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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Dallas DS1302 RTC Support
4 *
5 * Copyright (C) 2002 David McCullough
6 * Copyright (C) 2003 - 2007 Paul Mundt
7 */
8
9#include <linux/bcd.h>
10#include <linux/init.h>
11#include <linux/io.h>
12#include <linux/kernel.h>
13#include <linux/module.h>
14#include <linux/of.h>
15#include <linux/rtc.h>
16#include <linux/spi/spi.h>
17
18#define DRV_NAME "rtc-ds1302"
19
20#define RTC_CMD_READ 0x81 /* Read command */
21#define RTC_CMD_WRITE 0x80 /* Write command */
22
23#define RTC_CMD_WRITE_ENABLE 0x00 /* Write enable */
24#define RTC_CMD_WRITE_DISABLE 0x80 /* Write disable */
25
26#define RTC_ADDR_RAM0 0x20 /* Address of RAM0 */
27#define RTC_ADDR_TCR 0x08 /* Address of trickle charge register */
28#define RTC_CLCK_BURST 0x1F /* Address of clock burst */
29#define RTC_CLCK_LEN 0x08 /* Size of clock burst */
30#define RTC_ADDR_CTRL 0x07 /* Address of control register */
31#define RTC_ADDR_YEAR 0x06 /* Address of year register */
32#define RTC_ADDR_DAY 0x05 /* Address of day of week register */
33#define RTC_ADDR_MON 0x04 /* Address of month register */
34#define RTC_ADDR_DATE 0x03 /* Address of day of month register */
35#define RTC_ADDR_HOUR 0x02 /* Address of hour register */
36#define RTC_ADDR_MIN 0x01 /* Address of minute register */
37#define RTC_ADDR_SEC 0x00 /* Address of second register */
38
39static int ds1302_rtc_set_time(struct device *dev, struct rtc_time *time)
40{
41 struct spi_device *spi = dev_get_drvdata(dev);
42 u8 buf[1 + RTC_CLCK_LEN];
43 u8 *bp;
44 int status;
45
46 /* Enable writing */
47 bp = buf;
48 *bp++ = RTC_ADDR_CTRL << 1 | RTC_CMD_WRITE;
49 *bp++ = RTC_CMD_WRITE_ENABLE;
50
51 status = spi_write_then_read(spi, buf, 2,
52 NULL, 0);
53 if (status)
54 return status;
55
56 /* Write registers starting at the first time/date address. */
57 bp = buf;
58 *bp++ = RTC_CLCK_BURST << 1 | RTC_CMD_WRITE;
59
60 *bp++ = bin2bcd(time->tm_sec);
61 *bp++ = bin2bcd(time->tm_min);
62 *bp++ = bin2bcd(time->tm_hour);
63 *bp++ = bin2bcd(time->tm_mday);
64 *bp++ = bin2bcd(time->tm_mon + 1);
65 *bp++ = time->tm_wday + 1;
66 *bp++ = bin2bcd(time->tm_year % 100);
67 *bp++ = RTC_CMD_WRITE_DISABLE;
68
69 /* use write-then-read since dma from stack is nonportable */
70 return spi_write_then_read(spi, buf, sizeof(buf),
71 NULL, 0);
72}
73
74static int ds1302_rtc_get_time(struct device *dev, struct rtc_time *time)
75{
76 struct spi_device *spi = dev_get_drvdata(dev);
77 u8 addr = RTC_CLCK_BURST << 1 | RTC_CMD_READ;
78 u8 buf[RTC_CLCK_LEN - 1];
79 int status;
80
81 /* Use write-then-read to get all the date/time registers
82 * since dma from stack is nonportable
83 */
84 status = spi_write_then_read(spi, &addr, sizeof(addr),
85 buf, sizeof(buf));
86 if (status < 0)
87 return status;
88
89 /* Decode the registers */
90 time->tm_sec = bcd2bin(buf[RTC_ADDR_SEC]);
91 time->tm_min = bcd2bin(buf[RTC_ADDR_MIN]);
92 time->tm_hour = bcd2bin(buf[RTC_ADDR_HOUR]);
93 time->tm_wday = buf[RTC_ADDR_DAY] - 1;
94 time->tm_mday = bcd2bin(buf[RTC_ADDR_DATE]);
95 time->tm_mon = bcd2bin(buf[RTC_ADDR_MON]) - 1;
96 time->tm_year = bcd2bin(buf[RTC_ADDR_YEAR]) + 100;
97
98 return 0;
99}
100
101static const struct rtc_class_ops ds1302_rtc_ops = {
102 .read_time = ds1302_rtc_get_time,
103 .set_time = ds1302_rtc_set_time,
104};
105
106static int ds1302_probe(struct spi_device *spi)
107{
108 struct rtc_device *rtc;
109 u8 addr;
110 u8 buf[4];
111 u8 *bp;
112 int status;
113
114 /* Sanity check board setup data. This may be hooked up
115 * in 3wire mode, but we don't care. Note that unless
116 * there's an inverter in place, this needs SPI_CS_HIGH!
