Messages in this thread Patch in this message | | | Date | Sun, 16 Aug 2009 16:46:30 +0100 | Subject | [patch] x86 CPU detection for RDC | From | Mark Kelly <> |
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From about 2.6.29, CPU detection appears to have changed such that a patch is required for RDC x86-compatible CPUs (possibly other undetected x86 CPUs as well). A work-around was to add a couple of null checks to arch/x86/kernel/cpu/common.c, e.g.:
if (this_cpu && this_cpu->c_identify) ~~~~~~~~~~~~~~~~~~~~~~~ this_cpu->c_identify(c);
However the patch below attempts to do this detection properly, and also detect all variants of RDC CPUs. I have also added some documentation for this platform.
See also: http://sites.google.com/site/bifferboard/Home/s3282-kernel-issues
kind regards, Mark.
Signed-off-by: Mark Kelly <mark@bifferos.com>
diff --git a/Documentation/x86/rdc.txt b/Documentation/x86/rdc.txt new file mode 100644 index 0000000..9c6baaa --- /dev/null +++ b/Documentation/x86/rdc.txt @@ -0,0 +1,69 @@ + +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. + +The current detection code has been tested only on the Bifferboard +(S3282 CPU), please send bug reports or success stories with +other devices to bifferos@yahoo.co.uk. + + +Refs +==== + +[1] S3282 in certain NAS solutions consumes less than 1W + + +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. + + +mark@bifferos.com 2009 + diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index c2cceae..6f9f853 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -121,7 +121,8 @@ 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 diff --git a/arch/x86/kernel/cpu/Makefile b/arch/x86/kernel/cpu/Makefile index 4e242f9..9906064 100644 --- a/arch/x86/kernel/cpu/Makefile +++ b/arch/x86/kernel/cpu/Makefile @@ -22,6 +22,7 @@ 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_X86_MCE) += mcheck/ obj-$(CONFIG_MTRR) += mtrr/ diff --git a/arch/x86/kernel/cpu/rdc.c b/arch/x86/kernel/cpu/rdc.c new file mode 100644 index 0000000..5a6aea7 --- /dev/null +++ b/arch/x86/kernel/cpu/rdc.c @@ -0,0 +1,72 @@ +/* + See Documentation/x86/rdc.txt + + mark@bifferos.com +*/ + +#include <linux/pci.h> +#include <asm/pci-direct.h> +#include "cpu.h" + + +static void __cpuinit rdc_identify(struct cpuinfo_x86 *c) +{ + u16 vendor, device; + + /* RDC CPU is SoC (system-on-chip), Northbridge is always present. */ + vendor = read_pci_config_16(0, 0, 0, PCI_VENDOR_ID); + device = read_pci_config_16(0, 0, 0, PCI_DEVICE_ID); + + /* We could go on and check other devices, e.g. r6040 NIC, but that's probably overkill */ + if (vendor == PCI_VENDOR_ID_RDC && device == PCI_DEVICE_ID_RDC_R6020) + { + u32 customer_id; + + strcpy(c->x86_vendor_id, "RDC"); + c->x86_vendor = X86_VENDOR_RDC; + + customer_id = read_pci_config(0, 0, 0, 0x90); + + switch (customer_id) + { + // id names are from RDC. + case 0x00321000 : + strcpy(c->x86_model_id, "R3210/R3211"); + break; + case 0x00321001 : + strcpy(c->x86_model_id, "AMITRISC20000/20010"); + break; + case 0x00321002 : + strcpy(c->x86_model_id, "R3210X/Edimax"); + break; + case 0x00321003 : + strcpy(c->x86_model_id, "R3210/Kcodes"); + break; + case 0x00321004 : // tested + strcpy(c->x86_model_id, "S3282/CodeTek"); + break; + case 0x00321007 : + strcpy(c->x86_model_id, "R8610"); + break; + default : + printk(KERN_INFO "Unrecognised Customer ID (0x%x) please report to bifferos@yahoo.co.uk\n", customer_id); + + /* We'll default to the R321x since that's mentioned elsewhere in the + kernel sources. */ + strcpy(c->x86_model_id, "R321x"); + + /* blank the vendor_id, so we get a warning that this is unsupported, your + system may be unstable etc... Is there a better way? */ + strcpy(c->x86_vendor_id, ""); + } + } +} + +static const struct cpu_dev __cpuinitconst rdc_cpu_dev = { + .c_vendor = "RDC", + .c_ident = { "RDC" }, + .c_identify = rdc_identify, + .c_x86_vendor = X86_VENDOR_RDC, +}; + +cpu_dev_register(rdc_cpu_dev);
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