[PATCH] Power5,Power6 BSR driver

[PATCH] Power5,Power6 BSR driver

[jschopp]

From: Sonny Rao <sonnyrao@linux.vnet.ibm.com>

Adds a character driver for BSR support on IBM POWER systems including 
Power5 and Power6.  The BSR is an optional processor facility not currently 
implemented by any other processors.  It's primary purpose is large SMP 
synchronization.  More details on the BSR are in comments to the code which 
follows.

After addressing any issues from the community I'm hoping this can be queued
for 2.6.27.

Signed-off-by: Sonny Rao <sonnyrao@linux.vnet.ibm.com>
Signed-off-by: Joel Schopp <jschopp@austin.ibm.com>

Index: linux-2.6.24/drivers/char/bsr.c
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6.24/drivers/char/bsr.c	2008-06-04 12:09:20.000000000 -0500
@@ -0,0 +1,307 @@
+/* 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 reg_len, bsr_stride_len, bsr_bytes_len;
+	const u64 *reg;
+	const u32 *bsr_stride;
+	const u32 *bsr_bytes;
+	unsigned i;
+
+	reg        = of_get_property(bn, "reg", &reg_len);
+	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 (!reg || !bsr_stride || !bsr_bytes ||
+	    (bsr_stride_len != bsr_bytes_len) ||
+	    (bsr_stride_len/4 != reg_len/16)) {
+		printk(KERN_ERR "bsr of-node has missing/incorrect property\n");
+		return -ENODEV;
+	}
+
+	num_bsr_devs = reg_len/16;
+
+	/* 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;
+		int result;
+
+		cur->bsr_minor  = i;
+		cur->bsr_addr   = reg[i*2];
+		cur->bsr_len    = reg[i*2 + 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(bsr_class, NULL,
+						cur->bsr_dev,
+						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;
+		}
+		dev_set_drvdata(cur->bsr_device, cur);
+	}
+
+	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;
+	}
+	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_1;
+	}
+
+	if ((ret = bsr_create_devs(np)) < 0)
+		goto out_err_2;
+
+	of_node_put(np);
+
+	return 0;
+
+ out_err_2:
+	unregister_chrdev_region(bsr_dev, BSR_MAX_DEVS);
+
+ out_err_1:
+	class_destroy(bsr_class);
+	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>");
Index: linux-2.6.24/drivers/char/Makefile
===================================================================
--- linux-2.6.24.orig/drivers/char/Makefile	2008-06-04 11:00:01.000000000 -0500
+++ linux-2.6.24/drivers/char/Makefile	2008-06-04 11:00:18.000000000 -0500
@@ -57,6 +57,7 @@
 obj-$(CONFIG_VIOCONS)		+= viocons.o
 obj-$(CONFIG_VIOTAPE)		+= viotape.o
 obj-$(CONFIG_HVCS)		+= hvcs.o
+obj-$(CONFIG_IBM_BSR)		+= bsr.o
 obj-$(CONFIG_SGI_MBCS)		+= mbcs.o
 obj-$(CONFIG_BRIQ_PANEL)	+= briq_panel.o
 obj-$(CONFIG_BFIN_OTP)		+= bfin-otp.o
Index: linux-2.6.24/drivers/char/Kconfig
===================================================================
--- linux-2.6.24.orig/drivers/char/Kconfig	2008-06-04 11:00:01.000000000 -0500
+++ linux-2.6.24/drivers/char/Kconfig	2008-06-04 11:00:18.000000000 -0500
@@ -649,6 +649,14 @@
 	  which will also be compiled when this driver is built as a
 	  module.
 
+config IBM_BSR
+	tristate "IBM POWER Barrier Synchronization Register support"
+	depends on PPC_PSERIES
+	help
+	  This devices exposes a hardware mechanism for fast synchronization
+	  of threads across a large system which avoids bouncing a cacheline
+	  between several cores on a system
+
 source "drivers/char/ipmi/Kconfig"
 
 config DS1620

Re: [PATCH] Power5,Power6 BSR driver

[Nathan Lynch]

Hi, mainly a couple of coding style things, but one minor bug (I
think).

jschopp@austin.ibm.com wrote:
> From: Sonny Rao <sonnyrao@linux.vnet.ibm.com>
> 
> +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;

Indentation is wrong.


