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clocksource/drivers/arm_arch_timer: Introduce generic errata handling…
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… infrastructure

Currently we have code inline in the arch timer probe path to cater for
Freescale erratum A-008585, complete with ifdeffery. This is a little
ugly, and will get worse as we try to add more errata handling.

This patch refactors the handling of Freescale erratum A-008585. Now the
erratum is described in a generic arch_timer_erratum_workaround
structure, and the probe path can iterate over these to detect errata
and enable workarounds.

This will simplify the addition and maintenance of code handling
Hisilicon erratum 161010101.

Signed-off-by: Ding Tianhong <dingtianhong@huawei.com>
[Mark: split patch, correct Kconfig, reword commit message]
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
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Ding Tianhong authored and Daniel Lezcano committed Feb 7, 2017
1 parent 5444ea6 commit 16d10ef
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Showing 3 changed files with 80 additions and 54 deletions.
38 changes: 13 additions & 25 deletions arch/arm64/include/asm/arch_timer.h
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Original file line number Diff line number Diff line change
Expand Up @@ -29,41 +29,29 @@

#include <clocksource/arm_arch_timer.h>

#if IS_ENABLED(CONFIG_FSL_ERRATUM_A008585)
#if IS_ENABLED(CONFIG_ARM_ARCH_TIMER_OOL_WORKAROUND)
extern struct static_key_false arch_timer_read_ool_enabled;
#define needs_fsl_a008585_workaround() \
#define needs_unstable_timer_counter_workaround() \
static_branch_unlikely(&arch_timer_read_ool_enabled)
#else
#define needs_fsl_a008585_workaround() false
#define needs_unstable_timer_counter_workaround() false
#endif

u32 __fsl_a008585_read_cntp_tval_el0(void);
u32 __fsl_a008585_read_cntv_tval_el0(void);
u64 __fsl_a008585_read_cntvct_el0(void);

/*
* The number of retries is an arbitrary value well beyond the highest number
* of iterations the loop has been observed to take.
*/
#define __fsl_a008585_read_reg(reg) ({ \
u64 _old, _new; \
int _retries = 200; \
\
do { \
_old = read_sysreg(reg); \
_new = read_sysreg(reg); \
_retries--; \
} while (unlikely(_old != _new) && _retries); \
\
WARN_ON_ONCE(!_retries); \
_new; \
})
struct arch_timer_erratum_workaround {
const char *id; /* Indicate the Erratum ID */
u32 (*read_cntp_tval_el0)(void);
u32 (*read_cntv_tval_el0)(void);
u64 (*read_cntvct_el0)(void);
};

extern const struct arch_timer_erratum_workaround *timer_unstable_counter_workaround;

#define arch_timer_reg_read_stable(reg) \
({ \
u64 _val; \
if (needs_fsl_a008585_workaround()) \
_val = __fsl_a008585_read_##reg(); \
if (needs_unstable_timer_counter_workaround()) \
_val = timer_unstable_counter_workaround->read_##reg();\
else \
_val = read_sysreg(reg); \
_val; \
Expand Down
4 changes: 4 additions & 0 deletions drivers/clocksource/Kconfig
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Original file line number Diff line number Diff line change
Expand Up @@ -342,10 +342,14 @@ config ARM_ARCH_TIMER_EVTSTREAM
This must be disabled for hardware validation purposes to detect any
hardware anomalies of missing events.

config ARM_ARCH_TIMER_OOL_WORKAROUND
bool

config FSL_ERRATUM_A008585
bool "Workaround for Freescale/NXP Erratum A-008585"
default y
depends on ARM_ARCH_TIMER && ARM64
select ARM_ARCH_TIMER_OOL_WORKAROUND
help
This option enables a workaround for Freescale/NXP Erratum
A-008585 ("ARM generic timer may contain an erroneous
Expand Down
92 changes: 63 additions & 29 deletions drivers/clocksource/arm_arch_timer.c
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Original file line number Diff line number Diff line change
Expand Up @@ -96,27 +96,58 @@ early_param("clocksource.arm_arch_timer.evtstrm", early_evtstrm_cfg);
*/

#ifdef CONFIG_FSL_ERRATUM_A008585
DEFINE_STATIC_KEY_FALSE(arch_timer_read_ool_enabled);
EXPORT_SYMBOL_GPL(arch_timer_read_ool_enabled);

static int fsl_a008585_enable = -1;

u32 __fsl_a008585_read_cntp_tval_el0(void)
/*
* The number of retries is an arbitrary value well beyond the highest number
* of iterations the loop has been observed to take.
*/
#define __fsl_a008585_read_reg(reg) ({ \
u64 _old, _new; \
int _retries = 200; \
\
do { \
_old = read_sysreg(reg); \
_new = read_sysreg(reg); \
_retries--; \
} while (unlikely(_old != _new) && _retries); \
\
WARN_ON_ONCE(!_retries); \
_new; \
})

static u32 notrace fsl_a008585_read_cntp_tval_el0(void)
{
return __fsl_a008585_read_reg(cntp_tval_el0);
}

u32 __fsl_a008585_read_cntv_tval_el0(void)
static u32 notrace fsl_a008585_read_cntv_tval_el0(void)
{
return __fsl_a008585_read_reg(cntv_tval_el0);
}

u64 __fsl_a008585_read_cntvct_el0(void)
static u64 notrace fsl_a008585_read_cntvct_el0(void)
{
return __fsl_a008585_read_reg(cntvct_el0);
}
EXPORT_SYMBOL(__fsl_a008585_read_cntvct_el0);
#endif /* CONFIG_FSL_ERRATUM_A008585 */
#endif

