drivers/dca/dca-sysfs.c

#include <linux/kernel.h>
#include <linux/spinlock.h>
#include <linux/device.h>
#include <linux/idr.h>
#include <linux/kdev_t.h>
#include <linux/err.h>
#include <linux/dca.h>

static struct class *dca_class;
static struct idr dca_idr;
static spinlock_t dca_idr_lock;

int dca_sysfs_add_req(struct dca_provider *dca, struct device *dev, int slot)
{
	struct device *cd;
	static int req_count;

	cd = device_create(dca_class, dca->cd, MKDEV(0, slot + 1),
			   "requester%d", req_count++);
	if (IS_ERR(cd))
		return PTR_ERR(cd);
	return 0;
}

void dca_sysfs_remove_req(struct dca_provider *dca, int slot)
{
	device_destroy(dca_class, MKDEV(0, slot + 1));
}

int dca_sysfs_add_provider(struct dca_provider *dca, struct device *dev)
{
	struct device *cd;
	int err = 0;

idr_try_again:
	if (!idr_pre_get(&dca_idr, GFP_KERNEL))
		return -ENOMEM;
	spin_lock(&dca_idr_lock);
	err = idr_get_new(&dca_idr, dca, &dca->id);
	spin_unlock(&dca_idr_lock);
	switch (err) {
	case 0:
		break;
	case -EAGAIN:
		goto idr_try_again;
	default:
		return err;
	}

	cd = device_create(dca_class, dev, MKDEV(0, 0), "dca%d", dca->id);
	if (IS_ERR(cd)) {
		spin_lock(&dca_idr_lock);
		idr_remove(&dca_idr, dca->id);
		spin_unlock(&dca_idr_lock);
		return PTR_ERR(cd);
	}
	dca->cd = cd;
	return 0;
}

void dca_sysfs_remove_provider(struct dca_provider *dca)
{
	device_unregister(dca->cd);
	dca->cd = NULL;
	spin_lock(&dca_idr_lock);
	idr_remove(&dca_idr, dca->id);
	spin_unlock(&dca_idr_lock);
}

int __init dca_sysfs_init(void)
{
	idr_init(&dca_idr);
	spin_lock_init(&dca_idr_lock);

	dca_class = class_create(THIS_MODULE, "dca");
	if (IS_ERR(dca_class)) {
		idr_destroy(&dca_idr);
		return PTR_ERR(dca_class);
	}
	return 0;
}

void __exit dca_sysfs_exit(void)
{
	class_destroy(dca_class);
	idr_destroy(&dca_idr);
}