MIPS: microMIPS: Add configuration option for microMIPS kernel.

This adds the option to build the Linux kernel using only the
microMIPS ISA. The resulting kernel binary is, at a minimum,
20% smaller than using the MIPS32R2 ISA.
Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com>

arch/mips/Kconfig

@@ -2041,6 +2041,13 @@ config CPU_HAS_SMARTMIPS
 	  you don't know you probably don't have SmartMIPS and should say N
 	  here.
 
+config CPU_MICROMIPS
+	depends on SYS_SUPPORTS_MICROMIPS
+	bool "Build kernel using microMIPS ISA"
+	help
+	  When this option is enabled the kernel will be built using the
+	  microMIPS ISA
+
 config CPU_HAS_WB
 	bool
 

arch/mips/Makefile

@@ -114,6 +114,7 @@ cflags-$(CONFIG_CPU_BIG_ENDIAN)		+= $(shell $(CC) -dumpmachine |grep -q 'mips.*e
 cflags-$(CONFIG_CPU_LITTLE_ENDIAN)	+= $(shell $(CC) -dumpmachine |grep -q 'mips.*el-.*' || echo -EL $(undef-all) $(predef-le))
 
 cflags-$(CONFIG_CPU_HAS_SMARTMIPS)	+= $(call cc-option,-msmartmips)
+cflags-$(CONFIG_CPU_MICROMIPS) += $(call cc-option,-mmicromips -mno-jals)
 
 cflags-$(CONFIG_SB1XXX_CORELIS)	+= $(call cc-option,-mno-sched-prolog) \
 				   -fno-omit-frame-pointer

arch/mips/configs/sead3_defconfig

@@ -2,7 +2,6 @@ CONFIG_MIPS_SEAD3=y
 CONFIG_CPU_LITTLE_ENDIAN=y
 CONFIG_CPU_MIPS32_R2=y
 CONFIG_HZ_100=y
-CONFIG_EXPERIMENTAL=y
 CONFIG_SYSVIPC=y
 CONFIG_POSIX_MQUEUE=y
 CONFIG_NO_HZ=y
@@ -115,10 +114,8 @@ CONFIG_NLS_ISO8859_1=y
 CONFIG_NLS_ISO8859_15=y
 CONFIG_NLS_UTF8=y
 # CONFIG_FTRACE is not set
-CONFIG_CRYPTO=y
 CONFIG_CRYPTO_CBC=y
 CONFIG_CRYPTO_ECB=y
-CONFIG_CRYPTO_AES=y
 CONFIG_CRYPTO_ARC4=y
 # CONFIG_CRYPTO_ANSI_CPRNG is not set
 # CONFIG_CRYPTO_HW is not set

