x86: CPU id detection for RDC System-on-Chip
Subsystems (2)
PATCH v3 1/1 x86: CPU id detection for RDC System-on-Chip
From: Mark Kelly <[email protected]>
The RDC System-on-Chip i486 compatible core does not support the cpuid instruction and specific detection logic is required for this chip. The patch below adds proper vendor and SoC type detection.
Signed-off-by Mark Kelly <[email protected]>
Tested-by Florian Fainelli <[email protected]>
---
Documentation/x86/rdc.txt new file +67 -0
@@ -0,0 +1,67 @@ + +Introduction +============ + +RDC (http://www.rdc.com.tw) have been manufacturing x86-compatible SoC +(system-on-chips) for a number of years. They are not the fastest of +CPUs (clock speeds ranging from 133-150MHz) but 486SX compatibility +coupled with very low power consumption[1] and low cost make them ideal +for embedded applications. + + +Where to find +============= + +RDC chips show up in numerous embedded devices, but be careful since +many of them will not run Linux 2.6 without significant expertise. + +There are several variants of what the linux kernel refers to generically +as RDC321X: R8610, R321x, S3282 and AMRISC20000. + +R321x: Found in various routers, see the OpenWrt project for details, + http://wiki.openwrt.org/oldwiki/rdcport + +R8610: Found on the RDC evaluation board + http://www.ivankuten.com/system-on-chip-soc/rdc-r8610/ + +AMRISC20000: Found in the MGB-100 wireless hard disk + http://tintuc.no-ip.com/linux/tipps/mgb100/ + +S3282: Found in various NAS devices, including the Bifferboard + http://www.bifferos.com + + +Kernel Configuration +==================== + +Add support for this CPU with CONFIG_X86_RDC321X. Ensure that maths +emulation is included (CONFIG_MATH_EMULATION selected) and avoid MCE +(CONFIG_X86_MCE not selected). + + +CPU detection +============= + +None of these chips support the cpuid instruction, so as with some +other x86 compatible SoCs, we must check the north bridge and look +for specific 'signature' PCI device config. + +If you run a kernel on an unsupported customer id device, please file +a bug with your customer id to: http://bugzilla.kernel.org/. + +Credits +======= + +Many thanks to RDC for providing the customer codes to allow +detection of all known variants, without which this detection code +would have been very hard to ascertain. + + +References +========== + +[1] S3282 in certain NAS solutions consumes less than 1W + + [email protected] 2009 +
arch/x86/Kconfig +1 -0
@@ -422,6 +422,7 @@ config X86_RDC321X bool "RDC R-321x SoC" depends on X86_32 depends on X86_EXTENDED_PLATFORM + select PCI select M486 select X86_REBOOTFIXUPS ---help---
arch/x86/include/asm/processor.h +2 -1
@@ -122,7 +122,8 @@ struct cpuinfo_x86 {#define X86_VENDOR_CENTAUR 5#define X86_VENDOR_TRANSMETA 7#define X86_VENDOR_NSC 8 -#define X86_VENDOR_NUM 9 +#define X86_VENDOR_RDC 9 +#define X86_VENDOR_NUM 10#define X86_VENDOR_UNKNOWN 0xff
arch/x86/kernel/cpu/Makefile +1 -0
@@ -25,6 +25,7 @@ obj-$(CONFIG_CPU_SUP_CYRIX_32) += cyrix.o obj-$(CONFIG_CPU_SUP_CENTAUR) += centaur.o obj-$(CONFIG_CPU_SUP_TRANSMETA_32) += transmeta.o obj-$(CONFIG_CPU_SUP_UMC_32) += umc.o +obj-$(CONFIG_X86_RDC321X) += rdc.o obj-$(CONFIG_PERF_EVENTS) += perf_event.o
arch/x86/kernel/cpu/rdc.c new file +73 -0
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