Re: [PATCH] x86, apic: Add apic calibration hook.

[Alok Kataria <akataria@vmware.com>]

On Wed, 2010-08-18 at 10:41 -0700, Alok Kataria wrote:
> Add a new function pointer calibrate_apic to x86_platform_ops.

I guess I should move this in init_ops too, anything else that needs to
be changed ? 

Thanks,
Alok

>  On native this
> does the usual apic calibration. On VMware's platform we override it with a
> routine which gets that information from the hypervisor.
> 
> Signed-off-by: Alok N Kataria <akataria@vmware.com>
> Cc: H. Peter Anvin <hpa@zytor.com>
> 
> Index: linux-x86-tree.git/arch/x86/include/asm/apic.h
> ===================================================================
> --- linux-x86-tree.git.orig/arch/x86/include/asm/apic.h	2010-08-17 15:29:21.000000000 -0700
> +++ linux-x86-tree.git/arch/x86/include/asm/apic.h	2010-08-17 15:32:11.000000000 -0700
> @@ -238,6 +238,7 @@ extern void setup_boot_APIC_clock(void);
>  extern void setup_secondary_APIC_clock(void);
>  extern int APIC_init_uniprocessor(void);
>  extern void enable_NMI_through_LVT0(void);
> +extern unsigned int native_calibrate_apic(void);
>  
>  /*
>   * On 32bit this is mach-xxx local
> Index: linux-x86-tree.git/arch/x86/include/asm/x86_init.h
> ===================================================================
> --- linux-x86-tree.git.orig/arch/x86/include/asm/x86_init.h	2010-08-17 15:29:21.000000000 -0700
> +++ linux-x86-tree.git/arch/x86/include/asm/x86_init.h	2010-08-18 10:20:21.000000000 -0700
> @@ -143,6 +143,7 @@ struct x86_cpuinit_ops {
>   * @is_untracked_pat_range	exclude from PAT logic
>   * @nmi_init			enable NMI on cpus
>   * @i8042_detect		pre-detect if i8042 controller exists
> + * @calibrate_apic:		calibrate APIC bus freq
>   */
>  struct x86_platform_ops {
>  	unsigned long (*calibrate_tsc)(void);
> @@ -152,6 +153,7 @@ struct x86_platform_ops {
>  	bool (*is_untracked_pat_range)(u64 start, u64 end);
>  	void (*nmi_init)(void);
>  	int (*i8042_detect)(void);
> +	unsigned int (*calibrate_apic)(void);
>  };
>  
>  extern struct x86_init_ops x86_init;
> Index: linux-x86-tree.git/arch/x86/kernel/apic/apic.c
> ===================================================================
> --- linux-x86-tree.git.orig/arch/x86/kernel/apic/apic.c	2010-08-17 15:29:21.000000000 -0700
> +++ linux-x86-tree.git/arch/x86/kernel/apic/apic.c	2010-08-18 10:20:55.000000000 -0700
> @@ -176,7 +176,7 @@ static struct resource lapic_resource = 
>  	.flags = IORESOURCE_MEM | IORESOURCE_BUSY,
>  };
>  
> -static unsigned int calibration_result;
> +static unsigned int apic_calibration_res;
>  
>  static int lapic_next_event(unsigned long delta,
>  			    struct clock_event_device *evt);
> @@ -431,7 +431,7 @@ static void lapic_timer_setup(enum clock
>  	switch (mode) {
>  	case CLOCK_EVT_MODE_PERIODIC:
>  	case CLOCK_EVT_MODE_ONESHOT:
> -		__setup_APIC_LVTT(calibration_result,
> +		__setup_APIC_LVTT(apic_calibration_res,
>  				  mode != CLOCK_EVT_MODE_PERIODIC, 1);
>  		break;
>  	case CLOCK_EVT_MODE_UNUSED:
> @@ -590,13 +590,46 @@ calibrate_by_pmtimer(long deltapm, long 
>  	return 0;
>  }
>  
> +static void __init initialize_lapic_clkevt(long delta)
> +{
> +	/* Calculate the scaled math multiplication factor */
> +	lapic_clockevent.mult = div_sc(delta, TICK_NSEC * LAPIC_CAL_LOOPS,
> +				       lapic_clockevent.shift);
> +	lapic_clockevent.max_delta_ns =
> +		clockevent_delta2ns(0x7FFFFF, &lapic_clockevent);
> +	lapic_clockevent.min_delta_ns =
> +		clockevent_delta2ns(0xF, &lapic_clockevent);
> +}
> +
>  static int __init calibrate_APIC_clock(void)
>  {
> +	apic_calibration_res = x86_platform.calibrate_apic();
> +	if (apic_calibration_res) {
> +		struct clock_event_device *levt = &__get_cpu_var(lapic_events);
> +		long delta;
> +
> +		if (lapic_clockevent.mult)
> +			return 0;
> +
> +		delta = (apic_calibration_res * LAPIC_CAL_LOOPS) / APIC_DIVISOR;
