rtc: mc146818: Set up RTC at start of day
Provide a function to set up the RTC ready for use.
Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/drivers/rtc/mc146818.c b/drivers/rtc/mc146818.c
index f7cf106..39e6041 100644
--- a/drivers/rtc/mc146818.c
+++ b/drivers/rtc/mc146818.c
@@ -14,6 +14,7 @@
#include <common.h>
#include <command.h>
#include <rtc.h>
+#include <version.h>
#if defined(__I386__) || defined(CONFIG_MALTA)
#include <asm/io.h>
@@ -23,6 +24,9 @@
#if defined(CONFIG_CMD_DATE)
+/* Set this to 1 to clear the CMOS RAM */
+#define CLEAR_CMOS 0
+
static uchar rtc_read (uchar reg);
static void rtc_write (uchar reg, uchar val);
@@ -41,7 +45,14 @@
#define RTC_CONFIG_B 0x0B
#define RTC_CONFIG_C 0x0C
#define RTC_CONFIG_D 0x0D
+#define RTC_REG_SIZE 0x80
+
+#define RTC_CONFIG_A_REF_CLCK_32KHZ (1 << 5)
+#define RTC_CONFIG_A_RATE_1024HZ 6
+#define RTC_CONFIG_B_24H (1 << 1)
+
+#define RTC_CONFIG_D_VALID_RAM_AND_TIME 0x80
/* ------------------------------------------------------------------------- */
@@ -128,25 +139,49 @@
*/
static uchar rtc_read (uchar reg)
{
- return(in8(CONFIG_SYS_RTC_REG_BASE_ADDR+reg));
+ return in8(CONFIG_SYS_RTC_REG_BASE_ADDR + reg);
}
static void rtc_write (uchar reg, uchar val)
{
- out8(CONFIG_SYS_RTC_REG_BASE_ADDR+reg, val);
+ out8(CONFIG_SYS_RTC_REG_BASE_ADDR + reg, val);
}
#else
static uchar rtc_read (uchar reg)
{
out8(RTC_PORT_MC146818,reg);
- return(in8(RTC_PORT_MC146818+1));
+ return in8(RTC_PORT_MC146818 + 1);
}
static void rtc_write (uchar reg, uchar val)
{
out8(RTC_PORT_MC146818,reg);
- out8(RTC_PORT_MC146818+1,val);
+ out8(RTC_PORT_MC146818+1, val);
}
#endif
+void rtc_init(void)
+{
+#if CLEAR_CMOS
+ int i;
+
+ rtc_write(RTC_SECONDS_ALARM, 0);
+ rtc_write(RTC_MINUTES_ALARM, 0);
+ rtc_write(RTC_HOURS_ALARM, 0);
+ for (i = RTC_CONFIG_A; i < RTC_REG_SIZE; i++)
+ rtc_write(i, 0);
+ printf("RTC: zeroing CMOS RAM\n");
+#endif
+
+ /* Setup the real time clock */
+ rtc_write(RTC_CONFIG_B, RTC_CONFIG_B_24H);
+ /* Setup the frequency it operates at */
+ rtc_write(RTC_CONFIG_A, RTC_CONFIG_A_REF_CLCK_32KHZ |
+ RTC_CONFIG_A_RATE_1024HZ);
+ /* Ensure all reserved bits are 0 in register D */
+ rtc_write(RTC_CONFIG_D, RTC_CONFIG_D_VALID_RAM_AND_TIME);
+
+ /* Clear any pending interrupts */
+ rtc_read(RTC_CONFIG_C);
+}
#endif