ACPI: Introduce acpi_os_ioremap()

Commit ca9b600be38c ("ACPI / PM: Make suspend_nvs_save() use
acpi_os_map_memory()") attempted to prevent the code in osl.c and nvs.c
from using different ioremap() variants by making the latter use
acpi_os_map_memory() for mapping the NVS pages.  However, that also
requires acpi_os_unmap_memory() to be used for unmapping them, which
causes synchronize_rcu() to be executed many times in a row
unnecessarily and introduces substantial delays during resume on some
systems.

Instead of using acpi_os_map_memory() for mapping the NVS pages in nvs.c
introduce acpi_os_ioremap() calling ioremap_cache() and make the code in
both osl.c and nvs.c use it.

Reported-by: Jeff Chua <jeff.chua.linux@gmail.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 3 deletions

diff --git a/drivers/acpi/nvs.c b/drivers/acpi/nvs.c
index 54b6ab8040a6..fa5a1df42b79 100644
--- a/drivers/acpi/nvs.c
+++ b/drivers/acpi/nvs.c
@@ -12,6 +12,7 @@
 #include <linux/mm.h>
 #include <linux/slab.h>
 #include <linux/acpi.h>
+#include <linux/acpi_io.h>
 #include <acpi/acpiosxf.h>
 
 /*
@@ -80,7 +81,7 @@ void suspend_nvs_free(void)
                         free_page((unsigned long)entry->data);
                         entry->data = NULL;
                         if (entry->kaddr) {
-                                acpi_os_unmap_memory(entry->kaddr, entry->size);
+                                iounmap(entry->kaddr);
                                 entry->kaddr = NULL;
                         }
                 }
@@ -114,8 +115,8 @@ int suspend_nvs_save(void)
 
         list_for_each_entry(entry, &nvs_list, node)
                 if (entry->data) {
-                        entry->kaddr = acpi_os_map_memory(entry->phys_start,
-                                                          entry->size);
+                        entry->kaddr = acpi_os_ioremap(entry->phys_start,
+                                                    entry->size);
                         if (!entry->kaddr) {
                                 suspend_nvs_free();
                                 return -ENOMEM;