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clocksource/drivers/timer-sp804: Fix read_current_timer() issue when clock source is not registered 

Register a valid read_current_timer() function for the
SP804 timer on ARM32.

On ARM32 platforms, when the SP804 timer is selected as the clocksource,
the driver does not register a valid read_current_timer() function.
As a result, features that rely on this API—such as rdseed—consistently
return incorrect values.

To fix this, a delay_timer structure is registered during the SP804
driver's initialization. The read_current_timer() function is implemented
using the existing sp804_read() logic, and the timer frequency is reused
from the already-initialized clocksource.

Signed-off-by: Stephen Eta Zhou <stephen.eta.zhou@gmail.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://patch.msgid.link/20250525-sp804-fix-read_current_timer-v4-1-87a9201fa4ec@gmail.com
This commit is contained in:
Stephen Eta Zhou 2025-05-25 16:43:28 +08:00 committed by Daniel Lezcano
parent 576c564ec3
commit 640594a04f
1 changed files with 24 additions and 0 deletions
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24
drivers/clocksource/timer-sp804.c
View File

@ -21,6 +21,10 @@
#include <linux/of_irq.h>
#include <linux/sched_clock.h>
#ifdef CONFIG_ARM
#include <linux/delay.h>
#endif
#include "timer-sp.h"
/* Hisilicon 64-bit timer(a variant of ARM SP804) */
@ -102,6 +106,23 @@ static u64 notrace sp804_read(void)
return ~readl_relaxed(sched_clkevt->value);
}
#ifdef CONFIG_ARM
static struct delay_timer delay;
static unsigned long sp804_read_delay_timer_read(void)
{
return sp804_read();
}
static void sp804_register_delay_timer(int freq)
{
delay.freq = freq;
delay.read_current_timer = sp804_read_delay_timer_read;
register_current_timer_delay(&delay);
}
#else
static inline void sp804_register_delay_timer(int freq) {}
#endif
static int __init sp804_clocksource_and_sched_clock_init(void __iomem *base,
const char *name,
struct clk *clk,
@ -114,6 +135,8 @@ static int __init sp804_clocksource_and_sched_clock_init(void __iomem *base,
if (rate < 0)
return -EINVAL;
sp804_register_delay_timer(rate);
clkevt = sp804_clkevt_get(base);
writel(0, clkevt->ctrl);
@ -318,6 +341,7 @@ static int __init sp804_of_init(struct device_node *np, struct sp804_timer *time
if (ret)
goto err;
}
initialized = true;
return 0;