linux/arch/x86/kernel/hpet.c
Thomas Gleixner bb68cfe2f5 x86/hpet: Cure interface abuse in the resume path
The HPET resume path abuses irq_domain_[de]activate_irq() to restore the
MSI message in the HPET chip for the boot CPU on resume and it relies on an
implementation detail of the interrupt core code, which magically makes the
HPET unmask call invoked via a irq_disable/enable pair. This worked as long
as the irq code did unconditionally invoke the unmask() callback. With the
recent changes which keep track of the masked state to avoid expensive
hardware access, this does not longer work. As a consequence the HPET timer
interrupts are not unmasked which breaks resume as the boot CPU waits
forever that a timer interrupt arrives.

Make the restore of the MSI message explicit and invoke the unmask()
function directly. While at it get rid of the pointless affinity setting as
nothing can change the affinity of the interrupt and the vector across
suspend/resume. The restore of the MSI message reestablishes the previous
affinity setting which is the correct one.

Fixes: bf22ff45be ("genirq: Avoid unnecessary low level irq function calls")
Reported-and-tested-by: Tomi Sarvela <tomi.p.sarvela@intel.com>
Reported-by: Martin Peres <martin.peres@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Cc: jeffy.chen@rock-chips.com
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1707312158590.2287@nanos
2017-08-01 13:02:37 +02:00

1365 lines
32 KiB
C

#include <linux/clocksource.h>
#include <linux/clockchips.h>
#include <linux/interrupt.h>
#include <linux/export.h>
#include <linux/delay.h>
#include <linux/errno.h>
#include <linux/i8253.h>
#include <linux/slab.h>
#include <linux/hpet.h>
#include <linux/init.h>
#include <linux/cpu.h>
#include <linux/pm.h>
#include <linux/io.h>
#include <asm/cpufeature.h>
#include <asm/irqdomain.h>
#include <asm/fixmap.h>
#include <asm/hpet.h>
#include <asm/time.h>
#define HPET_MASK CLOCKSOURCE_MASK(32)
/* FSEC = 10^-15
NSEC = 10^-9 */
#define FSEC_PER_NSEC 1000000L
#define HPET_DEV_USED_BIT 2
#define HPET_DEV_USED (1 << HPET_DEV_USED_BIT)
#define HPET_DEV_VALID 0x8
#define HPET_DEV_FSB_CAP 0x1000
#define HPET_DEV_PERI_CAP 0x2000
#define HPET_MIN_CYCLES 128
#define HPET_MIN_PROG_DELTA (HPET_MIN_CYCLES + (HPET_MIN_CYCLES >> 1))
/*
* HPET address is set in acpi/boot.c, when an ACPI entry exists
*/
unsigned long hpet_address;
u8 hpet_blockid; /* OS timer block num */
bool hpet_msi_disable;
#ifdef CONFIG_PCI_MSI
static unsigned int hpet_num_timers;
#endif
static void __iomem *hpet_virt_address;
struct hpet_dev {
struct clock_event_device evt;
unsigned int num;
int cpu;
unsigned int irq;
unsigned int flags;
char name[10];
};
static inline struct hpet_dev *EVT_TO_HPET_DEV(struct clock_event_device *evtdev)
{
return container_of(evtdev, struct hpet_dev, evt);
}
inline unsigned int hpet_readl(unsigned int a)
{
return readl(hpet_virt_address + a);
}
static inline void hpet_writel(unsigned int d, unsigned int a)
{
writel(d, hpet_virt_address + a);
}
#ifdef CONFIG_X86_64
#include <asm/pgtable.h>
#endif
static inline void hpet_set_mapping(void)
{
hpet_virt_address = ioremap_nocache(hpet_address, HPET_MMAP_SIZE);
}
static inline void hpet_clear_mapping(void)
{
iounmap(hpet_virt_address);
hpet_virt_address = NULL;
}
/*
* HPET command line enable / disable
*/
bool boot_hpet_disable;
bool hpet_force_user;
static bool hpet_verbose;
static int __init hpet_setup(char *str)
{
while (str) {
char *next = strchr(str, ',');
if (next)
*next++ = 0;
if (!strncmp("disable", str, 7))
boot_hpet_disable = true;
if (!strncmp("force", str, 5))
hpet_force_user = true;
if (!strncmp("verbose", str, 7))
hpet_verbose = true;
str = next;
}
return 1;
}
__setup("hpet=", hpet_setup);
static int __init disable_hpet(char *str)
{
boot_hpet_disable = true;
return 1;
}
__setup("nohpet", disable_hpet);
static inline int is_hpet_capable(void)
{
return !boot_hpet_disable && hpet_address;
}
/*
* HPET timer interrupt enable / disable
*/
static bool hpet_legacy_int_enabled;
/**
* is_hpet_enabled - check whether the hpet timer interrupt is enabled
*/
int is_hpet_enabled(void)
{
return is_hpet_capable() && hpet_legacy_int_enabled;
}
EXPORT_SYMBOL_GPL(is_hpet_enabled);
static void _hpet_print_config(const char *function, int line)
{
u32 i, timers, l, h;
printk(KERN_INFO "hpet: %s(%d):\n", function, line);
l = hpet_readl(HPET_ID);
h = hpet_readl(HPET_PERIOD);
timers = ((l & HPET_ID_NUMBER) >> HPET_ID_NUMBER_SHIFT) + 1;
printk(KERN_INFO "hpet: ID: 0x%x, PERIOD: 0x%x\n", l, h);
l = hpet_readl(HPET_CFG);
h = hpet_readl(HPET_STATUS);
printk(KERN_INFO "hpet: CFG: 0x%x, STATUS: 0x%x\n", l, h);
l = hpet_readl(HPET_COUNTER);
h = hpet_readl(HPET_COUNTER+4);
printk(KERN_INFO "hpet: COUNTER_l: 0x%x, COUNTER_h: 0x%x\n", l, h);
for (i = 0; i < timers; i++) {
l = hpet_readl(HPET_Tn_CFG(i));
h = hpet_readl(HPET_Tn_CFG(i)+4);
printk(KERN_INFO "hpet: T%d: CFG_l: 0x%x, CFG_h: 0x%x\n",
i, l, h);
l = hpet_readl(HPET_Tn_CMP(i));
h = hpet_readl(HPET_Tn_CMP(i)+4);
printk(KERN_INFO "hpet: T%d: CMP_l: 0x%x, CMP_h: 0x%x\n",
i, l, h);
l = hpet_readl(HPET_Tn_ROUTE(i));
h = hpet_readl(HPET_Tn_ROUTE(i)+4);
printk(KERN_INFO "hpet: T%d ROUTE_l: 0x%x, ROUTE_h: 0x%x\n",
i, l, h);
}
}
#define hpet_print_config() \
do { \
if (hpet_verbose) \
_hpet_print_config(__func__, __LINE__); \
} while (0)
/*
* When the hpet driver (/dev/hpet) is enabled, we need to reserve
* timer 0 and timer 1 in case of RTC emulation.
