[linux-block.git] / drivers / char / bsr.c

/* IBM POWER Barrier Synchronization Register Driver
 *
 * Copyright IBM Corporation 2008
 *
 * Author: Sonny Rao <sonnyrao@us.ibm.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 */

#include <linux/kernel.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/of_platform.h>
#include <linux/module.h>
#include <linux/cdev.h>
#include <linux/list.h>
#include <linux/mm.h>
#include <asm/pgtable.h>
#include <asm/io.h>

/*
 This driver exposes a special register which can be used for fast
 synchronization across a large SMP machine.  The hardware is exposed
 as an array of bytes where each process will write to one of the bytes to
 indicate it has finished the current stage and this update is broadcast to
 all processors without having to bounce a cacheline between them. In
 POWER5 and POWER6 there is one of these registers per SMP,  but it is
 presented in two forms; first, it is given as a whole and then as a number
 of smaller registers which alias to parts of the single whole register.
 This can potentially allow multiple groups of processes to each have their
 own private synchronization device.

 Note that this hardware *must* be written to using *only* single byte writes.
 It may be read using 1, 2, 4, or 8 byte loads which must be aligned since
 this region is treated as cache-inhibited  processes should also use a
 full sync before and after writing to the BSR to ensure all stores and
 the BSR update have made it to all chips in the system
*/

/* This is arbitrary number, up to Power6 it's been 17 or fewer  */
#define BSR_MAX_DEVS (32)

struct bsr_dev {
	u64      bsr_addr;     /* Real address */
	u64      bsr_len;      /* length of mem region we can map */
	unsigned bsr_bytes;    /* size of the BSR reg itself */
	unsigned bsr_stride;   /* interval at which BSR repeats in the page */
	unsigned bsr_type;     /* maps to enum below */
	unsigned bsr_num;      /* bsr id number for its type */
	int      bsr_minor;

	struct list_head bsr_list;

	dev_t    bsr_dev;
	struct cdev bsr_cdev;
	struct device *bsr_device;
	char     bsr_name[32];

};

static unsigned total_bsr_devs;
static struct list_head bsr_devs = LIST_HEAD_INIT(bsr_devs);
static struct class *bsr_class;
static int bsr_major;

enum {
	BSR_8    = 0,
	BSR_16   = 1,
	BSR_64   = 2,
	BSR_128  = 3,
	BSR_4096 = 4,
	BSR_UNKNOWN = 5,
	BSR_MAX  = 6,
};

static unsigned bsr_types[BSR_MAX];

static ssize_t
bsr_size_show(struct device *dev, struct device_attribute *attr, char *buf)
{
	struct bsr_dev *bsr_dev = dev_get_drvdata(dev);
	return sprintf(buf, "%u\n", bsr_dev->bsr_bytes);
}

static ssize_t
bsr_stride_show(struct device *dev, struct device_attribute *attr, char *buf)
{
	struct bsr_dev *bsr_dev = dev_get_drvdata(dev);
	return sprintf(buf, "%u\n", bsr_dev->bsr_stride);
}

static ssize_t
bsr_len_show(struct device *dev, struct device_attribute *attr, char *buf)
{
	struct bsr_dev *bsr_dev = dev_get_drvdata(dev);
	return sprintf(buf, "%llu\n", bsr_dev->bsr_len);
}

static struct device_attribute bsr_dev_attrs[] = {
	__ATTR(bsr_size, S_IRUGO, bsr_size_show, NULL),
	__ATTR(bsr_stride, S_IRUGO, bsr_stride_show, NULL),
	__ATTR(bsr_length, S_IRUGO, bsr_len_show, NULL),
	__ATTR_NULL
};

static int bsr_mmap(struct file *filp, struct vm_area_struct *vma)
{
	unsigned long size   = vma->vm_end - vma->vm_start;
	struct bsr_dev *dev = filp->private_data;
	int ret;

	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);

