nios2: Add CDX support

Add support for the CDX Code Density Extensions present in
Nios II R2 . This introduces new 16bit instruction set to
improve code density while retaining support for the 32bit
Nios II R2 instructions.
Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Ley Foon Tan <lftan@altera.com>

arch/nios2/Makefile

@@ -30,6 +30,7 @@ KBUILD_CFLAGS += $(if $(CONFIG_NIOS2_HW_MUL_SUPPORT),-mhw-mul,-mno-hw-mul)
 KBUILD_CFLAGS += $(if $(CONFIG_NIOS2_HW_MULX_SUPPORT),-mhw-mulx,-mno-hw-mulx)
 KBUILD_CFLAGS += $(if $(CONFIG_NIOS2_HW_DIV_SUPPORT),-mhw-div,-mno-hw-div)
 KBUILD_CFLAGS += $(if $(CONFIG_NIOS2_BMX_SUPPORT),-mbmx,-mno-bmx)
+KBUILD_CFLAGS += $(if $(CONFIG_NIOS2_CDX_SUPPORT),-mcdx,-mno-cdx)
 KBUILD_CFLAGS += $(if $(CONFIG_NIOS2_FPU_SUPPORT),-mcustom-fpu-cfg=60-1,)
 
 KBUILD_CFLAGS += -fno-optimize-sibling-calls

arch/nios2/include/asm/cpuinfo.h

@@ -30,6 +30,7 @@ struct cpuinfo {
 	bool has_mul;
 	bool has_mulx;
 	bool has_bmx;
+	bool has_cdx;
 
 	/* CPU caches */
 	u32 icache_line_size;

arch/nios2/kernel/cpuinfo.c

@@ -68,6 +68,7 @@ void __init setup_cpuinfo(void)
 	cpuinfo.has_mul = of_property_read_bool(cpu, "altr,has-mul");
 	cpuinfo.has_mulx = of_property_read_bool(cpu, "altr,has-mulx");
 	cpuinfo.has_bmx = of_property_read_bool(cpu, "altr,has-bmx");
+	cpuinfo.has_cdx = of_property_read_bool(cpu, "altr,has-cdx");
 	cpuinfo.mmu = of_property_read_bool(cpu, "altr,has-mmu");
 
 	if (IS_ENABLED(CONFIG_NIOS2_HW_DIV_SUPPORT) && !cpuinfo.has_div)
@@ -82,6 +83,9 @@ void __init setup_cpuinfo(void)
 	if (IS_ENABLED(CONFIG_NIOS2_BMX_SUPPORT) && !cpuinfo.has_bmx)
 		err_cpu("BMX");
 
+	if (IS_ENABLED(CONFIG_NIOS2_CDX_SUPPORT) && !cpuinfo.has_cdx)
+		err_cpu("CDX");
+
 	cpuinfo.tlb_num_ways = fcpu(cpu, "altr,tlb-num-ways");
 	if (!cpuinfo.tlb_num_ways)
 		panic("altr,tlb-num-ways can't be 0. Please check your hardware "
@@ -148,11 +152,13 @@ static int show_cpuinfo(struct seq_file *m, void *v)
 		   " MUL:\t\t%s\n"
 		   " MULX:\t\t%s\n"
 		   " DIV:\t\t%s\n"
-		   " BMX:\t\t%s\n",
+		   " BMX:\t\t%s\n"
+		   " CDX:\t\t%s\n",
 		   cpuinfo.has_mul ? "yes" : "no",
 		   cpuinfo.has_mulx ? "yes" : "no",
 		   cpuinfo.has_div ? "yes" : "no",
-		   cpuinfo.has_bmx ? "yes" : "no");
+		   cpuinfo.has_bmx ? "yes" : "no",
+		   cpuinfo.has_cdx ? "yes" : "no");
 
 	seq_printf(m,
 		   "Icache:\t\t%ukB, line length: %u\n",

arch/nios2/platform/Kconfig.platform

@@ -90,6 +90,15 @@ config NIOS2_BMX_SUPPORT
 	  the BMX Bit Manipulation Extension instructions. Enables
 	  the -mbmx compiler flag.
 
+config NIOS2_CDX_SUPPORT
+	bool "Enable CDX instructions"
+	depends on NIOS2_ARCH_REVISION = 2
+	default n
+	help
+	  Set to true if you configured the Nios II R2 to include
+	  the CDX Bit Manipulation Extension instructions. Enables
+	  the -mcdx compiler flag.
+
 config NIOS2_FPU_SUPPORT
 	bool "Custom floating point instr support"
 	default n