x86/rtc, mrst: Don't register a platform RTC device for for Intel MID platforms

Intel MID x86 platforms have a memory mapped virtual RTC
instead.  No MID platform have the default ports (and
accessing them may do weird stuff).

Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Cc: feng.tang@intel.com
Cc: Feng Tang <feng.tang@intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

2 files changed, 14 insertions, 0 deletions

diff --git a/arch/x86/include/asm/mrst.h b/arch/x86/include/asm/mrst.h
index e6283129c821..93f79094c224 100644
--- a/arch/x86/include/asm/mrst.h
+++ b/arch/x86/include/asm/mrst.h
@@ -31,11 +31,20 @@ enum mrst_cpu_type {
 };
 
 extern enum mrst_cpu_type __mrst_cpu_chip;
+
+#ifdef CONFIG_X86_INTEL_MID
+
 static inline enum mrst_cpu_type mrst_identify_cpu(void)
 {
         return __mrst_cpu_chip;
 }
 
+#else /* !CONFIG_X86_INTEL_MID */
+
+#define mrst_identify_cpu()    (0)
+
+#endif /* !CONFIG_X86_INTEL_MID */
+
 enum mrst_timer_options {
         MRST_TIMER_DEFAULT,
         MRST_TIMER_APBT_ONLY,
diff --git a/arch/x86/kernel/rtc.c b/arch/x86/kernel/rtc.c
index 348ce016a835..af6db6ec5b2a 100644
--- a/arch/x86/kernel/rtc.c
+++ b/arch/x86/kernel/rtc.c
@@ -12,6 +12,7 @@
 #include <asm/vsyscall.h>
 #include <asm/x86_init.h>
 #include <asm/time.h>
+#include <asm/mrst.h>
 
 #ifdef CONFIG_X86_32
 /*
@@ -242,6 +243,10 @@ static __init int add_rtc_cmos(void)
         if (of_have_populated_dt())
                 return 0;
 
+        /* Intel MID platforms don't have ioport rtc */
+        if (mrst_identify_cpu())
+                return -ENODEV;
+
         platform_device_register(&rtc_device);
         dev_info(&rtc_device.dev,
                  "registered platform RTC device (no PNP device found)\n");