cpufreq: OMAP: instantiate omap-cpufreq as a platform_driver
As multi-platform build is being adopted by more and more ARM platforms,
initcall function should be used very carefully. For example, when
CONFIG_ARM_OMAP2PLUS_CPUFREQ is built in the kernel, omap_cpufreq_init()
will be called on all the platforms to initialize omap-cpufreq driver.
Further, on OMAP, we now use Soc generic cpufreq-cpu0 driver using device
tree entries. To allow cpufreq-cpu0 and omap-cpufreq drivers to co-exist
for OMAP in a single image, we need to ensure the following:
1. With device tree boot, we use cpufreq-cpu0
2. With non device tree boot, we use omap-cpufreq
In the case of (1), we will have cpu OPPs and regulator registered
as part of the device tree nodes, to ensure that omap-cpufreq
and cpufreq-cpu0 don't conflict in managing the frequency of the
same CPU, we should not permit omap-cpufreq to be probed.
In the case of (2), we will not have the cpufreq-cpu0 device, hence
only omap-cpufreq will be active.
To eliminate this undesired these effects, we change omap-cpufreq
driver to have it instantiated as a platform_driver and register
"omap-cpufreq" device only when booted without device tree nodes on
OMAP platforms.
This allows the following:
a) Will only run on platforms that create the platform_device
"omap-cpufreq".
b) Since the platform_device is registered only when device tree nodes
are *not* populated, omap-cpufreq driver does not conflict with
the usage of cpufreq-cpu0 driver which is used on OMAP platforms when
device tree nodes are present.
Inspired by commit 5553f9e26f6f49a93ba732fd222eac6973a4cf35
(cpufreq: instantiate cpufreq-cpu0 as a platform_driver)
[robherring2@gmail.com: reported conflict of omap-cpufreq vs other
driver in an non-device tree supported boot]
Reported-by: Rob Herring <robherring2@gmail.com>
Signed-off-by: Nishanth Menon <nm@ti.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Kevin Hilman <khilman@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
diff --git a/drivers/cpufreq/omap-cpufreq.c b/drivers/cpufreq/omap-cpufreq.c
index ad7549c..0279d18 100644
--- a/drivers/cpufreq/omap-cpufreq.c
+++ b/drivers/cpufreq/omap-cpufreq.c
@@ -25,6 +25,7 @@
#include <linux/opp.h>
#include <linux/cpu.h>
#include <linux/module.h>
+#include <linux/platform_device.h>
#include <linux/regulator/consumer.h>
#include <asm/smp_plat.h>
@@ -243,7 +244,7 @@
.attr = omap_cpufreq_attr,
};
-static int __init omap_cpufreq_init(void)
+static int omap_cpufreq_probe(struct platform_device *pdev)
{
mpu_dev = get_cpu_device(0);
if (!mpu_dev) {
@@ -271,12 +272,20 @@
return cpufreq_register_driver(&omap_driver);
}
-static void __exit omap_cpufreq_exit(void)
+static int omap_cpufreq_remove(struct platform_device *pdev)
{
- cpufreq_unregister_driver(&omap_driver);
+ return cpufreq_unregister_driver(&omap_driver);
}
+static struct platform_driver omap_cpufreq_platdrv = {
+ .driver = {
+ .name = "omap-cpufreq",
+ .owner = THIS_MODULE,
+ },
+ .probe = omap_cpufreq_probe,
+ .remove = omap_cpufreq_remove,
+};
+module_platform_driver(omap_cpufreq_platdrv);
+
MODULE_DESCRIPTION("cpufreq driver for OMAP SoCs");
MODULE_LICENSE("GPL");
-module_init(omap_cpufreq_init);
-module_exit(omap_cpufreq_exit);