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@xxxxxx>
---
drivers/acpi/osl.c | 128 ++++++++++++++++++++++++++++++++++++++++++++++------
1 files changed, 113 insertions(+), 15 deletions(-)
diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
index 58842fb..bd72129 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;
}
--
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