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u-boot/drivers/rtc/ds1307.c
Mark Tomlinson 07c652400d rtc: ds1307: Handle oscillator-stop bit correctly 
The DS1307 driver was originally based on the DS1337 driver. However,
the functionality of the clock set/get functions has diverged. In the
original DS1337 driver, the set/get functions did the following:
  1) Setting the clock ensured the oscillator was enabled.
  2) Getting the clock checked and reset the oscillator-stop flag.
The DS1307 does not have an oscillator-stop flag, but the driver tried
(incorrectly) to emulate this by ensuring the oscillator was running. It
really makes no sense to start a stopped clock without setting it.

This patch makes the DS1307 driver behave like the original DS1337
driver again. For the DS1307 itself, this is just a removal of code,
since there is no oscillator-fail bit to check or reset, and the clock
is started when it is set. Since the DS1307 driver can now also be used
for the DS1337 and DS1340 which do have this bit, add code to handle the
oscillator-stop bit in the same was the original DS1337 driver did --
i.e. report that the oscillator had stopped and clear the flag.

This means that setting the date using the date command (which does both
a get and a set) will now clear the oscillator-stop flag in addition to
setting and starting the clock.

The old-style (non-DM) code has not been updated and will be removed in
a future patch. Note that this older code does not support the DS1337,
as there is a separate driver for this. Also note that the original (DM)
code used the wrong control-register address for the DS1337.

Signed-off-by: Mark Tomlinson <mark.tomlinson@alliedtelesis.co.nz>
2021-10-12 16:49:21 -04:00

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// SPDX-License-Identifier: GPL-2.0+
/*
* (C) Copyright 2001, 2002, 2003
* Wolfgang Denk, DENX Software Engineering, wd@denx.de.
* Keith Outwater, keith_outwater@mvis.com`
* Steven Scholz, steven.scholz@imc-berlin.de
*/
/*
* Date & Time support (no alarms) for Dallas Semiconductor (now Maxim)
* DS1307 and DS1338/9 Real Time Clock (RTC).
*
* based on ds1337.c
*/
#include <common.h>
#include <command.h>
#include <dm.h>
#include <log.h>
#include <rtc.h>
#include <i2c.h>
enum ds_type {
ds_1307,
ds_1337,
ds_1339,
ds_1340,
m41t11,
mcp794xx,
};
/*
* RTC register addresses
*/
#define RTC_SEC_REG_ADDR 0x00
#define RTC_MIN_REG_ADDR 0x01
#define RTC_HR_REG_ADDR 0x02
#define RTC_DAY_REG_ADDR 0x03
#define RTC_DATE_REG_ADDR 0x04
#define RTC_MON_REG_ADDR 0x05
#define RTC_YR_REG_ADDR 0x06
#define RTC_CTL_REG_ADDR 0x07
#define DS1337_CTL_REG_ADDR 0x0e
#define DS1337_STAT_REG_ADDR 0x0f
#define DS1340_STAT_REG_ADDR 0x09
#define RTC_STAT_BIT_OSF 0x80
#define RTC_SEC_BIT_CH 0x80 /* Clock Halt (in Register 0) */
/* DS1307-specific bits */
#define RTC_CTL_BIT_RS0 0x01 /* Rate select 0 */
#define RTC_CTL_BIT_RS1 0x02 /* Rate select 1 */
#define RTC_CTL_BIT_SQWE 0x10 /* Square Wave Enable */
#define RTC_CTL_BIT_OUT 0x80 /* Output Control */
/* DS1337-specific bits */
#define DS1337_CTL_BIT_RS1 0x08 /* Rate select 1 */
#define DS1337_CTL_BIT_RS2 0x10 /* Rate select 2 */
#define DS1337_CTL_BIT_EOSC 0x80 /* Enable Oscillator */
/* DS1340-specific bits */
#define DS1340_SEC_BIT_EOSC 0x80 /* Enable Oscillator */
#define DS1340_CTL_BIT_OUT 0x80 /* Output Control */
/* MCP7941X-specific bits */
#define MCP7941X_BIT_ST 0x80
#define MCP7941X_BIT_VBATEN 0x08
#ifndef CONFIG_DM_RTC
/*---------------------------------------------------------------------*/
#undef DEBUG_RTC
#ifdef DEBUG_RTC
#define DEBUGR(fmt, args...) printf(fmt, ##args)
#else
#define DEBUGR(fmt, args...)
