High Precision Event Timer. More...

Data Structures
struct	hpet_t
	High Precision Event Timer structure. More...

Macros
#define	HPET_CAP_COUNTER_CLK_PERIOD_SHIFT 32
	The bit offset of the clock period in the capabilities register.

#define	HPET_CONF_ENABLE_CNF_BIT (1 << 0)
	The bit to set to enable the HPET in the configuration register.

#define	HPET_CONF_LEG_RT_CNF_BIT (1 << 1)
	The bit to set to enable legacy replacement mode in the configuration register.

#define	HPET_ADDRESS_SPACE_MEMORY 0
	If `hpet_t::addressSpaceId` is equal to this, the address is in system memory space.

#define	HPET_ADDRESS_SPACE_IO 1
	If `hpet_t::addressSpaceId` is equal to this, the address is in system I/O space.

#define	HPET_FEMTOSECONDS_PER_SECOND 1000000000000000ULL
	The number of femtoseconds in one second.

Enumerations
enum	hpet_register_t { HPET_REG_GENERAL_CAPABILITIES_ID = 0x000 , HPET_REG_GENERAL_CONFIG = 0x010 , HPET_REG_GENERAL_INTERRUPT = 0x020 , HPET_REG_MAIN_COUNTER_VALUE = 0x0F0 , HPET_REG_TIMER0_CONFIG_CAP = 0x100 , HPET_REG_TIMER0_COMPARATOR = 0x108 }
	HPET register offsets. More...

Functions
static void	hpet_write (hpet_register_t reg, uint64_t value)
	Write to an HPET register.

static uint64_t	hpet_read (hpet_register_t reg)
	Read from an HPET register.

static clock_t	hpet_ns_per_tick (void)
	Get the HPET clock period in nanoseconds.

static clock_t	hpet_read_ns_counter (void)
	Safely read the HPET counter value in nanoseconds.

static void	hpet_reset_counter (void)
	Reset the HPET main counter to zero and enable the HPET.

static void	hpet_timer_handler (interrupt_frame_t frame, cpu_t self)
	Timer interrupt handler to avoid HPET counter overflows on 32-bit HPETs.

static uint64_t	hpet_init (void)
	Initialize the HPET.

static void	hpet_deinit (void)
	Deinitialize the HPET.

Variables
static hpet_t *	hpet
	Pointer to the HPET ACPI table.

static uintptr_t	address
	Mapped virtual address of the HPET registers.

static uint64_t	period
	Main counter tick period in femtoseconds (10^-15 s).

static atomic_uint64_t	counter = ATOMIC_VAR_INIT(0)
	Accumulated nanosecond counter, used to avoid overflows.

static seqlock_t	counterLock = SEQLOCK_CREATE
	Seqlock for the accumulated counter.

static sys_time_source_t	source
	Structure to describe the HPET to the sys time subsystem.

Detailed Description

High Precision Event Timer.

Note that since the HPET might be 32bit it could overflow rather quickly, so we implement a system for checking roughly when it will overflow and accumulate the counter into a 64 bit nanosecond counter.

See also: OSDev HPET

Macro Definition Documentation

◆ HPET_ADDRESS_SPACE_IO

#define HPET_ADDRESS_SPACE_IO 1

If hpet_t::addressSpaceId is equal to this, the address is in system I/O space.

Definition at line 62 of file hpet.c.

◆ HPET_ADDRESS_SPACE_MEMORY

#define HPET_ADDRESS_SPACE_MEMORY 0

If hpet_t::addressSpaceId is equal to this, the address is in system memory space.

Definition at line 57 of file hpet.c.

◆ HPET_CAP_COUNTER_CLK_PERIOD_SHIFT

#define HPET_CAP_COUNTER_CLK_PERIOD_SHIFT 32

The bit offset of the clock period in the capabilities register.

Definition at line 42 of file hpet.c.

◆ HPET_CONF_ENABLE_CNF_BIT

#define HPET_CONF_ENABLE_CNF_BIT (1 << 0)

The bit to set to enable the HPET in the configuration register.

Definition at line 47 of file hpet.c.

◆ HPET_CONF_LEG_RT_CNF_BIT

#define HPET_CONF_LEG_RT_CNF_BIT (1 << 1)

The bit to set to enable legacy replacement mode in the configuration register.

Definition at line 52 of file hpet.c.

