https://github.com/torvalds/linux
Tip revision: 4fe89d07dcc2804c8b562f6c7896a45643d34b2f authored by Linus Torvalds on 02 October 2022, 21:09:07 UTC
Linux 6.0
Linux 6.0
Tip revision: 4fe89d0
hpet.c
// SPDX-License-Identifier: GPL-2.0-only
#include <linux/clockchips.h>
#include <linux/interrupt.h>
#include <linux/export.h>
#include <linux/delay.h>
#include <linux/hpet.h>
#include <linux/cpu.h>
#include <linux/irq.h>
#include <asm/irq_remapping.h>
#include <asm/hpet.h>
#include <asm/time.h>
#include <asm/mwait.h>
#undef pr_fmt
#define pr_fmt(fmt) "hpet: " fmt
enum hpet_mode {
HPET_MODE_UNUSED,
HPET_MODE_LEGACY,
HPET_MODE_CLOCKEVT,
HPET_MODE_DEVICE,
};
struct hpet_channel {
struct clock_event_device evt;
unsigned int num;
unsigned int cpu;
unsigned int irq;
unsigned int in_use;
enum hpet_mode mode;
unsigned int boot_cfg;
char name[10];
};
struct hpet_base {
unsigned int nr_channels;
unsigned int nr_clockevents;
unsigned int boot_cfg;
struct hpet_channel *channels;
};
#define HPET_MASK CLOCKSOURCE_MASK(32)
#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_GENERIC_MSI_IRQ
static DEFINE_PER_CPU(struct hpet_channel *, cpu_hpet_channel);
static struct irq_domain *hpet_domain;
#endif
static void __iomem *hpet_virt_address;
static struct hpet_base hpet_base;
static bool hpet_legacy_int_enabled;
static unsigned long hpet_freq;
bool boot_hpet_disable;
bool hpet_force_user;
static bool hpet_verbose;
static inline
struct hpet_channel *clockevent_to_channel(struct clock_event_device *evt)
{
return container_of(evt, struct hpet_channel, 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);
}
static inline void hpet_set_mapping(void)
{
hpet_virt_address = ioremap(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
*/
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;
}
/**
* is_hpet_enabled - Check whether the legacy 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, id, period, cfg, status, channels, l, h;
pr_info("%s(%d):\n", function, line);
id = hpet_readl(HPET_ID);
period = hpet_readl(HPET_PERIOD);
pr_info("ID: 0x%x, PERIOD: 0x%x\n", id, period);
cfg = hpet_readl(HPET_CFG);
status = hpet_readl(HPET_STATUS);
pr_info("CFG: 0x%x, STATUS: 0x%x\n", cfg, status);
l = hpet_readl(HPET_COUNTER);
h = hpet_readl(HPET_COUNTER+4);
pr_info("COUNTER_l: 0x%x, COUNTER_h: 0x%x\n", l, h);
channels = ((id & HPET_ID_NUMBER) >> HPET_ID_NUMBER_SHIFT) + 1;
for (i = 0; i < channels; i++) {
l = hpet_readl(HPET_Tn_CFG(i));
h = hpet_readl(HPET_Tn_CFG(i)+4);
pr_info("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);
pr_info("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);
pr_info("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 __init hpet_reserve_platform_timers(void)
{
struct hpet_data hd;
unsigned int i;
memset(&hd, 0, sizeof(hd));
hd.hd_phys_address = hpet_address;
hd.hd_address = hpet_virt_address;
hd.hd_nirqs = hpet_base.nr_channels;
/*
* 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 = 0; i < hpet_base.nr_channels; i++) {
struct hpet_channel *hc = hpet_base.channels + i;
if (i >= 2)
hd.hd_irq[i] = hc->irq;
switch (hc->mode) {
case HPET_MODE_UNUSED:
case HPET_MODE_DEVICE:
hc->mode = HPET_MODE_DEVICE;
break;
case HPET_MODE_CLOCKEVT:
case HPET_MODE_LEGACY:
