[PATCH] RTC subsystem: dev interface

Add the dev interface to the RTC subsystem.

Each RTC will be available under /dev/rtcX .  A symlink from /dev/rtc0 to
/dev/rtc cab be obtained with the following udev rule:

KERNEL=="rtc0", SYMLINK+="rtc"

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>

3 files changed, 394 insertions, 0 deletions

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 200fb06b78..8e4dc32058 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -62,6 +62,17 @@ config RTC_INTF_PROC
           This driver can also be built as a module. If so, the module
           will be called rtc-proc.
 
+config RTC_INTF_DEV
+        tristate "dev"
+        depends on RTC_CLASS
+        default RTC_CLASS
+        help
+          Say yes here if you want to use your RTC using the dev
+          interface, /dev/rtc .
+
+          This driver can also be built as a module. If so, the module
+          will be called rtc-dev.
+
 comment "RTC drivers"
         depends on RTC_CLASS
 
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 137aef0e29..38a9212a7f 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -9,3 +9,4 @@ rtc-core-y			:= class.o interface.o
 
 obj-$(CONFIG_RTC_INTF_SYSFS)    += rtc-sysfs.o
 obj-$(CONFIG_RTC_INTF_PROC)     += rtc-proc.o
+obj-$(CONFIG_RTC_INTF_DEV)      += rtc-dev.o
diff --git a/drivers/rtc/rtc-dev.c b/drivers/rtc/rtc-dev.c
new file mode 100644
index 0000000000..b1e3e6179e
--- /dev/null
+++ b/drivers/rtc/rtc-dev.c
@@ -0,0 +1,382 @@
+/*
+ * RTC subsystem, dev interface
+ *
+ * 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/module.h>
+#include <linux/rtc.h>
+
+static struct class *rtc_dev_class;
+static dev_t rtc_devt;
+
+#define RTC_DEV_MAX 16 /* 16 RTCs should be enough for everyone... */
+
+static int rtc_dev_open(struct inode *inode, struct file *file)
+{
+        int err;
+        struct rtc_device *rtc = container_of(inode->i_cdev,
+                                        struct rtc_device, char_dev);
+        struct rtc_class_ops *ops = rtc->ops;
+
+        /* We keep the lock as long as the device is in use
+         * and return immediately if busy
+         */
+        if (!(mutex_trylock(&rtc->char_lock)))
+                return -EBUSY;
+
+        file->private_data = &rtc->class_dev;
+
+        err = ops->open ? ops->open(rtc->class_dev.dev) : 0;
+        if (err == 0) {
+                spin_lock_irq(&rtc->irq_lock);
+                rtc->irq_data = 0;
+                spin_unlock_irq(&rtc->irq_lock);
+
+                return 0;
+        }
+
+        /* something has gone wrong, release the lock */
+        mutex_unlock(&rtc->char_lock);
+        return err;
+}
+
+
+static ssize_t
+rtc_dev_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
+{
+        struct rtc_device *rtc = to_rtc_device(file->private_data);
+
+        DECLARE_WAITQUEUE(wait, current);
+        unsigned long data;
+        ssize_t ret;
+
+        if (count < sizeof(unsigned long))
+                return -EINVAL;
+
+        add_wait_queue(&rtc->irq_queue, &wait);
+        do {
+                __set_current_state(TASK_INTERRUPTIBLE);
+
+                spin_lock_irq(&rtc->irq_lock);
+                data = rtc->irq_data;
+                rtc->irq_data = 0;
+                spin_unlock_irq(&rtc->irq_lock);
+
+                if (data != 0) {
+                        ret = 0;
+                        break;
+                }
+                if (file->f_flags & O_NONBLOCK) {
+                        ret = -EAGAIN;
+                        break;
+                }
+                if (signal_pending(current)) {
+                        ret = -ERESTARTSYS;
+                        break;
+                }
+                schedule();
+        } while (1);
+        set_current_state(TASK_RUNNING);
+        remove_wait_queue(&rtc->irq_queue, &wait);
+
+        if (ret == 0) {
+                /* Check for any data updates */
+                if (rtc->ops->read_callback)
+                        data = rtc->ops->read_callback(rtc->class_dev.dev, data);
+
+                ret = put_user(data, (unsigned long __user *)buf);
+                if (ret == 0)
+                        ret = sizeof(unsigned long);
+        }
+        return ret;
+}
+
+static unsigned int rtc_dev_poll(struct file *file, poll_table *wait)
+{
+        struct rtc_device *rtc = to_rtc_device(file->private_data);
+        unsigned long data;
+
+        poll_wait(file, &rtc->irq_queue, wait);
+
+        data = rtc->irq_data;
+
+        return (data != 0) ? (POLLIN | POLLRDNORM) : 0;
+}
+
+static int rtc_dev_ioctl(struct inode *inode, struct file *file,
+                unsigned int cmd, unsigned long arg)
+{
+        int err = 0;
+        struct class_device *class_dev = file->private_data;
+        struct rtc_device *rtc = to_rtc_device(class_dev);
+        struct rtc_class_ops *ops = rtc->ops;
+        struct rtc_time tm;
+        struct rtc_wkalrm alarm;
+        void __user *uarg = (void __user *) arg;
+
+        /* avoid conflicting IRQ users */
+        if (cmd == RTC_PIE_ON || cmd == RTC_PIE_OFF || cmd == RTC_IRQP_SET) {
+                spin_lock(&rtc->irq_task_lock);
+                if (rtc->irq_task)
+                        err = -EBUSY;
+                spin_unlock(&rtc->irq_task_lock);
+
+                if (err < 0)
+                        return err;
+        }
+
+        /* try the driver's ioctl interface */
+        if (ops->ioctl) {
+                err = ops->ioctl(class_dev->dev, cmd, arg);
+                if (err != -EINVAL)
+                        return err;
+        }
+
+        /* if the driver does not provide the ioctl interface
+         * or if that particular ioctl was not implemented
+         * (-EINVAL), we will try to emulate here.
+         */
+
+        switch (cmd) {
+        case RTC_ALM_READ:
+                err = rtc_read_alarm(class_dev, &alarm);
+                if (err < 0)
+                        return err;
+
+                if (copy_to_user(uarg, &alarm.time, sizeof(tm)))
+                        return -EFAULT;
+                break;
+
+        case RTC_ALM_SET:
+                if (copy_from_user(&alarm.time, uarg, sizeof(tm)))
+                        return -EFAULT;
+
+                alarm.enabled = 0;
+                alarm.pending = 0;
+                alarm.time.tm_mday = -1;
+                alarm.time.tm_mon = -1;
+                alarm.time.tm_year = -1;
+                alarm.time.tm_wday = -1;
+                alarm.time.tm_yday = -1;
+                alarm.time.tm_isdst = -1;
+                err = rtc_set_alarm(class_dev, &alarm);
+                break;
+
+        case RTC_RD_TIME:
+                err = rtc_read_time(class_dev, &tm);
+                if (err < 0)
+                        return err;
+
+                if (copy_to_user(uarg, &tm, sizeof(tm)))
+                        return -EFAULT;
+                break;
+
+        case RTC_SET_TIME:
+                if (!capable(CAP_SYS_TIME))
+                        return -EACCES;
+
+                if (copy_from_user(&tm, uarg, sizeof(tm)))
+                        return -EFAULT;
+
+                err = rtc_set_time(class_dev, &tm);