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15#include <linux/bcd.h>
16#include <linux/kernel.h>
17#include <linux/gfp.h>
18#include <linux/delay.h>
19#include <linux/jiffies.h>
20#include <linux/rtc.h>
21#include <linux/of.h>
22#include <linux/of_device.h>
23#include <linux/platform_device.h>
24#include <linux/io.h>
25#include <linux/module.h>
26
27#define RTC_SIZE 8
28
29#define RTC_CONTROL 0
30#define RTC_CENTURY 0
31#define RTC_SECONDS 1
32#define RTC_MINUTES 2
33#define RTC_HOURS 3
34#define RTC_DAY 4
35#define RTC_DATE 5
36#define RTC_MONTH 6
37#define RTC_YEAR 7
38
39#define RTC_CENTURY_MASK 0x3f
40#define RTC_SECONDS_MASK 0x7f
41#define RTC_DAY_MASK 0x07
42
43
44#define RTC_WRITE 0x80
45#define RTC_READ 0x40
46
47
48#define RTC_STOP 0x80
49
50
51#define RTC_BATT_FLAG 0x80
52
53struct rtc_plat_data {
54 void __iomem *ioaddr_nvram;
55 void __iomem *ioaddr_rtc;
56 unsigned long last_jiffies;
57};
58
59static int ds1742_rtc_set_time(struct device *dev, struct rtc_time *tm)
60{
61 struct rtc_plat_data *pdata = dev_get_drvdata(dev);
62 void __iomem *ioaddr = pdata->ioaddr_rtc;
63 u8 century;
64
65 century = bin2bcd((tm->tm_year + 1900) / 100);
66
67 writeb(RTC_WRITE, ioaddr + RTC_CONTROL);
68
69 writeb(bin2bcd(tm->tm_year % 100), ioaddr + RTC_YEAR);
70 writeb(bin2bcd(tm->tm_mon + 1), ioaddr + RTC_MONTH);
71 writeb(bin2bcd(tm->tm_wday) & RTC_DAY_MASK, ioaddr + RTC_DAY);
72 writeb(bin2bcd(tm->tm_mday), ioaddr + RTC_DATE);
73 writeb(bin2bcd(tm->tm_hour), ioaddr + RTC_HOURS);
74 writeb(bin2bcd(tm->tm_min), ioaddr + RTC_MINUTES);
75 writeb(bin2bcd(tm->tm_sec) & RTC_SECONDS_MASK, ioaddr + RTC_SECONDS);
76
77
78 writeb(RTC_WRITE | (century & RTC_CENTURY_MASK), ioaddr + RTC_CENTURY);
79 writeb(century & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL);
80 return 0;
81}
82
83static int ds1742_rtc_read_time(struct device *dev, struct rtc_time *tm)
84{
85 struct rtc_plat_data *pdata = dev_get_drvdata(dev);
86 void __iomem *ioaddr = pdata->ioaddr_rtc;
87 unsigned int year, month, day, hour, minute, second, week;
88 unsigned int century;
89
90
91 if (pdata->last_jiffies == jiffies)
92 msleep(1);
93 pdata->last_jiffies = jiffies;
94 writeb(RTC_READ, ioaddr + RTC_CONTROL);
95 second = readb(ioaddr + RTC_SECONDS) & RTC_SECONDS_MASK;
96 minute = readb(ioaddr + RTC_MINUTES);
97 hour = readb(ioaddr + RTC_HOURS);
98 day = readb(ioaddr + RTC_DATE);
99 week = readb(ioaddr + RTC_DAY) & RTC_DAY_MASK;
100 month = readb(ioaddr + RTC_MONTH);
101 year = readb(ioaddr + RTC_YEAR);
102 century = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK;
103 writeb(0, ioaddr + RTC_CONTROL);
104 tm->tm_sec = bcd2bin(second);
105 tm->tm_min = bcd2bin(minute);
106 tm->tm_hour = bcd2bin(hour);
107 tm->tm_mday = bcd2bin(day);
108 tm->tm_wday = bcd2bin(week);
109 tm->tm_mon = bcd2bin(month) - 1;
110
111 tm->tm_year = bcd2bin(year) + bcd2bin(century) * 100 - 1900;
112
113 return 0;
114}
115
116static const struct rtc_class_ops ds1742_rtc_ops = {
117 .read_time = ds1742_rtc_read_time,
