/*
* atomicio.c - ACPI IO memory pre-mapping/post-unmapping, then
* accessing in atomic context.
*
* This is used for NMI handler to access IO memory area, because
* ioremap/iounmap can not be used in NMI handler. The IO memory area
* is pre-mapped in process context and accessed in NMI handler.
*
* Copyright (C) 2009-2010, Intel Corp.
* Author: Huang Ying <ying.huang@intel.com>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License version
* 2 as published by the Free Software Foundation.
*
* 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/module.h>
#include <linux/init.h>
#include <linux/acpi.h>
#include <linux/io.h>
#include <linux/kref.h>
#include <linux/rculist.h>
#include <linux/interrupt.h>
#include <linux/slab.h>
#include <acpi/atomicio.h>
#define ACPI_PFX "ACPI: "
static LIST_HEAD(acpi_iomaps);
/*
* Used for mutual exclusion between writers of acpi_iomaps list, for
* synchronization between readers and writer, RCU is used.
*/
static DEFINE_SPINLOCK(acpi_iomaps_lock);
struct acpi_iomap {
struct list_head list;
void __iomem *vaddr;
unsigned long size;
phys_addr_t paddr;
struct kref ref;
};
/* acpi_iomaps_lock or RCU read lock must be held before calling */
static struct acpi_iomap *__acpi_find_iomap(phys_addr_t paddr,
unsigned long size)
{
struct acpi_iomap *map;
list_for_each_entry_rcu(map, &acpi_iomaps, list) {
if (map->paddr + map->size >= paddr + size &&
map->paddr <= paddr)
return map;
}
return NULL;
}
/*
* Atomic "ioremap" used by NMI handler, if the specified IO memory
* area is not pre-mapped, NULL will be returned.
*
* acpi_iomaps_lock or RCU read lock must be held before calling
*/
static void __iomem *__acpi_ioremap_fast(phys_addr_t paddr,
unsigned long size)
{
struct acpi_iomap *map;
map = __acpi_find_iomap(paddr, size);
if (map)
return map->vaddr + (paddr - map->paddr);
else
return NULL;
}
/* acpi_iomaps_lock must be held before calling */
static void __iomem *__acpi_try_ioremap(phys_addr_t paddr,
unsigned long size)
{
struct acpi_iomap *map;
map = __acpi_find_iomap(paddr, size);
if (map) {
kref_get(&map->ref);
return map->vaddr + (paddr - map->paddr);
} else
return NULL;
}
/*
* Used to pre-map the specified IO memory area. First try to find
* whether the area is already pre-mapped, if it is, increase the
* reference count (in __acpi_try_ioremap) and return; otherwise, do
* the real ioremap, and add the mapping into acpi_iomaps list.
*/
static void __iomem *acpi_pre_map(phys_addr_t paddr,
unsigned long size)
{
void __iomem *vaddr;
struct acpi_iomap *map;
unsigned long pg_sz, flags;
phys_addr_t pg_off;
spin_lock_irqsave(&acpi_iomaps_lock, flags);
vaddr = __acpi_try_ioremap(paddr, size);
spin_unlock_irqrestore(&acpi_iomaps_lock, flags);
if (vaddr)
return vaddr;
pg_off = paddr & PAGE_MASK;
pg_sz = ((paddr + size + PAGE_SIZE - 1) & PAGE_MASK) - pg_off;
vaddr = ioremap(pg_off, pg_sz);
if (!vaddr)
return NULL;
map = kmalloc(sizeof(*map), GFP_KERNEL);
if (!map)
goto err_unmap;
INIT_LIST_HEAD(&map->list);
map->paddr = pg_off;
map->size = pg_sz;
map->vaddr = vaddr;
kref_init(&map->ref);
spin_lock_irqsave(&acpi_iomaps_lock, flags);
vaddr = __acpi_try_ioremap(paddr, size);
if (vaddr) {
spin_unlock_irqrestore(&acpi_iomaps_lock, flags);
iounmap(map->vaddr);
kfree(map);
return vaddr;
}
list_add_tail_rcu(&map->list, &acpi_iomaps);
spin_unlock_irqrestore(&acpi_iomaps_lock, flags);
return vaddr + (paddr - pg_off);
err_unmap:
iounmap(vaddr);
return NULL;
}
/* acpi_iomaps_lock must be held before calling */
static void __acpi_kref_del_iomap(struct kref *ref)
{
struct acpi_iomap *map;
map = container_of(ref, struct acpi_iomap, ref);
list_del_rcu(&map->list);
}
/*
* Used to post-unmap the specified IO memory area. The iounmap is
* done only if the reference count goes zero.