*/
#ifdef CONFIG_HPET
static void hpet_reserve_msi_timers(struct hpet_data *hd);
static void hpet_reserve_platform_timers(unsigned int id)
{
struct hpet __iomem *hpet = hpet_virt_address;
struct hpet_timer __iomem *timer = &hpet->hpet_timers[2];
unsigned int nrtimers, i;
struct hpet_data hd;
nrtimers = ((id & HPET_ID_NUMBER) >> HPET_ID_NUMBER_SHIFT) + 1;
memset(&hd, 0, sizeof(hd));
hd.hd_phys_address = hpet_address;
hd.hd_address = hpet;
hd.hd_nirqs = nrtimers;
hpet_reserve_timer(&hd, 0);
#ifdef CONFIG_HPET_EMULATE_RTC
hpet_reserve_timer(&hd, 1);
#endif
/*
* NOTE that hd_irq[] reflects IOAPIC input pins (LEGACY_8254
* is wrong for i8259!) not the output IRQ. Many BIOS writers
* don't bother configuring *any* comparator interrupts.
*/
hd.hd_irq[0] = HPET_LEGACY_8254;
hd.hd_irq[1] = HPET_LEGACY_RTC;
for (i = 2; i < nrtimers; timer++, i++) {
hd.hd_irq[i] = (readl(&timer->hpet_config) &
Tn_INT_ROUTE_CNF_MASK) >> Tn_INT_ROUTE_CNF_SHIFT;
}
hpet_reserve_msi_timers(&hd);
hpet_alloc(&hd);
}
#else
static void hpet_reserve_platform_timers(unsigned int id) { }
#endif
/*
* Common hpet info
*/
static unsigned long hpet_freq;
static struct clock_event_device hpet_clockevent;
static void hpet_stop_counter(void)
{
u32 cfg = hpet_readl(HPET_CFG);
cfg &= ~HPET_CFG_ENABLE;
hpet_writel(cfg, HPET_CFG);
}
static void hpet_reset_counter(void)
{
hpet_writel(0, HPET_COUNTER);
hpet_writel(0, HPET_COUNTER + 4);
}
static void hpet_start_counter(void)
{
unsigned int cfg = hpet_readl(HPET_CFG);
cfg |= HPET_CFG_ENABLE;
hpet_writel(cfg, HPET_CFG);
}
static void hpet_restart_counter(void)
{
hpet_stop_counter();
hpet_reset_counter();
hpet_start_counter();
}
static void hpet_resume_device(void)
{
force_hpet_resume();
}
static void hpet_resume_counter(struct clocksource *cs)
{
hpet_resume_device();
hpet_restart_counter();
}
static void hpet_enable_legacy_int(void)
{
unsigned int cfg = hpet_readl(HPET_CFG);
cfg |= HPET_CFG_LEGACY;
hpet_writel(cfg, HPET_CFG);
hpet_legacy_int_enabled = true;
}
static void hpet_legacy_clockevent_register(void)
{
/* Start HPET legacy interrupts */
hpet_enable_legacy_int();
/*
* Start hpet with the boot cpu mask and make it
* global after the IO_APIC has been initialized.
*/
hpet_clockevent.cpumask = cpumask_of(boot_cpu_data.cpu_index);
clockevents_config_and_register(&hpet_clockevent, hpet_freq,
HPET_MIN_PROG_DELTA, 0x7FFFFFFF);
global_clock_event = &hpet_clockevent;
printk(KERN_DEBUG "hpet clockevent registered\n");
}
static int hpet_set_periodic(struct clock_event_device *evt, int timer)
{
unsigned int cfg, cmp, now;
uint64_t delta;
hpet_stop_counter();
delta = ((uint64_t)(NSEC_PER_SEC / HZ)) * evt->mult;
delta >>= evt->shift;
now = hpet_readl(HPET_COUNTER);
cmp = now + (unsigned int)delta;
cfg = hpet_readl(HPET_Tn_CFG(timer));
cfg |= HPET_TN_ENABLE | HPET_TN_PERIODIC | HPET_TN_SETVAL |
HPET_TN_32BIT;
hpet_writel(cfg, HPET_Tn_CFG(timer));
hpet_writel(cmp, HPET_Tn_CMP(timer));
udelay(1);
/*
* HPET on AMD 81xx needs a second write (with HPET_TN_SETVAL
* cleared) to T0_CMP to set the period. The HPET_TN_SETVAL
* bit is automatically cleared after the first write.
