powerpc: Move cpu_setup_6xx.S and temp.c over to arch/powerpc

Also renamed temp.c to tau_6xx.c (for thermal assist unit) and updated
the Kconfig option description and help text for CONFIG_TAU.

Signed-off-by: Paul Mackerras <paulus@samba.org>

3 files changed, 747 insertions, 1 deletions

diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
index e7fddf1e42c..754c227835b 100644
--- a/arch/powerpc/kernel/Makefile
+++ b/arch/powerpc/kernel/Makefile
@@ -34,7 +34,8 @@ obj-$(CONFIG_IBMEBUS)           += ibmebus.o
 obj-$(CONFIG_GENERIC_TBSYNC)	+= smp-tbsync.o
 obj64-$(CONFIG_PPC_MULTIPLATFORM) += nvram_64.o
 obj-$(CONFIG_CRASH_DUMP)	+= crash_dump.o
-obj-$(CONFIG_6xx)		+= idle_6xx.o l2cr_6xx.o
+obj-$(CONFIG_6xx)		+= idle_6xx.o l2cr_6xx.o cpu_setup_6xx.o
+obj-$(CONFIG_TAU)		+= tau_6xx.o
 
 ifeq ($(CONFIG_PPC_MERGE),y)
 
diff --git a/arch/powerpc/kernel/cpu_setup_6xx.S b/arch/powerpc/kernel/cpu_setup_6xx.S
new file mode 100644
index 00000000000..55ed7716636
--- /dev/null
+++ b/arch/powerpc/kernel/cpu_setup_6xx.S
@@ -0,0 +1,474 @@
+/*
+ * This file contains low level CPU setup functions.
+ *    Copyright (C) 2003 Benjamin Herrenschmidt (benh@kernel.crashing.org)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ *
+ */
+
+#include <linux/config.h>
+#include <asm/processor.h>
+#include <asm/page.h>
+#include <asm/cputable.h>
+#include <asm/ppc_asm.h>
+#include <asm/asm-offsets.h>
+#include <asm/cache.h>
+
+_GLOBAL(__setup_cpu_603)
+	b	setup_common_caches
+_GLOBAL(__setup_cpu_604)
+	mflr	r4
+	bl	setup_common_caches
+	bl	setup_604_hid0
+	mtlr	r4
+	blr
+_GLOBAL(__setup_cpu_750)
+	mflr	r4
+	bl	__init_fpu_registers
+	bl	setup_common_caches
+	bl	setup_750_7400_hid0
+	mtlr	r4
+	blr
+_GLOBAL(__setup_cpu_750cx)
+	mflr	r4
+	bl	__init_fpu_registers
+	bl	setup_common_caches
+	bl	setup_750_7400_hid0
+	bl	setup_750cx
+	mtlr	r4
+	blr
+_GLOBAL(__setup_cpu_750fx)
+	mflr	r4
+	bl	__init_fpu_registers
+	bl	setup_common_caches
+	bl	setup_750_7400_hid0
+	bl	setup_750fx
+	mtlr	r4
+	blr
+_GLOBAL(__setup_cpu_7400)
+	mflr	r4
+	bl	__init_fpu_registers
+	bl	setup_7400_workarounds
+	bl	setup_common_caches
+	bl	setup_750_7400_hid0
+	mtlr	r4
+	blr
+_GLOBAL(__setup_cpu_7410)
+	mflr	r4
+	bl	__init_fpu_registers
+	bl	setup_7410_workarounds
+	bl	setup_common_caches
+	bl	setup_750_7400_hid0
+	li	r3,0
+	mtspr	SPRN_L2CR2,r3
+	mtlr	r4
+	blr
+_GLOBAL(__setup_cpu_745x)
+	mflr	r4
+	bl	setup_common_caches
+	bl	setup_745x_specifics
+	mtlr	r4
+	blr
+
+/* Enable caches for 603's, 604, 750 & 7400 */
+setup_common_caches:
+	mfspr	r11,SPRN_HID0
+	andi.	r0,r11,HID0_DCE
+	ori	r11,r11,HID0_ICE|HID0_DCE
+	ori	r8,r11,HID0_ICFI
+	bne	1f			/* don't invalidate the D-cache */
+	ori	r8,r8,HID0_DCI		/* unless it wasn't enabled */
+1:	sync
+	mtspr	SPRN_HID0,r8		/* enable and invalidate caches */
+	sync
+	mtspr	SPRN_HID0,r11		/* enable caches */
+	sync
+	isync
+	blr
+
+/* 604, 604e, 604ev, ...
