { > object_property_add(obj, "[qtest-]clock-period", ...); > } Yes, that seems reasonable. (I don't know if we have any other qtest-only properties but I don't see any reason why we shouldn't have them if we want to expose stuff for tests only.) thanks -- PMM
diff --git a/hw/core/clock.c b/hw/core/clock.c index e212865307..55f86ef483 100644 --- a/hw/core/clock.c +++ b/hw/core/clock.c @@ -13,6 +13,7 @@ #include "qemu/osdep.h" #include "qemu/cutils.h" +#include "qapi/visitor.h" #include "hw/clock.h" #include "trace.h" @@ -158,6 +159,14 @@ bool clock_set_mul_div(Clock *clk, uint32_t multiplier, uint32_t divider) return true; } +static void clock_prop_freq_get(Object *obj, Visitor *v, const char *name, + void *opaque, Error **errp) +{ + Clock *clk = CLOCK(obj); + uint64_t freq_hz = clock_get_hz(clk); + visit_type_uint64(v, name, &freq_hz, errp); +} + static void clock_initfn(Object *obj) { Clock *clk = CLOCK(obj); @@ -166,6 +175,9 @@ static void clock_initfn(Object *obj) clk->divider = 1; QLIST_INIT(&clk->children); + + object_property_add(obj, "freq-hz", "uint64", + clock_prop_freq_get, NULL, NULL, NULL); } static void clock_finalizefn(Object *obj)
Expose the clock frequency via the QOM 'freq-hz' property, as it might be useful for QTests. HMP example: $ qemu-system-mips -S -monitor stdio -M mipssim (qemu) qom-get /machine/cpu-refclk freq-hz 12000000 Inspired-by: Inès Varhol <ines.varhol@telecom-paris.fr> Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org> --- hw/core/clock.c | 12 ++++++++++++ 1 file changed, 12 insertions(+)