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bootloader/u-boot_2015_04/drivers/rtc/m41t94.c 3.14 KB
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  /*
   * Driver for ST M41T94 SPI RTC
   *
   * Taken from the Linux kernel drivier:
   * Copyright (C) 2008 Kim B. Heino
   *
   * Adaptation for U-Boot:
   * Copyright (C) 2009
   * Albin Tonnerre, Free Electrons <albin.tonnerre@free-electrons.com>
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 as
   * published by the Free Software Foundation.
   */
  
  #include <common.h>
  #include <rtc.h>
  #include <spi.h>
  
  static struct spi_slave *slave;
  
  #define M41T94_REG_SECONDS	0x01
  #define M41T94_REG_MINUTES	0x02
  #define M41T94_REG_HOURS	0x03
  #define M41T94_REG_WDAY		0x04
  #define M41T94_REG_DAY		0x05
  #define M41T94_REG_MONTH	0x06
  #define M41T94_REG_YEAR		0x07
  #define M41T94_REG_HT		0x0c
  
  #define M41T94_BIT_HALT		0x40
  #define M41T94_BIT_STOP		0x80
  #define M41T94_BIT_CB		0x40
  #define M41T94_BIT_CEB		0x80
  
  int rtc_set(struct rtc_time *tm)
  {
  	u8 buf[8]; /* write cmd + 7 registers */
  	int ret;
  
  	if (!slave) {
  		slave = spi_setup_slave(CONFIG_M41T94_SPI_BUS,
  					CONFIG_M41T94_SPI_CS, 1000000,
  					SPI_MODE_3);
  		if (!slave)
  			return -1;
  	}
  	spi_claim_bus(slave);
  
  	buf[0] = 0x80 | M41T94_REG_SECONDS; /* write time + date */
  	buf[M41T94_REG_SECONDS] = bin2bcd(tm->tm_sec);
  	buf[M41T94_REG_MINUTES] = bin2bcd(tm->tm_min);
  	buf[M41T94_REG_HOURS]   = bin2bcd(tm->tm_hour);
  	buf[M41T94_REG_WDAY]    = bin2bcd(tm->tm_wday + 1);
  	buf[M41T94_REG_DAY]     = bin2bcd(tm->tm_mday);
  	buf[M41T94_REG_MONTH]   = bin2bcd(tm->tm_mon + 1);
  
  	buf[M41T94_REG_HOURS] |= M41T94_BIT_CEB;
  	if (tm->tm_year >= 100)
  		buf[M41T94_REG_HOURS] |= M41T94_BIT_CB;
  	buf[M41T94_REG_YEAR] = bin2bcd(tm->tm_year % 100);
  
  	ret = spi_xfer(slave, 64, buf, NULL, SPI_XFER_BEGIN | SPI_XFER_END);
  	spi_release_bus(slave);
  	return ret;
  }
  
  int rtc_get(struct rtc_time *tm)
  {
  	u8 buf[2];
  	int ret, hour;
  
  	if (!slave) {
  		slave = spi_setup_slave(CONFIG_M41T94_SPI_BUS,
  					CONFIG_M41T94_SPI_CS, 1000000,
  					SPI_MODE_3);
  		if (!slave)
  			return -1;
  	}
  	spi_claim_bus(slave);
  
  	/* clear halt update bit */
  	ret = spi_w8r8(slave, M41T94_REG_HT);
  	if (ret < 0)
  		return ret;
  	if (ret & M41T94_BIT_HALT) {
  		buf[0] = 0x80 | M41T94_REG_HT;
  		buf[1] = ret & ~M41T94_BIT_HALT;
  		spi_xfer(slave, 16, buf, NULL, SPI_XFER_BEGIN | SPI_XFER_END);
  	}
  
  	/* clear stop bit */
  	ret = spi_w8r8(slave, M41T94_REG_SECONDS);
  	if (ret < 0)
  		return ret;
  	if (ret & M41T94_BIT_STOP) {
  		buf[0] = 0x80 | M41T94_REG_SECONDS;
  		buf[1] = ret & ~M41T94_BIT_STOP;
  		spi_xfer(slave, 16, buf, NULL, SPI_XFER_BEGIN | SPI_XFER_END);
  	}
  
  	tm->tm_sec  = bcd2bin(spi_w8r8(slave, M41T94_REG_SECONDS));
  	tm->tm_min  = bcd2bin(spi_w8r8(slave, M41T94_REG_MINUTES));
  	hour = spi_w8r8(slave, M41T94_REG_HOURS);
  	tm->tm_hour = bcd2bin(hour & 0x3f);
  	tm->tm_wday = bcd2bin(spi_w8r8(slave, M41T94_REG_WDAY)) - 1;
  	tm->tm_mday = bcd2bin(spi_w8r8(slave, M41T94_REG_DAY));
  	tm->tm_mon  = bcd2bin(spi_w8r8(slave, M41T94_REG_MONTH)) - 1;
  	tm->tm_year = bcd2bin(spi_w8r8(slave, M41T94_REG_YEAR));
  	if ((hour & M41T94_BIT_CB) || !(hour & M41T94_BIT_CEB))
  		tm->tm_year += 100;
  
  	spi_release_bus(slave);
  	return 0;
  }
  
  void rtc_reset(void)
  {
  	/*
  	 * Could not be tested as the reset pin is not wired on
  	 * the sbc35-ag20 board
  	 */
  }