On 02/01/2016 01:00 PM, Robin Murphy wrote:
So far, we have been blindly assuming that having access to a
memory-mapped timer frame implies that the individual elements of that
frame frame are already enabled. Whilst it's the firmware's job to give
us non-secure access to frames in the first place, we should not rely
on implementations always being generous enough to also configure CNTACR
for those non-secure frames (e.g. [1]).
Explicitly enable feature-level access per-frame, and verify that the
access we want is really implemented before trying to make use of it.
[1]:https://github.com/ARM-software/tf-issues/issues/170
Signed-off-by: Robin Murphy <[email protected]>
---
Hi Marc,
can you give your opinion on this patch ?
Thanks
-- Daniel
Changes from v1:
- Remove CNTACR_RFRQ check since the "no access, CNTFRQ reads as zero"
case can be handled the same way the driver deals with the "CNTFRQ
accessible, but not programmed" case.
- Reword the commit message to make more sense.
drivers/clocksource/arm_arch_timer.c | 36 ++++++++++++++++++++++++++++--------
1 file changed, 28 insertions(+), 8 deletions(-)
diff --git a/drivers/clocksource/arm_arch_timer.c
b/drivers/clocksource/arm_arch_timer.c
index c64d543..7c567f0 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -32,6 +32,14 @@
#define CNTTIDR 0x08
#define CNTTIDR_VIRT(n) (BIT(1) << ((n) * 4))
+#define CNTACR(n) (0x40 + ((n) * 4))
+#define CNTACR_RPCT BIT(0)
+#define CNTACR_RVCT BIT(1)
+#define CNTACR_RFRQ BIT(2)
+#define CNTACR_RVOFF BIT(3)
+#define CNTACR_RWVT BIT(4)
+#define CNTACR_RWPT BIT(5)
+
#define CNTVCT_LO 0x08
#define CNTVCT_HI 0x0c
#define CNTFRQ 0x10
@@ -757,7 +765,6 @@ static void __init arch_timer_mem_init(struct device_node
*np)
}
cnttidr = readl_relaxed(cntctlbase + CNTTIDR);
- iounmap(cntctlbase);
/*
* Try to find a virtual capable frame. Otherwise fall back to a
@@ -765,20 +772,31 @@ 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 ((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);
}
@@ -786,24 +804,26 @@ static void __init arch_timer_mem_init(struct device_node
*np)
base = arch_counter_base = of_iomap(best_frame, 0);
if (!base) {
pr_err("arch_timer: Can't map frame's registers\n");
- of_node_put(best_frame);
- return;
+ goto out;
}
if (arch_timer_mem_use_virtual)
irq = irq_of_parse_and_map(best_frame, 1);
else
irq = irq_of_parse_and_map(best_frame, 0);
- of_node_put(best_frame);
+
if (!irq) {
pr_err("arch_timer: Frame missing %s irq",
arch_timer_mem_use_virtual ? "virt" : "phys");
- return;
+ goto out;
}
arch_timer_detect_rate(base, np);
arch_timer_mem_register(base, irq);
arch_timer_common_init();
+out:
+ iounmap(cntctlbase);
+ of_node_put(best_frame);
}
CLOCKSOURCE_OF_DECLARE(armv7_arch_timer_mem, "arm,armv7-timer-mem",
arch_timer_mem_init);
--
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