On Fri, Nov 30, 2012 at 04:03:38PM +0000, Russell King - ARM Linux wrote:

On Fri, Nov 30, 2012 at 10:41:13AM -0500, Christoffer Dall wrote:

quoted

Decoding the implementor and part number of the CPU id in the CPU ID
register is needed by KVM, so we factor it out to share the code.

Cc: Will Deacon <redacted>
Signed-off-by: Christoffer Dall <redacted>
---
Changes since v2:
 - Take implementor as argument to read_cpuid_part_number

Actually, I don't think this is the correct way.  There's noting
inherently different about Xscale wrt part numbers, it's just that
someone decided to do stuff "differently" and use the CPU part
number to identify the SoC as a whole.

Here's the full list:

80200	69052000	fffffff0
PXA250	69052100	fffff7f0
PXA210	69052120	fffff3f0
8032x	69052420	fffff7e0
PXA255	69052d00	fffffff0
80219	69052e20	ffffffe0
8033x	69054010	fffffd30
IXP43x	69054040	fffffff0
PXA270	69054110	fffffff0
IXP2400	69054190	fffffff0
IXP2800	690541a0	fffffff0
IXP42x	690541c0	ffffffc0
IXP46x	69054200	ffffff00
Xscale3	69056000	ffffe000
PXA935	56056000	ffffe000

What we get from these is:
XScale1 can be identified by (id & 0xe000) == 0x2000
Xscale2 can be identified by (id & 0xe000) == 0x4000
Xscale3 can be identified by (id & 0xe000) == 0x6000

I don't think we should make a distinction in read_cpuid_part_number()
between these; if manufacturers are silly enough to abuse these fields
then its their problem. :)

What I suggest is that read_cpuid_part_number() returns the part number
field as defined by ARM.  We then also define XSCALE_ARCH_MASK to be
0xe000 and a bunch of XSCALE_ARCH_V1..V3 along those lines.  Maybe even
a xscale_cpu_version() macro which returns the XScale CPU version
pre-masked.

Here's the other place where the CPU ID is parsed on Xscale devices:

drivers/usb/gadget/pxa25x_udc.c-#define CP15R0_VENDOR_MASK	0xffffe000
drivers/usb/gadget/pxa25x_udc.c:#define CP15R0_XSCALE_VALUE	0x69052000	/* intel/arm/xscale */
drivers/usb/gadget/pxa25x_udc.c:#define CP15R0_XSCALE_VALUE	0x69054000	/* intel/arm/ixp4xx */
drivers/usb/gadget/pxa25x_udc.c-	asm("mrc%? p15, 0, %0, c0, c0" : "=r" (chiprev));
drivers/usb/gadget/pxa25x_udc.c:	if ((chiprev & CP15R0_VENDOR_MASK) != CP15R0_XSCALE_VALUE) {
drivers/usb/gadget/pxa25x_udc.c-		pr_err("%s: not XScale!\n", driver_name);
drivers/usb/gadget/pxa25x_udc.c-		return -ENODEV;
drivers/usb/gadget/pxa25x_udc.c-	}