#endif
/*---------------------------------------------------------------------*/
#ifndef CONFIG_SYS_I2C_RTC_ADDR
# define CONFIG_SYS_I2C_RTC_ADDR 0x68
#endif
#if defined(CONFIG_RTC_DS1307) && (CONFIG_SYS_I2C_SPEED > 100000)
# error The DS1307 is specified only up to 100kHz!
#endif
static uchar rtc_read (uchar reg);
static void rtc_write (uchar reg, uchar val);
/*
* Get the current time from the RTC
*/
int rtc_get (struct rtc_time *tmp)
{
int rel = 0;
uchar sec, min, hour, mday, wday, mon, year;
#ifdef CONFIG_RTC_MCP79411
read_rtc:
#endif
sec = rtc_read (RTC_SEC_REG_ADDR);
min = rtc_read (RTC_MIN_REG_ADDR);
hour = rtc_read (RTC_HR_REG_ADDR);
wday = rtc_read (RTC_DAY_REG_ADDR);
mday = rtc_read (RTC_DATE_REG_ADDR);
mon = rtc_read (RTC_MON_REG_ADDR);
year = rtc_read (RTC_YR_REG_ADDR);
DEBUGR ("Get RTC year: %02x mon: %02x mday: %02x wday: %02x "
"hr: %02x min: %02x sec: %02x\n",
year, mon, mday, wday, hour, min, sec);
#ifdef CONFIG_RTC_DS1307
if (sec & RTC_SEC_BIT_CH) {
printf ("### Warning: RTC oscillator has stopped\n");
/* clear the CH flag */
rtc_write (RTC_SEC_REG_ADDR,
rtc_read (RTC_SEC_REG_ADDR) & ~RTC_SEC_BIT_CH);
rel = -1;
}
#endif
#ifdef CONFIG_RTC_MCP79411
/* make sure that the backup battery is enabled */
if (!(wday & MCP7941X_BIT_VBATEN)) {
rtc_write(RTC_DAY_REG_ADDR,
wday | MCP7941X_BIT_VBATEN);
}
/* clock halted? turn it on, so clock can tick. */
if (!(sec & MCP7941X_BIT_ST)) {
rtc_write(RTC_SEC_REG_ADDR, MCP7941X_BIT_ST);
printf("Started RTC\n");
goto read_rtc;
}
#endif
tmp->tm_sec = bcd2bin (sec & 0x7F);
tmp->tm_min = bcd2bin (min & 0x7F);
tmp->tm_hour = bcd2bin (hour & 0x3F);
tmp->tm_mday = bcd2bin (mday & 0x3F);
tmp->tm_mon = bcd2bin (mon & 0x1F);
tmp->tm_year = bcd2bin (year) + ( bcd2bin (year) >= 70 ? 1900 : 2000);
tmp->tm_wday = bcd2bin ((wday - 1) & 0x07);
tmp->tm_yday = 0;
tmp->tm_isdst= 0;
DEBUGR ("Get DATE: %4d-%02d-%02d (wday=%d) TIME: %2d:%02d:%02d\n",
tmp->tm_year, tmp->tm_mon, tmp->tm_mday, tmp->tm_wday,
tmp->tm_hour, tmp->tm_min, tmp->tm_sec);
return rel;
}
/*
* Set the RTC
*/
int rtc_set (struct rtc_time *tmp)
{
DEBUGR ("Set DATE: %4d-%02d-%02d (wday=%d) TIME: %2d:%02d:%02d\n",
tmp->tm_year, tmp->tm_mon, tmp->tm_mday, tmp->tm_wday,
tmp->tm_hour, tmp->tm_min, tmp->tm_sec);
if (tmp->tm_year < 1970 || tmp->tm_year > 2069)
printf("WARNING: year should be between 1970 and 2069!\n");
rtc_write (RTC_YR_REG_ADDR, bin2bcd (tmp->tm_year % 100));
rtc_write (RTC_MON_REG_ADDR, bin2bcd (tmp->tm_mon));
#ifdef CONFIG_RTC_MCP79411
rtc_write (RTC_DAY_REG_ADDR,
bin2bcd (tmp->tm_wday + 1) | MCP7941X_BIT_VBATEN);
#else
rtc_write (RTC_DAY_REG_ADDR, bin2bcd (tmp->tm_wday + 1));
#endif
rtc_write (RTC_DATE_REG_ADDR, bin2bcd (tmp->tm_mday));
rtc_write (RTC_HR_REG_ADDR, bin2bcd (tmp->tm_hour));
rtc_write (RTC_MIN_REG_ADDR, bin2bcd (tmp->tm_min));
#ifdef CONFIG_RTC_MCP79411
rtc_write (RTC_SEC_REG_ADDR, bin2bcd (tmp->tm_sec) | MCP7941X_BIT_ST);
#else
rtc_write (RTC_SEC_REG_ADDR, bin2bcd (tmp->tm_sec));
#endif
return 0;
}
/*
* Reset the RTC. We setting the date back to 1970-01-01.
