Re: [PATCH] MIPS: cevt-r4k: Enable intimer for Loongson64 CPUs with extimer

From: Paul Cercueil
Date: Sun Oct 04 2020 - 16:50:19 EST


Hi,

Le mer. 23 sept. 2020 à 19:02, Jiaxun Yang <jiaxun.yang@xxxxxxxxxxx> a écrit :
Loongson64C and Loongson64G have extimer feature, which is a
timer sharing Cause.TI with cevt-r4k (named intimer).

To ensure the cevt-r4k's usability, we need to add a callback for
clock device to switch intimer.

Signed-off-by: Jiaxun Yang <jiaxun.yang@xxxxxxxxxxx>
---
arch/mips/include/asm/cpu-features.h | 4 ++++
arch/mips/include/asm/cpu.h | 1 +
arch/mips/kernel/cevt-r4k.c | 25 +++++++++++++++++++++++++
arch/mips/kernel/cpu-probe.c | 6 +++++-
4 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/arch/mips/include/asm/cpu-features.h b/arch/mips/include/asm/cpu-features.h
index 78cf7e300f12..aec458eee2a5 100644
--- a/arch/mips/include/asm/cpu-features.h
+++ b/arch/mips/include/asm/cpu-features.h
@@ -576,6 +576,10 @@
# define cpu_has_gsexcex __opt(MIPS_CPU_GSEXCEX)
#endif

+#ifndef cpu_has_extimer
+# define cpu_has_extimer __opt(MIPS_CPU_EXTIMER)
+#endif
+
#ifdef CONFIG_SMP
/*
* Some systems share FTLB RAMs between threads within a core (siblings in
diff --git a/arch/mips/include/asm/cpu.h b/arch/mips/include/asm/cpu.h
index 388a82f28a87..854e1b44254b 100644
--- a/arch/mips/include/asm/cpu.h
+++ b/arch/mips/include/asm/cpu.h
@@ -429,6 +429,7 @@ enum cpu_type_enum {
#define MIPS_CPU_MAC_2008_ONLY BIT_ULL(60) /* CPU Only support MAC2008 Fused multiply-add instruction */
#define MIPS_CPU_FTLBPAREX BIT_ULL(61) /* CPU has FTLB parity exception */
#define MIPS_CPU_GSEXCEX BIT_ULL(62) /* CPU has GSExc exception */
+#define MIPS_CPU_EXTIMER BIT_ULL(63) /* CPU has External Timer (Loongson) */

/*
* CPU ASE encodings
diff --git a/arch/mips/kernel/cevt-r4k.c b/arch/mips/kernel/cevt-r4k.c
index 995ad9e69ded..fae49e9215b4 100644
--- a/arch/mips/kernel/cevt-r4k.c
+++ b/arch/mips/kernel/cevt-r4k.c
@@ -15,6 +15,8 @@

#include <asm/time.h>
#include <asm/cevt-r4k.h>
+#include <asm/cpu-features.h>
+#include <asm/mipsregs.h>

static int mips_next_event(unsigned long delta,
struct clock_event_device *evt)
@@ -294,6 +296,24 @@ core_initcall(r4k_register_cpufreq_notifier);

#endif /* !CONFIG_CPU_FREQ */

+#ifdef CONFIG_CPU_LOONGSON64
+static int c0_compare_int_enable(struct clock_event_device *cd)
+{
+ if (cpu_has_extimer)
+ set_c0_config6(LOONGSON_CONF6_INTIMER);
+
+ return 0;
+}
+
+static int c0_compare_int_disable(struct clock_event_device *cd)
+{
+ if (cpu_has_extimer)
+ clear_c0_config6(LOONGSON_CONF6_INTIMER);
+
+ return 0;
+}
+#endif

static int __maybe_unused c0_compare_int_enable(...)
{
...
}

without the #ifdef.

Or better, move these two to loongson64 board code, with "extern int c0_compare_int_enable" in a header somewhere.

+
int r4k_clockevent_init(void)
{
unsigned long flags = IRQF_PERCPU | IRQF_TIMER | IRQF_SHARED;
@@ -329,6 +349,11 @@ int r4k_clockevent_init(void)
cd->set_next_event = mips_next_event;
cd->event_handler = mips_event_handler;

+#ifdef CONFIG_CPU_LOONGSON64
+ cd->set_state_oneshot = c0_compare_int_enable;
+ cd->set_state_shutdown = c0_compare_int_disable;
+#endif
+

if (IS_ENABLED(CONFIG_CPU_LOONGSON64)) {
cd->set_state_oneshot = ...;
}

Although I think this is still incorrect: here you check whether the kernel supports this CPU, instead of checking what CPU you're running on.

Cheers,
-Paul

clockevents_config_and_register(cd, mips_hpt_frequency, min_delta, 0x7fffffff);

if (cp0_timer_irq_installed)
diff --git a/arch/mips/kernel/cpu-probe.c b/arch/mips/kernel/cpu-probe.c
index 6be23f205e74..4f1e9ef2644e 100644
--- a/arch/mips/kernel/cpu-probe.c
+++ b/arch/mips/kernel/cpu-probe.c
@@ -2030,6 +2030,9 @@ static inline void decode_cpucfg(struct cpuinfo_mips *c)
if (cfg2 & LOONGSON_CFG2_LEXT2)
c->ases |= MIPS_ASE_LOONGSON_EXT2;

+ if (cfg2 & LOONGSON_CFG2_LLFTP)
+ c->options |= MIPS_CPU_EXTIMER;
+
if (cfg2 & LOONGSON_CFG2_LSPW) {
c->options |= MIPS_CPU_LDPTE;
c->guest.options |= MIPS_CPU_LDPTE;
@@ -2088,7 +2091,8 @@ static inline void cpu_probe_loongson(struct cpuinfo_mips *c, unsigned int cpu)
* Also some early Loongson-3A2000 had wrong TLB type in Config
* register, we correct it here.
*/
- c->options |= MIPS_CPU_FTLB | MIPS_CPU_TLBINV | MIPS_CPU_LDPTE;
+ c->options |= MIPS_CPU_FTLB | MIPS_CPU_TLBINV | MIPS_CPU_LDPTE |
+ MIPS_CPU_EXTIMER;
c->writecombine = _CACHE_UNCACHED_ACCELERATED;
c->ases |= (MIPS_ASE_LOONGSON_MMI | MIPS_ASE_LOONGSON_CAM |
MIPS_ASE_LOONGSON_EXT | MIPS_ASE_LOONGSON_EXT2);
--
2.28.0