cpufreq: exynos: Convert exynos-cpufreq to platform driver

To make the driver multiplatform-friendly, unconditional initialization
in an initcall is replaced with a platform driver probed only if
respective platform device is registered.

Tested at: Exynos4210 (TRATS) and Exynos4412 (TRATS2)

Signed-off-by: Lukasz Majewski <l.majewski@samsung.com>
Signed-off-by: Tomasz Figa <t.figa@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Reviewed-by: Sachin Kamat <sachin.kamat@linaro.org>
Tested-by: Sachin Kamat <sachin.kamat@linaro.org>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

arch/arm/mach-exynos/common.c

@@ -303,6 +303,11 @@ void __init exynos_cpuidle_init(void)
 	platform_device_register(&exynos_cpuidle);
 }
 
+void __init exynos_cpufreq_init(void)
+{
+	platform_device_register_simple("exynos-cpufreq", -1, NULL, 0);
+}
+
 void __init exynos_init_late(void)
 {
 	if (of_machine_is_compatible("samsung,exynos5440"))

arch/arm/mach-exynos/common.h

@@ -22,6 +22,7 @@ void exynos_init_io(void);
 void exynos4_restart(enum reboot_mode mode, const char *cmd);
 void exynos5_restart(enum reboot_mode mode, const char *cmd);
 void exynos_cpuidle_init(void);
+void exynos_cpufreq_init(void);
 void exynos_init_late(void);
 
 void exynos_firmware_init(void);

arch/arm/mach-exynos/mach-exynos4-dt.c

@@ -22,6 +22,7 @@
 static void __init exynos4_dt_machine_init(void)
 {
 	exynos_cpuidle_init();
+	exynos_cpufreq_init();
 
 	of_platform_populate(NULL, of_default_bus_match_table, NULL, NULL);
 }

arch/arm/mach-exynos/mach-exynos5-dt.c

@@ -44,6 +44,7 @@ static void __init exynos5_dt_machine_init(void)
 	}
 
 	exynos_cpuidle_init();
+	exynos_cpufreq_init();
 
 	of_platform_populate(NULL, of_default_bus_match_table, NULL, NULL);
 }

drivers/cpufreq/exynos-cpufreq.c

@@ -17,6 +17,7 @@
 #include <linux/regulator/consumer.h>
 #include <linux/cpufreq.h>
 #include <linux/suspend.h>
+#include <linux/platform_device.h>
 
 #include <plat/cpu.h>
 
@@ -232,7 +233,7 @@ static struct cpufreq_driver exynos_driver = {
 #endif
 };
 
-static int __init exynos_cpufreq_init(void)
+static int exynos_cpufreq_probe(struct platform_device *pdev)
 {
 	int ret = -EINVAL;
 
@@ -281,4 +282,12 @@ static int __init exynos_cpufreq_init(void)
 	kfree(exynos_info);
 	return -EINVAL;
 }
-late_initcall(exynos_cpufreq_init);
+
+static struct platform_driver exynos_cpufreq_platdrv = {
+	.driver = {
+		.name	= "exynos-cpufreq",
+		.owner	= THIS_MODULE,
+	},
+	.probe = exynos_cpufreq_probe,
+};
+module_platform_driver(exynos_cpufreq_platdrv);