hpet_reserve_timer(&hd, hc->num);
break;
}
}
hpet_alloc(&hd);
}
static void __init hpet_select_device_channel(void)
{
int i;
for (i = 0; i < hpet_base.nr_channels; i++) {
struct hpet_channel *hc = hpet_base.channels + i;
/* Associate the first unused channel to /dev/hpet */
if (hc->mode == HPET_MODE_UNUSED) {
hc->mode = HPET_MODE_DEVICE;
return;
}
}
}
#else
static inline void hpet_reserve_platform_timers(void) { }
static inline void hpet_select_device_channel(void) {}
#endif
/* Common HPET functions */
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 int hpet_clkevt_set_state_periodic(struct clock_event_device *evt)
{
unsigned int channel = clockevent_to_channel(evt)->num;
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(channel));
cfg |= HPET_TN_ENABLE | HPET_TN_PERIODIC | HPET_TN_SETVAL |
HPET_TN_32BIT;
hpet_writel(cfg, HPET_Tn_CFG(channel));
hpet_writel(cmp, HPET_Tn_CMP(channel));
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(channel));
hpet_start_counter();
hpet_print_config();
return 0;
}
static int hpet_clkevt_set_state_oneshot(struct clock_event_device *evt)
{
unsigned int channel = clockevent_to_channel(evt)->num;
unsigned int cfg;
cfg = hpet_readl(HPET_Tn_CFG(channel));
cfg &= ~HPET_TN_PERIODIC;
cfg |= HPET_TN_ENABLE | HPET_TN_32BIT;
hpet_writel(cfg, HPET_Tn_CFG(channel));
return 0;
}
static int hpet_clkevt_set_state_shutdown(struct clock_event_device *evt)
{
unsigned int channel = clockevent_to_channel(evt)->num;
unsigned int cfg;
cfg = hpet_readl(HPET_Tn_CFG(channel));
cfg &= ~HPET_TN_ENABLE;
hpet_writel(cfg, HPET_Tn_CFG(channel));
return 0;
}
static int hpet_clkevt_legacy_resume(struct clock_event_device *evt)
{
hpet_enable_legacy_int();
hpet_print_config();
return 0;
}
static int
hpet_clkevt_set_next_event(unsigned long delta, struct clock_event_device *evt)
{
unsigned int channel = clockevent_to_channel(evt)->num;
u32 cnt;
s32 res;
cnt = hpet_readl(HPET_COUNTER);
cnt += (u32) delta;
hpet_writel(cnt, HPET_Tn_CMP(channel));
/*
* 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 void hpet_init_clockevent(struct hpet_channel *hc, unsigned int rating)
{
struct clock_event_device *evt = &hc->evt;
evt->rating = rating;
evt->irq = hc->irq;
evt->name = hc->name;
evt->cpumask = cpumask_of(hc->cpu);
evt->set_state_oneshot = hpet_clkevt_set_state_oneshot;
evt->set_next_event = hpet_clkevt_set_next_event;
evt->set_state_shutdown = hpet_clkevt_set_state_shutdown;
evt->features = CLOCK_EVT_FEAT_ONESHOT;
if (hc->boot_cfg & HPET_TN_PERIODIC) {
evt->features |= CLOCK_EVT_FEAT_PERIODIC;
evt->set_state_periodic = hpet_clkevt_set_state_periodic;
}
}
static void __init hpet_legacy_clockevent_register(struct hpet_channel *hc)
{
/*
* Start HPET with the boot CPU's cpumask and make it global after
* the IO_APIC has been initialized.
*/
hc->cpu = boot_cpu_data.cpu_index;
strncpy(hc->name, "hpet", sizeof(hc->name));
hpet_init_clockevent(hc, 50);
hc->evt.tick_resume = hpet_clkevt_legacy_resume;
/*
* Legacy horrors and sins from the past. HPET used periodic mode
* unconditionally forever on the legacy channel 0. Removing the
* below hack and using the conditional in hpet_init_clockevent()
* makes at least Qemu and one hardware machine fail to boot.
