diff options
Diffstat (limited to 'drivers/char/bsr.c')
| -rw-r--r-- | drivers/char/bsr.c | 361 |
1 files changed, 361 insertions, 0 deletions
diff --git a/drivers/char/bsr.c b/drivers/char/bsr.c new file mode 100644 index 000000000..a6cef548e --- /dev/null +++ b/drivers/char/bsr.c @@ -0,0 +1,361 @@ +/* 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_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/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 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; + } + + 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>"); |