* (See AMD-8111 HyperTransport I/O Hub Data Sheet,
* Publication # 24674)
*/
hpet_writel((unsigned int)delta, HPET_Tn_CMP(timer));
hpet_start_counter();
hpet_print_config();
return 0;
}
static int hpet_set_oneshot(struct clock_event_device *evt, int timer)
{
unsigned int cfg;
cfg = hpet_readl(HPET_Tn_CFG(timer));
cfg &= ~HPET_TN_PERIODIC;
cfg |= HPET_TN_ENABLE | HPET_TN_32BIT;
hpet_writel(cfg, HPET_Tn_CFG(timer));
return 0;
}
static int hpet_shutdown(struct clock_event_device *evt, int timer)
{
unsigned int cfg;
cfg = hpet_readl(HPET_Tn_CFG(timer));
cfg &= ~HPET_TN_ENABLE;
hpet_writel(cfg, HPET_Tn_CFG(timer));
return 0;
}
static int hpet_resume(struct clock_event_device *evt)
{
hpet_enable_legacy_int();
hpet_print_config();
return 0;
}
static int hpet_next_event(unsigned long delta,
struct clock_event_device *evt, int timer)
{
u32 cnt;
s32 res;
cnt = hpet_readl(HPET_COUNTER);
cnt += (u32) delta;
hpet_writel(cnt, HPET_Tn_CMP(timer));
/*
* HPETs are a complete disaster. The compare register is
* based on a equal comparison and neither provides a less
* than or equal functionality (which would require to take
* the wraparound into account) nor a simple count down event
* mode. Further the write to the comparator register is
* delayed internally up to two HPET clock cycles in certain
* chipsets (ATI, ICH9,10). Some newer AMD chipsets have even
* longer delays. We worked around that by reading back the
* compare register, but that required another workaround for
* ICH9,10 chips where the first readout after write can
* return the old stale value. We already had a minimum
* programming delta of 5us enforced, but a NMI or SMI hitting
* between the counter readout and the comparator write can
* move us behind that point easily. Now instead of reading
* the compare register back several times, we make the ETIME
* decision based on the following: Return ETIME if the
* counter value after the write is less than HPET_MIN_CYCLES
* away from the event or if the counter is already ahead of
* the event. The minimum programming delta for the generic
* clockevents code is set to 1.5 * HPET_MIN_CYCLES.
*/
res = (s32)(cnt - hpet_readl(HPET_COUNTER));
return res < HPET_MIN_CYCLES ? -ETIME : 0;
}
static int hpet_legacy_shutdown(struct clock_event_device *evt)
{
return hpet_shutdown(evt, 0);
}
static int hpet_legacy_set_oneshot(struct clock_event_device *evt)
{
return hpet_set_oneshot(evt, 0);
}
static int hpet_legacy_set_periodic(struct clock_event_device *evt)
{
return hpet_set_periodic(evt, 0);
}
static int hpet_legacy_resume(struct clock_event_device *evt)
{
return hpet_resume(evt);
}
static int hpet_legacy_next_event(unsigned long delta,
struct clock_event_device *evt)
{
return hpet_next_event(delta, evt, 0);
}
/*
* The hpet clock event device
*/
static struct clock_event_device hpet_clockevent = {
.name = "hpet",
.features = CLOCK_EVT_FEAT_PERIODIC |
CLOCK_EVT_FEAT_ONESHOT,
.set_state_periodic = hpet_legacy_set_periodic,
.set_state_oneshot = hpet_legacy_set_oneshot,
.set_state_shutdown = hpet_legacy_shutdown,
.tick_resume = hpet_legacy_resume,
.set_next_event = hpet_legacy_next_event,
.irq = 0,
.rating = 50,
};
/*
* HPET MSI Support
*/
#ifdef CONFIG_PCI_MSI
static DEFINE_PER_CPU(struct hpet_dev *, cpu_hpet_dev);
static struct hpet_dev *hpet_devs;
static struct irq_domain *hpet_domain;
void hpet_msi_unmask(struct irq_data *data)
{
struct hpet_dev *hdev = irq_data_get_irq_handler_data(data);
unsigned int cfg;
/* unmask it */
cfg = hpet_readl(HPET_Tn_CFG(hdev->num));
cfg |= HPET_TN_ENABLE | HPET_TN_FSB;
hpet_writel(cfg, HPET_Tn_CFG(hdev->num));
}
void hpet_msi_mask(struct irq_data *data)
{
struct hpet_dev *hdev = irq_data_get_irq_handler_data(data);
unsigned int cfg;
/* mask it */
cfg = hpet_readl(HPET_Tn_CFG(hdev->num));
cfg &= ~(HPET_TN_ENABLE | HPET_TN_FSB);
hpet_writel(cfg, HPET_Tn_CFG(hdev->num));
}
void hpet_msi_write(struct hpet_dev *hdev, struct msi_msg *msg)
{
hpet_writel(msg->data, HPET_Tn_ROUTE(hdev->num));
hpet_writel(msg->address_lo, HPET_Tn_ROUTE(hdev->num) + 4);
}
void hpet_msi_read(struct hpet_dev *hdev, struct msi_msg *msg)
