LoongArch: Rework CPU feature probe from CPUCFG/IOCSR

Probe ISA level, TLB, IOCSR information from CPUCFG to improve kernel
resilience to different core implementations.

BTW, IOCSR register definition appears to be a platform-specific spec
instead of an architecture spec, even for the 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>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

1 files changed, 72 insertions, 48 deletions

diff --git a/arch/loongarch/kernel/cpu-probe.c b/arch/loongarch/kernel/cpu-probe.c
index 14f0449f5452..cbce099037b2 100644
--- a/arch/loongarch/kernel/cpu-probe.c
+++ b/arch/loongarch/kernel/cpu-probe.c
@@ -91,12 +91,30 @@ static void cpu_probe_common(struct cpuinfo_loongarch *c)
 	unsigned int config;
 	unsigned long asid_mask;
 
-	c->options = LOONGARCH_CPU_CPUCFG | LOONGARCH_CPU_CSR |
-		     LOONGARCH_CPU_TLB | LOONGARCH_CPU_VINT | LOONGARCH_CPU_WATCH;
+	c->options = LOONGARCH_CPU_CPUCFG | LOONGARCH_CPU_CSR | LOONGARCH_CPU_VINT;
 
 	elf_hwcap = HWCAP_LOONGARCH_CPUCFG;
 
 	config = read_cpucfg(LOONGARCH_CPUCFG1);
+
+	switch (config & CPUCFG1_ISA) {
+	case 0:
+		set_isa(c, LOONGARCH_CPU_ISA_LA32R);
+		break;
+	case 1:
+		set_isa(c, LOONGARCH_CPU_ISA_LA32S);
+		break;
+	case 2:
+		set_isa(c, LOONGARCH_CPU_ISA_LA64);
+		break;
+	default:
+		pr_warn("Warning: unknown ISA level\n");
+	}
+
+	if (config & CPUCFG1_PAGING)
+		c->options |= LOONGARCH_CPU_TLB;
+	if (config & CPUCFG1_IOCSR)
+		c->options |= LOONGARCH_CPU_IOCSR;
 	if (config & CPUCFG1_UAL) {
 		c->options |= LOONGARCH_CPU_UAL;
 		elf_hwcap |= HWCAP_LOONGARCH_UAL;
@@ -139,6 +157,10 @@ static void cpu_probe_common(struct cpuinfo_loongarch *c)
 		c->options |= LOONGARCH_CPU_PTW;
 		elf_hwcap |= HWCAP_LOONGARCH_PTW;
 	}
+	if (config & CPUCFG2_LSPW) {
+		c->options |= LOONGARCH_CPU_LSPW;
+		elf_hwcap |= HWCAP_LOONGARCH_LSPW;
+	}
 	if (config & CPUCFG2_LVZP) {
 		c->options |= LOONGARCH_CPU_LVZ;
 		elf_hwcap |= HWCAP_LOONGARCH_LVZ;
@@ -162,22 +184,6 @@ 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);
@@ -210,6 +216,9 @@ static void cpu_probe_common(struct cpuinfo_loongarch *c)
 	default:
 		pr_warn("Warning: unknown TLB type\n");
 	}
+
+	if (get_num_brps() + get_num_wrps())
+		c->options |= LOONGARCH_CPU_WATCH;
 }
 
 #define MAX_NAME_LEN	32
@@ -220,52 +229,67 @@ static char cpu_full_name[MAX_NAME_LEN] = "        -        ";
 
 static inline void cpu_probe_loongson(struct cpuinfo_loongarch *c, unsigned int cpu)
 {
+	uint32_t config;
 	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:
+	switch (BIT(fls(c->isa_level) - 1)) {
+	case LOONGARCH_CPU_ISA_LA32R:
+	case LOONGARCH_CPU_ISA_LA32S:
 		c->cputype = CPU_LOONGSON32;
-		set_isa(c, LOONGARCH_CPU_ISA_LA32S);
 		__cpu_family[cpu] = "Loongson-32bit";
-		pr_info("32-bit Loongson Processor probed (LA132 Core)\n");
 		break;
-	case PRID_SERIES_LA264:
+	case LOONGARCH_CPU_ISA_LA64:
 		c->cputype = CPU_LOONGSON64;
-		set_isa(c, LOONGARCH_CPU_ISA_LA64);
 		__cpu_family[cpu] = "Loongson-64bit";
-		pr_info("64-bit Loongson Processor probed (LA264 Core)\n");
+		break;
+	}
+
+	switch (c->processor_id & PRID_SERIES_MASK) {
+	case PRID_SERIES_LA132:
+		core_name = "LA132";
+		break;
+	case PRID_SERIES_LA264:
+		core_name = "LA264";
 		break;
 	case PRID_SERIES_LA364:
-		c->cputype = CPU_LOONGSON64;
-		set_isa(c, LOONGARCH_CPU_ISA_LA64);
-		__cpu_family[cpu] = "Loongson-64bit";
-		pr_info("64-bit Loongson Processor probed (LA364 Core)\n");
+		core_name = "LA364";
 		break;
 	case PRID_SERIES_LA464:
-		c->cputype = CPU_LOONGSON64;
-		set_isa(c, LOONGARCH_CPU_ISA_LA64);
-		__cpu_family[cpu] = "Loongson-64bit";
-		pr_info("64-bit Loongson Processor probed (LA464 Core)\n");
+		core_name = "LA464";
 		break;
 	case PRID_SERIES_LA664:
-		c->cputype = CPU_LOONGSON64;
-		set_isa(c, LOONGARCH_CPU_ISA_LA64);
-		__cpu_family[cpu] = "Loongson-64bit";
-		pr_info("64-bit Loongson Processor probed (LA664 Core)\n");
+		core_name = "LA664";
 		break;
-	default: /* Default to 64 bit */
-		c->cputype = CPU_LOONGSON64;
-		set_isa(c, LOONGARCH_CPU_ISA_LA64);
-		__cpu_family[cpu] = "Loongson-64bit";
-		pr_info("64-bit Loongson Processor probed (Unknown Core)\n");
 	}
+
+	pr_info("%s Processor probed (%s Core)\n", __cpu_family[cpu], core_name);
+
+	if (!cpu_has_iocsr)
+		return;
+
+	if (!__cpu_full_name[cpu])
+		__cpu_full_name[cpu] = cpu_full_name;
+
+	*vendor = iocsr_read64(LOONGARCH_IOCSR_VENDOR);
+	*cpuname = iocsr_read64(LOONGARCH_IOCSR_CPUNAME);
+
+	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