[deliverable/linux.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/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_UNKNOWN = 4,
	BSR_MAX = 5,
};

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;

	if (size > dev->bsr_len || (size & (PAGE_SIZE-1)))
		return -EINVAL;

	vma->vm_flags |= (VM_IO | VM_DONTEXPAND);
	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);

	if (io_remap_pfn_range(vma, vma->vm_start, dev->bsr_addr >> PAGE_SHIFT,
			       size, vma->vm_page_prot))
		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;
}

const static 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);

		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;
		default:
			cur->bsr_type = BSR_UNKNOWN;
			printk(KERN_INFO "unknown BSR size %d\n",cur->bsr_bytes);
		}

		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>
	30	#include <asm/io.h>
	31
	32	/*
	33	This driver exposes a special register which can be used for fast
	34	synchronization across a large SMP machine. The hardware is exposed
	35	as an array of bytes where each process will write to one of the bytes to
	36	indicate it has finished the current stage and this update is broadcast to
	37	all processors without having to bounce a cacheline between them. In
	38	POWER5 and POWER6 there is one of these registers per SMP, but it is
	39	presented in two forms; first, it is given as a whole and then as a number
	40	of smaller registers which alias to parts of the single whole register.
	41	This can potentially allow multiple groups of processes to each have their
	42	own private synchronization device.
	43
	44	Note that this hardware must be written to using only single byte writes.
	45	It may be read using 1, 2, 4, or 8 byte loads which must be aligned since
	46	this region is treated as cache-inhibited processes should also use a
	47	full sync before and after writing to the BSR to ensure all stores and
	48	the BSR update have made it to all chips in the system
	49	*/
	50
	51	/* This is arbitrary number, up to Power6 it's been 17 or fewer */
	52	#define BSR_MAX_DEVS (32)
	53
	54	struct bsr_dev {
	55	u64 bsr_addr; /* Real address */
	56	u64 bsr_len; /* length of mem region we can map */
	57	unsigned bsr_bytes; /* size of the BSR reg itself */
	58	unsigned bsr_stride; /* interval at which BSR repeats in the page */
	59	unsigned bsr_type; /* maps to enum below */
	60	unsigned bsr_num; /* bsr id number for its type */
	61	int bsr_minor;
	62
a0e2f9f4 SR	63	struct list_head bsr_list;
a0e2f9f4 SR	64
fe9e8d53 SR	65	dev_t bsr_dev;
	66	struct cdev bsr_cdev;
	67	struct device *bsr_device;
	68	char bsr_name[32];
	69
	70	};
	71
a0e2f9f4 SR	72	static unsigned total_bsr_devs;
a0e2f9f4 SR	73	static struct list_head bsr_devs = LIST_HEAD_INIT(bsr_devs);
fe9e8d53 SR	74	static struct class *bsr_class;
	75	static int bsr_major;
	76
	77	enum {
	78	BSR_8 = 0,
	79	BSR_16 = 1,
	80	BSR_64 = 2,
	81	BSR_128 = 3,
	82	BSR_UNKNOWN = 4,
	83	BSR_MAX = 5,
	84	};
	85
	86	static unsigned bsr_types[BSR_MAX];
	87
	88	static ssize_t
	89	bsr_size_show(struct device dev, struct device_attribute attr, char *buf)
	90	{
	91	struct bsr_dev *bsr_dev = dev_get_drvdata(dev);
	92	return sprintf(buf, "%u\n", bsr_dev->bsr_bytes);
	93	}
	94
	95	static ssize_t
	96	bsr_stride_show(struct device dev, struct device_attribute attr, char *buf)