#ifdef CONFIG_ARM_ARCH_TIMER_OOL_WORKAROUND
const struct arch_timer_erratum_workaround *timer_unstable_counter_workaround = NULL;
EXPORT_SYMBOL_GPL(timer_unstable_counter_workaround);

DEFINE_STATIC_KEY_FALSE(arch_timer_read_ool_enabled);
EXPORT_SYMBOL_GPL(arch_timer_read_ool_enabled);

static const struct arch_timer_erratum_workaround ool_workarounds[] = {
#ifdef CONFIG_FSL_ERRATUM_A008585
{
.id = "fsl,erratum-a008585",
.read_cntp_tval_el0 = fsl_a008585_read_cntp_tval_el0,
.read_cntv_tval_el0 = fsl_a008585_read_cntv_tval_el0,
.read_cntvct_el0 = fsl_a008585_read_cntvct_el0,
},
#endif
};
#endif /* CONFIG_ARM_ARCH_TIMER_OOL_WORKAROUND */

static __always_inline
void arch_timer_reg_write(int access, enum arch_timer_reg reg, u32 val,
Expand Down Expand Up @@ -267,8 +298,8 @@ static __always_inline void set_next_event(const int access, unsigned long evt,
arch_timer_reg_write(access, ARCH_TIMER_REG_CTRL, ctrl, clk);
}

#ifdef CONFIG_FSL_ERRATUM_A008585
static __always_inline void fsl_a008585_set_next_event(const int access,
#ifdef CONFIG_ARM_ARCH_TIMER_OOL_WORKAROUND
static __always_inline void erratum_set_next_event_generic(const int access,
unsigned long evt, struct clock_event_device *clk)
{
unsigned long ctrl;
Expand All @@ -286,20 +317,20 @@ static __always_inline void fsl_a008585_set_next_event(const int access,
arch_timer_reg_write(access, ARCH_TIMER_REG_CTRL, ctrl, clk);
}

static int fsl_a008585_set_next_event_virt(unsigned long evt,
static int erratum_set_next_event_virt(unsigned long evt,
struct clock_event_device *clk)
{
fsl_a008585_set_next_event(ARCH_TIMER_VIRT_ACCESS, evt, clk);
erratum_set_next_event_generic(ARCH_TIMER_VIRT_ACCESS, evt, clk);
return 0;
}

static int fsl_a008585_set_next_event_phys(unsigned long evt,
static int erratum_set_next_event_phys(unsigned long evt,
struct clock_event_device *clk)
{
fsl_a008585_set_next_event(ARCH_TIMER_PHYS_ACCESS, evt, clk);
erratum_set_next_event_generic(ARCH_TIMER_PHYS_ACCESS, evt, clk);
return 0;
}
#endif /* CONFIG_FSL_ERRATUM_A008585 */
#endif /* CONFIG_ARM_ARCH_TIMER_OOL_WORKAROUND */

static int arch_timer_set_next_event_virt(unsigned long evt,
struct clock_event_device *clk)
Expand Down Expand Up @@ -329,16 +360,16 @@ static int arch_timer_set_next_event_phys_mem(unsigned long evt,
return 0;
}

static void fsl_a008585_set_sne(struct clock_event_device *clk)
static void erratum_workaround_set_sne(struct clock_event_device *clk)
{
#ifdef CONFIG_FSL_ERRATUM_A008585
#ifdef CONFIG_ARM_ARCH_TIMER_OOL_WORKAROUND
if (!static_branch_unlikely(&arch_timer_read_ool_enabled))
return;

if (arch_timer_uses_ppi == VIRT_PPI)
clk->set_next_event = fsl_a008585_set_next_event_virt;
clk->set_next_event = erratum_set_next_event_virt;
else
clk->set_next_event = fsl_a008585_set_next_event_phys;
clk->set_next_event = erratum_set_next_event_phys;
#endif
}

Expand Down Expand Up @@ -371,7 +402,7 @@ static void __arch_timer_setup(unsigned type,
BUG();
}

fsl_a008585_set_sne(clk);
erratum_workaround_set_sne(clk);
} else {
clk->features |= CLOCK_EVT_FEAT_DYNIRQ;
clk->name = "arch_mem_timer";
Expand Down Expand Up @@ -591,7 +622,7 @@ static void __init arch_counter_register(unsigned type)

clocksource_counter.archdata.vdso_direct = true;

#ifdef CONFIG_FSL_ERRATUM_A008585
#ifdef CONFIG_ARM_ARCH_TIMER_OOL_WORKAROUND
/*
* Don't use the vdso fastpath if errata require using
* the out-of-line counter accessor.
Expand Down Expand Up @@ -879,12 +910,15 @@ static int __init arch_timer_of_init(struct device_node *np)

arch_timer_c3stop = !of_property_read_bool(np, "always-on");

#ifdef CONFIG_FSL_ERRATUM_A008585
if (fsl_a008585_enable < 0)
fsl_a008585_enable = of_property_read_bool(np, "fsl,erratum-a008585");
if (fsl_a008585_enable) {
static_branch_enable(&arch_timer_read_ool_enabled);
pr_info("Enabling workaround for FSL erratum A-008585\n");
#ifdef CONFIG_ARM_ARCH_TIMER_OOL_WORKAROUND
for (i = 0; i < ARRAY_SIZE(ool_workarounds); i++) {
if (of_property_read_bool(np, ool_workarounds[i].id)) {
timer_unstable_counter_workaround = &ool_workarounds[i];
static_branch_enable(&arch_timer_read_ool_enabled);
pr_info("arch_timer: Enabling workaround for %s\n",
timer_unstable_counter_workaround->id);
break;
}
}
#endif

Expand Down

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