[PATCH 3/5] LoongArch: cpu-probe: Move IOCSR probing out of cpu_probe_common

[Jiaxun Yang <jiaxun.yang@flygoat.com>]

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@flygoat.com>
---
 arch/loongarch/kernel/cpu-probe.c | 63 ++++++++++++++++++++++++---------------
 1 file changed, 39 insertions(+), 24 deletions(-)

diff --git a/arch/loongarch/kernel/cpu-probe.c b/arch/loongarch/kernel/cpu-probe.c
index 6a82ceb6e321..968b5a35a0d2 100644
--- a/arch/loongarch/kernel/cpu-probe.c
+++ b/arch/loongarch/kernel/cpu-probe.c
@@ -173,22 +173,6 @@ 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);
@@ -231,16 +215,8 @@ static char cpu_full_name[MAX_NAME_LEN] = "        -        ";
 
 static inline void cpu_probe_loongson(struct cpuinfo_loongarch *c, unsigned int cpu)
 {
-	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 (c->processor_id & PRID_SERIES_MASK) {
 	case PRID_SERIES_LA132:
 		c->cputype = CPU_LOONGSON32;
@@ -283,6 +259,36 @@ 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);
 }
 
+static inline void iocsr_probe_loongson(struct cpuinfo_loongarch *c, unsigned int cpu)
+{
+	uint64_t *vendor = (void *)(&cpu_full_name[VENDOR_OFFSET]);
+	uint64_t *cpuname = (void *)(&cpu_full_name[CPUNAME_OFFSET]);
+	unsigned int config;
+
+	*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
 /* For use by uaccess.h */
 u64 __ua_limit;
@@ -331,6 +337,15 @@ void cpu_probe(void)
 		break;
 	}
 
+	if (c->options & LOONGARCH_CPU_IOCSR) {
+		switch (c->cputype) {
+		case CPU_LOONGSON32:
+		case CPU_LOONGSON64:
+			iocsr_probe_loongson(c, cpu);
+			break;
+		}
+	}
+
 	BUG_ON(!__cpu_family[cpu]);
 	BUG_ON(c->cputype == CPU_UNKNOWN);
 

-- 
2.46.0