{
msg->data = hpet_readl(HPET_Tn_ROUTE(hdev->num));
msg->address_lo = hpet_readl(HPET_Tn_ROUTE(hdev->num) + 4);
msg->address_hi = 0;
}
static int hpet_msi_shutdown(struct clock_event_device *evt)
{
struct hpet_dev *hdev = EVT_TO_HPET_DEV(evt);
return hpet_shutdown(evt, hdev->num);
}
static int hpet_msi_set_oneshot(struct clock_event_device *evt)
{
struct hpet_dev *hdev = EVT_TO_HPET_DEV(evt);
return hpet_set_oneshot(evt, hdev->num);
}
static int hpet_msi_set_periodic(struct clock_event_device *evt)
{
struct hpet_dev *hdev = EVT_TO_HPET_DEV(evt);
return hpet_set_periodic(evt, hdev->num);
}
static int hpet_msi_resume(struct clock_event_device *evt)
{
struct hpet_dev *hdev = EVT_TO_HPET_DEV(evt);
struct irq_data *data = irq_get_irq_data(hdev->irq);
struct msi_msg msg;
/* Restore the MSI msg and unmask the interrupt */
irq_chip_compose_msi_msg(data, &msg);
hpet_msi_write(hdev, &msg);
hpet_msi_unmask(data);
return 0;
}
static int hpet_msi_next_event(unsigned long delta,
struct clock_event_device *evt)
{
struct hpet_dev *hdev = EVT_TO_HPET_DEV(evt);
return hpet_next_event(delta, evt, hdev->num);
}
static irqreturn_t hpet_interrupt_handler(int irq, void *data)
{
struct hpet_dev *dev = (struct hpet_dev *)data;
struct clock_event_device *hevt = &dev->evt;
if (!hevt->event_handler) {
printk(KERN_INFO "Spurious HPET timer interrupt on HPET timer %d\n",
dev->num);
return IRQ_HANDLED;
}
hevt->event_handler(hevt);
return IRQ_HANDLED;
}
static int hpet_setup_irq(struct hpet_dev *dev)
{
if (request_irq(dev->irq, hpet_interrupt_handler,
IRQF_TIMER | IRQF_NOBALANCING,
dev->name, dev))
return -1;
disable_irq(dev->irq);
irq_set_affinity(dev->irq, cpumask_of(dev->cpu));
enable_irq(dev->irq);
printk(KERN_DEBUG "hpet: %s irq %d for MSI\n",
dev->name, dev->irq);
return 0;
}
/* This should be called in specific @cpu */
static void init_one_hpet_msi_clockevent(struct hpet_dev *hdev, int cpu)
{
struct clock_event_device *evt = &hdev->evt;
WARN_ON(cpu != smp_processor_id());
if (!(hdev->flags & HPET_DEV_VALID))
return;
hdev->cpu = cpu;
per_cpu(cpu_hpet_dev, cpu) = hdev;
evt->name = hdev->name;
hpet_setup_irq(hdev);
evt->irq = hdev->irq;
evt->rating = 110;
evt->features = CLOCK_EVT_FEAT_ONESHOT;
if (hdev->flags & HPET_DEV_PERI_CAP) {
evt->features |= CLOCK_EVT_FEAT_PERIODIC;
evt->set_state_periodic = hpet_msi_set_periodic;
}
evt->set_state_shutdown = hpet_msi_shutdown;
evt->set_state_oneshot = hpet_msi_set_oneshot;
evt->tick_resume = hpet_msi_resume;
evt->set_next_event = hpet_msi_next_event;
evt->cpumask = cpumask_of(hdev->cpu);
clockevents_config_and_register(evt, hpet_freq, HPET_MIN_PROG_DELTA,
0x7FFFFFFF);
}
#ifdef CONFIG_HPET
/* Reserve at least one timer for userspace (/dev/hpet) */
#define RESERVE_TIMERS 1
#else
#define RESERVE_TIMERS 0
#endif
static void hpet_msi_capability_lookup(unsigned int start_timer)
{
unsigned int id;
unsigned int num_timers;
unsigned int num_timers_used = 0;
int i, irq;
if (hpet_msi_disable)
return;
if (boot_cpu_has(X86_FEATURE_ARAT))
return;
id = hpet_readl(HPET_ID);
num_timers = ((id & HPET_ID_NUMBER) >> HPET_ID_NUMBER_SHIFT);
num_timers++; /* Value read out starts from 0 */
hpet_print_config();
hpet_domain = hpet_create_irq_domain(hpet_blockid);
if (!hpet_domain)
return;
hpet_devs = kzalloc(sizeof(struct hpet_dev) * num_timers, GFP_KERNEL);
if (!hpet_devs)
return;
hpet_num_timers = num_timers;
for (i = start_timer; i < num_timers - RESERVE_TIMERS; i++) {
struct hpet_dev *hdev = &hpet_devs[num_timers_used];
unsigned int cfg = hpet_readl(HPET_Tn_CFG(i));
/* Only consider HPET timer with MSI support */
if (!(cfg & HPET_TN_FSB_CAP))
continue;
hdev->flags = 0;
if (cfg & HPET_TN_PERIODIC_CAP)
hdev->flags |= HPET_DEV_PERI_CAP;
sprintf(hdev->name, "hpet%d", i);
hdev->num = i;
irq = hpet_assign_irq(hpet_domain, hdev, hdev->num);
if (irq <= 0)
continue;
hdev->irq = irq;
hdev->flags |= HPET_DEV_FSB_CAP;
hdev->flags |= HPET_DEV_VALID;
num_timers_used++;
if (num_timers_used == num_possible_cpus())
break;
}
printk(KERN_INFO "HPET: %d timers in total, %d timers will be used for per-cpu timer\n",
