[PATCH 1/2] x86/mrst: Auto detect freq for local timers

From: Jacob Pan
Date: Fri May 14 2010 - 16:45:46 EST

Some Intel CPUs can directly get fsb frequency and bus ratio from
various MSRs. This patch enables this feature and benefit Medfield
platform.

Signed-off-by: Alek Du <alek.du@xxxxxxxxx>
Signed-off-by: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
---
arch/x86/include/asm/processor.h | 3 +++
arch/x86/kernel/cpu/intel.c | 34 ++++++++++++++++++++++++++++++++++
arch/x86/kernel/mrst.c | 32 ++++++++++++++++++++++++--------
3 files changed, 61 insertions(+), 8 deletions(-)

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 32428b4..f72107f 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -94,6 +94,9 @@ struct cpuinfo_x86 {
int x86_cache_alignment; /* In bytes */
int x86_power;
unsigned long loops_per_jiffy;
+ /* support TSC and LAPIC non-calibartion way */
+ __u32 bus_ratio;
+ __u32 fsb; /* In khz */
#ifdef CONFIG_SMP
/* cpus sharing the last level cache: */
cpumask_var_t llc_shared_map;
diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
index 85f69cd..f620abc 100644
--- a/arch/x86/kernel/cpu/intel.c
+++ b/arch/x86/kernel/cpu/intel.c
@@ -27,6 +27,38 @@
#include <asm/apic.h>
#endif

+/* MSR_FSB_FREQ in Khz */
+const u32 fsb[] = {266667, 133333, 200000, 166667, 333333, 100000, 400000, 0};
+/* detect Intel cpus that can do TSC/LAPIC non-calibration way */
+static void __cpuinit intel_tsc_fsb(struct cpuinfo_x86 *c)
+{
+ u32 lo, hi;
+
+ if (c->x86 != 6)
+ return;
+ if (c->x86_model != 0xf && /* core 2 duo */
+ c->x86_model != 0x17 && /* core 2 extreme */
+ c->x86_model != 0x1c && /* atom */
+ c->x86_model != 0x26 && /* lincroft */
+ c->x86_model != 0x27) /* penwell */
+ return;
+ rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
+ if (lo >> 31)
+ c->bus_ratio = (hi >> 8) & 0x1f;
+ else {
+ rdmsr(MSR_IA32_PLATFORM_ID, lo, hi);
+ c->bus_ratio = (lo >> 8) & 0x1f;
+ }
+ c->fsb = fsb[lo & 0x7];
+ if (c->x86_model == 0x27) { /* penwell special */
+ rdmsr(MSR_FSB_FREQ, lo, hi);
+ if ((lo & 0x7) == 0x7)
+ c->fsb = 83200;
+ else c->fsb = 99840;
+ }
+ printk(KERN_INFO "Detect CPU bus ratio %d, fsb %d khz\n", c->bus_ratio, c->fsb);
+}
+
static void __cpuinit early_init_intel(struct cpuinfo_x86 *c)
{
/* Unmask CPUID levels if masked: */
@@ -46,6 +78,8 @@ static void __cpuinit early_init_intel(struct cpuinfo_x86 *c)
(c->x86 == 0x6 && c->x86_model >= 0x0e))
set_cpu_cap(c, X86_FEATURE_CONSTANT_TSC);

+ intel_tsc_fsb(c);
+
/*
* Atom erratum AAE44/AAF40/AAG38/AAH41:
*
diff --git a/arch/x86/kernel/mrst.c b/arch/x86/kernel/mrst.c
index 9b62d32..c553d10 100644
--- a/arch/x86/kernel/mrst.c
+++ b/arch/x86/kernel/mrst.c
@@ -209,14 +209,31 @@ static unsigned long __init mrst_calibrate_tsc(void)
{
unsigned long flags, fast_calibrate;