◆ HPET_FEMTOSECONDS_PER_SECOND

#define HPET_FEMTOSECONDS_PER_SECOND 1000000000000000ULL

The number of femtoseconds in one second.

Definition at line 67 of file hpet.c.

Enumeration Type Documentation

◆ hpet_register_t

enum hpet_register_t

HPET register offsets.

Enumerator
HPET_REG_GENERAL_CAPABILITIES_ID
HPET_REG_GENERAL_CONFIG
HPET_REG_GENERAL_INTERRUPT
HPET_REG_MAIN_COUNTER_VALUE
HPET_REG_TIMER0_CONFIG_CAP
HPET_REG_TIMER0_COMPARATOR

Definition at line 29 of file hpet.c.

Function Documentation

◆ hpet_deinit()

static void hpet_deinit ( void )

static

Deinitialize the HPET.

Definition at line 248 of file hpet.c.

References HPET_REG_GENERAL_CONFIG, hpet_write(), source, and sys_time_unregister_source().

Referenced by _module_procedure().

◆ hpet_init()

static uint64_t hpet_init ( void )

static

Initialize the HPET.

Returns: On success, 0. On failure, ERR.

Definition at line 196 of file hpet.c.

References acpi_tables_lookup(), hpet_t::address, address, hpet_t::addressSpaceId, CLOCKS_PER_SEC, hpet_t::comparatorCount, hpet_t::counterIs64Bit, cpu_get_unsafe(), ERR, hpet, HPET_ADDRESS_SPACE_MEMORY, HPET_CAP_COUNTER_CLK_PERIOD_SHIFT, HPET_FEMTOSECONDS_PER_SECOND, hpet_ns_per_tick(), hpet_read(), HPET_REG_GENERAL_CAPABILITIES_ID, hpet_reset_counter(), hpet_timer_handler(), LOG_ERR, LOG_INFO, NULL, PAGE_SIZE, period, PML_GLOBAL, PML_LOWER_TO_HIGHER, PML_PRESENT, PML_WRITE, sys_time_source_t::precision, source, sys_time_register_source(), and vmm_map().

Referenced by _module_procedure().

◆ hpet_ns_per_tick()

static clock_t hpet_ns_per_tick ( void )

inlinestatic

Get the HPET clock period in nanoseconds.

Returns: The HPET clock period in nanoseconds.

Definition at line 126 of file hpet.c.

References CLOCKS_PER_SEC, HPET_FEMTOSECONDS_PER_SECOND, and period.

Referenced by hpet_init(), hpet_read_ns_counter(), and hpet_timer_handler().

◆ hpet_read()

static uint64_t hpet_read ( hpet_register_t reg )

inlinestatic

Read from an HPET register.

Parameters

reg	The register to read from.

Returns: The value read from the register.

Definition at line 116 of file hpet.c.

References address, and READ_64.

Referenced by hpet_init(), hpet_read_ns_counter(), and hpet_timer_handler().

◆ hpet_read_ns_counter()

static clock_t hpet_read_ns_counter ( void )

static

Safely read the HPET counter value in nanoseconds.

Returns: The current value of the HPET counter in nanoseconds.

Definition at line 136 of file hpet.c.

References atomic_load, counter, counterLock, hpet_ns_per_tick(), hpet_read(), HPET_REG_MAIN_COUNTER_VALUE, seqlock_read_begin(), seqlock_read_retry(), and time().

◆ hpet_reset_counter()

static void hpet_reset_counter ( void )

inlinestatic

Reset the HPET main counter to zero and enable the HPET.

Definition at line 151 of file hpet.c.

References HPET_CONF_ENABLE_CNF_BIT, HPET_REG_GENERAL_CONFIG, HPET_REG_MAIN_COUNTER_VALUE, and hpet_write().

Referenced by hpet_init(), and hpet_timer_handler().

◆ hpet_timer_handler()

static void hpet_timer_handler	(	interrupt_frame_t *	frame,
		cpu_t *	self
	)

static

Timer interrupt handler to avoid HPET counter overflows on 32-bit HPETs.

Is also used for 64-bit HPETs but it will in practice never fire.

Parameters

frame	The interrupt frame.
self	The current CPU.

Definition at line 166 of file hpet.c.

References atomic_fetch_add, counter, counterLock, hpet_ns_per_tick(), hpet_read(), HPET_REG_MAIN_COUNTER_VALUE, hpet_reset_counter(), LOG_INFO, seqlock_write_acquire(), seqlock_write_release(), sys_time_uptime(), timer_one_shot(), and UINT32_MAX.