+ * Enable superscalar execution & branch history table
+ */
+setup_604_hid0:
+	mfspr	r11,SPRN_HID0
+	ori	r11,r11,HID0_SIED|HID0_BHTE
+	ori	r8,r11,HID0_BTCD
+	sync
+	mtspr	SPRN_HID0,r8	/* flush branch target address cache */
+	sync			/* on 604e/604r */
+	mtspr	SPRN_HID0,r11
+	sync
+	isync
+	blr
+
+/* 7400 <= rev 2.7 and 7410 rev = 1.0 suffer from some
+ * erratas we work around here.
+ * Moto MPC710CE.pdf describes them, those are errata
+ * #3, #4 and #5
+ * Note that we assume the firmware didn't choose to
+ * apply other workarounds (there are other ones documented
+ * in the .pdf). It appear that Apple firmware only works
+ * around #3 and with the same fix we use. We may want to
+ * check if the CPU is using 60x bus mode in which case
+ * the workaround for errata #4 is useless. Also, we may
+ * want to explicitely clear HID0_NOPDST as this is not
+ * needed once we have applied workaround #5 (though it's
+ * not set by Apple's firmware at least).
+ */
+setup_7400_workarounds:
+	mfpvr	r3
+	rlwinm	r3,r3,0,20,31
+	cmpwi	0,r3,0x0207
+	ble	1f
+	blr
+setup_7410_workarounds:
+	mfpvr	r3
+	rlwinm	r3,r3,0,20,31
+	cmpwi	0,r3,0x0100
+	bnelr
+1:
+	mfspr	r11,SPRN_MSSSR0
+	/* Errata #3: Set L1OPQ_SIZE to 0x10 */
+	rlwinm	r11,r11,0,9,6
+	oris	r11,r11,0x0100
+	/* Errata #4: Set L2MQ_SIZE to 1 (check for MPX mode first ?) */
+	oris	r11,r11,0x0002
+	/* Errata #5: Set DRLT_SIZE to 0x01 */
+	rlwinm	r11,r11,0,5,2
+	oris	r11,r11,0x0800
+	sync
+	mtspr	SPRN_MSSSR0,r11
+	sync
+	isync
+	blr
+
+/* 740/750/7400/7410
+ * Enable Store Gathering (SGE), Address Brodcast (ABE),
+ * Branch History Table (BHTE), Branch Target ICache (BTIC)
+ * Dynamic Power Management (DPM), Speculative (SPD)
+ * Clear Instruction cache throttling (ICTC)
+ */
+setup_750_7400_hid0:
+	mfspr	r11,SPRN_HID0
+	ori	r11,r11,HID0_SGE | HID0_ABE | HID0_BHTE | HID0_BTIC
+	oris	r11,r11,HID0_DPM@h
+BEGIN_FTR_SECTION
+	xori	r11,r11,HID0_BTIC
+END_FTR_SECTION_IFSET(CPU_FTR_NO_BTIC)
+BEGIN_FTR_SECTION
+	xoris	r11,r11,HID0_DPM@h	/* disable dynamic power mgmt */
+END_FTR_SECTION_IFSET(CPU_FTR_NO_DPM)
+	li	r3,HID0_SPD
+	andc	r11,r11,r3		/* clear SPD: enable speculative */
+ 	li	r3,0
+ 	mtspr	SPRN_ICTC,r3		/* Instruction Cache Throttling off */
+	isync
+	mtspr	SPRN_HID0,r11
+	sync
+	isync
+	blr
+
+/* 750cx specific
+ * Looks like we have to disable NAP feature for some PLL settings...
