UPSTREAM Revert 3.9 "rtc: palmas: Add RTC driver Palmas series PMIC"
[linux-3.10.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
24 #define DRV_VERSION             "1.0"
25
26 struct m48t35_rtc {
27         u8      pad[0x7ff8];    /* starts at 0x7ff8 */
28         u8      control;
29         u8      sec;
30         u8      min;
31         u8      hour;
32         u8      day;
33         u8      date;
34         u8      month;
35         u8      year;
36 };
37
38 #define M48T35_RTC_SET          0x80
39 #define M48T35_RTC_READ         0x40
40
41 struct m48t35_priv {
42         struct rtc_device *rtc;
43         struct m48t35_rtc __iomem *reg;
44         size_t size;
45         unsigned long baseaddr;
46         spinlock_t lock;
47 };
48
49 static int m48t35_read_time(struct device *dev, struct rtc_time *tm)
50 {
51         struct m48t35_priv *priv = dev_get_drvdata(dev);
52         u8 control;
53
54         /*
55          * Only the values that we read from the RTC are set. We leave
56          * tm_wday, tm_yday and tm_isdst untouched. Even though the
57          * RTC has RTC_DAY_OF_WEEK, we ignore it, as it is only updated
58          * by the RTC when initially set to a non-zero value.
59          */
60         spin_lock_irq(&priv->lock);
61         control = readb(&priv->reg->control);
62         writeb(control | M48T35_RTC_READ, &priv->reg->control);
63         tm->tm_sec = readb(&priv->reg->sec);
64         tm->tm_min = readb(&priv->reg->min);
65         tm->tm_hour = readb(&priv->reg->hour);
66         tm->tm_mday = readb(&priv->reg->date);
67         tm->tm_mon = readb(&priv->reg->month);
68         tm->tm_year = readb(&priv->reg->year);
69         writeb(control, &priv->reg->control);
70         spin_unlock_irq(&priv->lock);
71
72         tm->tm_sec = bcd2bin(tm->tm_sec);
73         tm->tm_min = bcd2bin(tm->tm_min);
74         tm->tm_hour = bcd2bin(tm->tm_hour);
75         tm->tm_mday = bcd2bin(tm->tm_mday);
76         tm->tm_mon = bcd2bin(tm->tm_mon);
77         tm->tm_year = bcd2bin(tm->tm_year);
78
79         /*
80          * Account for differences between how the RTC uses the values
81          * and how they are defined in a struct rtc_time;
82          */
83         tm->tm_year += 70;
84         if (tm->tm_year <= 69)
85                 tm->tm_year += 100;
86
87         tm->tm_mon--;
88         return rtc_valid_tm(tm);
89 }
90
91 static int m48t35_set_time(struct device *dev, struct rtc_time *tm)
92 {
93         struct m48t35_priv *priv = dev_get_drvdata(dev);
94         unsigned char mon, day, hrs, min, sec;
95         unsigned int yrs;
96         u8 control;
97
98         yrs = tm->tm_year + 1900;
99         mon = tm->tm_mon + 1;   /* tm_mon starts at zero */
100         day = tm->tm_mday;
101         hrs = tm->tm_hour;
102         min = tm->tm_min;
103         sec = tm->tm_sec;
104
105         if (yrs < 1970)
106                 return -EINVAL;
107
108         yrs -= 1970;
109         if (yrs > 255)    /* They are unsigned */
110                 return -EINVAL;
111
112         if (yrs > 169)
113                 return -EINVAL;
114
115         if (yrs >= 100)
116                 yrs -= 100;
117
118         sec = bin2bcd(sec);
119         min = bin2bcd(min);
120         hrs = bin2bcd(hrs);
121         day = bin2bcd(day);
122         mon = bin2bcd(mon);
123         yrs = bin2bcd(yrs);
124
125         spin_lock_irq(&priv->lock);
126         control = readb(&priv->reg->control);
127         writeb(control | M48T35_RTC_SET, &priv->reg->control);
128         writeb(yrs, &priv->reg->year);
129         writeb(mon, &priv->reg->month);
130         writeb(day, &priv->reg->date);
131         writeb(hrs, &priv->reg->hour);
132         writeb(min, &priv->reg->min);
133         writeb(sec, &priv->reg->sec);
134         writeb(control, &priv->reg->control);
135         spin_unlock_irq(&priv->lock);
136         return 0;
137 }
138
139 static const struct rtc_class_ops m48t35_ops = {
140         .read_time      = m48t35_read_time,
141         .set_time       = m48t35_set_time,
142 };
143
144 static int m48t35_probe(struct platform_device *pdev)
145 {
146         struct resource *res;
147         struct m48t35_priv *priv;
148
149         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
150         if (!res)
151                 return -ENODEV;
152         priv = devm_kzalloc(&pdev->dev, sizeof(struct m48t35_priv), GFP_KERNEL);
153         if (!priv)
154                 return -ENOMEM;
155
156         priv->size = resource_size(res);
157         /*
158          * kludge: remove the #ifndef after ioc3 resource
159          * conflicts are resolved
160          */
161 #ifndef CONFIG_SGI_IP27
162         if (!devm_request_mem_region(&pdev->dev, res->start, priv->size,
163                                      pdev->name))
164                 return -EBUSY;
165 #endif
166         priv->baseaddr = res->start;
167         priv->reg = devm_ioremap(&pdev->dev, priv->baseaddr, priv->size);
168         if (!priv->reg)
169                 return -ENOMEM;
170
171         spin_lock_init(&priv->lock);
172
173         platform_set_drvdata(pdev, priv);
174
175         priv->rtc = devm_rtc_device_register(&pdev->dev, "m48t35",
176                                   &m48t35_ops, THIS_MODULE);
177         if (IS_ERR(priv->rtc))
178                 return PTR_ERR(priv->rtc);
179
180         return 0;
181 }
182
183 static int m48t35_remove(struct platform_device *pdev)
184 {
185         return 0;
186 }
187
188 static struct platform_driver m48t35_platform_driver = {
189         .driver         = {
190                 .name   = "rtc-m48t35",
191                 .owner  = THIS_MODULE,
192         },
193         .probe          = m48t35_probe,
194         .remove         = m48t35_remove,
195 };
196
197 module_platform_driver(m48t35_platform_driver);
198
199 MODULE_AUTHOR("Thomas Bogendoerfer <tsbogend@alpha.franken.de>");
200 MODULE_DESCRIPTION("M48T35 RTC driver");
201 MODULE_LICENSE("GPL");
202 MODULE_VERSION(DRV_VERSION);
203 MODULE_ALIAS("platform:rtc-m48t35");