[PATCH 7/8] x86/apbt: Moorestown APB system timer driver
From: Jacob Pan
Date: Wed Sep 02 2009 - 10:37:17 EST
Signed-off-by: Jacob Pan <jacob.jun.pan@xxxxxxxxx>
---
Documentation/kernel-parameters.txt | 6 +
arch/x86/Kconfig | 11 +
arch/x86/include/asm/apb_timer.h | 70 ++++
arch/x86/kernel/Makefile | 2 +-
arch/x86/kernel/apb_timer.c | 780 +++++++++++++++++++++++++++++++++++
5 files changed, 868 insertions(+), 1 deletions(-)
create mode 100644 arch/x86/include/asm/apb_timer.h
create mode 100644 arch/x86/kernel/apb_timer.c
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 736d456..c3e69a0 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1729,6 +1729,12 @@ and is between 256 and 4096 characters. It is defined in the file
nomfgpt [X86-32] Disable Multi-Function General Purpose
Timer usage (for AMD Geode machines).
+ x86_mrst_timer [X86-32,APBT]
+ choose timer option for x86 moorestown mid platform.
+ two valid options are apbt timer only and lapic timer
+ plus one apbt timer for broadcast timer.
+ x86_mrst_timer=apbt_only | lapic_and_apbt
+
norandmaps Don't use address space randomization. Equivalent to
echo 0 > /proc/sys/kernel/randomize_va_space
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index eb40925..d3a0d9f 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -390,6 +390,7 @@ config X86_MRST
bool "Moorestown MID platform"
depends on X86_32
depends on X86_EXTENDED_PLATFORM
+ select APB_TIMER
---help---
Moorestown is Intel's Low Power Intel Architecture (LPIA) based Moblin
Internet Device(MID) platform. Moorestown consists of two chips:
@@ -612,6 +613,16 @@ config HPET_EMULATE_RTC
def_bool y
depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
+config APB_TIMER
+ def_bool y if MRST
+ prompt "Langwell APB Timer Support" if X86_MRST
+ help
+ APB timer is the replacement for 8254, HPET on X86 MID platforms.
+ The APBT provides a stable time base on SMP
+ systems, unlike the TSC, but it is more expensive to access,
+ as it is off-chip. APB timers are always running regardless of CPU
+ C states, they are used as per CPU clockevent device when possible.
+
# Mark as embedded because too many people got it wrong.
# The code disables itself when not needed.
config DMI
diff --git a/arch/x86/include/asm/apb_timer.h b/arch/x86/include/asm/apb_timer.h
new file mode 100644
index 0000000..643fb7f
--- /dev/null
+++ b/arch/x86/include/asm/apb_timer.h
@@ -0,0 +1,70 @@
+/*
+ * apb_timer.h: Driver for Langwell APB timer based on Synopsis DesignWare
+ *
+ * (C) Copyright 2009 Intel Corporation
+ * Author: Jacob Pan (jacob.jun.pan@xxxxxxxxx)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; version 2
+ * of the License.
+ *
+ * Note:
+ */
+
+#ifndef ASM_X86_APBT_H
+#define ASM_X86_APBT_H
+#include <linux/sfi.h>
+
+#ifdef CONFIG_APB_TIMER
+
+/* Langwell DW APB timer registers */
+#define APBTMR_N_LOAD_COUNT 0x00
+#define APBTMR_N_CURRENT_VALUE 0x04
+#define APBTMR_N_CONTROL 0x08
+#define APBTMR_N_EOI 0x0c
+#define APBTMR_N_INT_STATUS 0x10
+
+#define APBTMRS_INT_STATUS 0xa0
+#define APBTMRS_EOI 0xa4
+#define APBTMRS_RAW_INT_STATUS 0xa8
+#define APBTMRS_COMP_VERSION 0xac
+#define APBTMRS_REG_SIZE 0x14
+
+/* register bits */
+#define APBTMR_CONTROL_ENABLE (1<<0)
+#define APBTMR_CONTROL_MODE_PERIODIC (1<<1) /*1: periodic 0:free running */
+#define APBTMR_CONTROL_INT (1<<2)
+
+/* default memory mapped register base */
+#define LNW_SCU_ADDR 0xFF100000
+#define LNW_EXT_TIMER_OFFSET 0x1B800
+#define APBT_DEFAULT_BASE (LNW_SCU_ADDR+LNW_EXT_TIMER_OFFSET)
+#define LNW_EXT_TIMER_PGOFFSET 0x800
+
+/* APBT clock speed range from PCLK to fabric base, 25-100MHz */