117 */
118 if (spi->bits_per_word && (spi->bits_per_word != 8)) {
119 dev_err(&spi->dev, "bad word length\n");
120 return -EINVAL;
121 } else if (spi->max_speed_hz > 2000000) {
122 dev_err(&spi->dev, "speed is too high\n");
123 return -EINVAL;
124 } else if (spi->mode & SPI_CPHA) {
125 dev_err(&spi->dev, "bad mode\n");
126 return -EINVAL;
127 }
128
129 addr = RTC_ADDR_CTRL << 1 | RTC_CMD_READ;
130 status = spi_write_then_read(spi, &addr, sizeof(addr), buf, 1);
131 if (status < 0) {
132 dev_err(&spi->dev, "control register read error %d\n",
133 status);
134 return status;
135 }
136
137 if ((buf[0] & ~RTC_CMD_WRITE_DISABLE) != 0) {
138 status = spi_write_then_read(spi, &addr, sizeof(addr), buf, 1);
139 if (status < 0) {
140 dev_err(&spi->dev, "control register read error %d\n",
141 status);
142 return status;
143 }
144
145 if ((buf[0] & ~RTC_CMD_WRITE_DISABLE) != 0) {
146 dev_err(&spi->dev, "junk in control register\n");
147 return -ENODEV;
148 }
149 }
150 if (buf[0] == 0) {
151 bp = buf;
152 *bp++ = RTC_ADDR_CTRL << 1 | RTC_CMD_WRITE;
153 *bp++ = RTC_CMD_WRITE_DISABLE;
154
155 status = spi_write_then_read(spi, buf, 2, NULL, 0);
156 if (status < 0) {
157 dev_err(&spi->dev, "control register write error %d\n",
158 status);
159 return status;
160 }
161
162 addr = RTC_ADDR_CTRL << 1 | RTC_CMD_READ;
163 status = spi_write_then_read(spi, &addr, sizeof(addr), buf, 1);
164 if (status < 0) {
165 dev_err(&spi->dev,
166 "error %d reading control register\n",
167 status);
168 return status;
169 }
170
171 if (buf[0] != RTC_CMD_WRITE_DISABLE) {
172 dev_err(&spi->dev, "failed to detect chip\n");
173 return -ENODEV;
174 }
175 }
176
177 spi_set_drvdata(spi, spi);
178
179 rtc = devm_rtc_device_register(&spi->dev, "ds1302",
180 &ds1302_rtc_ops, THIS_MODULE);
181 if (IS_ERR(rtc)) {
182 status = PTR_ERR(rtc);
183 dev_err(&spi->dev, "error %d registering rtc\n", status);
184 return status;
185 }
186
187 return 0;
188}
189
190static int ds1302_remove(struct spi_device *spi)
191{
192 spi_set_drvdata(spi, NULL);
193 return 0;
194}
195
196#ifdef CONFIG_OF
197static const struct of_device_id ds1302_dt_ids[] = {
198 { .compatible = "maxim,ds1302", },
199 { /* sentinel */ }
200};
201MODULE_DEVICE_TABLE(of, ds1302_dt_ids);
202#endif
203
204static struct spi_driver ds1302_driver = {
205 .driver.name = "rtc-ds1302",
206 .driver.of_match_table = of_match_ptr(ds1302_dt_ids),
207 .probe = ds1302_probe,
208 .remove = ds1302_remove,
209};
210
211module_spi_driver(ds1302_driver);
212
213MODULE_DESCRIPTION("Dallas DS1302 RTC driver");
214MODULE_AUTHOR("Paul Mundt, David McCullough");
215MODULE_LICENSE("GPL v2");
1/*
2 * Dallas DS1302 RTC Support
3 *
4 * Copyright (C) 2002 David McCullough
5 * Copyright (C) 2003 - 2007 Paul Mundt
6 *
7 * This file is subject to the terms and conditions of the GNU General Public
8 * License version 2. See the file "COPYING" in the main directory of
9 * this archive for more details.
