1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* |
3 | * rtc-ds1390.c -- driver for the Dallas/Maxim DS1390/93/94 SPI RTC |
4 | * |
5 | * Copyright (C) 2008 Mercury IMC Ltd |
6 | * Written by Mark Jackson <mpfj@mimc.co.uk> |
7 | * |
8 | * NOTE: Currently this driver only supports the bare minimum for read |
9 | * and write the RTC. The extra features provided by the chip family |
10 | * (alarms, trickle charger, different control registers) are unavailable. |
11 | */ |
12 | |
13 | #include <linux/init.h> |
14 | #include <linux/module.h> |
15 | #include <linux/platform_device.h> |
16 | #include <linux/rtc.h> |
17 | #include <linux/spi/spi.h> |
18 | #include <linux/bcd.h> |
19 | #include <linux/slab.h> |
20 | #include <linux/of.h> |
21 | |
22 | #define DS1390_REG_100THS 0x00 |
23 | #define DS1390_REG_SECONDS 0x01 |
24 | #define DS1390_REG_MINUTES 0x02 |
25 | #define DS1390_REG_HOURS 0x03 |
26 | #define DS1390_REG_DAY 0x04 |
27 | #define DS1390_REG_DATE 0x05 |
28 | #define DS1390_REG_MONTH_CENT 0x06 |
29 | #define DS1390_REG_YEAR 0x07 |
30 | |
31 | #define DS1390_REG_ALARM_100THS 0x08 |
32 | #define DS1390_REG_ALARM_SECONDS 0x09 |
33 | #define DS1390_REG_ALARM_MINUTES 0x0A |
34 | #define DS1390_REG_ALARM_HOURS 0x0B |
35 | #define DS1390_REG_ALARM_DAY_DATE 0x0C |
36 | |
37 | #define DS1390_REG_CONTROL 0x0D |
38 | #define DS1390_REG_STATUS 0x0E |
39 | #define DS1390_REG_TRICKLE 0x0F |
40 | |
41 | #define DS1390_TRICKLE_CHARGER_ENABLE 0xA0 |
42 | #define DS1390_TRICKLE_CHARGER_250_OHM 0x01 |
43 | #define DS1390_TRICKLE_CHARGER_2K_OHM 0x02 |
44 | #define DS1390_TRICKLE_CHARGER_4K_OHM 0x03 |
45 | #define DS1390_TRICKLE_CHARGER_NO_DIODE 0x04 |
46 | #define DS1390_TRICKLE_CHARGER_DIODE 0x08 |
47 | |
48 | struct ds1390 { |
49 | struct rtc_device *rtc; |
50 | u8 txrx_buf[9]; /* cmd + 8 registers */ |
51 | }; |
52 | |
53 | static void ds1390_set_reg(struct device *dev, unsigned char address, |
54 | unsigned char data) |
55 | { |
56 | struct spi_device *spi = to_spi_device(dev); |
57 | unsigned char buf[2]; |
58 | |
59 | /* MSB must be '1' to write */ |
60 | buf[0] = address | 0x80; |
61 | buf[1] = data; |
62 | |
63 | spi_write(spi, buf, len: 2); |
64 | } |
65 | |
66 | static int ds1390_get_reg(struct device *dev, unsigned char address, |
67 | unsigned char *data) |
68 | { |
69 | struct spi_device *spi = to_spi_device(dev); |
70 | struct ds1390 *chip = dev_get_drvdata(dev); |
71 | int status; |
72 | |
73 | if (!data) |
74 | return -EINVAL; |
75 | |
76 | /* Clear MSB to indicate read */ |
77 | chip->txrx_buf[0] = address & 0x7f; |
78 | /* do the i/o */ |
79 | status = spi_write_then_read(spi, txbuf: chip->txrx_buf, n_tx: 1, rxbuf: chip->txrx_buf, n_rx: 1); |
80 | if (status != 0) |
81 | return status; |
82 | |
83 | *data = chip->txrx_buf[0]; |
84 | |
85 | return 0; |
86 | } |
87 | |
88 | static void ds1390_trickle_of_init(struct spi_device *spi) |
89 | { |
90 | u32 ohms = 0; |
91 | u8 value; |
92 | |
93 | if (of_property_read_u32(np: spi->dev.of_node, propname: "trickle-resistor-ohms" , |
94 | out_value: &ohms)) |
95 | goto out; |
96 | |
97 | /* Enable charger */ |
98 | value = DS1390_TRICKLE_CHARGER_ENABLE; |
99 | if (of_property_read_bool(np: spi->dev.of_node, propname: "trickle-diode-disable" )) |
100 | value |= DS1390_TRICKLE_CHARGER_NO_DIODE; |
101 | else |
102 | value |= DS1390_TRICKLE_CHARGER_DIODE; |
103 | |
104 | /* Resistor select */ |
105 | switch (ohms) { |
106 | case 250: |
107 | value |= DS1390_TRICKLE_CHARGER_250_OHM; |
108 | break; |
109 | case 2000: |
110 | value |= DS1390_TRICKLE_CHARGER_2K_OHM; |
111 | break; |
112 | case 4000: |
113 | value |= DS1390_TRICKLE_CHARGER_4K_OHM; |
114 | break; |
115 | default: |
116 | dev_warn(&spi->dev, |
117 | "Unsupported ohm value %02ux in dt\n" , ohms); |
118 | return; |
119 | } |
120 | |
121 | ds1390_set_reg(dev: &spi->dev, DS1390_REG_TRICKLE, data: value); |
122 | |
123 | out: |
124 | return; |
125 | } |
126 | |
127 | static int ds1390_read_time(struct device *dev, struct rtc_time *dt) |
