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Subject[PATCH 13/16] cell: use ppc_md->power_save instead of cbe_idle_loop
This moves the cell idle function to use the default cpu_idle
with a special power_save callback, like all other platforms
except iSeries already do.

It also makes it possible to disable this power_save function
with a new powerpc-specific boot option "powersave=off".

Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>

Index: linux-2.6/arch/powerpc/kernel/idle.c
===================================================================
--- linux-2.6.orig/arch/powerpc/kernel/idle.c
+++ linux-2.6/arch/powerpc/kernel/idle.c
@@ -39,6 +39,13 @@
#define cpu_should_die() 0
#endif

+static int __init powersave_off(char *arg)
+{
+ ppc_md.power_save = NULL;
+ return 0;
+}
+__setup("powersave=off", powersave_off);
+
/*
* The body of the idle task.
*/
Index: linux-2.6/arch/powerpc/platforms/cell/pervasive.c
===================================================================
--- linux-2.6.orig/arch/powerpc/platforms/cell/pervasive.c
+++ linux-2.6/arch/powerpc/platforms/cell/pervasive.c
@@ -38,32 +38,16 @@
#include "pervasive.h"
#include "cbe_regs.h"

-static DEFINE_SPINLOCK(cbe_pervasive_lock);
-
-static void __init cbe_enable_pause_zero(void)
+static void cbe_power_save(void)
{
- unsigned long thread_switch_control;
- unsigned long temp_register;
- struct cbe_pmd_regs __iomem *pregs;
-
- spin_lock_irq(&cbe_pervasive_lock);
- pregs = cbe_get_cpu_pmd_regs(smp_processor_id());
- if (pregs == NULL)
- goto out;
-
- pr_debug("Power Management: CPU %d\n", smp_processor_id());
-
- /* Enable Pause(0) control bit */
- temp_register = in_be64(&pregs->pmcr);
-
- out_be64(&pregs->pmcr,
- temp_register | CBE_PMD_PAUSE_ZERO_CONTROL);
+ unsigned long ctrl, thread_switch_control;
+ ctrl = mfspr(SPRN_CTRLF);

/* Enable DEC and EE interrupt request */
thread_switch_control = mfspr(SPRN_TSC_CELL);
thread_switch_control |= TSC_CELL_EE_ENABLE | TSC_CELL_EE_BOOST;

- switch ((mfspr(SPRN_CTRLF) & CTRL_CT)) {
+ switch (ctrl & CTRL_CT) {
case CTRL_CT0:
thread_switch_control |= TSC_CELL_DEC_ENABLE_0;
break;
@@ -75,58 +59,21 @@ static void __init cbe_enable_pause_zero
__FUNCTION__);
break;
}
-
mtspr(SPRN_TSC_CELL, thread_switch_control);

-out:
- spin_unlock_irq(&cbe_pervasive_lock);
-}
-
-static void cbe_idle(void)
-{
- unsigned long ctrl;
-
- /* Why do we do that on every idle ? Couldn't that be done once for
- * all or do we lose the state some way ? Also, the pmcr
- * register setting, that can't be set once at boot ? We really want
- * to move that away in order to implement a simple powersave
+ /*
+ * go into low thread priority, medium priority will be
+ * restored for us after wake-up.
*/
- cbe_enable_pause_zero();
+ HMT_low();

- while (1) {
- if (!need_resched()) {
- local_irq_disable();
- while (!need_resched()) {
- /* go into low thread priority */
- HMT_low();
-
- /*
- * atomically disable thread execution
- * and runlatch.
- * External and Decrementer exceptions
- * are still handled when the thread
- * is disabled but now enter in
- * cbe_system_reset_exception()
- */
- ctrl = mfspr(SPRN_CTRLF);
- ctrl &= ~(CTRL_RUNLATCH | CTRL_TE);
- mtspr(SPRN_CTRLT, ctrl);
- }
- /* restore thread prio */
- HMT_medium();
- local_irq_enable();
- }
-
- /*
- * turn runlatch on again before scheduling the
- * process we just woke up
- */
- ppc64_runlatch_on();
-
- preempt_enable_no_resched();
- schedule();
- preempt_disable();
- }
+ /*
+ * atomically disable thread execution and runlatch.
+ * External and Decrementer exceptions are still handled when the
+ * thread is disabled but now enter in cbe_system_reset_exception()
+ */
+ ctrl &= ~(CTRL_RUNLATCH | CTRL_TE);
+ mtspr(SPRN_CTRLT, ctrl);
}

static int cbe_system_reset_exception(struct pt_regs *regs)
@@ -158,9 +105,20 @@ static int cbe_system_reset_exception(st

void __init cbe_pervasive_init(void)
{
+ int cpu;
if (!cpu_has_feature(CPU_FTR_PAUSE_ZERO))
return;

- ppc_md.idle_loop = cbe_idle;
+ for_each_possible_cpu(cpu) {
+ struct cbe_pmd_regs __iomem *regs = cbe_get_cpu_pmd_regs(cpu);
+ if (!regs)
+ continue;
+
+ /* Enable Pause(0) control bit */
+ out_be64(&regs->pmcr, in_be64(&regs->pmcr) |
+ CBE_PMD_PAUSE_ZERO_CONTROL);
+ }
+
+ ppc_md.power_save = cbe_power_save;
ppc_md.system_reset_exception = cbe_system_reset_exception;
}
--

-
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