[PATCH 18/22] [PATCH] Driver core: allow struct device to have a dev_t

Greg KH
2006-06-21T19:53:47Z

From: Greg Kroah-Hartman <gregkh@suse.de>

This is the first step in moving class_device to being replaced by
struct device. It allows struct device to export a dev_t and makes it
easy to dynamically create and destroy struct device as long as they are
associated with a specific class.

Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---
drivers/base/class.c | 1
drivers/base/core.c | 162 ++++++++++++++++++++++++++++++++++++++++++++++++
include/linux/device.h | 14 ++++
3 files changed, 176 insertions(+), 1 deletions(-)

diff --git a/drivers/base/class.c b/drivers/base/class.c
index 41a8e09..50e841a 100644
--- a/drivers/base/class.c
+++ b/drivers/base/class.c
@@ -142,6 +142,7 @@ int class_register(struct class * cls)
pr_debug("device class '%s': registering\n", cls->name);

INIT_LIST_HEAD(&cls->children);
+ INIT_LIST_HEAD(&cls->devices);
INIT_LIST_HEAD(&cls->interfaces);
init_MUTEX(&cls->sem);
error = kobject_set_name(&cls->subsys.kset.kobj, "%s", cls->name);
diff --git a/drivers/base/core.c b/drivers/base/core.c
index d5e15a0..252cf40 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -15,6 +15,7 @@ #include <linux/init.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/string.h>
+#include <linux/kdev_t.h>

#include <asm/semaphore.h>

@@ -98,6 +99,8 @@ static int dev_uevent_filter(struct kset
struct device *dev = to_dev(kobj);
if (dev->bus)
return 1;
+ if (dev->class)
+ return 1;
}
return 0;
}
@@ -106,7 +109,11 @@ static const char *dev_uevent_name(struc
{
struct device *dev = to_dev(kobj);

- return dev->bus->name;
+ if (dev->bus)
+ return dev->bus->name;
+ if (dev->class)
+ return dev->class->name;
+ return NULL;
}

static int dev_uevent(struct kset *kset, struct kobject *kobj, char **envp,
@@ -117,6 +124,16 @@ static int dev_uevent(struct kset *kset,
int length = 0;
int retval = 0;

+ /* add the major/minor if present */
+ if (MAJOR(dev->devt)) {
+ add_uevent_var(envp, num_envp, &i,
+ buffer, buffer_size, &length,
+ "MAJOR=%u", MAJOR(dev->devt));
+ add_uevent_var(envp, num_envp, &i,
+ buffer, buffer_size, &length,
+ "MINOR=%u", MINOR(dev->devt));
+ }
+
/* add bus name of physical device */
if (dev->bus)
add_uevent_var(envp, num_envp, &i,
@@ -161,6 +178,12 @@ static ssize_t store_uevent(struct devic
return count;
}

+static ssize_t show_dev(struct device *dev, struct device_attribute *attr,
+ char *buf)
+{
+ return print_dev_t(buf, dev->devt);
+}
+
/*
* devices_subsys - structure to be registered with kobject core.
*/
@@ -231,6 +254,7 @@ void device_initialize(struct device *de
klist_init(&dev->klist_children, klist_children_get,
klist_children_put);
INIT_LIST_HEAD(&dev->dma_pools);
+ INIT_LIST_HEAD(&dev->node);
init_MUTEX(&dev->sem);
device_init_wakeup(dev, 0);
}
@@ -274,6 +298,31 @@ int device_add(struct device *dev)
dev->uevent_attr.store = store_uevent;
device_create_file(dev, &dev->uevent_attr);

+ if (MAJOR(dev->devt)) {
+ struct device_attribute *attr;
+ attr = kzalloc(sizeof(*attr), GFP_KERNEL);
+ if (!attr) {
+ error = -ENOMEM;
+ goto PMError;
+ }
+ attr->attr.name = "dev";
+ attr->attr.mode = S_IRUGO;
+ if (dev->driver)
+ attr->attr.owner = dev->driver->owner;
+ attr->show = show_dev;
+ error = device_create_file(dev, attr);
+ if (error) {
+ kfree(attr);
+ goto attrError;
+ }
+
+ dev->devt_attr = attr;
+ }
+
+ if (dev->class)
+ sysfs_create_link(&dev->class->subsys.kset.kobj, &dev->kobj,
+ dev->bus_id);
+
if ((error = device_pm_add(dev)))
goto PMError;
if ((error = bus_add_device(dev)))
@@ -292,6 +341,11 @@ int device_add(struct device *dev)
BusError:
device_pm_remove(dev);
PMError:
+ if (dev->devt_attr) {
+ device_remove_file(dev, dev->devt_attr);
+ kfree(dev->devt_attr);
+ }
+ attrError:
kobject_uevent(&dev->kobj, KOBJ_REMOVE);
kobject_del(&dev->kobj);
Error:
@@ -366,6 +420,10 @@ void device_del(struct device * dev)

if (parent)
klist_del(&dev->knode_parent);
+ if (dev->devt_attr)
+ device_remove_file(dev, dev->devt_attr);
+ if (dev->class)
+ sysfs_remove_link(&dev->class->subsys.kset.kobj, dev->bus_id);
device_remove_file(dev, &dev->uevent_attr);

