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// SPDX-License-Identifier: GPL-2.0-only
/*
* Analog Devices DS1672 I2C RTC driver
*
* Copyright 2025 Gateworks Corporation.
*/
#include <dm.h>
#include <i2c.h>
#include <rtc.h>
#include <dm/device_compat.h>
/* Registers */
#define DS1672_REG_CNT_BASE 0
#define DS1672_REG_CONTROL 4
#define DS1672_REG_TRICKLE 5
#define DS1672_REG_CONTROL_EOSC 0x80
static int ds1672_read_time(struct udevice *dev, struct rtc_time *tm)
{
time64_t secs;
u8 regs[4];
int ret;
ret = dm_i2c_read(dev, DS1672_REG_CONTROL, regs, 1);
if (ret)
return ret;
if (regs[0] & DS1672_REG_CONTROL_EOSC) {
dev_err(dev, "Oscillator not enabled. Set time to enable.\n");
return -EINVAL;
}
ret = dm_i2c_read(dev, DS1672_REG_CNT_BASE, regs, 4);
if (ret)
return ret;
dev_dbg(dev, "raw read: 0x%02x 0x%02x 0x%02x 0x%02x\n",
regs[0], regs[1], regs[2], regs[3]);
secs = ((unsigned long)regs[3] << 24) | (regs[2] << 16) | (regs[1] << 8) | regs[0];
rtc_to_tm(secs, tm);
dev_dbg(dev, "read %lld %4d-%02d-%02d (wday=%d) %2d:%02d:%02d\n", secs,
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 ds1672_set_time(struct udevice *dev, const struct rtc_time *tm)
{
time64_t secs = rtc_mktime(tm);
u8 regs[5];
dev_dbg(dev, "set %4d-%02d-%02d (wday=%d) %2d:%02d:%02d %lld\n",
tm->tm_year, tm->tm_mon, tm->tm_mday,
tm->tm_wday, tm->tm_hour, tm->tm_min, tm->tm_sec,
secs);
if (tm->tm_year < 2000) {
dev_err(dev, "year %d (before 2000) not supported\n",
tm->tm_year);
return -EINVAL;
}
regs[0] = secs & 0x000000ff;
regs[1] = (secs & 0x0000ff00) >> 8;
regs[2] = (secs & 0x00ff0000) >> 16;
regs[3] = (secs & 0xff000000) >> 24;
regs[4] = 0; /* set control reg to enable counting */
return dm_i2c_write(dev, DS1672_REG_CNT_BASE, regs, 5);
}
static int ds1672_reset(struct udevice *dev)
{
u8 regs[5] = { 0 };
return dm_i2c_write(dev, DS1672_REG_CNT_BASE, regs, 5);
}
static int ds1672_read8(struct udevice *dev, unsigned int reg)
{
return dm_i2c_reg_read(dev, reg);
}
static int ds1672_write8(struct udevice *dev, unsigned int reg, int val)
{
return dm_i2c_reg_write(dev, reg, val);
}
static const struct rtc_ops ds1672_rtc_ops = {
.get = ds1672_read_time,
.set = ds1672_set_time,
.reset = ds1672_reset,
.read8 = ds1672_read8,
.write8 = ds1672_write8,
};
static int ds1672_probe(struct udevice *dev)
{
i2c_set_chip_flags(dev, DM_I2C_CHIP_RD_ADDRESS | DM_I2C_CHIP_WR_ADDRESS);
return 0;
}
static const struct udevice_id ds1672_of_id[] = {
{ .compatible = "dallas,ds1672" },
{ }
};
U_BOOT_DRIVER(rtc_max313xx) = {
.name = "rtc-ds1672",
.id = UCLASS_RTC,
.probe = ds1672_probe,
.of_match = ds1672_of_id,
.ops = &ds1672_rtc_ops,
};
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