+#define APBT_MAX_FREQ 50
+#define APBT_MIN_FREQ 1
+#define APBT_MMAP_SIZE 1024
+
+#define APBT_DEV_USED 1
+
+extern void apbt_time_init(void);
+extern struct clock_event_device *global_clock_event;
+extern unsigned long apbt_quick_calibrate(void);
+extern int arch_setup_apbt_irqs(int irq, int trigger, int mask, int cpu);
+extern void apbt_setup_secondary_clock(void);
+extern unsigned int boot_cpu_id;
+extern int disable_apbt_percpu;
+
+extern struct sfi_timer_table_entry *sfi_get_mtmr(int hint);
+extern void sfi_free_mtmr(struct sfi_timer_table_entry *mtmr);
+extern int sfi_mtimer_num;
+
+#else /* CONFIG_APB_TIMER */
+
+static inline unsigned long apbt_quick_calibrate(void) {return 0; }
+static inline void apbt_time_init(void) {return 0; }
+
+#endif
+#endif /* ASM_X86_APBT_H */
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index d87f09b..0ad9bc2 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -87,7 +87,7 @@ obj-$(CONFIG_VM86) += vm86_32.o
obj-$(CONFIG_EARLY_PRINTK) += early_printk.o
obj-$(CONFIG_HPET_TIMER) += hpet.o
-
+obj-$(CONFIG_APB_TIMER) += apb_timer.o
obj-$(CONFIG_K8_NB) += k8.o
obj-$(CONFIG_DEBUG_RODATA_TEST) += test_rodata.o
obj-$(CONFIG_DEBUG_NX_TEST) += test_nx.o
diff --git a/arch/x86/kernel/apb_timer.c b/arch/x86/kernel/apb_timer.c
new file mode 100644
index 0000000..35f4d5f
--- /dev/null
+++ b/arch/x86/kernel/apb_timer.c
@@ -0,0 +1,780 @@
+/*
+ * apb_timer.c: Driver for Langwell APB timers
+ *
+ * (C) Copyright 2009 Intel Corporation
+ * Author: Jacob Pan (jacob.jun.pan@xxxxxxxxx)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; version 2
+ * of the License.
+ *
+ * Note:
+ * Langwell is the south complex of Intel Moorestown MID platform. There are
+ * eight external timers in total that can be used by the operating system.
+ * The timer information, such as frequency and addresses, is provided to the
+ * OS via SFI tables.
+ * Timer interrupts are routed via FW/HW emulated IOAPIC independently via
+ * individual redirection table entries (RTE).
+ * Unlike HPET, there is no master counter, therefore one of the timers are
+ * used as clocksource. The overall allocation looks like:
+ * - timer 0 - NR_CPUs for per cpu timer
+ * - one timer for clocksource
+ * - one timer for watchdog driver.
+ * It is also worth notice that APB timer does not support true one-shot mode,
+ * free-running mode will be used here to emulate one-shot mode.
+ * APB timer can also be used as broadcast timer along with per cpu local APIC
+ * timer, but by default APB timer has higher rating than local APIC timers.
+ */
+
+#include <linux/clocksource.h>
+#include <linux/clockchips.h>
+#include <linux/delay.h>
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/sysdev.h>
+#include <linux/pm.h>
+#include <linux/pci.h>
+#include <linux/sfi.h>
+#include <linux/interrupt.h>
+#include <linux/cpu.h>
+#include <linux/irq.h>
+
+#include <asm/fixmap.h>
+#include <asm/apb_timer.h>
+
+#define APBT_MASK CLOCKSOURCE_MASK(32)
+#define APBT_SHIFT 22
+#define APBT_CLOCKEVENT_RATING 150
+#define APBT_CLOCKSOURCE_RATING 250
+#define APBT_MIN_DELTA_USEC 200
+
+#define EVT_TO_APBT_DEV(evt) container_of(evt, struct apbt_dev, evt)
+#define APBT_CLOCKEVENT0_NUM (0)
+#define APBT_CLOCKEVENT1_NUM (1)
+#define APBT_CLOCKSOURCE_NUM (2)
+
+static unsigned long apbt_address;
+static int apb_timer_block_enabled;
+static void __iomem *apbt_virt_address;
+static int phy_cs_timer_id;
+
+/*
+ * Common DW APB timer info
+ */
+static uint64_t apbt_freq;
+
+static void apbt_set_mode(enum clock_event_mode mode,
+ struct clock_event_device *evt);
