[Skiboot] [PATCH] slw: use only lite stop states for P9 DD1

[Vaidyanathan Srinivasan]

From: Shilpasri G Bhat <shilpa.bhat at linux.vnet.ibm.com>

POWER9 DD1 chip can work with lite stop states now. These
STOP states have ESL=EC=0 and provide fast entry/exit.

Signed-off-by: Shilpasri G Bhat <shilpa.bhat at linux.vnet.ibm.com>
Signed-off-by: Vaidyanathan Srinivasan <svaidy at linux.vnet.ibm.com>
---
 hw/slw.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/hw/slw.c b/hw/slw.c
index 81e4e4a..2415019 100644
--- a/hw/slw.c
+++ b/hw/slw.c
@@ -649,6 +649,8 @@ void add_cpu_idle_state_properties(void)
 	u32 *residency_ns_buf;
 	u32 *flags_buf;
 
+	bool only_lite = false;
+
 	prlog(PR_DEBUG, "CPU idle state device tree init\n");
 
 	/* Create /ibm,opal/power-mgt if it doesn't exist already */
@@ -683,6 +685,9 @@ void add_cpu_idle_state_properties(void)
 		if (!stop_levels)
 			prerror("SLW: No stop levels available. Power saving is disabled!\n");
 
+		/* Force only lite states for DD1.0 */
+		if (chip->ec_level == 0x10)
+			only_lite = true;
 	} else if (chip->type == PROC_CHIP_P8_MURANO ||
 	    chip->type == PROC_CHIP_P8_VENICE ||
 	    chip->type == PROC_CHIP_P8_NAPLES) {
@@ -757,10 +762,15 @@ void add_cpu_idle_state_properties(void)
 			supported_states_mask |= OPAL_PM_WINKLE_ENABLED;
 	}
 	for (i = 0; i < nr_states; i++) {
+		u64 esl = states[i].pm_ctrl_reg_val & OPAL_PM_PSSCR_ESL;
+
 		/* For each state, check if it is one of the supported states. */
 		if (!(states[i].flags & supported_states_mask))
 			continue;
 
+		if (only_lite && esl)
+			continue;
+
 		/* We can only use the stop levels that HB has made available */
 		if (has_stop_inst) {
 			u32 level = 31 - (states[i].pm_ctrl_reg_val &
@@ -770,6 +780,8 @@ void add_cpu_idle_state_properties(void)
 				continue;
 		}
 
+		prlog(PR_NOTICE, "SLW: Enabling: %s\n", states[i].name);
+
 		/*
 		 * If a state is supported add each of its property
 		 * to its corresponding property buffer.
-- 
2.9.3