linux-kernel - [PATCH] driver/cpuidle-powernv: Avoid endianness conversions while parsing DT

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Message-ID: <20150203062810.13207.93694.stgit@preeti.in.ibm.com>
Date:	Tue, 03 Feb 2015 12:01:15 +0530
From:	Preeti U Murthy <preeti@...ux.vnet.ibm.com>
To:	mpe@...erman.id.au
Cc:	stewart@...ux.vnet.ibm.com, rafael.j.wysocki@...el.com,
	linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
	linux-pm@...r.kernel.org
Subject: [PATCH] driver/cpuidle-powernv: Avoid endianness conversions while
 parsing DT

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@...ux.vnet.ibm.com>
---
This patch is based ontop of the mainline + V4 of "cpuidle/powernv:
Read target_residency value of idle states from DT if available".

 drivers/cpuidle/cpuidle-powernv.c |   30 ++++++++++++++++--------------
 1 file changed, 16 insertions(+), 14 deletions(-)

diff --git a/drivers/cpuidle/cpuidle-powernv.c b/drivers/cpuidle/cpuidle-powernv.c
index 3aa27a0..4f76fc7 100644
--- a/drivers/cpuidle/cpuidle-powernv.c
+++ b/drivers/cpuidle/cpuidle-powernv.c
@@ -161,9 +161,7 @@ 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 */
@@ -174,15 +172,19 @@ 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,
@@ -199,21 +201,19 @@ 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 = 0;
 			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");
@@ -236,6 +236,8 @@ 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;
 }

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