/*
* 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/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/fs.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_page_type {
MSPEC_FETCHOP = 1,
MSPEC_CACHED,
MSPEC_UNCACHED
};
#ifdef CONFIG_SGI_SN
static int is_sn2;
#else
#define is_sn2 0
#endif
/*
* 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.
* This structure is shared by all vma's that are split off from the
* original vma when split_vma()'s are done.
*
* The refcnt is incremented atomically because mm->mmap_sem does not
* protect in fork case where multiple tasks share the vma_data.
*/
struct vma_data {
atomic_t refcnt; /* Number of vmas sharing the data. */
spinlock_t lock; /* Serialize access to this structure. */
int count; /* Number of pages allocated. */
enum mspec_page_type type; /* Type of pages allocated. */
int flags; /* See VMD_xxx below. */
unsigned long vm_start; /* Original (unsplit) base. */
unsigned long vm_end; /* Original (unsplit) end. */
unsigned long maddr[0]; /* Array of MSPEC addresses. */
};
#define VMD_VMALLOCED 0x1 /* vmalloc'd rather than kmalloc'd */
/* 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, munmap, 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 all the vma's sharing this vma_data structure.
*/
static void
mspec_close(struct vm_area_struct *vma)
{
struct vma_data *vdata;
int index, last_index;
unsigned long my_page;
vdata = vma->vm_private_data;
if (!atomic_dec_and_test(&vdata->refcnt))
return;
last_index = (vdata->vm_end - vdata->vm_start) >> PAGE_SHIFT;
for (index = 0; index < last_index; index++) {
if (vdata->maddr[index] == 0)
continue;
/*
* Clear the page before sticking it back
* into the pool.
*/
my_page = vdata->maddr[index];
vdata->maddr[index] = 0;
if (!mspec_zero_block(my_page, PAGE_SIZE))
uncached_free_page(my_page, 1);
else
printk(KERN_WARNING "mspec_close(): "
"failed to zero page %ld\n", my_page);
}
if (vdata->flags & VMD_VMALLOCED)
vfree(vdata);
else
kfree(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;
BUG_ON(address < vdata->vm_start || address >= vdata->vm_end);
index = (address - vdata->vm_start) >> PAGE_SHIFT;
maddr = (volatile unsigned long) vdata->maddr[index];
if (maddr == 0) {
maddr = uncached_alloc_page(numa_node_id(), 1);
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, 1);
maddr = vdata->maddr[index];
}
spin_unlock(&vdata->lock);
}
if (vdata->type == MSPEC_FETCHOP)
paddr = TO_AMO(maddr);
else
paddr = maddr & ~__IA64_UNCACHED_OFFSET;
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,
enum mspec_page_type type)
{
struct vma_data *vdata;
int pages, vdata_size, flags = 0;
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);
flags = VMD_VMALLOCED;
}
if (!vdata)
return -ENOMEM;
memset(vdata, 0, vdata_size);
vdata->vm_start = vma->vm_start;
vdata->vm_end = vma->vm_end;
vdata->flags = flags;
vdata->type = type;
spin_lock_init(&vdata->lock);
vdata->refcnt = ATOMIC_INIT(1);
vma->vm_private_data = vdata;
vma->vm_flags |= (VM_IO | VM_RESERVED | VM_PFNMAP | VM_DONTEXPAND);
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 const 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 const 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 const 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
*/
#ifdef CONFIG_SGI_SN
if (ia64_platform_is("sn2")) {
is_sn2 = 1;
if (is_shub2()) {
ret = -ENOMEM;
for_each_node_state(nid, N_ONLINE) {
int actual_nid;
int nasid;
unsigned long phys;
scratch_page[nid] = uncached_alloc_page(nid, 1);
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;
}
}
#endif
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], 1);
}
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], 1);
}
}
}
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");