+static int apbt_next_event(unsigned long delta,
+ struct clock_event_device *evt);
+static cycle_t apbt_read_clocksource(struct clocksource *cs);
+static void apbt_restart_clocksource(void);
+
+struct apbt_dev {
+ struct clock_event_device evt;
+ unsigned int num;
+ int cpu;
+ unsigned int irq;
+ unsigned int tick;
+ unsigned int count;
+ unsigned int flags;
+ char name[10];
+};
+
+int disable_apbt_percpu __cpuinitdata;
+
+#ifdef CONFIG_SMP
+static unsigned int apbt_num_timers_used;
+static DEFINE_PER_CPU(struct apbt_dev, cpu_apbt_dev);
+static struct apbt_dev *apbt_devs;
+#endif
+
+static inline unsigned long apbt_readl_reg(unsigned long a)
+{
+ return readl(apbt_virt_address + a);
+}
+
+static inline void apbt_writel_reg(unsigned long d, unsigned long a)
+{
+ writel(d, apbt_virt_address + a);
+}
+
+static inline unsigned long apbt_readl(int n, unsigned long a)
+{
+ return readl(apbt_virt_address + a + n * APBTMRS_REG_SIZE);
+}
+
+static inline void apbt_writel(int n, unsigned long d, unsigned long a)
+{
+ writel(d, apbt_virt_address + a + n * APBTMRS_REG_SIZE);
+}
+
+static inline void apbt_set_mapping(void)
+{
+ struct sfi_timer_table_entry *mtmr;
+
+ if (apbt_virt_address) {
+ pr_debug("APBT base already mapped\n");
+ return;
+ }
+ mtmr = sfi_get_mtmr(APBT_CLOCKEVENT0_NUM);
+ if (mtmr == NULL) {
+ printk(KERN_ERR "Failed to get MTMR %d from SFI\n",
+ APBT_CLOCKEVENT0_NUM);
+ return;
+ }
+ apbt_address = (unsigned long)mtmr->phys_addr;
+ if (!apbt_address) {
+ printk(KERN_WARNING "No timer base from SFI, use default\n");
+ apbt_address = APBT_DEFAULT_BASE;
+ }
+ apbt_virt_address = ioremap_nocache(apbt_address, APBT_MMAP_SIZE);
+ if (apbt_virt_address) {
+ pr_debug("Mapped APBT physical addr %p at virtual addr %p\n",\
+ (void *)apbt_address, (void *)apbt_virt_address);
+ } else {
+ pr_debug("Failed mapping APBT phy address at %p\n",\
+ (void *)apbt_address);
+ goto panic_noapbt;
+ }
+ apbt_freq = mtmr->freq_hz / USEC_PER_SEC;
+ sfi_free_mtmr(mtmr);
+
+ /* Now figure out the physical timer id for clocksource device */
+ mtmr = sfi_get_mtmr(APBT_CLOCKSOURCE_NUM);
+ if (mtmr == NULL)
+ goto panic_noapbt;
+
+ /* Now figure out the physical timer id */
+ phy_cs_timer_id = (unsigned int)(mtmr->phys_addr & 0xff)
+ / APBTMRS_REG_SIZE;
+ pr_debug("Use timer %d for clocksource\n", phy_cs_timer_id);
+ return;
+
+panic_noapbt:
+ panic("Failed to setup APB system timer\n");
+
+}
+
+static inline void apbt_clear_mapping(void)
+{
+ iounmap(apbt_virt_address);
+ apbt_virt_address = NULL;
+}
+
+/*
+ * APBT timer interrupt enable / disable
+ */
+static inline int is_apbt_capable(void)
+{
+ return apbt_virt_address ? 1 : 0;
+}
+
+static struct clocksource clocksource_apbt = {
+ .name = "apbt",
+ .rating = APBT_CLOCKSOURCE_RATING,
+ .read = apbt_read_clocksource,
+ .mask = APBT_MASK,
+ .shift = APBT_SHIFT,
+ .flags = CLOCK_SOURCE_IS_CONTINUOUS,
+ .resume = apbt_restart_clocksource,
+};
+
+/* boot APB clock event device */
+static struct clock_event_device apbt_clockevent = {
+ .name = "apbt0",
+ .features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
+ .set_mode = apbt_set_mode,
+ .set_next_event = apbt_next_event,
+ .shift = APBT_SHIFT,
+ .irq = 0,
+ .rating = APBT_CLOCKEVENT_RATING,
+};
+
+/*
+ * 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)
+ disable_apbt_percpu = 0;
+ else if (strcmp("lapic_and_apbt", arg) == 0)
+ disable_apbt_percpu = 1;
+ 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);
+
+/*
+ * start count down from 0xffff_ffff. this is done by toggling the enable bit
+ * then load initial load count to ~0.
