CPU Temperature Patch

CPU Temperature Patch

[D.J. Osguthorpe]

Here are two patches that appear to fix the cpu_temp function in setup.c.
They have been applied to a number of Ben Herrenschmidt kernels on a 500 MHz
Pismo powerbook and print reasonable values when you cat /proc/cpuinfo.

Note that the intrinsic resolution of the temperature seems to be 4 degrees
- the values printed are at the mid-point between two 4 degree multiples.

The key document I found for this was a Motorola application note found under

http://www.mot.com/SPS/PowerPC/teksupport/teklibrary/index.html

The specific document is "Programming the Thermal Assist Unit in the MPC750,
Rev.0".

http://www.mot.com/SPS/PowerPC/teksupport/teklibrary/appnotes/an1800.pdf.


The update of processor.h means that everything gets re-compiled after
applying the patch.


David Osguthorpe


--- orig/linux-2.2.17pre13-ben1/include/asm-ppc/processor.h	Sun Jul 23 11:34:51 2000
+++ linux-2.2.17pre13-ben1/include/asm-ppc/processor.h	Mon Aug 14 23:40:36 2000
@@ -163,13 +163,15 @@
 #define THRM1	1020
 #define THRM2	1021
 #define THRM3	1022
-#define THRM1_TIN 0x1
-#define THRM1_TIV 0x2
-#define THRM1_THRES (0x7f<<2)
-#define THRM1_TID (1<<29)
-#define THRM1_TIE (1<<30)
-#define THRM1_V   (1<<31)
-#define THRM3_E   (1<<31)
+/*	these bits were defined in inverted endian sense originally */
+#define THRM1_TIN (1 << 31)
+#define THRM1_TIV (1 << 30)
+#define THRM1_THRES(x) ((x&0x7f)<<23)
+#define THRM3_SITV(x) ((x&0x3fff)<<1)
+#define THRM1_TID (1<<2)
+#define THRM1_TIE (1<<1)
+#define THRM1_V   (1<<0)
+#define THRM3_E   (1<<0)

 /* Segment Registers */
 #define SR0	0


--- orig/linux-2.2.17pre13-ben1/arch/ppc/kernel/setup.c	Fri Jul 14 11:18:18 2000
+++ linux-2.2.17pre13-ben1/arch/ppc/kernel/setup.c	Tue Sep 19 10:16:43 2000
@@ -177,31 +177,69 @@
 }
 #endif

+
+extern int _get_THRM1();
+extern int _get_THRM2();
+extern int _get_THRM3();
+extern int _set_THRM1(int);
+extern int _set_THRM2(int);
+extern int _set_THRM3(int);
+
 unsigned long cpu_temp(void)
 {
 	unsigned char thres = 0;
+	unsigned int othrm1;
+	unsigned int othrm2;
+	unsigned int othrm3;
+	unsigned int thrm1;
+	unsigned int thrm3;
+	unsigned int cnt;
+	unsigned int thresd;
+	unsigned int threst;
+	unsigned int i;

-#if 0
+	othrm1 = _get_THRM1();
+	othrm2 = _get_THRM2();
+	othrm3 = _get_THRM3();
 	/* disable thrm2 */
 	_set_THRM2( 0 );
-	/* threshold 0 C, tid: exceeding threshold, tie: don't generate interrupt */
-	_set_THRM1( THRM1_V );
-
+	_set_THRM1( 0 );
+
 	/* we need 20us to do the compare - assume 300MHz processor clock */
+	/* max value for sitv is 0x3fff - or 16383 */
+	/* this set for 500 MHz Pismo - how do we get access to clock?? */
+	/* 25 usec conversion time - max for 500 Mhz is approx. 32 usec */
 	_set_THRM3(0);
-	_set_THRM3(THRM3_E | (300*30)<<18 );
+	_set_THRM3(THRM3_E | THRM3_SITV(500*25) );