* There are two issues which cause the boot failure:
*
* #1 After the timer delivery test in IOAPIC and the IOAPIC setup
* the next interrupt is not delivered despite the HPET channel
* being programmed correctly. Reprogramming the HPET after
* switching to IOAPIC makes it work again. After fixing this,
* the next issue surfaces:
*
* #2 Due to the unconditional periodic mode availability the Local
* APIC timer calibration can hijack the global clockevents
* event handler without causing damage. Using oneshot at this
* stage makes if hang because the HPET does not get
* reprogrammed due to the handler hijacking. Duh, stupid me!
*
* Both issues require major surgery and especially the kick HPET
* again after enabling IOAPIC results in really nasty hackery.
* This 'assume periodic works' magic has survived since HPET
* support got added, so it's questionable whether this should be
* fixed. Both Qemu and the failing hardware machine support
* periodic mode despite the fact that both don't advertise it in
* the configuration register and both need that extra kick after
* switching to IOAPIC. Seems to be a feature...
*/
hc->evt.features |= CLOCK_EVT_FEAT_PERIODIC;
hc->evt.set_state_periodic = hpet_clkevt_set_state_periodic;
/* Start HPET legacy interrupts */
hpet_enable_legacy_int();
clockevents_config_and_register(&hc->evt, hpet_freq,
HPET_MIN_PROG_DELTA, 0x7FFFFFFF);
global_clock_event = &hc->evt;
pr_debug("Clockevent registered\n");
}
/*
* HPET MSI Support
*/
#ifdef CONFIG_GENERIC_MSI_IRQ
static void hpet_msi_unmask(struct irq_data *data)
{
struct hpet_channel *hc = irq_data_get_irq_handler_data(data);
unsigned int cfg;
cfg = hpet_readl(HPET_Tn_CFG(hc->num));
cfg |= HPET_TN_ENABLE | HPET_TN_FSB;
hpet_writel(cfg, HPET_Tn_CFG(hc->num));
}
static void hpet_msi_mask(struct irq_data *data)
{
struct hpet_channel *hc = irq_data_get_irq_handler_data(data);
unsigned int cfg;
cfg = hpet_readl(HPET_Tn_CFG(hc->num));
cfg &= ~(HPET_TN_ENABLE | HPET_TN_FSB);
hpet_writel(cfg, HPET_Tn_CFG(hc->num));
}
static void hpet_msi_write(struct hpet_channel *hc, struct msi_msg *msg)
{
hpet_writel(msg->data, HPET_Tn_ROUTE(hc->num));
hpet_writel(msg->address_lo, HPET_Tn_ROUTE(hc->num) + 4);
}
static void hpet_msi_write_msg(struct irq_data *data, struct msi_msg *msg)
{
hpet_msi_write(irq_data_get_irq_handler_data(data), msg);
}
static struct irq_chip hpet_msi_controller __ro_after_init = {
.name = "HPET-MSI",
.irq_unmask = hpet_msi_unmask,
.irq_mask = hpet_msi_mask,
.irq_ack = irq_chip_ack_parent,
.irq_set_affinity = msi_domain_set_affinity,
.irq_retrigger = irq_chip_retrigger_hierarchy,
.irq_write_msi_msg = hpet_msi_write_msg,
.flags = IRQCHIP_SKIP_SET_WAKE | IRQCHIP_AFFINITY_PRE_STARTUP,
};
static int hpet_msi_init(struct irq_domain *domain,
struct msi_domain_info *info, unsigned int virq,
irq_hw_number_t hwirq, msi_alloc_info_t *arg)
{
irq_set_status_flags(virq, IRQ_MOVE_PCNTXT);
irq_domain_set_info(domain, virq, arg->hwirq, info->chip, NULL,
handle_edge_irq, arg->data, "edge");
return 0;
}
static void hpet_msi_free(struct irq_domain *domain,
struct msi_domain_info *info, unsigned int virq)
{
irq_clear_status_flags(virq, IRQ_MOVE_PCNTXT);
}
static struct msi_domain_ops hpet_msi_domain_ops = {
.msi_init = hpet_msi_init,
.msi_free = hpet_msi_free,
};
