diff options
Diffstat (limited to 'c/src/libchip/rtc/mc146818a.c')
-rw-r--r-- | c/src/libchip/rtc/mc146818a.c | 179 |
1 files changed, 179 insertions, 0 deletions
diff --git a/c/src/libchip/rtc/mc146818a.c b/c/src/libchip/rtc/mc146818a.c new file mode 100644 index 0000000000..6fdf1ee228 --- /dev/null +++ b/c/src/libchip/rtc/mc146818a.c @@ -0,0 +1,179 @@ +/* + * This file interfaces with the real-time clock found in + * a Motorola MC146818A (common on PC hardware) + * + * Year 2K Notes: + * + * This chip only uses a two digit field to store the year. This + * code uses the RTEMS Epoch as a pivot year. This lets us map the + * two digit year field as follows: + * + * + two digit years 0-87 are mapped to 2000-2087. + * + two digit years 88-99 are mapped to 1988-1999. + * + * This is less than the time span supported by RTEMS. + * + * COPYRIGHT (c) 1989-1999. + * On-Line Applications Research Corporation (OAR). + * + * The license and distribution terms for this file may be + * found in the file LICENSE in this distribution or at + * http://www.rtems.com/license/LICENSE. + * + * $Id$ + */ +#include <rtems.h> +#include <libchip/rtc.h> +#include <libchip/mc146818a.h> +#include <bsp.h> + +#define From_BCD( _x ) ((((_x) >> 4) * 10) + ((_x) & 0x0F)) +#define To_BCD( _x ) ((((_x) / 10) << 4) + ((_x) % 10)) + +/* + * See if chip is present + */ +boolean rtc_probe( + int minor +) +{ + unsigned32 mc146818a; + getRegister_f getReg; + unsigned32 value; + + /* + * Verify that chip is present and that time is valid + */ + mc146818a = RTC_Table[ minor ].ulCtrlPort1; + getReg = RTC_Table[ minor ].getRegister; + value = (*getReg)( mc146818a, MC146818A_STATUSD ); + if ((value == 0) || (value == 0xFF)) + return FALSE; + return TRUE; +} + +/* + * Initialize chip + */ +void mc146818a_initialize( + int minor +) +{ + unsigned32 mc146818a; + getRegister_f getReg; + setRegister_f setReg; + + mc146818a = RTC_Table[ minor ].ulCtrlPort1; + getReg = RTC_Table[ minor ].getRegister; + setReg = RTC_Table[ minor ].setRegister; + + (*setReg)( mc146818a, MC146818A_STATUSA, MC146818ASA_DIVIDER|MC146818ASA_1024 ); + (*setReg)( mc146818a, MC146818A_STATUSB, MC146818ASB_24HR ); +} + +/* + * Read time from chip + */ +int mc146818a_get_time( + int minor, + rtems_time_of_day *time +) +{ + unsigned32 mc146818a; + getRegister_f getReg; + unsigned32 value; + rtems_interrupt_level level; + + mc146818a = RTC_Table[ minor ].ulCtrlPort1; + getReg = RTC_Table[ minor ].getRegister; + + /* + * No time if power failed + */ + if (((*getReg)( mc146818a, MC146818A_STATUSD ) & MC146818ASD_PWR) == 0) + return -1; + + /* + * Wait for time update to complete + */ + rtems_interrupt_disable( level ); + while (((*getReg)( mc146818a, MC146818A_STATUSA ) & MC146818ASA_TUP) != 0) { + rtems_interrupt_flash( level ); + } + + /* + * Read the time (we have at least 244 usec to do this) + */ + value = (*getReg)( mc146818a, MC146818A_YEAR ); + value = From_BCD( value ); + if ( value < 88 ) + time->year = 2000 + value; + else + time->year = 1900 + value; + + value = (*getReg)( mc146818a, MC146818A_MONTH ); + time->month = From_BCD( value ); + + value = (*getReg)( mc146818a, MC146818A_DAY ); + time->day = From_BCD( value ); + + value = (*getReg)( mc146818a, MC146818A_HRS ); + time->hour = From_BCD( value ); + + value = (*getReg)( mc146818a, MC146818A_MIN ); + time->minute = From_BCD( value ); + + value = (*getReg)( mc146818a, MC146818A_SEC ); + rtems_interrupt_enable( level ); + time->second = From_BCD( value ); + time->ticks = 0; + + return 0; +} + +/* + * Set time into chip + */ +int mc146818a_set_time( + int minor, + rtems_time_of_day *time +) +{ + unsigned32 mc146818a; + getRegister_f getReg; + setRegister_f setReg; + + mc146818a = RTC_Table[ minor ].ulCtrlPort1; + getReg = RTC_Table[ minor ].getRegister; + setReg = RTC_Table[ minor ].setRegister; + + /* + * Stop the RTC + */ + (*setReg)( mc146818a, MC146818A_STATUSB, MC146818ASB_HALT|MC146818ASB_24HR ); + + if ( time->year >= 2088 ) + rtems_fatal_error_occurred( RTEMS_INVALID_NUMBER ); + + (*setReg)( mc146818a, MC146818A_YEAR, To_BCD(time->year % 100) ); + (*setReg)( mc146818a, MC146818A_MONTH, To_BCD(time->month) ); + (*setReg)( mc146818a, MC146818A_DAY, To_BCD(time->day) ); + (*setReg)( mc146818a, MC146818A_HRS, To_BCD(time->hour) ); + (*setReg)( mc146818a, MC146818A_MIN, To_BCD(time->minute) ); + (*setReg)( mc146818a, MC146818A_SEC, To_BCD(time->second) ); + + /* + * Restart the RTC + */ + (*setReg)( mc146818a, MC146818A_STATUSB, MC146818ASB_24HR ); + return 0; +} + +/* + * Driver function table + */ +rtc_fns mc146818a_fns = { + mc146818a_initialize, + mc146818a_get_time, + mc146818a_set_time +}; |