128 | { |
129 | struct spi_device *spi = to_spi_device(dev); |
130 | struct ds1390 *chip = dev_get_drvdata(dev); |
131 | int status; |
132 | |
133 | /* build the message */ |
134 | chip->txrx_buf[0] = DS1390_REG_SECONDS; |
135 | |
136 | /* do the i/o */ |
137 | status = spi_write_then_read(spi, txbuf: chip->txrx_buf, n_tx: 1, rxbuf: chip->txrx_buf, n_rx: 8); |
138 | if (status != 0) |
139 | return status; |
140 | |
141 | /* The chip sends data in this order: |
142 | * Seconds, Minutes, Hours, Day, Date, Month / Century, Year */ |
143 | dt->tm_sec = bcd2bin(chip->txrx_buf[0]); |
144 | dt->tm_min = bcd2bin(chip->txrx_buf[1]); |
145 | dt->tm_hour = bcd2bin(chip->txrx_buf[2]); |
146 | dt->tm_wday = bcd2bin(chip->txrx_buf[3]); |
147 | dt->tm_mday = bcd2bin(chip->txrx_buf[4]); |
148 | /* mask off century bit */ |
149 | dt->tm_mon = bcd2bin(chip->txrx_buf[5] & 0x7f) - 1; |
150 | /* adjust for century bit */ |
151 | dt->tm_year = bcd2bin(chip->txrx_buf[6]) + ((chip->txrx_buf[5] & 0x80) ? 100 : 0); |
152 | |
153 | return 0; |
154 | } |
155 | |
156 | static int ds1390_set_time(struct device *dev, struct rtc_time *dt) |
157 | { |
158 | struct spi_device *spi = to_spi_device(dev); |
159 | struct ds1390 *chip = dev_get_drvdata(dev); |
160 | |
161 | /* build the message */ |
162 | chip->txrx_buf[0] = DS1390_REG_SECONDS | 0x80; |
163 | chip->txrx_buf[1] = bin2bcd(dt->tm_sec); |
164 | chip->txrx_buf[2] = bin2bcd(dt->tm_min); |
165 | chip->txrx_buf[3] = bin2bcd(dt->tm_hour); |
166 | chip->txrx_buf[4] = bin2bcd(dt->tm_wday); |
167 | chip->txrx_buf[5] = bin2bcd(dt->tm_mday); |
168 | chip->txrx_buf[6] = bin2bcd(dt->tm_mon + 1) | |
169 | ((dt->tm_year > 99) ? 0x80 : 0x00); |
170 | chip->txrx_buf[7] = bin2bcd(dt->tm_year % 100); |
171 | |
172 | /* do the i/o */ |
173 | return spi_write_then_read(spi, txbuf: chip->txrx_buf, n_tx: 8, NULL, n_rx: 0); |
174 | } |
175 | |
176 | static const struct rtc_class_ops ds1390_rtc_ops = { |
177 | .read_time = ds1390_read_time, |
178 | .set_time = ds1390_set_time, |
179 | }; |
180 | |
181 | static int ds1390_probe(struct spi_device *spi) |
182 | { |
183 | unsigned char tmp; |
184 | struct ds1390 *chip; |
185 | int res; |
186 | |
187 | spi->mode = SPI_MODE_3; |
188 | spi->bits_per_word = 8; |
189 | spi_setup(spi); |
190 | |
191 | chip = devm_kzalloc(dev: &spi->dev, size: sizeof(*chip), GFP_KERNEL); |
192 | if (!chip) |
193 | return -ENOMEM; |
194 | |
195 | spi_set_drvdata(spi, data: chip); |
196 | |
197 | res = ds1390_get_reg(dev: &spi->dev, DS1390_REG_SECONDS, data: &tmp); |
198 | if (res != 0) { |
199 | dev_err(&spi->dev, "unable to read device\n" ); |
200 | return res; |
201 | } |
202 | |
203 | if (spi->dev.of_node) |
204 | ds1390_trickle_of_init(spi); |
205 | |
206 | chip->rtc = devm_rtc_device_register(dev: &spi->dev, name: "ds1390" , |
207 | ops: &ds1390_rtc_ops, THIS_MODULE); |
208 | if (IS_ERR(ptr: chip->rtc)) { |
209 | dev_err(&spi->dev, "unable to register device\n" ); |
210 | res = PTR_ERR(ptr: chip->rtc); |
211 | } |
212 | |
213 | return res; |
214 | } |
215 | |
216 | static const struct of_device_id ds1390_of_match[] __maybe_unused = { |
217 | { .compatible = "dallas,ds1390" }, |
218 | {} |
219 | }; |
220 | MODULE_DEVICE_TABLE(of, ds1390_of_match); |
221 | |
222 | static const struct spi_device_id ds1390_spi_ids[] = { |
223 | { .name = "ds1390" }, |
224 | {} |
225 | }; |
226 | MODULE_DEVICE_TABLE(spi, ds1390_spi_ids); |
227 | |
228 | static struct spi_driver ds1390_driver = { |
229 | .driver = { |
230 | .name = "rtc-ds1390" , |
231 | .of_match_table = of_match_ptr(ds1390_of_match), |
232 | }, |
233 | .probe = ds1390_probe, |
234 | .id_table = ds1390_spi_ids, |
235 | }; |
236 | |
237 | module_spi_driver(ds1390_driver); |
238 | |
239 | MODULE_DESCRIPTION("Dallas/Maxim DS1390/93/94 SPI RTC driver" ); |
240 | MODULE_AUTHOR("Mark Jackson <mpfj@mimc.co.uk>" ); |
241 | MODULE_LICENSE("GPL" ); |
242 | MODULE_ALIAS("spi:rtc-ds1390" ); |
243 | |