static struct msi_domain_info hpet_msi_domain_info = {
.ops = &hpet_msi_domain_ops,
.chip = &hpet_msi_controller,
.flags = MSI_FLAG_USE_DEF_DOM_OPS,
};
static struct irq_domain *hpet_create_irq_domain(int hpet_id)
{
struct msi_domain_info *domain_info;
struct irq_domain *parent, *d;
struct fwnode_handle *fn;
struct irq_fwspec fwspec;
if (x86_vector_domain == NULL)
return NULL;
domain_info = kzalloc(sizeof(*domain_info), GFP_KERNEL);
if (!domain_info)
return NULL;
*domain_info = hpet_msi_domain_info;
domain_info->data = (void *)(long)hpet_id;
fn = irq_domain_alloc_named_id_fwnode(hpet_msi_controller.name,
hpet_id);
if (!fn) {
kfree(domain_info);
return NULL;
}
fwspec.fwnode = fn;
fwspec.param_count = 1;
fwspec.param[0] = hpet_id;
parent = irq_find_matching_fwspec(&fwspec, DOMAIN_BUS_ANY);
if (!parent) {
irq_domain_free_fwnode(fn);
kfree(domain_info);
return NULL;
}
if (parent != x86_vector_domain)
hpet_msi_controller.name = "IR-HPET-MSI";
d = msi_create_irq_domain(fn, domain_info, parent);
if (!d) {
irq_domain_free_fwnode(fn);
kfree(domain_info);
}
return d;
}
static inline int hpet_dev_id(struct irq_domain *domain)
{
struct msi_domain_info *info = msi_get_domain_info(domain);
return (int)(long)info->data;
}
static int hpet_assign_irq(struct irq_domain *domain, struct hpet_channel *hc,
int dev_num)
{
struct irq_alloc_info info;
init_irq_alloc_info(&info, NULL);
info.type = X86_IRQ_ALLOC_TYPE_HPET;
info.data = hc;
info.devid = hpet_dev_id(domain);
info.hwirq = dev_num;
return irq_domain_alloc_irqs(domain, 1, NUMA_NO_NODE, &info);
}
static int hpet_clkevt_msi_resume(struct clock_event_device *evt)
{
struct hpet_channel *hc = clockevent_to_channel(evt);
struct irq_data *data = irq_get_irq_data(hc->irq);
struct msi_msg msg;
/* Restore the MSI msg and unmask the interrupt */
irq_chip_compose_msi_msg(data, &msg);
hpet_msi_write(hc, &msg);
hpet_msi_unmask(data);
return 0;
}
static irqreturn_t hpet_msi_interrupt_handler(int irq, void *data)
{
struct hpet_channel *hc = data;
struct clock_event_device *evt = &hc->evt;
if (!evt->event_handler) {
pr_info("Spurious interrupt HPET channel %d\n", hc->num);
return IRQ_HANDLED;
}
evt->event_handler(evt);
return IRQ_HANDLED;
}
static int hpet_setup_msi_irq(struct hpet_channel *hc)
{
if (request_irq(hc->irq, hpet_msi_interrupt_handler,
IRQF_TIMER | IRQF_NOBALANCING,
hc->name, hc))
return -1;
disable_irq(hc->irq);
irq_set_affinity(hc->irq, cpumask_of(hc->cpu));
enable_irq(hc->irq);
pr_debug("%s irq %u for MSI\n", hc->name, hc->irq);
return 0;
}
/* Invoked from the hotplug callback on @cpu */
static void init_one_hpet_msi_clockevent(struct hpet_channel *hc, int cpu)
{
struct clock_event_device *evt = &hc->evt;
hc->cpu = cpu;
per_cpu(cpu_hpet_channel, cpu) = hc;
hpet_setup_msi_irq(hc);
hpet_init_clockevent(hc, 110);
evt->tick_resume = hpet_clkevt_msi_resume;
clockevents_config_and_register(evt, hpet_freq, HPET_MIN_PROG_DELTA,
0x7FFFFFFF);
}
static struct hpet_channel *hpet_get_unused_clockevent(void)
{
int i;
for (i = 0; i < hpet_base.nr_channels; i++) {
struct hpet_channel *hc = hpet_base.channels + i;
if (hc->mode != HPET_MODE_CLOCKEVT || hc->in_use)
continue;
hc->in_use = 1;
return hc;
}
return NULL;
}
static int hpet_cpuhp_online(unsigned int cpu)
{
struct hpet_channel *hc = hpet_get_unused_clockevent();
if (hc)
