On Mon, Mar 09 2015 at 15:29 -0600, Andy Gross wrote:

On Mon, Mar 09, 2015 at 09:16:36AM -0600, Lina Iyer wrote:

quoted

From: Daniel Lezcano <redacted>

Some architectures have some cpus which does not support idle states.

Let the underlying low level code to return -ENOSYS when it is not
possible to set an idle state.

Signed-off-by: Daniel Lezcano <redacted>
Signed-off-by: Lina Iyer <redacted>
[Minor clean ups and fixes of the per-cpu variable]
---
 drivers/cpuidle/cpuidle-arm.c | 34 +++++++++++++++++++++++++++++++++-
 1 file changed, 33 insertions(+), 1 deletion(-)

diff --git a/drivers/cpuidle/cpuidle-arm.c b/drivers/cpuidle/cpuidle-arm.c
index 1c94b88..f7cdb73 100644
--- a/drivers/cpuidle/cpuidle-arm.c
+++ b/drivers/cpuidle/cpuidle-arm.c

@@ -17,11 +17,14 @@
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/of.h>
+#include <linux/slab.h>

 #include <asm/cpuidle.h>

 #include "dt_idle_states.h"

+static DEFINE_PER_CPU(struct cpuidle_device, *cpuidle_arm_dev);
+
 /*
  * arm_enter_idle_state - Programs CPU to enter the specified state
  *

@@ -93,6 +96,7 @@ static const struct of_device_id arm_idle_state_match[] __initconst = {
 static int __init arm_idle_init(void)
 {
 	int cpu, ret;
+	struct cpuidle_device *dev;
 	struct cpuidle_driver *drv = &arm_idle_driver;

 	/*

@@ -105,18 +109,46 @@ static int __init arm_idle_init(void)
 	if (ret <= 0)
 		return ret ? : -ENODEV;

+
+	ret = cpuidle_register_driver(drv);
+	if (ret) {
+		pr_err("Failed to register cpuidle driver\n");
+		return ret;
+	}
+
 	/*
 	 * Call arch CPU operations in order to initialize
 	 * idle states suspend back-end specific data
 	 */
 	for_each_possible_cpu(cpu) {
+
 		ret = arm_cpuidle_init(cpu);
+		/*
+		 * This cpu does not support any idle states
+		 */
+		if (ret == -ENOSYS)
+			continue;
+
 		if (ret) {
 			pr_err("CPU %d failed to init idle CPU ops\n", cpu);
 			return ret;
 		}
+
+		dev = kzalloc(sizeof(*dev), GFP_KERNEL);

devm_kzalloc?  Otherwise, failures could lead to lost memory.

I dont have a local device to work with for allocation. May be I can get
the cpu device node and the device therefore for allocation. Thoughts?

quoted

+		if (!dev)
+			return -ENOMEM;
+
+		dev->cpu = cpu;
+		ret = cpuidle_register_device(dev);
+		if (ret) {
+			pr_err("Failed to register cpuidle device for CPU %d\n",
+			       cpu);
+			return ret;
+		}
+
+		per_cpu(cpuidle_arm_dev, cpu) = dev;
 	}

-	return cpuidle_register(drv, NULL);
+	return 0;
 }
 device_initcall(arm_idle_init);
--
2.1.0

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