	/* check for the case of a small BSR device and map one 4k page for it*/
	if (dev->bsr_len < PAGE_SIZE && size == PAGE_SIZE)
		ret = remap_4k_pfn(vma, vma->vm_start, dev->bsr_addr >> 12,
				   vma->vm_page_prot);
	else if (size <= dev->bsr_len)
		ret = io_remap_pfn_range(vma, vma->vm_start,
					 dev->bsr_addr >> PAGE_SHIFT,
					 size, vma->vm_page_prot);
	else
		return -EINVAL;

	if (ret)
		return -EAGAIN;

	return 0;
}

static int bsr_open(struct inode * inode, struct file * filp)
{
	struct cdev *cdev = inode->i_cdev;
	struct bsr_dev *dev = container_of(cdev, struct bsr_dev, bsr_cdev);

	filp->private_data = dev;
	return 0;
}

static const struct file_operations bsr_fops = {
	.owner = THIS_MODULE,
	.mmap  = bsr_mmap,
	.open  = bsr_open,
};

static void bsr_cleanup_devs(void)
{
	struct bsr_dev *cur, *n;

	list_for_each_entry_safe(cur, n, &bsr_devs, bsr_list) {
		if (cur->bsr_device) {
			cdev_del(&cur->bsr_cdev);
			device_del(cur->bsr_device);
		}
		list_del(&cur->bsr_list);
		kfree(cur);
	}
}

static int bsr_add_node(struct device_node *bn)
{
	int bsr_stride_len, bsr_bytes_len, num_bsr_devs;
	const u32 *bsr_stride;
	const u32 *bsr_bytes;
	unsigned i;
	int ret = -ENODEV;

	bsr_stride = of_get_property(bn, "ibm,lock-stride", &bsr_stride_len);
	bsr_bytes  = of_get_property(bn, "ibm,#lock-bytes", &bsr_bytes_len);

	if (!bsr_stride || !bsr_bytes ||
	    (bsr_stride_len != bsr_bytes_len)) {
		printk(KERN_ERR "bsr of-node has missing/incorrect property\n");
		return ret;
	}

	num_bsr_devs = bsr_bytes_len / sizeof(u32);

	for (i = 0 ; i < num_bsr_devs; i++) {
		struct bsr_dev *cur = kzalloc(sizeof(struct bsr_dev),
					      GFP_KERNEL);
		struct resource res;
		int result;

		if (!cur) {
			printk(KERN_ERR "Unable to alloc bsr dev\n");
			ret = -ENOMEM;
			goto out_err;
		}

		result = of_address_to_resource(bn, i, &res);
		if (result < 0) {
			printk(KERN_ERR "bsr of-node has invalid reg property, skipping\n");
			kfree(cur);
			continue;
		}

		cur->bsr_minor  = i + total_bsr_devs;
		cur->bsr_addr   = res.start;
		cur->bsr_len    = res.end - res.start + 1;
		cur->bsr_bytes  = bsr_bytes[i];
		cur->bsr_stride = bsr_stride[i];
		cur->bsr_dev    = MKDEV(bsr_major, i + total_bsr_devs);

		/* if we have a bsr_len of > 4k and less then PAGE_SIZE (64k pages) */
		/* we can only map 4k of it, so only advertise the 4k in sysfs */
		if (cur->bsr_len > 4096 && cur->bsr_len < PAGE_SIZE)
			cur->bsr_len = 4096;

		switch(cur->bsr_bytes) {
		case 8:
			cur->bsr_type = BSR_8;
			break;
		case 16:
			cur->bsr_type = BSR_16;
			break;
		case 64:
			cur->bsr_type = BSR_64;
			break;
		case 128:
			cur->bsr_type = BSR_128;
			break;
		case 4096:
			cur->bsr_type = BSR_4096;
			break;
		default:
			cur->bsr_type = BSR_UNKNOWN;
		}

		cur->bsr_num = bsr_types[cur->bsr_type];
		snprintf(cur->bsr_name, 32, "bsr%d_%d",
			 cur->bsr_bytes, cur->bsr_num);

		cdev_init(&cur->bsr_cdev, &bsr_fops);
		result = cdev_add(&cur->bsr_cdev, cur->bsr_dev, 1);
		if (result) {
			kfree(cur);
			goto out_err;
		}

		cur->bsr_device = device_create(bsr_class, NULL, cur->bsr_dev,
						cur, cur->bsr_name);
		if (!cur->bsr_device) {
			printk(KERN_ERR "device_create failed for %s\n",
			       cur->bsr_name);
			cdev_del(&cur->bsr_cdev);
			kfree(cur);
			goto out_err;
		}

		bsr_types[cur->bsr_type] = cur->bsr_num + 1;
		list_add_tail(&cur->bsr_list, &bsr_devs);
	}

