diff options
Diffstat (limited to 'arch/x86/kernel/apb_timer.c')
| -rw-r--r-- | arch/x86/kernel/apb_timer.c | 784 |
1 files changed, 784 insertions, 0 deletions
diff --git a/arch/x86/kernel/apb_timer.c b/arch/x86/kernel/apb_timer.c new file mode 100644 index 000000000000..4b7099526d2c --- /dev/null +++ b/arch/x86/kernel/apb_timer.c @@ -0,0 +1,784 @@ +/* + * apb_timer.c: Driver for Langwell APB timers + * + * (C) Copyright 2009 Intel Corporation + * Author: Jacob Pan (jacob.jun.pan@intel.com) + * + * 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(struct clocksource *cs); + +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; + +static DEFINE_PER_CPU(struct apbt_dev, cpu_apbt_dev); + +#ifdef CONFIG_SMP +static unsigned int apbt_num_timers_used; +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(struct clocksource *cs) +{ + 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 __init apbt_clockevent_register(void) +{ + struct sfi_timer_table_entry *mtmr; + struct apbt_dev *adev = &__get_cpu_var(cpu_apbt_dev); + + 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()); + adev->num = smp_processor_id(); + memcpy(&adev->evt, &apbt_clockevent, sizeof(struct clock_event_device)); + + if (disable_apbt_percpu) { + apbt_clockevent.rating = APBT_CLOCKEVENT_RATING - 100; + global_clock_event = &adev->evt; + 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, adev)) { + printk(KERN_ERR "Failed request IRQ for APBT%d\n", + apbt_clockevent.irq); + } + + clockevents_register_device(&adev->evt); + /* 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; +} |