1 files changed, 57 insertions, 90 deletions

diff --git a/arch/powerpc/kernel/tau_6xx.c b/arch/powerpc/kernel/tau_6xx.c
index e2ab8a111b69..0b4694b8d248 100644
--- a/arch/powerpc/kernel/tau_6xx.c
+++ b/arch/powerpc/kernel/tau_6xx.c
@@ -13,13 +13,14 @@
  */
 
 #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 <linux/delay.h>
+#include <linux/workqueue.h>
 
 #include <asm/io.h>
 #include <asm/reg.h>
@@ -39,9 +40,7 @@ static struct tau_temp
 	unsigned char grew;
 } tau[NR_CPUS];
 
-struct timer_list tau_timer;
-
-#undef DEBUG
+static bool tau_int_enable;
 
 /* TODO: put these in a /proc interface, with some sanity checks, and maybe
  * dynamic adjustment to minimize # of interrupts */
@@ -50,72 +49,49 @@ struct timer_list tau_timer;
 #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 shrink_timer	2000	/* period between shrinking the window */
 #define min_window	2	/* minimum window size, degrees C */
 
 static 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);
+	u32 maybe_tie = tau_int_enable ? THRM1_TIE : 0;
 
-	/* setup THRM2,
-	 * threshold, valid bit, enable interrupts, interrupt when above threshold
-	 */
-	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
+	/* setup THRM1, threshold, valid bit, interrupt when below threshold */
+	mtspr(SPRN_THRM1, THRM1_THRES(tau[cpu].low) | THRM1_V | maybe_tie | THRM1_TID);
+
+	/* setup THRM2, threshold, valid bit, interrupt when above threshold */
+	mtspr(SPRN_THRM2, THRM1_THRES(tau[cpu].high) | THRM1_V | maybe_tie);
 }
 
 static void TAUupdate(int cpu)
 {
-	unsigned thrm;
-
-#ifdef DEBUG
-	printk("TAUupdate ");
-#endif
+	u32 thrm;
+	u32 bits = THRM1_TIV | THRM1_TIN | THRM1_V;
 
 	/* 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
+	thrm = mfspr(SPRN_THRM1);
+	if ((thrm & bits) == bits) {
+		mtspr(SPRN_THRM1, 0);
+
+		if (tau[cpu].low >= step_size) {
+			tau[cpu].low -= step_size;
+			tau[cpu].high -= (step_size - window_expand);
 		}
+		tau[cpu].grew = 1;
+		pr_debug("%s: low threshold crossed\n", __func__);
 	}
-	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
+	thrm = mfspr(SPRN_THRM2);
+	if ((thrm & bits) == bits) {
+		mtspr(SPRN_THRM2, 0);
+
+		if (tau[cpu].high <= 127 - step_size) {
+			tau[cpu].low += (step_size - window_expand);
+			tau[cpu].high += step_size;
 		}
+		tau[cpu].grew = 1;
+		pr_debug("%s: high threshold crossed\n", __func__);
 	}
-
-#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
@@ -140,17 +116,16 @@ void TAUException(struct pt_regs * regs)
 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
+	if (!tau_int_enable)
+		TAUupdate(cpu);
+
+	/* Stop thermal sensor comparisons and interrupts */
+	mtspr(SPRN_THRM3, 0);
 
 	size = tau[cpu].high - tau[cpu].low;
 	if (size > min_window && ! tau[cpu].grew) {
@@ -173,32 +148,26 @@ static void tau_timeout(void * info)
 
 	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)
+	/* Restart thermal sensor comparisons and interrupts.
+	 * The "PowerPC 740 and PowerPC 750 Microprocessor Datasheet"
+	 * recommends that "the maximum value be set in THRM3 under all
+	 * conditions."
 	 */
-	mtspr(SPRN_THRM3, THRM3_SITV(500*60) | THRM3_E);
-
-	local_irq_restore(flags);
+	mtspr(SPRN_THRM3, THRM3_SITV(0x1fff) | THRM3_E);
 }
 
-static void tau_timeout_smp(struct timer_list *unused)
-{
+static struct workqueue_struct *tau_workq;
 
-	/* schedule ourselves to be run again */
-	mod_timer(&tau_timer, jiffies + shrink_timer) ;
+static void tau_work_func(struct work_struct *work)
+{
+	msleep(shrink_timer);
 	on_each_cpu(tau_timeout, NULL, 0);
+	/* schedule ourselves to be run again */
+	queue_work(tau_workq, work);
 }
 
+DECLARE_WORK(tau_work, tau_work_func);
+
 /*
  * setup the TAU
  *
@@ -231,21 +200,19 @@ static int __init TAU_init(void)
 		return 1;
 	}
 
+	tau_int_enable = IS_ENABLED(CONFIG_TAU_INT) &&
+			 !strcmp(cur_cpu_spec->platform, "ppc750");
 
-	/* first, set up the window shrinking timer */
-	timer_setup(&tau_timer, tau_timeout_smp, 0);
-	tau_timer.expires = jiffies + shrink_timer;
-	add_timer(&tau_timer);
+	tau_workq = alloc_workqueue("tau", WQ_UNBOUND, 1, 0);
+	if (!tau_workq)
+		return -ENOMEM;
 
 	on_each_cpu(TAU_init_smp, NULL, 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);
+	queue_work(tau_workq, &tau_work);
+
+	pr_info("Thermal assist unit using %s, shrink_timer: %d ms\n",
+		tau_int_enable ? "interrupts" : "workqueue", shrink_timer);
 	tau_initialized = 1;
 
 	return 0;