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

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