hardware_riscv_platform_timer

Accessors for standard RISC-V platform timer (mtime/mtimecmp), available on Raspberry Pi microcontrollers with RISC-V processors. More...

Functions
static void	riscv_timer_set_enabled (bool enabled)
	Enable or disable the RISC-V platform timer. More...
static void	riscv_timer_set_fullspeed (bool fullspeed)
	Configure the RISC-V platform timer to run at full system clock speed. More...
static uint64_t	riscv_timer_get_mtime (void)
	Read the RISC-V platform timer. More...
static void	riscv_timer_set_mtime (uint64_t mtime)
	Update the RISC-V platform timer. More...
static uint64_t	riscv_timer_get_mtimecmp (void)
	Get the current RISC-V platform timer mtimecmp value for this core. More...
static void	riscv_timer_set_mtimecmp (uint64_t mtimecmp)
	Set a new RISC-V platform timer interrupt comparison value (mtimecmp) for this core. More...

Detailed Description

Accessors for standard RISC-V platform timer (mtime/mtimecmp), available on Raspberry Pi microcontrollers with RISC-V processors.

Note this header can be used by Arm as well as RISC-V processors, as the timer is a memory-mapped peripheral external to the processors. The name refers to this timer being a standard RISC-V peripheral.

Function Documentation

riscv_timer_get_mtime()

static uint64_t riscv_timer_get_mtime ( void  )

inlinestatic

Read the RISC-V platform timer.

Returns

Current 64-bit mtime value

riscv_timer_get_mtimecmp()

static uint64_t riscv_timer_get_mtimecmp ( void  )

inlinestatic

Get the current RISC-V platform timer mtimecmp value for this core.

Get the current mtimecmp value for the calling core. This function is interrupt-safe as long as timer interrupts only increase the value of mtimecmp. Otherwise, it must be called with timer interrupts disabled.

Returns

Current value of mtimecmp

riscv_timer_set_enabled()

static void riscv_timer_set_enabled ( bool  enabled )

inlinestatic

Enable or disable the RISC-V platform timer.

This enables and disables the counting of the RISC-V platform timer. It does not enable or disable the interrupts, which are asserted unconditionally when a given core's mtimecmp/mtimecmph registers are greater than the current 64-bit value of the mtime/mtimeh registers.

Parameters

enabled

Pass true to enable, false to disable

riscv_timer_set_fullspeed()

static void riscv_timer_set_fullspeed ( bool  fullspeed )

inlinestatic

Configure the RISC-V platform timer to run at full system clock speed.

Parameters

fullspeed

Pass true to increment at system clock speed, false to increment at the frequency defined by the system tick generator (the ticks block)

riscv_timer_set_mtime()

static void riscv_timer_set_mtime ( uint64_t  mtime )

inlinestatic

Update the RISC-V platform timer.

This function should only be called when the timer is disabled via riscv_timer_set_enabled(). Note also that unlike the mtimecmp comparison values, mtime is not core-local, so updates on one core will be visible to the other core.

Parameters

mtime

New value to set the RISC-V platform timer to

riscv_timer_set_mtimecmp()

static void riscv_timer_set_mtimecmp ( uint64_t  mtimecmp )

inlinestatic

Set a new RISC-V platform timer interrupt comparison value (mtimecmp) for this core.

This function updates the mtimecmp value for the current core. The calling core's RISC-V platform timer interrupt is asserted whenever the 64-bit mtime value (stored in 32-bit mtime/mtimeh registers) is greater than or equal to this core's current mtime/mtimecmph value.

Parameters

mtime

New value to set the RISC-V platform timer to