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Subject[RFC 2/3] powernv/cpuidle : Interface for an idle-stop dependency structure
Date
This patch introduces the idea of having a dependency structure for
idle-stop. The structure encapsulates the following:
1. Bitmask for version of idle-stop
2. Bitmask for propterties like ENABLE/DISABLE
3. Function pointer which helps handle how the stop must be invoked

This patch lays a foundation for other idle-stop versions to be added
and handled cleanly based on their specified requirments.
Currently it handles the existing "idle-stop" version by setting the
discovery bits and the function pointer.

Earlier this patch was posted as part of this series :
https://lkml.org/lkml/2020/3/4/589

Signed-off-by: Pratik Rajesh Sampat <psampat@linux.ibm.com>
Signed-off-by: Abhishek Goel <huntbag@linux.vnet.ibm.com>
---

v1->v2: This patch is newly added in this series.

arch/powerpc/include/asm/processor.h | 17 +++++++++++++++++
arch/powerpc/kernel/dt_cpu_ftrs.c | 5 +++++
arch/powerpc/platforms/powernv/idle.c | 18 ++++++++++++++----
drivers/cpuidle/cpuidle-powernv.c | 3 ++-
4 files changed, 38 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/include/asm/processor.h b/arch/powerpc/include/asm/processor.h
index eedcbfb9a6ff..66fa20476d0e 100644
--- a/arch/powerpc/include/asm/processor.h
+++ b/arch/powerpc/include/asm/processor.h
@@ -429,6 +429,23 @@ extern void power4_idle_nap(void);
extern unsigned long cpuidle_disable;
enum idle_boot_override {IDLE_NO_OVERRIDE = 0, IDLE_POWERSAVE_OFF};

+#define STOP_ENABLE 0x00000001
+
+#define STOP_VERSION_P9 0x1
+
+/*
+ * Classify the dependencies of the stop states
+ * @idle_stop: function handler to handle the quirk stop version
+ * @cpuidle_prop: Signify support for stop states through kernel and/or firmware
+ * @stop_version: Classify quirk versions for stop states
+ */
+typedef struct {
+ unsigned long (*idle_stop)(unsigned long psscr, bool mmu_on);
+ uint8_t cpuidle_prop;
+ uint8_t stop_version;
+} stop_deps_t;
+extern stop_deps_t stop_dep;
+
extern int powersave_nap; /* set if nap mode can be used in idle loop */

extern void power7_idle_type(unsigned long type);
diff --git a/arch/powerpc/kernel/dt_cpu_ftrs.c b/arch/powerpc/kernel/dt_cpu_ftrs.c
index 182b4047c1ef..db1a525e090d 100644
--- a/arch/powerpc/kernel/dt_cpu_ftrs.c
+++ b/arch/powerpc/kernel/dt_cpu_ftrs.c
@@ -292,6 +292,8 @@ static int __init feat_enable_idle_stop(struct dt_cpu_feature *f)
lpcr |= LPCR_PECE1;
lpcr |= LPCR_PECE2;
mtspr(SPRN_LPCR, lpcr);
+ stop_dep.cpuidle_prop |= STOP_ENABLE;
+ stop_dep.stop_version = STOP_VERSION_P9;

return 1;
}
@@ -657,6 +659,9 @@ static void __init cpufeatures_setup_start(u32 isa)
}
}

+stop_deps_t stop_dep = {NULL, 0x0, 0x0};
+EXPORT_SYMBOL(stop_dep);
+
static bool __init cpufeatures_process_feature(struct dt_cpu_feature *f)
{
const struct dt_cpu_feature_match *m;
diff --git a/arch/powerpc/platforms/powernv/idle.c b/arch/powerpc/platforms/powernv/idle.c
index 1841027b25c5..538f0842ac3f 100644
--- a/arch/powerpc/platforms/powernv/idle.c
+++ b/arch/powerpc/platforms/powernv/idle.c
@@ -842,7 +842,7 @@ static unsigned long power9_offline_stop(unsigned long psscr)

#ifndef CONFIG_KVM_BOOK3S_HV_POSSIBLE
__ppc64_runlatch_off();
- srr1 = power9_idle_stop(psscr, true);
+ srr1 = stop_dep.idle_stop(psscr, true);
__ppc64_runlatch_on();
#else
/*
@@ -858,7 +858,7 @@ static unsigned long power9_offline_stop(unsigned long psscr)
local_paca->kvm_hstate.hwthread_state = KVM_HWTHREAD_IN_IDLE;

__ppc64_runlatch_off();
- srr1 = power9_idle_stop(psscr, false);
+ srr1 = stop_dep.idle_stop(psscr, true);
__ppc64_runlatch_on();

local_paca->kvm_hstate.hwthread_state = KVM_HWTHREAD_IN_KERNEL;
@@ -886,7 +886,7 @@ void power9_idle_type(unsigned long stop_psscr_val,
psscr = (psscr & ~stop_psscr_mask) | stop_psscr_val;

__ppc64_runlatch_off();
- srr1 = power9_idle_stop(psscr, true);
+ srr1 = stop_dep.idle_stop(psscr, true);
__ppc64_runlatch_on();

fini_irq_for_idle_irqsoff();
@@ -1390,8 +1390,18 @@ static int __init pnv_init_idle_states(void)
nr_pnv_idle_states = 0;
supported_cpuidle_states = 0;

- if (cpuidle_disable != IDLE_NO_OVERRIDE)
+ if (cpuidle_disable != IDLE_NO_OVERRIDE ||
+ !(stop_dep.cpuidle_prop & STOP_ENABLE))
goto out;
+
+ /* Check for supported version in kernel */
+ if (stop_dep.stop_version & STOP_VERSION_P9) {
+ stop_dep.idle_stop = power9_idle_stop;
+ } else {
+ stop_dep.idle_stop = NULL;
+ goto out;
+ }
+
rc = pnv_parse_cpuidle_dt();
if (rc)
return rc;
diff --git a/drivers/cpuidle/cpuidle-powernv.c b/drivers/cpuidle/cpuidle-powernv.c
index 1b299e801f74..7430a8edf5c9 100644
--- a/drivers/cpuidle/cpuidle-powernv.c
+++ b/drivers/cpuidle/cpuidle-powernv.c
@@ -371,7 +371,8 @@ static int powernv_add_idle_states(void)
*/
static int powernv_idle_probe(void)
{
- if (cpuidle_disable != IDLE_NO_OVERRIDE)
+ if (cpuidle_disable != IDLE_NO_OVERRIDE ||
+ !(stop_dep.cpuidle_prop & STOP_ENABLE))
return -ENODEV;

if (firmware_has_feature(FW_FEATURE_OPAL)) {
--
2.17.1
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