+ */
+static void apbt_start_counter(int n)
+{
+ unsigned long ctrl = apbt_readl(n, APBTMR_N_CONTROL);
+
+ ctrl &= ~APBTMR_CONTROL_ENABLE;
+ apbt_writel(n, ctrl, APBTMR_N_CONTROL);
+ apbt_writel(n, ~0, APBTMR_N_LOAD_COUNT);
+ /* enable, mask interrupt */
+ ctrl &= ~APBTMR_CONTROL_MODE_PERIODIC;
+ ctrl |= (APBTMR_CONTROL_ENABLE | APBTMR_CONTROL_INT);
+ apbt_writel(n, ctrl, APBTMR_N_CONTROL);
+ /* read it once to get cached counter value initialized */
+ apbt_read_clocksource(&clocksource_apbt);
+}
+
+static irqreturn_t apbt_interrupt_handler(int irq, void *data)
+{
+ struct apbt_dev *dev = (struct apbt_dev *)data;
+ struct clock_event_device *aevt = &dev->evt;
+
+ if (!aevt->event_handler) {
+ printk(KERN_INFO "Spurious APBT timer interrupt on %d\n",
+ dev->num);
+ return IRQ_NONE;
+ }
+ aevt->event_handler(aevt);
+ return IRQ_HANDLED;
+}
+
+static void apbt_restart_clocksource(void)
+{
+ apbt_start_counter(phy_cs_timer_id);
+}
+
+/* Setup IRQ routing via IOAPIC */
+#ifdef CONFIG_SMP
+static void apbt_setup_irq(struct apbt_dev *adev)
+{
+ struct irq_chip *chip;
+ struct irq_desc *desc;
+
+ /* timer0 irq has been setup early */
+ if (adev->irq == 0)
+ return;
+ desc = irq_to_desc(adev->irq);
+ chip = get_irq_chip(adev->irq);
+ disable_irq(adev->irq);
+ desc->status |= IRQ_MOVE_PCNTXT;
+ irq_set_affinity(adev->irq, cpumask_of(adev->cpu));
+ /* APB timer irqs are set up as mp_irqs, timer is edge triggerred */
+ set_irq_chip_and_handler_name(adev->irq, chip, handle_edge_irq, "edge");
+ enable_irq(adev->irq);
+ if (system_state == SYSTEM_BOOTING)
+ if (request_irq(adev->irq, apbt_interrupt_handler,
+ IRQF_TIMER | IRQF_DISABLED | IRQF_NOBALANCING,
+ adev->name, adev)) {
+ printk(KERN_ERR "Failed request IRQ for APBT%d\n",
+ adev->num);
+ }
+}
+#endif
+
+static void apbt_enable_int(int n)
+{
+ unsigned long ctrl = apbt_readl(n, APBTMR_N_CONTROL);
+ /* clear pending intr */
+ apbt_readl(n, APBTMR_N_EOI);
+ ctrl &= ~APBTMR_CONTROL_INT;
+ apbt_writel(n, ctrl, APBTMR_N_CONTROL);
+}
+
+static void apbt_disable_int(int n)
+{
+ unsigned long ctrl = apbt_readl(n, APBTMR_N_CONTROL);
+
+ ctrl |= APBTMR_CONTROL_INT;
+ apbt_writel(n, ctrl, APBTMR_N_CONTROL);
+}
+
+
+static int apbt_clockevent_register(void)
+{
+ struct sfi_timer_table_entry *mtmr;
+
+ mtmr = sfi_get_mtmr(APBT_CLOCKEVENT0_NUM);
+ if (mtmr == NULL) {
+ printk(KERN_ERR "Failed to get MTMR %d from SFI\n",
+ APBT_CLOCKEVENT0_NUM);
+ return -ENODEV;
+ }
+
+ /*
+ * We need to calculate the scaled math multiplication factor for
+ * nanosecond to apbt tick conversion.
+ * mult = (nsec/cycle)*2^APBT_SHIFT
+ */
+ apbt_clockevent.mult = div_sc((unsigned long) mtmr->freq_hz
+ , NSEC_PER_SEC, APBT_SHIFT);
+
+ /* Calculate the min / max delta */
+ apbt_clockevent.max_delta_ns = clockevent_delta2ns(0x7FFFFFFF,
+ &apbt_clockevent);
+ apbt_clockevent.min_delta_ns = clockevent_delta2ns(
+ APBT_MIN_DELTA_USEC*apbt_freq,
+ &apbt_clockevent);
+ /*
+ * Start apbt with the boot cpu mask and make it
+ * global if not used for per cpu timer.
