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authorLinus Torvalds <torvalds@linux-foundation.org>2008-01-25 08:34:42 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2008-01-25 08:35:13 -0800
commitdf8dc74e8a383eaf2d9b44b80a71ec6f0e52b42e (patch)
treebc3799a43e8b94fa84b32e37b1c124d5e4868f50 /samples/kobject/kobject-example.c
parent556a169dab38b5100df6f4a45b655dddd3db94c1 (diff)
parent4a3ad20ccd8f4d2a0535cf98fa83f7b561ba59a9 (diff)
Merge git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-2.6
This can be broken down into these major areas: - Documentation updates (language translations and fixes, as well as kobject and kset documenatation updates.) - major kset/kobject/ktype rework and fixes. This cleans up the kset and kobject and ktype relationship and architecture, making sense of things now, and good documenation and samples are provided for others to use. Also the attributes for kobjects are much easier to handle now. This cleaned up a LOT of code all through the kernel, making kobjects easier to use if you want to. - struct bus_type has been reworked to now handle the lifetime rules properly, as the kobject is properly dynamic. - struct driver has also been reworked, and now the lifetime issues are resolved. - the block subsystem has been converted to use struct device now, and not "raw" kobjects. This patch has been in the -mm tree for over a year now, and finally all the issues are worked out with it. Older distros now properly work with new kernels, and no userspace updates are needed at all. - nozomi driver is added. This has also been in -mm for a long time, and many people have asked for it to go in. It is now in good enough shape to do so. - lots of class_device conversions to use struct device instead. The tree is almost all cleaned up now, only SCSI and IB is the remaining code to fix up... * git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-2.6: (196 commits) Driver core: coding style fixes Kobject: fix coding style issues in kobject c files Kobject: fix coding style issues in kobject.h Driver core: fix coding style issues in device.h spi: use class iteration api scsi: use class iteration api rtc: use class iteration api power supply : use class iteration api ieee1394: use class iteration api Driver Core: add class iteration api Driver core: Cleanup get_device_parent() in device_add() and device_move() UIO: constify function pointer tables Driver Core: constify the name passed to platform_device_register_simple driver core: fix build with SYSFS=n sysfs: make SYSFS_DEPRECATED depend on SYSFS Driver core: use LIST_HEAD instead of call to INIT_LIST_HEAD in __init kobject: add sample code for how to use ksets/ktypes/kobjects kobject: add sample code for how to use kobjects in a simple manner. kobject: update the kobject/kset documentation kobject: remove old, outdated documentation. ...
Diffstat (limited to 'samples/kobject/kobject-example.c')
-rw-r--r--samples/kobject/kobject-example.c137
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diff --git a/samples/kobject/kobject-example.c b/samples/kobject/kobject-example.c
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+++ b/samples/kobject/kobject-example.c
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+/*
+ * Sample kobject implementation
+ *
+ * Copyright (C) 2004-2007 Greg Kroah-Hartman <greg@kroah.com>
+ * Copyright (C) 2007 Novell Inc.
+ *
+ * Released under the GPL version 2 only.
+ *
+ */
+#include <linux/kobject.h>
+#include <linux/string.h>
+#include <linux/sysfs.h>
+#include <linux/module.h>
+#include <linux/init.h>
+
+/*
+ * This module shows how to create a simple subdirectory in sysfs called
+ * /sys/kernel/kobject-example In that directory, 3 files are created:
+ * "foo", "baz", and "bar". If an integer is written to these files, it can be
+ * later read out of it.
+ */
+
+static int foo;
+static int baz;
+static int bar;
+
+/*
+ * The "foo" file where a static variable is read from and written to.
+ */
+static ssize_t foo_show(struct kobject *kobj, struct kobj_attribute *attr,
+ char *buf)
+{
+ return sprintf(buf, "%d\n", foo);
+}
+
+static ssize_t foo_store(struct kobject *kobj, struct kobj_attribute *attr,
+ const char *buf, size_t count)
+{
+ sscanf(buf, "%du", &foo);
+ return count;
+}
+
+static struct kobj_attribute foo_attribute =
+ __ATTR(foo, 0666, foo_show, foo_store);
+
+/*
+ * More complex function where we determine which varible is being accessed by
+ * looking at the attribute for the "baz" and "bar" files.
+ */
+static ssize_t b_show(struct kobject *kobj, struct kobj_attribute *attr,
+ char *buf)
+{
+ int var;
+
+ if (strcmp(attr->attr.name, "baz") == 0)
+ var = baz;
+ else
+ var = bar;
+ return sprintf(buf, "%d\n", var);
+}
+
+static ssize_t b_store(struct kobject *kobj, struct kobj_attribute *attr,
+ const char *buf, size_t count)
+{
+ int var;
+
+ sscanf(buf, "%du", &var);
+ if (strcmp(attr->attr.name, "baz") == 0)
+ baz = var;
+ else
+ bar = var;
+ return count;
+}
+
+static struct kobj_attribute baz_attribute =
+ __ATTR(baz, 0666, b_show, b_store);
+static struct kobj_attribute bar_attribute =
+ __ATTR(bar, 0666, b_show, b_store);
+
+
+/*
+ * Create a group of attributes so that we can create and destory them all
+ * at once.
+ */
+static struct attribute *attrs[] = {
+ &foo_attribute.attr,
+ &baz_attribute.attr,
+ &bar_attribute.attr,
+ NULL, /* need to NULL terminate the list of attributes */
+};
+
+/*
+ * An unnamed attribute group will put all of the attributes directly in
+ * the kobject directory. If we specify a name, a subdirectory will be
+ * created for the attributes with the directory being the name of the
+ * attribute group.
+ */
+static struct attribute_group attr_group = {
+ .attrs = attrs,
+};
+
+static struct kobject *example_kobj;
+
+static int example_init(void)
+{
+ int retval;
+
+ /*
+ * Create a simple kobject with the name of "kobject_example",
+ * located under /sys/kernel/
+ *
+ * As this is a simple directory, no uevent will be sent to
+ * userspace. That is why this function should not be used for
+ * any type of dynamic kobjects, where the name and number are
+ * not known ahead of time.
+ */
+ example_kobj = kobject_create_and_add("kobject_example", kernel_kobj);
+ if (!example_kobj)
+ return -ENOMEM;
+
+ /* Create the files associated with this kobject */
+ retval = sysfs_create_group(example_kobj, &attr_group);
+ if (retval)
+ kobject_put(example_kobj);
+
+ return retval;
+}
+
+static void example_exit(void)
+{
+ kobject_put(example_kobj);
+}
+
+module_init(example_init);
+module_exit(example_exit);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Greg Kroah-Hartman <greg@kroah.com>");