| Message ID | 20160129183051.GO12841@codeaurora.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 29/01/16 18:30, Stephen Boyd wrote: > On 01/29, Robin Murphy wrote: >> So far, we have been blindly assuming that if a memory-mapped timer >> frame exists, then we have access to it. Whilst it's the firmware's >> job to give us non-secure access to frames in the first place, we >> should not rely on it always being generous enough to also configure >> CNTACR if it's not even using those frames itself. > > Hm, that first sentence is sort of misleading. We've been blindly > assuming that the firmware has configured CNTACR to have the > correct bits set for virtual/physical access. We've always relied > on status = "disabled" to figure out if we can access an entire > frame or not. Yeah, now that I read it back that sentence is nonsense for anything other than the very specific ideas of "frame" and "exists" that were passing through my head at some point last week - how about this instead? "So far, we have been blindly assuming that having access to a memory-mapped timer frame implies that the individual elements of that frame are already enabled." >> >> Explicitly enable feature-level access per-frame, and verify that the >> access we want is really implemented before trying to make use of it. >> >> Signed-off-by: Robin Murphy <robin.murphy@arm.com> >> --- >> drivers/clocksource/arm_arch_timer.c | 39 ++++++++++++++++++++++++++++-------- >> 1 file changed, 31 insertions(+), 8 deletions(-) >> >> diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c >> index c64d543..c88485d 100644 >> --- a/drivers/clocksource/arm_arch_timer.c >> +++ b/drivers/clocksource/arm_arch_timer.c >> @@ -765,20 +772,34 @@ static void __init arch_timer_mem_init(struct device_node *np) >> */ >> for_each_available_child_of_node(np, frame) { >> int n; >> + u32 cntacr; >> >> if (of_property_read_u32(frame, "frame-number", &n)) { >> pr_err("arch_timer: Missing frame-number\n"); >> - of_node_put(best_frame); >> of_node_put(frame); >> - return; >> + goto out; >> } >> >> - if (cnttidr & CNTTIDR_VIRT(n)) { >> + /* Try enabling everything, and see what sticks */ >> + cntacr = CNTACR_RFRQ | CNTACR_RWPT | CNTACR_RPCT | >> + CNTACR_RWVT | CNTACR_RVOFF | CNTACR_RVCT; >> + writel_relaxed(cntacr, cntctlbase + CNTACR(n)); >> + cntacr = readl_relaxed(cntctlbase + CNTACR(n)); >> + >> + if (~cntacr & CNTACR_RFRQ) >> + continue; > > Do we need this check? If we can't read the frequency we fall > back to looking for the DT property, so it shouldn't matter if we > can't read the hardware there. I was really just playing safe to start with. If we don't have cause to care about the difference between not having access vs. not having a frequency programmed then I'd agree it can probably go. >> + >> + if ((cnttidr & CNTTIDR_VIRT(n)) && >> + !(~cntacr & (CNTACR_RWVT | CNTACR_RVCT))) { >> of_node_put(best_frame); >> best_frame = frame; >> arch_timer_mem_use_virtual = true; >> break; >> } >> + >> + if (~cntacr & (CNTACR_RWPT | CNTACR_RPCT)) >> + continue; >> + >> of_node_put(best_frame); >> best_frame = of_node_get(frame); >> } > > Otherwise the patch looks fine and passes some light testing on > qcom devices. Great, thanks. The Trusted Firmware guys' warning shot has gone upstream already, if it helps: https://github.com/ARM-software/arm-trusted-firmware/commit/01fc3f7300e86b0b672977133c3028d638d0c672 > BTW, I'd like to add this patch on top so that we get some info > in /proc/iomem about which frame region is in use. It's about time I educated myself on what all the resource stuff really means, but superficially it seems reasonable, and it certainly makes the expected "2a830000-2a83ffff : arch_mem_timer" show up on my Juno. Thanks, Robin. > ---8<--- > From: Stephen Boyd <sboyd@codeaurora.org> > Subject: [PATCH] clocksource/arm_arch_timer: Map frame with > of_io_request_and_map() > > Let's use the of_io_request_and_map() API so that the frame > region is protected and shows up in /proc/iomem. > > Signed-off-by: Stephen Boyd <sboyd@codeaurora.org> > --- > drivers/clocksource/arm_arch_timer.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c > index c88485d489bf..59a08fd4f76a 100644 > --- a/drivers/clocksource/arm_arch_timer.c > +++ b/drivers/clocksource/arm_arch_timer.c > @@ -804,7 +804,8 @@ static void __init arch_timer_mem_init(struct device_node *np) > best_frame = of_node_get(frame); > } > > - base = arch_counter_base = of_iomap(best_frame, 0); > + base = arch_counter_base = of_io_request_and_map(best_frame, 0, > + "arch_mem_timer"); > if (!base) { > pr_err("arch_timer: Can't map frame's registers\n"); > goto out; >
