ACPI: Maintain a list of ACPI memory mapped I/O remappings

For memory mapped I/O (MMIO) remappings, add a list to maintain the
remappings and augment the corresponding mapping and unmapping interface
routines (acpi_os_map_memory() and acpi_os_unmap_memory()) to
dynamically add to, and delete from, the list.

The current ACPI I/O accessing methods - acpi_read() and acpi_write() -
end up calling ioremap() when accessing MMIO.  This prevents use of these
methods within interrupt context (IRQ and/or NMI), since ioremap() may
block to allocate memory.  Maintaining a list of MMIO remappings enables
accesses to such areas from within interrupt context provided they have
been pre-mapped.

Signed-off-by: Myron Stowe <myron.stowe@hp.com>
Signed-off-by: Len Brown <len.brown@intel.com>

diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
index 58842fb9fd90fea28093258a4f499adeeedfb837..bd72129e35f2d06d75f7956dff3eee781e9981c3 100644 (file)
--- a/drivers/acpi/osl.c
+++ b/drivers/acpi/osl.c
@@ -95,6 +95,20 @@ struct acpi_res_list {
 static LIST_HEAD(resource_list_head);
 static DEFINE_SPINLOCK(acpi_res_lock);
 
+/*
+ * This list of permanent mappings is for memory that may be accessed from
+ * interrupt context, where we can't do the ioremap().
+ */
+struct acpi_ioremap {
+       struct list_head list;
+       void __iomem *virt;
+       acpi_physical_address phys;
+       acpi_size size;
+};
+
+static LIST_HEAD(acpi_ioremaps);
+static DEFINE_SPINLOCK(acpi_ioremap_lock);
+
 #define        OSI_STRING_LENGTH_MAX 64        /* arbitrary */
 static char osi_additional_string[OSI_STRING_LENGTH_MAX];
 
@@ -260,29 +274,95 @@ acpi_physical_address __init acpi_os_get_root_pointer(void)
        }
 }
 
+/* Must be called with 'acpi_ioremap_lock' lock held. */
+static void __iomem *
+acpi_map_vaddr_lookup(acpi_physical_address phys, acpi_size size)
+{
+       struct acpi_ioremap *map;
+
+       list_for_each_entry(map, &acpi_ioremaps, list)
+               if (map->phys <= phys &&
+                   phys + size <= map->phys + map->size)
+                       return map->virt + (phys - map->phys);
+
+       return NULL;
+}
+
+/* Must be called with 'acpi_ioremap_lock' lock held. */
+static struct acpi_ioremap *
+acpi_map_lookup_virt(void __iomem *virt, acpi_size size)
+{
+       struct acpi_ioremap *map;
+
+       list_for_each_entry(map, &acpi_ioremaps, list)
+               if (map->virt == virt && map->size == size)
+                       return map;
+
+       return NULL;
+}
+
 void __iomem *__init_refok
 acpi_os_map_memory(acpi_physical_address phys, acpi_size size)
 {
+       struct acpi_ioremap *map;
+       unsigned long flags;
+       void __iomem *virt;
+
        if (phys > ULONG_MAX) {
                printk(KERN_ERR PREFIX "Cannot map memory that high\n");
                return NULL;
        }
-       if (acpi_gbl_permanent_mmap)
-               /*
-               * ioremap checks to ensure this is in reserved space
-               */
-               return ioremap((unsigned long)phys, size);
-       else
+
+       if (!acpi_gbl_permanent_mmap)
                return __acpi_map_table((unsigned long)phys, size);
+
+       map = kzalloc(sizeof(*map), GFP_KERNEL);
+       if (!map)
+               return NULL;
+
+       virt = ioremap(phys, size);
+       if (!virt) {
+               kfree(map);
+               return NULL;
+       }
+
+       INIT_LIST_HEAD(&map->list);
+       map->virt = virt;
+       map->phys = phys;
+       map->size = size;
+
+       spin_lock_irqsave(&acpi_ioremap_lock, flags);
+       list_add_tail(&map->list, &acpi_ioremaps);
+       spin_unlock_irqrestore(&acpi_ioremap_lock, flags);
+
+       return virt;
 }
 EXPORT_SYMBOL_GPL(acpi_os_map_memory);
 
 void __ref acpi_os_unmap_memory(void __iomem *virt, acpi_size size)
 {
-       if (acpi_gbl_permanent_mmap)
-               iounmap(virt);
-       else
+       struct acpi_ioremap *map;
+       unsigned long flags;
+
+       if (!acpi_gbl_permanent_mmap) {
                __acpi_unmap_table(virt, size);
+               return;
+       }
+
+       spin_lock_irqsave(&acpi_ioremap_lock, flags);
+       map = acpi_map_lookup_virt(virt, size);
+       if (!map) {
+               spin_unlock_irqrestore(&acpi_ioremap_lock, flags);
+               printk(KERN_ERR PREFIX "%s: bad address %p\n", __func__, virt);
+               dump_stack();
+               return;
+       }
+
+       list_del(&map->list);
+       spin_unlock_irqrestore(&acpi_ioremap_lock, flags);
+
+       iounmap(map->virt);
+       kfree(map);
 }
 EXPORT_SYMBOL_GPL(acpi_os_unmap_memory);
 
@@ -495,8 +575,16 @@ acpi_os_read_memory(acpi_physical_address phys_addr, u32 * value, u32 width)
 {
        u32 dummy;
        void __iomem *virt_addr;
-
-       virt_addr = ioremap(phys_addr, width / 8);
+       int size = width / 8, unmap = 0;
+       unsigned long flags;
+
+       spin_lock_irqsave(&acpi_ioremap_lock, flags);
+       virt_addr = acpi_map_vaddr_lookup(phys_addr, size);
+       spin_unlock_irqrestore(&acpi_ioremap_lock, flags);
+       if (!virt_addr) {
+               virt_addr = ioremap(phys_addr, size);
+               unmap = 1;
+       }
        if (!value)
                value = &dummy;
 
@@ -514,7 +602,8 @@ acpi_os_read_memory(acpi_physical_address phys_addr, u32 * value, u32 width)
                BUG();
        }
 
-       iounmap(virt_addr);
+       if (unmap)
+               iounmap(virt_addr);
 
        return AE_OK;
 }
@@ -523,8 +612,16 @@ acpi_status
 acpi_os_write_memory(acpi_physical_address phys_addr, u32 value, u32 width)
 {
        void __iomem *virt_addr;
-
-       virt_addr = ioremap(phys_addr, width / 8);
+       int size = width / 8, unmap = 0;
+       unsigned long flags;
+
+       spin_lock_irqsave(&acpi_ioremap_lock, flags);
+       virt_addr = acpi_map_vaddr_lookup(phys_addr, size);
+       spin_unlock_irqrestore(&acpi_ioremap_lock, flags);
+       if (!virt_addr) {
+               virt_addr = ioremap(phys_addr, size);
+               unmap = 1;
+       }
 
        switch (width) {
        case 8:
@@ -540,7 +637,8 @@ acpi_os_write_memory(acpi_physical_address phys_addr, u32 value, u32 width)
                BUG();
        }
 
-       iounmap(virt_addr);
+       if (unmap)
+               iounmap(virt_addr);
 
        return AE_OK;
 }