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x86/apb_timer: Drop unused TSC calibration

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Drop the APB-timer TSC calibration, which hasn't been used since the
removal of Moorestown support by commit

  1a8359e411 ("x86/mid: Remove Intel Moorestown").

Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200513100944.9171-1-johan@kernel.org
This commit is contained in:
Johan Hovold 2020-05-13 12:09:43 +02:00 committed by Borislav Petkov
parent fd52a75ca3
commit 003d805351
2 changed files with 0 additions and 55 deletions
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2
arch/x86/include/asm/apb_timer.h
View File

@ -28,7 +28,6 @@
#define APBT_DEV_USED 1
extern void apbt_time_init(void);
extern unsigned long apbt_quick_calibrate(void);
extern int arch_setup_apbt_irqs(int irq, int trigger, int mask, int cpu);
extern void apbt_setup_secondary_clock(void);
@ -38,7 +37,6 @@ extern int sfi_mtimer_num;
#else /* CONFIG_APB_TIMER */
static inline unsigned long apbt_quick_calibrate(void) {return 0; }
static inline void apbt_time_init(void) { }
#endif

53
arch/x86/kernel/apb_timer.c
View File

@ -345,56 +345,3 @@ out_noapbt:
apb_timer_block_enabled = 0;
panic("failed to enable APB timer\n");
}
/* called before apb_timer_enable, use early map */
unsigned long apbt_quick_calibrate(void)
{
int i, scale;
u64 old, new;
u64 t1, t2;
unsigned long khz = 0;
u32 loop, shift;
apbt_set_mapping();
dw_apb_clocksource_start(clocksource_apbt);
/* check if the timer can count down, otherwise return */
old = dw_apb_clocksource_read(clocksource_apbt);
i = 10000;
while (--i) {
if (old != dw_apb_clocksource_read(clocksource_apbt))
break;
}
if (!i)
goto failed;
/* count 16 ms */
loop = (apbt_freq / 1000) << 4;
/* restart the timer to ensure it won't get to 0 in the calibration */
dw_apb_clocksource_start(clocksource_apbt);
old = dw_apb_clocksource_read(clocksource_apbt);
old += loop;
t1 = rdtsc();
do {
new = dw_apb_clocksource_read(clocksource_apbt);
} while (new < old);
t2 = rdtsc();
shift = 5;
if (unlikely(loop >> shift == 0)) {
printk(KERN_INFO
"APBT TSC calibration failed, not enough resolution\n");
return 0;
}
scale = (int)div_u64((t2 - t1), loop >> shift);
khz = (scale * (apbt_freq / 1000)) >> shift;
printk(KERN_INFO "TSC freq calculated by APB timer is %lu khz\n", khz);
return khz;
failed:
return 0;
}