+ * (waiting for confirmation)
+ */
+setup_750cx:
+	mfspr	r10, SPRN_HID1
+	rlwinm	r10,r10,4,28,31
+	cmpwi	cr0,r10,7
+	cmpwi	cr1,r10,9
+	cmpwi	cr2,r10,11
+	cror	4*cr0+eq,4*cr0+eq,4*cr1+eq
+	cror	4*cr0+eq,4*cr0+eq,4*cr2+eq
+	bnelr
+	lwz	r6,CPU_SPEC_FEATURES(r5)
+	li	r7,CPU_FTR_CAN_NAP
+	andc	r6,r6,r7
+	stw	r6,CPU_SPEC_FEATURES(r5)
+	blr
+
+/* 750fx specific
+ */
+setup_750fx:
+	blr
+
+/* MPC 745x
+ * Enable Store Gathering (SGE), Branch Folding (FOLD)
+ * Branch History Table (BHTE), Branch Target ICache (BTIC)
+ * Dynamic Power Management (DPM), Speculative (SPD)
+ * Ensure our data cache instructions really operate.
+ * Timebase has to be running or we wouldn't have made it here,
+ * just ensure we don't disable it.
+ * Clear Instruction cache throttling (ICTC)
+ * Enable L2 HW prefetch
+ */
+setup_745x_specifics:
+	/* We check for the presence of an L3 cache setup by
+	 * the firmware. If any, we disable NAP capability as
+	 * it's known to be bogus on rev 2.1 and earlier
+	 */
+	mfspr	r11,SPRN_L3CR
+	andis.	r11,r11,L3CR_L3E@h
+	beq	1f
+	lwz	r6,CPU_SPEC_FEATURES(r5)
+	andi.	r0,r6,CPU_FTR_L3_DISABLE_NAP
+	beq	1f
+	li	r7,CPU_FTR_CAN_NAP
+	andc	r6,r6,r7
+	stw	r6,CPU_SPEC_FEATURES(r5)
+1:
+	mfspr	r11,SPRN_HID0
+
+	/* All of the bits we have to set.....
+	 */
+	ori	r11,r11,HID0_SGE | HID0_FOLD | HID0_BHTE
+	ori	r11,r11,HID0_LRSTK | HID0_BTIC
+	oris	r11,r11,HID0_DPM@h
+BEGIN_FTR_SECTION
+	xori	r11,r11,HID0_BTIC
+END_FTR_SECTION_IFSET(CPU_FTR_NO_BTIC)
+BEGIN_FTR_SECTION
+	xoris	r11,r11,HID0_DPM@h	/* disable dynamic power mgmt */
+END_FTR_SECTION_IFSET(CPU_FTR_NO_DPM)
+
+	/* All of the bits we have to clear....
+	 */
+	li	r3,HID0_SPD | HID0_NOPDST | HID0_NOPTI
+	andc	r11,r11,r3		/* clear SPD: enable speculative */
+ 	li	r3,0
+
+ 	mtspr	SPRN_ICTC,r3		/* Instruction Cache Throttling off */
+	isync
+	mtspr	SPRN_HID0,r11
+	sync
+	isync
+
+	/* Enable L2 HW prefetch, if L2 is enabled
+	 */
+	mfspr	r3,SPRN_L2CR
+	andis.	r3,r3,L2CR_L2E@h
+	beqlr
+	mfspr	r3,SPRN_MSSCR0
+	ori	r3,r3,3
+	sync
+	mtspr	SPRN_MSSCR0,r3
+	sync
+	isync
+	blr
+
+/*
+ * Initialize the FPU registers. This is needed to work around an errata
+ * in some 750 cpus where using a not yet initialized FPU register after
+ * power on reset may hang the CPU
+ */
+_GLOBAL(__init_fpu_registers)
+	mfmsr	r10
+	ori	r11,r10,MSR_FP
+	mtmsr	r11
+	isync
+	addis	r9,r3,empty_zero_page@ha
+	addi	r9,r9,empty_zero_page@l
+	REST_32FPRS(0,r9)
+	sync
+	mtmsr	r10
+	isync
+	blr
+
+
+/* Definitions for the table use to save CPU states */
+#define CS_HID0		0
+#define CS_HID1		4
+#define CS_HID2		8
+#define	CS_MSSCR0	12
+#define CS_MSSSR0	16
+#define CS_ICTRL	20
+#define CS_LDSTCR	24
+#define CS_LDSTDB	28
+#define CS_SIZE		32
+
+	.data
+	.balign	L1_CACHE_BYTES
+cpu_state_storage:
+	.space	CS_SIZE
+	.balign	L1_CACHE_BYTES,0
+	.text
+
+/* Called in normal context to backup CPU 0 state. This
+ * does not include cache settings. This function is also
+ * called for machine sleep. This does not include the MMU
+ * setup, BATs, etc... but rather the "special" registers
+ * like HID0, HID1, MSSCR0, etc...
