1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* |
3 | * An rtc driver for the Dallas DS1742 |
4 | * |
5 | * Copyright (C) 2006 Atsushi Nemoto <anemo@mba.ocn.ne.jp> |
6 | * |
7 | * Copyright (C) 2006 Torsten Ertbjerg Rasmussen <tr@newtec.dk> |
8 | * - nvram size determined from resource |
9 | * - this ds1742 driver now supports ds1743. |
10 | */ |
11 | |
12 | #include <linux/bcd.h> |
13 | #include <linux/kernel.h> |
14 | #include <linux/gfp.h> |
15 | #include <linux/delay.h> |
16 | #include <linux/jiffies.h> |
17 | #include <linux/rtc.h> |
18 | #include <linux/of.h> |
19 | #include <linux/platform_device.h> |
20 | #include <linux/io.h> |
21 | #include <linux/module.h> |
22 | |
23 | #define RTC_SIZE 8 |
24 | |
25 | #define RTC_CONTROL 0 |
26 | #define RTC_CENTURY 0 |
27 | #define RTC_SECONDS 1 |
28 | #define RTC_MINUTES 2 |
29 | #define RTC_HOURS 3 |
30 | #define RTC_DAY 4 |
31 | #define RTC_DATE 5 |
32 | #define RTC_MONTH 6 |
33 | #define RTC_YEAR 7 |
34 | |
35 | #define RTC_CENTURY_MASK 0x3f |
36 | #define RTC_SECONDS_MASK 0x7f |
37 | #define RTC_DAY_MASK 0x07 |
38 | |
39 | /* Bits in the Control/Century register */ |
40 | #define RTC_WRITE 0x80 |
41 | #define RTC_READ 0x40 |
42 | |
43 | /* Bits in the Seconds register */ |
44 | #define RTC_STOP 0x80 |
45 | |
46 | /* Bits in the Day register */ |
47 | #define RTC_BATT_FLAG 0x80 |
48 | |
49 | struct rtc_plat_data { |
50 | void __iomem *ioaddr_nvram; |
51 | void __iomem *ioaddr_rtc; |
52 | unsigned long last_jiffies; |
53 | }; |
54 | |
55 | static int ds1742_rtc_set_time(struct device *dev, struct rtc_time *tm) |
56 | { |
57 | struct rtc_plat_data *pdata = dev_get_drvdata(dev); |
58 | void __iomem *ioaddr = pdata->ioaddr_rtc; |
59 | u8 century; |
60 | |
61 | century = bin2bcd((tm->tm_year + 1900) / 100); |
62 | |
63 | writeb(RTC_WRITE, addr: ioaddr + RTC_CONTROL); |
64 | |
65 | writeb(bin2bcd(tm->tm_year % 100), addr: ioaddr + RTC_YEAR); |
66 | writeb(bin2bcd(tm->tm_mon + 1), addr: ioaddr + RTC_MONTH); |
67 | writeb(bin2bcd(tm->tm_wday) & RTC_DAY_MASK, addr: ioaddr + RTC_DAY); |
68 | writeb(bin2bcd(tm->tm_mday), addr: ioaddr + RTC_DATE); |
69 | writeb(bin2bcd(tm->tm_hour), addr: ioaddr + RTC_HOURS); |
70 | writeb(bin2bcd(tm->tm_min), addr: ioaddr + RTC_MINUTES); |
71 | writeb(bin2bcd(tm->tm_sec) & RTC_SECONDS_MASK, addr: ioaddr + RTC_SECONDS); |
72 | |
73 | /* RTC_CENTURY and RTC_CONTROL share same register */ |
74 | writeb(RTC_WRITE | (century & RTC_CENTURY_MASK), addr: ioaddr + RTC_CENTURY); |
75 | writeb(val: century & RTC_CENTURY_MASK, addr: ioaddr + RTC_CONTROL); |
76 | return 0; |
77 | } |
78 | |
79 | static int ds1742_rtc_read_time(struct device *dev, struct rtc_time *tm) |
80 | { |
81 | struct rtc_plat_data *pdata = dev_get_drvdata(dev); |
82 | void __iomem *ioaddr = pdata->ioaddr_rtc; |
83 | unsigned int year, month, day, hour, minute, second, week; |
84 | unsigned int century; |
85 | |
86 | /* give enough time to update RTC in case of continuous read */ |
87 | if (pdata->last_jiffies == jiffies) |
88 | msleep(msecs: 1); |
89 | pdata->last_jiffies = jiffies; |
90 | writeb(RTC_READ, addr: ioaddr + RTC_CONTROL); |
91 | second = readb(addr: ioaddr + RTC_SECONDS) & RTC_SECONDS_MASK; |
92 | minute = readb(addr: ioaddr + RTC_MINUTES); |
93 | hour = readb(addr: ioaddr + RTC_HOURS); |
94 | day = readb(addr: ioaddr + RTC_DATE); |
95 | week = readb(addr: ioaddr + RTC_DAY) & RTC_DAY_MASK; |
96 | month = readb(addr: ioaddr + RTC_MONTH); |
97 | year = readb(addr: ioaddr + RTC_YEAR); |
98 | century = readb(addr: ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK; |
99 | writeb(val: 0, addr: ioaddr + RTC_CONTROL); |
100 | tm->tm_sec = bcd2bin(second); |
101 | tm->tm_min = bcd2bin(minute); |
102 | tm->tm_hour = bcd2bin(hour); |
103 | tm->tm_mday = bcd2bin(day); |
