Date:	Sun, 16 Aug 2009 03:20:40 +0100 (BST)
From:	Mark Kelly <mark@...feros.com>
To:	Ingo Molnar <mingo@...e.hu>
cc:	linux-kernel@...r.kernel.org, "H. Peter Anvin" <hpa@...or.com>,
	Florian Fainelli <florian@...nwrt.org>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [patch] x86 CPU detection for RDC


> ok, this definitely looks like a step in the right direction. The
> patch needs a few small fixes:

Sorry about that - try this one instead:

Signed-off-by: Mark Kelly <mark@...feros.com>
diff --git a/Documentation/x86/rdc.txt b/Documentation/x86/rdc.txt
new file mode 100644
index 0000000..f9591af
--- /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@...oo.co.uk.
+
+
+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@...feros.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..6b02166
--- /dev/null
+++ b/arch/x86/kernel/cpu/rdc.c
@@ -0,0 +1,74 @@
+/*
+   See Documentation/x86/rdc.txt
+
+   mark@...feros.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;
+	u32 customer_id;
+
+	/* 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);
+
+	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 */
+
+	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@...oo.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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