[PATCH] 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.

lapic timer calibration can be combined with tsc in platform specific
calibration functions. if such calibration result is obtained early,
we can skip the redundent calibration loops.

Signed-off-by: Alek Du <alek.du@xxxxxxxxx>
Signed-off-by: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
---
arch/x86/include/asm/apic.h | 1 +
arch/x86/include/asm/processor.h | 3 +++
arch/x86/kernel/apic/apic.c | 33 ++++++++++++++++++++++++++-------
arch/x86/kernel/cpu/intel.c | 34 ++++++++++++++++++++++++++++++++++
arch/x86/kernel/mrst.c | 32 ++++++++++++++++++++++++--------
5 files changed, 88 insertions(+), 15 deletions(-)

diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h
index 1fa03e0..448c763 100644
--- a/arch/x86/include/asm/apic.h
+++ b/arch/x86/include/asm/apic.h
@@ -50,6 +50,7 @@ extern unsigned int apic_verbosity;
extern int local_apic_timer_c2_ok;

extern int disable_apic;
+extern unsigned int lapic_timer_frequency;

#ifdef CONFIG_SMP
extern void __inquire_remote_apic(int apicid);
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/apic/apic.c b/arch/x86/kernel/apic/apic.c
index e5a4a1e..2141ff5 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -175,7 +175,7 @@ static struct resource lapic_resource = {
.flags = IORESOURCE_MEM | IORESOURCE_BUSY,
};

-static unsigned int calibration_result;
+unsigned int lapic_timer_frequency;

static int lapic_next_event(unsigned long delta,
struct clock_event_device *evt);
@@ -430,7 +430,7 @@ static void lapic_timer_setup(enum clock_event_mode mode,
switch (mode) {
case CLOCK_EVT_MODE_PERIODIC:
case CLOCK_EVT_MODE_ONESHOT:
- __setup_APIC_LVTT(calibration_result,
+ __setup_APIC_LVTT(lapic_timer_frequency,
mode != CLOCK_EVT_MODE_PERIODIC, 1);
break;
case CLOCK_EVT_MODE_UNUSED:
@@ -597,6 +597,25 @@ static int __init calibrate_APIC_clock(void)
long delta, deltatsc;
int pm_referenced = 0;

+ /**
+ * check if lapic timer has already been calibrated by platform
+ * specific routine, such as tsc calibration code. if so, we just fill
+ * in the clockevent structure and return.
+ */
+
+ if (lapic_timer_frequency) {
+ apic_printk(APIC_VERBOSE, "lapic timer already calibrated %d\n",
+ lapic_timer_frequency);
+ lapic_clockevent.mult = div_sc(lapic_timer_frequency/APIC_DIVISOR,
+ TICK_NSEC, lapic_clockevent.shift);
+ lapic_clockevent.max_delta_ns =
+ clockevent_delta2ns(0x7FFFFF, &lapic_clockevent);
+ lapic_clockevent.min_delta_ns =
+ clockevent_delta2ns(0xF, &lapic_clockevent);
+ lapic_clockevent.features &= ~CLOCK_EVT_FEAT_DUMMY;
+ return 0;
+ }
+
local_irq_disable();

/* Replace the global interrupt handler */
@@ -638,12 +657,12 @@ static int __init calibrate_APIC_clock(void)
lapic_clockevent.min_delta_ns =
clockevent_delta2ns(0xF, &lapic_clockevent);

- calibration_result = (delta * APIC_DIVISOR) / LAPIC_CAL_LOOPS;
+ lapic_timer_frequency = (delta * APIC_DIVISOR) / LAPIC_CAL_LOOPS;

apic_printk(APIC_VERBOSE, "..... delta %ld\n", delta);
apic_printk(APIC_VERBOSE, "..... mult: %u\n", lapic_clockevent.mult);
apic_printk(APIC_VERBOSE, "..... calibration result: %u\n",
- calibration_result);
+ lapic_timer_frequency);

if (cpu_has_tsc) {
apic_printk(APIC_VERBOSE, "..... CPU clock speed is "
@@ -654,13 +673,13 @@ static int __init calibrate_APIC_clock(void)

apic_printk(APIC_VERBOSE, "..... host bus clock speed is "
"%u.%04u MHz.\n",
- calibration_result / (1000000 / HZ),
- calibration_result % (1000000 / HZ));
+ lapic_timer_frequency / (1000000 / HZ),
+ lapic_timer_frequency % (1000000 / HZ));

/*
* Do a sanity check on the APIC calibration result
*/
- if (calibration_result < (1000000 / HZ)) {
+ if (lapic_timer_frequency < (1000000 / HZ)) {
local_irq_enable();
pr_warning("APIC frequency too slow, disabling apic timer\n");
return -1;
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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