104 | tm->tm_wday = bcd2bin(week); |
105 | tm->tm_mon = bcd2bin(month) - 1; |
106 | /* year is 1900 + tm->tm_year */ |
107 | tm->tm_year = bcd2bin(year) + bcd2bin(century) * 100 - 1900; |
108 | |
109 | return 0; |
110 | } |
111 | |
112 | static const struct rtc_class_ops ds1742_rtc_ops = { |
113 | .read_time = ds1742_rtc_read_time, |
114 | .set_time = ds1742_rtc_set_time, |
115 | }; |
116 | |
117 | static int ds1742_nvram_read(void *priv, unsigned int pos, void *val, |
118 | size_t bytes) |
119 | { |
120 | struct rtc_plat_data *pdata = priv; |
121 | void __iomem *ioaddr = pdata->ioaddr_nvram; |
122 | u8 *buf = val; |
123 | |
124 | for (; bytes; bytes--) |
125 | *buf++ = readb(addr: ioaddr + pos++); |
126 | return 0; |
127 | } |
128 | |
129 | static int ds1742_nvram_write(void *priv, unsigned int pos, void *val, |
130 | size_t bytes) |
131 | { |
132 | struct rtc_plat_data *pdata = priv; |
133 | void __iomem *ioaddr = pdata->ioaddr_nvram; |
134 | u8 *buf = val; |
135 | |
136 | for (; bytes; bytes--) |
137 | writeb(val: *buf++, addr: ioaddr + pos++); |
138 | return 0; |
139 | } |
140 | |
141 | static int ds1742_rtc_probe(struct platform_device *pdev) |
142 | { |
143 | struct rtc_device *rtc; |
144 | struct resource *res; |
145 | unsigned int cen, sec; |
146 | struct rtc_plat_data *pdata; |
147 | void __iomem *ioaddr; |
148 | int ret = 0; |
149 | struct nvmem_config nvmem_cfg = { |
150 | .name = "ds1742_nvram" , |
151 | .reg_read = ds1742_nvram_read, |
152 | .reg_write = ds1742_nvram_write, |
153 | }; |
154 | |
155 | |
156 | pdata = devm_kzalloc(dev: &pdev->dev, size: sizeof(*pdata), GFP_KERNEL); |
157 | if (!pdata) |
158 | return -ENOMEM; |
159 | |
160 | ioaddr = devm_platform_get_and_ioremap_resource(pdev, index: 0, res: &res); |
161 | if (IS_ERR(ptr: ioaddr)) |
162 | return PTR_ERR(ptr: ioaddr); |
163 | |
164 | pdata->ioaddr_nvram = ioaddr; |
165 | pdata->ioaddr_rtc = ioaddr + resource_size(res) - RTC_SIZE; |
166 | |
167 | nvmem_cfg.size = resource_size(res) - RTC_SIZE; |
168 | nvmem_cfg.priv = pdata; |
169 | |
170 | /* turn RTC on if it was not on */ |
171 | ioaddr = pdata->ioaddr_rtc; |
172 | sec = readb(addr: ioaddr + RTC_SECONDS); |
173 | if (sec & RTC_STOP) { |
174 | sec &= RTC_SECONDS_MASK; |
175 | cen = readb(addr: ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK; |
176 | writeb(RTC_WRITE, addr: ioaddr + RTC_CONTROL); |
177 | writeb(val: sec, addr: ioaddr + RTC_SECONDS); |
178 | writeb(val: cen & RTC_CENTURY_MASK, addr: ioaddr + RTC_CONTROL); |
179 | } |
180 | if (!(readb(addr: ioaddr + RTC_DAY) & RTC_BATT_FLAG)) |
181 | dev_warn(&pdev->dev, "voltage-low detected.\n" ); |
182 | |
183 | pdata->last_jiffies = jiffies; |
184 | platform_set_drvdata(pdev, data: pdata); |
185 | |
186 | rtc = devm_rtc_allocate_device(dev: &pdev->dev); |
187 | if (IS_ERR(ptr: rtc)) |
188 | return PTR_ERR(ptr: rtc); |
189 | |
190 | rtc->ops = &ds1742_rtc_ops; |
191 | |
192 | ret = devm_rtc_register_device(rtc); |
193 | if (ret) |
194 | return ret; |
195 | |
196 | devm_rtc_nvmem_register(rtc, nvmem_config: &nvmem_cfg); |
197 | |
198 | return 0; |
199 | } |
200 | |
201 | static const struct of_device_id __maybe_unused ds1742_rtc_of_match[] = { |
202 | { .compatible = "maxim,ds1742" , }, |
203 | { } |
204 | }; |
205 | MODULE_DEVICE_TABLE(of, ds1742_rtc_of_match); |
206 | |
207 | static struct platform_driver ds1742_rtc_driver = { |
208 | .probe = ds1742_rtc_probe, |
209 | .driver = { |
210 | .name = "rtc-ds1742" , |
211 | .of_match_table = of_match_ptr(ds1742_rtc_of_match), |
212 | }, |
213 | }; |
214 | |
215 | module_platform_driver(ds1742_rtc_driver); |
216 | |
217 | MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>" ); |
218 | MODULE_DESCRIPTION("Dallas DS1742 RTC driver" ); |
219 | MODULE_LICENSE("GPL" ); |
220 | MODULE_ALIAS("platform:rtc-ds1742" ); |
221 | |