[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 <[e-mail]>
Acked-by: Greg Kroah-Hartman <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

CREDITS

···
 D: Miscellaneous kernel fixes
 
 N: Alessandro Zummo
-E: [e-mail]
-W: http://freepage.logicom.it/azummo/
+E: [e-mail]
 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

···
 L:	[e-mail]
 S:	Maintained
 
+REAL TIME CLOCK (RTC) SUBSYSTEM
+P:	Alessandro Zummo
+M:	[e-mail]
+L:	[e-mail]
+S:	Maintained
+
 REISERFS FILE SYSTEM
 P:	Hans Reiser
 M:	[e-mail]

drivers/rtc/Kconfig

···
-#
+\#
 # RTC class/drivers configuration
 #
 
+menu "Real Time Clock"
+
 config RTC_LIB
 	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

···
 # 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

···
+/*
+ * RTC subsystem, base class
+ *
+ * Copyright (C) 2005 Tower Technologies
+ * Author: Alessandro Zummo <[e-mail]>
+ *
+ * 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 <[e-mail]>");
+MODULE_DESCRIPTION("RTC class support");
+MODULE_LICENSE("GPL");

drivers/rtc/hctosys.c

···
+/*
+ * RTC subsystem, initialize system time on startup
+ *
+ * Copyright (C) 2005 Tower Technologies
+ * Author: Alessandro Zummo <[e-mail]>
+ *
+ * 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);