init_one_hpet_msi_clockevent(hc, cpu);
return 0;
}
static int hpet_cpuhp_dead(unsigned int cpu)
{
struct hpet_channel *hc = per_cpu(cpu_hpet_channel, cpu);
if (!hc)
return 0;
free_irq(hc->irq, hc);
hc->in_use = 0;
per_cpu(cpu_hpet_channel, cpu) = NULL;
return 0;
}
static void __init hpet_select_clockevents(void)
{
unsigned int i;
hpet_base.nr_clockevents = 0;
/* No point if MSI is disabled or CPU has an Always Runing APIC Timer */
if (hpet_msi_disable || boot_cpu_has(X86_FEATURE_ARAT))
return;
hpet_print_config();
hpet_domain = hpet_create_irq_domain(hpet_blockid);
if (!hpet_domain)
return;
for (i = 0; i < hpet_base.nr_channels; i++) {
struct hpet_channel *hc = hpet_base.channels + i;
int irq;
if (hc->mode != HPET_MODE_UNUSED)
continue;
/* Only consider HPET channel with MSI support */
if (!(hc->boot_cfg & HPET_TN_FSB_CAP))
continue;
sprintf(hc->name, "hpet%d", i);
irq = hpet_assign_irq(hpet_domain, hc, hc->num);
if (irq <= 0)
continue;
hc->irq = irq;
hc->mode = HPET_MODE_CLOCKEVT;
if (++hpet_base.nr_clockevents == num_possible_cpus())
break;
}
pr_info("%d channels of %d reserved for per-cpu timers\n",
hpet_base.nr_channels, hpet_base.nr_clockevents);
}
#else
static inline void hpet_select_clockevents(void) { }
#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 delays 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 can 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. 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,
};
/*
* AMD SB700 based systems with spread spectrum enabled use a SMM based
* HPET emulation to provide proper frequency setting.
*
* On such systems 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 the
* HPET is up and running before we proceed any 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.
*/
static bool __init hpet_cfg_working(void)
{
int i;
for (i = 0; i < 1000; i++) {
if (hpet_readl(HPET_CFG) != 0xFFFFFFFF)
return true;
}
pr_warn("Config register invalid. Disabling HPET\n");
return false;
}
static bool __init hpet_counting(void)
{
u64 start, now, t1;
hpet_restart_counter();
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 {
if (t1 != hpet_readl(HPET_COUNTER))
return true;
now = rdtsc();
} while ((now - start) < 200000UL);
pr_warn("Counter not counting. HPET disabled\n");
return false;
}
static bool __init mwait_pc10_supported(void)
{
unsigned int eax, ebx, ecx, mwait_substates;
if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL)
return false;
if (!cpu_feature_enabled(X86_FEATURE_MWAIT))
return false;
if (boot_cpu_data.cpuid_level < CPUID_MWAIT_LEAF)
return false;
cpuid(CPUID_MWAIT_LEAF, &eax, &ebx, &ecx, &mwait_substates);
return (ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED) &&
(ecx & CPUID5_ECX_INTERRUPT_BREAK) &&
(mwait_substates & (0xF << 28));
}
/*
* Check whether the system supports PC10. If so force disable HPET as that
* stops counting in PC10. This check is overbroad as it does not take any
* of the following into account:
*
* - ACPI tables
* - Enablement of intel_idle
* - Command line arguments which limit intel_idle C-state support
*
* That's perfectly fine. HPET is a piece of hardware designed by committee
* and the only reasons why it is still in use on modern systems is the
* fact that it is impossible to reliably query TSC and CPU frequency via
* CPUID or firmware.
