[patch] mspec driver

Jes Sorensen
2006-09-20T07:26:55Z

Ohoy,

Another one to go on top of do_no_pfn() - no changes here either.

Cheers,
Jes

This patch implements the special memory driver (mspec) based on the
do_no_pfn approach. The driver is currently used only on SN2 hardware
with special fetchop support but could be beneficial on other
architectures using the uncached mode.

Signed-off-by: Jes Sorensen <jes@sgi.com>

----

drivers/char/Kconfig | 8
drivers/char/Makefile | 1
drivers/char/mspec.c | 421 ++++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 430 insertions(+)

Index: linux-2.6/drivers/char/Kconfig
===================================================================
--- linux-2.6.orig/drivers/char/Kconfig
+++ linux-2.6/drivers/char/Kconfig
@@ -439,6 +439,14 @@ config SGI_MBCS
If you have an SGI Altix with an attached SABrick
say Y or M here, otherwise say N.

+config MSPEC
+ tristate "Memory special operations driver"
+ depends on IA64
+ help
+ If you have an ia64 and you want to enable memory special
+ operations support (formerly known as fetchop), say Y here,
+ otherwise say N.
+
source "drivers/serial/Kconfig"

config UNIX98_PTYS
Index: linux-2.6/drivers/char/Makefile
===================================================================
--- linux-2.6.orig/drivers/char/Makefile
+++ linux-2.6/drivers/char/Makefile
@@ -51,6 +51,7 @@ obj-$(CONFIG_VIOCONS) += viocons.o
obj-$(CONFIG_VIOTAPE) += viotape.o
obj-$(CONFIG_HVCS) += hvcs.o
obj-$(CONFIG_SGI_MBCS) += mbcs.o
+obj-$(CONFIG_MSPEC) += mspec.o

