[PATCH] RTC subsystem: class

Add the basic RTC subsystem infrastructure to the kernel.

rtc/class.c - registration facilities for RTC drivers
rtc/interface.c - kernel/rtc interface functions
rtc/hctosys.c - snippet of code that copies hw clock to sw clock
		at bootup, if configured to do so.

Signed-off-by: Alessandro Zummo <[email protected]>
Acked-by: Greg Kroah-Hartman <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

CREDITS

@@ -3741,10 +3741,11 @@ D: Mylex DAC960 PCI RAID driver
 D: Miscellaneous kernel fixes
 
 N: Alessandro Zummo
-E: [email protected]
-W: http://freepage.logicom.it/azummo/
+E: [email protected]
 D: CMI8330 support is sb_card.c
 D: ISAPnP fixes in sb_card.c
+D: ZyXEL omni.net lcd plus driver
+D: RTC subsystem
 S: Italy
 
 N: Marc Zyngier

MAINTAINERS

@@ -2233,6 +2233,12 @@ M:	[email protected]
 L:	[email protected]
 S:	Maintained
 
+REAL TIME CLOCK (RTC) SUBSYSTEM
+P:	Alessandro Zummo
+M:	[email protected]
+L:	[email protected]
+S:	Maintained
+
 REISERFS FILE SYSTEM
 P:	Hans Reiser
 M:	[email protected]

drivers/rtc/Kconfig

@@ -1,6 +1,46 @@
-#
+\#
 # RTC class/drivers configuration
 #
 
+menu "Real Time Clock"
+
 config RTC_LIB
-	tristate
+	tristate
+
+config RTC_CLASS
+	tristate "RTC class"
+	depends on EXPERIMENTAL
+	default n
+	select RTC_LIB
+	help
+	  Generic RTC class support. If you say yes here, you will
+ 	  be allowed to plug one or more RTCs to your system. You will
+	  probably want to enable one of more of the interfaces below.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called rtc-class.
+
+config RTC_HCTOSYS
+	bool "Set system time from RTC on startup"
+	depends on RTC_CLASS = y
+	default y
+	help
+	  If you say yes here, the system time will be set using
+	  the value read from the specified RTC device. This is useful
+	  in order to avoid unnecessary fschk runs.
+
+config RTC_HCTOSYS_DEVICE
+	string "The RTC to read the time from"
+	depends on RTC_HCTOSYS = y
+	default "rtc0"
+	help
+	  The RTC device that will be used as the source for
+	  the system time, usually rtc0.
+
+comment "RTC interfaces"
+	depends on RTC_CLASS
+
+comment "RTC drivers"
+	depends on RTC_CLASS
+
+endmenu

drivers/rtc/Makefile

@@ -2,4 +2,7 @@
 # Makefile for RTC class/drivers.
 #
 
-obj-$(CONFIG_RTC_LIB)	+= rtc-lib.o
+obj-$(CONFIG_RTC_LIB)		+= rtc-lib.o
+obj-$(CONFIG_RTC_HCTOSYS)	+= hctosys.o
+obj-$(CONFIG_RTC_CLASS)		+= rtc-core.o
+rtc-core-y			:= class.o interface.o

