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>

1 files changed, 113 insertions, 15 deletions

diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
index 58842fb9fd9..bd72129e35f 100644
--- 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;
 }