1 files changed, 346 insertions, 0 deletions
diff --git a/drivers/char/bsr.c b/drivers/char/bsr.c
new file mode 100644
index 0000000000..70d31aed90
--- /dev/null
+++ b/drivers/char/bsr.c
@@ -0,0 +1,346 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* IBM POWER Barrier Synchronization Register Driver
+ *
+ * Copyright IBM Corporation 2008
+ *
+ * Author: Sonny Rao <sonnyrao@us.ibm.com>
+ */
+
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/fs.h>
+#include <linux/module.h>
+#include <linux/cdev.h>
+#include <linux/list.h>
+#include <linux/mm.h>
+#include <linux/slab.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 LIST_HEAD(bsr_devs);
+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 DEVICE_ATTR_RO(bsr_size);
+
+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 DEVICE_ATTR_RO(bsr_stride);
+
+static ssize_t
+bsr_length_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 DEVICE_ATTR_RO(bsr_length);
+
+static struct attribute *bsr_dev_attrs[] = {
+	&dev_attr_bsr_size.attr,
+	&dev_attr_bsr_stride.attr,
+	&dev_attr_bsr_length.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(bsr_dev);
+
+static const struct class bsr_class = {
+	.name		= "bsr",
+	.dev_groups	= bsr_dev_groups,
+};
+
+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,
+	.llseek = noop_llseek,
+};
+
+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    = resource_size(&res);
+		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, "%s", cur->bsr_name);
+		if (IS_ERR(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;
+	int ret = -ENODEV;
+
+	np = of_find_compatible_node(NULL, NULL, "ibm,bsr");
+	if (!np)
+		goto out_err;
+
+	ret = class_register(&bsr_class);
+	if (ret)
+		goto out_err_1;
+
+	ret = alloc_chrdev_region(&bsr_dev, 0, BSR_MAX_DEVS, "bsr");
+	bsr_major = MAJOR(bsr_dev);
+	if (ret < 0) {
+		printk(KERN_ERR "alloc_chrdev_region() failed for bsr\n");
+		goto out_err_2;
+	}
+
+	ret = bsr_create_devs(np);
+	if (ret < 0) {
+		np = NULL;
+		goto out_err_3;
+	}
+
+	return 0;
+
+ out_err_3:
+	unregister_chrdev_region(bsr_dev, BSR_MAX_DEVS);
+
+ out_err_2:
+	class_unregister(&bsr_class);
+
+ out_err_1:
+	of_node_put(np);
+
+ out_err:
+
+	return ret;
+}
+
+static void __exit  bsr_exit(void)
+{
+
+	bsr_cleanup_devs();
+
+	class_unregister(&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>");