> +static void bsr_cleanup_devs(void)
> +{
> +	int i;
> +	for (i=0 ; i < num_bsr_devs; i++) {

             i = 0

> +		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 reg_len, bsr_stride_len, bsr_bytes_len;
> +	const u64 *reg;
> +	const u32 *bsr_stride;
> +	const u32 *bsr_bytes;
> +	unsigned i;
> +
> +	reg        = of_get_property(bn, "reg", &reg_len);
> +	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 (!reg || !bsr_stride || !bsr_bytes ||
> +	    (bsr_stride_len != bsr_bytes_len) ||
> +	    (bsr_stride_len/4 != reg_len/16)) {

             bsr_stride_len / 4 != reg_len / 16


> +		printk(KERN_ERR "bsr of-node has missing/incorrect property\n");
> +		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;

At this point I think you can leak a reference to np.


> +	}
> +	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_1;
> +	}
> +
> +	if ((ret = bsr_create_devs(np)) < 0)
> +		goto out_err_2;
> +
> +	of_node_put(np);
> +
> +	return 0;
> +
> + out_err_2:
> +	unregister_chrdev_region(bsr_dev, BSR_MAX_DEVS);
> +
> + out_err_1:
> +	class_destroy(bsr_class);
> +	of_node_put(np);
> +
> + out_err:
> +
> +	return ret;
> +}

Re: [PATCH] Power5,Power6 BSR driver

[Sonny Rao]

On Tue, Jun 17, 2008 at 05:39:52PM -0500, Nathan Lynch wrote:
> Hi, mainly a couple of coding style things, but one minor bug (I
> think).
> 
> jschopp@austin.ibm.com wrote:
> > From: Sonny Rao <sonnyrao@linux.vnet.ibm.com>
> > 
> > +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;
> 
> Indentation is wrong.

Yeah I noticed that too.

> > +static void bsr_cleanup_devs(void)
> > +{
> > +	int i;
> > +	for (i=0 ; i < num_bsr_devs; i++) {
> 
>              i = 0
> 
> > +		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 reg_len, bsr_stride_len, bsr_bytes_len;
> > +	const u64 *reg;
> > +	const u32 *bsr_stride;
> > +	const u32 *bsr_bytes;
> > +	unsigned i;
> > +
> > +	reg        = of_get_property(bn, "reg", &reg_len);
> > +	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 (!reg || !bsr_stride || !bsr_bytes ||
> > +	    (bsr_stride_len != bsr_bytes_len) ||
> > +	    (bsr_stride_len/4 != reg_len/16)) {
> 
>              bsr_stride_len / 4 != reg_len / 16
> 
> 
> > +		printk(KERN_ERR "bsr of-node has missing/incorrect property\n");
> > +		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;
> 
> At this point I think you can leak a reference to np.

Yeah, you're right.

> 
> > +	}
> > +	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_1;
> > +	}
> > +
> > +	if ((ret = bsr_create_devs(np)) < 0)
> > +		goto out_err_2;
> > +
> > +	of_node_put(np);
> > +
> > +	return 0;
> > +
> > + out_err_2:
> > +	unregister_chrdev_region(bsr_dev, BSR_MAX_DEVS);
> > +
> > + out_err_1:
> > +	class_destroy(bsr_class);
> > +	of_node_put(np);
> > +
> > + out_err:
> > +
> > +	return ret;
> > +}

Ok Will fix and send out again

-- 
Sonny Rao, LTC Ozlabs

Re: [PATCH] Power5,Power6 BSR driver

[Sonny Rao]

On Tue, Jun 17, 2008 at 05:44:43PM -0500, Sonny Rao wrote:
> On Tue, Jun 17, 2008 at 05:39:52PM -0500, Nathan Lynch wrote:
> > Hi, mainly a couple of coding style things, but one minor bug (I
> > think).
<snip>
> 
> Ok Will fix and send out again

From: Sonny Rao <sonnyrao@us.ibm.com>

Adds a character driver for BSR support on IBM POWER systems including 
Power5 and Power6.  The BSR is an optional processor facility not currently 
implemented by any other processors.  It's primary purpose is large SMP 
synchronization.  More details on the BSR are in comments to the code which 
follows.