+ */
+ apbt_clockevent.cpumask = cpumask_of(smp_processor_id());
+
+ if (disable_apbt_percpu) {
+ apbt_clockevent.rating = APBT_CLOCKEVENT_RATING - 100;
+ global_clock_event = &apbt_clockevent;
+ printk(KERN_DEBUG "%s clockevent registered as global\n",
+ global_clock_event->name);
+ }
+
+ if (request_irq(apbt_clockevent.irq, apbt_interrupt_handler,
+ IRQF_TIMER | IRQF_DISABLED | IRQF_NOBALANCING,
+ apbt_clockevent.name, &apbt_clockevent)) {
+ printk(KERN_ERR "Failed request IRQ for APBT%d\n",
+ apbt_clockevent.irq);
+ }
+
+ clockevents_register_device(&apbt_clockevent);
+ /* Start APBT 0 interrupts */
+ apbt_enable_int(APBT_CLOCKEVENT0_NUM);
+
+ sfi_free_mtmr(mtmr);
+ return 0;
+}
+
+#ifdef CONFIG_SMP
+/* Should be called with per cpu */
+void apbt_setup_secondary_clock(void)
+{
+ struct apbt_dev *adev;
+ struct clock_event_device *aevt;
+ int cpu;
+
+ /* Don't register boot CPU clockevent */
+ cpu = smp_processor_id();
+ if (cpu == boot_cpu_id)
+ return;
+ /*
+ * We need to calculate the scaled math multiplication factor for
+ * nanosecond to apbt tick conversion.
+ * mult = (nsec/cycle)*2^APBT_SHIFT
+ */
+ printk(KERN_INFO "Init per CPU clockevent %d\n", cpu);
+ adev = &per_cpu(cpu_apbt_dev, cpu);
+ aevt = &adev->evt;
+
+ memcpy(aevt, &apbt_clockevent, sizeof(*aevt));
+ aevt->cpumask = cpumask_of(cpu);
+ aevt->name = adev->name;
+ aevt->mode = CLOCK_EVT_MODE_UNUSED;
+
+ printk(KERN_INFO "Registering CPU %d clockevent device %s, mask %08x\n",
+ cpu, aevt->name, *(u32 *)aevt->cpumask);
+
+ apbt_setup_irq(adev);
+
+ clockevents_register_device(aevt);
+
+ apbt_enable_int(cpu);
+
+ return;
+}
+
+/*
+ * this notify handler process CPU hotplug events. in case of S0i3, nonboot
+ * cpus are disabled/enabled frequently, for performance reasons, we keep the
+ * per cpu timer irq registered so that we do need to do free_irq/request_irq.
+ *
+ * TODO: it might be more reliable to directly disable percpu clockevent device
+ * without the notifier chain. currently, cpu 0 may get interrupts from other
+ * cpu timers during the offline process due to the ordering of notification.
+ * the extra interrupt is harmless.
+ */
+static int apbt_cpuhp_notify(struct notifier_block *n,
+ unsigned long action, void *hcpu)
+{
+ unsigned long cpu = (unsigned long)hcpu;
+ struct apbt_dev *adev = &per_cpu(cpu_apbt_dev, cpu);
+
+ switch (action & 0xf) {
+ case CPU_DEAD:
+ apbt_disable_int(cpu);
+ if (system_state == SYSTEM_RUNNING)
+ pr_debug("skipping APBT CPU %lu offline\n", cpu);
+ else if (adev) {
+ pr_debug("APBT clockevent for cpu %lu offline\n", cpu);
+ free_irq(adev->irq, adev);
+ }
+ break;
+ default:
+ pr_debug(KERN_INFO "APBT notified %lu, no action\n", action);
+ }
+ return NOTIFY_OK;
+}
+
+static __init int apbt_late_init(void)
+{
+ if (disable_apbt_percpu)
+ return 0;
+ /* This notifier should be called after workqueue is ready */
+ hotcpu_notifier(apbt_cpuhp_notify, -20);
+ return 0;
+}
+fs_initcall(apbt_late_init);
+#else
+
+void apbt_setup_secondary_clock(void) {}
+
+#endif /* CONFIG_SMP */
+
+static void apbt_set_mode(enum clock_event_mode mode,
+ struct clock_event_device *evt)
+{
+ unsigned long ctrl;
+ uint64_t delta;
+ int timer_num;
+ struct apbt_dev *adev = EVT_TO_APBT_DEV(evt);
+
+ timer_num = adev->num;
+ pr_debug("%s CPU %d timer %d mode=%d\n",
+ __func__, first_cpu(*evt->cpumask), timer_num, mode);
+
+ switch (mode) {
+ case CLOCK_EVT_MODE_PERIODIC:
+ delta = ((uint64_t)(NSEC_PER_SEC/HZ)) * apbt_clockevent.mult;
+ delta >>= apbt_clockevent.shift;
+ ctrl = apbt_readl(timer_num, APBTMR_N_CONTROL);
+ ctrl |= APBTMR_CONTROL_MODE_PERIODIC;
+ apbt_writel(timer_num, ctrl, APBTMR_N_CONTROL);
+ /*
+ * DW APB p. 46, have to disable timer before load counter,
+ * may cause sync problem.