num_timers, num_timers_used);
}
#ifdef CONFIG_HPET
static void hpet_reserve_msi_timers(struct hpet_data *hd)
{
int i;
if (!hpet_devs)
return;
for (i = 0; i < hpet_num_timers; i++) {
struct hpet_dev *hdev = &hpet_devs[i];
if (!(hdev->flags & HPET_DEV_VALID))
continue;
hd->hd_irq[hdev->num] = hdev->irq;
hpet_reserve_timer(hd, hdev->num);
}
}
#endif
static struct hpet_dev *hpet_get_unused_timer(void)
{
int i;
if (!hpet_devs)
return NULL;
for (i = 0; i < hpet_num_timers; i++) {
struct hpet_dev *hdev = &hpet_devs[i];
if (!(hdev->flags & HPET_DEV_VALID))
continue;
if (test_and_set_bit(HPET_DEV_USED_BIT,
(unsigned long *)&hdev->flags))
continue;
return hdev;
}
return NULL;
}
struct hpet_work_struct {
struct delayed_work work;
struct completion complete;
};
static void hpet_work(struct work_struct *w)
{
struct hpet_dev *hdev;
int cpu = smp_processor_id();
struct hpet_work_struct *hpet_work;
hpet_work = container_of(w, struct hpet_work_struct, work.work);
hdev = hpet_get_unused_timer();
if (hdev)
init_one_hpet_msi_clockevent(hdev, cpu);
complete(&hpet_work->complete);
}
static int hpet_cpuhp_online(unsigned int cpu)
{
struct hpet_work_struct work;
INIT_DELAYED_WORK_ONSTACK(&work.work, hpet_work);
init_completion(&work.complete);
/* FIXME: add schedule_work_on() */
schedule_delayed_work_on(cpu, &work.work, 0);
wait_for_completion(&work.complete);
destroy_delayed_work_on_stack(&work.work);
return 0;
}
static int hpet_cpuhp_dead(unsigned int cpu)
{
struct hpet_dev *hdev = per_cpu(cpu_hpet_dev, cpu);
if (!hdev)
return 0;
free_irq(hdev->irq, hdev);
hdev->flags &= ~HPET_DEV_USED;
per_cpu(cpu_hpet_dev, cpu) = NULL;
return 0;
}
#else
static void hpet_msi_capability_lookup(unsigned int start_timer)
{
return;
}
#ifdef CONFIG_HPET
static void hpet_reserve_msi_timers(struct hpet_data *hd)
{
return;
}
#endif
#define hpet_cpuhp_online NULL
#define hpet_cpuhp_dead NULL
#endif
/*
* Clock source related code
*/
#if defined(CONFIG_SMP) && defined(CONFIG_64BIT)
/*
* Reading the HPET counter is a very slow operation. If a large number of
* CPUs are trying to access the HPET counter simultaneously, it can cause
* massive delay and slow down system performance dramatically. This may
* happen when HPET is the default clock source instead of TSC. For a
* really large system with hundreds of CPUs, the slowdown may be so
* severe that it may actually crash the system because of a NMI watchdog
* soft lockup, for example.
*
* If multiple CPUs are trying to access the HPET counter at the same time,
* we don't actually need to read the counter multiple times. Instead, the
* other CPUs can use the counter value read by the first CPU in the group.
*
* This special feature is only enabled on x86-64 systems. It is unlikely
* that 32-bit x86 systems will have enough CPUs to require this feature
* with its associated locking overhead. And we also need 64-bit atomic
* read.
*
* The lock and the hpet value are stored together and can be read in a
* single atomic 64-bit read. It is explicitly assumed that arch_spinlock_t
* is 32 bits in size.
*/
union hpet_lock {
struct {
arch_spinlock_t lock;
u32 value;
};
u64 lockval;
};
static union hpet_lock hpet __cacheline_aligned = {
{ .lock = __ARCH_SPIN_LOCK_UNLOCKED, },
};
static u64 read_hpet(struct clocksource *cs)
{
unsigned long flags;
union hpet_lock old, new;
BUILD_BUG_ON(sizeof(union hpet_lock) != 8);
/*
* Read HPET directly if in NMI.
*/
if (in_nmi())
return (u64)hpet_readl(HPET_COUNTER);
/*
* Read the current state of the lock and HPET value atomically.
*/
old.lockval = READ_ONCE(hpet.lockval);
if (arch_spin_is_locked(&old.lock))
goto contended;
local_irq_save(flags);
if (arch_spin_trylock(&hpet.lock)) {
new.value = hpet_readl(HPET_COUNTER);
/*
* Use WRITE_ONCE() to prevent store tearing.
*/
WRITE_ONCE(hpet.value, new.value);
arch_spin_unlock(&hpet.lock);
local_irq_restore(flags);
return (u64)new.value;
}
local_irq_restore(flags);
contended:
/*
* Contended case
* --------------
* Wait until the HPET value change or the lock is free to indicate
* its value is up-to-date.