+ */
+_GLOBAL(__save_cpu_setup)
+	/* Some CR fields are volatile, we back it up all */
+	mfcr	r7
+
+	/* Get storage ptr */
+	lis	r5,cpu_state_storage@h
+	ori	r5,r5,cpu_state_storage@l
+
+	/* Save HID0 (common to all CONFIG_6xx cpus) */
+	mfspr	r3,SPRN_HID0
+	stw	r3,CS_HID0(r5)
+
+	/* Now deal with CPU type dependent registers */
+	mfspr	r3,SPRN_PVR
+	srwi	r3,r3,16
+	cmplwi	cr0,r3,0x8000	/* 7450 */
+	cmplwi	cr1,r3,0x000c	/* 7400 */
+	cmplwi	cr2,r3,0x800c	/* 7410 */
+	cmplwi	cr3,r3,0x8001	/* 7455 */
+	cmplwi	cr4,r3,0x8002	/* 7457 */
+	cmplwi	cr5,r3,0x8003	/* 7447A */
+	cmplwi	cr6,r3,0x7000	/* 750FX */
+	cmplwi	cr7,r3,0x8004	/* 7448 */
+	/* cr1 is 7400 || 7410 */
+	cror	4*cr1+eq,4*cr1+eq,4*cr2+eq
+	/* cr0 is 74xx */
+	cror	4*cr0+eq,4*cr0+eq,4*cr3+eq
+	cror	4*cr0+eq,4*cr0+eq,4*cr4+eq
+	cror	4*cr0+eq,4*cr0+eq,4*cr1+eq
+	cror	4*cr0+eq,4*cr0+eq,4*cr5+eq
+	cror	4*cr0+eq,4*cr0+eq,4*cr7+eq
+	bne	1f
+	/* Backup 74xx specific regs */
+	mfspr	r4,SPRN_MSSCR0
+	stw	r4,CS_MSSCR0(r5)
+	mfspr	r4,SPRN_MSSSR0
+	stw	r4,CS_MSSSR0(r5)
+	beq	cr1,1f
+	/* Backup 745x specific registers */
+	mfspr	r4,SPRN_HID1
+	stw	r4,CS_HID1(r5)
+	mfspr	r4,SPRN_ICTRL
+	stw	r4,CS_ICTRL(r5)
+	mfspr	r4,SPRN_LDSTCR
+	stw	r4,CS_LDSTCR(r5)
+	mfspr	r4,SPRN_LDSTDB
+	stw	r4,CS_LDSTDB(r5)
+1:
+	bne	cr6,1f
+	/* Backup 750FX specific registers */
+	mfspr	r4,SPRN_HID1
+	stw	r4,CS_HID1(r5)
+	/* If rev 2.x, backup HID2 */
+	mfspr	r3,SPRN_PVR
+	andi.	r3,r3,0xff00
+	cmpwi	cr0,r3,0x0200
+	bne	1f
+	mfspr	r4,SPRN_HID2
+	stw	r4,CS_HID2(r5)
+1:
+	mtcr	r7
+	blr
+
+/* Called with no MMU context (typically MSR:IR/DR off) to
+ * restore CPU state as backed up by the previous
+ * function. This does not include cache setting
+ */
+_GLOBAL(__restore_cpu_setup)
+	/* Some CR fields are volatile, we back it up all */
+	mfcr	r7
+
+	/* Get storage ptr */
+	lis	r5,(cpu_state_storage-KERNELBASE)@h
+	ori	r5,r5,cpu_state_storage@l
+
+	/* Restore HID0 */
+	lwz	r3,CS_HID0(r5)
+	sync
+	isync
+	mtspr	SPRN_HID0,r3
+	sync
+	isync
+
+	/* Now deal with CPU type dependent registers */
+	mfspr	r3,SPRN_PVR
+	srwi	r3,r3,16