+ */
+ ctrl &= ~APBTMR_CONTROL_ENABLE;
+ apbt_writel(timer_num, ctrl, APBTMR_N_CONTROL);
+ udelay(1);
+ pr_debug("Setting clock period %d for HZ %d\n", (int)delta, HZ);
+ apbt_writel(timer_num, delta, APBTMR_N_LOAD_COUNT);
+ ctrl |= APBTMR_CONTROL_ENABLE;
+ apbt_writel(timer_num, ctrl, APBTMR_N_CONTROL);
+ break;
+ /* APB timer does not have one-shot mode, use free running mode */
+ case CLOCK_EVT_MODE_ONESHOT:
+ ctrl = apbt_readl(timer_num, APBTMR_N_CONTROL);
+ /*
+ * set free running mode, this mode will let timer reload max
+ * timeout which will give time (3min on 25MHz clock) to rearm
+ * the next event, therefore emulate the one-shot mode.
+ */
+ ctrl &= ~APBTMR_CONTROL_ENABLE;
+ ctrl &= ~APBTMR_CONTROL_MODE_PERIODIC;
+
+ apbt_writel(timer_num, ctrl, APBTMR_N_CONTROL);
+ /* write again to set free running mode */
+ apbt_writel(timer_num, ctrl, APBTMR_N_CONTROL);
+
+ /*
+ * DW APB p. 46, load counter with all 1s before starting free
+ * running mode.
+ */
+ apbt_writel(timer_num, ~0, APBTMR_N_LOAD_COUNT);
+ ctrl &= ~APBTMR_CONTROL_INT;
+ ctrl |= APBTMR_CONTROL_ENABLE;
+ apbt_writel(timer_num, ctrl, APBTMR_N_CONTROL);
+ break;
+
+ case CLOCK_EVT_MODE_UNUSED:
+ case CLOCK_EVT_MODE_SHUTDOWN:
+ apbt_disable_int(timer_num);
+ ctrl = apbt_readl(timer_num, APBTMR_N_CONTROL);
+ ctrl &= ~APBTMR_CONTROL_ENABLE;
+ apbt_writel(timer_num, ctrl, APBTMR_N_CONTROL);
+ break;
+
+ case CLOCK_EVT_MODE_RESUME:
+ apbt_enable_int(timer_num);
+ break;
+ }
+}
+
+static int apbt_next_event(unsigned long delta,
+ struct clock_event_device *evt)
+{
+ unsigned long ctrl;
+ int timer_num;
+
+ struct apbt_dev *adev = EVT_TO_APBT_DEV(evt);
+
+ timer_num = adev->num;
+ /* Disable timer */
+ ctrl = apbt_readl(timer_num, APBTMR_N_CONTROL);
+ ctrl &= ~APBTMR_CONTROL_ENABLE;
+ apbt_writel(timer_num, ctrl, APBTMR_N_CONTROL);
+ /* write new count */
+ apbt_writel(timer_num, delta, APBTMR_N_LOAD_COUNT);
+ ctrl |= APBTMR_CONTROL_ENABLE;
+ apbt_writel(timer_num, ctrl, APBTMR_N_CONTROL);
+ return 0;
+}
+
+/*
+ * APB timer clock is not in sync with pclk on Langwell, which translates to
+ * unreliable read value caused by sampling error. the error does not add up
+ * overtime and only happens when sampling a 0 as a 1 by mistake. so the time
+ * would go backwards. the following code is trying to prevent time traveling
+ * backwards. little bit paranoid.
