x86, mrst: add more timer config options

Always-on local APIC timer (ARAT) has been introduced to Medfield, along
with the platform APB timers we have more timer configuration options
between Moorestown and Medfield.

This patch adds run-time detection of avaiable timer features so that
we can treat Medfield as a variant of Moorestown and set up the optimal
timer options for each platform. i.e.

Medfield: per cpu always-on local APIC timer
Moorestown: per cpu APB timer

Manual override is possible via cmdline option x86_mrst_timer.

Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
LKML-Reference: <1274295685-6774-4-git-send-email-jacob.jun.pan@linux.intel.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

1 files changed, 63 insertions, 25 deletions

diff --git a/arch/x86/kernel/mrst.c b/arch/x86/kernel/mrst.c
index ceaebeb5866f..636b53bd4198 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 int mrst_cpu_chip;
@@ -169,18 +192,6 @@ 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();
-        apbt_setup_secondary_clock();
-}
-
 static unsigned long __init mrst_calibrate_tsc(void)
 {
         unsigned long flags, fast_calibrate;
@@ -197,6 +208,21 @@ static unsigned long __init mrst_calibrate_tsc(void)
 
 void __init mrst_time_init(void)
 {
+        switch (mrst_timer_options) {
+        case MRST_TIMER_APBT_ONLY:
+                break;
+        case MRST_TIMER_LAPIC_APBT:
+                x86_init.timers.setup_percpu_clockev = setup_boot_APIC_clock;
+                x86_cpuinit.setup_percpu_clockev = setup_secondary_APIC_clock;
+                break;
+        default:
+                if (!boot_cpu_has(X86_FEATURE_ARAT))
+                        break;
+                x86_init.timers.setup_percpu_clockev = setup_boot_APIC_clock;
+                x86_cpuinit.setup_percpu_clockev = setup_secondary_APIC_clock;
+                return;
+        }
+        /* we need at least one APB timer */
         sfi_table_parse(SFI_SIG_MTMR, NULL, NULL, sfi_parse_mtmr);
         pre_init_apic_IRQ0();
         apbt_time_init();
@@ -207,17 +233,6 @@ void __init mrst_rtc_init(void)
         sfi_table_parse(SFI_SIG_MRTC, NULL, NULL, sfi_parse_mrtc);
 }
 
-/*
- * if we use per cpu apb timer, the bootclock already setup. if we use lapic
- * timer and one apbt timer for broadcast, we need to set up lapic boot clock.
- */
-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)
-                setup_boot_APIC_clock();
-};
-
 int mrst_identify_cpu(void)
 {
         return mrst_cpu_chip;
@@ -250,13 +265,13 @@ void __init x86_mrst_early_setup(void)
         x86_init.resources.reserve_resources = x86_init_noop;
 
         x86_init.timers.timer_init = mrst_time_init;
-        x86_init.timers.setup_percpu_clockev = mrst_setup_boot_clock;
+        x86_init.timers.setup_percpu_clockev = x86_init_noop;
 
         x86_init.irqs.pre_vector_init = x86_init_noop;
 
         x86_init.oem.arch_setup = mrst_arch_setup;
 
-        x86_cpuinit.setup_percpu_clockev = mrst_setup_secondary_clock;
+        x86_cpuinit.setup_percpu_clockev = apbt_setup_secondary_clock;
 
         x86_platform.calibrate_tsc = mrst_calibrate_tsc;
         x86_init.pci.init = pci_mrst_init;
@@ -269,3 +284,26 @@ void __init x86_mrst_early_setup(void)
         x86_init.mpparse.get_smp_config = x86_init_uint_noop;
 
 }
+
+/*
+ * if user does not want to use per CPU apb timer, just give it a lower rating
+ * than local apic timer and skip the late per cpu timer init.
+ */
+static inline int __init setup_x86_mrst_timer(char *arg)
+{
+        if (!arg)
+                return -EINVAL;
+
+        if (strcmp("apbt_only", arg) == 0)
+                mrst_timer_options = MRST_TIMER_APBT_ONLY;
+        else if (strcmp("lapic_and_apbt", arg) == 0)
+                mrst_timer_options = MRST_TIMER_LAPIC_APBT;
+        else {
+                pr_warning("X86 MRST timer option %s not recognised"
+                           " use x86_mrst_timer=apbt_only or lapic_and_apbt\n",
+                           arg);
+                return -EINVAL;
+        }
+        return 0;
+}
+__setup("x86_mrst_timer=", setup_x86_mrst_timer);