[PATCH 08/13] RTC subsystem, dev interface

Alessandro Zummo
2006-03-04T16:46:42Z

[-- Attachment #1: rtc-intf-dev.patch --]
[-- Type: text/plain, Size: 10517 bytes --]

This patch adds 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>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
--

drivers/rtc/Kconfig | 11 +
drivers/rtc/Makefile | 1
drivers/rtc/rtc-dev.c | 382 ++++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 394 insertions(+)

--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ linux-rtc/drivers/rtc/rtc-dev.c 2006-03-04 16:17:12.000000000 +0100
@@ -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 as published by
+ * the Free Software Foundation; version 2 of the License.
+*/
+
+#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");
--- linux-rtc.orig/drivers/rtc/Kconfig 2006-03-04 16:17:10.000000000 +0100
+++ linux-rtc/drivers/rtc/Kconfig 2006-03-04 16:17:12.000000000 +0100
@@ -61,6 +61,17 @@ 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

--- linux-rtc.orig/drivers/rtc/Makefile 2006-03-04 16:17:10.000000000 +0100
+++ linux-rtc/drivers/rtc/Makefile 2006-03-04 16:17:12.000000000 +0100
@@ -10,3 +10,4 @@ obj-$(CONFIG_RTC_CLASS) += rtc-core.o
rtc-core-y := class.o interface.o
obj-$(CONFIG_RTC_INTF_SYSFS) += rtc-sysfs.o
obj-$(CONFIG_RTC_INTF_PROC) += rtc-proc.o
+obj-$(CONFIG_RTC_INTF_DEV) += rtc-dev.o

--