	total_bsr_devs += num_bsr_devs;

	return 0;

 out_err:

	bsr_cleanup_devs();
	return ret;
}

static int bsr_create_devs(struct device_node *bn)
{
	int ret;

	while (bn) {
		ret = bsr_add_node(bn);
		if (ret) {
			of_node_put(bn);
			return ret;
		}
		bn = of_find_compatible_node(bn, NULL, "ibm,bsr");
	}
	return 0;
}

static int __init bsr_init(void)
{
	struct device_node *np;
	dev_t bsr_dev = MKDEV(bsr_major, 0);
	int ret = -ENODEV;
	int result;

	np = of_find_compatible_node(NULL, NULL, "ibm,bsr");
	if (!np)
		goto out_err;

	bsr_class = class_create(THIS_MODULE, "bsr");
	if (IS_ERR(bsr_class)) {
		printk(KERN_ERR "class_create() failed for bsr_class\n");
		goto out_err_1;
	}
	bsr_class->dev_attrs = bsr_dev_attrs;

	result = alloc_chrdev_region(&bsr_dev, 0, BSR_MAX_DEVS, "bsr");
	bsr_major = MAJOR(bsr_dev);
	if (result < 0) {
		printk(KERN_ERR "alloc_chrdev_region() failed for bsr\n");
		goto out_err_2;
	}

	if ((ret = bsr_create_devs(np)) < 0) {
		np = NULL;
		goto out_err_3;
	}

	return 0;

 out_err_3:
	unregister_chrdev_region(bsr_dev, BSR_MAX_DEVS);

 out_err_2:
	class_destroy(bsr_class);

 out_err_1:
	of_node_put(np);

 out_err:

	return ret;
}

static void __exit  bsr_exit(void)
{

	bsr_cleanup_devs();

	if (bsr_class)
		class_destroy(bsr_class);