+ */
+static cycle_t apbt_read_clocksource(struct clocksource *cs)
+{
+ unsigned long t0, t1, t2;
+ static unsigned long last_read;
+
+bad_count:
+ t1 = apbt_readl(phy_cs_timer_id,
+ APBTMR_N_CURRENT_VALUE);
+ t2 = apbt_readl(phy_cs_timer_id,
+ APBTMR_N_CURRENT_VALUE);
+ if (unlikely(t1 < t2)) {
+ pr_debug("APBT: read current count error %lx:%lx:%lx\n",
+ t1, t2, t2 - t1);
+ goto bad_count;
+ }
+ /*
+ * check against cached last read, makes sure time does not go back.
+ * it could be a normal rollover but we will do tripple check anyway
+ */
+ if (unlikely(t2 > last_read)) {
+ /* check if we have a normal rollover */
+ unsigned long raw_intr_status =
+ apbt_readl_reg(APBTMRS_RAW_INT_STATUS);
+ /*
+ * cs timer interrupt is masked but raw intr bit is set if
+ * rollover occurs. then we read EOI reg to clear it.
+ */
+ if (raw_intr_status & (1 << phy_cs_timer_id)) {
+ apbt_readl(phy_cs_timer_id, APBTMR_N_EOI);
+ goto out;
+ }
+ pr_debug("APB CS going back %lx:%lx:%lx ",
+ t2, last_read, t2 - last_read);
+bad_count_x3:
+ pr_debug(KERN_INFO "tripple check enforced\n");
+ t0 = apbt_readl(phy_cs_timer_id,
+ APBTMR_N_CURRENT_VALUE);
+ udelay(1);
+ t1 = apbt_readl(phy_cs_timer_id,
+ APBTMR_N_CURRENT_VALUE);
+ udelay(1);
+ t2 = apbt_readl(phy_cs_timer_id,
+ APBTMR_N_CURRENT_VALUE);
+ if ((t2 > t1) || (t1 > t0)) {
+ printk(KERN_ERR "Error: APB CS tripple check failed\n");
+ goto bad_count_x3;
+ }
+ }
+out:
+ last_read = t2;
+ return (cycle_t)~t2;
+}
+
+static int apbt_clocksource_register(void)
+{
+ u64 start, now;
+ cycle_t t1;
+
+ /* Start the counter, use timer 2 as source, timer 0/1 for event */
+ apbt_start_counter(phy_cs_timer_id);
+
+ /* Verify whether apbt counter works */
+ t1 = apbt_read_clocksource(&clocksource_apbt);
+ rdtscll(start);
+
+ /*
+ * We don't know the TSC frequency yet, but waiting for
+ * 200000 TSC cycles is safe:
+ * 4 GHz == 50us
+ * 1 GHz == 200us
+ */
+ do {
+ rep_nop();
+ rdtscll(now);
+ } while ((now - start) < 200000UL);
+
+ /* APBT is the only always on clocksource, it has to work! */
+ if (t1 == apbt_read_clocksource(&clocksource_apbt))
+ panic("APBT counter not counting. APBT disabled\n");
+
+ /*
+ * initialize and register APBT clocksource
+ * convert that to ns/clock cycle
+ * mult = (ns/c) * 2^APBT_SHIFT
+ */
+ clocksource_apbt.mult = div_sc(MSEC_PER_SEC,
+ (unsigned long) apbt_freq, APBT_SHIFT);
+ clocksource_register(&clocksource_apbt);
+
+ return 0;
+}
+
+/*
+ * Early setup the APBT timer, only use timer 0 for booting then switch to
+ * per CPU timer if possible.
+ * returns 1 if per cpu apbt is setup
+ * returns 0 if no per cpu apbt is chosen
+ * panic if set up failed, this is the only platform timer on Moorestown.
+ */
+void __init apbt_time_init(void)
+{
+#ifdef CONFIG_SMP
+ int i;
+ struct sfi_timer_table_entry *p_mtmr;
+ unsigned int percpu_timer;
+ struct apbt_dev *adev;
+#endif
+
+ if (apb_timer_block_enabled)
+ return;
+ apbt_set_mapping();
+ if (apbt_virt_address) {
+ pr_debug("Found APBT version 0x%lx\n",\
+ apbt_readl_reg(APBTMRS_COMP_VERSION));
+ } else
+ goto out_noapbt;
+ /*
+ * Read the frequency and check for a sane value, for ESL model
+ * we extend the possible clock range to allow time scaling.