- local_irq_save(flags);
- fast_calibrate = apbt_quick_calibrate();
- local_irq_restore(flags);
+ if (mrst_cpu_chip == MRST_CPU_CHIP_PENWELL) {
+ fast_calibrate = boot_cpu_data.bus_ratio * boot_cpu_data.fsb;
+ pr_debug("read penwell tsc %lu khz\n", fast_calibrate);
+ lapic_timer_frequency = boot_cpu_data.fsb * 1000 / HZ;
+ /* mark tsc clocksource as reliable */
+ set_cpu_cap(&boot_cpu_data, X86_FEATURE_TSC_RELIABLE);
+ } else {
+ /**
+ * TODO: calibrate lapic timer with apbt, if we use apbt only,
+ * there is no need to calibrate lapic timer, since they are
+ * not used.
+ * if we use lapic timers and apbt, the default calibration
+ * should work, since we have the global clockevent setup.
+ * but it would be more efficient if we combine the lapic timer
+ * with tsc calibration.
+ */
+ local_irq_save(flags);
+ fast_calibrate = apbt_quick_calibrate();
+ local_irq_restore(flags);
+ }

- if (fast_calibrate)
- return fast_calibrate;
+ pr_info("tsc lapic calibration results %lu %d\n",
+ fast_calibrate, lapic_timer_frequency);

- return 0;
+ return fast_calibrate;
}

void __init mrst_time_init(void)
@@ -271,8 +288,7 @@ static void __init mrst_setup_boot_clock(void)
int mrst_identify_cpu(void)
{
if (boot_cpu_data.x86 == 6 &&
- boot_cpu_data.x86_model == 0x27 &&
- boot_cpu_data.x86_mask == 1)
+ boot_cpu_data.x86_model == 0x27)
mrst_cpu_chip = MRST_CPU_CHIP_PENWELL;
else if (boot_cpu_data.x86 == 6 &&
boot_cpu_data.x86_model == 0x26)
--
1.7.0.4


On Tue, 11 May 2010 22:36:39 +0800
Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote:

