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https://github.com/riscv-software-src/opensbi.git
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994c8cfb29
Motivation: Suppose a peripheral needs to be configured to transmit data. There is an SFR bit which indicates that the peripheral is ready to transmit. The firmware should check the bit and will only transmit data when the peripheral is ready. When the firmware starts polling the SFR, the peripheral could be busy transmitting/receiving other data so the firmware must wait till that completes. Assuming that there is no other way, the firmware shouldn't wait indefinitely. The function sbi_timer_waitms_until() will constantly check whether a certain condition is satisfied, or timeout occurs. It can be used for the cases when a timeout is required. Signed-off-by: Adnan Rahman Chowdhury <adnan.chowdhury@sifive.com> Reviewed-by: Xiang W <wxjstz@126.com> Reviewed-by: Anup Patel <anup@brainfault.org>
103 lines
2.7 KiB
C
103 lines
2.7 KiB
C
/*
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* SPDX-License-Identifier: BSD-2-Clause
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*
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* Copyright (c) 2019 Western Digital Corporation or its affiliates.
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*
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* Authors:
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* Anup Patel <anup.patel@wdc.com>
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*/
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#ifndef __SBI_TIMER_H__
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#define __SBI_TIMER_H__
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#include <sbi/sbi_types.h>
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/** Timer hardware device */
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struct sbi_timer_device {
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/** Name of the timer operations */
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char name[32];
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/** Frequency of timer in HZ */
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unsigned long timer_freq;
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/** Get free-running timer value */
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u64 (*timer_value)(void);
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/** Start timer event for current HART */
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void (*timer_event_start)(u64 next_event);
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/** Stop timer event for current HART */
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void (*timer_event_stop)(void);
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};
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struct sbi_scratch;
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/** Generic delay loop of desired granularity */
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void sbi_timer_delay_loop(ulong units, u64 unit_freq,
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void (*delay_fn)(void *), void *opaque);
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/** Provide delay in terms of milliseconds */
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static inline void sbi_timer_mdelay(ulong msecs)
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{
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sbi_timer_delay_loop(msecs, 1000, NULL, NULL);
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}
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/** Provide delay in terms of microseconds */
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static inline void sbi_timer_udelay(ulong usecs)
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{
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sbi_timer_delay_loop(usecs, 1000000, NULL, NULL);
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}
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/**
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* A blocking function that will wait until @p predicate returns true or
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* @p timeout_ms milliseconds elapsed. @p arg will be passed as argument to
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* @p predicate function.
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*
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* @param predicate Pointer to a function that returns true if certain
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* condition is met. It shouldn't block the code execution.
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* @param arg Argument to pass to @p predicate.
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* @param timeout_ms Timeout value in milliseconds. The function will return
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* false if @p timeout_ms time period elapsed but still @p predicate doesn't
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* return true.
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*
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* @return true if @p predicate returns true within @p timeout_ms, false
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* otherwise.
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*/
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bool sbi_timer_waitms_until(bool (*predicate)(void *), void *arg,
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uint64_t timeout_ms);
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/** Get timer value for current HART */
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u64 sbi_timer_value(void);
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/** Get virtualized timer value for current HART */
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u64 sbi_timer_virt_value(void);
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/** Get timer delta value for current HART */
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u64 sbi_timer_get_delta(void);
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/** Set timer delta value for current HART */
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void sbi_timer_set_delta(ulong delta);
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/** Set upper 32-bits of timer delta value for current HART */
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void sbi_timer_set_delta_upper(ulong delta_upper);
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/** Start timer event for current HART */
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void sbi_timer_event_start(u64 next_event);
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/** Process timer event for current HART */
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void sbi_timer_process(void);
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/** Get current timer device */
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const struct sbi_timer_device *sbi_timer_get_device(void);
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/** Register timer device */
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void sbi_timer_set_device(const struct sbi_timer_device *dev);
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/* Initialize timer */
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int sbi_timer_init(struct sbi_scratch *scratch, bool cold_boot);
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/* Exit timer */
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void sbi_timer_exit(struct sbi_scratch *scratch);
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#endif
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