* We also enable the oscillator output on the SQW/OUT pin and program
* it for 32,768 Hz output. Note that according to the datasheet, turning
* on the square wave output increases the current drain on the backup
* battery to something between 480nA and 800nA.
*/
void rtc_reset (void)
{
rtc_write (RTC_SEC_REG_ADDR, 0x00); /* clearing Clock Halt */
rtc_write (RTC_CTL_REG_ADDR, RTC_CTL_BIT_SQWE | RTC_CTL_BIT_RS1 | RTC_CTL_BIT_RS0);
}
/*
* Helper functions
*/
static
uchar rtc_read (uchar reg)
{
return (i2c_reg_read (CONFIG_SYS_I2C_RTC_ADDR, reg));
}
static void rtc_write (uchar reg, uchar val)
{
i2c_reg_write (CONFIG_SYS_I2C_RTC_ADDR, reg, val);
}
#endif /* !CONFIG_DM_RTC */
#ifdef CONFIG_DM_RTC
static int ds1307_rtc_set(struct udevice *dev, const struct rtc_time *tm)
{
int ret;
uchar buf[7];
enum ds_type type = dev_get_driver_data(dev);
debug("Set DATE: %4d-%02d-%02d (wday=%d) TIME: %2d:%02d:%02d\n",
tm->tm_year, tm->tm_mon, tm->tm_mday, tm->tm_wday,
tm->tm_hour, tm->tm_min, tm->tm_sec);
if (tm->tm_year < 1970 || tm->tm_year > 2069)
printf("WARNING: year should be between 1970 and 2069!\n");
buf[RTC_YR_REG_ADDR] = bin2bcd(tm->tm_year % 100);
buf[RTC_MON_REG_ADDR] = bin2bcd(tm->tm_mon);
buf[RTC_DAY_REG_ADDR] = bin2bcd(tm->tm_wday + 1);
buf[RTC_DATE_REG_ADDR] = bin2bcd(tm->tm_mday);
buf[RTC_HR_REG_ADDR] = bin2bcd(tm->tm_hour);
buf[RTC_MIN_REG_ADDR] = bin2bcd(tm->tm_min);
buf[RTC_SEC_REG_ADDR] = bin2bcd(tm->tm_sec);
if (type == mcp794xx) {
buf[RTC_DAY_REG_ADDR] |= MCP7941X_BIT_VBATEN;
buf[RTC_SEC_REG_ADDR] |= MCP7941X_BIT_ST;
}
ret = dm_i2c_write(dev, 0, buf, sizeof(buf));
if (ret < 0)
return ret;
if (type == ds_1337) {
/* Ensure oscillator is enabled */
dm_i2c_reg_write(dev, DS1337_CTL_REG_ADDR, 0);
}
return 0;
}
static int ds1307_rtc_get(struct udevice *dev, struct rtc_time *tm)
{
int ret;
uchar buf[7];
enum ds_type type = dev_get_driver_data(dev);
ret = dm_i2c_read(dev, 0, buf, sizeof(buf));
if (ret < 0)
return ret;
if (type == ds_1337 || type == ds_1340) {
uint reg = (type == ds_1337) ? DS1337_STAT_REG_ADDR :
DS1340_STAT_REG_ADDR;
int status = dm_i2c_reg_read(dev, reg);
if (status >= 0 && (status & RTC_STAT_BIT_OSF)) {
printf("### Warning: RTC oscillator has stopped\n");
/* clear the OSF flag */
dm_i2c_reg_write(dev, reg, status & ~RTC_STAT_BIT_OSF);
}
}
tm->tm_sec = bcd2bin(buf[RTC_SEC_REG_ADDR] & 0x7F);
tm->tm_min = bcd2bin(buf[RTC_MIN_REG_ADDR] & 0x7F);
tm->tm_hour = bcd2bin(buf[RTC_HR_REG_ADDR] & 0x3F);
tm->tm_mday = bcd2bin(buf[RTC_DATE_REG_ADDR] & 0x3F);
tm->tm_mon = bcd2bin(buf[RTC_MON_REG_ADDR] & 0x1F);
tm->tm_year = bcd2bin(buf[RTC_YR_REG_ADDR]) +
(bcd2bin(buf[RTC_YR_REG_ADDR]) >= 70 ?
