drivers/pc80/mc146818rtc: Reduce superfluous preprocessor use

cmos_init() had layers of preprocessor directives, which resulted in
a complete mess. Refactor it to make use of the IS_ENABLED() macro.
This improves readability significantly.

One of the changes is to remove in inline stub declaration of
(get|set)_option. Although that provided the ability for the compiler
to optimize out code when USE_OPTION_TABLE is not selected, there is
no evidence that such savings are measureable.

Change-Id: I07f00084d809adbb55031b2079f71136ade3028e
Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
Reviewed-on: http://review.coreboot.org/8306
Tested-by: build bot (Jenkins)
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>

src/drivers/pc80/Makefile.inc

@@ -7,9 +7,7 @@ ramstage-$(CONFIG_UDELAY_IO) += udelay_io.c
 ramstage-y += keyboard.c
 ramstage-$(CONFIG_SPKMODEM) += spkmodem.c
 
-ifeq ($(CONFIG_DRIVERS_MC146818),y)
+romstage-$(CONFIG_DRIVERS_MC146818) += mc146818rtc_early.c
-romstage-$(CONFIG_USE_OPTION_TABLE) += mc146818rtc_early.c
-endif
 
 romstage-$(CONFIG_LPC_TPM) += tpm.c
 romstage-$(CONFIG_SPKMODEM) += spkmodem.c

src/drivers/pc80/mc146818rtc.c

@@ -26,9 +26,15 @@
 #include <boot/coreboot_tables.h>
 #include <rtc.h>
 #include <string.h>
+#include <cbfs.h>
+
+/* There's no way around this include guard. option_table.h is autogenerated */
 #if CONFIG_USE_OPTION_TABLE
 #include "option_table.h"
-#include <cbfs.h>
+#else
+#define LB_CKS_RANGE_START	0
+#define LB_CKS_RANGE_END	0
+#define LB_CKS_LOC		0
 #endif
 
 
@@ -48,7 +54,6 @@ static void cmos_reset_date(void)
 	rtc_set(&time);
 }
 
-#if CONFIG_USE_OPTION_TABLE
 static int cmos_checksum_valid(int range_start, int range_end, int cks_loc)
 {
 	int i;
@@ -71,19 +76,18 @@ static void cmos_set_checksum(int range_start, int range_end, int cks_loc)
 	cmos_write(((sum >> 8) & 0x0ff), cks_loc);
 	cmos_write(((sum >> 0) & 0x0ff), cks_loc + 1);
 }
-#endif
 
 #define RTC_CONTROL_DEFAULT (RTC_24H)
 #define RTC_FREQ_SELECT_DEFAULT (RTC_REF_CLCK_32KHZ | RTC_RATE_1024HZ)
 
 #ifndef __SMM__
-void cmos_init(int invalid)
+void cmos_init(bool invalid)
 {
-	int cmos_invalid = 0;
+	bool cmos_invalid = false;
-	int checksum_invalid = 0;
+	bool checksum_invalid = false;
-#if CONFIG_USE_OPTION_TABLE
+	bool clear_cmos;
-	unsigned char x;
+	size_t i;
-#endif
+	uint8_t x;
 
 #ifndef __PRE_RAM__
 	/*
@@ -98,38 +102,37 @@ void cmos_init(int invalid)
 
 	printk(BIOS_DEBUG, "RTC Init\n");
 
-#if CONFIG_USE_OPTION_TABLE
+	if (IS_ENABLED(CONFIG_USE_OPTION_TABLE)) {
 		/* See if there has been a CMOS power problem. */
 		x = cmos_read(RTC_VALID);
 		cmos_invalid = !(x & RTC_VRT);
 
 		/* See if there is a CMOS checksum error */
 		checksum_invalid = !cmos_checksum_valid(PC_CKS_RANGE_START,
-			PC_CKS_RANGE_END,PC_CKS_LOC);
+						PC_CKS_RANGE_END, PC_CKS_LOC);
 