-	udelay(100);
-	/* wait for the compare to complete */
-	/*while ( !(_get_THRM1() & THRM1_TIV) ) ;*/
-	if ( !(_get_THRM1() & THRM1_TIV) )
-		printk("no tiv\n");
-	if ( _get_THRM1() & THRM1_TIN )
-		printk("crossed\n");
+	thresd = 1 << 6;
+	threst = thresd;
+	i =  7;
+	while (i > 1 && thresd > 2)
+		{
+		thrm1 = (THRM1_THRES(threst)) | THRM1_V;
+		_set_THRM1(thrm1);
+		cnt = 10000;
+		while ( !((thrm1=_get_THRM1()) & THRM1_TIV) && cnt ) cnt--;
+		/* printk("THRM1 %8x %d %c %d %d %d\n",thrm1,10000-cnt,(thrm1&THRM1_TIN?'x':' '),threst,thresd,i); */
+		if (cnt == 0)
+			{ printk("THRM1: no interrupt %8x\n",thrm1); threst = 0; break; }
+		else
+			{
+			if ( thrm1 & THRM1_TIN )
+				{ thresd = thresd >> 1; threst += thresd; }
+			else
+				{ thresd = thresd >> 1; threst -= thresd; }
+			i--;
+			}
+		}
+	thres = threst;
+	/* printk("THRM1 %d\n",threst); */
 	/* turn everything off */
-	_set_THRM3(0);
-	_set_THRM1(0);
-#endif
+	_set_THRM3(othrm3);
+	/*_set_THRM1(0);*/
+	_set_THRM1(othrm1);
+	_set_THRM2(othrm2);

 	return thres;
 }

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Re: CPU Temperature Patch

[Albrecht Dre_]

"D.J. Osguthorpe" wrote:
> Here are two patches that appear to fix the cpu_temp function in setup.c.
> They have been applied to a number of Ben Herrenschmidt kernels on a 500 MHz
> Pismo powerbook and print reasonable values when you cat /proc/cpuinfo.

The patch seems to work on my Lombard/333, too... Really great!

> +       /* this set for 500 MHz Pismo - how do we get access to clock?? */

There is, in the same file, around line 319 code to read the clock speed from
the device tree. However, is it really necessary to include the clock speed at
this point? What is the drawback if we just assume 500 MHz (or even the max
value) for every G3 based machine?

Albrecht.


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Re: CPU Temperature Patch

[Tom Rini]

On Wed, Sep 20, 2000 at 05:03:42PM +0200, Albrecht Dreß wrote:
>
> "D.J. Osguthorpe" wrote:
> > Here are two patches that appear to fix the cpu_temp function in setup.c.
> > They have been applied to a number of Ben Herrenschmidt kernels on a 500 MHz
> > Pismo powerbook and print reasonable values when you cat /proc/cpuinfo.
>
> The patch seems to work on my Lombard/333, too... Really great!
>
> > +       /* this set for 500 MHz Pismo - how do we get access to clock?? */
>
> There is, in the same file, around line 319 code to read the clock speed from
> the device tree. However, is it really necessary to include the clock speed at
> this point? What is the drawback if we just assume 500 MHz (or even the max
> value) for every G3 based machine?

Why assume when we can do it properly?  Besides, a friend of mine oc'ed his
B&W to 550, so it's possible to have >500Mhz :)

--
Tom Rini (TR1265)
http://gate.crashing.org/~trini/

** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/

Re: CPU Temperature Patch

[Michael Schmitz]

> > > +       /* this set for 500 MHz Pismo - how do we get access to clock?? */
> >
> > There is, in the same file, around line 319 code to read the clock speed from
> > the device tree. However, is it really necessary to include the clock speed at
> > this point? What is the drawback if we just assume 500 MHz (or even the max
> > value) for every G3 based machine?
>
> Why assume when we can do it properly?  Besides, a friend of mine oc'ed his
> B&W to 550, so it's possible to have >500Mhz :)

Like this?

--- arch/ppc/kernel/setup.c.org	Wed Sep 20 20:25:53 2000
+++ arch/ppc/kernel/setup.c	Wed Sep 20 20:31:26 2000
@@ -197,6 +197,7 @@
 	unsigned int thresd;
 	unsigned int threst;
 	unsigned int i;
+	unsigned int cpu_freq;

 	othrm1 = _get_THRM1();
 	othrm2 = _get_THRM2();
@@ -208,9 +209,23 @@
 	/* we need 20us to do the compare - assume 300MHz processor clock */
 	/* max value for sitv is 0x3fff - or 16383 */
 	/* this set for 500 MHz Pismo - how do we get access to clock?? */
+
+	cpu_freq = 500;
+	if ( have_of )
+	{
+		struct device_node *cpu_node;
+		int *fp;
+
+		cpu_node = find_type_devices("cpu");
+		if ( cpu_node ) {
+			fp = (int *) get_property(cpu_node, "clock-frequency", NULL);
+			if ( fp ) cpu_freq = *fp / 1000000;
+		}
+	}
+
 	/* 25 usec conversion time - max for 500 Mhz is approx. 32 usec */
 	_set_THRM3(0);
-	_set_THRM3(THRM3_E | THRM3_SITV(500*25) );
+	_set_THRM3(THRM3_E | THRM3_SITV(cpu_freq*25) );

 	thresd = 1 << 6;
 	threst = thresd;

Only tested on my Lombard ...