arch/mips/configs/sead3micro_defconfig

+CONFIG_MIPS_SEAD3=y
+CONFIG_CPU_LITTLE_ENDIAN=y
+CONFIG_CPU_MIPS32_R2=y
+CONFIG_CPU_MICROMIPS=y
+CONFIG_HZ_100=y
+CONFIG_SYSVIPC=y
+CONFIG_POSIX_MQUEUE=y
+CONFIG_NO_HZ=y
+CONFIG_HIGH_RES_TIMERS=y
+CONFIG_IKCONFIG=y
+CONFIG_IKCONFIG_PROC=y
+CONFIG_LOG_BUF_SHIFT=15
+CONFIG_EMBEDDED=y
+CONFIG_SLAB=y
+CONFIG_PROFILING=y
+CONFIG_OPROFILE=y
+CONFIG_MODULES=y
+# CONFIG_BLK_DEV_BSG is not set
+# CONFIG_CORE_DUMP_DEFAULT_ELF_HEADERS is not set
+CONFIG_NET=y
+CONFIG_PACKET=y
+CONFIG_UNIX=y
+CONFIG_INET=y
+CONFIG_IP_PNP=y
+CONFIG_IP_PNP_DHCP=y
+CONFIG_IP_PNP_BOOTP=y
+# CONFIG_INET_XFRM_MODE_TRANSPORT is not set
+# CONFIG_INET_XFRM_MODE_TUNNEL is not set
+# CONFIG_INET_XFRM_MODE_BEET is not set
+# CONFIG_INET_LRO is not set
+# CONFIG_INET_DIAG is not set
+# CONFIG_IPV6 is not set
+# CONFIG_WIRELESS is not set
+CONFIG_UEVENT_HELPER_PATH="/sbin/hotplug"
+CONFIG_MTD=y
+CONFIG_MTD_CHAR=y
+CONFIG_MTD_BLOCK=y
+CONFIG_MTD_CFI=y
+CONFIG_MTD_CFI_INTELEXT=y
+CONFIG_MTD_PHYSMAP=y
+CONFIG_MTD_UBI=y
+CONFIG_MTD_UBI_GLUEBI=y
+CONFIG_BLK_DEV_LOOP=y
+CONFIG_BLK_DEV_CRYPTOLOOP=m
+CONFIG_SCSI=y
+# CONFIG_SCSI_PROC_FS is not set
+CONFIG_BLK_DEV_SD=y
+CONFIG_CHR_DEV_SG=y
+# CONFIG_SCSI_LOWLEVEL is not set
+CONFIG_NETDEVICES=y
+CONFIG_SMSC911X=y
+# CONFIG_NET_VENDOR_WIZNET is not set
+CONFIG_MARVELL_PHY=y
+CONFIG_DAVICOM_PHY=y
+CONFIG_QSEMI_PHY=y
+CONFIG_LXT_PHY=y
+CONFIG_CICADA_PHY=y
+CONFIG_VITESSE_PHY=y
+CONFIG_SMSC_PHY=y
+CONFIG_BROADCOM_PHY=y
+CONFIG_ICPLUS_PHY=y
+# CONFIG_WLAN is not set
+# CONFIG_INPUT_MOUSEDEV is not set
+# CONFIG_INPUT_KEYBOARD is not set
+# CONFIG_INPUT_MOUSE is not set
+# CONFIG_SERIO is not set
+# CONFIG_CONSOLE_TRANSLATIONS is not set
+CONFIG_VT_HW_CONSOLE_BINDING=y
+CONFIG_LEGACY_PTY_COUNT=32
+CONFIG_SERIAL_8250=y
+CONFIG_SERIAL_8250_CONSOLE=y
+CONFIG_SERIAL_8250_NR_UARTS=2
+CONFIG_SERIAL_8250_RUNTIME_UARTS=2
+# CONFIG_HW_RANDOM is not set
+CONFIG_I2C=y
+# CONFIG_I2C_COMPAT is not set
+CONFIG_I2C_CHARDEV=y
+# CONFIG_I2C_HELPER_AUTO is not set
+CONFIG_SPI=y
+CONFIG_SENSORS_ADT7475=y
+CONFIG_BACKLIGHT_LCD_SUPPORT=y
+CONFIG_LCD_CLASS_DEVICE=y
+CONFIG_BACKLIGHT_CLASS_DEVICE=y
+# CONFIG_VGA_CONSOLE is not set
+CONFIG_USB=y
+CONFIG_USB_ANNOUNCE_NEW_DEVICES=y
+CONFIG_USB_EHCI_HCD=y
+CONFIG_USB_EHCI_ROOT_HUB_TT=y
+CONFIG_USB_STORAGE=y
+CONFIG_MMC=y
+CONFIG_MMC_DEBUG=y
+CONFIG_MMC_SPI=y
+CONFIG_NEW_LEDS=y
+CONFIG_LEDS_CLASS=y
+CONFIG_LEDS_TRIGGERS=y
+CONFIG_LEDS_TRIGGER_HEARTBEAT=y
+CONFIG_RTC_CLASS=y
+CONFIG_RTC_DRV_M41T80=y
+CONFIG_EXT3_FS=y
+# CONFIG_EXT3_DEFAULTS_TO_ORDERED is not set
+CONFIG_XFS_FS=y
+CONFIG_XFS_QUOTA=y
+CONFIG_XFS_POSIX_ACL=y
+CONFIG_QUOTA=y
+# CONFIG_PRINT_QUOTA_WARNING is not set
+CONFIG_MSDOS_FS=m
+CONFIG_VFAT_FS=m
+CONFIG_TMPFS=y
+CONFIG_JFFS2_FS=y
+CONFIG_NFS_FS=y
+CONFIG_ROOT_NFS=y
+CONFIG_NLS_CODEPAGE_437=y
+CONFIG_NLS_ASCII=y
+CONFIG_NLS_ISO8859_1=y
+CONFIG_NLS_ISO8859_15=y
+CONFIG_NLS_UTF8=y
+# CONFIG_FTRACE is not set
+CONFIG_CRYPTO_CBC=y
+CONFIG_CRYPTO_ECB=y
+CONFIG_CRYPTO_ARC4=y
+# CONFIG_CRYPTO_ANSI_CPRNG is not set
+# CONFIG_CRYPTO_HW is not set

arch/mips/kernel/proc.c

@@ -99,6 +99,10 @@ static int show_cpuinfo(struct seq_file *m, void *v)
 	if (cpu_has_vz)		seq_printf(m, "%s", " vz");
 	seq_printf(m, "\n");
 
+	if (cpu_has_mmips) {
+		seq_printf(m, "micromips kernel\t: %s\n",
+		      (read_c0_config3() & MIPS_CONF3_ISA_OE) ?  "yes" : "no");
+	}
 	seq_printf(m, "shadow register sets\t: %d\n",
 		      cpu_data[n].srsets);
 	seq_printf(m, "kscratch registers\t: %d\n",