361 lines
8.2 KiB
C
361 lines
8.2 KiB
C
/*
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* atomicio.c - ACPI IO memory pre-mapping/post-unmapping, then
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* accessing in atomic context.
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*
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* This is used for NMI handler to access IO memory area, because
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* ioremap/iounmap can not be used in NMI handler. The IO memory area
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* is pre-mapped in process context and accessed in NMI handler.
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*
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* Copyright (C) 2009-2010, Intel Corp.
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* Author: Huang Ying <ying.huang@intel.com>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License version
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* 2 as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/acpi.h>
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#include <linux/io.h>
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#include <linux/kref.h>
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#include <linux/rculist.h>
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#include <linux/interrupt.h>
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#include <acpi/atomicio.h>
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#define ACPI_PFX "ACPI: "
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static LIST_HEAD(acpi_iomaps);
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/*
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* Used for mutual exclusion between writers of acpi_iomaps list, for
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* synchronization between readers and writer, RCU is used.
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*/
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static DEFINE_SPINLOCK(acpi_iomaps_lock);
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struct acpi_iomap {
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struct list_head list;
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void __iomem *vaddr;
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unsigned long size;
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phys_addr_t paddr;
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struct kref ref;
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};
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/* acpi_iomaps_lock or RCU read lock must be held before calling */
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static struct acpi_iomap *__acpi_find_iomap(phys_addr_t paddr,
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unsigned long size)
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{
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struct acpi_iomap *map;
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list_for_each_entry_rcu(map, &acpi_iomaps, list) {
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if (map->paddr + map->size >= paddr + size &&
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map->paddr <= paddr)
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return map;
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}
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return NULL;
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}
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/*
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* Atomic "ioremap" used by NMI handler, if the specified IO memory
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* area is not pre-mapped, NULL will be returned.
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*
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* acpi_iomaps_lock or RCU read lock must be held before calling
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*/
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static void __iomem *__acpi_ioremap_fast(phys_addr_t paddr,
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unsigned long size)
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{
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struct acpi_iomap *map;
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map = __acpi_find_iomap(paddr, size);
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if (map)
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return map->vaddr + (paddr - map->paddr);
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else
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return NULL;
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}
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/* acpi_iomaps_lock must be held before calling */
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static void __iomem *__acpi_try_ioremap(phys_addr_t paddr,
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unsigned long size)
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{
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struct acpi_iomap *map;
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map = __acpi_find_iomap(paddr, size);
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if (map) {
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kref_get(&map->ref);
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return map->vaddr + (paddr - map->paddr);
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} else
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return NULL;
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}
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/*
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* Used to pre-map the specified IO memory area. First try to find
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* whether the area is already pre-mapped, if it is, increase the
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* reference count (in __acpi_try_ioremap) and return; otherwise, do
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* the real ioremap, and add the mapping into acpi_iomaps list.
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*/
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static void __iomem *acpi_pre_map(phys_addr_t paddr,
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unsigned long size)
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{
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void __iomem *vaddr;
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struct acpi_iomap *map;
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unsigned long pg_sz, flags;
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phys_addr_t pg_off;
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spin_lock_irqsave(&acpi_iomaps_lock, flags);
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vaddr = __acpi_try_ioremap(paddr, size);
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spin_unlock_irqrestore(&acpi_iomaps_lock, flags);
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if (vaddr)
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return vaddr;
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pg_off = paddr & PAGE_MASK;
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pg_sz = ((paddr + size + PAGE_SIZE - 1) & PAGE_MASK) - pg_off;
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vaddr = ioremap(pg_off, pg_sz);
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if (!vaddr)
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return NULL;
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map = kmalloc(sizeof(*map), GFP_KERNEL);
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if (!map)
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goto err_unmap;
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INIT_LIST_HEAD(&map->list);
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map->paddr = pg_off;
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map->size = pg_sz;
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map->vaddr = vaddr;
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kref_init(&map->ref);
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spin_lock_irqsave(&acpi_iomaps_lock, flags);
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vaddr = __acpi_try_ioremap(paddr, size);
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if (vaddr) {
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spin_unlock_irqrestore(&acpi_iomaps_lock, flags);
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iounmap(map->vaddr);
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kfree(map);
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return vaddr;
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}
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list_add_tail_rcu(&map->list, &acpi_iomaps);
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spin_unlock_irqrestore(&acpi_iomaps_lock, flags);
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return vaddr + (paddr - pg_off);
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err_unmap:
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iounmap(vaddr);
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return NULL;
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}
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/* acpi_iomaps_lock must be held before calling */
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static void __acpi_kref_del_iomap(struct kref *ref)
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{
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struct acpi_iomap *map;
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map = container_of(ref, struct acpi_iomap, ref);
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list_del_rcu(&map->list);
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}
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/*
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* Used to post-unmap the specified IO memory area. The iounmap is
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* done only if the reference count goes zero.
