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![Cai Huoqing](/assets/img/avatar_default.png)
Replace "struct list_head head = LIST_HEAD_INIT(head)" with "LIST_HEAD(head)" to simplify the code. Signed-off-by: Cai Huoqing <cai.huoqing@linux.dev> Link: https://lore.kernel.org/r/20220209032450.37849-1-cai.huoqing@linux.dev Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
348 lines
8.2 KiB
C
348 lines
8.2 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/* IBM POWER Barrier Synchronization Register Driver
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*
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* Copyright IBM Corporation 2008
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*
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* Author: Sonny Rao <sonnyrao@us.ibm.com>
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*/
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#include <linux/kernel.h>
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#include <linux/of.h>
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#include <linux/of_address.h>
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#include <linux/of_device.h>
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#include <linux/of_platform.h>
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#include <linux/fs.h>
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#include <linux/module.h>
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#include <linux/cdev.h>
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#include <linux/list.h>
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#include <linux/mm.h>
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#include <linux/slab.h>
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#include <asm/io.h>
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/*
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This driver exposes a special register which can be used for fast
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synchronization across a large SMP machine. The hardware is exposed
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as an array of bytes where each process will write to one of the bytes to
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indicate it has finished the current stage and this update is broadcast to
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all processors without having to bounce a cacheline between them. In
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POWER5 and POWER6 there is one of these registers per SMP, but it is
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presented in two forms; first, it is given as a whole and then as a number
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of smaller registers which alias to parts of the single whole register.
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This can potentially allow multiple groups of processes to each have their
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own private synchronization device.
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Note that this hardware *must* be written to using *only* single byte writes.
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It may be read using 1, 2, 4, or 8 byte loads which must be aligned since
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this region is treated as cache-inhibited processes should also use a
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full sync before and after writing to the BSR to ensure all stores and
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the BSR update have made it to all chips in the system
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*/
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/* This is arbitrary number, up to Power6 it's been 17 or fewer */
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#define BSR_MAX_DEVS (32)
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struct bsr_dev {
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u64 bsr_addr; /* Real address */
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u64 bsr_len; /* length of mem region we can map */
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unsigned bsr_bytes; /* size of the BSR reg itself */
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unsigned bsr_stride; /* interval at which BSR repeats in the page */
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unsigned bsr_type; /* maps to enum below */
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unsigned bsr_num; /* bsr id number for its type */
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int bsr_minor;
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struct list_head bsr_list;
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dev_t bsr_dev;
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struct cdev bsr_cdev;
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struct device *bsr_device;
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char bsr_name[32];
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};
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static unsigned total_bsr_devs;
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static LIST_HEAD(bsr_devs);
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static struct class *bsr_class;
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static int bsr_major;
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enum {
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BSR_8 = 0,
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BSR_16 = 1,
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BSR_64 = 2,
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BSR_128 = 3,
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BSR_4096 = 4,
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BSR_UNKNOWN = 5,
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BSR_MAX = 6,
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};
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static unsigned bsr_types[BSR_MAX];
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static ssize_t
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bsr_size_show(struct device *dev, struct device_attribute *attr, char *buf)
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{
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struct bsr_dev *bsr_dev = dev_get_drvdata(dev);
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return sprintf(buf, "%u\n", bsr_dev->bsr_bytes);
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}
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static DEVICE_ATTR_RO(bsr_size);
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static ssize_t
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bsr_stride_show(struct device *dev, struct device_attribute *attr, char *buf)
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{
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struct bsr_dev *bsr_dev = dev_get_drvdata(dev);
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return sprintf(buf, "%u\n", bsr_dev->bsr_stride);
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}
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static DEVICE_ATTR_RO(bsr_stride);
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static ssize_t
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bsr_length_show(struct device *dev, struct device_attribute *attr, char *buf)
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{
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struct bsr_dev *bsr_dev = dev_get_drvdata(dev);
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return sprintf(buf, "%llu\n", bsr_dev->bsr_len);
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}
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static DEVICE_ATTR_RO(bsr_length);
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static struct attribute *bsr_dev_attrs[] = {
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&dev_attr_bsr_size.attr,
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&dev_attr_bsr_stride.attr,
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&dev_attr_bsr_length.attr,
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NULL,
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};
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ATTRIBUTE_GROUPS(bsr_dev);
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static int bsr_mmap(struct file *filp, struct vm_area_struct *vma)
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{
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unsigned long size = vma->vm_end - vma->vm_start;
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struct bsr_dev *dev = filp->private_data;
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int ret;
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vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
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/* check for the case of a small BSR device and map one 4k page for it*/
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if (dev->bsr_len < PAGE_SIZE && size == PAGE_SIZE)
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ret = remap_4k_pfn(vma, vma->vm_start, dev->bsr_addr >> 12,
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vma->vm_page_prot);
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else if (size <= dev->bsr_len)
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ret = io_remap_pfn_range(vma, vma->vm_start,
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dev->bsr_addr >> PAGE_SHIFT,
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size, vma->vm_page_prot);
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else
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return -EINVAL;
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if (ret)
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return -EAGAIN;
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return 0;
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}
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static int bsr_open(struct inode *inode, struct file *filp)
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{
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struct cdev *cdev = inode->i_cdev;
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struct bsr_dev *dev = container_of(cdev, struct bsr_dev, bsr_cdev);
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filp->private_data = dev;
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return 0;
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}
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static const struct file_operations bsr_fops = {
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.owner = THIS_MODULE,
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.mmap = bsr_mmap,
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.open = bsr_open,
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.llseek = noop_llseek,
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};
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static void bsr_cleanup_devs(void)
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{
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struct bsr_dev *cur, *n;
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list_for_each_entry_safe(cur, n, &bsr_devs, bsr_list) {
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if (cur->bsr_device) {
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cdev_del(&cur->bsr_cdev);
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device_del(cur->bsr_device);
