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.
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 <[email protected]> --- 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 @@ -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 +772,34 @@ 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; + + 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 +807,26 @@ 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); -- 2.7.0.25.gfc10eb5.dirty
