x86/platform/intel-mid: Enable RTC on Intel Merrifield

Intel Merrifield has legacy RTC in contrast to the rest on Intel MID
platforms.

Set legacy RTC flag explicitly in architecture initialization code and
allocate interrupt for it.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20170113164355.66161-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/platform/intel-mid/mrfld.c

@@ -91,6 +91,7 @@ static unsigned long __init tangier_calibrate_tsc(void)
 static void __init tangier_arch_setup(void)
 {
 	x86_platform.calibrate_tsc = tangier_calibrate_tsc;
+	x86_platform.legacy.rtc = 1;
 }
 
 /* tangier arch ops */

arch/x86/platform/intel-mid/sfi.c

@@ -41,6 +41,7 @@
 #include <asm/intel_scu_ipc.h>
 #include <asm/apb_timer.h>
 #include <asm/reboot.h>
+#include <asm/time.h>
 
 #define	SFI_SIG_OEM0	"OEM0"
 #define MAX_IPCDEVS	24
@@ -539,8 +540,21 @@ static int __init sfi_parse_devs(struct sfi_table_header *table)
 	return 0;
 }
 
+static int __init intel_mid_legacy_rtc_init(void)
+{
+	struct irq_alloc_info info;
+
+	if (!x86_platform.legacy.rtc)
+		return -ENODEV;
+
+	ioapic_set_alloc_attr(&info, NUMA_NO_NODE, 1, 0);
+	return mp_map_gsi_to_irq(RTC_IRQ, IOAPIC_MAP_ALLOC, &info);
+}
+
 static int __init intel_mid_platform_init(void)
 {
+	intel_mid_legacy_rtc_init();
+
 	sfi_table_parse(SFI_SIG_GPIO, NULL, NULL, sfi_parse_gpio);
 	sfi_table_parse(SFI_SIG_DEVS, NULL, NULL, sfi_parse_devs);
 	return 0;