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}
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list_del(&cur->bsr_list);
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kfree(cur);
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}
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}
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static int bsr_add_node(struct device_node *bn)
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{
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int bsr_stride_len, bsr_bytes_len, num_bsr_devs;
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const u32 *bsr_stride;
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const u32 *bsr_bytes;
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unsigned i;
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int ret = -ENODEV;
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bsr_stride = of_get_property(bn, "ibm,lock-stride", &bsr_stride_len);
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bsr_bytes = of_get_property(bn, "ibm,#lock-bytes", &bsr_bytes_len);
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if (!bsr_stride || !bsr_bytes ||
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(bsr_stride_len != bsr_bytes_len)) {
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printk(KERN_ERR "bsr of-node has missing/incorrect property\n");
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return ret;
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}
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num_bsr_devs = bsr_bytes_len / sizeof(u32);
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for (i = 0 ; i < num_bsr_devs; i++) {
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struct bsr_dev *cur = kzalloc(sizeof(struct bsr_dev),
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GFP_KERNEL);
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struct resource res;
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int result;
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if (!cur) {
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printk(KERN_ERR "Unable to alloc bsr dev\n");
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ret = -ENOMEM;
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goto out_err;
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}
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result = of_address_to_resource(bn, i, &res);
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if (result < 0) {
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printk(KERN_ERR "bsr of-node has invalid reg property, skipping\n");
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kfree(cur);
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continue;
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}
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cur->bsr_minor = i + total_bsr_devs;
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cur->bsr_addr = res.start;
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cur->bsr_len = resource_size(&res);
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cur->bsr_bytes = bsr_bytes[i];
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cur->bsr_stride = bsr_stride[i];
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cur->bsr_dev = MKDEV(bsr_major, i + total_bsr_devs);
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/* if we have a bsr_len of > 4k and less then PAGE_SIZE (64k pages) */
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/* we can only map 4k of it, so only advertise the 4k in sysfs */
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if (cur->bsr_len > 4096 && cur->bsr_len < PAGE_SIZE)
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cur->bsr_len = 4096;
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switch(cur->bsr_bytes) {
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case 8:
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cur->bsr_type = BSR_8;
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break;
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case 16:
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cur->bsr_type = BSR_16;
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break;
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case 64:
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cur->bsr_type = BSR_64;
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break;
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case 128:
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cur->bsr_type = BSR_128;
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break;
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case 4096:
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cur->bsr_type = BSR_4096;
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break;
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default:
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cur->bsr_type = BSR_UNKNOWN;
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}
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cur->bsr_num = bsr_types[cur->bsr_type];
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snprintf(cur->bsr_name, 32, "bsr%d_%d",
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cur->bsr_bytes, cur->bsr_num);
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cdev_init(&cur->bsr_cdev, &bsr_fops);
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result = cdev_add(&cur->bsr_cdev, cur->bsr_dev, 1);
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if (result) {
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kfree(cur);
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goto out_err;
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}
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cur->bsr_device = device_create(bsr_class, NULL, cur->bsr_dev,
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cur, "%s", cur->bsr_name);
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if (IS_ERR(cur->bsr_device)) {
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printk(KERN_ERR "device_create failed for %s\n",
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cur->bsr_name);
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cdev_del(&cur->bsr_cdev);
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kfree(cur);
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goto out_err;
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}
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bsr_types[cur->bsr_type] = cur->bsr_num + 1;
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list_add_tail(&cur->bsr_list, &bsr_devs);
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}
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total_bsr_devs += num_bsr_devs;
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return 0;
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out_err:
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bsr_cleanup_devs();
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return ret;
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}
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static int bsr_create_devs(struct device_node *bn)
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{
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int ret;
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while (bn) {
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ret = bsr_add_node(bn);
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if (ret) {
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of_node_put(bn);
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return ret;
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}
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bn = of_find_compatible_node(bn, NULL, "ibm,bsr");
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}
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return 0;
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}
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static int __init bsr_init(void)
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{
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struct device_node *np;
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dev_t bsr_dev;
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int ret = -ENODEV;
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np = of_find_compatible_node(NULL, NULL, "ibm,bsr");
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if (!np)
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goto out_err;
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bsr_class = class_create(THIS_MODULE, "bsr");
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if (IS_ERR(bsr_class)) {
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printk(KERN_ERR "class_create() failed for bsr_class\n");
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ret = PTR_ERR(bsr_class);
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goto out_err_1;
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}
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bsr_class->dev_groups = bsr_dev_groups;
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ret = alloc_chrdev_region(&bsr_dev, 0, BSR_MAX_DEVS, "bsr");
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bsr_major = MAJOR(bsr_dev);
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if (ret < 0) {
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printk(KERN_ERR "alloc_chrdev_region() failed for bsr\n");
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goto out_err_2;
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}
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ret = bsr_create_devs(np);
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if (ret < 0) {
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np = NULL;
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goto out_err_3;
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}
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return 0;
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out_err_3:
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unregister_chrdev_region(bsr_dev, BSR_MAX_DEVS);
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out_err_2:
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class_destroy(bsr_class);
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out_err_1:
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of_node_put(np);
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out_err:
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return ret;
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}
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static void __exit bsr_exit(void)
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{
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bsr_cleanup_devs();
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if (bsr_class)
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class_destroy(bsr_class);
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if (bsr_major)
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unregister_chrdev_region(MKDEV(bsr_major, 0), BSR_MAX_DEVS);
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}
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module_init(bsr_init);
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module_exit(bsr_exit);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Sonny Rao <sonnyrao@us.ibm.com>");
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