ARM: 6074/1: oprofile: convert from sysdev to platform device

This is a reworking of an original patch posted by Aaro Koskinen:

oprofile does not work with PM, because sysdev_suspend() is done with
interrupts disabled and oprofile needs a mutex. Implementing oprofile
as a platform device solves this problem.

Cc: Aaro Koskinen <aaro.koskinen@nokia.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Aaro Koskinen <aaro.koskinen@nokia.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/oprofile/common.c

@@ -10,13 +10,14 @@
  */
 
 #include <linux/cpumask.h>
+#include <linux/err.h>
 #include <linux/errno.h>
 #include <linux/init.h>
 #include <linux/mutex.h>
 #include <linux/oprofile.h>
 #include <linux/perf_event.h>
+#include <linux/platform_device.h>
 #include <linux/slab.h>
-#include <linux/sysdev.h>
 #include <asm/stacktrace.h>
 #include <linux/uaccess.h>
 
@@ -227,7 +228,7 @@ static void op_arm_stop(void)
 }
 
 #ifdef CONFIG_PM
-static int op_arm_suspend(struct sys_device *dev, pm_message_t state)
+static int op_arm_suspend(struct platform_device *dev, pm_message_t state)
 {
 	mutex_lock(&op_arm_mutex);
 	if (op_arm_enabled)
@@ -236,7 +237,7 @@ static int op_arm_suspend(struct sys_device *dev, pm_message_t state)
 	return 0;
 }
 
-static int op_arm_resume(struct sys_device *dev)
+static int op_arm_resume(struct platform_device *dev)
 {
 	mutex_lock(&op_arm_mutex);
 	if (op_arm_enabled && op_perf_start())
@@ -245,34 +246,42 @@ static int op_arm_resume(struct sys_device *dev)
 	return 0;
 }
 
-static struct sysdev_class oprofile_sysclass = {
-	.name		= "oprofile",
+static struct platform_driver oprofile_driver = {
+	.driver		= {
+		.name		= "arm-oprofile",
+	},
 	.resume		= op_arm_resume,
 	.suspend	= op_arm_suspend,
 };
 
-static struct sys_device device_oprofile = {
-	.id		= 0,
-	.cls		= &oprofile_sysclass,
-};
+static struct platform_device *oprofile_pdev;
 
 static int __init init_driverfs(void)
 {
 	int ret;
 
-	if (!(ret = sysdev_class_register(&oprofile_sysclass)))
-		ret = sysdev_register(&device_oprofile);
+	ret = platform_driver_register(&oprofile_driver);
+	if (ret)
+		goto out;
+
+	oprofile_pdev =	platform_device_register_simple(
+				oprofile_driver.driver.name, 0, NULL, 0);
+	if (IS_ERR(oprofile_pdev)) {
+		ret = PTR_ERR(oprofile_pdev);
+		platform_driver_unregister(&oprofile_driver);
+	}
 
+out:
 	return ret;
 }
 
 static void  exit_driverfs(void)
 {
-	sysdev_unregister(&device_oprofile);
-	sysdev_class_unregister(&oprofile_sysclass);
+	platform_device_unregister(oprofile_pdev);
+	platform_driver_unregister(&oprofile_driver);
 }
 #else
-#define init_driverfs()	do { } while (0)
+static int __init init_driverfs(void) { return 0; }
 #define exit_driverfs() do { } while (0)
 #endif /* CONFIG_PM */
 
@@ -353,6 +362,12 @@ int __init oprofile_arch_init(struct oprofile_operations *ops)
 		return -ENOMEM;
 	}
 
+	ret = init_driverfs();
+	if (ret) {
+		kfree(counter_config);
+		return ret;
+	}
+
 	for_each_possible_cpu(cpu) {
 		perf_events[cpu] = kcalloc(perf_num_counters,
 				sizeof(struct perf_event *), GFP_KERNEL);
@@ -365,7 +380,6 @@ int __init oprofile_arch_init(struct oprofile_operations *ops)
 		}
 	}
 
-	init_driverfs();
 	ops->backtrace		= arm_backtrace;
 	ops->create_files	= op_arm_create_files;
 	ops->setup		= op_arm_setup;