+	cmplwi	cr0,r3,0x8000	/* 7450 */
+	cmplwi	cr1,r3,0x000c	/* 7400 */
+	cmplwi	cr2,r3,0x800c	/* 7410 */
+	cmplwi	cr3,r3,0x8001	/* 7455 */
+	cmplwi	cr4,r3,0x8002	/* 7457 */
+	cmplwi	cr5,r3,0x8003	/* 7447A */
+	cmplwi	cr6,r3,0x7000	/* 750FX */
+	cmplwi	cr7,r3,0x8004	/* 7448 */
+	/* cr1 is 7400 || 7410 */
+	cror	4*cr1+eq,4*cr1+eq,4*cr2+eq
+	/* cr0 is 74xx */
+	cror	4*cr0+eq,4*cr0+eq,4*cr3+eq
+	cror	4*cr0+eq,4*cr0+eq,4*cr4+eq
+	cror	4*cr0+eq,4*cr0+eq,4*cr1+eq
+	cror	4*cr0+eq,4*cr0+eq,4*cr5+eq
+	cror	4*cr0+eq,4*cr0+eq,4*cr7+eq
+	bne	2f
+	/* Restore 74xx specific regs */
+	lwz	r4,CS_MSSCR0(r5)
+	sync
+	mtspr	SPRN_MSSCR0,r4
+	sync
+	isync
+	lwz	r4,CS_MSSSR0(r5)
+	sync
+	mtspr	SPRN_MSSSR0,r4
+	sync
+	isync
+	bne	cr2,1f
+	/* Clear 7410 L2CR2 */
+	li	r4,0
+	mtspr	SPRN_L2CR2,r4
+1:	beq	cr1,2f
+	/* Restore 745x specific registers */
+	lwz	r4,CS_HID1(r5)
+	sync
+	mtspr	SPRN_HID1,r4
+	isync
+	sync
+	lwz	r4,CS_ICTRL(r5)
+	sync
+	mtspr	SPRN_ICTRL,r4
+	isync
+	sync
+	lwz	r4,CS_LDSTCR(r5)
+	sync
+	mtspr	SPRN_LDSTCR,r4
+	isync
+	sync
+	lwz	r4,CS_LDSTDB(r5)
+	sync
+	mtspr	SPRN_LDSTDB,r4
+	isync
+	sync
+2:	bne	cr6,1f
+	/* Restore 750FX specific registers
+	 * that is restore HID2 on rev 2.x and PLL config & switch
+	 * to PLL 0 on all
+	 */
+	/* If rev 2.x, restore HID2 with low voltage bit cleared */
+	mfspr	r3,SPRN_PVR
+	andi.	r3,r3,0xff00
+	cmpwi	cr0,r3,0x0200
+	bne	4f
+	lwz	r4,CS_HID2(r5)
+	rlwinm	r4,r4,0,19,17
+	mtspr	SPRN_HID2,r4
+	sync
+4:
+	lwz	r4,CS_HID1(r5)
+	rlwinm  r5,r4,0,16,14
+	mtspr	SPRN_HID1,r5
+		/* Wait for PLL to stabilize */
+	mftbl	r5
+3:	mftbl	r6
+	sub	r6,r6,r5
+	cmplwi	cr0,r6,10000
+	ble	3b
+	/* Setup final PLL */
+	mtspr	SPRN_HID1,r4
+1:
+	mtcr	r7
+	blr
+
diff --git a/arch/powerpc/kernel/tau_6xx.c b/arch/powerpc/kernel/tau_6xx.c
new file mode 100644
index 00000000000..26bd8ea35a4
--- /dev/null
+++ b/arch/powerpc/kernel/tau_6xx.c
@@ -0,0 +1,271 @@
+/*
+ * temp.c	Thermal management for cpu's with Thermal Assist Units
+ *
+ * Written by Troy Benjegerdes <hozer@drgw.net>
+ *
+ * TODO:
+ * dynamic power management to limit peak CPU temp (using ICTC)
+ * calibration???
