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-rw-r--r--drivers/char/bsr.c348
1 files changed, 348 insertions, 0 deletions
diff --git a/drivers/char/bsr.c b/drivers/char/bsr.c
new file mode 100644
index 000000000..d5f943938
--- /dev/null
+++ b/drivers/char/bsr.c
@@ -0,0 +1,348 @@
+// 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/kernel.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_device.h>
+#include <linux/of_platform.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 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 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 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;
+
+ bsr_class = class_create(THIS_MODULE, "bsr");
+ if (IS_ERR(bsr_class)) {
+ printk(KERN_ERR "class_create() failed for bsr_class\n");
+ ret = PTR_ERR(bsr_class);
+ goto out_err_1;
+ }
+ bsr_class->dev_groups = bsr_dev_groups;
+
+ 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_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>");
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