106 lines
3.2 KiB
C
106 lines
3.2 KiB
C
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/*
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* Arm SSE Subsystem System Counter
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*
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* Copyright (c) 2020 Linaro Limited
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* Written by Peter Maydell
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 or
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* (at your option) any later version.
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*/
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/*
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* This is a model of the "System counter" which is documented in
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* the Arm SSE-123 Example Subsystem Technical Reference Manual:
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* https://developer.arm.com/documentation/101370/latest/
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*
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* QEMU interface:
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* + Clock input "CLK": clock
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* + sysbus MMIO region 0: the control register frame
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* + sysbus MMIO region 1: the status register frame
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*
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* Consumers of the system counter's timestamp, such as the SSE
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* System Timer device, can also use the APIs sse_counter_for_timestamp(),
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* sse_counter_tick_to_time() and sse_counter_register_consumer() to
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* interact with an instance of the System Counter. Generally the
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* consumer device should have a QOM link property which the board
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* code can set to the appropriate instance of the system counter.
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*/
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#ifndef SSE_COUNTER_H
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#define SSE_COUNTER_H
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#include "hw/sysbus.h"
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#include "qom/object.h"
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#include "qemu/notify.h"
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#define TYPE_SSE_COUNTER "sse-counter"
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OBJECT_DECLARE_SIMPLE_TYPE(SSECounter, SSE_COUNTER)
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struct SSECounter {
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/*< private >*/
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SysBusDevice parent_obj;
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/*< public >*/
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MemoryRegion control_mr;
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MemoryRegion status_mr;
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Clock *clk;
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NotifierList notifier_list;
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uint32_t cntcr;
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uint32_t cntscr0;
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/*
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* These are used for handling clock frequency changes: they are a
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* tuple of (QEMU_CLOCK_VIRTUAL timestamp, CNTCV at that time),
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* taken when the clock frequency changes. sse_cntcv() needs them
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* to calculate the current CNTCV.
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*/
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uint64_t ns_then;
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uint64_t ticks_then;
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};
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/*
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* These functions are the interface by which a consumer of
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* the system timestamp (such as the SSE system timer device)
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* can communicate with the SSECounter.
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*/
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/**
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* sse_counter_for_timestamp:
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* @counter: SSECounter
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* @ns: timestamp of QEMU_CLOCK_VIRTUAL in nanoseconds
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*
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* Returns the value of the timestamp counter at the specified
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* point in time (assuming that no changes to scale factor, enable, etc
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* happen in the meantime).
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*/
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uint64_t sse_counter_for_timestamp(SSECounter *counter, uint64_t ns);
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/**
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* sse_counter_tick_to_time:
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* @counter: SSECounter
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* @tick: tick value
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*
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* Returns the time (a QEMU_CLOCK_VIRTUAL timestamp in nanoseconds)
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* when the timestamp counter will reach the specified tick count.
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* If the counter is not currently running, returns UINT64_MAX.
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*/
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uint64_t sse_counter_tick_to_time(SSECounter *counter, uint64_t tick);
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/**
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* sse_counter_register_consumer:
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* @counter: SSECounter
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* @notifier: Notifier which is notified on counter changes
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*
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* Registers @notifier with the SSECounter. When the counter's
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* configuration changes in a way that might invalidate information
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* previously returned via sse_counter_for_timestamp() or
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* sse_counter_tick_to_time(), the notifier will be called.
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* Devices which consume the timestamp counter can use this as
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* a cue to recalculate timer events.
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*/
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void sse_counter_register_consumer(SSECounter *counter, Notifier *notifier);
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#endif
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