drivers/rtc/interface.c

···
+/*
+ * RTC subsystem, interface functions
+ *
+ * Copyright (C) 2005 Tower Technologies
+ * Author: Alessandro Zummo <[e-mail]>
+ *
+ * based on arch/arm/common/rtctime.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/rtc.h>
+
+int rtc_read_time(struct class_device *class_dev, struct rtc_time *tm)
+{
+	int err;
+	struct rtc_device *rtc = to_rtc_device(class_dev);
+
+	err = mutex_lock_interruptible(&rtc->ops_lock);
+	if (err)
+		return -EBUSY;
+
+	if (!rtc->ops)
+		err = -ENODEV;
+	else if (!rtc->ops->read_time)
+		err = -EINVAL;
+	else {
+		memset(tm, 0, sizeof(struct rtc_time));
+		err = rtc->ops->read_time(class_dev->dev, tm);
+	}
+
+	mutex_unlock(&rtc->ops_lock);
+	return err;
+}
+EXPORT_SYMBOL_GPL(rtc_read_time);
+
+int rtc_set_time(struct class_device *class_dev, struct rtc_time *tm)
+{
+	int err;
+	struct rtc_device *rtc = to_rtc_device(class_dev);
+
+	err = rtc_valid_tm(tm);
+	if (err != 0)
+		return err;
+
+	err = mutex_lock_interruptible(&rtc->ops_lock);
+	if (err)
+		return -EBUSY;
+
+	if (!rtc->ops)
+		err = -ENODEV;
+	else if (!rtc->ops->set_time)
+		err = -EINVAL;
+	else
+		err = rtc->ops->set_time(class_dev->dev, tm);
+
+	mutex_unlock(&rtc->ops_lock);
+	return err;
+}
+EXPORT_SYMBOL_GPL(rtc_set_time);
+
+int rtc_set_mmss(struct class_device *class_dev, unsigned long secs)
+{
+	int err;
+	struct rtc_device *rtc = to_rtc_device(class_dev);
+
+	err = mutex_lock_interruptible(&rtc->ops_lock);
+	if (err)
+		return -EBUSY;
+
+	if (!rtc->ops)
+		err = -ENODEV;
+	else if (rtc->ops->set_mmss)
+		err = rtc->ops->set_mmss(class_dev->dev, secs);
+	else if (rtc->ops->read_time && rtc->ops->set_time) {
+		struct rtc_time new, old;
+
+		err = rtc->ops->read_time(class_dev->dev, &old);
+		if (err == 0) {
+			rtc_time_to_tm(secs, &new);
+
+			/*
+			 * avoid writing when we're going to change the day of
+			 * the month. We will retry in the next minute. This
+			 * basically means that if the RTC must not drift
+			 * by more than 1 minute in 11 minutes.
+			 */
+			if (!((old.tm_hour == 23 && old.tm_min == 59) ||
+				(new.tm_hour == 23 && new.tm_min == 59)))
+				err = rtc->ops->set_time(class_dev->dev, &new);
+		}
+	}
+	else
+		err = -EINVAL;
+
+	mutex_unlock(&rtc->ops_lock);
+
+	return err;
+}
+EXPORT_SYMBOL_GPL(rtc_set_mmss);
+
+int rtc_read_alarm(struct class_device *class_dev, struct rtc_wkalrm *alarm)
+{
+	int err;
+	struct rtc_device *rtc = to_rtc_device(class_dev);
+
+	err = mutex_lock_interruptible(&rtc->ops_lock);
+	if (err)
+		return -EBUSY;
+
+	if (rtc->ops == NULL)
+		err = -ENODEV;
+	else if (!rtc->ops->read_alarm)
+		err = -EINVAL;
+	else {
+		memset(alarm, 0, sizeof(struct rtc_wkalrm));
+		err = rtc->ops->read_alarm(class_dev->dev, alarm);
+	}
+
+	mutex_unlock(&rtc->ops_lock);
+	return err;
+}
+EXPORT_SYMBOL_GPL(rtc_read_alarm);
+
+int rtc_set_alarm(struct class_device *class_dev, struct rtc_wkalrm *alarm)
+{
+	int err;
+	struct rtc_device *rtc = to_rtc_device(class_dev);
+
+	err = mutex_lock_interruptible(&rtc->ops_lock);
+	if (err)
+		return -EBUSY;
+
+	if (!rtc->ops)
+		err = -ENODEV;
+	else if (!rtc->ops->set_alarm)
+		err = -EINVAL;
+	else
+		err = rtc->ops->set_alarm(class_dev->dev, alarm);
+
+	mutex_unlock(&rtc->ops_lock);
+	return err;
+}
+EXPORT_SYMBOL_GPL(rtc_set_alarm);
+
+void rtc_update_irq(struct class_device *class_dev,
+		unsigned long num, unsigned long events)
+{
+	struct rtc_device *rtc = to_rtc_device(class_dev);
+
+	spin_lock(&rtc->irq_lock);
+	rtc->irq_data = (rtc->irq_data + (num << 8)) | events;
+	spin_unlock(&rtc->irq_lock);
+
+	spin_lock(&rtc->irq_task_lock);
+	if (rtc->irq_task)
+		rtc->irq_task->func(rtc->irq_task->private_data);
+	spin_unlock(&rtc->irq_task_lock);
+
+	wake_up_interruptible(&rtc->irq_queue);
+	kill_fasync(&rtc->async_queue, SIGIO, POLL_IN);
+}
+EXPORT_SYMBOL_GPL(rtc_update_irq);
+
+struct class_device *rtc_class_open(char *name)
+{
+	struct class_device *class_dev = NULL,
+				*class_dev_tmp;
+
+	down(&rtc_class->sem);
+	list_for_each_entry(class_dev_tmp, &rtc_class->children, node) {
+		if (strncmp(class_dev_tmp->class_id, name, BUS_ID_SIZE) == 0) {
+			class_dev = class_dev_tmp;
+			break;
+		}
+	}
+
+	if (class_dev) {
+		if (!try_module_get(to_rtc_device(class_dev)->owner))
+			class_dev = NULL;
+	}
+	up(&rtc_class->sem);
+
+	return class_dev;
+}
+EXPORT_SYMBOL_GPL(rtc_class_open);
+
+void rtc_class_close(struct class_device *class_dev)
+{
+	module_put(to_rtc_device(class_dev)->owner);
+}
+EXPORT_SYMBOL_GPL(rtc_class_close);
+
+int rtc_irq_register(struct class_device *class_dev, struct rtc_task *task)
+{
+	int retval = -EBUSY;
+	struct rtc_device *rtc = to_rtc_device(class_dev);
+
+	if (task == NULL || task->func == NULL)
+		return -EINVAL;
+
+	spin_lock(&rtc->irq_task_lock);
+	if (rtc->irq_task == NULL) {
+		rtc->irq_task = task;
+		retval = 0;
+	}
+	spin_unlock(&rtc->irq_task_lock);
+
+	return retval;
+}
+EXPORT_SYMBOL_GPL(rtc_irq_register);
+
+void rtc_irq_unregister(struct class_device *class_dev, struct rtc_task *task)
+{
+	struct rtc_device *rtc = to_rtc_device(class_dev);
+
+	spin_lock(&rtc->irq_task_lock);
+	if (rtc->irq_task == task)
+		rtc->irq_task = NULL;
+	spin_unlock(&rtc->irq_task_lock);
+}
+EXPORT_SYMBOL_GPL(rtc_irq_unregister);
+
+int rtc_irq_set_state(struct class_device *class_dev, struct rtc_task *task, int enabled)
+{
+	int err = 0;
+	unsigned long flags;
+	struct rtc_device *rtc = to_rtc_device(class_dev);
+
+	spin_lock_irqsave(&rtc->irq_task_lock, flags);
+	if (rtc->irq_task != task)
+		err = -ENXIO;
+	spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
+
+	if (err == 0)
+		err = rtc->ops->irq_set_state(class_dev->dev, enabled);
+
+	return err;
+}
+EXPORT_SYMBOL_GPL(rtc_irq_set_state);
+
+int rtc_irq_set_freq(struct class_device *class_dev, struct rtc_task *task, int freq)
+{
+	int err = 0, tmp = 0;
+	unsigned long flags;
+	struct rtc_device *rtc = to_rtc_device(class_dev);
+
+	/* allowed range is 2-8192 */
+	if (freq < 2 || freq > 8192)
+		return -EINVAL;
+/*
+	FIXME: this does not belong here, will move where appropriate
+	at a later stage. It cannot hurt right now, trust me :)
+	if ((freq > rtc_max_user_freq) && (!capable(CAP_SYS_RESOURCE)))
+		return -EACCES;
+*/
+	/* check if freq is a power of 2 */
+	while (freq > (1 << tmp))
+		tmp++;
+
+	if (freq != (1 << tmp))
+		return -EINVAL;
+
+	spin_lock_irqsave(&rtc->irq_task_lock, flags);
+	if (rtc->irq_task != task)
+		err = -ENXIO;
+	spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
+
+	if (err == 0) {
+		err = rtc->ops->irq_set_freq(class_dev->dev, freq);
+		if (err == 0)
+			rtc->irq_freq = freq;
+	}
+	return err;
+}