	if (bsr_major)
		unregister_chrdev_region(MKDEV(bsr_major, 0), BSR_MAX_DEVS);
}

module_init(bsr_init);
module_exit(bsr_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Sonny Rao <sonnyrao@us.ibm.com>");
Commit	Line	Data
fe9e8d53 SR	1	/* IBM POWER Barrier Synchronization Register Driver
	2	*
	3	* Copyright IBM Corporation 2008
	4	*
	5	* Author: Sonny Rao <sonnyrao@us.ibm.com>
	6	*
	7	* This program is free software; you can redistribute it and/or modify
	8	* it under the terms of the GNU General Public License as published by
	9	* the Free Software Foundation; either version 2 of the License, or
	10	* (at your option) any later version.
	11	*
	12	* This program is distributed in the hope that it will be useful,
	13	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	14	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	15	* GNU General Public License for more details.
	16	*
	17	* You should have received a copy of the GNU General Public License
	18	* along with this program; if not, write to the Free Software
	19	* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
	20	*/
	21
	22	#include <linux/kernel.h>
	23	#include <linux/of.h>
	24	#include <linux/of_device.h>
	25	#include <linux/of_platform.h>
	26	#include <linux/module.h>
	27	#include <linux/cdev.h>
	28	#include <linux/list.h>
	29	#include <linux/mm.h>
04a85d12	30	#include <asm/pgtable.h>
fe9e8d53 SR	31	#include <asm/io.h>
	32
	33	/*
	34	This driver exposes a special register which can be used for fast
	35	synchronization across a large SMP machine. The hardware is exposed
	36	as an array of bytes where each process will write to one of the bytes to
	37	indicate it has finished the current stage and this update is broadcast to
	38	all processors without having to bounce a cacheline between them. In
	39	POWER5 and POWER6 there is one of these registers per SMP, but it is
	40	presented in two forms; first, it is given as a whole and then as a number
	41	of smaller registers which alias to parts of the single whole register.
	42	This can potentially allow multiple groups of processes to each have their
	43	own private synchronization device.
	44
	45	Note that this hardware must be written to using only single byte writes.
	46	It may be read using 1, 2, 4, or 8 byte loads which must be aligned since
	47	this region is treated as cache-inhibited processes should also use a
	48	full sync before and after writing to the BSR to ensure all stores and
	49	the BSR update have made it to all chips in the system
	50	*/
	51
	52	/* This is arbitrary number, up to Power6 it's been 17 or fewer */
	53	#define BSR_MAX_DEVS (32)
	54
	55	struct bsr_dev {
	56	u64 bsr_addr; /* Real address */
	57	u64 bsr_len; /* length of mem region we can map */
	58	unsigned bsr_bytes; /* size of the BSR reg itself */
	59	unsigned bsr_stride; /* interval at which BSR repeats in the page */
	60	unsigned bsr_type; /* maps to enum below */
	61	unsigned bsr_num; /* bsr id number for its type */
	62	int bsr_minor;
	63
a0e2f9f4 SR	64	struct list_head bsr_list;
a0e2f9f4 SR	65
fe9e8d53 SR	66	dev_t bsr_dev;
	67	struct cdev bsr_cdev;
	68	struct device *bsr_device;
	69	char bsr_name[32];
	70
	71	};
	72
a0e2f9f4 SR	73	static unsigned total_bsr_devs;
a0e2f9f4 SR	74	static struct list_head bsr_devs = LIST_HEAD_INIT(bsr_devs);
fe9e8d53 SR	75	static struct class *bsr_class;
	76	static int bsr_major;
	77
	78	enum {
e4031d52 SR	79	BSR_8 = 0,
	80	BSR_16 = 1,
	81	BSR_64 = 2,
	82	BSR_128 = 3,
	83	BSR_4096 = 4,
	84	BSR_UNKNOWN = 5,
	85	BSR_MAX = 6,
fe9e8d53 SR	86	};
	87
	88	static unsigned bsr_types[BSR_MAX];
	89
	90	static ssize_t
	91	bsr_size_show(struct device dev, struct device_attribute attr, char *buf)
	92	{
