[PATCH V4 07/14] LoongArch: Adjust time routines for 32BIT/64BIT

Huacai Chen
2025-11-27T15:53:45Z

Adjust time routines for both 32BIT and 64BIT, including: rdtime_h() /
rdtime_l() definitions for 32BIT and rdtime_d() definition for 64BIT,
get_cycles() and get_cycles64() definitions for 32BIT/64BIT, show time
frequency info ("CPU MHz" and "BogoMIPS") in /proc/cpuinfo, etc.

Use do_div() for division which works on both 32BIT and 64BIT platforms.

Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
---
arch/loongarch/include/asm/loongarch.h | 32 ++++++++++++++++++++++++-
arch/loongarch/include/asm/timex.h | 33 +++++++++++++++++++++++++-
arch/loongarch/kernel/proc.c | 10 ++++----
arch/loongarch/kernel/syscall.c | 2 +-
arch/loongarch/kernel/time.c | 15 ++++++------
arch/loongarch/kvm/vcpu.c | 5 ++--
6 files changed, 80 insertions(+), 17 deletions(-)

diff --git a/arch/loongarch/include/asm/loongarch.h b/arch/loongarch/include/asm/loongarch.h
index 804341bd8d2e..19e3f2c183fe 100644
--- a/arch/loongarch/include/asm/loongarch.h
+++ b/arch/loongarch/include/asm/loongarch.h
@@ -1238,7 +1238,35 @@

#ifndef __ASSEMBLER__

-static __always_inline u64 drdtime(void)
+#ifdef CONFIG_32BIT
+
+static __always_inline u32 rdtime_h(void)
+{
+ u32 val = 0;
+
+ __asm__ __volatile__(
+ "rdtimeh.w %0, $zero\n\t"
+ : "=r"(val)
+ :
+ );
+ return val;
+}
+
+static __always_inline u32 rdtime_l(void)
+{
+ u32 val = 0;
+
+ __asm__ __volatile__(
+ "rdtimel.w %0, $zero\n\t"
+ : "=r"(val)
+ :
+ );
+ return val;
+}
+
+#else
+
+static __always_inline u64 rdtime_d(void)
{
u64 val = 0;

@@ -1250,6 +1278,8 @@ static __always_inline u64 drdtime(void)
return val;
}

+#endif
+
static inline unsigned int get_csr_cpuid(void)
{
return csr_read32(LOONGARCH_CSR_CPUID);
diff --git a/arch/loongarch/include/asm/timex.h b/arch/loongarch/include/asm/timex.h
index fb41e9e7a222..9ea52fad9690 100644
--- a/arch/loongarch/include/asm/timex.h
+++ b/arch/loongarch/include/asm/timex.h
@@ -18,7 +18,38 @@ typedef unsigned long cycles_t;

static inline cycles_t get_cycles(void)
{
- return drdtime();
+#ifdef CONFIG_32BIT
+ return rdtime_l();
+#else
+ return rdtime_d();
+#endif
+}
+
+#ifdef CONFIG_32BIT
+
+#define get_cycles_hi get_cycles_hi
+
+static inline cycles_t get_cycles_hi(void)
+{
+ return rdtime_h();
+}
+
+#endif
+
+static inline u64 get_cycles64(void)
+{
+#ifdef CONFIG_32BIT
+ u32 hi, lo;
+
+ do {
+ hi = rdtime_h();
+ lo = rdtime_l();
+ } while (hi != rdtime_h());
+
+ return ((u64)hi << 32) | lo;
+#else
+ return rdtime_d();
+#endif
}

#endif /* __KERNEL__ */
diff --git a/arch/loongarch/kernel/proc.c b/arch/loongarch/kernel/proc.c
index 63d2b7e7e844..a8800d20e11b 100644
--- a/arch/loongarch/kernel/proc.c
+++ b/arch/loongarch/kernel/proc.c
@@ -20,11 +20,14 @@ static int show_cpuinfo(struct seq_file *m, void *v)
unsigned int prid = cpu_data[n].processor_id;
unsigned int version = cpu_data[n].processor_id & 0xff;
unsigned int fp_version = cpu_data[n].fpu_vers;
+ u64 freq = cpu_clock_freq, bogomips = lpj_fine * cpu_clock_freq;

#ifdef CONFIG_SMP
if (!cpu_online(n))
return 0;
#endif
+ do_div(freq, 10000);
+ do_div(bogomips, const_clock_freq * (5000/HZ));