	Michael


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Re: CPU Temperature Patch

[Tom Rini]

On Wed, Sep 20, 2000 at 09:15:27PM +0200, Michael Schmitz wrote:
> > > > +       /* this set for 500 MHz Pismo - how do we get access to clock?? */
> > >
> > > There is, in the same file, around line 319 code to read the clock speed from
> > > the device tree. However, is it really necessary to include the clock speed at
> > > this point? What is the drawback if we just assume 500 MHz (or even the max
> > > value) for every G3 based machine?
> >
> > Why assume when we can do it properly?  Besides, a friend of mine oc'ed his
> > B&W to 550, so it's possible to have >500Mhz :)
>
> Like this?

Looks almost sane.

> @@ -208,9 +209,23 @@
>  	/* we need 20us to do the compare - assume 300MHz processor clock */
>  	/* max value for sitv is 0x3fff - or 16383 */
>  	/* this set for 500 MHz Pismo - how do we get access to clock?? */
> +
> +	cpu_freq = 500;

But why 500 here?  The bit for reading temp is on all G3s, yes?  And since
we assume 300Mhz clock, which is the middle of the clock ranges (close enough)
shouldn't this be 300 as well?

--
Tom Rini (TR1265)
http://gate.crashing.org/~trini/

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Re: CPU Temperature Patch

[Michel Lanners]

Hi all,

On  20 Sep, this message from Tom Rini echoed through cyberspace:
>
> On Wed, Sep 20, 2000 at 05:03:42PM +0200, Albrecht Dreß wrote:
>>
>> "D.J. Osguthorpe" wrote:
>> > Here are two patches that appear to fix the cpu_temp function in setup.c.
>> > They have been applied to a number of Ben Herrenschmidt kernels on a 500 MHz
>> > Pismo powerbook and print reasonable values when you cat /proc/cpuinfo.
>>
>> The patch seems to work on my Lombard/333, too... Really great!
>>
>> > +       /* this set for 500 MHz Pismo - how do we get access to clock?? */
>>
>> There is, in the same file, around line 319 code to read the clock speed from
>> the device tree. However, is it really necessary to include the clock speed at
>> this point? What is the drawback if we just assume 500 MHz (or even the max
>> value) for every G3 based machine?
>
> Why assume when we can do it properly?  Besides, a friend of mine oc'ed his
> B&W to 550, so it's possible to have >500Mhz :)

To do it properly on all machines requires a processor frequency
calculating routine, that doesn't depend on OF. Note that on all
upgraded machines that did not initially have a G3, OF's value is wrong
(too low, actually)!

On the other hand, Motorola's doc states that setting too large a value
doesn't hurt, so I guess we can safely hardcode something like 600 MHz.

At the only expense of busy-waiting a bit too long on slower machines...
but how often do you look at /proc/cpuinfo? Besides, you could always do
the aproximation using the interrupt ;-)

Michel

-------------------------------------------------------------------------
Michel Lanners                 |  " Read Philosophy.  Study Art.
23, Rue Paul Henkes            |    Ask Questions.  Make Mistakes.
L-1710 Luxembourg              |
email   mlan@cpu.lu            |
http://www.cpu.lu/~mlan        |                     Learn Always. "


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Re: CPU Temperature Patch

[Michel Lanners]

Hi there,

On  20 Sep, this message from D.J. Osguthorpe echoed through cyberspace:
> Note that the intrinsic resolution of the temperature seems to be 4 degrees
> - the values printed are at the mid-point between two 4 degree multiples.

Yes, that is so by design: 5 bit A/D for a range of 0 - 128 degrees.
Found that in some paper on the Thermal Assist Unit (ref. 2 in the
appnote).

By the way, the uncalibrated sensor has an accuracy of +- 12 degrees.


Michel

-------------------------------------------------------------------------
Michel Lanners                 |  " Read Philosophy.  Study Art.
23, Rue Paul Henkes            |    Ask Questions.  Make Mistakes.
L-1710 Luxembourg              |
email   mlan@cpu.lu            |
http://www.cpu.lu/~mlan        |                     Learn Always. "


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