10 */
11
12#include <linux/bcd.h>
13#include <linux/init.h>
14#include <linux/io.h>
15#include <linux/kernel.h>
16#include <linux/module.h>
17#include <linux/of.h>
18#include <linux/rtc.h>
19#include <linux/spi/spi.h>
20
21#define DRV_NAME "rtc-ds1302"
22
23#define RTC_CMD_READ 0x81 /* Read command */
24#define RTC_CMD_WRITE 0x80 /* Write command */
25
26#define RTC_CMD_WRITE_ENABLE 0x00 /* Write enable */
27#define RTC_CMD_WRITE_DISABLE 0x80 /* Write disable */
28
29#define RTC_ADDR_RAM0 0x20 /* Address of RAM0 */
30#define RTC_ADDR_TCR 0x08 /* Address of trickle charge register */
31#define RTC_CLCK_BURST 0x1F /* Address of clock burst */
32#define RTC_CLCK_LEN 0x08 /* Size of clock burst */
33#define RTC_ADDR_CTRL 0x07 /* Address of control register */
34#define RTC_ADDR_YEAR 0x06 /* Address of year register */
35#define RTC_ADDR_DAY 0x05 /* Address of day of week register */
36#define RTC_ADDR_MON 0x04 /* Address of month register */
37#define RTC_ADDR_DATE 0x03 /* Address of day of month register */
38#define RTC_ADDR_HOUR 0x02 /* Address of hour register */
39#define RTC_ADDR_MIN 0x01 /* Address of minute register */
40#define RTC_ADDR_SEC 0x00 /* Address of second register */
41
42static int ds1302_rtc_set_time(struct device *dev, struct rtc_time *time)
43{
44 struct spi_device *spi = dev_get_drvdata(dev);
45 u8 buf[1 + RTC_CLCK_LEN];
46 u8 *bp;
47 int status;
48
49 /* Enable writing */
50 bp = buf;
51 *bp++ = RTC_ADDR_CTRL << 1 | RTC_CMD_WRITE;
52 *bp++ = RTC_CMD_WRITE_ENABLE;
53
54 status = spi_write_then_read(spi, buf, 2,
55 NULL, 0);
56 if (status)
57 return status;
58
59 /* Write registers starting at the first time/date address. */
60 bp = buf;
61 *bp++ = RTC_CLCK_BURST << 1 | RTC_CMD_WRITE;
62
63 *bp++ = bin2bcd(time->tm_sec);
64 *bp++ = bin2bcd(time->tm_min);
65 *bp++ = bin2bcd(time->tm_hour);
66 *bp++ = bin2bcd(time->tm_mday);
67 *bp++ = bin2bcd(time->tm_mon + 1);
68 *bp++ = time->tm_wday + 1;
69 *bp++ = bin2bcd(time->tm_year % 100);
70 *bp++ = RTC_CMD_WRITE_DISABLE;
71
72 /* use write-then-read since dma from stack is nonportable */
73 return spi_write_then_read(spi, buf, sizeof(buf),
74 NULL, 0);
75}
76
77static int ds1302_rtc_get_time(struct device *dev, struct rtc_time *time)
78{
79 struct spi_device *spi = dev_get_drvdata(dev);
80 u8 addr = RTC_CLCK_BURST << 1 | RTC_CMD_READ;
81 u8 buf[RTC_CLCK_LEN - 1];
82 int status;
83
84 /* Use write-then-read to get all the date/time registers
85 * since dma from stack is nonportable
86 */
87 status = spi_write_then_read(spi, &addr, sizeof(addr),
88 buf, sizeof(buf));
89 if (status < 0)
90 return status;
91
92 /* Decode the registers */
93 time->tm_sec = bcd2bin(buf[RTC_ADDR_SEC]);
94 time->tm_min = bcd2bin(buf[RTC_ADDR_MIN]);
95 time->tm_hour = bcd2bin(buf[RTC_ADDR_HOUR]);
96 time->tm_wday = buf[RTC_ADDR_DAY] - 1;
97 time->tm_mday = bcd2bin(buf[RTC_ADDR_DATE]);
98 time->tm_mon = bcd2bin(buf[RTC_ADDR_MON]) - 1;
99 time->tm_year = bcd2bin(buf[RTC_ADDR_YEAR]) + 100;
100
101 return 0;
102}
103
104static const struct rtc_class_ops ds1302_rtc_ops = {
105 .read_time = ds1302_rtc_get_time,
106 .set_time = ds1302_rtc_set_time,
107};
108
109static int ds1302_probe(struct spi_device *spi)
110{
111 struct rtc_device *rtc;
112 u8 addr;
113 u8 buf[4];
114 u8 *bp;
115 int status;
116
117 /* Sanity check board setup data. This may be hooked up
118 * in 3wire mode, but we don't care. Note that unless
119 * there's an inverter in place, this needs SPI_CS_HIGH!
