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LoongArch: Derive timer max_delta from PRCFG1's timer_bits

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As per arch spec, maximum timer bits is configurable and should not be
hardcoded in any way.

Probe timer bits from PRCFG1 and use that to determine the clockevent's
max_delta to be conformance.

Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
This commit is contained in:
Jiaxun Yang 2025-01-25 18:51:33 +08:00 • committed by Huacai Chen
parent 341cf992d3
commit 98e720f77d
4 changed files with 3 additions and 2 deletions
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1
arch/loongarch/include/asm/cpu-info.h
View file

@ -57,6 +57,7 @@ struct cpuinfo_loongarch {
int global_id; /* physical global thread number */
int vabits; /* Virtual Address size in bits */
int pabits; /* Physical Address size in bits */
int timerbits; /* Width of arch timer in bits */
unsigned int ksave_mask; /* Usable KSave mask. */
unsigned int watch_dreg_count; /* Number data breakpoints */
unsigned int watch_ireg_count; /* Number instruction breakpoints */

1
arch/loongarch/include/asm/loongarch.h
View file

@ -466,7 +466,6 @@
#define LOONGARCH_CSR_TCFG 0x41 /* Timer config */
#define CSR_TCFG_VAL_SHIFT 2
#define CSR_TCFG_VAL_WIDTH 48
#define CSR_TCFG_VAL (_ULCAST_(0x3fffffffffff) << CSR_TCFG_VAL_SHIFT)
#define CSR_TCFG_PERIOD_SHIFT 1
#define CSR_TCFG_PERIOD (_ULCAST_(0x1) << CSR_TCFG_PERIOD_SHIFT)

1
arch/loongarch/kernel/cpu-probe.c
View file

@ -190,6 +190,7 @@ static void cpu_probe_common(struct cpuinfo_loongarch *c)
set_cpu_asid_mask(c, asid_mask);
config = read_csr_prcfg1();
c->timerbits = (config & CSR_CONF1_TMRBITS) >> CSR_CONF1_TMRBITS_SHIFT;
c->ksave_mask = GENMASK((config & CSR_CONF1_KSNUM) - 1, 0);
c->ksave_mask &= ~(EXC_KSAVE_MASK | PERCPU_KSAVE_MASK | KVM_KSAVE_MASK);

2
arch/loongarch/kernel/time.c
View file

@ -132,7 +132,7 @@ int constant_clockevent_init(void)
#else
unsigned long min_delta = 1000;
#endif
unsigned long max_delta = (1UL << 48) - 1;
unsigned long max_delta = GENMASK_ULL(boot_cpu_data.timerbits, 0);
struct clock_event_device *cd;
static int irq = 0, timer_irq_installed = 0;