GNU Linux-libre 4.4.289-gnu1
[releases.git] / drivers / rtc / rtc-m48t35.c
1 /*
2  * Driver for the SGS-Thomson M48T35 Timekeeper RAM chip
3  *
4  * Copyright (C) 2000 Silicon Graphics, Inc.
5  * Written by Ulf Carlsson (ulfc@engr.sgi.com)
6  *
7  * Copyright (C) 2008 Thomas Bogendoerfer
8  *
9  * Based on code written by Paul Gortmaker.
10  *
11  * This program is free software; you can redistribute it and/or modify it
12  * under the terms of the GNU General Public License as published by the
13  * Free Software Foundation; either version 2 of the License, or (at your
14  * option) any later version.
15  */
16
17 #include <linux/module.h>
18 #include <linux/rtc.h>
19 #include <linux/slab.h>
20 #include <linux/platform_device.h>
21 #include <linux/bcd.h>
22 #include <linux/io.h>
23 #include <linux/err.h>
24
25 #define DRV_VERSION             "1.0"
26
27 struct m48t35_rtc {
28         u8      pad[0x7ff8];    /* starts at 0x7ff8 */
29         u8      control;
30         u8      sec;
31         u8      min;
32         u8      hour;
33         u8      day;
34         u8      date;
35         u8      month;
36         u8      year;
37 };
38
39 #define M48T35_RTC_SET          0x80
40 #define M48T35_RTC_READ         0x40
41
42 struct m48t35_priv {
43         struct rtc_device *rtc;
44         struct m48t35_rtc __iomem *reg;
45         size_t size;
46         unsigned long baseaddr;
47         spinlock_t lock;
48 };
49
50 static int m48t35_read_time(struct device *dev, struct rtc_time *tm)
51 {
52         struct m48t35_priv *priv = dev_get_drvdata(dev);
53         u8 control;
54
55         /*
56          * Only the values that we read from the RTC are set. We leave
57          * tm_wday, tm_yday and tm_isdst untouched. Even though the
58          * RTC has RTC_DAY_OF_WEEK, we ignore it, as it is only updated
59          * by the RTC when initially set to a non-zero value.
60          */
61         spin_lock_irq(&priv->lock);
62         control = readb(&priv->reg->control);
63         writeb(control | M48T35_RTC_READ, &priv->reg->control);
64         tm->tm_sec = readb(&priv->reg->sec);
65         tm->tm_min = readb(&priv->reg->min);
66         tm->tm_hour = readb(&priv->reg->hour);
67         tm->tm_mday = readb(&priv->reg->date);
68         tm->tm_mon = readb(&priv->reg->month);
69         tm->tm_year = readb(&priv->reg->year);
70         writeb(control, &priv->reg->control);
71         spin_unlock_irq(&priv->lock);
72
73         tm->tm_sec = bcd2bin(tm->tm_sec);
74         tm->tm_min = bcd2bin(tm->tm_min);
75         tm->tm_hour = bcd2bin(tm->tm_hour);
76         tm->tm_mday = bcd2bin(tm->tm_mday);
77         tm->tm_mon = bcd2bin(tm->tm_mon);
78         tm->tm_year = bcd2bin(tm->tm_year);
79
80         /*
81          * Account for differences between how the RTC uses the values
82          * and how they are defined in a struct rtc_time;
83          */
84         tm->tm_year += 70;
85         if (tm->tm_year <= 69)
86                 tm->tm_year += 100;
87
88         tm->tm_mon--;
89         return rtc_valid_tm(tm);
90 }
91
92 static int m48t35_set_time(struct device *dev, struct rtc_time *tm)
93 {
94         struct m48t35_priv *priv = dev_get_drvdata(dev);
95         unsigned char mon, day, hrs, min, sec;
96         unsigned int yrs;
97         u8 control;
98
99         yrs = tm->tm_year + 1900;
100         mon = tm->tm_mon + 1;   /* tm_mon starts at zero */
101         day = tm->tm_mday;
102         hrs = tm->tm_hour;
103         min = tm->tm_min;
104         sec = tm->tm_sec;
105
106         if (yrs < 1970)
107                 return -EINVAL;
108
109         yrs -= 1970;
110         if (yrs > 255)    /* They are unsigned */
111                 return -EINVAL;
112
113         if (yrs > 169)
114                 return -EINVAL;
115
116         if (yrs >= 100)
117                 yrs -= 100;
118
119         sec = bin2bcd(sec);
120         min = bin2bcd(min);
121         hrs = bin2bcd(hrs);
122         day = bin2bcd(day);
123         mon = bin2bcd(mon);
124         yrs = bin2bcd(yrs);
125
126         spin_lock_irq(&priv->lock);
127         control = readb(&priv->reg->control);
128         writeb(control | M48T35_RTC_SET, &priv->reg->control);
129         writeb(yrs, &priv->reg->year);
130         writeb(mon, &priv->reg->month);
131         writeb(day, &priv->reg->date);
132         writeb(hrs, &priv->reg->hour);
133         writeb(min, &priv->reg->min);
134         writeb(sec, &priv->reg->sec);
135         writeb(control, &priv->reg->control);
136         spin_unlock_irq(&priv->lock);
137         return 0;
138 }
139
140 static const struct rtc_class_ops m48t35_ops = {
141         .read_time      = m48t35_read_time,
142         .set_time       = m48t35_set_time,
143 };
144
145 static int m48t35_probe(struct platform_device *pdev)
146 {
147         struct resource *res;
148         struct m48t35_priv *priv;
149
150         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
151         if (!res)
152                 return -ENODEV;
153         priv = devm_kzalloc(&pdev->dev, sizeof(struct m48t35_priv), GFP_KERNEL);
154         if (!priv)
155                 return -ENOMEM;
156
157         priv->size = resource_size(res);
158         /*
159          * kludge: remove the #ifndef after ioc3 resource
160          * conflicts are resolved
161          */
162 #ifndef CONFIG_SGI_IP27
163         if (!devm_request_mem_region(&pdev->dev, res->start, priv->size,
164                                      pdev->name))
165                 return -EBUSY;
166 #endif
167         priv->baseaddr = res->start;
168         priv->reg = devm_ioremap(&pdev->dev, priv->baseaddr, priv->size);
169         if (!priv->reg)
170                 return -ENOMEM;
171
172         spin_lock_init(&priv->lock);
173
174         platform_set_drvdata(pdev, priv);
175
176         priv->rtc = devm_rtc_device_register(&pdev->dev, "m48t35",
177                                   &m48t35_ops, THIS_MODULE);
178         return PTR_ERR_OR_ZERO(priv->rtc);
179 }
180
181 static struct platform_driver m48t35_platform_driver = {
182         .driver         = {
183                 .name   = "rtc-m48t35",
184         },
185         .probe          = m48t35_probe,
186 };
187
188 module_platform_driver(m48t35_platform_driver);
189
190 MODULE_AUTHOR("Thomas Bogendoerfer <tsbogend@alpha.franken.de>");
191 MODULE_DESCRIPTION("M48T35 RTC driver");
192 MODULE_LICENSE("GPL");
193 MODULE_VERSION(DRV_VERSION);
194 MODULE_ALIAS("platform:rtc-m48t35");