Add platform driver object

include/linux/platform.h

+/*
+ * include/linux/platform.h - platform driver definitions
+ *
+ * Because of the prolific consumerism of the average American,
+ * and the dominant marketing budgets of PC OEMs, we have been
+ * blessed with frequent updates of the PC architecture. 
+ *
+ * While most of these calls are singular per architecture, they 
+ * require an extra layer of abstraction on the x86 so the right
+ * subsystem gets the right call. 
+ *
+ * Basically, this consolidates the power off and reboot callbacks 
+ * into one structure, as well as adding power management hooks.
+ *
+ * When adding a platform driver, please make sure all callbacks are 
+ * filled. There are defaults defined below that do nothing; use those
+ * if you do not support that callback.
+ */ 
+
+#ifndef _PLATFORM_H_
+#define _PLATFORM_H_
+#ifdef __KERNEL__
+
+#include <linux/types.h>
+
+struct platform_t {
+	char	* name;
+	u32	suspend_states;
+	void	(*reboot)(char * cmd);
+	void	(*halt)(void);
+	void	(*power_off)(void);
+	int	(*suspend)(int state, int flags);
+	void	(*idle)(void);
+};
+
+extern struct platform_t * platform;
+extern void default_reboot(char * cmd);
+extern void default_halt(void);
+extern int default_suspend(int state, int flags);
+extern void default_idle(void);
+
+#endif /* __KERNEL__ */
+#endif /* _PLATFORM_H */

kernel/Makefile

@@ -10,12 +10,12 @@
 O_TARGET := kernel.o
 
 export-objs = signal.o sys.o kmod.o context.o ksyms.o pm.o exec_domain.o \
-		printk.o 
+		printk.o platform.o 
 
 obj-y     = sched.o dma.o fork.o exec_domain.o panic.o printk.o \
 	    module.o exit.o itimer.o info.o time.o softirq.o resource.o \
 	    sysctl.o capability.o ptrace.o timer.o user.o \
-	    signal.o sys.o kmod.o context.o futex.o
+	    signal.o sys.o kmod.o context.o futex.o platform.o
 
 obj-$(CONFIG_UID16) += uid16.o
 obj-$(CONFIG_MODULES) += ksyms.o

kernel/platform.c

+/*
+ * platform driver support 
+ */
+
+#include <linux/platform.h>
+#include <linux/module.h>
+#include <linux/errno.h>
+
+static struct platform_t default_platform;
+
+struct platform_t * platform = &default_platform;
+static spinlock_t platform_lock = SPIN_LOCK_UNLOCKED;
+
+void default_reboot(char * cmd)
+{
+	/* nothing */
+}
+
+void default_halt(void)
+{
+	/* nothing */
+}
+
+int default_suspend(int state, int flags)
+{
+	return -ENOSYS;
+}
+
+static struct platform_t default_platform = {
+	name:		"Default Platform",
+	suspend_states:	0,
+	reboot:		default_reboot,
+	halt:		default_halt,
+	power_off:	default_halt,
+	suspend:	default_suspend,
+	idle:		default_idle,
+};
+
+/**
+ * set_platform_driver - set the platform driver.
+ * @pf:	driver to set it to
+ *
+ * Return -EEXIST if someone else already owns it.
+ */
+int set_platform_driver(struct platform_t * pf)
+{
+	if (!pf)
+		return -EINVAL;
+	spin_lock(&platform_lock);
+	if (platform != &default_platform) {
+		spin_unlock(&platform_lock);
+		return -EEXIST;
+	}
+	platform = pf;
+	spin_unlock(&platform_lock);
+	return 0;
+}
+
+void remove_platform_driver(struct platform_t * pf)
+{
+	spin_lock(&platform_lock);
+	if (platform == pf)
+		platform = &default_platform;
+	spin_unlock(&platform_lock);
+}
+
+EXPORT_SYMBOL(default_reboot);
+EXPORT_SYMBOL(default_halt);
+EXPORT_SYMBOL(default_suspend);
+
+EXPORT_SYMBOL(platform);
+EXPORT_SYMBOL(set_platform_driver);
+EXPORT_SYMBOL(remove_platform_driver);