> On Fri, 7 May 2010, Jacob Pan wrote:
>
> > From: Jacob Pan <jacob.jun.pan@xxxxxxxxx>
> >
> > Penwell has added always on lapic timers and tsc, we want to treat
> > it as a variant of moorestown so that one binary kernel can boot on both.
> > this patch added clock selction logic so that platform code can set up the
> > optimal configuration for both moorestown and medfield.
> >
> > This patch will also mark Penwell TSC reliable, thus no need for
> > watchdog clocksource to monitor it.
> >
> > Signed-off-by: Alek Du <alek.du@xxxxxxxxx>
> > Signed-off-by: Jacob Pan <jacob.jun.pan@xxxxxxxxx>
> > Signed-off-by: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
> > ---
> > arch/x86/include/asm/mrst.h | 30 +++++++++++
> > arch/x86/kernel/mrst.c | 119 ++++++++++++++++++++++++++++++++++++++----
> > 2 files changed, 137 insertions(+), 12 deletions(-)
> >
> > diff --git a/arch/x86/include/asm/mrst.h b/arch/x86/include/asm/mrst.h
> > index 451d30e..3054407 100644
> > --- a/arch/x86/include/asm/mrst.h
> > +++ b/arch/x86/include/asm/mrst.h
> > @@ -11,7 +11,37 @@
> > #ifndef _ASM_X86_MRST_H
> > #define _ASM_X86_MRST_H
> > extern int pci_mrst_init(void);
> > +extern unsigned int calibration_result;
>
> Yuck, why is this in a mrst specific header ?
>
> > +
> > +#define MRST_TIMER_DEFAULT 0
> > +#define MRST_TIMER_APBT_ONLY 1
> > +#define MRST_TIMER_LAPIC_APBT 2
>
> enum please, also
>
> > +/**
> > + * the clockevent devices on Moorestown/Medfield can be APBT or LAPIC clock,
> > + * cmdline option x86_mrst_timer can be used to override the configuration
> > + * to prefer one or the other.
> > + * at runtime, there are basically three timer configurations:
> > + * 1. per cpu apbt clock only
> > + * 2. per cpu always-on lapic clocks only, this is Penwell/Medfield only
> > + * 3. per cpu lapic clock (C3STOP) and one apbt clock, with broadcast.
> > + *
> > + * by default (without cmdline option), platform code first detects cpu type
> > + * to see if we are on lincroft or penwell, then set up both lapic or apbt
> > + * clocks accordingly.
> > + * i.e. by default, medfield uses configuration #2, moorestown uses #1.
> > + * config #3 is supported but not recommended on medfield.
> > + *
> > + * rating and feature summary:
> > + * lapic (with C3STOP) --------- 100
> > + * apbt (always-on) ------------ 110
>
> apbt sucks performance wise, so why do you consider it a better
> choice than lapic + broadcast ?
>
> > + * lapic (always-on,ARAT) ------ 150
> > + */
> > +
> > +int mrst_timer_options __cpuinitdata;
> > +
> > static u32 sfi_mtimer_usage[SFI_MTMR_MAX_NUM];
> > static struct sfi_timer_table_entry sfi_mtimer_array[SFI_MTMR_MAX_NUM];
> > +static u32 mrst_cpu_chip;
> > int sfi_mtimer_num;
> >
> > struct sfi_rtc_table_entry sfi_mrtc_array[SFI_MRTC_MAX];
> > @@ -167,15 +191,16 @@ int __init sfi_parse_mrtc(struct sfi_table_header *table)
> > return 0;
> > }
> >
> > -/*
> > - * the secondary clock in Moorestown can be APBT or LAPIC clock, default to
> > - * APBT but cmdline option can also override it.
> > - */
> > static void __cpuinit mrst_setup_secondary_clock(void)
> > {
> > - /* restore default lapic clock if disabled by cmdline */
> > - if (disable_apbt_percpu)
> > - return setup_secondary_APIC_clock();
> > + if ((mrst_timer_options == MRST_TIMER_APBT_ONLY))
> > + return apbt_setup_secondary_clock();
> > + if (cpu_has(&current_cpu_data, X86_FEATURE_ARAT)
> > + || (mrst_timer_options == MRST_TIMER_LAPIC_APBT)) {
> > + pr_info("using lapic timers for secondary clock\n");
> > + setup_secondary_APIC_clock();
> > + return;
>
> The logic is confusing.
>
> > + }
> > apbt_setup_secondary_clock();
> > }
> >
> > @@ -183,9 +208,45 @@ static unsigned long __init mrst_calibrate_tsc(void)
> > {
> > unsigned long flags, fast_calibrate;
> >
> > - local_irq_save(flags);
> > - fast_calibrate = apbt_quick_calibrate();
> > - local_irq_restore(flags);
> > + if (mrst_cpu_chip == MRST_CPU_CHIP_PENWELL) {
> > + u32 lo, hi, ratio, fsb;
> > +
> > + rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
> > + pr_debug("IA32 perf status is 0x%x, 0x%0x\n", lo, hi);
