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Commit e392d603 authored by Robin Murphy's avatar Robin Murphy Committed by Daniel Lezcano
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clocksource/drivers/arm_arch_timer: Enable and verify MMIO access 

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



Acked-by: default avatarMark Rutland <mark.rutland@arm.com>
Reviewed-by: default avatarStephen Boyd <sboyd@codeaurora.org>
Tested-by: default avatarStephen Boyd <sboyd@codeaurora.org>
Acked-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: default avatarRobin Murphy <robin.murphy@arm.com>
Signed-off-by: default avatarDaniel Lezcano <daniel.lezcano@linaro.org>
parent bbf66d89

drivers/clocksource/arm_arch_timer.c

+28 −8
Original line number Diff line number Diff line
@@ -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);