> +		initialize_lapic_clkevt(delta);
> +		levt->features &= ~CLOCK_EVT_FEAT_DUMMY;
> +		return 0;
> +	} else {
> +		pr_warning("Unable to calibrate APIC frequency, "
> +			   "disabling apic timer\n");
> +		return -1;
> +	}
> +}
> +
> +unsigned int __init native_calibrate_apic(void)
> +{
>  	struct clock_event_device *levt = &__get_cpu_var(lapic_events);
>  	void (*real_handler)(struct clock_event_device *dev);
>  	unsigned long deltaj;
>  	long delta, deltatsc;
>  	int pm_referenced = 0;
> +	unsigned int calibration_result;
>  
>  	local_irq_disable();
>  
> @@ -631,14 +664,7 @@ static int __init calibrate_APIC_clock(v
>  	pm_referenced = !calibrate_by_pmtimer(lapic_cal_pm2 - lapic_cal_pm1,
>  					&delta, &deltatsc);
>  
> -	/* Calculate the scaled math multiplication factor */
> -	lapic_clockevent.mult = div_sc(delta, TICK_NSEC * LAPIC_CAL_LOOPS,
> -				       lapic_clockevent.shift);
> -	lapic_clockevent.max_delta_ns =
> -		clockevent_delta2ns(0x7FFFFF, &lapic_clockevent);
> -	lapic_clockevent.min_delta_ns =
> -		clockevent_delta2ns(0xF, &lapic_clockevent);
> -
> +	initialize_lapic_clkevt(delta);
>  	calibration_result = (delta * APIC_DIVISOR) / LAPIC_CAL_LOOPS;
>  
>  	apic_printk(APIC_VERBOSE, "..... delta %ld\n", delta);
> @@ -664,7 +690,7 @@ static int __init calibrate_APIC_clock(v
>  	if (calibration_result < (1000000 / HZ)) {
>  		local_irq_enable();
>  		pr_warning("APIC frequency too slow, disabling apic timer\n");
> -		return -1;
> +		return 0;
>  	}
>  
>  	levt->features &= ~CLOCK_EVT_FEAT_DUMMY;
> @@ -706,10 +732,10 @@ static int __init calibrate_APIC_clock(v
>  
>  	if (levt->features & CLOCK_EVT_FEAT_DUMMY) {
>  		pr_warning("APIC timer disabled due to verification failure\n");
> -			return -1;
> +			return 0;
>  	}
>  
> -	return 0;
> +	return calibration_result;
>  }
>  
>  /*
> Index: linux-x86-tree.git/arch/x86/kernel/cpu/vmware.c
> ===================================================================
> --- linux-x86-tree.git.orig/arch/x86/kernel/cpu/vmware.c	2010-08-17 15:29:21.000000000 -0700
> +++ linux-x86-tree.git/arch/x86/kernel/cpu/vmware.c	2010-08-18 10:20:21.000000000 -0700
> @@ -72,17 +72,33 @@ static unsigned long vmware_get_tsc_khz(
>  	return tsc_hz;
>  }
>  
> +static unsigned int vmware_calibrate_apic(void)
> +{
> +	unsigned int calibration_result;
> +	uint32_t eax, ebx, ecx, edx;
> +
> +	VMWARE_PORT(GETHZ, eax, ebx, ecx, edx);
> +	BUG_ON(!ecx);
> +	calibration_result = ecx / HZ;
> +
> +	printk(KERN_INFO "APIC bus freq read from hypervisor : %u.%03u MHz\n",
> +			 calibration_result / (1000000 / HZ),
> +			 calibration_result % (1000000 / HZ));
> +	return calibration_result;
> +}
> +
>  static void __init vmware_platform_setup(void)
>  {
>  	uint32_t eax, ebx, ecx, edx;
>  
>  	VMWARE_PORT(GETHZ, eax, ebx, ecx, edx);
>  
> -	if (ebx != UINT_MAX)
> +	if (ebx != UINT_MAX) {
>  		x86_platform.calibrate_tsc = vmware_get_tsc_khz;
> -	else
> +		x86_platform.calibrate_apic = vmware_calibrate_apic;
> +	} else
>  		printk(KERN_WARNING
> -		       "Failed to get TSC freq from the hypervisor\n");
> +		       "Failed to setup VMware hypervisor platform\n");
>  }
>  
>  /*
> Index: linux-x86-tree.git/arch/x86/kernel/x86_init.c
> ===================================================================
> --- linux-x86-tree.git.orig/arch/x86/kernel/x86_init.c	2010-08-17 15:29:21.000000000 -0700
> +++ linux-x86-tree.git/arch/x86/kernel/x86_init.c	2010-08-17 16:44:20.000000000 -0700
> @@ -95,7 +95,8 @@ struct x86_platform_ops x86_platform = {
>  	.iommu_shutdown			= iommu_shutdown_noop,
>  	.is_untracked_pat_range		= is_ISA_range,
>  	.nmi_init			= default_nmi_init,
> -	.i8042_detect			= default_i8042_detect
> +	.i8042_detect			= default_i8042_detect,
> +	.calibrate_apic			= native_calibrate_apic
>  };
>  
>  EXPORT_SYMBOL_GPL(x86_platform);
>