After addressing any issues from the community I'm hoping this can be queued
for 2.6.27.

Signed-off-by: Sonny Rao <sonnyrao@us.ibm.com>
Signed-off-by: Joel Schopp <jschopp@austin.ibm.com>

Index: linux-2.6.24/drivers/char/bsr.c
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6.24/drivers/char/bsr.c	2008-06-18 01:45:49.000000000 -0500
@@ -0,0 +1,309 @@
+/* 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 reg_len, bsr_stride_len, bsr_bytes_len;
+	const u64 *reg;
+	const u32 *bsr_stride;
+	const u32 *bsr_bytes;
+	unsigned i;
+
+	reg        = of_get_property(bn, "reg", &reg_len);
+	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 (!reg || !bsr_stride || !bsr_bytes ||
+	    (bsr_stride_len != bsr_bytes_len) ||
+	    (bsr_stride_len / 4 != reg_len / 16)) {
+		printk(KERN_ERR "bsr of-node has missing/incorrect property\n");
+		return -ENODEV;
+	}
+
+	num_bsr_devs = reg_len / 16;
+
+	/* 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;
+		int result;
+
+		cur->bsr_minor  = i;
+		cur->bsr_addr   = reg[i * 2];
+		cur->bsr_len    = reg[i * 2 + 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(bsr_class, NULL,
+						cur->bsr_dev,
+						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;
+		}
+		dev_set_drvdata(cur->bsr_device, cur);
+	}
+
+	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>");
Index: linux-2.6.24/drivers/char/Makefile
===================================================================
--- linux-2.6.24.orig/drivers/char/Makefile	2008-06-18 01:24:04.000000000 -0500
+++ linux-2.6.24/drivers/char/Makefile	2008-06-18 01:38:30.000000000 -0500
@@ -57,6 +57,7 @@
 obj-$(CONFIG_VIOCONS)		+= viocons.o
 obj-$(CONFIG_VIOTAPE)		+= viotape.o
 obj-$(CONFIG_HVCS)		+= hvcs.o
+obj-$(CONFIG_IBM_BSR)		+= bsr.o
 obj-$(CONFIG_SGI_MBCS)		+= mbcs.o
 obj-$(CONFIG_BRIQ_PANEL)	+= briq_panel.o
 obj-$(CONFIG_BFIN_OTP)		+= bfin-otp.o
Index: linux-2.6.24/drivers/char/Kconfig
===================================================================
--- linux-2.6.24.orig/drivers/char/Kconfig	2008-06-18 01:24:04.000000000 -0500
+++ linux-2.6.24/drivers/char/Kconfig	2008-06-18 01:38:30.000000000 -0500
@@ -649,6 +649,14 @@
 	  which will also be compiled when this driver is built as a
 	  module.

+config IBM_BSR
+	tristate "IBM POWER Barrier Synchronization Register support"
+	depends on PPC_PSERIES
+	help
+	  This devices exposes a hardware mechanism for fast synchronization
+	  of threads across a large system which avoids bouncing a cacheline
+	  between several cores on a system
+
 source "drivers/char/ipmi/Kconfig"

 config DS1620

Re: [PATCH] Power5,Power6 BSR driver

[Sonny Rao]

On Mon, Jun 16, 2008 at 01:53:44PM -0500, jschopp@austin.ibm.com wrote:
> From: Sonny Rao <sonnyrao@linux.vnet.ibm.com>
> 
> Adds a character driver for BSR support on IBM POWER systems including 
> Power5 and Power6.  The BSR is an optional processor facility not currently 
> implemented by any other processors.  It's primary purpose is large SMP 
> synchronization.  More details on the BSR are in comments to the code which 
> follows.
> 


