[PATCH] Allow reading CMOS day of week register

Someone wanted access to this usually unused (and unused by Linux) value
for the day of week. Existing kernels have the field in the struct but
return 0 always. This updates the kernel to fill in the field. The usual
case of 'not set' conveniently is 0.

Signed-off-by: Alan Cox <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/char/rtc.c

···
  *      1.11a   Daniele Bellucci: Audit create_proc_read_entry in rtc_init
  *	1.12	Venkatesh Pallipadi: Hooks for emulating rtc on HPET base-timer
  *		CONFIG_HPET_EMULATE_RTC
- *
+ *	1.12ac	Alan Cox: Allow read access to the day of week register
  */
 
-#define RTC_VERSION		"1.12"
+#define RTC_VERSION		"1.12ac"
 
 #define RTC_IO_EXTENT	0x8
 
···
 
 	/*
 	 * Only the values that we read from the RTC are set. We leave
-	 * tm_wday, tm_yday and tm_isdst untouched. Even though the
-	 * RTC has RTC_DAY_OF_WEEK, we ignore it, as it is only updated
-	 * by the RTC when initially set to a non-zero value.
+	 * tm_wday, tm_yday and tm_isdst untouched. Note that while the
+	 * RTC has RTC_DAY_OF_WEEK, we should usually ignore it, as it is
+	 * only updated by the RTC when initially set to a non-zero value.
 	 */
 	spin_lock_irq(&rtc_lock);
 	rtc_tm->tm_sec = CMOS_READ(RTC_SECONDS);
···
 	rtc_tm->tm_mday = CMOS_READ(RTC_DAY_OF_MONTH);
 	rtc_tm->tm_mon = CMOS_READ(RTC_MONTH);
 	rtc_tm->tm_year = CMOS_READ(RTC_YEAR);
+	/* Only set from 2.6.16 onwards */
+	rtc_tm->tm_wday = CMOS_READ(RTC_DAY_OF_WEEK);
+
 #ifdef CONFIG_MACH_DECSTATION
 	real_year = CMOS_READ(RTC_DEC_YEAR);
 #endif
···
 		BCD_TO_BIN(rtc_tm->tm_mday);
 		BCD_TO_BIN(rtc_tm->tm_mon);
 		BCD_TO_BIN(rtc_tm->tm_year);
+		BCD_TO_BIN(rtc_tm->tm_wday);
 	}
 
 #ifdef CONFIG_MACH_DECSTATION