[PATCH v3 2/4] LoongArch: cpu-probe: Move IOCSR probing out of cpu_probe_common

[Jiaxun Yang <jiaxun.yang@xxxxxxxxxxx>]

IOCSR register definition appears to be a platform specific
spec instead of architecture spec, even for Loongson CPUs
there is no guarantee that IOCSR will always present.

Thus it's dangerous to perform IOCSR probing without checking
CPU type and instruction availability.

Signed-off-by: Jiaxun Yang <jiaxun.yang@xxxxxxxxxxx>
---
 arch/loongarch/kernel/cpu-probe.c | 50 +++++++++++++++++++++------------------
 1 file changed, 27 insertions(+), 23 deletions(-)

diff --git a/arch/loongarch/kernel/cpu-probe.c b/arch/loongarch/kernel/cpu-probe.c
index a5473bb673e5..8a868a10df9c 100644
--- a/arch/loongarch/kernel/cpu-probe.c
+++ b/arch/loongarch/kernel/cpu-probe.c
@@ -182,22 +182,6 @@ static void cpu_probe_common(struct cpuinfo_loongarch *c)
 	if (config & CPUCFG6_PMP)
 		c->options |= LOONGARCH_CPU_PMP;
 
-	config = iocsr_read32(LOONGARCH_IOCSR_FEATURES);
-	if (config & IOCSRF_CSRIPI)
-		c->options |= LOONGARCH_CPU_CSRIPI;
-	if (config & IOCSRF_EXTIOI)
-		c->options |= LOONGARCH_CPU_EXTIOI;
-	if (config & IOCSRF_FREQSCALE)
-		c->options |= LOONGARCH_CPU_SCALEFREQ;
-	if (config & IOCSRF_FLATMODE)
-		c->options |= LOONGARCH_CPU_FLATMODE;
-	if (config & IOCSRF_EIODECODE)
-		c->options |= LOONGARCH_CPU_EIODECODE;
-	if (config & IOCSRF_AVEC)
-		c->options |= LOONGARCH_CPU_AVECINT;
-	if (config & IOCSRF_VM)
-		c->options |= LOONGARCH_CPU_HYPERVISOR;
-
 	config = csr_read32(LOONGARCH_CSR_ASID);
 	config = (config & CSR_ASID_BIT) >> CSR_ASID_BIT_SHIFT;
 	asid_mask = GENMASK(config - 1, 0);
@@ -240,15 +224,10 @@ static char cpu_full_name[MAX_NAME_LEN] = "        -        ";
 
 static inline void cpu_probe_loongson(struct cpuinfo_loongarch *c, unsigned int cpu)
 {
+	uint32_t config;
+	const char *core_name = "Unknown";
 	uint64_t *vendor = (void *)(&cpu_full_name[VENDOR_OFFSET]);
 	uint64_t *cpuname = (void *)(&cpu_full_name[CPUNAME_OFFSET]);
-	const char *core_name = "Unknown";
-
-	if (!__cpu_full_name[cpu])
-		__cpu_full_name[cpu] = cpu_full_name;
-
-	*vendor = iocsr_read64(LOONGARCH_IOCSR_VENDOR);
-	*cpuname = iocsr_read64(LOONGARCH_IOCSR_CPUNAME);
 
 	switch (BIT(fls(c->isa_level) - 1)) {
 	case LOONGARCH_CPU_ISA_LA32R:
@@ -284,6 +263,31 @@ static inline void cpu_probe_loongson(struct cpuinfo_loongarch *c, unsigned int
 	}
 
 	pr_info("%s Processor probed (%s Core)\n", __cpu_family[cpu], core_name);
+
+	if (!(c->options & LOONGARCH_CPU_IOCSR))
+		return;
+
+	*vendor = iocsr_read64(LOONGARCH_IOCSR_VENDOR);
+	*cpuname = iocsr_read64(LOONGARCH_IOCSR_CPUNAME);
+
+	if (!__cpu_full_name[cpu])
+		__cpu_full_name[cpu] = cpu_full_name;
+
+	config = iocsr_read32(LOONGARCH_IOCSR_FEATURES);
+	if (config & IOCSRF_CSRIPI)
+		c->options |= LOONGARCH_CPU_CSRIPI;
+	if (config & IOCSRF_EXTIOI)
+		c->options |= LOONGARCH_CPU_EXTIOI;
+	if (config & IOCSRF_FREQSCALE)
+		c->options |= LOONGARCH_CPU_SCALEFREQ;
+	if (config & IOCSRF_FLATMODE)
+		c->options |= LOONGARCH_CPU_FLATMODE;
+	if (config & IOCSRF_EIODECODE)
+		c->options |= LOONGARCH_CPU_EIODECODE;
+	if (config & IOCSRF_AVEC)
+		c->options |= LOONGARCH_CPU_AVECINT;
+	if (config & IOCSRF_VM)
+		c->options |= LOONGARCH_CPU_HYPERVISOR;
 }
 
 #ifdef CONFIG_64BIT

-- 
2.46.0