+ */
+
+ if (apbt_freq < APBT_MIN_FREQ || apbt_freq > APBT_MAX_FREQ) {
+ pr_debug("APBT has invalid freq 0x%llx\n", apbt_freq);
+ goto out_noapbt;
+ }
+ if (apbt_clocksource_register()) {
+ pr_debug("APBT has failed to register clocksource\n");
+ goto out_noapbt;
+ }
+ if (!apbt_clockevent_register())
+ apb_timer_block_enabled = 1;
+ else {
+ pr_debug("APBT has failed to register clockevent\n");
+ goto out_noapbt;
+ }
+#ifdef CONFIG_SMP
+ /* kernel cmdline disable apb timer, so we will use lapic timers */
+ if (disable_apbt_percpu) {
+ printk(KERN_INFO "apbt: disabled per cpu timer\n");
+ return;
+ }
+ pr_debug("%s: %d CPUs online\n", __func__, num_online_cpus());
+ if (num_possible_cpus() <= sfi_mtimer_num) {
+ percpu_timer = 1;
+ apbt_num_timers_used = num_possible_cpus();
+ } else {
+ percpu_timer = 0;
+ apbt_num_timers_used = 1;
+ adev = &per_cpu(cpu_apbt_dev, 0);
+ adev->flags &= ~APBT_DEV_USED;
+ }
+ pr_debug("%s: %d APB timers used\n", __func__, apbt_num_timers_used);
+
+ /* here we set up per CPU timer data structure */
+ apbt_devs = kzalloc(sizeof(struct apbt_dev) * apbt_num_timers_used,
+ GFP_KERNEL);
+ if (!apbt_devs) {
+ printk(KERN_ERR "Failed to allocate APB timer devices\n");
+ return;
+ }
+ for (i = 0; i < apbt_num_timers_used; i++) {
+ adev = &per_cpu(cpu_apbt_dev, i);
+ adev->num = i;
+ adev->cpu = i;
+ p_mtmr = sfi_get_mtmr(i);
+ if (p_mtmr) {
+ adev->tick = p_mtmr->freq_hz;
+ adev->irq = p_mtmr->irq;
+ } else
+ printk(KERN_ERR "Failed to get timer for cpu %d\n", i);
+ adev->count = 0;
+ sprintf(adev->name, "apbt%d", i);
+ }
+#endif
+
+ return;
+
+out_noapbt:
+ apbt_clear_mapping();
+ apb_timer_block_enabled = 0;
+ panic("failed to enable APB timer\n");
+}
+
+static inline void apbt_disable(int n)
+{
+ if (is_apbt_capable()) {
+ unsigned long ctrl = apbt_readl(n, APBTMR_N_CONTROL);
+ ctrl &= ~APBTMR_CONTROL_ENABLE;
+ apbt_writel(n, ctrl, APBTMR_N_CONTROL);
+ }
+}
+
+/* called before apb_timer_enable, use early map */
+unsigned long apbt_quick_calibrate()
+{
+ int i, scale;
+ u64 old, new;
+ cycle_t t1, t2;
+ unsigned long khz = 0;
+ u32 loop, shift;
+
+ apbt_set_mapping();
+ apbt_start_counter(phy_cs_timer_id);
+
+ /* check if the timer can count down, otherwise return */
+ old = apbt_read_clocksource(&clocksource_apbt);
+ i = 10000;
+ while (--i) {
+ if (old != apbt_read_clocksource(&clocksource_apbt))
+ break;
+ }
+ if (!i)
+ goto failed;
+
+ /* count 16 ms */
+ loop = (apbt_freq * 1000) << 4;
+
+ /* restart the timer to ensure it won't get to 0 in the calibration */
+ apbt_start_counter(phy_cs_timer_id);
+
+ old = apbt_read_clocksource(&clocksource_apbt);
+ old += loop;
+
+ t1 = __native_read_tsc();
+
+ do {
+ new = apbt_read_clocksource(&clocksource_apbt);
+ } while (new < old);
+
+ t2 = __native_read_tsc();
+
+ shift = 5;
+ if (unlikely(loop >> shift == 0)) {
+ printk(KERN_INFO
+ "APBT TSC calibration failed, not enough resolution\n");
+ return 0;
+ }
+ scale = (int)div_u64((t2 - t1), loop >> shift);
+ khz = (scale * apbt_freq * 1000) >> shift;
+ printk(KERN_INFO "TSC freq calculated by APB timer is %lu khz\n", khz);
+ return khz;
+failed:
+ return 0;
+}
--
1.6.5.3
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