+ *
+ * Silly, crazy ideas: use cpu load (from scheduler) and ICTC to extend battery
+ * life in portables, and add a 'performance/watt' metric somewhere in /proc
+ */
+
+#include <linux/config.h>
+#include <linux/errno.h>
+#include <linux/jiffies.h>
+#include <linux/kernel.h>
+#include <linux/param.h>
+#include <linux/string.h>
+#include <linux/mm.h>
+#include <linux/interrupt.h>
+#include <linux/init.h>
+
+#include <asm/io.h>
+#include <asm/reg.h>
+#include <asm/nvram.h>
+#include <asm/cache.h>
+#include <asm/8xx_immap.h>
+#include <asm/machdep.h>
+
+static struct tau_temp
+{
+	int interrupts;
+	unsigned char low;
+	unsigned char high;
+	unsigned char grew;
+} tau[NR_CPUS];
+
+struct timer_list tau_timer;
+
+#undef DEBUG
+
+/* TODO: put these in a /proc interface, with some sanity checks, and maybe
+ * dynamic adjustment to minimize # of interrupts */
+/* configurable values for step size and how much to expand the window when
+ * we get an interrupt. These are based on the limit that was out of range */
+#define step_size		2	/* step size when temp goes out of range */
+#define window_expand		1	/* expand the window by this much */
+/* configurable values for shrinking the window */
+#define shrink_timer	2*HZ	/* period between shrinking the window */
+#define min_window	2	/* minimum window size, degrees C */
+
+void set_thresholds(unsigned long cpu)
+{
+#ifdef CONFIG_TAU_INT
+	/*
+	 * setup THRM1,
+	 * threshold, valid bit, enable interrupts, interrupt when below threshold
+	 */
+	mtspr(SPRN_THRM1, THRM1_THRES(tau[cpu].low) | THRM1_V | THRM1_TIE | THRM1_TID);
+
+	/* setup THRM2,
+	 * threshold, valid bit, enable interrupts, interrupt when above threshhold
+	 */
+	mtspr (SPRN_THRM2, THRM1_THRES(tau[cpu].high) | THRM1_V | THRM1_TIE);
+#else
+	/* same thing but don't enable interrupts */
+	mtspr(SPRN_THRM1, THRM1_THRES(tau[cpu].low) | THRM1_V | THRM1_TID);
+	mtspr(SPRN_THRM2, THRM1_THRES(tau[cpu].high) | THRM1_V);
+#endif
+}
+
+void TAUupdate(int cpu)
+{
+	unsigned thrm;
+
+#ifdef DEBUG
+	printk("TAUupdate ");
+#endif
+
+	/* if both thresholds are crossed, the step_sizes cancel out
+	 * and the window winds up getting expanded twice. */
+	if((thrm = mfspr(SPRN_THRM1)) & THRM1_TIV){ /* is valid? */
+		if(thrm & THRM1_TIN){ /* crossed low threshold */
+			if (tau[cpu].low >= step_size){
+				tau[cpu].low -= step_size;
+				tau[cpu].high -= (step_size - window_expand);
+			}
+			tau[cpu].grew = 1;
+#ifdef DEBUG
+			printk("low threshold crossed ");
+#endif
+		}
+	}
+	if((thrm = mfspr(SPRN_THRM2)) & THRM1_TIV){ /* is valid? */
+		if(thrm & THRM1_TIN){ /* crossed high threshold */
+			if (tau[cpu].high <= 127-step_size){
+				tau[cpu].low += (step_size - window_expand);
+				tau[cpu].high += step_size;
+			}
+			tau[cpu].grew = 1;
+#ifdef DEBUG
+			printk("high threshold crossed ");
+#endif
+		}
+	}
+
+#ifdef DEBUG
+	printk("grew = %d\n", tau[cpu].grew);
+#endif
+
+#ifndef CONFIG_TAU_INT /* tau_timeout will do this if not using interrupts */
+	set_thresholds(cpu);
+#endif
+
+}
+
+#ifdef CONFIG_TAU_INT
+/*
+ * TAU interrupts - called when we have a thermal assist unit interrupt
+ * with interrupts disabled
+ */
+
+void TAUException(struct pt_regs * regs)
+{