-#define CLEAR_CMOS 0
+		clear_cmos = false;
-#else
+	} else {
-#define CLEAR_CMOS 1
+		clear_cmos = true;
-#endif
+	}
 
 	if (invalid || cmos_invalid || checksum_invalid) {
-#if CLEAR_CMOS
+		if (clear_cmos) {
-		int i;
-
 			cmos_write(0, 0x01);
 			cmos_write(0, 0x03);
 			cmos_write(0, 0x05);
 			for (i = 10; i < 128; i++)
 				cmos_write(0, i);
-#endif
+		}
+
 		if (cmos_invalid)
 			cmos_reset_date();
 
 		printk(BIOS_WARNING, "RTC:%s%s%s%s\n",
-			invalid?" Clear requested":"",
+			invalid ? " Clear requested":"",
-			cmos_invalid?" Power Problem":"",
+			cmos_invalid ? " Power Problem":"",
-			checksum_invalid?" Checksum invalid":"",
+			checksum_invalid ? " Checksum invalid":"",
-			CLEAR_CMOS?" zeroing cmos":"");
+			clear_cmos ? " zeroing cmos":"");
 	}
 
 	/* Setup the real time clock */
@@ -139,7 +142,7 @@ void cmos_init(int invalid)
 	/* Ensure all reserved bits are 0 in register D */
 	cmos_write(RTC_VRT, RTC_VALID);
 
-#if CONFIG_USE_OPTION_TABLE
+	if (IS_ENABLED(CONFIG_USE_OPTION_TABLE)) {
 		/* See if there is a LB CMOS checksum error */
 		checksum_invalid = !cmos_checksum_valid(LB_CKS_RANGE_START,
 				LB_CKS_RANGE_END,LB_CKS_LOC);
@@ -148,15 +151,14 @@ void cmos_init(int invalid)
 
 		/* Make certain we have a valid checksum */
 		cmos_set_checksum(PC_CKS_RANGE_START, PC_CKS_RANGE_END, PC_CKS_LOC);
-#endif
+	}
 
 	/* Clear any pending interrupts */
 	cmos_read(RTC_INTR_FLAGS);
 }
-#endif
+#endif	/* __SMM__ */
 
 
-#if CONFIG_USE_OPTION_TABLE
 /*
  * This routine returns the value of the requested bits.
  * input bit = bit count from the beginning of the cmos image
@@ -200,6 +202,9 @@ enum cb_err get_option(void *dest, const char *name)
 	size_t namelen;
 	int found = 0;
 
+	if (!IS_ENABLED(CONFIG_USE_OPTION_TABLE))
+		return CB_CMOS_OTABLE_DISABLED;
+
 	/* Figure out how long name is */
 	namelen = strnlen(name, CMOS_MAX_NAME_LENGTH);
 
@@ -280,6 +285,9 @@ enum cb_err set_option(const char *name, void *value)
 	size_t namelen;
 	int found = 0;
 
+	if (!IS_ENABLED(CONFIG_USE_OPTION_TABLE))
+		return CB_CMOS_OTABLE_DISABLED;
+
 	/* Figure out how long name is */
 	namelen = strnlen(name, CMOS_MAX_NAME_LENGTH);
 
@@ -318,7 +326,6 @@ enum cb_err set_option(const char *name, void *value)
 
 	return CB_SUCCESS;
 }
-#endif /* CONFIG_USE_OPTION_TABLE */
 
 /*
  * If the CMOS is cleared, the rtc_reg has the invalid date. That

src/include/pc80/mc146818rtc.h

@@ -169,21 +169,13 @@ static inline void cmos_write32(u8 offset, u32 value)
 #endif
 
 #if !defined(__ROMCC__)
-void cmos_init(int invalid);
+void cmos_init(bool invalid);
 void cmos_check_update_date(void);
-#if CONFIG_USE_OPTION_TABLE
+
 enum cb_err set_option(const char *name, void *val);
 enum cb_err get_option(void *dest, const char *name);
 unsigned read_option_lowlevel(unsigned start, unsigned size, unsigned def);
-#else
+
-static inline enum cb_err set_option(const char *name __attribute__((unused)),
-				     void *val __attribute__((unused)))
-				{ return CB_CMOS_OTABLE_DISABLED; };
-static inline enum cb_err get_option(void *dest __attribute__((unused)),
-				     const char *name __attribute__((unused)))
-				{ return CB_CMOS_OTABLE_DISABLED; }
-#define read_option_lowlevel(start, size, def) def
-#endif
 #else /* defined(__ROMCC__) */
 #include <drivers/pc80/mc146818rtc_early.c>
 #endif /* !defined(__ROMCC__) */