1900 : 2000);
tm->tm_wday = bcd2bin((buf[RTC_DAY_REG_ADDR] - 1) & 0x07);
tm->tm_yday = 0;
tm->tm_isdst = 0;
debug("Get DATE: %4d-%02d-%02d (wday=%d) TIME: %2d:%02d:%02d\n",
tm->tm_year, tm->tm_mon, tm->tm_mday, tm->tm_wday,
tm->tm_hour, tm->tm_min, tm->tm_sec);
return 0;
}
static int ds1307_rtc_reset(struct udevice *dev)
{
int ret;
enum ds_type type = dev_get_driver_data(dev);
/*
* reset clock/oscillator in the seconds register:
* on DS1307 bit 7 enables Clock Halt (CH),
* on DS1340 bit 7 disables the oscillator (not EOSC)
* on MCP794xx bit 7 enables Start Oscillator (ST)
*/
ret = dm_i2c_reg_write(dev, RTC_SEC_REG_ADDR, 0x00);
if (ret < 0)
return ret;
if (type == ds_1307) {
/* Write control register in order to enable square-wave
* output (SQWE) and set a default rate of 32.768kHz (RS1|RS0).
*/
ret = dm_i2c_reg_write(dev, RTC_CTL_REG_ADDR,
RTC_CTL_BIT_SQWE | RTC_CTL_BIT_RS1 |
RTC_CTL_BIT_RS0);
} else if (type == ds_1337) {
/* Write control register in order to enable oscillator output
* (not EOSC) and set a default rate of 32.768kHz (RS2|RS1).
*/
ret = dm_i2c_reg_write(dev, DS1337_CTL_REG_ADDR,
DS1337_CTL_BIT_RS2 | DS1337_CTL_BIT_RS1);
} else if (type == ds_1340 || type == mcp794xx || type == m41t11) {
/* Reset clock calibration, frequency test and output level. */
ret = dm_i2c_reg_write(dev, RTC_CTL_REG_ADDR, 0x00);
}
return ret;
}
static int ds1307_probe(struct udevice *dev)
{
i2c_set_chip_flags(dev, DM_I2C_CHIP_RD_ADDRESS |
DM_I2C_CHIP_WR_ADDRESS);
return 0;
}
static const struct rtc_ops ds1307_rtc_ops = {
.get = ds1307_rtc_get,
.set = ds1307_rtc_set,
.reset = ds1307_rtc_reset,
};
static const struct udevice_id ds1307_rtc_ids[] = {
{ .compatible = "dallas,ds1307", .data = ds_1307 },
{ .compatible = "dallas,ds1337", .data = ds_1337 },
{ .compatible = "dallas,ds1339", .data = ds_1339 },
{ .compatible = "dallas,ds1340", .data = ds_1340 },
{ .compatible = "microchip,mcp7941x", .data = mcp794xx },
{ .compatible = "st,m41t11", .data = m41t11 },
{ }
};
U_BOOT_DRIVER(rtc_ds1307) = {
.name = "rtc-ds1307",
.id = UCLASS_RTC,
.probe = ds1307_probe,
.of_match = ds1307_rtc_ids,
.ops = &ds1307_rtc_ops,
};
#endif /* CONFIG_DM_RTC */
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