+	int cpu = smp_processor_id();
+
+	irq_enter();
+	tau[cpu].interrupts++;
+
+	TAUupdate(cpu);
+
+	irq_exit();
+}
+#endif /* CONFIG_TAU_INT */
+
+static void tau_timeout(void * info)
+{
+	int cpu;
+	unsigned long flags;
+	int size;
+	int shrink;
+
+	/* disabling interrupts *should* be okay */
+	local_irq_save(flags);
+	cpu = smp_processor_id();
+
+#ifndef CONFIG_TAU_INT
+	TAUupdate(cpu);
+#endif
+
+	size = tau[cpu].high - tau[cpu].low;
+	if (size > min_window && ! tau[cpu].grew) {
+		/* do an exponential shrink of half the amount currently over size */
+		shrink = (2 + size - min_window) / 4;
+		if (shrink) {
+			tau[cpu].low += shrink;
+			tau[cpu].high -= shrink;
+		} else { /* size must have been min_window + 1 */
+			tau[cpu].low += 1;
+#if 1 /* debug */
+			if ((tau[cpu].high - tau[cpu].low) != min_window){
+				printk(KERN_ERR "temp.c: line %d, logic error\n", __LINE__);
+			}
+#endif
+		}
+	}
+
+	tau[cpu].grew = 0;
+
+	set_thresholds(cpu);
+
+	/*
+	 * Do the enable every time, since otherwise a bunch of (relatively)
+	 * complex sleep code needs to be added. One mtspr every time
+	 * tau_timeout is called is probably not a big deal.
+	 *
+	 * Enable thermal sensor and set up sample interval timer
+	 * need 20 us to do the compare.. until a nice 'cpu_speed' function
+	 * call is implemented, just assume a 500 mhz clock. It doesn't really
+	 * matter if we take too long for a compare since it's all interrupt
+	 * driven anyway.
+	 *
+	 * use a extra long time.. (60 us @ 500 mhz)
+	 */
+	mtspr(SPRN_THRM3, THRM3_SITV(500*60) | THRM3_E);
+
+	local_irq_restore(flags);
+}
+
+static void tau_timeout_smp(unsigned long unused)
+{
+
+	/* schedule ourselves to be run again */
+	mod_timer(&tau_timer, jiffies + shrink_timer) ;
+	on_each_cpu(tau_timeout, NULL, 1, 0);
+}
+
+/*
+ * setup the TAU
+ *
+ * Set things up to use THRM1 as a temperature lower bound, and THRM2 as an upper bound.
+ * Start off at zero
+ */
+
+int tau_initialized = 0;
+
+void __init TAU_init_smp(void * info)
+{
+	unsigned long cpu = smp_processor_id();
+
+	/* set these to a reasonable value and let the timer shrink the
+	 * window */
+	tau[cpu].low = 5;
+	tau[cpu].high = 120;
+
+	set_thresholds(cpu);
+}
+
+int __init TAU_init(void)
+{
+	/* We assume in SMP that if one CPU has TAU support, they
+	 * all have it --BenH
+	 */
+	if (!cpu_has_feature(CPU_FTR_TAU)) {
+		printk("Thermal assist unit not available\n");
+		tau_initialized = 0;
+		return 1;
+	}
+
+
+	/* first, set up the window shrinking timer */
+	init_timer(&tau_timer);
+	tau_timer.function = tau_timeout_smp;
+	tau_timer.expires = jiffies + shrink_timer;
+	add_timer(&tau_timer);
+
+	on_each_cpu(TAU_init_smp, NULL, 1, 0);
+
+	printk("Thermal assist unit ");
+#ifdef CONFIG_TAU_INT
+	printk("using interrupts, ");
+#else
+	printk("using timers, ");
+#endif
+	printk("shrink_timer: %d jiffies\n", shrink_timer);
+	tau_initialized = 1;
+
+	return 0;
+}
+
+__initcall(TAU_init);
+
+/*
+ * return current temp
+ */
+
+u32 cpu_temp_both(unsigned long cpu)
+{
+	return ((tau[cpu].high << 16) | tau[cpu].low);
+}
+
+int cpu_temp(unsigned long cpu)
+{
+	return ((tau[cpu].high + tau[cpu].low) / 2);
+}
+
+int tau_interrupts(unsigned long cpu)
+{
+	return (tau[cpu].interrupts);
+}