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Linux/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                 .owner  = THIS_MODULE,
185         },
186         .probe          = m48t35_probe,
187 };
188 
189 module_platform_driver(m48t35_platform_driver);
190 
191 MODULE_AUTHOR("Thomas Bogendoerfer <tsbogend@alpha.franken.de>");
192 MODULE_DESCRIPTION("M48T35 RTC driver");
193 MODULE_LICENSE("GPL");
194 MODULE_VERSION(DRV_VERSION);
195 MODULE_ALIAS("platform:rtc-m48t35");
196 

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