[U-Boot] [PATCH v6 1/2] x86: Add TSC-specific timer functions

[Bin Meng]

Hi Ivan,

On Fri, Apr 13, 2018 at 6:12 AM, Ivan Gorinov <ivan.gorinov at intel.com> wrote:
> Coreboot timestamp functions and Quark memory reference code use
> get_tbclk() to get TSC frequency. This will not work if another
> early timer is selected.
>

Thanks for working on this. But get_tbclk() is one API provided by the
timer library. The get_tbclk_mhz() is something that is implemented by
the TSC timer driver, so can we get rid of the get_tbclk_mhz() and use
the get_tbclk() instead in coreboot/timestamp.c and quark/mrc_util.c?

> Add tsc_rate_mhz() function and use it in the code that specifically
> needs to get TSC rate regardless of currently selected early timer.
>
> Signed-off-by: Ivan Gorinov <ivan.gorinov at intel.com>
> ---
>  arch/x86/cpu/coreboot/timestamp.c |  2 +-
>  arch/x86/cpu/quark/mrc_util.c     | 13 ++++++-------
>  arch/x86/include/asm/u-boot-x86.h |  2 +-
>  drivers/timer/tsc_timer.c         | 33 ++++++++++++++++++++++++---------
>  4 files changed, 32 insertions(+), 18 deletions(-)
>
> diff --git a/arch/x86/cpu/coreboot/timestamp.c b/arch/x86/cpu/coreboot/timestamp.c
> index b382795..05bb214 100644
> --- a/arch/x86/cpu/coreboot/timestamp.c
> +++ b/arch/x86/cpu/coreboot/timestamp.c
> @@ -78,7 +78,7 @@ int timestamp_add_to_bootstage(void)
>                 if (name) {
>                         bootstage_add_record(0, name, BOOTSTAGEF_ALLOC,
>                                              tse->entry_stamp /
> -                                                       get_tbclk_mhz());
> +                                                       tsc_rate_mhz());
>                 }
>         }
>
> diff --git a/arch/x86/cpu/quark/mrc_util.c b/arch/x86/cpu/quark/mrc_util.c
> index fac2d72..4794395 100644
> --- a/arch/x86/cpu/quark/mrc_util.c
> +++ b/arch/x86/cpu/quark/mrc_util.c
> @@ -57,19 +57,18 @@ void mrc_post_code(uint8_t major, uint8_t minor)
>  void delay_n(uint32_t ns)
>  {
>         /* 1000 MHz clock has 1ns period --> no conversion required */
> -       uint64_t final_tsc = rdtsc();
> +       uint64_t start_tsc = rdtsc();
> +       uint64_t ticks;
>
> -       final_tsc += ((get_tbclk_mhz() * ns) / 1000);
> -
> -       while (rdtsc() < final_tsc)
> -               ;
> +       ticks = (tsc_rate_mhz() * ns) / 1000;
> +       while (rdtsc() - start_tsc < ticks);
>  }
>
>  /* Delay number of microseconds */
> -void delay_u(uint32_t ms)
> +void delay_u(uint32_t us)
>  {
>         /* 64-bit math is not an option, just use loops */
> -       while (ms--)
> +       while (us--)
>                 delay_n(1000);
>  }
>
> diff --git a/arch/x86/include/asm/u-boot-x86.h b/arch/x86/include/asm/u-boot-x86.h
> index 187fe5f..de68120 100644
> --- a/arch/x86/include/asm/u-boot-x86.h
> +++ b/arch/x86/include/asm/u-boot-x86.h
> @@ -29,7 +29,7 @@ int cleanup_before_linux(void);
>  void timer_isr(void *);
>  typedef void (timer_fnc_t) (void);
>  int register_timer_isr (timer_fnc_t *isr_func);
> -unsigned long get_tbclk_mhz(void);
> +unsigned long tsc_rate_mhz(void);
>  void timer_set_base(uint64_t base);
>  int i8254_init(void);
>
> diff --git a/drivers/timer/tsc_timer.c b/drivers/timer/tsc_timer.c
> index 9296de6..98cbf12 100644
> --- a/drivers/timer/tsc_timer.c
> +++ b/drivers/timer/tsc_timer.c
> @@ -277,15 +277,12 @@ success:
>         return delta / 1000;
>  }
>
> -/* Get the speed of the TSC timer in MHz */
> -unsigned notrace long get_tbclk_mhz(void)
> -{
> -       return get_tbclk() / 1000000;
> -}
> -
>  static ulong get_ms_timer(void)
>  {
> -       return (get_ticks() * 1000) / get_tbclk();
> +       if (gd->arch.clock_rate == 0)
> +               return 0;
> +
> +       return (rdtsc() * 1000) / gd->arch.clock_rate;
>  }
>
>  ulong get_timer(ulong base)
> @@ -295,7 +292,10 @@ ulong get_timer(ulong base)
>
>  ulong notrace timer_get_us(void)
>  {
> -       return get_ticks() / get_tbclk_mhz();
> +       if (gd->arch.clock_rate == 0)
> +               return 0;
> +
> +       return (rdtsc() * 1000000) / gd->arch.clock_rate;
>  }
>
>  ulong timer_get_boot_us(void)
> @@ -308,7 +308,7 @@ void __udelay(unsigned long usec)
>         u64 now = get_ticks();
>         u64 stop;
>
> -       stop = now + usec * get_tbclk_mhz();
> +       stop = now + ((u64)usec * gd->arch.clock_rate) / 1000000;
>
>         while ((int64_t)(stop - get_ticks()) > 0)
>  #if defined(CONFIG_QEMU) && defined(CONFIG_SMP)
> @@ -355,6 +355,14 @@ static void tsc_timer_ensure_setup(void)
>         }
>  }
>
> +/* Get the speed of the TSC timer in MHz */
> +unsigned notrace long tsc_rate_mhz(void)
> +{
> +       tsc_timer_ensure_setup();
> +
> +       return gd->arch.clock_rate / 1000000;
> +}
> +
>  static int tsc_timer_probe(struct udevice *dev)
>  {
>         struct timer_dev_priv *uc_priv = dev_get_uclass_priv(dev);
> @@ -365,6 +373,13 @@ static int tsc_timer_probe(struct udevice *dev)
>         return 0;
>  }
>
> +int timer_init(void)
> +{
> +       tsc_timer_ensure_setup();
> +
> +       return 0;
> +}
> +
>  unsigned long notrace timer_early_get_rate(void)
>  {
>         tsc_timer_ensure_setup();
> --

Regards,
Bin