diff options
| -rw-r--r-- | samples/Kconfig | 10 | ||||
| -rw-r--r-- | samples/Makefile | 2 | ||||
| -rw-r--r-- | samples/kobject/Makefile | 1 | ||||
| -rw-r--r-- | samples/kobject/kobject-example.c | 137 |
4 files changed, 149 insertions, 1 deletions
diff --git a/samples/Kconfig b/samples/Kconfig index 57bb223..74d97cc 100644 --- a/samples/Kconfig +++ b/samples/Kconfig @@ -13,4 +13,14 @@ config SAMPLE_MARKERS help This build markers example modules. +config SAMPLE_KOBJECT + tristate "Build kobject examples" + help + This config option will allow you to build a number of + different kobject sample modules showing how to use kobjects, + ksets, and ktypes properly. + + If in doubt, say "N" here. + endif # SAMPLES + diff --git a/samples/Makefile b/samples/Makefile index 5a4f0b6..8652d0f 100644 --- a/samples/Makefile +++ b/samples/Makefile @@ -1,3 +1,3 @@ # Makefile for Linux samples code -obj-$(CONFIG_SAMPLES) += markers/ +obj-$(CONFIG_SAMPLES) += markers/ kobject/ diff --git a/samples/kobject/Makefile b/samples/kobject/Makefile new file mode 100644 index 0000000..cce16e9 --- /dev/null +++ b/samples/kobject/Makefile @@ -0,0 +1 @@ +obj-$(CONFIG_SAMPLE_KOBJECT) += kobject-example.o diff --git a/samples/kobject/kobject-example.c b/samples/kobject/kobject-example.c new file mode 100644 index 0000000..08d0d3f --- /dev/null +++ b/samples/kobject/kobject-example.c @@ -0,0 +1,137 @@ +/* + * 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>"); |