*
* If HPET is functional it is useful for calibrating TSC, but this can be
* done via PMTIMER as well which seems to be the last remaining timer on
* X86/INTEL platforms that has not been completely wreckaged by feature
* creep.
*
* In theory HPET support should be removed altogether, but there are older
* systems out there which depend on it because TSC and APIC timer are
* dysfunctional in deeper C-states.
*
* It's only 20 years now that hardware people have been asked to provide
* reliable and discoverable facilities which can be used for timekeeping
* and per CPU timer interrupts.
*
* The probability that this problem is going to be solved in the
* forseeable future is close to zero, so the kernel has to be cluttered
* with heuristics to keep up with the ever growing amount of hardware and
* firmware trainwrecks. Hopefully some day hardware people will understand
* that the approach of "This can be fixed in software" is not sustainable.
* Hope dies last...
*/
static bool __init hpet_is_pc10_damaged(void)
{
unsigned long long pcfg;
/* Check whether PC10 substates are supported */
if (!mwait_pc10_supported())
return false;
/* Check whether PC10 is enabled in PKG C-state limit */
rdmsrl(MSR_PKG_CST_CONFIG_CONTROL, pcfg);
if ((pcfg & 0xF) < 8)
return false;
if (hpet_force_user) {
pr_warn("HPET force enabled via command line, but dysfunctional in PC10.\n");
return false;
}
pr_info("HPET dysfunctional in PC10. Force disabled.\n");
boot_hpet_disable = true;
return true;
}
/**
* hpet_enable - Try to setup the HPET timer. Returns 1 on success.
*/
int __init hpet_enable(void)
{
u32 hpet_period, cfg, id, irq;
unsigned int i, channels;
struct hpet_channel *hc;
u64 freq;
if (!is_hpet_capable())
return 0;
if (hpet_is_pc10_damaged())
return 0;
hpet_set_mapping();
if (!hpet_virt_address)
return 0;
/* Validate that the config register is working */
if (!hpet_cfg_working())
goto out_nohpet;
/*
* Read the period and check for a sane value:
*/
hpet_period = hpet_readl(HPET_PERIOD);
if (hpet_period < HPET_MIN_PERIOD || hpet_period > HPET_MAX_PERIOD)
goto out_nohpet;
/* The period is a femtoseconds 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();
/* This is the HPET channel number which is zero based */
channels = ((id & HPET_ID_NUMBER) >> HPET_ID_NUMBER_SHIFT) + 1;
/*
* The legacy routing mode needs at least two channels, tick timer
* and the rtc emulation channel.
*/
if (IS_ENABLED(CONFIG_HPET_EMULATE_RTC) && channels < 2)
goto out_nohpet;
hc = kcalloc(channels, sizeof(*hc), GFP_KERNEL);
if (!hc) {
pr_warn("Disabling HPET.\n");
goto out_nohpet;
}
hpet_base.channels = hc;
hpet_base.nr_channels = channels;
/* Read, store and sanitize the global configuration */
cfg = hpet_readl(HPET_CFG);
hpet_base.boot_cfg = cfg;
cfg &= ~(HPET_CFG_ENABLE | HPET_CFG_LEGACY);
hpet_writel(cfg, HPET_CFG);
if (cfg)
pr_warn("Global config: Unknown bits %#x\n", cfg);
/* Read, store and sanitize the per channel configuration */
for (i = 0; i < channels; i++, hc++) {
hc->num = i;
cfg = hpet_readl(HPET_Tn_CFG(i));
hc->boot_cfg = cfg;
irq = (cfg & Tn_INT_ROUTE_CNF_MASK) >> Tn_INT_ROUTE_CNF_SHIFT;
hc->irq = irq;
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("Channel #%u config: Unknown bits %#x\n", i, cfg);
}
hpet_print_config();
/*
* Validate that the counter is counting. This needs to be done
* after sanitizing the config registers to properly deal with
* force enabled HPETs.
