soc/intel/broadwell: refactor rtc failure checking

In order to prepare for checking RTC failure in the early boot
paths move the rtc failure calculation to pmutil.c and add a helper
function to determine if failure occurred.

BUG=b:63054105

Change-Id: Ia0a38f00d2a5c7270e24bdd35ecab7fbba1016d4
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://review.coreboot.org/21552
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Subrata Banik <subrata.banik@intel.com>
Reviewed-by: Furquan Shaikh <furquan@google.com>

src/soc/intel/broadwell/include/soc/pm.h

@@ -155,4 +155,7 @@ void disable_gpe(uint32_t mask);
 /* Return the selected ACPI SCI IRQ */
 int acpi_sci_irq(void);
 
+/* Return non-zero when RTC failure happened. */
+int rtc_failure(void);
+
 #endif

src/soc/intel/broadwell/lpc.c

@@ -180,18 +180,7 @@ static void pch_power_options(device_t dev)
 
 static void pch_rtc_init(struct device *dev)
 {
-	u8 reg8;
+	cmos_init(rtc_failure());
-	int rtc_failed;
-
-	reg8 = pci_read_config8(dev, GEN_PMCON_3);
-	rtc_failed = reg8 & RTC_BATTERY_DEAD;
-	if (rtc_failed) {
-		reg8 &= ~RTC_BATTERY_DEAD;
-		pci_write_config8(dev, GEN_PMCON_3, reg8);
-		printk(BIOS_DEBUG, "rtc_failed = 0x%x\n", rtc_failed);
-	}
-
-	cmos_init(rtc_failed);
 }
 
 static const struct reg_script pch_misc_init_script[] = {

src/soc/intel/broadwell/pmutil.c

@@ -446,3 +446,20 @@ int acpi_sci_irq(void)
 	printk(BIOS_DEBUG, "SCI is IRQ%d\n", sci_irq);
 	return sci_irq;
 }
+
+int rtc_failure(void)
+{
+	u8 reg8;
+	int rtc_failed;
+	device_t dev = PCH_DEV_LPC;
+
+	reg8 = pci_read_config8(dev, GEN_PMCON_3);
+	rtc_failed = reg8 & RTC_BATTERY_DEAD;
+	if (rtc_failed) {
+		reg8 &= ~RTC_BATTERY_DEAD;
+		pci_write_config8(dev, GEN_PMCON_3, reg8);
+		printk(BIOS_DEBUG, "rtc_failed = 0x%x\n", rtc_failed);
+	}
+
+	return !!rtc_failed;
+}