#include <linux/init.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/types.h>
#include <linux/cdev.h>
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/semaphore.h>


#include "mod.h"
#include "dev.h"
#include "debug.h"
#include "sysfs.h"


MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Suren A. Chilingaryan <csa@suren.me>");
MODULE_DESCRIPTION("Testing module");
MODULE_VERSION("0.0.1");

int test_minors = TEST_MINORS;

module_param(test_minors, int, S_IRUGO);


static dev_t test_devno;			/**< major number */
static test_dev_t **test_devs = NULL;	        /**< per-device context */
static DEFINE_SEMAPHORE(test_devs_mtx);            /**< mutex protecting creation/destruction of devices */
static struct class *test_class;		/**< device class */

static void test_module_destroy_cdev(test_dev_t *test)
{
    if (test->dev) {
	test_sysfs_free(test);
	device_destroy(test_class, test->devno);
    }
    cdev_del(&test->cdev);
    kfree(test);
}

static int test_module_setup_cdev(void)
{
    int i;
    int err = 0;
    dev_t devno;
    test_dev_t *test;

    test = kmalloc(sizeof(test_dev_t), GFP_KERNEL);
    if (!test) {
	mod_info("Couldn't allocate memory. Device is not created.\n");
	return -ENOMEM;
    }

    cdev_init(&test->cdev, test_get_fops());
    test->cdev.owner = THIS_MODULE;
    test->cdev.ops = test_get_fops();

    down(&test_devs_mtx);
    for (i = 0; i < test_minors; i++) {
	if (!test_devs[i])
	    break;
    }

    if (i == test_minors) {
	mod_info("No free minor numbers left");
	err = -EBUSY;
	goto fail;
    }

    devno = MKDEV(MAJOR(test_devno), MINOR(test_devno) + i);
    test->devno = devno;

    err = cdev_add(&test->cdev, devno, 1);
    if (err) {
	mod_info("Error %d adding device kmm%d", err, i);
	goto fail;
    }

    test->dev = device_create(test_class, NULL, devno, test, TEST_NODE_FMT, MINOR(test_devno) + i);
    if (!test->dev) {
	mod_info("Error creating /dev/%s%d\n", TEST_NODE, MINOR(test_devno) + i);
	goto fail;
    }
    dev_set_drvdata(test->dev, test);

    test_devs[i] = test;
    up(&test_devs_mtx);

    err = test_sysfs_init(test);
    if (err) goto fail_sysfs;

    mod_info("Device /dev/%s%d added\n", TEST_NODE, MINOR(test_devno) + i);

    return 0;

fail:
    up(&test_devs_mtx);
fail_sysfs:
    test_module_destroy_cdev(test);
    return err;
}


static void test_module_cleanup(void)
{
    int i;

    if (test_devs) {
	for (i = 0; i < test_minors; i++) {
	    if (test_devs[i])
		test_module_destroy_cdev(test_devs[i]);
	}
	kfree(test_devs);
    }


    if (test_class)
    	class_destroy(test_class);

    unregister_chrdev_region(test_devno, test_minors);
}

static int __init test_module_init(void)
{
    int err;

    if ((err = alloc_chrdev_region(&test_devno, 0, test_minors, TEST_NODE))) {
	mod_info("Couldn't allocate chrdev region. Module not loaded.\n");
	goto alloc_chrdev_fail;
    }

    test_class = class_create(THIS_MODULE, TEST_NODE);
    if (IS_ERR(test_class)) {
	mod_info("No sysfs support. Module not loaded.\n");
	goto fail;
    }

    test_devs = kmalloc(test_minors * sizeof(test_dev_t*), GFP_KERNEL);
    if (!test_devs) {
	mod_info("Couldn't allocate memory. Module not loaded.\n");
	err = -ENOMEM;
    }
    memset(test_devs, 0, test_minors * sizeof(test_dev_t*));

    mod_info("Major %d allocated to node '%s'\n", MAJOR(test_devno), TEST_NODE);

    err = test_module_setup_cdev();
    if (err) goto fail;


    return 0;

fail:
    test_module_cleanup();
alloc_chrdev_fail:
    return err;
}


static void __exit test_module_exit(void)
{
    test_module_cleanup();
}

module_init(test_module_init);
module_exit(test_module_exit);