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kernel/linux-imx6_3.14.28/arch/arm/mach-footbridge/isa-rtc.c 1.2 KB
6b13f685e   김민수   BSP 최초 추가
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  /*
   *  arch/arm/mach-footbridge/isa-rtc.c
   *
   *  Copyright (C) 1998 Russell King.
   *  Copyright (C) 1998 Phil Blundell
   *
   * CATS has a real-time clock, though the evaluation board doesn't.
   *
   * Changelog:
   *  21-Mar-1998	RMK	Created
   *  27-Aug-1998	PJB	CATS support
   *  28-Dec-1998	APH	Made leds optional
   *  20-Jan-1999	RMK	Started merge of EBSA285, CATS and NetWinder
   *  16-Mar-1999	RMK	More support for EBSA285-like machines with RTCs in
   */
  
  #define RTC_PORT(x)		(0x70+(x))
  #define RTC_ALWAYS_BCD		0
  
  #include <linux/init.h>
  #include <linux/mc146818rtc.h>
  #include <linux/bcd.h>
  #include <linux/io.h>
  
  #include "common.h"
  
  void __init isa_rtc_init(void)
  {
  	int reg_d, reg_b;
  
  	/*
  	 * Probe for the RTC.
  	 */
  	reg_d = CMOS_READ(RTC_REG_D);
  
  	/*
  	 * make sure the divider is set
  	 */
  	CMOS_WRITE(RTC_REF_CLCK_32KHZ, RTC_REG_A);
  
  	/*
  	 * Set control reg B
  	 *   (24 hour mode, update enabled)
  	 */
  	reg_b = CMOS_READ(RTC_REG_B) & 0x7f;
  	reg_b |= 2;
  	CMOS_WRITE(reg_b, RTC_REG_B);
  
  	if ((CMOS_READ(RTC_REG_A) & 0x7f) == RTC_REF_CLCK_32KHZ &&
  	    CMOS_READ(RTC_REG_B) == reg_b) {
  		/*
  		 * We have a RTC.  Check the battery
  		 */
  		if ((reg_d & 0x80) == 0)
  			printk(KERN_WARNING "RTC: *** warning: CMOS battery bad
  ");
  	}
  }