include/linux/rtc.h

···
 #define RTC_PLL_GET	_IOR('p', 0x11, struct rtc_pll_info)  /* Get PLL correction */
 #define RTC_PLL_SET	_IOW('p', 0x12, struct rtc_pll_info)  /* Set PLL correction */
 
+/* interrupt flags */
+#define RTC_IRQF 0x80 /* any of the following is active */
+#define RTC_PF 0x40
+#define RTC_AF 0x20
+#define RTC_UF 0x10
+
 #ifdef __KERNEL__
 
 #include <linux/interrupt.h>
···
 extern int rtc_valid_tm(struct rtc_time *tm);
 extern int rtc_tm_to_time(struct rtc_time *tm, unsigned long *time);
 extern void rtc_time_to_tm(unsigned long time, struct rtc_time *tm);
+
+#include <linux/device.h>
+#include <linux/seq_file.h>
+#include <linux/cdev.h>
+#include <linux/poll.h>
+#include <linux/mutex.h>
+
+extern struct class *rtc_class;
+
+struct rtc_class_ops {
+	int (*open)(struct device *);
+	void (*release)(struct device *);
+	int (*ioctl)(struct device *, unsigned int, unsigned long);
+	int (*read_time)(struct device *, struct rtc_time *);
+	int (*set_time)(struct device *, struct rtc_time *);
+	int (*read_alarm)(struct device *, struct rtc_wkalrm *);
+	int (*set_alarm)(struct device *, struct rtc_wkalrm *);
+	int (*proc)(struct device *, struct seq_file *);
+	int (*set_mmss)(struct device *, unsigned long secs);
+	int (*irq_set_state)(struct device *, int enabled);
+	int (*irq_set_freq)(struct device *, int freq);
+	int (*read_callback)(struct device *, int data);
+};
+
+#define RTC_DEVICE_NAME_SIZE 20
+struct rtc_task;
+
+struct rtc_device
+{
+	struct class_device class_dev;
+	struct module *owner;
+
+	int id;
+	char name[RTC_DEVICE_NAME_SIZE];
+
+	struct rtc_class_ops *ops;
+	struct mutex ops_lock;
+
+	struct class_device *rtc_dev;
+	struct cdev char_dev;
+	struct mutex char_lock;
+
+	unsigned long irq_data;
+	spinlock_t irq_lock;
+	wait_queue_head_t irq_queue;
+	struct fasync_struct *async_queue;
+
+	struct rtc_task *irq_task;
+	spinlock_t irq_task_lock;
+	int irq_freq;
+};
+#define to_rtc_device(d) container_of(d, struct rtc_device, class_dev)
+
+extern struct rtc_device *rtc_device_register(const char *name,
+					struct device *dev,
+					struct rtc_class_ops *ops,
+					struct module *owner);
+extern void rtc_device_unregister(struct rtc_device *rdev);
+extern int rtc_interface_register(struct class_interface *intf);
+
+extern int rtc_read_time(struct class_device *class_dev, struct rtc_time *tm);
+extern int rtc_set_time(struct class_device *class_dev, struct rtc_time *tm);
+extern int rtc_set_mmss(struct class_device *class_dev, unsigned long secs);
+extern int rtc_read_alarm(struct class_device *class_dev,
+			struct rtc_wkalrm *alrm);
+extern int rtc_set_alarm(struct class_device *class_dev,
+				struct rtc_wkalrm *alrm);
+extern void rtc_update_irq(struct class_device *class_dev,
+			unsigned long num, unsigned long events);
+
+extern struct class_device *rtc_class_open(char *name);
+extern void rtc_class_close(struct class_device *class_dev);
+
+extern int rtc_irq_register(struct class_device *class_dev,
+				struct rtc_task *task);
+extern void rtc_irq_unregister(struct class_device *class_dev,
+				struct rtc_task *task);
+extern int rtc_irq_set_state(struct class_device *class_dev,
+				struct rtc_task *task, int enabled);
+extern int rtc_irq_set_freq(struct class_device *class_dev,
+				struct rtc_task *task, int freq);
 
 typedef struct rtc_task {
 	void (*func)(void *private_data);