	93	struct bsr_dev *bsr_dev = dev_get_drvdata(dev);
	94	return sprintf(buf, "%u\n", bsr_dev->bsr_bytes);
	95	}
	96
	97	static ssize_t
	98	bsr_stride_show(struct device dev, struct device_attribute attr, char *buf)
	99	{
	100	struct bsr_dev *bsr_dev = dev_get_drvdata(dev);
	101	return sprintf(buf, "%u\n", bsr_dev->bsr_stride);
	102	}
	103
	104	static ssize_t
	105	bsr_len_show(struct device dev, struct device_attribute attr, char *buf)
	106	{
	107	struct bsr_dev *bsr_dev = dev_get_drvdata(dev);
1901515c	108	return sprintf(buf, "%llu\n", bsr_dev->bsr_len);
fe9e8d53 SR	109	}
	110
	111	static struct device_attribute bsr_dev_attrs[] = {
	112	__ATTR(bsr_size, S_IRUGO, bsr_size_show, NULL),
	113	__ATTR(bsr_stride, S_IRUGO, bsr_stride_show, NULL),
	114	__ATTR(bsr_length, S_IRUGO, bsr_len_show, NULL),
	115	__ATTR_NULL
	116	};
	117
	118	static int bsr_mmap(struct file filp, struct vm_area_struct vma)
	119	{
	120	unsigned long size = vma->vm_end - vma->vm_start;
	121	struct bsr_dev *dev = filp->private_data;
04a85d12	122	int ret;
fe9e8d53	123
fe9e8d53 SR	124	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
fe9e8d53 SR	125
04a85d12 SR	126	/* check for the case of a small BSR device and map one 4k page for it*/
	127	if (dev->bsr_len < PAGE_SIZE && size == PAGE_SIZE)
	128	ret = remap_4k_pfn(vma, vma->vm_start, dev->bsr_addr >> 12,
	129	vma->vm_page_prot);
	130	else if (size <= dev->bsr_len)
	131	ret = io_remap_pfn_range(vma, vma->vm_start,
	132	dev->bsr_addr >> PAGE_SHIFT,
	133	size, vma->vm_page_prot);
	134	else
	135	return -EINVAL;
	136
	137	if (ret)
fe9e8d53 SR	138	return -EAGAIN;
	139
	140	return 0;
	141	}
	142
	143	static int bsr_open(struct inode * inode, struct file * filp)
	144	{
	145	struct cdev *cdev = inode->i_cdev;
	146	struct bsr_dev *dev = container_of(cdev, struct bsr_dev, bsr_cdev);
	147
	148	filp->private_data = dev;
	149	return 0;
	150	}
	151
27157a70	152	static const struct file_operations bsr_fops = {
fe9e8d53 SR	153	.owner = THIS_MODULE,
	154	.mmap = bsr_mmap,
	155	.open = bsr_open,
	156	};
	157
	158	static void bsr_cleanup_devs(void)
	159	{
a0e2f9f4 SR	160	struct bsr_dev cur, n;
	161
	162	list_for_each_entry_safe(cur, n, &bsr_devs, bsr_list) {
fe9e8d53 SR	163	if (cur->bsr_device) {
	164	cdev_del(&cur->bsr_cdev);
	165	device_del(cur->bsr_device);
	166	}
a0e2f9f4 SR	167	list_del(&cur->bsr_list);
a0e2f9f4 SR	168	kfree(cur);
fe9e8d53	169	}
fe9e8d53 SR	170	}
fe9e8d53 SR	171
a0e2f9f4	172	static int bsr_add_node(struct device_node *bn)
fe9e8d53	173	{
a0e2f9f4	174	int bsr_stride_len, bsr_bytes_len, num_bsr_devs;
fe9e8d53 SR	175	const u32 *bsr_stride;
	176	const u32 *bsr_bytes;
	177	unsigned i;
a0e2f9f4	178	int ret = -ENODEV;
fe9e8d53 SR	179
	180	bsr_stride = of_get_property(bn, "ibm,lock-stride", &bsr_stride_len);
	181	bsr_bytes = of_get_property(bn, "ibm,#lock-bytes", &bsr_bytes_len);
	182
	183	if (!bsr_stride \|\| !bsr_bytes \|\|
	184	(bsr_stride_len != bsr_bytes_len)) {
	185	printk(KERN_ERR "bsr of-node has missing/incorrect property\n");
a0e2f9f4	186	return ret;
fe9e8d53 SR	187	}
	188
	189	num_bsr_devs = bsr_bytes_len / sizeof(u32);
	190
fe9e8d53	191	for (i = 0 ; i < num_bsr_devs; i++) {
a0e2f9f4 SR	192	struct bsr_dev *cur = kzalloc(sizeof(struct bsr_dev),
a0e2f9f4 SR	193	GFP_KERNEL);
fe9e8d53 SR	194	struct resource res;
	195	int result;
	196
a0e2f9f4 SR	197	if (!cur) {
	198	printk(KERN_ERR "Unable to alloc bsr dev\n");
	199	ret = -ENOMEM;
	200	goto out_err;
	201	}
	202
fe9e8d53 SR	203	result = of_address_to_resource(bn, i, &res);
fe9e8d53 SR	204	if (result < 0) {
a0e2f9f4 SR	205	printk(KERN_ERR "bsr of-node has invalid reg property, skipping\n");
	206	kfree(cur);
	207	continue;
fe9e8d53 SR	208	}
fe9e8d53 SR	209
a0e2f9f4	210	cur->bsr_minor = i + total_bsr_devs;
