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From: Jacob Pan on 14 May 2010 18:00
Medfield has added always-on lapic timer which will be ranked higher
than the platform timers. This patch allows more timer options to
support optimal configuration for both Moorestown and Medfield.

i.e. per CPU always-on lapic timers for Medfield
per CPU APB timers for Moorestown

Signed-off-by: Jacob Pan <jacob.jun.pan(a)linux.intel.com>
---
arch/x86/include/asm/mrst.h | 7 ++++++
arch/x86/kernel/mrst.c | 51 +++++++++++++++++++++++++++++++++++-------
2 files changed, 49 insertions(+), 9 deletions(-)

diff --git a/arch/x86/include/asm/mrst.h b/arch/x86/include/asm/mrst.h
index ddf0ad8..f683603 100644
--- a/arch/x86/include/asm/mrst.h
+++ b/arch/x86/include/asm/mrst.h
@@ -12,6 +12,7 @@
#define _ASM_X86_MRST_H
extern int pci_mrst_init(void);
extern int mrst_identify_cpu(void);
+extern int mrst_timer_options __cpuinitdata;
int __init sfi_parse_mrtc(struct sfi_table_header *table);

/**
@@ -26,6 +27,12 @@ enum mrst_cpu_type {
MRST_CPU_CHIP_PENWELL,
};

+enum mrst_timer_options {
+ MRST_TIMER_DEFAULT,
+ MRST_TIMER_APBT_ONLY,
+ MRST_TIMER_LAPIC_APBT,
+};
+
#define SFI_MTMR_MAX_NUM 8
#define SFI_MRTC_MAX 8

diff --git a/arch/x86/kernel/mrst.c b/arch/x86/kernel/mrst.c
index a3e85be..339d7f5 100644
--- a/arch/x86/kernel/mrst.c
+++ b/arch/x86/kernel/mrst.c
@@ -25,6 +25,29 @@
#include <asm/i8259.h>
#include <asm/apb_timer.h>

+/**
+ * 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
+ * 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;
@@ -168,15 +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;
+ }
apbt_setup_secondary_clock();
}

@@ -196,6 +220,13 @@ static unsigned long __init mrst_calibrate_tsc(void)

void __init mrst_time_init(void)
{
+ mrst_identify_cpu();
+
+ /* 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();
@@ -212,8 +243,10 @@ 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();
};

--
1.6.3.3

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Prev: [PATCH 7/8] x86/mrst: add nop functions to x86_init mpparse functions
Next: [PATCH 2/8] x86/mrst: add cpu type detection for Medfield