	97	{
	98	struct bsr_dev *bsr_dev = dev_get_drvdata(dev);
	99	return sprintf(buf, "%u\n", bsr_dev->bsr_stride);
	100	}
	101
	102	static ssize_t
	103	bsr_len_show(struct device dev, struct device_attribute attr, char *buf)
	104	{
	105	struct bsr_dev *bsr_dev = dev_get_drvdata(dev);
1901515c	106	return sprintf(buf, "%llu\n", bsr_dev->bsr_len);
fe9e8d53 SR	107	}
	108
	109	static struct device_attribute bsr_dev_attrs[] = {
	110	__ATTR(bsr_size, S_IRUGO, bsr_size_show, NULL),
	111	__ATTR(bsr_stride, S_IRUGO, bsr_stride_show, NULL),
	112	__ATTR(bsr_length, S_IRUGO, bsr_len_show, NULL),
	113	__ATTR_NULL
	114	};
	115
	116	static int bsr_mmap(struct file filp, struct vm_area_struct vma)
	117	{
	118	unsigned long size = vma->vm_end - vma->vm_start;
	119	struct bsr_dev *dev = filp->private_data;
	120
	121	if (size > dev->bsr_len \|\| (size & (PAGE_SIZE-1)))
	122	return -EINVAL;
	123
	124	vma->vm_flags \|= (VM_IO \| VM_DONTEXPAND);
	125	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
	126
	127	if (io_remap_pfn_range(vma, vma->vm_start, dev->bsr_addr >> PAGE_SHIFT,
	128	size, vma->vm_page_prot))
	129	return -EAGAIN;
	130
	131	return 0;
	132	}
	133
	134	static int bsr_open(struct inode * inode, struct file * filp)
	135	{
	136	struct cdev *cdev = inode->i_cdev;
	137	struct bsr_dev *dev = container_of(cdev, struct bsr_dev, bsr_cdev);
	138
	139	filp->private_data = dev;
	140	return 0;
	141	}
	142
	143	const static struct file_operations bsr_fops = {
	144	.owner = THIS_MODULE,
	145	.mmap = bsr_mmap,
	146	.open = bsr_open,
	147	};
	148
	149	static void bsr_cleanup_devs(void)
	150	{
a0e2f9f4 SR	151	struct bsr_dev cur, n;
	152
	153	list_for_each_entry_safe(cur, n, &bsr_devs, bsr_list) {
fe9e8d53 SR	154	if (cur->bsr_device) {
	155	cdev_del(&cur->bsr_cdev);
	156	device_del(cur->bsr_device);
	157	}
a0e2f9f4 SR	158	list_del(&cur->bsr_list);
a0e2f9f4 SR	159	kfree(cur);
fe9e8d53	160	}
fe9e8d53 SR	161	}
fe9e8d53 SR	162
a0e2f9f4	163	static int bsr_add_node(struct device_node *bn)
fe9e8d53	164	{
a0e2f9f4	165	int bsr_stride_len, bsr_bytes_len, num_bsr_devs;
fe9e8d53 SR	166	const u32 *bsr_stride;
	167	const u32 *bsr_bytes;
	168	unsigned i;
a0e2f9f4	169	int ret = -ENODEV;
fe9e8d53 SR	170
	171	bsr_stride = of_get_property(bn, "ibm,lock-stride", &bsr_stride_len);
	172	bsr_bytes = of_get_property(bn, "ibm,#lock-bytes", &bsr_bytes_len);
	173
	174	if (!bsr_stride \|\| !bsr_bytes \|\|
	175	(bsr_stride_len != bsr_bytes_len)) {
	176	printk(KERN_ERR "bsr of-node has missing/incorrect property\n");
a0e2f9f4	177	return ret;
fe9e8d53 SR	178	}
	179
	180	num_bsr_devs = bsr_bytes_len / sizeof(u32);
	181
fe9e8d53	182	for (i = 0 ; i < num_bsr_devs; i++) {
a0e2f9f4 SR	183	struct bsr_dev *cur = kzalloc(sizeof(struct bsr_dev),
a0e2f9f4 SR	184	GFP_KERNEL);
fe9e8d53 SR	185	struct resource res;
	186	int result;
	187
a0e2f9f4 SR	188	if (!cur) {
	189	printk(KERN_ERR "Unable to alloc bsr dev\n");
	190	ret = -ENOMEM;
	191	goto out_err;
	192	}
	193
fe9e8d53 SR	194	result = of_address_to_resource(bn, i, &res);
fe9e8d53 SR	195	if (result < 0) {
a0e2f9f4 SR	196	printk(KERN_ERR "bsr of-node has invalid reg property, skipping\n");
	197	kfree(cur);
	198	continue;
fe9e8d53 SR	199	}
fe9e8d53 SR	200
a0e2f9f4	201	cur->bsr_minor = i + total_bsr_devs;
fe9e8d53 SR	202	cur->bsr_addr = res.start;
	203	cur->bsr_len = res.end - res.start + 1;
