Re: [PATCH v3] x86: CPU detection for RDC System-on-Chip

[Florian Fainelli <florian@openwrt.org>]

On Wednesday 19 May 2010 09:27:12 Florian Fainelli wrote:
> From: Mark Kelly <mark@bifferos.com>
> 
> 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.

Is this version acceptable like it is now?

Thank you for your answer.

> 
> Signed-off-by: Mark Kelly <mark@bifferos.com>
> Tested-by: Florian Fainelli <florian@openwrt.org>
> ---
> Changes from v3:
> - read vendor and device id with a single 32-bits read
> 
> Changes from v2:
> - change report url to bugzilla.kernel.org
> - set vendor name to RDC even if customer id is not known
> 
> diff --git a/Documentation/x86/rdc.txt b/Documentation/x86/rdc.txt
> new file mode 100644
> index 0000000..f3dc7cf
> --- /dev/null
> +++ b/Documentation/x86/rdc.txt
> @@ -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
> +
> +
> +mark@bifferos.com 2009
> +
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index 39e8e10..21b02f2 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -419,6 +419,7 @@ 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---
> diff --git a/arch/x86/include/asm/processor.h
> b/arch/x86/include/asm/processor.h index 5a51379..eddf979 100644
> --- a/arch/x86/include/asm/processor.h
> +++ b/arch/x86/include/asm/processor.h
> @@ -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
> 
> diff --git a/arch/x86/kernel/cpu/Makefile b/arch/x86/kernel/cpu/Makefile
> index 3a785da..af2d4a6 100644
> --- a/arch/x86/kernel/cpu/Makefile
> +++ b/arch/x86/kernel/cpu/Makefile
> @@ -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
> 
> diff --git a/arch/x86/kernel/cpu/rdc.c b/arch/x86/kernel/cpu/rdc.c
> new file mode 100644
> index 0000000..c2bcdcc
> --- /dev/null
> +++ b/arch/x86/kernel/cpu/rdc.c
> @@ -0,0 +1,73 @@
> +/*
> + * 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)
> +{
> +	u32 id;
> +	u16 vendor, device;
> +	u32 customer_id;
> +
> +	if (!early_pci_allowed())
> +		return;
> +
> +	/* RDC CPU is SoC (system-on-chip), Northbridge is always present */
> +	id = read_pci_config(0, 0, 0, PCI_VENDOR_ID);
> +	vendor = id & 0xffff;
> +	device = (id >> 16) & 0xffff;
> +
> +	if (vendor != PCI_VENDOR_ID_RDC || device != PCI_DEVICE_ID_RDC_R6020)
> +		return;  /* not RDC */
> +	/*
> +	 * NB: We could go on and check other devices, e.g. r6040 NIC, but
> +	 * that's probably overkill
> +	 */
> +
> +	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:
> +		pr_info("RDC CPU: Unrecognised Customer ID (0x%x) please "
> +			"report to: http://bugzilla.kernel.org/\n",
> +			customer_id);
> +		break;
> +	}
> +
> +	strcpy(c->x86_vendor_id, "RDC");
> +	c->x86_vendor = X86_VENDOR_RDC;
> +}
> +
> +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);