*
* It is possible that old.value has already contained the latest
* HPET value while the lock holder was in the process of releasing
* the lock. Checking for lock state change will enable us to return
* the value immediately instead of waiting for the next HPET reader
* to come along.
*/
do {
cpu_relax();
new.lockval = READ_ONCE(hpet.lockval);
} while ((new.value == old.value) && arch_spin_is_locked(&new.lock));
return (u64)new.value;
}
#else
/*
* For UP or 32-bit.
*/
static u64 read_hpet(struct clocksource *cs)
{
return (u64)hpet_readl(HPET_COUNTER);
}
#endif
static struct clocksource clocksource_hpet = {
.name = "hpet",
.rating = 250,
.read = read_hpet,
.mask = HPET_MASK,
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
.resume = hpet_resume_counter,
};
static int hpet_clocksource_register(void)
{
u64 start, now;
u64 t1;
/* Start the counter */
hpet_restart_counter();
/* Verify whether hpet counter works */
t1 = hpet_readl(HPET_COUNTER);
start = rdtsc();
/*
* 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();
now = rdtsc();
} while ((now - start) < 200000UL);
if (t1 == hpet_readl(HPET_COUNTER)) {
printk(KERN_WARNING
"HPET counter not counting. HPET disabled\n");
return -ENODEV;
}
clocksource_register_hz(&clocksource_hpet, (u32)hpet_freq);
return 0;
}
static u32 *hpet_boot_cfg;
/**
* hpet_enable - Try to setup the HPET timer. Returns 1 on success.
*/
int __init hpet_enable(void)
{
u32 hpet_period, cfg, id;
u64 freq;
unsigned int i, last;
if (!is_hpet_capable())
return 0;
hpet_set_mapping();
/*
* Read the period and check for a sane value:
*/
hpet_period = hpet_readl(HPET_PERIOD);
/*
* AMD SB700 based systems with spread spectrum enabled use a
* SMM based HPET emulation to provide proper frequency
* setting. The SMM code is initialized with the first HPET
* register access and takes some time to complete. During
* this time the config register reads 0xffffffff. We check
* for max. 1000 loops whether the config register reads a non
* 0xffffffff value to make sure that HPET is up and running
* before we go further. A counting loop is safe, as the HPET
* access takes thousands of CPU cycles. On non SB700 based
* machines this check is only done once and has no side
* effects.
*/
for (i = 0; hpet_readl(HPET_CFG) == 0xFFFFFFFF; i++) {
if (i == 1000) {
printk(KERN_WARNING
"HPET config register value = 0xFFFFFFFF. "
"Disabling HPET\n");
goto out_nohpet;
}
}
if (hpet_period < HPET_MIN_PERIOD || hpet_period > HPET_MAX_PERIOD)
goto out_nohpet;
/*
* The period is a femto seconds value. Convert it to a
* frequency.
*/
freq = FSEC_PER_SEC;
do_div(freq, hpet_period);
hpet_freq = freq;
/*
* Read the HPET ID register to retrieve the IRQ routing
* information and the number of channels
*/
id = hpet_readl(HPET_ID);
hpet_print_config();
last = (id & HPET_ID_NUMBER) >> HPET_ID_NUMBER_SHIFT;
#ifdef CONFIG_HPET_EMULATE_RTC
/*
* The legacy routing mode needs at least two channels, tick timer
* and the rtc emulation channel.
*/
if (!last)
goto out_nohpet;
#endif
cfg = hpet_readl(HPET_CFG);
hpet_boot_cfg = kmalloc((last + 2) * sizeof(*hpet_boot_cfg),
GFP_KERNEL);
if (hpet_boot_cfg)
*hpet_boot_cfg = cfg;
else
pr_warn("HPET initial state will not be saved\n");
cfg &= ~(HPET_CFG_ENABLE | HPET_CFG_LEGACY);
hpet_writel(cfg, HPET_CFG);
if (cfg)
pr_warn("HPET: Unrecognized bits %#x set in global cfg\n",
cfg);
for (i = 0; i <= last; ++i) {
cfg = hpet_readl(HPET_Tn_CFG(i));
if (hpet_boot_cfg)
hpet_boot_cfg[i + 1] = cfg;
cfg &= ~(HPET_TN_ENABLE | HPET_TN_LEVEL | HPET_TN_FSB);
hpet_writel(cfg, HPET_Tn_CFG(i));
cfg &= ~(HPET_TN_PERIODIC | HPET_TN_PERIODIC_CAP
| HPET_TN_64BIT_CAP | HPET_TN_32BIT | HPET_TN_ROUTE
| HPET_TN_FSB | HPET_TN_FSB_CAP);
if (cfg)
pr_warn("HPET: Unrecognized bits %#x set in cfg#%u\n",
cfg, i);
}
hpet_print_config();
if (hpet_clocksource_register())
goto out_nohpet;
if (id & HPET_ID_LEGSUP) {
hpet_legacy_clockevent_register();
return 1;
}
return 0;
out_nohpet:
hpet_clear_mapping();
hpet_address = 0;
return 0;
}
/*
* Needs to be late, as the reserve_timer code calls kalloc !
*
* Not a problem on i386 as hpet_enable is called from late_time_init,
* but on x86_64 it is necessary !
