[PATCH 1/2] x86/apb_timer: drop unused TSC calibration

Johan Hovold
2020-05-13T10:10:10Z

Drop the APB-timer TSC calibration, which hasn't been used since the
removal of Moorestown support by commit 1a8359e411eb ("x86/mid: Remove
Intel Moorestown").

Signed-off-by: Johan Hovold <johan@kernel.org>
---
arch/x86/include/asm/apb_timer.h | 2 --
arch/x86/kernel/apb_timer.c | 53 --------------------------------
2 files changed, 55 deletions(-)

diff --git a/arch/x86/include/asm/apb_timer.h b/arch/x86/include/asm/apb_timer.h
index 99bb207fc04c..0a9bf8b77a28 100644
--- a/arch/x86/include/asm/apb_timer.h
+++ b/arch/x86/include/asm/apb_timer.h
@@ -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
diff --git a/arch/x86/kernel/apb_timer.c b/arch/x86/kernel/apb_timer.c
index fe698f96617c..263eeaddb0aa 100644
--- a/arch/x86/kernel/apb_timer.c
+++ b/arch/x86/kernel/apb_timer.c
@@ -345,56 +345,3 @@ void __init apbt_time_init(void)
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;
-}
--
2.26.2