Here's a basic, quick n' dirty testcase I have
Remember to link w/ -lpthread


#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdint.h>
#include <pthread.h>

static void rw_test(char *map, unsigned bytes)
{
	unsigned i;
	printf("reading current bsr values\n");
	for (i=0 ; i < bytes;i++) {
		printf("bsr[%u] = 0x%x\n",
		       i, map[i]);
	}
	printf("writing all 1s into bsr\n");
	for (i=0; i< bytes; i++) {
		map[i] = 0xff;
	}
	printf("reading current bsr values\n");
	for (i=0 ; i < bytes;i++) {
		printf("bsr[%u] = 0x%x\n",
		       i, map[i]);
	}
	printf("writing all byte numbers into bsr\n");
	for (i=0; i< bytes; i++) {
		map[i] = i;
	}
	printf("reading current bsr values\n");
	for (i=0 ; i < bytes;i++) {
		printf("bsr[%u] = 0x%x\n",
		       i, map[i]);
	}

}

struct thread_data {
	pthread_t thread;
	volatile char *map;
	unsigned id;
	uint64_t counter;
};

#define be_busy(cycles) do { \
  __asm__ __volatile__ ("1: addic. %0,%0,-1\n" \
			"   bne 1b\n" : :"r" (cycles) : "cr0"); } while(0)
#define  __sync() do { \
  __asm__ __volatile__ ("sync\n" ::: "memory"); } while(0)

static
void * thread_fn(void * data)
{
	struct thread_data *mydata = data;

	__sync();
	mydata->map[mydata->id]++;
	__sync();
	while (mydata->map[0] == 0) {
		/* be_busy(10); */
		mydata->counter++;
	}
	return NULL;
}

static
void pthread_test(volatile char *map, unsigned num)
{
	struct thread_data *pthreads;
	unsigned i;

	pthreads = malloc(sizeof(struct thread_data) * num);
	if (!pthreads) {
		perror("malloc");
		return;
	}
	for (i=0; i<num; i++) {
		map[i] = 0;
	}
	__sync();
	for (i=1; i< num;i++) {
		struct thread_data *cur = &pthreads[i];
		cur->map = map;
		cur->id  = i;
		if (pthread_create(&cur->thread, NULL, thread_fn, cur)) {
			perror("pthread_create");
			exit(1);
		}
	}
	for (i=1; i<num;i++) {
		char status;
		do {
			status = map[i];
		} while(status == 0);
	}
	__sync();
	map[0] = 1;
	__sync();
	for (i=1; i<num;i++) {
		if (pthread_join(pthreads[i].thread, NULL)) {
			perror("pthread_join");
		}
		printf("%03u %llu\n", pthreads[i].id, pthreads[i].counter);
	}
	free(pthreads);
}

int main (int argc, char *argv[])
{
	char *file;
	int fd;
	char *map;
	int pagesize = getpagesize();
	unsigned  bytes;

	if (argc < 3) {
		fprintf(stderr, "usage: <bsr dev> <num bytes>\n");
		return 1;
	}
	file = argv[1];
	bytes = strtoul(argv[2], NULL, 0);
	fd = open(file, O_RDWR);
	if (fd < 0) {
		perror("open");
		return 1;
	}
	map = mmap(NULL, pagesize, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
	if (!map) {
		perror("mmap");
		close(fd);
		return 1;
	}

	rw_test(map, bytes);
	pthread_test(map, bytes);
	close(fd);
	return 0;
}

Re: [PATCH] Power5,Power6 BSR driver

[Benjamin Herrenschmidt]

> +		cur->bsr_addr   = reg[i * 2];
> +		cur->bsr_len    = reg[i * 2 + 1];

That's fishy... hand-reading of "reg" property without taking
into account the parent's #size-cells/#address-cells... can't you
use of_address_to_resource or something similar and carry a struct
resource around instead ?

In fact, same goes with the way you do num_bsr_devs = reg_len / 16.

You should rather use -another- property of well known lenght, or
get the #address/#size-cells of the parent and use those appropriately.

Cheers,
Ben.

Re: [PATCH] Power5,Power6 BSR driver

[Sonny Rao]

On Mon, Jul 07, 2008 at 02:59:35PM +1000, Benjamin Herrenschmidt wrote:
> 
> > +		cur->bsr_addr   = reg[i * 2];
> > +		cur->bsr_len    = reg[i * 2 + 1];
> 
> That's fishy... hand-reading of "reg" property without taking
> into account the parent's #size-cells/#address-cells... can't you
> use of_address_to_resource or something similar and carry a struct
> resource around instead ?