*/
if (!hpet_counting())
goto out_nohpet;
clocksource_register_hz(&clocksource_hpet, (u32)hpet_freq);
if (id & HPET_ID_LEGSUP) {
hpet_legacy_clockevent_register(&hpet_base.channels[0]);
hpet_base.channels[0].mode = HPET_MODE_LEGACY;
if (IS_ENABLED(CONFIG_HPET_EMULATE_RTC))
hpet_base.channels[1].mode = HPET_MODE_LEGACY;
return 1;
}
return 0;
out_nohpet:
kfree(hpet_base.channels);
hpet_base.channels = NULL;
hpet_base.nr_channels = 0;
hpet_clear_mapping();
hpet_address = 0;
return 0;
}
/*
* The late initialization runs after the PCI quirks have been invoked
* which might have detected a system on which the HPET can be enforced.
*
* Also, the MSI machinery is not working yet when the HPET is initialized
* early.
*
* If the HPET is enabled, then:
*
* 1) Reserve one channel for /dev/hpet if CONFIG_HPET=y
* 2) Reserve up to num_possible_cpus() channels as per CPU clockevents
* 3) Setup /dev/hpet if CONFIG_HPET=y
* 4) Register hotplug callbacks when clockevents are available
*/
static __init int hpet_late_init(void)
{
int ret;
if (!hpet_address) {
if (!force_hpet_address)
return -ENODEV;
hpet_address = force_hpet_address;
hpet_enable();
}
if (!hpet_virt_address)
return -ENODEV;
hpet_select_device_channel();
hpet_select_clockevents();
hpet_reserve_platform_timers();
hpet_print_config();
if (!hpet_base.nr_clockevents)
return 0;
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)
{
unsigned int i;
u32 cfg;
if (!is_hpet_capable() || !hpet_virt_address)
return;
/* Restore boot configuration with the enable bit cleared */
cfg = hpet_base.boot_cfg;
cfg &= ~HPET_CFG_ENABLE;
hpet_writel(cfg, HPET_CFG);
/* Restore the channel boot configuration */
for (i = 0; i < hpet_base.nr_channels; i++)
hpet_writel(hpet_base.channels[i].boot_cfg, HPET_Tn_CFG(i));
/* If the HPET was enabled at boot time, reenable it */
if (hpet_base.boot_cfg & HPET_CFG_ENABLE)
hpet_writel(hpet_base.boot_cfg, HPET_CFG);
}
#ifdef CONFIG_HPET_EMULATE_RTC
/*
* HPET in LegacyReplacement mode eats up the 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 second, when the
* 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 frequencies in powers of 2)
*
* (1) and (2) above are implemented using polling at a frequency of 64 Hz:
* DEFAULT_RTC_INT_FREQ.
*
* The exact frequency is a tradeoff between accuracy and interrupt overhead.
*
* For (3), we use interrupts at 64 Hz, or the user specified periodic frequency,
* if it's 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 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);
/*
* Channel 1 for RTC emulation. We use one shot mode, as periodic mode
* is not supported by all HPET implementations for channel 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) {
struct clock_event_device *evt = &hpet_base.channels[0].evt;
uint64_t clc;
clc = (uint64_t) evt->mult * NSEC_PER_SEC;
clc >>= evt->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 {
struct clock_event_device *evt = &hpet_base.channels[0].evt;
clc = (uint64_t) evt->mult * NSEC_PER_SEC;
do_div(clc, freq);
clc >>= evt->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())
pr_warn("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)) {
if (unlikely(mc146818_get_time(&curr_time) < 0)) {
pr_err_ratelimited("unable to read current time from RTC\n");
return IRQ_HANDLED;
}
}
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