118 .set_time = ds1742_rtc_set_time,
119};
120
121static int ds1742_nvram_read(void *priv, unsigned int pos, void *val,
122 size_t bytes)
123{
124 struct rtc_plat_data *pdata = priv;
125 void __iomem *ioaddr = pdata->ioaddr_nvram;
126 u8 *buf = val;
127
128 for (; bytes; bytes--)
129 *buf++ = readb(ioaddr + pos++);
130 return 0;
131}
132
133static int ds1742_nvram_write(void *priv, unsigned int pos, void *val,
134 size_t bytes)
135{
136 struct rtc_plat_data *pdata = priv;
137 void __iomem *ioaddr = pdata->ioaddr_nvram;
138 u8 *buf = val;
139
140 for (; bytes; bytes--)
141 writeb(*buf++, ioaddr + pos++);
142 return 0;
143}
144
145static int ds1742_rtc_probe(struct platform_device *pdev)
146{
147 struct rtc_device *rtc;
148 struct resource *res;
149 unsigned int cen, sec;
150 struct rtc_plat_data *pdata;
151 void __iomem *ioaddr;
152 int ret = 0;
153 struct nvmem_config nvmem_cfg = {
154 .name = "ds1742_nvram",
155 .reg_read = ds1742_nvram_read,
156 .reg_write = ds1742_nvram_write,
157 };
158
159
160 pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
161 if (!pdata)
162 return -ENOMEM;
163
164 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
165 ioaddr = devm_ioremap_resource(&pdev->dev, res);
166 if (IS_ERR(ioaddr))
167 return PTR_ERR(ioaddr);
168
169 pdata->ioaddr_nvram = ioaddr;
170 pdata->ioaddr_rtc = ioaddr + resource_size(res) - RTC_SIZE;
171
172 nvmem_cfg.size = resource_size(res) - RTC_SIZE;
173 nvmem_cfg.priv = pdata;
174
175
176 ioaddr = pdata->ioaddr_rtc;
177 sec = readb(ioaddr + RTC_SECONDS);
178 if (sec & RTC_STOP) {
179 sec &= RTC_SECONDS_MASK;
180 cen = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK;
181 writeb(RTC_WRITE, ioaddr + RTC_CONTROL);
182 writeb(sec, ioaddr + RTC_SECONDS);
183 writeb(cen & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL);
184 }
185 if (!(readb(ioaddr + RTC_DAY) & RTC_BATT_FLAG))
186 dev_warn(&pdev->dev, "voltage-low detected.\n");
187
188 pdata->last_jiffies = jiffies;
189 platform_set_drvdata(pdev, pdata);
190
191 rtc = devm_rtc_allocate_device(&pdev->dev);
192 if (IS_ERR(rtc))
193 return PTR_ERR(rtc);
194
195 rtc->ops = &ds1742_rtc_ops;
196 rtc->nvram_old_abi = true;
197
198 ret = rtc_register_device(rtc);
199 if (ret)
200 return ret;
201
202 if (rtc_nvmem_register(rtc, &nvmem_cfg))
203 dev_err(&pdev->dev, "Unable to register nvmem\n");
204
205 return 0;
206}
207
208static const struct of_device_id __maybe_unused ds1742_rtc_of_match[] = {
209 { .compatible = "maxim,ds1742", },
210 { }
211};
212MODULE_DEVICE_TABLE(of, ds1742_rtc_of_match);
213
214static struct platform_driver ds1742_rtc_driver = {
215 .probe = ds1742_rtc_probe,
216 .driver = {
217 .name = "rtc-ds1742",
218 .of_match_table = of_match_ptr(ds1742_rtc_of_match),
219 },
220};
221
222module_platform_driver(ds1742_rtc_driver);
223
224MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>");
225MODULE_DESCRIPTION("Dallas DS1742 RTC driver");
226MODULE_LICENSE("GPL");
227MODULE_ALIAS("platform:rtc-ds1742");
228