	204	cur->bsr_bytes = bsr_bytes[i];
	205	cur->bsr_stride = bsr_stride[i];
a0e2f9f4	206	cur->bsr_dev = MKDEV(bsr_major, i + total_bsr_devs);
fe9e8d53 SR	207
	208	switch(cur->bsr_bytes) {
	209	case 8:
	210	cur->bsr_type = BSR_8;
	211	break;
	212	case 16:
	213	cur->bsr_type = BSR_16;
	214	break;
	215	case 64:
	216	cur->bsr_type = BSR_64;
	217	break;
	218	case 128:
	219	cur->bsr_type = BSR_128;
	220	break;
	221	default:
	222	cur->bsr_type = BSR_UNKNOWN;
	223	printk(KERN_INFO "unknown BSR size %d\n",cur->bsr_bytes);
	224	}
	225
	226	cur->bsr_num = bsr_types[cur->bsr_type];
fe9e8d53 SR	227	snprintf(cur->bsr_name, 32, "bsr%d_%d",
	228	cur->bsr_bytes, cur->bsr_num);
	229
	230	cdev_init(&cur->bsr_cdev, &bsr_fops);
	231	result = cdev_add(&cur->bsr_cdev, cur->bsr_dev, 1);
a0e2f9f4 SR	232	if (result) {
a0e2f9f4 SR	233	kfree(cur);
fe9e8d53	234	goto out_err;
a0e2f9f4	235	}
fe9e8d53	236
03457cd4 GKH	237	cur->bsr_device = device_create(bsr_class, NULL, cur->bsr_dev,
03457cd4 GKH	238	cur, cur->bsr_name);
fe9e8d53 SR	239	if (!cur->bsr_device) {
	240	printk(KERN_ERR "device_create failed for %s\n",
	241	cur->bsr_name);
	242	cdev_del(&cur->bsr_cdev);
a0e2f9f4	243	kfree(cur);
fe9e8d53 SR	244	goto out_err;
fe9e8d53 SR	245	}
a0e2f9f4 SR	246
	247	bsr_types[cur->bsr_type] = cur->bsr_num + 1;
	248	list_add_tail(&cur->bsr_list, &bsr_devs);
fe9e8d53 SR	249	}
fe9e8d53 SR	250
a0e2f9f4 SR	251	total_bsr_devs += num_bsr_devs;
a0e2f9f4 SR	252
fe9e8d53 SR	253	return 0;
	254
	255	out_err:
	256
	257	bsr_cleanup_devs();
a0e2f9f4 SR	258	return ret;
	259	}
	260
	261	static int bsr_create_devs(struct device_node *bn)
	262	{
	263	int ret;
	264
	265	while (bn) {
	266	ret = bsr_add_node(bn);
	267	if (ret) {
	268	of_node_put(bn);
	269	return ret;
	270	}
	271	bn = of_find_compatible_node(bn, NULL, "ibm,bsr");
	272	}
	273	return 0;
fe9e8d53 SR	274	}
	275
	276	static int __init bsr_init(void)
	277	{
	278	struct device_node *np;
	279	dev_t bsr_dev = MKDEV(bsr_major, 0);
	280	int ret = -ENODEV;
	281	int result;
	282
a0e2f9f4	283	np = of_find_compatible_node(NULL, NULL, "ibm,bsr");
fe9e8d53 SR	284	if (!np)
	285	goto out_err;
	286
	287	bsr_class = class_create(THIS_MODULE, "bsr");
	288	if (IS_ERR(bsr_class)) {
	289	printk(KERN_ERR "class_create() failed for bsr_class\n");
	290	goto out_err_1;
	291	}
	292	bsr_class->dev_attrs = bsr_dev_attrs;
	293
	294	result = alloc_chrdev_region(&bsr_dev, 0, BSR_MAX_DEVS, "bsr");
	295	bsr_major = MAJOR(bsr_dev);
	296	if (result < 0) {
	297	printk(KERN_ERR "alloc_chrdev_region() failed for bsr\n");
	298	goto out_err_2;
	299	}
	300
a0e2f9f4 SR	301	if ((ret = bsr_create_devs(np)) < 0) {
a0e2f9f4 SR	302	np = NULL;
fe9e8d53	303	goto out_err_3;
a0e2f9f4	304	}
fe9e8d53 SR	305
	306	return 0;
	307
	308	out_err_3:
	309	unregister_chrdev_region(bsr_dev, BSR_MAX_DEVS);
	310
	311	out_err_2:
	312	class_destroy(bsr_class);
	313
	314	out_err_1:
	315	of_node_put(np);
	316
	317	out_err:
	318
	319	return ret;
	320	}
	321
	322	static void __exit bsr_exit(void)
	323	{
	324
	325	bsr_cleanup_devs();
	326
	327	if (bsr_class)
	328	class_destroy(bsr_class);
	329
	330	if (bsr_major)
	331	unregister_chrdev_region(MKDEV(bsr_major, 0), BSR_MAX_DEVS);
	332	}
	333
	334	module_init(bsr_init);
	335	module_exit(bsr_exit);
	336	MODULE_LICENSE("GPL");
	337	MODULE_AUTHOR("Sonny Rao <sonnyrao@us.ibm.com>");