diff options
Diffstat (limited to 'arch/x86/kernel/hpet.c')
| -rw-r--r-- | arch/x86/kernel/hpet.c | 1471 |
1 files changed, 1471 insertions, 0 deletions
diff --git a/arch/x86/kernel/hpet.c b/arch/x86/kernel/hpet.c new file mode 100644 index 000000000..54732da52 --- /dev/null +++ b/arch/x86/kernel/hpet.c @@ -0,0 +1,1471 @@ +// 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, 10) < 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 |