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Commit 5ef19a16 authored by Marc Zyngier's avatar Marc Zyngier Committed by Will Deacon
Browse files

clocksource/arm_arch_timer: Direcly assign set_next_event workaround 



When a given timer is affected by an erratum and requires an
alternative implementation of set_next_event, we do a rather
complicated dance to detect and call the workaround on each
set_next_event call.

This is clearly idiotic, as we can perfectly detect whether
this CPU requires a workaround while setting up the clock event
device.

This only requires the CPU-specific detection to be done a bit
earlier, and we can then safely override the set_next_event pointer
if we have a workaround associated to that CPU.

Acked-by: default avatarMark Rutland <mark.rutland@arm.com>
Acked-by; Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
parent dea86a80

arch/arm/include/asm/arch_timer.h

+4 −0
Original line number Diff line number Diff line
@@ -11,6 +11,10 @@ 
#include <clocksource/arm_arch_timer.h>



#ifdef CONFIG_ARM_ARCH_TIMER

/* 32bit ARM doesn't know anything about timer errata... */

#define has_erratum_handler(h)		(false)

#define erratum_handler(h)		(arch_timer_##h)



int arch_timer_arch_init(void);



/*

arch/arm64/include/asm/arch_timer.h

+16 −0
Original line number Diff line number Diff line
@@ -31,10 +31,26 @@ 
#include <clocksource/arm_arch_timer.h>



#if IS_ENABLED(CONFIG_ARM_ARCH_TIMER_OOL_WORKAROUND)

#define has_erratum_handler(h)						\

	({								\

		const struct arch_timer_erratum_workaround *__wa;	\

		__wa = __this_cpu_read(timer_unstable_counter_workaround); \

		(__wa && __wa->h);					\

	})



#define erratum_handler(h)						\

	({								\

		const struct arch_timer_erratum_workaround *__wa;	\

		__wa = __this_cpu_read(timer_unstable_counter_workaround); \

		(__wa && __wa->h) ? __wa->h : arch_timer_##h;		\

	})



extern struct static_key_false arch_timer_read_ool_enabled;

#define needs_unstable_timer_counter_workaround() \

	static_branch_unlikely(&arch_timer_read_ool_enabled)

#else

#define has_erratum_handler(h)			   false

#define erratum_handler(h)			   (arch_timer_##h)

#define needs_unstable_timer_counter_workaround()  false

#endif

drivers/clocksource/arm_arch_timer.c

+8 −38
Original line number Diff line number Diff line
@@ -598,36 +598,12 @@ static void arch_timer_check_ool_workaround(enum arch_timer_erratum_match_type t 
		local ? "local" : "global", wa->desc);

}



#define erratum_handler(fn, r, ...)					\

({									\

	bool __val;							\

	if (needs_unstable_timer_counter_workaround()) {		\

		const struct arch_timer_erratum_workaround *__wa;	\

		__wa = __this_cpu_read(timer_unstable_counter_workaround); \

		if (__wa && __wa->fn) {					\

			r = __wa->fn(__VA_ARGS__);			\

			__val = true;					\

		} else {						\

			__val = false;					\

		}							\

	} else {							\

		__val = false;						\

	}								\

	__val;								\

})



static bool arch_timer_this_cpu_has_cntvct_wa(void)

{

	const struct arch_timer_erratum_workaround *wa;



	wa = __this_cpu_read(timer_unstable_counter_workaround);

	return wa && wa->read_cntvct_el0;

	return has_erratum_handler(read_cntvct_el0);

}

#else

#define arch_timer_check_ool_workaround(t,a)		do { } while(0)

#define erratum_set_next_event_tval_virt(...)		({BUG(); 0;})

#define erratum_set_next_event_tval_phys(...)		({BUG(); 0;})

#define erratum_handler(fn, r, ...)			({false;})

#define arch_timer_this_cpu_has_cntvct_wa()		({false;})

#endif /* CONFIG_ARM_ARCH_TIMER_OOL_WORKAROUND */
@@ -721,11 +697,6 @@ static __always_inline void set_next_event(const int access, unsigned long evt, 
static int arch_timer_set_next_event_virt(unsigned long evt,

					  struct clock_event_device *clk)

{

	int ret;



	if (erratum_handler(set_next_event_virt, ret, evt, clk))

		return ret;



	set_next_event(ARCH_TIMER_VIRT_ACCESS, evt, clk);

	return 0;

}
@@ -733,11 +704,6 @@ static int arch_timer_set_next_event_virt(unsigned long evt, 
static int arch_timer_set_next_event_phys(unsigned long evt,

					  struct clock_event_device *clk)

{

	int ret;



	if (erratum_handler(set_next_event_phys, ret, evt, clk))

		return ret;



	set_next_event(ARCH_TIMER_PHYS_ACCESS, evt, clk);

	return 0;

}
@@ -762,6 +728,10 @@ static void __arch_timer_setup(unsigned type, 
	clk->features = CLOCK_EVT_FEAT_ONESHOT;



	if (type == ARCH_TIMER_TYPE_CP15) {

		typeof(clk->set_next_event) sne;



		arch_timer_check_ool_workaround(ate_match_local_cap_id, NULL);



		if (arch_timer_c3stop)

			clk->features |= CLOCK_EVT_FEAT_C3STOP;

		clk->name = "arch_sys_timer";
@@ -772,20 +742,20 @@ static void __arch_timer_setup(unsigned type, 
		case ARCH_TIMER_VIRT_PPI:

			clk->set_state_shutdown = arch_timer_shutdown_virt;

			clk->set_state_oneshot_stopped = arch_timer_shutdown_virt;

			clk->set_next_event = arch_timer_set_next_event_virt;

			sne = erratum_handler(set_next_event_virt);

			break;

		case ARCH_TIMER_PHYS_SECURE_PPI:

		case ARCH_TIMER_PHYS_NONSECURE_PPI:

		case ARCH_TIMER_HYP_PPI:

			clk->set_state_shutdown = arch_timer_shutdown_phys;

			clk->set_state_oneshot_stopped = arch_timer_shutdown_phys;

			clk->set_next_event = arch_timer_set_next_event_phys;

			sne = erratum_handler(set_next_event_phys);

			break;

		default:

			BUG();

		}



		arch_timer_check_ool_workaround(ate_match_local_cap_id, NULL);

		clk->set_next_event = sne;

	} else {

		clk->features |= CLOCK_EVT_FEAT_DYNIRQ;

		clk->name = "arch_mem_timer";