On 01/29, Robin Murphy wrote: > On 29/01/16 18:30, Stephen Boyd wrote: > >On 01/29, Robin Murphy wrote: > >Hm, that first sentence is sort of misleading. We've been blindly > >assuming that the firmware has configured CNTACR to have the > >correct bits set for virtual/physical access. We've always relied > >on status = "disabled" to figure out if we can access an entire > >frame or not. > > Yeah, now that I read it back that sentence is nonsense for anything > other than the very specific ideas of "frame" and "exists" that were > passing through my head at some point last week - how about this > instead? > > "So far, we have been blindly assuming that having access to a > memory-mapped timer frame implies that the individual elements of > that frame are already enabled." Sounds good. > > >> > >>Explicitly enable feature-level access per-frame, and verify that the > >>access we want is really implemented before trying to make use of it. > >> > >>Signed-off-by: Robin Murphy <robin.murphy@arm.com> > >>--- > >> drivers/clocksource/arm_arch_timer.c | 39 ++++++++++++++++++++++++++++-------- > >> 1 file changed, 31 insertions(+), 8 deletions(-) > >> > >>diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c > >>index c64d543..c88485d 100644 > >>--- a/drivers/clocksource/arm_arch_timer.c > >>+++ b/drivers/clocksource/arm_arch_timer.c > >>@@ -765,20 +772,34 @@ static void __init arch_timer_mem_init(struct device_node *np) > >> */ > >> for_each_available_child_of_node(np, frame) { > >> int n; > >>+ u32 cntacr; > >> > >> if (of_property_read_u32(frame, "frame-number", &n)) { > >> pr_err("arch_timer: Missing frame-number\n"); > >>- of_node_put(best_frame); > >> of_node_put(frame); > >>- return; > >>+ goto out; > >> } > >> > >>- if (cnttidr & CNTTIDR_VIRT(n)) { > >>+ /* Try enabling everything, and see what sticks */ > >>+ cntacr = CNTACR_RFRQ | CNTACR_RWPT | CNTACR_RPCT | > >>+ CNTACR_RWVT | CNTACR_RVOFF | CNTACR_RVCT; > >>+ writel_relaxed(cntacr, cntctlbase + CNTACR(n)); > >>+ cntacr = readl_relaxed(cntctlbase + CNTACR(n)); > >>+ > >>+ if (~cntacr & CNTACR_RFRQ) > >>+ continue; > > > >Do we need this check? If we can't read the frequency we fall > >back to looking for the DT property, so it shouldn't matter if we > >can't read the hardware there. > > I was really just playing safe to start with. If we don't have cause > to care about the difference between not having access vs. not > having a frequency programmed then I'd agree it can probably go. > Yeah I'm mostly worried that we'll break something somewhere because that bit doesn't stick and it's the only frame we can use. Or we can give it a shot and then remove clock-frequency from the dts binding for mmio timers. > > Great, thanks. The Trusted Firmware guys' warning shot has gone > upstream already, if it helps: > > https://github.com/ARM-software/arm-trusted-firmware/commit/01fc3f7300e86b0b672977133c3028d638d0c672 Ah I see. It would be nice if that bug gave a reason why it should be done, instead of just saying it must be this way. O well.
diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c index c88485d489bf..59a08fd4f76a 100644 --- a/drivers/clocksource/arm_arch_timer.c +++ b/drivers/clocksource/arm_arch_timer.c @@ -804,7 +804,8 @@ static void __init arch_timer_mem_init(struct device_node *np) best_frame = of_node_get(frame); } - base = arch_counter_base = of_iomap(best_frame, 0); + base = arch_counter_base = of_io_request_and_map(best_frame, 0, + "arch_mem_timer"); if (!base) { pr_err("arch_timer: Can't map frame's registers\n"); goto out;