So, with this suggestion I looked at the resource API... not very well
documented, and I get the feeling like it's more for carving up a PCI
memory address range.  In the case of the BSR, everything is already
partitioned (by hardware) so I don't see the point of using this API
here.  Or am I missing something about it?

> In fact, same goes with the way you do num_bsr_devs = reg_len / 16.
> 
> You should rather use -another- property of well known lenght, or
> get the #address/#size-cells of the parent and use those appropriately.

Well, I check to make sure the lengths are consistent with each other
right above there so we shouldn't walk off the end of anything, but I
will take a look at using #size-cells / #address-cells instead.

Thanks for the comments

Sonny

Re: [PATCH] Power5,Power6 BSR driver

[Benjamin Herrenschmidt]

On Mon, 2008-07-07 at 16:17 -0500, Sonny Rao wrote:
> On Mon, Jul 07, 2008 at 02:59:35PM +1000, Benjamin Herrenschmidt wrote:
> > 
> > > +		cur->bsr_addr   = reg[i * 2];
> > > +		cur->bsr_len    = reg[i * 2 + 1];
> > 
> > That's fishy... hand-reading of "reg" property without taking
> > into account the parent's #size-cells/#address-cells... can't you
> > use of_address_to_resource or something similar and carry a struct
> > resource around instead ?
> 
> So, with this suggestion I looked at the resource API... not very well
> documented, and I get the feeling like it's more for carving up a PCI
> memory address range.  In the case of the BSR, everything is already
> partitioned (by hardware) so I don't see the point of using this API
> here.  Or am I missing something about it?

It's about properly parsing a "reg" property in OF. The format of the
reg property depends on the parent #address-cells and #size-cells, and
the addresses in there may need remapping (or not) depending on parent
"ranges" properties. The special cases in prom_parse.c for PCI and ISA
are purely to deal with the additional address space flags those add to
addresses, but you shouldn't hit that with BSR.

> > In fact, same goes with the way you do num_bsr_devs = reg_len / 16.
> > 
> > You should rather use -another- property of well known lenght, or
> > get the #address/#size-cells of the parent and use those appropriately.
> 
> Well, I check to make sure the lengths are consistent with each other
> right above there so we shouldn't walk off the end of anything, but I
> will take a look at using #size-cells / #address-cells instead.

The code in prom_parse.c will do it for you :-)

Cheers,
Ben.

[PATCHv3] Power5,Power6 BSR driver

[Sonny Rao]

On Tue, Jul 08, 2008 at 08:26:57AM +1000, Benjamin Herrenschmidt wrote:
> On Mon, 2008-07-07 at 16:17 -0500, Sonny Rao wrote:
> > On Mon, Jul 07, 2008 at 02:59:35PM +1000, Benjamin Herrenschmidt wrote:
> > > 
> > > > +		cur->bsr_addr   = reg[i * 2];
> > > > +		cur->bsr_len    = reg[i * 2 + 1];
> > > 
> > > That's fishy... hand-reading of "reg" property without taking
> > > into account the parent's #size-cells/#address-cells... can't you
> > > use of_address_to_resource or something similar and carry a struct
> > > resource around instead ?
> > 
> > So, with this suggestion I looked at the resource API... not very well
> > documented, and I get the feeling like it's more for carving up a PCI
> > memory address range.  In the case of the BSR, everything is already
> > partitioned (by hardware) so I don't see the point of using this API
> > here.  Or am I missing something about it?
> 
> It's about properly parsing a "reg" property in OF. The format of the
> reg property depends on the parent #address-cells and #size-cells, and
> the addresses in there may need remapping (or not) depending on parent
> "ranges" properties. The special cases in prom_parse.c for PCI and ISA
> are purely to deal with the additional address space flags those add to
> addresses, but you shouldn't hit that with BSR.
> 
> > > In fact, same goes with the way you do num_bsr_devs = reg_len / 16.
> > > 
> > > You should rather use -another- property of well known lenght, or
> > > get the #address/#size-cells of the parent and use those appropriately.
> > 
> > Well, I check to make sure the lengths are consistent with each other
> > right above there so we shouldn't walk off the end of anything, but I
> > will take a look at using #size-cells / #address-cells instead.
> 
> The code in prom_parse.c will do it for you :-)