obj-$(CONFIG_PRINTER) += lp.o
obj-$(CONFIG_TIPAR) += tipar.o
Index: linux-2.6/drivers/char/mspec.c
===================================================================
--- /dev/null
+++ linux-2.6/drivers/char/mspec.c
@@ -0,0 +1,421 @@
+/*
+ * Copyright (C) 2001-2006 Silicon Graphics, Inc. All rights
+ * reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of version 2 of the GNU General Public License
+ * as published by the Free Software Foundation.
+ */
+
+/*
+ * SN Platform Special Memory (mspec) Support
+ *
+ * This driver exports the SN special memory (mspec) facility to user
+ * processes.
+ * There are three types of memory made available thru this driver:
+ * fetchops, uncached and cached.
+ *
+ * Fetchops are atomic memory operations that are implemented in the
+ * memory controller on SGI SN hardware.
+ *
+ * Uncached are used for memory write combining feature of the ia64
+ * cpu.
+ *
+ * Cached are used for areas of memory that are used as cached addresses
+ * on our partition and used as uncached addresses from other partitions.
+ * Due to a design constraint of the SN2 Shub, you can not have processors
+ * on the same FSB perform both a cached and uncached reference to the
+ * same cache line. These special memory cached regions prevent the
+ * kernel from ever dropping in a TLB entry and therefore prevent the
+ * processor from ever speculating a cache line from this page.
+ */
+
+#include <linux/config.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/errno.h>
+#include <linux/miscdevice.h>
+#include <linux/spinlock.h>
+#include <linux/mm.h>
+#include <linux/vmalloc.h>
+#include <linux/string.h>
+#include <linux/slab.h>
+#include <linux/numa.h>
+#include <asm/page.h>
+#include <asm/system.h>
+#include <asm/pgtable.h>
+#include <asm/atomic.h>
+#include <asm/tlbflush.h>
+#include <asm/uncached.h>
+#include <asm/sn/addrs.h>
+#include <asm/sn/arch.h>
+#include <asm/sn/mspec.h>
+#include <asm/sn/sn_cpuid.h>
+#include <asm/sn/io.h>
+#include <asm/sn/bte.h>
+#include <asm/sn/shubio.h>
+
+
+#define FETCHOP_ID "SGI Fetchop,"
+#define CACHED_ID "Cached,"
+#define UNCACHED_ID "Uncached"
+#define REVISION "4.0"
+#define MSPEC_BASENAME "mspec"
+
+/*
+ * Page types allocated by the device.
+ */
+enum {
+ MSPEC_FETCHOP = 1,
+ MSPEC_CACHED,
+ MSPEC_UNCACHED
+};
+
+static int is_sn2;
+
+/*
+ * One of these structures is allocated when an mspec region is mmaped. The
+ * structure is pointed to by the vma->vm_private_data field in the vma struct.
+ * This structure is used to record the addresses of the mspec pages.
+ */
+struct vma_data {
+ atomic_t refcnt; /* Number of vmas sharing the data. */
+ spinlock_t lock; /* Serialize access to the vma. */
+ int count; /* Number of pages allocated. */
+ int type; /* Type of pages allocated. */
+ unsigned long maddr[0]; /* Array of MSPEC addresses. */
+};
+
+/* used on shub2 to clear FOP cache in the HUB */
+static unsigned long scratch_page[MAX_NUMNODES];
+#define SH2_AMO_CACHE_ENTRIES 4
+
+static inline int
+mspec_zero_block(unsigned long addr, int len)
+{
+ int status;
+
+ if (is_sn2) {
+ if (is_shub2()) {
+ int nid;
+ void *p;
+ int i;
+
+ nid = nasid_to_cnodeid(get_node_number(__pa(addr)));
+ p = (void *)TO_AMO(scratch_page[nid]);
+
+ for (i=0; i < SH2_AMO_CACHE_ENTRIES; i++) {
+ FETCHOP_LOAD_OP(p, FETCHOP_LOAD);
+ p += FETCHOP_VAR_SIZE;
+ }
+ }
+
+ status = bte_copy(0, addr & ~__IA64_UNCACHED_OFFSET, len,
+ BTE_WACQUIRE | BTE_ZERO_FILL, NULL);
+ } else {
+ memset((char *) addr, 0, len);
+ status = 0;
+ }
+ return status;
+}
+
+/*
+ * mspec_open
+ *
+ * Called when a device mapping is created by a means other than mmap
+ * (via fork, etc.). Increments the reference count on the underlying
+ * mspec data so it is not freed prematurely.
+ */
+static void
+mspec_open(struct vm_area_struct *vma)
+{
+ struct vma_data *vdata;
+
+ vdata = vma->vm_private_data;
+ atomic_inc(&vdata->refcnt);
+}
+
+/*
+ * mspec_close
+ *
+ * Called when unmapping a device mapping. Frees all mspec pages
+ * belonging to the vma.
+ */
+static void
+mspec_close(struct vm_area_struct *vma)
+{
+ struct vma_data *vdata;
+ int i, pages, result, vdata_size;
+
+ vdata = vma->vm_private_data;
+ if (!atomic_dec_and_test(&vdata->refcnt))
+ return;
+
+ pages = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
+ vdata_size = sizeof(struct vma_data) + pages * sizeof(long);
+ for (i = 0; i < pages; i++) {
+ if (vdata->maddr[i] == 0)
+ continue;
+ /*
+ * Clear the page before sticking it back
+ * into the pool.
+ */
+ result = mspec_zero_block(vdata->maddr[i], PAGE_SIZE);
+ if (!result)
+ uncached_free_page(vdata->maddr[i]);
+ else
+ printk(KERN_WARNING "mspec_close(): "
+ "failed to zero page %i\n",
+ result);
+ }
+
+ if (vdata_size <= PAGE_SIZE)
+ kfree(vdata);
+ else
+ vfree(vdata);
+}
+
+
+/*
+ * mspec_nopfn
+ *
+ * Creates a mspec page and maps it to user space.
+ */
+static unsigned long
+mspec_nopfn(struct vm_area_struct *vma, unsigned long address)
+{
+ unsigned long paddr, maddr;
+ unsigned long pfn;
+ int index;
+ struct vma_data *vdata = vma->vm_private_data;
+
+ index = (address - vma->vm_start) >> PAGE_SHIFT;
