[Utopic][SRU][PATCH 3/3] cpuidle: powernv: Avoid endianness conversions while parsing DT

[Chris J Arges]

From: Preeti U Murthy <preeti at linux.vnet.ibm.com>

BugLink: http://bugs.launchpad.net/bugs/1470404

We currently read the information about idle states from the DT
so as to populate the cpuidle table. Use those APIs to read from
the DT that can avoid endianness conversions of the property values
in the cpuidle driver.

Signed-off-by: Preeti U Murthy <preeti at linux.vnet.ibm.com>
Acked-by: Michael Ellerman <mpe at ellerman.id.au>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki at intel.com>
(cherry picked from commit 70734a786acfd1998e47d40df19cba5c29469bdf)
Signed-off-by: Chris J Arges <chris.j.arges at canonical.com>
---
 drivers/cpuidle/cpuidle-powernv.c | 29 ++++++++++++++++-------------
 1 file changed, 16 insertions(+), 13 deletions(-)

diff --git a/drivers/cpuidle/cpuidle-powernv.c b/drivers/cpuidle/cpuidle-powernv.c
index 8632027..5859c20 100644
--- a/drivers/cpuidle/cpuidle-powernv.c
+++ b/drivers/cpuidle/cpuidle-powernv.c
@@ -160,9 +160,7 @@ static int powernv_add_idle_states(void)
 	struct device_node *power_mgt;
 	int nr_idle_states = 1; /* Snooze */
 	int dt_idle_states;
-	const __be32 *idle_state_flags;
-	u32 len_flags, flags;
-	u32 *latency_ns, *residency_ns;
+	u32 *latency_ns, *residency_ns, *flags;
 	int i, rc;
 
 	/* Currently we have snooze statically defined */
@@ -173,14 +171,19 @@ static int powernv_add_idle_states(void)
 		goto out;
 	}
 
-	idle_state_flags = of_get_property(power_mgt,
-				"ibm,cpu-idle-state-flags", &len_flags);
-	if (!idle_state_flags) {
-		pr_warn("cpuidle-powernv: missing ibm,cpu-idle-state-flags in DT\n");
+	/* Read values of any property to determine the num of idle states */
+	dt_idle_states = of_property_count_u32_elems(power_mgt, "ibm,cpu-idle-state-flags");
+	if (dt_idle_states < 0) {
+		pr_warn("cpuidle-powernv: no idle states found in the DT\n");
 		goto out;
 	}
 
-	dt_idle_states = len_flags / sizeof(u32);
+	flags = kzalloc(sizeof(*flags) * dt_idle_states, GFP_KERNEL);
+	if (of_property_read_u32_array(power_mgt,
+			"ibm,cpu-idle-state-flags", flags, dt_idle_states)) {
+		pr_warn("cpuidle-powernv : missing ibm,cpu-idle-state-flags in DT\n");
+		goto out_free_flags;
+	}
 
 	latency_ns = kzalloc(sizeof(*latency_ns) * dt_idle_states, GFP_KERNEL);
 	rc = of_property_read_u32_array(power_mgt,
@@ -196,21 +199,19 @@ static int powernv_add_idle_states(void)
 
 	for (i = 0; i < dt_idle_states; i++) {
 
-		flags = be32_to_cpu(idle_state_flags[i]);
-
 		/*
 		 * Cpuidle accepts exit_latency and target_residency in us.
 		 * Use default target_residency values if f/w does not expose it.
 		 */
-		if (flags & OPAL_PM_NAP_ENABLED) {
+		if (flags[i] & OPAL_PM_NAP_ENABLED) {
 			/* Add NAP state */
 			strcpy(powernv_states[nr_idle_states].name, "Nap");
 			strcpy(powernv_states[nr_idle_states].desc, "Nap");
 			powernv_states[nr_idle_states].flags = CPUIDLE_FLAG_TIME_VALID;
 			powernv_states[nr_idle_states].target_residency = 100;
 			powernv_states[nr_idle_states].enter = &nap_loop;
-		} else if (flags & OPAL_PM_SLEEP_ENABLED ||
-			flags & OPAL_PM_SLEEP_ENABLED_ER1) {
+		} else if (flags[i] & OPAL_PM_SLEEP_ENABLED ||
+			flags[i] & OPAL_PM_SLEEP_ENABLED_ER1) {
 			/* Add FASTSLEEP state */
 			strcpy(powernv_states[nr_idle_states].name, "FastSleep");
 			strcpy(powernv_states[nr_idle_states].desc, "FastSleep");
@@ -234,6 +235,8 @@ static int powernv_add_idle_states(void)
 	kfree(residency_ns);
 out_free_latency:
 	kfree(latency_ns);
+out_free_flags:
+	kfree(flags);
 out:
 	return nr_idle_states;
 }
-- 
1.9.1