nds32: support hardware prefetcher

We add a config for user to enable or disable this feature.
It can be used to control the hardware prefetch function.
Signed-off-by: Nylon Chen <nylon7@andestech.com>
Acked-by: Greentime Hu <greentime@andestech.com>
Signed-off-by: Greentime Hu <greentime@andestech.com>

arch/nds32/Kconfig.cpu

@@ -177,6 +177,13 @@ config CACHE_L2
 	  Say Y here to enable L2 cache if your SoC are integrated with L2CC.
 	  If unsure, say N.
 
+config HW_PRE
+	bool "Enable hardware prefetcher"
+	default y
+	help
+	  Say Y here to enable hardware prefetcher feature.
+	  Only when CPU_VER.REV >= 0x09 can support.
+
 menu "Memory configuration"
 
 choice

arch/nds32/include/asm/bitfield.h

@@ -740,14 +740,20 @@
 #define N13MISC_CTL_offRTP	1	/* Disable Return Target Predictor */
 #define N13MISC_CTL_offPTEPF	2	/* Disable HPTWK L2 PTE pefetch */
 #define N13MISC_CTL_offSP_SHADOW_EN	4	/* Enable shadow stack pointers */
+#define MISC_CTL_offHWPRE      11      /* Enable HardWare PREFETCH */
 /* bit 6, 9:31 reserved */
 
 #define N13MISC_CTL_makBTB	( 0x1  << N13MISC_CTL_offBTB )
 #define N13MISC_CTL_makRTP	( 0x1  << N13MISC_CTL_offRTP )
 #define N13MISC_CTL_makPTEPF	( 0x1  << N13MISC_CTL_offPTEPF )
 #define N13MISC_CTL_makSP_SHADOW_EN	( 0x1  << N13MISC_CTL_offSP_SHADOW_EN )
+#define MISC_CTL_makHWPRE_EN     ( 0x1  << MISC_CTL_offHWPRE )
 
+#ifdef CONFIG_HW_PRE
+#define MISC_init	(N13MISC_CTL_makBTB|N13MISC_CTL_makRTP|N13MISC_CTL_makSP_SHADOW_EN|MISC_CTL_makHWPRE_EN)
+#else
 #define MISC_init	(N13MISC_CTL_makBTB|N13MISC_CTL_makRTP|N13MISC_CTL_makSP_SHADOW_EN)
+#endif
 
 /******************************************************************************
  * PRUSR_ACC_CTL (Privileged Resource User Access Control Registers)

arch/nds32/kernel/head.S

@@ -151,7 +151,7 @@ _tlb:
 #endif
 	mtsr    $r3, $TLB_MISC
 
-	mfsr    $r0, $MISC_CTL      ! Enable BTB and RTP and shadow sp
+	mfsr    $r0, $MISC_CTL      ! Enable BTB, RTP, shadow sp, and HW_PRE
 	ori     $r0, $r0, #MISC_init
 	mtsr    $r0, $MISC_CTL
 

arch/nds32/kernel/setup.c

@@ -39,6 +39,7 @@
 #define HWCAP_FPU_DP		0x040000
 #define HWCAP_V2		0x080000
 #define HWCAP_DX_REGS		0x100000
+#define HWCAP_HWPRE		0x200000
 
 unsigned long cpu_id, cpu_rev, cpu_cfgid;
 bool has_fpu = false;
@@ -75,6 +76,7 @@ static const char *hwcap_str[] = {
 	"fpu_dp",
 	"v2",
 	"dx_regs",
+	"hw_pre",
 	NULL,
 };
 
@@ -221,6 +223,11 @@ static void __init setup_cpuinfo(void)
 	if (__nds32__mfsr(NDS32_SR_MSC_CFG) & MSC_CFG_mskL2C)
 		elf_hwcap |= HWCAP_L2C;
 
+#ifdef CONFIG_HW_PRE
+	if (__nds32__mfsr(NDS32_SR_MISC_CTL) & MISC_CTL_makHWPRE_EN)
+		elf_hwcap |= HWCAP_HWPRE;
+#endif
+
 	tmp = __nds32__mfsr(NDS32_SR_CACHE_CTL);
 	if (!IS_ENABLED(CONFIG_CPU_DCACHE_DISABLE))
 		tmp |= CACHE_CTL_mskDC_EN;