[PATCH] RTC subsystem: sysfs interface

This patch adds the sysfs interface to the RTC subsystem.

Each RTC client will have his own entry under /sys/classs/rtc/rtcN .

Within this entry some attributes are exported by the subsystem, like date and
time.

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, 138 insertions, 0 deletions

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index a256f67b78e4..824499920485 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -40,6 +40,17 @@ config RTC_HCTOSYS_DEVICE
 comment "RTC interfaces"
         depends on RTC_CLASS
 
+config RTC_INTF_SYSFS
+        tristate "sysfs"
+        depends on RTC_CLASS && SYSFS
+        default RTC_CLASS
+        help
+          Say yes here if you want to use your RTC using the sysfs
+          interface, /sys/class/rtc/rtcX .
+
+          This driver can also be built as a module. If so, the module
+          will be called rtc-sysfs.
+
 comment "RTC drivers"
         depends on RTC_CLASS
 
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 7b87f3710dff..c44363355c2b 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -6,3 +6,6 @@ obj-$(CONFIG_RTC_LIB)		+= rtc-lib.o
 obj-$(CONFIG_RTC_HCTOSYS)       += hctosys.o
 obj-$(CONFIG_RTC_CLASS)         += rtc-core.o
 rtc-core-y                      := class.o interface.o
+
+obj-$(CONFIG_RTC_INTF_SYSFS)    += rtc-sysfs.o
+
diff --git a/drivers/rtc/rtc-sysfs.c b/drivers/rtc/rtc-sysfs.c
new file mode 100644
index 000000000000..7c1f3d2e53c4
--- /dev/null
+++ b/drivers/rtc/rtc-sysfs.c
@@ -0,0 +1,124 @@
+/*
+ * RTC subsystem, sysfs interface
+ *
+ * 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/module.h>
+#include <linux/rtc.h>
+
+/* device attributes */
+
+static ssize_t rtc_sysfs_show_name(struct class_device *dev, char *buf)
+{
+        return sprintf(buf, "%s\n", to_rtc_device(dev)->name);
+}
+static CLASS_DEVICE_ATTR(name, S_IRUGO, rtc_sysfs_show_name, NULL);
+
+static ssize_t rtc_sysfs_show_date(struct class_device *dev, char *buf)
+{
+        ssize_t retval;
+        struct rtc_time tm;
+
+        retval = rtc_read_time(dev, &tm);
+        if (retval == 0) {
+                retval = sprintf(buf, "%04d-%02d-%02d\n",
+                        tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday);
+        }
+
+        return retval;
+}
+static CLASS_DEVICE_ATTR(date, S_IRUGO, rtc_sysfs_show_date, NULL);
+
+static ssize_t rtc_sysfs_show_time(struct class_device *dev, char *buf)
+{
+        ssize_t retval;
+        struct rtc_time tm;
+
+        retval = rtc_read_time(dev, &tm);
+        if (retval == 0) {
+                retval = sprintf(buf, "%02d:%02d:%02d\n",
+                        tm.tm_hour, tm.tm_min, tm.tm_sec);
+        }
+
+        return retval;
+}
+static CLASS_DEVICE_ATTR(time, S_IRUGO, rtc_sysfs_show_time, NULL);
+
+static ssize_t rtc_sysfs_show_since_epoch(struct class_device *dev, char *buf)
+{
+        ssize_t retval;
+        struct rtc_time tm;
+
+        retval = rtc_read_time(dev, &tm);
+        if (retval == 0) {
+                unsigned long time;
+                rtc_tm_to_time(&tm, &time);
+                retval = sprintf(buf, "%lu\n", time);
+        }
+
+        return retval;
+}
+static CLASS_DEVICE_ATTR(since_epoch, S_IRUGO, rtc_sysfs_show_since_epoch, NULL);
+
+static struct attribute *rtc_attrs[] = {
+        &class_device_attr_name.attr,
+        &class_device_attr_date.attr,
+        &class_device_attr_time.attr,
+        &class_device_attr_since_epoch.attr,
+        NULL,
+};
+
+static struct attribute_group rtc_attr_group = {
+        .attrs = rtc_attrs,
+};
+
+static int __devinit rtc_sysfs_add_device(struct class_device *class_dev,
+                                        struct class_interface *class_intf)
+{
+        int err;
+
+        dev_info(class_dev->dev, "rtc intf: sysfs\n");
+
+        err = sysfs_create_group(&class_dev->kobj, &rtc_attr_group);
+        if (err)
+                dev_err(class_dev->dev,
+                        "failed to create sysfs attributes\n");
+
+        return err;
+}
+
+static void rtc_sysfs_remove_device(struct class_device *class_dev,
+                                struct class_interface *class_intf)
+{
+        sysfs_remove_group(&class_dev->kobj, &rtc_attr_group);
+}
+
+/* interface registration */
+
+static struct class_interface rtc_sysfs_interface = {
+        .add = &rtc_sysfs_add_device,
+        .remove = &rtc_sysfs_remove_device,
+};
+
+static int __init rtc_sysfs_init(void)
+{
+        return rtc_interface_register(&rtc_sysfs_interface);
+}
+
+static void __exit rtc_sysfs_exit(void)
+{
+        class_interface_unregister(&rtc_sysfs_interface);
+}
+
+module_init(rtc_sysfs_init);
+module_exit(rtc_sysfs_exit);
+
+MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
+MODULE_DESCRIPTION("RTC class sysfs interface");
+MODULE_LICENSE("GPL");