[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>

1 files changed, 382 insertions, 0 deletions

diff --git a/drivers/rtc/rtc-dev.c b/drivers/rtc/rtc-dev.c
new file mode 100644
index 000000000000..b1e3e6179e56
--- /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);
+                break;
+#if 0
+        case RTC_EPOCH_SET:
+#ifndef rtc_epoch
+                /*
+                 * There were no RTC clocks before 1900.
+                 */
+                if (arg < 1900) {
+                        err = -EINVAL;
+                        break;
+                }
+                if (!capable(CAP_SYS_TIME)) {
+                        err = -EACCES;
+                        break;
+                }
+                rtc_epoch = arg;
+                err = 0;
+#endif
+                break;
+
+        case RTC_EPOCH_READ:
+                err = put_user(rtc_epoch, (unsigned long __user *)uarg);
+                break;
+#endif
+        case RTC_WKALM_SET:
+                if (copy_from_user(&alarm, uarg, sizeof(alarm)))
+                        return -EFAULT;
+
+                err = rtc_set_alarm(class_dev, &alarm);
+                break;
+
+        case RTC_WKALM_RD:
+                err = rtc_read_alarm(class_dev, &alarm);
+                if (err < 0)
+                        return err;
+
+                if (copy_to_user(uarg, &alarm, sizeof(alarm)))
+                        return -EFAULT;
+                break;
+
+        default:
+                err = -EINVAL;
+                break;
+        }
+
+        return err;
+}
+
+static int rtc_dev_release(struct inode *inode, struct file *file)
+{
+        struct rtc_device *rtc = to_rtc_device(file->private_data);
+
+        if (rtc->ops->release)
+                rtc->ops->release(rtc->class_dev.dev);
+
+        mutex_unlock(&rtc->char_lock);
+        return 0;
+}
+
+static int rtc_dev_fasync(int fd, struct file *file, int on)
+{
+        struct rtc_device *rtc = to_rtc_device(file->private_data);
+        return fasync_helper(fd, file, on, &rtc->async_queue);
+}
+
+static struct file_operations rtc_dev_fops = {
+        .owner          = THIS_MODULE,
+        .llseek         = no_llseek,
+        .read           = rtc_dev_read,
+        .poll           = rtc_dev_poll,
+        .ioctl          = rtc_dev_ioctl,
+        .open           = rtc_dev_open,
+        .release        = rtc_dev_release,
+        .fasync         = rtc_dev_fasync,
+};
+
+/* insertion/removal hooks */
+
+static int rtc_dev_add_device(struct class_device *class_dev,
+                                struct class_interface *class_intf)
+{
+        int err = 0;
+        struct rtc_device *rtc = to_rtc_device(class_dev);
+
+        if (rtc->id >= RTC_DEV_MAX) {
+                dev_err(class_dev->dev, "too many RTCs\n");
+                return -EINVAL;
+        }
+
+        mutex_init(&rtc->char_lock);
+        spin_lock_init(&rtc->irq_lock);
+        init_waitqueue_head(&rtc->irq_queue);
+
+        cdev_init(&rtc->char_dev, &rtc_dev_fops);
+        rtc->char_dev.owner = rtc->owner;
+
+        if (cdev_add(&rtc->char_dev, MKDEV(MAJOR(rtc_devt), rtc->id), 1)) {
+                cdev_del(&rtc->char_dev);
+                dev_err(class_dev->dev,
+                        "failed to add char device %d:%d\n",
+                        MAJOR(rtc_devt), rtc->id);
+                return -ENODEV;
+        }
+
+        rtc->rtc_dev = class_device_create(rtc_dev_class, NULL,
+                                                MKDEV(MAJOR(rtc_devt), rtc->id),
+                                                class_dev->dev, "rtc%d", rtc->id);
+        if (IS_ERR(rtc->rtc_dev)) {
+                dev_err(class_dev->dev, "cannot create rtc_dev device\n");
+                err = PTR_ERR(rtc->rtc_dev);
+                goto err_cdev_del;
+        }
+
+        dev_info(class_dev->dev, "rtc intf: dev (%d:%d)\n",
+                MAJOR(rtc->rtc_dev->devt),
+                MINOR(rtc->rtc_dev->devt));
+
+        return 0;
+
+err_cdev_del:
+
+        cdev_del(&rtc->char_dev);
+        return err;
+}
+
+static void rtc_dev_remove_device(struct class_device *class_dev,
+                                        struct class_interface *class_intf)
+{
+        struct rtc_device *rtc = to_rtc_device(class_dev);
+
+        if (rtc->rtc_dev) {
+                dev_dbg(class_dev->dev, "removing char %d:%d\n",
+                        MAJOR(rtc->rtc_dev->devt),
+                        MINOR(rtc->rtc_dev->devt));
+
+                class_device_unregister(rtc->rtc_dev);
+                cdev_del(&rtc->char_dev);
+        }
+}
+
+/* interface registration */
+
+static struct class_interface rtc_dev_interface = {
+        .add = &rtc_dev_add_device,
+        .remove = &rtc_dev_remove_device,
+};
+
+static int __init rtc_dev_init(void)
+{
+        int err;
+
+        rtc_dev_class = class_create(THIS_MODULE, "rtc-dev");
+        if (IS_ERR(rtc_dev_class))
+                return PTR_ERR(rtc_dev_class);
+
+        err = alloc_chrdev_region(&rtc_devt, 0, RTC_DEV_MAX, "rtc");
+        if (err < 0) {
+                printk(KERN_ERR "%s: failed to allocate char dev region\n",
+                        __FILE__);
+                goto err_destroy_class;
+        }
+
+        err = rtc_interface_register(&rtc_dev_interface);
+        if (err < 0) {
+                printk(KERN_ERR "%s: failed to register the interface\n",
+                        __FILE__);
+                goto err_unregister_chrdev;
+        }
+
+        return 0;
+
+err_unregister_chrdev:
+        unregister_chrdev_region(rtc_devt, RTC_DEV_MAX);
+
+err_destroy_class:
+        class_destroy(rtc_dev_class);
+
+        return err;
+}
+
+static void __exit rtc_dev_exit(void)
+{
+        class_interface_unregister(&rtc_dev_interface);
+        class_destroy(rtc_dev_class);
+        unregister_chrdev_region(rtc_devt, RTC_DEV_MAX);
+}
+
+module_init(rtc_dev_init);
+module_exit(rtc_dev_exit);
+
+MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
+MODULE_DESCRIPTION("RTC class dev interface");
+MODULE_LICENSE("GPL");