[Skiboot] [PATCH 7/9] slw: Limit fused cores P9 to STOP0/1

[Benjamin Herrenschmidt]

Linux doesn't know how to properly restore state on "both halves" of
a fused core, so limit ourselves to STOP states that don't require
HV state restore for bare metal kernels (KVM is still broken) until
we add a new representation for STOP states.

The new representation will have per-state versioning so that we
can control their individual enablement based on whether the OS
has the necessary workarounds to make them work.

Signed-off-by: Benjamin Herrenschmidt <benh at kernel.crashing.org>
---
 hw/slw.c | 67 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 67 insertions(+)

diff --git a/hw/slw.c b/hw/slw.c
index dfa9189b..10907391 100644
--- a/hw/slw.c
+++ b/hw/slw.c
@@ -793,6 +793,70 @@ static struct cpu_idle_states power9_ndd1_cpu_idle_states[] = {
 				 | OPAL_PM_PSSCR_EC,
 		.pm_ctrl_reg_mask = OPAL_PM_PSSCR_MASK }
 };
+
+static struct cpu_idle_states power9_bigcores_cpu_idle_states[] = {
+	{
+		.name = "stop0_lite", /* Enter stop0 with no state loss */
+		.latency_ns = 1000,
+		.residency_ns = 10000,
+		.flags = 0*OPAL_PM_DEC_STOP \
+		       | 0*OPAL_PM_TIMEBASE_STOP  \
+		       | 0*OPAL_PM_LOSE_USER_CONTEXT \
+		       | 0*OPAL_PM_LOSE_HYP_CONTEXT \
+		       | 0*OPAL_PM_LOSE_FULL_CONTEXT \
+		       | 1*OPAL_PM_STOP_INST_FAST,
+		.pm_ctrl_reg_val = OPAL_PM_PSSCR_RL(0) \
+				 | OPAL_PM_PSSCR_MTL(3) \
+				 | OPAL_PM_PSSCR_TR(3),
+		.pm_ctrl_reg_mask = OPAL_PM_PSSCR_MASK },
+	{
+		.name = "stop0",
+		.latency_ns = 2000,
+		.residency_ns = 20000,
+		.flags = 0*OPAL_PM_DEC_STOP \
+		       | 0*OPAL_PM_TIMEBASE_STOP  \
+		       | 1*OPAL_PM_LOSE_USER_CONTEXT \
+		       | 0*OPAL_PM_LOSE_HYP_CONTEXT \
+		       | 0*OPAL_PM_LOSE_FULL_CONTEXT \
+		       | 1*OPAL_PM_STOP_INST_FAST,
+		.pm_ctrl_reg_val = OPAL_PM_PSSCR_RL(0) \
+				 | OPAL_PM_PSSCR_MTL(3) \
+				 | OPAL_PM_PSSCR_TR(3) \
+				 | OPAL_PM_PSSCR_ESL \
+				 | OPAL_PM_PSSCR_EC,
+		.pm_ctrl_reg_mask = OPAL_PM_PSSCR_MASK },
+	{
+		.name = "stop1_lite", /* Enter stop1 with no state loss */
+		.latency_ns = 4900,
+		.residency_ns = 49000,
+		.flags = 0*OPAL_PM_DEC_STOP \
+		       | 0*OPAL_PM_TIMEBASE_STOP  \
+		       | 0*OPAL_PM_LOSE_USER_CONTEXT \
+		       | 0*OPAL_PM_LOSE_HYP_CONTEXT \
+		       | 0*OPAL_PM_LOSE_FULL_CONTEXT \
+		       | 1*OPAL_PM_STOP_INST_FAST,
+		.pm_ctrl_reg_val = OPAL_PM_PSSCR_RL(1) \
+				 | OPAL_PM_PSSCR_MTL(3) \
+				 | OPAL_PM_PSSCR_TR(3),
+		.pm_ctrl_reg_mask = OPAL_PM_PSSCR_MASK },
+	{
+		.name = "stop1",
+		.latency_ns = 5000,
+		.residency_ns = 50000,
+		.flags = 0*OPAL_PM_DEC_STOP \
+		       | 0*OPAL_PM_TIMEBASE_STOP  \
+		       | 1*OPAL_PM_LOSE_USER_CONTEXT \
+		       | 0*OPAL_PM_LOSE_HYP_CONTEXT \
+		       | 0*OPAL_PM_LOSE_FULL_CONTEXT \
+		       | 1*OPAL_PM_STOP_INST_FAST,
+		.pm_ctrl_reg_val = OPAL_PM_PSSCR_RL(1) \
+				 | OPAL_PM_PSSCR_MTL(3) \
+				 | OPAL_PM_PSSCR_TR(3) \
+				 | OPAL_PM_PSSCR_ESL \
+				 | OPAL_PM_PSSCR_EC,
+		.pm_ctrl_reg_mask = OPAL_PM_PSSCR_MASK },
+};
+
 static void slw_late_init_p9(struct proc_chip *chip)
 {
 	struct cpu_thread *c;
@@ -880,6 +944,9 @@ void add_cpu_idle_state_properties(void)
 		    (chip->type == PROC_CHIP_P9_NIMBUS)) {
 			states = power9_ndd1_cpu_idle_states;
 			nr_states = ARRAY_SIZE(power9_ndd1_cpu_idle_states);
+		} else if (this_cpu()->is_fused_core) {
+			states = power9_bigcores_cpu_idle_states;
+			nr_states = ARRAY_SIZE(power9_bigcores_cpu_idle_states);
 		} else {
 			states = power9_cpu_idle_states;
 			nr_states = ARRAY_SIZE(power9_cpu_idle_states);
-- 
2.17.1