*/
static __init int hpet_late_init(void)
{
int ret;
if (boot_hpet_disable)
return -ENODEV;
if (!hpet_address) {
if (!force_hpet_address)
return -ENODEV;
hpet_address = force_hpet_address;
hpet_enable();
}
if (!hpet_virt_address)
return -ENODEV;
if (hpet_readl(HPET_ID) & HPET_ID_LEGSUP)
hpet_msi_capability_lookup(2);
else
hpet_msi_capability_lookup(0);
hpet_reserve_platform_timers(hpet_readl(HPET_ID));
hpet_print_config();
if (hpet_msi_disable)
return 0;
if (boot_cpu_has(X86_FEATURE_ARAT))
return 0;
/* This notifier should be called after workqueue is ready */
ret = cpuhp_setup_state(CPUHP_AP_X86_HPET_ONLINE, "x86/hpet:online",
hpet_cpuhp_online, NULL);
if (ret)
return ret;
ret = cpuhp_setup_state(CPUHP_X86_HPET_DEAD, "x86/hpet:dead", NULL,
hpet_cpuhp_dead);
if (ret)
goto err_cpuhp;
return 0;
err_cpuhp:
cpuhp_remove_state(CPUHP_AP_X86_HPET_ONLINE);
return ret;
}
fs_initcall(hpet_late_init);
void hpet_disable(void)
{
if (is_hpet_capable() && hpet_virt_address) {
unsigned int cfg = hpet_readl(HPET_CFG), id, last;
if (hpet_boot_cfg)
cfg = *hpet_boot_cfg;
else if (hpet_legacy_int_enabled) {
cfg &= ~HPET_CFG_LEGACY;
hpet_legacy_int_enabled = false;
}
cfg &= ~HPET_CFG_ENABLE;
hpet_writel(cfg, HPET_CFG);
if (!hpet_boot_cfg)
return;
id = hpet_readl(HPET_ID);
last = ((id & HPET_ID_NUMBER) >> HPET_ID_NUMBER_SHIFT);
for (id = 0; id <= last; ++id)
hpet_writel(hpet_boot_cfg[id + 1], HPET_Tn_CFG(id));
if (*hpet_boot_cfg & HPET_CFG_ENABLE)
hpet_writel(*hpet_boot_cfg, HPET_CFG);
}
}
#ifdef CONFIG_HPET_EMULATE_RTC
/* HPET in LegacyReplacement Mode eats up RTC interrupt line. When, HPET
* is enabled, we support RTC interrupt functionality in software.
* RTC has 3 kinds of interrupts:
* 1) Update Interrupt - generate an interrupt, every sec, when RTC clock
* is updated
* 2) Alarm Interrupt - generate an interrupt at a specific time of day
* 3) Periodic Interrupt - generate periodic interrupt, with frequencies
* 2Hz-8192Hz (2Hz-64Hz for non-root user) (all freqs in powers of 2)
* (1) and (2) above are implemented using polling at a frequency of
* 64 Hz. The exact frequency is a tradeoff between accuracy and interrupt
* overhead. (DEFAULT_RTC_INT_FREQ)
* For (3), we use interrupts at 64Hz or user specified periodic
* frequency, whichever is higher.
*/
#include <linux/mc146818rtc.h>
#include <linux/rtc.h>
#define DEFAULT_RTC_INT_FREQ 64
#define DEFAULT_RTC_SHIFT 6
#define RTC_NUM_INTS 1
static unsigned long hpet_rtc_flags;
static int hpet_prev_update_sec;
static struct rtc_time hpet_alarm_time;
static unsigned long hpet_pie_count;
static u32 hpet_t1_cmp;
static u32 hpet_default_delta;
static u32 hpet_pie_delta;
static unsigned long hpet_pie_limit;
static rtc_irq_handler irq_handler;
/*
* Check that the hpet counter c1 is ahead of the c2
*/
static inline int hpet_cnt_ahead(u32 c1, u32 c2)
{
return (s32)(c2 - c1) < 0;
}
/*
* Registers a IRQ handler.
*/
int hpet_register_irq_handler(rtc_irq_handler handler)
{
if (!is_hpet_enabled())
return -ENODEV;
if (irq_handler)
return -EBUSY;
irq_handler = handler;
return 0;
}
EXPORT_SYMBOL_GPL(hpet_register_irq_handler);
/*
* Deregisters the IRQ handler registered with hpet_register_irq_handler()
* and does cleanup.
*/
void hpet_unregister_irq_handler(rtc_irq_handler handler)
{
if (!is_hpet_enabled())
return;
irq_handler = NULL;
hpet_rtc_flags = 0;
}
EXPORT_SYMBOL_GPL(hpet_unregister_irq_handler);
/*
* Timer 1 for RTC emulation. We use one shot mode, as periodic mode
* is not supported by all HPET implementations for timer 1.
*
* hpet_rtc_timer_init() is called when the rtc is initialized.