/* Notify the platform of the removal, in case they
@@ -450,3 +508,105 @@ EXPORT_SYMBOL_GPL(put_device);

EXPORT_SYMBOL_GPL(device_create_file);
EXPORT_SYMBOL_GPL(device_remove_file);
+
+
+static void device_create_release(struct device *dev)
+{
+ pr_debug("%s called for %s\n", __FUNCTION__, dev->bus_id);
+ kfree(dev);
+}
+
+/**
+ * device_create - creates a device and registers it with sysfs
+ * @cs: pointer to the struct class that this device should be registered to.
+ * @parent: pointer to the parent struct device of this new device, if any.
+ * @dev: the dev_t for the char device to be added.
+ * @fmt: string for the class device's name
+ *
+ * This function can be used by char device classes. A struct
+ * device will be created in sysfs, registered to the specified
+ * class.
+ * A "dev" file will be created, showing the dev_t for the device, if
+ * the dev_t is not 0,0.
+ * If a pointer to a parent struct device is passed in, the newly
+ * created struct device will be a child of that device in sysfs. The
+ * pointer to the struct device will be returned from the call. Any
+ * further sysfs files that might be required can be created using this
+ * pointer.
+ *
+ * Note: the struct class passed to this function must have previously
+ * been created with a call to class_create().
+ */
+struct device *device_create(struct class *class, struct device *parent,
+ dev_t devt, char *fmt, ...)
+{
+ va_list args;
+ struct device *dev = NULL;
+ int retval = -ENODEV;
+
+ if (class == NULL || IS_ERR(class))
+ goto error;
+ if (parent == NULL) {
+ printk(KERN_WARNING "%s does not work yet for NULL parents\n", __FUNCTION__);
+ goto error;
+ }
+
+ dev = kzalloc(sizeof(*dev), GFP_KERNEL);
+ if (!dev) {
+ retval = -ENOMEM;
+ goto error;
+ }
+
+ dev->devt = devt;
+ dev->class = class;
+ dev->parent = parent;
+ dev->release = device_create_release;
+
+ va_start(args, fmt);
+ vsnprintf(dev->bus_id, BUS_ID_SIZE, fmt, args);
+ va_end(args);
+ retval = device_register(dev);
+ if (retval)
+ goto error;
+
+ /* tie the class to the device */
+ down(&class->sem);
+ list_add_tail(&dev->node, &class->devices);
+ up(&class->sem);
+
+ return dev;
+
+error:
+ kfree(dev);
+ return ERR_PTR(retval);
+}
+EXPORT_SYMBOL_GPL(device_create);
+
+/**
+ * device_destroy - removes a device that was created with device_create()
+ * @class: the pointer to the struct class that this device was registered * with.
+ * @dev: the dev_t of the device that was previously registered.
+ *
+ * This call unregisters and cleans up a class device that was created with a
+ * call to class_device_create()
+ */
+void device_destroy(struct class *class, dev_t devt)
+{
+ struct device *dev = NULL;
+ struct device *dev_tmp;
+
+ down(&class->sem);
+ list_for_each_entry(dev_tmp, &class->devices, node) {
+ if (dev_tmp->devt == devt) {
+ dev = dev_tmp;
+ break;
+ }
+ }
+ up(&class->sem);
+
+ if (dev) {
+ list_del_init(&dev->node);
+ device_unregister(dev);
+ }
+}
+EXPORT_SYMBOL_GPL(device_destroy);
diff --git a/include/linux/device.h b/include/linux/device.h
index ade10dd..b473f42 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -142,6 +142,7 @@ struct class {

struct subsystem subsys;
struct list_head children;
+ struct list_head devices;
struct list_head interfaces;
struct semaphore sem; /* locks both the children and interfaces lists */

@@ -305,6 +306,7 @@ struct device {
struct kobject kobj;
char bus_id[BUS_ID_SIZE]; /* position on parent bus */
struct device_attribute uevent_attr;
+ struct device_attribute *devt_attr;

struct semaphore sem; /* semaphore to synchronize calls to
* its driver.
@@ -332,6 +334,11 @@ struct device {
struct dma_coherent_mem *dma_mem; /* internal for coherent mem
override */

+ /* class_device migration path */
+ struct list_head node;
+ struct class *class; /* optional*/
+ dev_t devt; /* dev_t, creates the sysfs "dev" */
+
void (*release)(struct device * dev);
};

@@ -373,6 +380,13 @@ extern int device_attach(struct device
extern void driver_attach(struct device_driver * drv);
extern void device_reprobe(struct device *dev);

+/*
+ * Easy functions for dynamically creating devices on the fly
+ */
+extern struct device *device_create(struct class *cls, struct device *parent,
+ dev_t devt, char *fmt, ...)
+ __attribute__((format(printf,4,5)));
+extern void device_destroy(struct class *cls, dev_t devt);

/*
* Platform "fixup" functions - allow the platform to have their say
--
1.4.0