1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Analog Devices DS1672 I2C RTC driver
4 *
5 * Copyright 2025 Gateworks Corporation.
6 */
7 #include <dm.h>
8 #include <i2c.h>
9 #include <rtc.h>
10 #include <dm/device_compat.h>
11
12 /* Registers */
13 #define DS1672_REG_CNT_BASE 0
14 #define DS1672_REG_CONTROL 4
15 #define DS1672_REG_TRICKLE 5
16
17 #define DS1672_REG_CONTROL_EOSC 0x80
18
ds1672_read_time(struct udevice * dev,struct rtc_time * tm)19 static int ds1672_read_time(struct udevice *dev, struct rtc_time *tm)
20 {
21 time64_t secs;
22 u8 regs[4];
23 int ret;
24
25 ret = dm_i2c_read(dev, DS1672_REG_CONTROL, regs, 1);
26 if (ret)
27 return ret;
28
29 if (regs[0] & DS1672_REG_CONTROL_EOSC) {
30 dev_err(dev, "Oscillator not enabled. Set time to enable.\n");
31 return -EINVAL;
32 }
33
34 ret = dm_i2c_read(dev, DS1672_REG_CNT_BASE, regs, 4);
35 if (ret)
36 return ret;
37 dev_dbg(dev, "raw read: 0x%02x 0x%02x 0x%02x 0x%02x\n",
38 regs[0], regs[1], regs[2], regs[3]);
39 secs = ((unsigned long)regs[3] << 24) | (regs[2] << 16) | (regs[1] << 8) | regs[0];
40 rtc_to_tm(secs, tm);
41
42 dev_dbg(dev, "read %lld %4d-%02d-%02d (wday=%d) %2d:%02d:%02d\n", secs,
43 tm->tm_year, tm->tm_mon, tm->tm_mday,
44 tm->tm_wday, tm->tm_hour, tm->tm_min, tm->tm_sec);
45
46 return 0;
47 }
48
ds1672_set_time(struct udevice * dev,const struct rtc_time * tm)49 static int ds1672_set_time(struct udevice *dev, const struct rtc_time *tm)
50 {
51 time64_t secs = rtc_mktime(tm);
52 u8 regs[5];
53
54 dev_dbg(dev, "set %4d-%02d-%02d (wday=%d) %2d:%02d:%02d %lld\n",
55 tm->tm_year, tm->tm_mon, tm->tm_mday,
56 tm->tm_wday, tm->tm_hour, tm->tm_min, tm->tm_sec,
57 secs);
58
59 if (tm->tm_year < 2000) {
60 dev_err(dev, "year %d (before 2000) not supported\n",
61 tm->tm_year);
62 return -EINVAL;
63 }
64
65 regs[0] = secs & 0x000000ff;
66 regs[1] = (secs & 0x0000ff00) >> 8;
67 regs[2] = (secs & 0x00ff0000) >> 16;
68 regs[3] = (secs & 0xff000000) >> 24;
69 regs[4] = 0; /* set control reg to enable counting */
70
71 return dm_i2c_write(dev, DS1672_REG_CNT_BASE, regs, 5);
72 }
73
ds1672_reset(struct udevice * dev)74 static int ds1672_reset(struct udevice *dev)
75 {
76 u8 regs[5] = { 0 };
77
78 return dm_i2c_write(dev, DS1672_REG_CNT_BASE, regs, 5);
79 }
80
ds1672_read8(struct udevice * dev,unsigned int reg)81 static int ds1672_read8(struct udevice *dev, unsigned int reg)
82 {
83 return dm_i2c_reg_read(dev, reg);
84 }
85
ds1672_write8(struct udevice * dev,unsigned int reg,int val)86 static int ds1672_write8(struct udevice *dev, unsigned int reg, int val)
87 {
88 return dm_i2c_reg_write(dev, reg, val);
89 }
90
91 static const struct rtc_ops ds1672_rtc_ops = {
92 .get = ds1672_read_time,
93 .set = ds1672_set_time,
94 .reset = ds1672_reset,
95 .read8 = ds1672_read8,
96 .write8 = ds1672_write8,
97 };
98
ds1672_probe(struct udevice * dev)99 static int ds1672_probe(struct udevice *dev)
100 {
101 i2c_set_chip_flags(dev, DM_I2C_CHIP_RD_ADDRESS | DM_I2C_CHIP_WR_ADDRESS);
102
103 return 0;
104 }
105
106 static const struct udevice_id ds1672_of_id[] = {
107 { .compatible = "dallas,ds1672" },
108 { }
109 };
110
111 U_BOOT_DRIVER(rtc_max313xx) = {
112 .name = "rtc-ds1672",
113 .id = UCLASS_RTC,
114 .probe = ds1672_probe,
115 .of_match = ds1672_of_id,
116 .ops = &ds1672_rtc_ops,
117 };
118