[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 <a.zummo@towertech.it>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

5 files changed, 537 insertions, 3 deletions

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 15df7c130fa6..a256f67b78e4 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -1,6 +1,46 @@
-#
+\#
 # RTC class/drivers configuration
 #
 
+menu "Real Time Clock"
+
 config RTC_LIB
-        tristate
\ No newline at end of file
+        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
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index eb9ad77c3e95..7b87f3710dff 100644
--- a/drivers/rtc/Makefile
+++ b/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
diff --git a/drivers/rtc/class.c b/drivers/rtc/class.c
new file mode 100644
index 000000000000..8533936d50d8
--- /dev/null
+++ b/drivers/rtc/class.c
@@ -0,0 +1,145 @@
+/*
+ * RTC subsystem, base class
+ *
+ * Copyright (C) 2005 Tower Technologies
+ * Author: Alessandro Zummo <a.zummo@towertech.it>
+ *
+ * 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 <a.zummo@towerteh.it>");
+MODULE_DESCRIPTION("RTC class support");
+MODULE_LICENSE("GPL");
diff --git a/drivers/rtc/hctosys.c b/drivers/rtc/hctosys.c
new file mode 100644
index 000000000000..d02fe9a0001f
--- /dev/null
+++ b/drivers/rtc/hctosys.c
@@ -0,0 +1,69 @@
+/*
+ * RTC subsystem, initialize system time on startup
+ *
+ * Copyright (C) 2005 Tower Technologies
+ * Author: Alessandro Zummo <a.zummo@towertech.it>
+ *
+ * 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);
diff --git a/drivers/rtc/interface.c b/drivers/rtc/interface.c
new file mode 100644
index 000000000000..56e490709b87
--- /dev/null
+++ b/drivers/rtc/interface.c
@@ -0,0 +1,277 @@
+/*
+ * RTC subsystem, interface functions
+ *
+ * Copyright (C) 2005 Tower Technologies
+ * Author: Alessandro Zummo <a.zummo@towertech.it>
+ *
+ * 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;
+}