[PATCH] Add suspend/resume for HPET

This adds support of suspend/resume on i386 for HPET, which fixes a
number of timer-related failures around STR.

Signed-off-by: Maxim Levitsky <maximlevitsky@gmail.com>
Acked-by: Michael S. Tsirkin <mst@dev.mellanox.co.il>
Acked-by: Jeff Chua <jeff.chua.linux@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/i386/kernel/hpet.c

@@ -3,6 +3,8 @@
 #include <linux/errno.h>
 #include <linux/hpet.h>
 #include <linux/init.h>
+#include <linux/sysdev.h>
+#include <linux/pm.h>
 
 #include <asm/hpet.h>
 #include <asm/io.h>
@@ -307,6 +309,7 @@ int __init hpet_enable(void)
 out_nohpet:
 	iounmap(hpet_virt_address);
 	hpet_virt_address = NULL;
+	boot_hpet_disable = 1;
 	return 0;
 }
 
@@ -521,3 +524,68 @@ irqreturn_t hpet_rtc_interrupt(int irq, void *dev_id)
 	return IRQ_HANDLED;
 }
 #endif
+
+
+/*
+ * Suspend/resume part
+ */
+
+#ifdef CONFIG_PM
+
+static int hpet_suspend(struct sys_device *sys_device, pm_message_t state)
+{
+	unsigned long cfg = hpet_readl(HPET_CFG);
+
+	cfg &= ~(HPET_CFG_ENABLE|HPET_CFG_LEGACY);
+	hpet_writel(cfg, HPET_CFG);
+
+	return 0;
+}
+
+static int hpet_resume(struct sys_device *sys_device)
+{
+	unsigned int id;
+
+	hpet_start_counter();
+
+	id = hpet_readl(HPET_ID);
+
+	if (id & HPET_ID_LEGSUP)
+		hpet_enable_int();
+
+	return 0;
+}
+
+static struct sysdev_class hpet_class = {
+	set_kset_name("hpet"),
+	.suspend	= hpet_suspend,
+	.resume		= hpet_resume,
+};
+
+static struct sys_device hpet_device = {
+	.id		= 0,
+	.cls		= &hpet_class,
+};
+
+
+static __init int hpet_register_sysfs(void)
+{
+	int err;
+
+	if (!is_hpet_capable())
+		return 0;
+
+	err = sysdev_class_register(&hpet_class);
+
+	if (!err) {
+		err = sysdev_register(&hpet_device);
+		if (err)
+			sysdev_class_unregister(&hpet_class);
+	}
+
+	return err;
+}
+
+device_initcall(hpet_register_sysfs);
+
+#endif