--- /dev/null
+/* 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/module.h>
+#include <linux/cdev.h>
+#include <linux/list.h>
+#include <linux/mm.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;
+
+ dev_t bsr_dev;
+ struct cdev bsr_cdev;
+ struct device *bsr_device;
+ char bsr_name[32];
+
+};
+
+static unsigned num_bsr_devs;
+static struct bsr_dev *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_UNKNOWN = 4,
+ BSR_MAX = 5,
+};
+
+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, "%lu\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;
+
+ if (size > dev->bsr_len || (size & (PAGE_SIZE-1)))
+ return -EINVAL;
+
+ vma->vm_flags |= (VM_IO | VM_DONTEXPAND);
+ vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
+
+ if (io_remap_pfn_range(vma, vma->vm_start, dev->bsr_addr >> PAGE_SHIFT,
+ size, vma->vm_page_prot))
+ 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;
+}
+
+const static struct file_operations bsr_fops = {
+ .owner = THIS_MODULE,
+ .mmap = bsr_mmap,
+ .open = bsr_open,
+};
+
+static void bsr_cleanup_devs(void)
+{
+ int i;
+ for (i=0 ; i < num_bsr_devs; i++) {
+ struct bsr_dev *cur = bsr_devs + i;
+ if (cur->bsr_device) {
+ cdev_del(&cur->bsr_cdev);
+ device_del(cur->bsr_device);
+ }
+ }
+
+ kfree(bsr_devs);
+}
+
+static int bsr_create_devs(struct device_node *bn)
+{
+ int bsr_stride_len, bsr_bytes_len;
+ const u32 *bsr_stride;
+ const u32 *bsr_bytes;
+ unsigned i;
+
+ 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 -ENODEV;
+ }
+
+ num_bsr_devs = bsr_bytes_len / sizeof(u32);
+
+ /* only a warning, its informational since we'll fail and exit */
+ WARN_ON(num_bsr_devs > BSR_MAX_DEVS);
+
+ bsr_devs = kzalloc(sizeof(struct bsr_dev) * num_bsr_devs, GFP_KERNEL);
+ if (!bsr_devs)
+ return -ENOMEM;
+
+ for (i = 0 ; i < num_bsr_devs; i++) {
+ struct bsr_dev *cur = bsr_devs + i;
+ struct resource res;
+ int result;
+
+ result = of_address_to_resource(bn, i, &res);
+ if (result < 0) {
+ printk(KERN_ERR "bsr of-node has invalid reg property\n");
+ goto out_err;
+ }
+
+ cur->bsr_minor = i;
+ cur->bsr_addr = res.start;
+ cur->bsr_len = res.end - res.start + 1;
+ cur->bsr_bytes = bsr_bytes[i];
+ cur->bsr_stride = bsr_stride[i];
+ cur->bsr_dev = MKDEV(bsr_major, i);
+
+ 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;
+ default:
+ cur->bsr_type = BSR_UNKNOWN;
+ printk(KERN_INFO "unknown BSR size %d\n",cur->bsr_bytes);
+ }
+
+ cur->bsr_num = bsr_types[cur->bsr_type];
+ bsr_types[cur->bsr_type] = cur->bsr_num + 1;
+ 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)
+ goto out_err;
+
+ cur->bsr_device = device_create_drvdata(bsr_class, NULL,
+ cur->bsr_dev,
+ cur, cur->bsr_name);
+ if (!cur->bsr_device) {
+ printk(KERN_ERR "device_create failed for %s\n",
+ cur->bsr_name);
+ cdev_del(&cur->bsr_cdev);
+ goto out_err;
+ }
+ }
+
+ return 0;
+
+ out_err:
+
+ bsr_cleanup_devs();
+ return -ENODEV;
+}
+
+static int __init bsr_init(void)
+{
+ struct device_node *np;
+ dev_t bsr_dev = MKDEV(bsr_major, 0);
+ int ret = -ENODEV;
+ int result;
+
+ np = of_find_compatible_node(NULL, "ibm,bsr", "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");
+ goto out_err_1;
+ }
+ bsr_class->dev_attrs = bsr_dev_attrs;
+
+ result = alloc_chrdev_region(&bsr_dev, 0, BSR_MAX_DEVS, "bsr");
+ bsr_major = MAJOR(bsr_dev);
+ if (result < 0) {
+ printk(KERN_ERR "alloc_chrdev_region() failed for bsr\n");
+ goto out_err_2;
+ }
+
+ if ((ret = bsr_create_devs(np)) < 0)
+ goto out_err_3;
+
+ of_node_put(np);
+
+ 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>");
projects / cascardo / linux.git / commitdiff