120 */
121 if (spi->bits_per_word && (spi->bits_per_word != 8)) {
122 dev_err(&spi->dev, "bad word length\n");
123 return -EINVAL;
124 } else if (spi->max_speed_hz > 2000000) {
125 dev_err(&spi->dev, "speed is too high\n");
126 return -EINVAL;
127 } else if (spi->mode & SPI_CPHA) {
128 dev_err(&spi->dev, "bad mode\n");
129 return -EINVAL;
130 }
131
132 addr = RTC_ADDR_CTRL << 1 | RTC_CMD_READ;
133 status = spi_write_then_read(spi, &addr, sizeof(addr), buf, 1);
134 if (status < 0) {
135 dev_err(&spi->dev, "control register read error %d\n",
136 status);
137 return status;
138 }
139
140 if ((buf[0] & ~RTC_CMD_WRITE_DISABLE) != 0) {
141 status = spi_write_then_read(spi, &addr, sizeof(addr), buf, 1);
142 if (status < 0) {
143 dev_err(&spi->dev, "control register read error %d\n",
144 status);
145 return status;
146 }
147
148 if ((buf[0] & ~RTC_CMD_WRITE_DISABLE) != 0) {
149 dev_err(&spi->dev, "junk in control register\n");
150 return -ENODEV;
151 }
152 }
153 if (buf[0] == 0) {
154 bp = buf;
155 *bp++ = RTC_ADDR_CTRL << 1 | RTC_CMD_WRITE;
156 *bp++ = RTC_CMD_WRITE_DISABLE;
157
158 status = spi_write_then_read(spi, buf, 2, NULL, 0);
159 if (status < 0) {
160 dev_err(&spi->dev, "control register write error %d\n",
161 status);
162 return status;
163 }
164
165 addr = RTC_ADDR_CTRL << 1 | RTC_CMD_READ;
166 status = spi_write_then_read(spi, &addr, sizeof(addr), buf, 1);
167 if (status < 0) {
168 dev_err(&spi->dev,
169 "error %d reading control register\n",
170 status);
171 return status;
172 }
173
174 if (buf[0] != RTC_CMD_WRITE_DISABLE) {
175 dev_err(&spi->dev, "failed to detect chip\n");
176 return -ENODEV;
177 }
178 }
179
180 spi_set_drvdata(spi, spi);
181
182 rtc = devm_rtc_device_register(&spi->dev, "ds1302",
183 &ds1302_rtc_ops, THIS_MODULE);
184 if (IS_ERR(rtc)) {
185 status = PTR_ERR(rtc);
186 dev_err(&spi->dev, "error %d registering rtc\n", status);
187 return status;
188 }
189
190 return 0;
191}
192
193static int ds1302_remove(struct spi_device *spi)
194{
195 spi_set_drvdata(spi, NULL);
196 return 0;
197}
198
199#ifdef CONFIG_OF
200static const struct of_device_id ds1302_dt_ids[] = {
201 { .compatible = "maxim,ds1302", },
202 { /* sentinel */ }
203};
204MODULE_DEVICE_TABLE(of, ds1302_dt_ids);
205#endif
206
207static struct spi_driver ds1302_driver = {
208 .driver.name = "rtc-ds1302",
209 .driver.of_match_table = of_match_ptr(ds1302_dt_ids),
210 .probe = ds1302_probe,
211 .remove = ds1302_remove,
212};
213
214module_spi_driver(ds1302_driver);
215
216MODULE_DESCRIPTION("Dallas DS1302 RTC driver");
217MODULE_AUTHOR("Paul Mundt, David McCullough");
218MODULE_LICENSE("GPL v2");