1 files changed, 39 insertions, 13 deletions

diff --git a/drivers/char/rtc.c b/drivers/char/rtc.c
index ec6b65ec69ea..0c66b802736a 100644
--- a/drivers/char/rtc.c
+++ b/drivers/char/rtc.c
@@ -918,6 +918,31 @@ static const struct file_operations rtc_proc_fops = {
 };
 #endif
 
+static resource_size_t rtc_size;
+
+static struct resource * __init rtc_request_region(resource_size_t size)
+{
+        struct resource *r;
+
+        if (RTC_IOMAPPED)
+                r = request_region(RTC_PORT(0), size, "rtc");
+        else
+                r = request_mem_region(RTC_PORT(0), size, "rtc");
+
+        if (r)
+                rtc_size = size;
+
+        return r;
+}
+
+static void rtc_release_region(void)
+{
+        if (RTC_IOMAPPED)
+                release_region(RTC_PORT(0), rtc_size);
+        else
+                release_mem_region(RTC_PORT(0), rtc_size);
+}
+
 static int __init rtc_init(void)
 {
 #ifdef CONFIG_PROC_FS
@@ -968,10 +993,17 @@ found:
         }
 no_irq:
 #else
-        if (RTC_IOMAPPED)
-                r = request_region(RTC_PORT(0), RTC_IO_EXTENT, "rtc");
-        else
-                r = request_mem_region(RTC_PORT(0), RTC_IO_EXTENT, "rtc");
+        r = rtc_request_region(RTC_IO_EXTENT);
+
+        /*
+         * If we've already requested a smaller range (for example, because
+         * PNPBIOS or ACPI told us how the device is configured), the request
+         * above might fail because it's too big.
+         *
+         * If so, request just the range we actually use.
+         */
+        if (!r)
+                r = rtc_request_region(RTC_IO_EXTENT_USED);
         if (!r) {
 #ifdef RTC_IRQ
                 rtc_has_irq = 0;
@@ -992,10 +1024,7 @@ no_irq:
                 /* Yeah right, seeing as irq 8 doesn't even hit the bus. */
                 rtc_has_irq = 0;
                 printk(KERN_ERR "rtc: IRQ %d is not free.\n", RTC_IRQ);
-                if (RTC_IOMAPPED)
-                        release_region(RTC_PORT(0), RTC_IO_EXTENT);
-                else
-                        release_mem_region(RTC_PORT(0), RTC_IO_EXTENT);
+                rtc_release_region();
                 return -EIO;
         }
         hpet_rtc_timer_init();
@@ -1009,7 +1038,7 @@ no_irq:
                 free_irq(RTC_IRQ, NULL);
                 rtc_has_irq = 0;
 #endif
-                release_region(RTC_PORT(0), RTC_IO_EXTENT);
+                rtc_release_region();
                 return -ENODEV;
         }
 
@@ -1091,10 +1120,7 @@ static void __exit rtc_exit (void)
         if (rtc_has_irq)
                 free_irq (rtc_irq, &rtc_port);
 #else
-        if (RTC_IOMAPPED)
-                release_region(RTC_PORT(0), RTC_IO_EXTENT);
-        else
-                release_mem_region(RTC_PORT(0), RTC_IO_EXTENT);
+        rtc_release_region();
 #ifdef RTC_IRQ
         if (rtc_has_irq)
                 free_irq (RTC_IRQ, NULL);