From: Sonny Rao <sonnyrao@linux.vnet.ibm.com>

Adds a character driver for BSR support on IBM POWER systems including 
Power5 and Power6.  The BSR is an optional processor facility not currently 
implemented by any other processors.  It's primary purpose is fast large SMP 
synchronization.  More details on the BSR are in comments to the code which 
follows.  Patch adds BSR to pseries_defconfig


Signed-off-by: Sonny Rao <sonnyrao@linux.vnet.ibm.com>
Signed-off-by: Joel Schopp <jschopp@austin.ibm.com>

Index: linux-dev/drivers/char/bsr.c
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ linux-dev/drivers/char/bsr.c	2008-07-07 21:49:06.000000000 -0500
@@ -0,0 +1,313 @@
+/* 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(bsr_class, NULL,
+						cur->bsr_dev,
+						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;
+		}
+		dev_set_drvdata(cur->bsr_device, cur);
+	}
+
+	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>");
Index: linux-dev/drivers/char/Makefile
===================================================================
--- linux-dev.orig/drivers/char/Makefile	2008-06-18 01:24:04.000000000 -0500
+++ linux-dev/drivers/char/Makefile	2008-06-18 01:38:30.000000000 -0500
@@ -57,6 +57,7 @@
 obj-$(CONFIG_VIOCONS)		+= viocons.o
 obj-$(CONFIG_VIOTAPE)		+= viotape.o
 obj-$(CONFIG_HVCS)		+= hvcs.o
+obj-$(CONFIG_IBM_BSR)		+= bsr.o
 obj-$(CONFIG_SGI_MBCS)		+= mbcs.o
 obj-$(CONFIG_BRIQ_PANEL)	+= briq_panel.o
 obj-$(CONFIG_BFIN_OTP)		+= bfin-otp.o
Index: linux-dev/drivers/char/Kconfig
===================================================================
--- linux-dev.orig/drivers/char/Kconfig	2008-06-18 01:24:04.000000000 -0500
+++ linux-dev/drivers/char/Kconfig	2008-06-18 01:38:30.000000000 -0500
@@ -649,6 +649,14 @@
 	  which will also be compiled when this driver is built as a
 	  module.
 
+config IBM_BSR
+	tristate "IBM POWER Barrier Synchronization Register support"
+	depends on PPC_PSERIES
+	help
+	  This devices exposes a hardware mechanism for fast synchronization
+	  of threads across a large system which avoids bouncing a cacheline
+	  between several cores on a system
+
 source "drivers/char/ipmi/Kconfig"
 
 config DS1620
Index: linux-dev/arch/powerpc/configs/pseries_defconfig
===================================================================
--- linux-dev.orig/arch/powerpc/configs/pseries_defconfig	2008-07-07 20:44:42.000000000 -0500
+++ linux-dev/arch/powerpc/configs/pseries_defconfig	2008-07-07 20:45:21.000000000 -0500
@@ -946,6 +946,7 @@
 CONFIG_HVC_CONSOLE=y
 CONFIG_HVC_RTAS=y
 CONFIG_HVCS=m
+CONFIG_IBM_BSR=m
 # CONFIG_IPMI_HANDLER is not set
 # CONFIG_HW_RANDOM is not set
 CONFIG_GEN_RTC=y

Re: [PATCHv3] Power5,Power6 BSR driver

[Stephen Rothwell]

[-- Attachment #1: Type: text/plain, Size: 711 bytes --]

Hi Sonny,

On Mon, 7 Jul 2008 21:58:12 -0500 Sonny Rao <sonnyrao@us.ibm.com> wrote:
>
> +static int bsr_create_devs(struct device_node *bn)
> +{

> +		cur->bsr_device = device_create(bsr_class, NULL,
> +						cur->bsr_dev,
> +						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;
> +		}
> +		dev_set_drvdata(cur->bsr_device, cur);

device_create() is being removed in 2.6.27 because the above introduces a
race, use device_create_drvdata() instead.