fe9e8d53 SR	211	cur->bsr_addr = res.start;
	212	cur->bsr_len = res.end - res.start + 1;
	213	cur->bsr_bytes = bsr_bytes[i];
	214	cur->bsr_stride = bsr_stride[i];
a0e2f9f4	215	cur->bsr_dev = MKDEV(bsr_major, i + total_bsr_devs);
fe9e8d53	216
04a85d12 SR	217	/* if we have a bsr_len of > 4k and less then PAGE_SIZE (64k pages) */
	218	/* we can only map 4k of it, so only advertise the 4k in sysfs */
	219	if (cur->bsr_len > 4096 && cur->bsr_len < PAGE_SIZE)
	220	cur->bsr_len = 4096;
	221
fe9e8d53 SR	222	switch(cur->bsr_bytes) {
	223	case 8:
	224	cur->bsr_type = BSR_8;
	225	break;
	226	case 16:
	227	cur->bsr_type = BSR_16;
	228	break;
	229	case 64:
	230	cur->bsr_type = BSR_64;
	231	break;
	232	case 128:
	233	cur->bsr_type = BSR_128;
	234	break;
e4031d52 SR	235	case 4096:
	236	cur->bsr_type = BSR_4096;
	237	break;
fe9e8d53 SR	238	default:
fe9e8d53 SR	239	cur->bsr_type = BSR_UNKNOWN;
fe9e8d53 SR	240	}
	241
	242	cur->bsr_num = bsr_types[cur->bsr_type];
fe9e8d53 SR	243	snprintf(cur->bsr_name, 32, "bsr%d_%d",
	244	cur->bsr_bytes, cur->bsr_num);
	245
	246	cdev_init(&cur->bsr_cdev, &bsr_fops);
	247	result = cdev_add(&cur->bsr_cdev, cur->bsr_dev, 1);
a0e2f9f4 SR	248	if (result) {
a0e2f9f4 SR	249	kfree(cur);
fe9e8d53	250	goto out_err;
a0e2f9f4	251	}
fe9e8d53	252
03457cd4 GKH	253	cur->bsr_device = device_create(bsr_class, NULL, cur->bsr_dev,
03457cd4 GKH	254	cur, cur->bsr_name);
fe9e8d53 SR	255	if (!cur->bsr_device) {
	256	printk(KERN_ERR "device_create failed for %s\n",
	257	cur->bsr_name);
	258	cdev_del(&cur->bsr_cdev);
a0e2f9f4	259	kfree(cur);
fe9e8d53 SR	260	goto out_err;
fe9e8d53 SR	261	}
a0e2f9f4 SR	262
	263	bsr_types[cur->bsr_type] = cur->bsr_num + 1;
	264	list_add_tail(&cur->bsr_list, &bsr_devs);
fe9e8d53 SR	265	}
fe9e8d53 SR	266
a0e2f9f4 SR	267	total_bsr_devs += num_bsr_devs;
a0e2f9f4 SR	268
fe9e8d53 SR	269	return 0;
	270
	271	out_err:
	272
	273	bsr_cleanup_devs();
a0e2f9f4 SR	274	return ret;
	275	}
	276
	277	static int bsr_create_devs(struct device_node *bn)
	278	{
	279	int ret;
	280
	281	while (bn) {
	282	ret = bsr_add_node(bn);
	283	if (ret) {
	284	of_node_put(bn);
	285	return ret;
	286	}
	287	bn = of_find_compatible_node(bn, NULL, "ibm,bsr");
	288	}
	289	return 0;
fe9e8d53 SR	290	}
	291
	292	static int __init bsr_init(void)
	293	{
	294	struct device_node *np;
	295	dev_t bsr_dev = MKDEV(bsr_major, 0);
	296	int ret = -ENODEV;
	297	int result;
	298
a0e2f9f4	299	np = of_find_compatible_node(NULL, NULL, "ibm,bsr");
fe9e8d53 SR	300	if (!np)
	301	goto out_err;
	302
	303	bsr_class = class_create(THIS_MODULE, "bsr");
	304	if (IS_ERR(bsr_class)) {
	305	printk(KERN_ERR "class_create() failed for bsr_class\n");
	306	goto out_err_1;
	307	}
	308	bsr_class->dev_attrs = bsr_dev_attrs;
	309
	310	result = alloc_chrdev_region(&bsr_dev, 0, BSR_MAX_DEVS, "bsr");
	311	bsr_major = MAJOR(bsr_dev);
	312	if (result < 0) {
	313	printk(KERN_ERR "alloc_chrdev_region() failed for bsr\n");
	314	goto out_err_2;
	315	}
	316
a0e2f9f4 SR	317	if ((ret = bsr_create_devs(np)) < 0) {
a0e2f9f4 SR	318	np = NULL;
fe9e8d53	319	goto out_err_3;
a0e2f9f4	320	}
fe9e8d53 SR	321
	322	return 0;
	323
	324	out_err_3:
	325	unregister_chrdev_region(bsr_dev, BSR_MAX_DEVS);
	326
	327	out_err_2:
	328	class_destroy(bsr_class);
	329
	330	out_err_1:
	331	of_node_put(np);
	332
	333	out_err:
	334
	335	return ret;
	336	}
	337
	338	static void __exit bsr_exit(void)
	339	{
	340
	341	bsr_cleanup_devs();
	342
	343	if (bsr_class)
	344	class_destroy(bsr_class);
	345
	346	if (bsr_major)
	347	unregister_chrdev_region(MKDEV(bsr_major, 0), BSR_MAX_DEVS);
	348	}
	349
	350	module_init(bsr_init);
	351	module_exit(bsr_exit);
	352	MODULE_LICENSE("GPL");
	353	MODULE_AUTHOR("Sonny Rao <sonnyrao@us.ibm.com>");