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From: tip-bot for Mark Kelly on 3 Aug 2010 14:00
Commit-ID: 0f51a315a1d9018fc70d4aa8a037c690cd87e907
Gitweb: http://git.kernel.org/tip/0f51a315a1d9018fc70d4aa8a037c690cd87e907
Author: Mark Kelly <mark(a)bifferos.com>
AuthorDate: Tue, 3 Aug 2010 18:15:09 +0200
Committer: H. Peter Anvin <hpa(a)linux.intel.com>
CommitDate: Tue, 3 Aug 2010 10:05:25 -0700

x86, cpu: CPU detection for RDC System-on-Chip

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 <mark(a)bifferos.com>
LKML-Reference: <201008031815.09764.florian(a)openwrt.org>
Signed-off-by: Florian Fainelli <florian(a)openwrt.org>
Signed-off-by: H. Peter Anvin <hpa(a)linux.intel.com>
---
Documentation/x86/rdc.txt | 66 ++++++++++++++++++++++++++++++++++
arch/x86/Kconfig | 1 +
arch/x86/include/asm/processor.h | 3 +-
arch/x86/kernel/cpu/Makefile | 1 +
arch/x86/kernel/cpu/rdc.c | 73 ++++++++++++++++++++++++++++++++++++++
5 files changed, 143 insertions(+), 1 deletions(-)

diff --git a/Documentation/x86/rdc.txt b/Documentation/x86/rdc.txt
new file mode 100644
index 0000000..bef506e
--- /dev/null
+++ b/Documentation/x86/rdc.txt
@@ -0,0 +1,66 @@
+
+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(a)bifferos.com 2009
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index dcb0593..6cead94 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -421,6 +421,7 @@ 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 325b7bd..ef43b49 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 5e3a351..04c4749 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(a)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);
--
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