clocksource/drivers/timer-riscv: Clear timer interrupt on timer initialization

In the RISC-V specification, the stimecmp register doesn't have a default
value. To prevent the timer interrupt from being triggered during timer
initialization, clear the timer interrupt by writing stimecmp with a
maximum value.

Fixes: 9f7a8ff ("RISC-V: Prefer sstc extension if available")
Cc: <stable@vger.kernel.org>
Signed-off-by: Ley Foon Tan <leyfoon.tan@starfivetech.com>
Reviewed-by: Samuel Holland <samuel.holland@sifive.com>
Tested-by: Samuel Holland <samuel.holland@sifive.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20240306172330.255844-1-leyfoon.tan@starfivetech.com

Author: Ley Foon Tan

drivers/clocksource/timer-riscv.c

@@ -108,6 +108,9 @@ static int riscv_timer_starting_cpu(unsigned int cpu)
 {
 	struct clock_event_device *ce = per_cpu_ptr(&riscv_clock_event, cpu);
 
+	/* Clear timer interrupt */
+	riscv_clock_event_stop();
+
 	ce->cpumask = cpumask_of(cpu);
 	ce->irq = riscv_clock_event_irq;
 	if (riscv_timer_cannot_wake_cpu)