Referenced by hpet_init().

◆ hpet_write()

static void hpet_write	(	hpet_register_t	reg,
		uint64_t	value
	)

inlinestatic

Write to an HPET register.

Parameters

reg	The register to write to.
value	The value to write.

Definition at line 105 of file hpet.c.

References address, and WRITE_64.

Referenced by hpet_deinit(), and hpet_reset_counter().

Variable Documentation

◆ address

uintptr_t address

static

Mapped virtual address of the HPET registers.

Definition at line 93 of file hpet.c.

Referenced by _syscall_mmap(), _syscall_mprotect(), _syscall_munmap(), aml_ensure_mem_is_mapped(), aml_generic_field_read_at(), aml_generic_field_write_at(), aml_opregion_read(), aml_opregion_write(), aml_pci_config_read(), aml_pci_config_write(), aml_system_io_read(), aml_system_io_write(), aml_system_mem_read(), aml_system_mem_write(), hpet_init(), hpet_read(), hpet_write(), local_listen_find(), local_listen_new(), local_socket_bind(), local_socket_connect(), mmap(), mprotect(), munmap(), page_table_page_buffer_push(), pci_config_get_address(), pmm_alloc(), pmm_alloc_bitmap(), pmm_alloc_pages(), pmm_bitmap_free(), pmm_free(), pmm_free_pages_unlocked(), pmm_free_region(), pmm_free_unlocked(), pmm_stack_alloc(), pmm_stack_free(), shmem_mmap(), shmem_object_allocate_pages(), space_pin_depth_dec(), space_pin_depth_inc(), space_pin_terminated(), space_unpin(), SYSCALL_DEFINE(), SYSCALL_DEFINE(), SYSCALL_DEFINE(), and vfs_mmap().

◆ counter

atomic_uint64_t counter = ATOMIC_VAR_INIT(0)

static

Accumulated nanosecond counter, used to avoid overflows.

Definition at line 96 of file hpet.c.

Referenced by hpet_read_ns_counter(), and hpet_timer_handler().

◆ counterLock

seqlock_t counterLock = SEQLOCK_CREATE

static

Seqlock for the accumulated counter.

Definition at line 97 of file hpet.c.

Referenced by hpet_read_ns_counter(), and hpet_timer_handler().

◆ hpet

hpet_t* hpet

static

Pointer to the HPET ACPI table.

Definition at line 92 of file hpet.c.

Referenced by hpet_init().

◆ period

uint64_t period

static

Main counter tick period in femtoseconds (10^-15 s).

Definition at line 94 of file hpet.c.

Referenced by hpet_init(), and hpet_ns_per_tick().

◆ source

sys_time_source_t source

static

Initial value:

= {
    .name = "HPET",
    .precision = 0, 
    .read = hpet_read_ns_counter,
}

Structure to describe the HPET to the sys time subsystem.

Definition at line 185 of file hpet.c.

Referenced by _syscall_bind(), aml_concat_resolve_to_buffer(), aml_concat_resolve_to_integer(), aml_concat_resolve_to_string(), aml_def_alias_read(), aml_def_cond_ref_of_read(), aml_def_copy_object_read(), aml_def_decrement_read(), aml_def_increment_read(), aml_def_store_read(), aml_def_to_string_read(), bind(), hpet_deinit(), hpet_init(), namespace_bind(), sys_time_register_source(), sys_time_unregister_source(), and SYSCALL_DEFINE().

Data Structures

Macros

Enumerations

Functions

Variables

Detailed Description

Macro Definition Documentation

◆ HPET_ADDRESS_SPACE_IO

◆ HPET_ADDRESS_SPACE_MEMORY

◆ HPET_CAP_COUNTER_CLK_PERIOD_SHIFT

◆ HPET_CONF_ENABLE_CNF_BIT

◆ HPET_CONF_LEG_RT_CNF_BIT

◆ HPET_FEMTOSECONDS_PER_SECOND

Enumeration Type Documentation

◆ hpet_register_t

Function Documentation

◆ hpet_deinit()

◆ hpet_init()

◆ hpet_ns_per_tick()

◆ hpet_read()

◆ hpet_read_ns_counter()

◆ hpet_reset_counter()

◆ hpet_timer_handler()

◆ hpet_write()

Variable Documentation

◆ address

◆ counter

◆ counterLock

◆ hpet

◆ period

◆ source