*/
int hpet_rtc_timer_init(void)
{
unsigned int cfg, cnt, delta;
unsigned long flags;
if (!is_hpet_enabled())
return 0;
if (!hpet_default_delta) {
uint64_t clc;
clc = (uint64_t) hpet_clockevent.mult * NSEC_PER_SEC;
clc >>= hpet_clockevent.shift + DEFAULT_RTC_SHIFT;
hpet_default_delta = clc;
}
if (!(hpet_rtc_flags & RTC_PIE) || hpet_pie_limit)
delta = hpet_default_delta;
else
delta = hpet_pie_delta;
local_irq_save(flags);
cnt = delta + hpet_readl(HPET_COUNTER);
hpet_writel(cnt, HPET_T1_CMP);
hpet_t1_cmp = cnt;
cfg = hpet_readl(HPET_T1_CFG);
cfg &= ~HPET_TN_PERIODIC;
cfg |= HPET_TN_ENABLE | HPET_TN_32BIT;
hpet_writel(cfg, HPET_T1_CFG);
local_irq_restore(flags);
return 1;
}
EXPORT_SYMBOL_GPL(hpet_rtc_timer_init);
static void hpet_disable_rtc_channel(void)
{
u32 cfg = hpet_readl(HPET_T1_CFG);
cfg &= ~HPET_TN_ENABLE;
hpet_writel(cfg, HPET_T1_CFG);
}
/*
* The functions below are called from rtc driver.
* Return 0 if HPET is not being used.
* Otherwise do the necessary changes and return 1.
*/
int hpet_mask_rtc_irq_bit(unsigned long bit_mask)
{
if (!is_hpet_enabled())
return 0;
hpet_rtc_flags &= ~bit_mask;
if (unlikely(!hpet_rtc_flags))
hpet_disable_rtc_channel();
return 1;
}
EXPORT_SYMBOL_GPL(hpet_mask_rtc_irq_bit);
int hpet_set_rtc_irq_bit(unsigned long bit_mask)
{
unsigned long oldbits = hpet_rtc_flags;
if (!is_hpet_enabled())
return 0;
hpet_rtc_flags |= bit_mask;
if ((bit_mask & RTC_UIE) && !(oldbits & RTC_UIE))
hpet_prev_update_sec = -1;
if (!oldbits)
hpet_rtc_timer_init();
return 1;
}
EXPORT_SYMBOL_GPL(hpet_set_rtc_irq_bit);
int hpet_set_alarm_time(unsigned char hrs, unsigned char min,
unsigned char sec)
{
if (!is_hpet_enabled())
return 0;
hpet_alarm_time.tm_hour = hrs;
hpet_alarm_time.tm_min = min;
hpet_alarm_time.tm_sec = sec;
return 1;
}
EXPORT_SYMBOL_GPL(hpet_set_alarm_time);
int hpet_set_periodic_freq(unsigned long freq)
{
uint64_t clc;
if (!is_hpet_enabled())
return 0;
if (freq <= DEFAULT_RTC_INT_FREQ)
hpet_pie_limit = DEFAULT_RTC_INT_FREQ / freq;
else {
clc = (uint64_t) hpet_clockevent.mult * NSEC_PER_SEC;
do_div(clc, freq);
clc >>= hpet_clockevent.shift;
hpet_pie_delta = clc;
hpet_pie_limit = 0;
}
return 1;
}
EXPORT_SYMBOL_GPL(hpet_set_periodic_freq);
int hpet_rtc_dropped_irq(void)
{
return is_hpet_enabled();
}
EXPORT_SYMBOL_GPL(hpet_rtc_dropped_irq);
static void hpet_rtc_timer_reinit(void)
{
unsigned int delta;
int lost_ints = -1;
if (unlikely(!hpet_rtc_flags))
hpet_disable_rtc_channel();
if (!(hpet_rtc_flags & RTC_PIE) || hpet_pie_limit)
delta = hpet_default_delta;
else
delta = hpet_pie_delta;
/*
* Increment the comparator value until we are ahead of the
* current count.
*/
do {
hpet_t1_cmp += delta;
hpet_writel(hpet_t1_cmp, HPET_T1_CMP);
lost_ints++;
} while (!hpet_cnt_ahead(hpet_t1_cmp, hpet_readl(HPET_COUNTER)));
if (lost_ints) {
if (hpet_rtc_flags & RTC_PIE)
hpet_pie_count += lost_ints;
if (printk_ratelimit())
printk(KERN_WARNING "hpet1: lost %d rtc interrupts\n",
lost_ints);
}
}
irqreturn_t hpet_rtc_interrupt(int irq, void *dev_id)
{
struct rtc_time curr_time;
unsigned long rtc_int_flag = 0;
hpet_rtc_timer_reinit();
memset(&curr_time, 0, sizeof(struct rtc_time));
if (hpet_rtc_flags & (RTC_UIE | RTC_AIE))
mc146818_get_time(&curr_time);
if (hpet_rtc_flags & RTC_UIE &&
curr_time.tm_sec != hpet_prev_update_sec) {
if (hpet_prev_update_sec >= 0)
rtc_int_flag = RTC_UF;
hpet_prev_update_sec = curr_time.tm_sec;
}
if (hpet_rtc_flags & RTC_PIE &&
++hpet_pie_count >= hpet_pie_limit) {
rtc_int_flag |= RTC_PF;
hpet_pie_count = 0;
}
if (hpet_rtc_flags & RTC_AIE &&
(curr_time.tm_sec == hpet_alarm_time.tm_sec) &&
(curr_time.tm_min == hpet_alarm_time.tm_min) &&
(curr_time.tm_hour == hpet_alarm_time.tm_hour))
rtc_int_flag |= RTC_AF;
if (rtc_int_flag) {
rtc_int_flag |= (RTC_IRQF | (RTC_NUM_INTS << 8));
if (irq_handler)
irq_handler(rtc_int_flag, dev_id);
}
return IRQ_HANDLED;
}
EXPORT_SYMBOL_GPL(hpet_rtc_interrupt);
#endif