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lib: sbi: Add generic timer delay loop function

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We now have frequency of the timer device provided by the platform
support so we can emulate desired delay using a loop where the number
loop iterations are based on timer frequency.

This patch provides sbi_timer_delay_loop() for above purpose.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Xiang W <wxjstz@126.com>
This commit is contained in:
Anup Patel
2021-09-15 10:11:24 +05:30
committed by Anup Patel
parent 6355155f51
commit 9d0ab35ab4
2 changed files with 50 additions and 0 deletions
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16
include/sbi/sbi_timer.h
View File

@@ -32,6 +32,22 @@ struct sbi_timer_device {
struct sbi_scratch; struct sbi_scratch;
/** Generic delay loop of desired granularity */
void sbi_timer_delay_loop(ulong units, u64 unit_freq,
void (*delay_fn)(void *), void *opaque);
/** Provide delay in terms of milliseconds */
static inline void sbi_timer_mdelay(ulong msecs)
{
sbi_timer_delay_loop(msecs, 1000, NULL, NULL);
}
/** Provide delay in terms of microseconds */
static inline void sbi_timer_udelay(ulong usecs)
{
sbi_timer_delay_loop(usecs, 1000000, NULL, NULL);
}
/** Get timer value for current HART */ /** Get timer value for current HART */
u64 sbi_timer_value(void); u64 sbi_timer_value(void);

34
lib/sbi/sbi_timer.c
View File

@@ -8,7 +8,9 @@
*/ */
#include <sbi/riscv_asm.h> #include <sbi/riscv_asm.h>
#include <sbi/riscv_barrier.h>
#include <sbi/riscv_encoding.h> #include <sbi/riscv_encoding.h>
#include <sbi/sbi_console.h>
#include <sbi/sbi_error.h> #include <sbi/sbi_error.h>
#include <sbi/sbi_hart.h> #include <sbi/sbi_hart.h>
#include <sbi/sbi_platform.h> #include <sbi/sbi_platform.h>
@@ -47,6 +49,38 @@ static u64 get_platform_ticks(void)
return timer_dev->timer_value(); return timer_dev->timer_value();
} }
static void nop_delay_fn(void *opaque)
{
cpu_relax();
}
void sbi_timer_delay_loop(ulong units, u64 unit_freq,
void (*delay_fn)(void *), void *opaque)
{
u64 start_val, delta;
/* Do nothing if we don't have timer device */
if (!timer_dev || !get_time_val) {
sbi_printf("%s: called without timer device\n", __func__);
return;
}
/* Save starting timer value */
start_val = get_time_val();
/* Compute desired timer value delta */
delta = ((u64)timer_dev->timer_freq * (u64)units);
delta = delta / unit_freq;
/* Use NOP delay function if delay function not available */
if (!delay_fn)
delay_fn = nop_delay_fn;
/* Busy loop until desired timer value delta reached */
while ((get_time_val() - start_val) < delta)
delay_fn(opaque);
}
u64 sbi_timer_value(void) u64 sbi_timer_value(void)
{ {
if (get_time_val) if (get_time_val)