| /* 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/fs.h> |
| #include <linux/module.h> |
| #include <linux/cdev.h> |
| #include <linux/list.h> |
| #include <linux/mm.h> |
| #include <linux/slab.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, |
| .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, 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_attrs = bsr_dev_attrs; |
| |
| 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; |
| } |
| |
| 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>"); |