*/
static void acpi_post_unmap(phys_addr_t paddr, unsigned long size)
{
struct acpi_iomap *map;
unsigned long flags;
int del;
spin_lock_irqsave(&acpi_iomaps_lock, flags);
map = __acpi_find_iomap(paddr, size);
BUG_ON(!map);
del = kref_put(&map->ref, __acpi_kref_del_iomap);
spin_unlock_irqrestore(&acpi_iomaps_lock, flags);
if (!del)
return;
synchronize_rcu();
iounmap(map->vaddr);
kfree(map);
}
/* In NMI handler, should set silent = 1 */
static int acpi_check_gar(struct acpi_generic_address *reg,
u64 *paddr, int silent)
{
u32 width, space_id;
width = reg->bit_width;
space_id = reg->space_id;
/* Handle possible alignment issues */
memcpy(paddr, ®->address, sizeof(*paddr));
if (!*paddr) {
if (!silent)
pr_warning(FW_BUG ACPI_PFX
"Invalid physical address in GAR [0x%llx/%u/%u]\n",
*paddr, width, space_id);
return -EINVAL;
}
if ((width != 8) && (width != 16) && (width != 32) && (width != 64)) {
if (!silent)
pr_warning(FW_BUG ACPI_PFX
"Invalid bit width in GAR [0x%llx/%u/%u]\n",
*paddr, width, space_id);
return -EINVAL;
}
if (space_id != ACPI_ADR_SPACE_SYSTEM_MEMORY &&
space_id != ACPI_ADR_SPACE_SYSTEM_IO) {
if (!silent)
pr_warning(FW_BUG ACPI_PFX
"Invalid address space type in GAR [0x%llx/%u/%u]\n",
*paddr, width, space_id);
return -EINVAL;
}
return 0;
}
/* Pre-map, working on GAR */
int acpi_pre_map_gar(struct acpi_generic_address *reg)
{
u64 paddr;
void __iomem *vaddr;
int rc;
if (reg->space_id != ACPI_ADR_SPACE_SYSTEM_MEMORY)
return 0;
rc = acpi_check_gar(reg, &paddr, 0);
if (rc)
return rc;
vaddr = acpi_pre_map(paddr, reg->bit_width / 8);
if (!vaddr)
return -EIO;
return 0;
}
EXPORT_SYMBOL_GPL(acpi_pre_map_gar);
/* Post-unmap, working on GAR */
int acpi_post_unmap_gar(struct acpi_generic_address *reg)
{
u64 paddr;
int rc;
if (reg->space_id != ACPI_ADR_SPACE_SYSTEM_MEMORY)
return 0;
rc = acpi_check_gar(reg, &paddr, 0);
if (rc)
return rc;
acpi_post_unmap(paddr, reg->bit_width / 8);
return 0;
}
EXPORT_SYMBOL_GPL(acpi_post_unmap_gar);
/*
* Can be used in atomic (including NMI) or process context. RCU read
* lock can only be released after the IO memory area accessing.
*/
static int acpi_atomic_read_mem(u64 paddr, u64 *val, u32 width)
{
void __iomem *addr;
rcu_read_lock();
addr = __acpi_ioremap_fast(paddr, width);
switch (width) {
case 8:
*val = readb(addr);
break;
case 16:
*val = readw(addr);
break;
case 32:
*val = readl(addr);
break;
case 64:
*val = readq(addr);
break;
default:
return -EINVAL;
}
rcu_read_unlock();
return 0;
}
static int acpi_atomic_write_mem(u64 paddr, u64 val, u32 width)
{
void __iomem *addr;
rcu_read_lock();
addr = __acpi_ioremap_fast(paddr, width);
switch (width) {
case 8:
writeb(val, addr);
break;
case 16:
writew(val, addr);
break;
case 32:
writel(val, addr);
break;
case 64:
writeq(val, addr);
break;
default:
return -EINVAL;
}
rcu_read_unlock();
return 0;
}
/* GAR accessing in atomic (including NMI) or process context */
int acpi_atomic_read(u64 *val, struct acpi_generic_address *reg)
{
u64 paddr;
int rc;
rc = acpi_check_gar(reg, &paddr, 1);
if (rc)
return rc;
*val = 0;
switch (reg->space_id) {
case ACPI_ADR_SPACE_SYSTEM_MEMORY:
return acpi_atomic_read_mem(paddr, val, reg->bit_width);
case ACPI_ADR_SPACE_SYSTEM_IO:
return acpi_os_read_port(paddr, (u32 *)val, reg->bit_width);
default:
return -EINVAL;
}
}
EXPORT_SYMBOL_GPL(acpi_atomic_read);
int acpi_atomic_write(u64 val, struct acpi_generic_address *reg)
{
u64 paddr;
int rc;
rc = acpi_check_gar(reg, &paddr, 1);
if (rc)
return rc;
switch (reg->space_id) {
case ACPI_ADR_SPACE_SYSTEM_MEMORY:
return acpi_atomic_write_mem(paddr, val, reg->bit_width);
case ACPI_ADR_SPACE_SYSTEM_IO:
return acpi_os_write_port(paddr, val, reg->bit_width);
default:
return -EINVAL;
}
}
EXPORT_SYMBOL_GPL(acpi_atomic_write);