> > + ratio = (hi >> 8) & 0x1f;
> > + pr_debug("ratio is %d\n", ratio);
> > + if (!ratio) {
> > + pr_err("read a zero ratio, should be incorrect!\n");
> > + pr_err("force tsc ratio to 16 ...\n");
> > + ratio = 16;
> > + }
>
> This is not Penwell specific at all. The ratio can be read out on all
> Core based CPUs either from MSR_PLATFORM_ID[12:8] or
> MSR_PERF_STAT[44:40] depending on XE operation enabled
> (MSR_PERF_STAT[31] == 1)
>
> This should be made general available and not burried into the mrst
> code.
>
> > + rdmsr(MSR_FSB_FREQ, lo, hi);
> > + if ((lo & 0x7) == 0x7)
> > + fsb = PENWELL_FSB_FREQ_83SKU;
> > + else
> > + fsb = PENWELL_FSB_FREQ_100SKU;
>
> I guess the 111 is Penwell/MRST specific, right ?
>
> According to SDM we have anyway different results for the various CPU
> families, but we should utilize this in a generic way and have the
> translation tables for the various CPUs in one place.
>
> > + fast_calibrate = ratio * fsb;
> > + pr_debug("read penwell tsc %lu khz\n", fast_calibrate);
> > + calibration_result = fsb * 1000 / HZ;
> > + /* mark tsc clocksource as reliable */
> > + set_cpu_cap(&boot_cpu_data, X86_FEATURE_TSC_RELIABLE);
> > + } else {
> > + /**
> > + * TODO: calibrate lapic timer with apbt, if we use apbt only,
> > + * there is no need to calibrate lapic timer, since they are
> > + * not used.
> > + * if we use lapic timers and apbt, the default calibration
> > + * should work, since we have the global clockevent setup.
> > + * but it would be more efficient if we combine the lapic timer
> > + * with tsc calibration.
> > + */
> > + local_irq_save(flags);
> > + fast_calibrate = apbt_quick_calibrate();
> > + local_irq_restore(flags);
> > + }
> > +
> > + pr_info("tsc lapic calibration results %lu %d\n",
> > + fast_calibrate, calibration_result);
> >
> > if (fast_calibrate)
> > return fast_calibrate;
> > @@ -195,6 +256,11 @@ static unsigned long __init mrst_calibrate_tsc(void)
> >
> > void __init mrst_time_init(void)
> > {
> > + /* if cpu is penwell, lapic timer will be used by default */
> > + if ((mrst_cpu_chip == MRST_CPU_CHIP_PENWELL) &&
> > + (mrst_timer_options == MRST_TIMER_DEFAULT))
> > + return;
> > +
> > sfi_table_parse(SFI_SIG_MTMR, NULL, NULL, sfi_parse_mtmr);
> > pre_init_apic_IRQ0();
> > apbt_time_init();
> > @@ -211,11 +277,38 @@ void __init mrst_rtc_init(void)
> > */
> > static void __init mrst_setup_boot_clock(void)
> > {
> > - pr_info("%s: per cpu apbt flag %d \n", __func__, disable_apbt_percpu);
> > - if (disable_apbt_percpu)
> > + if (mrst_timer_options == MRST_TIMER_APBT_ONLY)
> > + return;
> > + if ((mrst_timer_options == MRST_TIMER_LAPIC_APBT)
> > + || (mrst_cpu_chip == MRST_CPU_CHIP_PENWELL))
> > setup_boot_APIC_clock();
> > };
> >
> > +enum cpuid_regs {
> > + CR_EAX = 0,
> > + CR_ECX,
> > + CR_EDX,
> > + CR_EBX
> > +};
> > +
> > +int mrst_identify_cpu(void)
> > +{
> > + u32 regs[4];
> > +
> > + cpuid(1, &regs[CR_EAX], &regs[CR_EBX], &regs[CR_ECX], &regs[CR_EDX]);
>
> Yikes. From which Intel cookbook is this ?
>
> Aside of that we have that info in boot_cpu_info already, don't we ?
> So there is neither a requirement for the extra cpuid call nor for
> the extra mrst_cpu_chip id magic.
>
> > + if ((regs[CR_EAX] & PENWELL_FAMILY) == PENWELL_FAMILY)
> > + mrst_cpu_chip = MRST_CPU_CHIP_PENWELL;
> > + else
> > + mrst_cpu_chip = MRST_CPU_CHIP_LINCROFT;
>
>
> > + pr_debug("cpuid result %x\n", regs[CR_EAX]);
> > + pr_info("Moorestown CPU %s identified\n",
> > + (mrst_cpu_chip == MRST_CPU_CHIP_LINCROFT) ?
> > + "Lincroft" : "Penwell");
>
> Are we going to add one of those for each new family ? This is
> really redundant bloat with no value.
>
> > + return mrst_cpu_chip;
> > +}
> > +
> > /*
> > * Moorestown specific x86_init function overrides and early setup
> > * calls.
> > @@ -237,4 +330,6 @@ void __init x86_mrst_early_setup(void)
> > x86_init.pci.fixup_irqs = x86_init_noop;
> >
> > legacy_pic = &null_legacy_pic;
> > +
> > + mrst_identify_cpu();
> > }
> > --
> > 1.6.3.3
> >

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