+ maddr = (volatile unsigned long) vdata->maddr[index];
+ if (maddr == 0) {
+ maddr = uncached_alloc_page(numa_node_id());
+ if (maddr == 0)
+ return NOPFN_OOM;
+
+ spin_lock(&vdata->lock);
+ if (vdata->maddr[index] == 0) {
+ vdata->count++;
+ vdata->maddr[index] = maddr;
+ } else {
+ uncached_free_page(maddr);
+ maddr = vdata->maddr[index];
+ }
+ spin_unlock(&vdata->lock);
+ }
+
+ if (vdata->type == MSPEC_FETCHOP)
+ paddr = TO_AMO(maddr);
+ else
+ paddr = __pa(TO_CAC(maddr));
+
+ pfn = paddr >> PAGE_SHIFT;
+
+ return pfn;
+}
+
+static struct vm_operations_struct mspec_vm_ops = {
+ .open = mspec_open,
+ .close = mspec_close,
+ .nopfn = mspec_nopfn
+};
+
+/*
+ * mspec_mmap
+ *
+ * Called when mmaping the device. Initializes the vma with a fault handler
+ * and private data structure necessary to allocate, track, and free the
+ * underlying pages.
+ */
+static int
+mspec_mmap(struct file *file, struct vm_area_struct *vma, int type)
+{
+ struct vma_data *vdata;
+ int pages, vdata_size;
+
+ if (vma->vm_pgoff != 0)
+ return -EINVAL;
+
+ if ((vma->vm_flags & VM_SHARED) == 0)
+ return -EINVAL;
+
+ if ((vma->vm_flags & VM_WRITE) == 0)
+ return -EPERM;
+
+ pages = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
+ vdata_size = sizeof(struct vma_data) + pages * sizeof(long);
+ if (vdata_size <= PAGE_SIZE)
+ vdata = kmalloc(vdata_size, GFP_KERNEL);
+ else
+ vdata = vmalloc(vdata_size);
+ if (!vdata)
+ return -ENOMEM;
+ memset(vdata, 0, vdata_size);
+
+ vdata->type = type;
+ spin_lock_init(&vdata->lock);
+ vdata->refcnt = ATOMIC_INIT(1);
+ vma->vm_private_data = vdata;
+
+ vma->vm_flags |= (VM_IO | VM_LOCKED | VM_RESERVED | VM_PFNMAP);
+ if (vdata->type == MSPEC_FETCHOP || vdata->type == MSPEC_UNCACHED)
+ vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
+ vma->vm_ops = &mspec_vm_ops;
+
+ return 0;
+}
+
+static int
+fetchop_mmap(struct file *file, struct vm_area_struct *vma)
+{
+ return mspec_mmap(file, vma, MSPEC_FETCHOP);
+}
+
+static int
+cached_mmap(struct file *file, struct vm_area_struct *vma)
+{
+ return mspec_mmap(file, vma, MSPEC_CACHED);
+}
+
+static int
+uncached_mmap(struct file *file, struct vm_area_struct *vma)
+{
+ return mspec_mmap(file, vma, MSPEC_UNCACHED);
+}
+
+static struct file_operations fetchop_fops = {
+ .owner = THIS_MODULE,
+ .mmap = fetchop_mmap
+};
+
+static struct miscdevice fetchop_miscdev = {
+ .minor = MISC_DYNAMIC_MINOR,
+ .name = "sgi_fetchop",
+ .fops = &fetchop_fops
+};
+
+static struct file_operations cached_fops = {
+ .owner = THIS_MODULE,
+ .mmap = cached_mmap
+};
+
+static struct miscdevice cached_miscdev = {
+ .minor = MISC_DYNAMIC_MINOR,
+ .name = "mspec_cached",
+ .fops = &cached_fops
+};
+
+static struct file_operations uncached_fops = {
+ .owner = THIS_MODULE,
+ .mmap = uncached_mmap
+};
+
+static struct miscdevice uncached_miscdev = {
+ .minor = MISC_DYNAMIC_MINOR,
+ .name = "mspec_uncached",
+ .fops = &uncached_fops
+};
+
+/*
+ * mspec_init
+ *
+ * Called at boot time to initialize the mspec facility.
+ */
+static int __init
+mspec_init(void)
+{
+ int ret;
+ int nid;
+
+ /*
+ * The fetchop device only works on SN2 hardware, uncached and cached
+ * memory drivers should both be valid on all ia64 hardware
+ */
+ if (ia64_platform_is("sn2")) {
+ is_sn2 = 1;
+ if (is_shub2()) {
+ ret = -ENOMEM;
+ for_each_online_node(nid) {
+ int actual_nid;
+ int nasid;
+ unsigned long phys;
+
+ scratch_page[nid] = uncached_alloc_page(nid);
+ if (scratch_page[nid] == 0)
+ goto free_scratch_pages;
+ phys = __pa(scratch_page[nid]);
+ nasid = get_node_number(phys);
+ actual_nid = nasid_to_cnodeid(nasid);
+ if (actual_nid != nid)
+ goto free_scratch_pages;
+ }
+ }
+
+ ret = misc_register(&fetchop_miscdev);
+ if (ret) {
+ printk(KERN_ERR
+ "%s: failed to register device %i\n",
+ FETCHOP_ID, ret);
+ goto free_scratch_pages;
+ }
+ }
+ ret = misc_register(&cached_miscdev);
+ if (ret) {
+ printk(KERN_ERR "%s: failed to register device %i\n",
+ CACHED_ID, ret);
+ if (is_sn2)
+ misc_deregister(&fetchop_miscdev);
+ goto free_scratch_pages;
+ }
+ ret = misc_register(&uncached_miscdev);
+ if (ret) {
+ printk(KERN_ERR "%s: failed to register device %i\n",
+ UNCACHED_ID, ret);
+ misc_deregister(&cached_miscdev);
+ if (is_sn2)
+ misc_deregister(&fetchop_miscdev);
+ goto free_scratch_pages;
+ }
+
+ printk(KERN_INFO "%s %s initialized devices: %s %s %s\n",
+ MSPEC_BASENAME, REVISION, is_sn2 ? FETCHOP_ID : "",
+ CACHED_ID, UNCACHED_ID);
+
+ return 0;
+
+ free_scratch_pages:
+ for_each_node(nid) {
+ if (scratch_page[nid] != 0)
+ uncached_free_page(scratch_page[nid]);
+ }
+ return ret;
+}
+
+static void __exit
+mspec_exit(void)
+{
+ int nid;
+
+ misc_deregister(&uncached_miscdev);
+ misc_deregister(&cached_miscdev);
+ if (is_sn2) {
+ misc_deregister(&fetchop_miscdev);
+
+ for_each_node(nid) {
+ if (scratch_page[nid] != 0)
+ uncached_free_page(scratch_page[nid]);
+ }
+ }
+}
+
+module_init(mspec_init);
+module_exit(mspec_exit);
+
+MODULE_AUTHOR("Silicon Graphics, Inc. <linux-altix@sgi.com>");
+MODULE_DESCRIPTION("Driver for SGI SN special memory operations");
+MODULE_LICENSE("GPL");