-- 
Cheers,
Stephen Rothwell                    sfr@canb.auug.org.au
http://www.canb.auug.org.au/~sfr/

[-- Attachment #2: Type: application/pgp-signature, Size: 197 bytes --]

Re: [PATCHv4] Power5,Power6 BSR driver

[Sonny Rao]

On Tue, Jul 08, 2008 at 02:52:34PM +1000, Stephen Rothwell wrote:
> Hi Sonny,
> 
> On Mon, 7 Jul 2008 21:58:12 -0500 Sonny Rao <sonnyrao@us.ibm.com> wrote:
> >
> > +static int bsr_create_devs(struct device_node *bn)
> > +{
> 
> > +		cur->bsr_device = device_create(bsr_class, NULL,
> > +						cur->bsr_dev,
> > +						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;
> > +		}
> > +		dev_set_drvdata(cur->bsr_device, cur);
> 
> device_create() is being removed in 2.6.27 because the above introduces a
> race, use device_create_drvdata() instead.
> 

Stephen, thanks for the heads up. 

From: Sonny Rao <sonnyrao@linux.vnet.ibm.com>

Adds a character driver for BSR support on IBM POWER systems including 
Power5 and Power6.  The BSR is an optional processor facility not currently 
implemented by any other processors.  It's primary purpose is fast large SMP 
synchronization.  More details on the BSR are in comments to the code which 
follows.  This patch adds BSR driver to pseries_defconfig.

Signed-off-by: Sonny Rao <sonnyrao@linux.vnet.ibm.com>
Signed-off-by: Joel Schopp <jschopp@austin.ibm.com>

Index: linux-dev/drivers/char/bsr.c
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ linux-dev/drivers/char/bsr.c	2008-07-08 00:29:22.000000000 -0500
@@ -0,0 +1,312 @@
+/* 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>");
Index: linux-dev/drivers/char/Makefile
===================================================================
--- linux-dev.orig/drivers/char/Makefile	2008-06-18 01:24:04.000000000 -0500
+++ linux-dev/drivers/char/Makefile	2008-06-18 01:38:30.000000000 -0500
@@ -57,6 +57,7 @@
 obj-$(CONFIG_VIOCONS)		+= viocons.o
 obj-$(CONFIG_VIOTAPE)		+= viotape.o
 obj-$(CONFIG_HVCS)		+= hvcs.o
+obj-$(CONFIG_IBM_BSR)		+= bsr.o
 obj-$(CONFIG_SGI_MBCS)		+= mbcs.o
 obj-$(CONFIG_BRIQ_PANEL)	+= briq_panel.o
 obj-$(CONFIG_BFIN_OTP)		+= bfin-otp.o
Index: linux-dev/drivers/char/Kconfig
===================================================================
--- linux-dev.orig/drivers/char/Kconfig	2008-06-18 01:24:04.000000000 -0500
+++ linux-dev/drivers/char/Kconfig	2008-06-18 01:38:30.000000000 -0500
@@ -649,6 +649,14 @@
 	  which will also be compiled when this driver is built as a
 	  module.
 
+config IBM_BSR
+	tristate "IBM POWER Barrier Synchronization Register support"
+	depends on PPC_PSERIES
+	help
+	  This devices exposes a hardware mechanism for fast synchronization
+	  of threads across a large system which avoids bouncing a cacheline
+	  between several cores on a system
+
 source "drivers/char/ipmi/Kconfig"
 
 config DS1620
Index: linux-dev/arch/powerpc/configs/pseries_defconfig
===================================================================
--- linux-dev.orig/arch/powerpc/configs/pseries_defconfig	2008-07-07 20:44:42.000000000 -0500
+++ linux-dev/arch/powerpc/configs/pseries_defconfig	2008-07-07 20:45:21.000000000 -0500
@@ -946,6 +946,7 @@
 CONFIG_HVC_CONSOLE=y
 CONFIG_HVC_RTAS=y
 CONFIG_HVCS=m
+CONFIG_IBM_BSR=m
 # CONFIG_IPMI_HANDLER is not set
 # CONFIG_HW_RANDOM is not set
 CONFIG_GEN_RTC=y