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m41t94.c
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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 <[email protected]>
*
* 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
*/
}