drivers/rtc/class.c

@@ -0,0 +1,145 @@
+/*
+ * RTC subsystem, base class
+ *
+ * Copyright (C) 2005 Tower Technologies
+ * Author: Alessandro Zummo <[email protected]>
+ *
+ * class skeleton from drivers/hwmon/hwmon.c
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+*/
+
+#include <linux/module.h>
+#include <linux/rtc.h>
+#include <linux/kdev_t.h>
+#include <linux/idr.h>
+
+static DEFINE_IDR(rtc_idr);
+static DEFINE_MUTEX(idr_lock);
+struct class *rtc_class;
+
+static void rtc_device_release(struct class_device *class_dev)
+{
+	struct rtc_device *rtc = to_rtc_device(class_dev);
+	mutex_lock(&idr_lock);
+	idr_remove(&rtc_idr, rtc->id);
+	mutex_unlock(&idr_lock);
+	kfree(rtc);
+}
+
+/**
+ * rtc_device_register - register w/ RTC class
+ * @dev: the device to register
+ *
+ * rtc_device_unregister() must be called when the class device is no
+ * longer needed.
+ *
+ * Returns the pointer to the new struct class device.
+ */
+struct rtc_device *rtc_device_register(const char *name, struct device *dev,
+					struct rtc_class_ops *ops,
+					struct module *owner)
+{
+	struct rtc_device *rtc;
+	int id, err;
+
+	if (idr_pre_get(&rtc_idr, GFP_KERNEL) == 0) {
+		err = -ENOMEM;
+		goto exit;
+	}
+
+
+	mutex_lock(&idr_lock);
+	err = idr_get_new(&rtc_idr, NULL, &id);
+	mutex_unlock(&idr_lock);
+
+	if (err < 0)
+		goto exit;
+
+	id = id & MAX_ID_MASK;
+
+	rtc = kzalloc(sizeof(struct rtc_device), GFP_KERNEL);
+	if (rtc == NULL) {
+		err = -ENOMEM;
+		goto exit_idr;
+	}
+
+	rtc->id = id;
+	rtc->ops = ops;
+	rtc->owner = owner;
+	rtc->class_dev.dev = dev;
+	rtc->class_dev.class = rtc_class;
+	rtc->class_dev.release = rtc_device_release;
+
+	mutex_init(&rtc->ops_lock);
+	spin_lock_init(&rtc->irq_lock);
+	spin_lock_init(&rtc->irq_task_lock);
+
+	strlcpy(rtc->name, name, RTC_DEVICE_NAME_SIZE);
+	snprintf(rtc->class_dev.class_id, BUS_ID_SIZE, "rtc%d", id);
+
+	err = class_device_register(&rtc->class_dev);
+	if (err)
+		goto exit_kfree;
+
+	dev_info(dev, "rtc core: registered %s as %s\n",
+			rtc->name, rtc->class_dev.class_id);
+
+	return rtc;
+
+exit_kfree:
+	kfree(rtc);
+
+exit_idr:
+	idr_remove(&rtc_idr, id);
+
+exit:
+	return ERR_PTR(err);
+}
+EXPORT_SYMBOL_GPL(rtc_device_register);
+
+
+/**
+ * rtc_device_unregister - removes the previously registered RTC class device
+ *
+ * @rtc: the RTC class device to destroy
+ */
+void rtc_device_unregister(struct rtc_device *rtc)
+{
+	mutex_lock(&rtc->ops_lock);
+	rtc->ops = NULL;
+	mutex_unlock(&rtc->ops_lock);
+	class_device_unregister(&rtc->class_dev);
+}
+EXPORT_SYMBOL_GPL(rtc_device_unregister);
+
+int rtc_interface_register(struct class_interface *intf)
+{
+	intf->class = rtc_class;
+	return class_interface_register(intf);
+}
+EXPORT_SYMBOL_GPL(rtc_interface_register);
+
+static int __init rtc_init(void)
+{
+	rtc_class = class_create(THIS_MODULE, "rtc");
+	if (IS_ERR(rtc_class)) {
+		printk(KERN_ERR "%s: couldn't create class\n", __FILE__);
+		return PTR_ERR(rtc_class);
+	}
+	return 0;
+}
+
+static void __exit rtc_exit(void)
+{
+	class_destroy(rtc_class);
+}
+
+module_init(rtc_init);
+module_exit(rtc_exit);
+
+MODULE_AUTHOR("Alessandro Zummo <[email protected]>");
+MODULE_DESCRIPTION("RTC class support");
+MODULE_LICENSE("GPL");

drivers/rtc/hctosys.c

@@ -0,0 +1,69 @@
+/*
+ * RTC subsystem, initialize system time on startup
+ *
+ * Copyright (C) 2005 Tower Technologies
+ * Author: Alessandro Zummo <[email protected]>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+*/
+
+#include <linux/rtc.h>
+
+/* IMPORTANT: the RTC only stores whole seconds. It is arbitrary
+ * whether it stores the most close value or the value with partial
+ * seconds truncated. However, it is important that we use it to store
+ * the truncated value. This is because otherwise it is necessary,
+ * in an rtc sync function, to read both xtime.tv_sec and
+ * xtime.tv_nsec. On some processors (i.e. ARM), an atomic read
+ * of >32bits is not possible. So storing the most close value would
+ * slow down the sync API. So here we have the truncated value and
+ * the best guess is to add 0.5s.
+ */
+
+static int __init rtc_hctosys(void)
+{
+	int err;
+	struct rtc_time tm;
+	struct class_device *class_dev = rtc_class_open(CONFIG_RTC_HCTOSYS_DEVICE);
+
+	if (class_dev == NULL) {
+		printk("%s: unable to open rtc device (%s)\n",
+			__FILE__, CONFIG_RTC_HCTOSYS_DEVICE);
+		return -ENODEV;
+	}
+
+	err = rtc_read_time(class_dev, &tm);
+	if (err == 0) {
+		err = rtc_valid_tm(&tm);
+		if (err == 0) {
+			struct timespec tv;
+
+			tv.tv_nsec = NSEC_PER_SEC >> 1;
+
+			rtc_tm_to_time(&tm, &tv.tv_sec);
+
+			do_settimeofday(&tv);
+
+			dev_info(class_dev->dev,
+				"setting the system clock to "
+				"%d-%02d-%02d %02d:%02d:%02d (%u)\n",
+				tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday,
+				tm.tm_hour, tm.tm_min, tm.tm_sec,
+				(unsigned int) tv.tv_sec);
+		}
+		else
+			dev_err(class_dev->dev,
+				"hctosys: invalid date/time\n");
+	}
+	else
+		dev_err(class_dev->dev,
+			"hctosys: unable to read the hardware clock\n");
+
+	rtc_class_close(class_dev);
+
+	return 0;
+}
+
+late_initcall(rtc_hctosys);