/*
* For the first processor also print the system type
@@ -41,11 +44,8 @@ static int show_cpuinfo(struct seq_file *m, void *v)
seq_printf(m, "PRID\t\t\t: %s (%08x)\n", id_to_core_name(prid), prid);
seq_printf(m, "CPU Revision\t\t: 0x%02x\n", version);
seq_printf(m, "FPU Revision\t\t: 0x%02x\n", fp_version);
- seq_printf(m, "CPU MHz\t\t\t: %llu.%02llu\n",
- cpu_clock_freq / 1000000, (cpu_clock_freq / 10000) % 100);
- seq_printf(m, "BogoMIPS\t\t: %llu.%02llu\n",
- (lpj_fine * cpu_clock_freq / const_clock_freq) / (500000/HZ),
- ((lpj_fine * cpu_clock_freq / const_clock_freq) / (5000/HZ)) % 100);
+ seq_printf(m, "CPU MHz\t\t\t: %u.%02u\n", (u32)freq / 100, (u32)freq % 100);
+ seq_printf(m, "BogoMIPS\t\t: %u.%02u\n", (u32)bogomips / 100, (u32)bogomips % 100);
seq_printf(m, "TLB Entries\t\t: %d\n", cpu_data[n].tlbsize);
seq_printf(m, "Address Sizes\t\t: %d bits physical, %d bits virtual\n",
cpu_pabits + 1, cpu_vabits + 1);
diff --git a/arch/loongarch/kernel/syscall.c b/arch/loongarch/kernel/syscall.c
index 168bd97540f8..ab94eb5ce039 100644
--- a/arch/loongarch/kernel/syscall.c
+++ b/arch/loongarch/kernel/syscall.c
@@ -75,7 +75,7 @@ void noinstr __no_stack_protector do_syscall(struct pt_regs *regs)
*
* The resulting 6 bits of entropy is seen in SP[9:4].
*/
- choose_random_kstack_offset(drdtime());
+ choose_random_kstack_offset(get_cycles());

syscall_exit_to_user_mode(regs);
}
diff --git a/arch/loongarch/kernel/time.c b/arch/loongarch/kernel/time.c
index 1c31bf3a16ed..5892f6da07a5 100644
--- a/arch/loongarch/kernel/time.c
+++ b/arch/loongarch/kernel/time.c
@@ -18,6 +18,7 @@
#include <asm/loongarch.h>
#include <asm/paravirt.h>
#include <asm/time.h>
+#include <asm/timex.h>

u64 cpu_clock_freq;
EXPORT_SYMBOL(cpu_clock_freq);
@@ -62,12 +63,12 @@ static int constant_set_state_oneshot(struct clock_event_device *evt)

static int constant_set_state_periodic(struct clock_event_device *evt)
{
- unsigned long period;
unsigned long timer_config;
+ u64 period = const_clock_freq;

raw_spin_lock(&state_lock);

- period = const_clock_freq / HZ;
+ do_div(period, HZ);
timer_config = period & CSR_TCFG_VAL;
timer_config |= (CSR_TCFG_PERIOD | CSR_TCFG_EN);
csr_write(timer_config, LOONGARCH_CSR_TCFG);
@@ -120,7 +121,7 @@ static int arch_timer_dying(unsigned int cpu)

static unsigned long get_loops_per_jiffy(void)
{
- unsigned long lpj = (unsigned long)const_clock_freq;
+ u64 lpj = const_clock_freq;

do_div(lpj, HZ);

@@ -131,7 +132,7 @@ static long init_offset;

void save_counter(void)
{
- init_offset = drdtime();
+ init_offset = get_cycles();
}

void sync_counter(void)
@@ -197,12 +198,12 @@ int constant_clockevent_init(void)

static u64 read_const_counter(struct clocksource *clk)
{
- return drdtime();
+ return get_cycles64();
}

static noinstr u64 sched_clock_read(void)
{
- return drdtime();
+ return get_cycles64();
}

static struct clocksource clocksource_const = {
@@ -235,7 +236,7 @@ void __init time_init(void)
else
const_clock_freq = calc_const_freq();

- init_offset = -(drdtime() - csr_read(LOONGARCH_CSR_CNTC));
+ init_offset = -(get_cycles() - csr_read(LOONGARCH_CSR_CNTC));

constant_clockevent_init();
constant_clocksource_init();
diff --git a/arch/loongarch/kvm/vcpu.c b/arch/loongarch/kvm/vcpu.c
index 1245a6b35896..803224d297eb 100644
--- a/arch/loongarch/kvm/vcpu.c
+++ b/arch/loongarch/kvm/vcpu.c
@@ -9,6 +9,7 @@
#include <asm/loongarch.h>
#include <asm/setup.h>
#include <asm/time.h>
+#include <asm/timex.h>

#define CREATE_TRACE_POINTS
#include "trace.h"
@@ -811,7 +812,7 @@ static int kvm_get_one_reg(struct kvm_vcpu *vcpu,
case KVM_REG_LOONGARCH_KVM:
switch (reg->id) {
case KVM_REG_LOONGARCH_COUNTER:
- *v = drdtime() + vcpu->kvm->arch.time_offset;
+ *v = get_cycles() + vcpu->kvm->arch.time_offset;
break;
case KVM_REG_LOONGARCH_DEBUG_INST:
*v = INSN_HVCL | KVM_HCALL_SWDBG;
@@ -906,7 +907,7 @@ static int kvm_set_one_reg(struct kvm_vcpu *vcpu,
* only set for the first time for smp system
*/
if (vcpu->vcpu_id == 0)
- vcpu->kvm->arch.time_offset = (signed long)(v - drdtime());
+ vcpu->kvm->arch.time_offset = (signed long)(v - get_cycles());
break;
case KVM_REG_LOONGARCH_VCPU_RESET:
vcpu->arch.st.guest_addr = 0;
--
2.47.3