1 files changed, 271 insertions, 0 deletions
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);
+}