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*/
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static void acpi_post_unmap(phys_addr_t paddr, unsigned long size)
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{
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struct acpi_iomap *map;
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unsigned long flags;
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int del;
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spin_lock_irqsave(&acpi_iomaps_lock, flags);
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map = __acpi_find_iomap(paddr, size);
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BUG_ON(!map);
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del = kref_put(&map->ref, __acpi_kref_del_iomap);
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spin_unlock_irqrestore(&acpi_iomaps_lock, flags);
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if (!del)
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return;
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synchronize_rcu();
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iounmap(map->vaddr);
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kfree(map);
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}
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/* In NMI handler, should set silent = 1 */
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static int acpi_check_gar(struct acpi_generic_address *reg,
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u64 *paddr, int silent)
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{
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u32 width, space_id;
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width = reg->bit_width;
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space_id = reg->space_id;
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/* Handle possible alignment issues */
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memcpy(paddr, ®->address, sizeof(*paddr));
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if (!*paddr) {
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if (!silent)
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pr_warning(FW_BUG ACPI_PFX
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"Invalid physical address in GAR [0x%llx/%u/%u]\n",
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*paddr, width, space_id);
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return -EINVAL;
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}
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if ((width != 8) && (width != 16) && (width != 32) && (width != 64)) {
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if (!silent)
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pr_warning(FW_BUG ACPI_PFX
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"Invalid bit width in GAR [0x%llx/%u/%u]\n",
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*paddr, width, space_id);
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return -EINVAL;
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}
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if (space_id != ACPI_ADR_SPACE_SYSTEM_MEMORY &&
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space_id != ACPI_ADR_SPACE_SYSTEM_IO) {
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if (!silent)
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pr_warning(FW_BUG ACPI_PFX
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"Invalid address space type in GAR [0x%llx/%u/%u]\n",
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*paddr, width, space_id);
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return -EINVAL;
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}
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return 0;
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}
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/* Pre-map, working on GAR */
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int acpi_pre_map_gar(struct acpi_generic_address *reg)
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{
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u64 paddr;
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void __iomem *vaddr;
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int rc;
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if (reg->space_id != ACPI_ADR_SPACE_SYSTEM_MEMORY)
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return 0;
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rc = acpi_check_gar(reg, &paddr, 0);
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if (rc)
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return rc;
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vaddr = acpi_pre_map(paddr, reg->bit_width / 8);
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if (!vaddr)
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return -EIO;
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return 0;
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}
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EXPORT_SYMBOL_GPL(acpi_pre_map_gar);
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/* Post-unmap, working on GAR */
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int acpi_post_unmap_gar(struct acpi_generic_address *reg)
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{
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u64 paddr;
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int rc;
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if (reg->space_id != ACPI_ADR_SPACE_SYSTEM_MEMORY)
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return 0;
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rc = acpi_check_gar(reg, &paddr, 0);
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if (rc)
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return rc;
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acpi_post_unmap(paddr, reg->bit_width / 8);
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return 0;
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}
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EXPORT_SYMBOL_GPL(acpi_post_unmap_gar);
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/*
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* Can be used in atomic (including NMI) or process context. RCU read
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* lock can only be released after the IO memory area accessing.
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*/
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static int acpi_atomic_read_mem(u64 paddr, u64 *val, u32 width)
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{
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void __iomem *addr;
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rcu_read_lock();
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addr = __acpi_ioremap_fast(paddr, width);
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switch (width) {
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case 8:
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*val = readb(addr);
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break;
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case 16:
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*val = readw(addr);
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break;
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case 32:
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*val = readl(addr);
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break;
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case 64:
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*val = readq(addr);
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break;
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default:
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return -EINVAL;
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}
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rcu_read_unlock();
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return 0;
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}
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static int acpi_atomic_write_mem(u64 paddr, u64 val, u32 width)
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{
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void __iomem *addr;
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rcu_read_lock();
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addr = __acpi_ioremap_fast(paddr, width);
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switch (width) {
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case 8:
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writeb(val, addr);
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break;
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case 16:
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writew(val, addr);
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break;
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case 32:
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writel(val, addr);
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break;
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case 64:
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writeq(val, addr);
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break;
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default:
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return -EINVAL;
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}
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rcu_read_unlock();
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return 0;
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}
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/* GAR accessing in atomic (including NMI) or process context */
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int acpi_atomic_read(u64 *val, struct acpi_generic_address *reg)
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{
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u64 paddr;
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int rc;
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rc = acpi_check_gar(reg, &paddr, 1);
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if (rc)
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return rc;
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*val = 0;
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switch (reg->space_id) {
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case ACPI_ADR_SPACE_SYSTEM_MEMORY:
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return acpi_atomic_read_mem(paddr, val, reg->bit_width);
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case ACPI_ADR_SPACE_SYSTEM_IO:
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return acpi_os_read_port(paddr, (u32 *)val, reg->bit_width);
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default:
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return -EINVAL;
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}
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}
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EXPORT_SYMBOL_GPL(acpi_atomic_read);
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int acpi_atomic_write(u64 val, struct acpi_generic_address *reg)
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{
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u64 paddr;
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int rc;
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rc = acpi_check_gar(reg, &paddr, 1);
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if (rc)
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return rc;
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switch (reg->space_id) {
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case ACPI_ADR_SPACE_SYSTEM_MEMORY:
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return acpi_atomic_write_mem(paddr, val, reg->bit_width);
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case ACPI_ADR_SPACE_SYSTEM_IO:
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return acpi_os_write_port(paddr, val, reg->bit_width);
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default:
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return -EINVAL;
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}
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}
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EXPORT_SYMBOL_GPL(acpi_atomic_write);
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