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Linux/drivers/rtc/rtc-ds1216.c

  1 /*
  2  * Dallas DS1216 RTC driver
  3  *
  4  * Copyright (c) 2007 Thomas Bogendoerfer
  5  *
  6  */
  7 
  8 #include <linux/module.h>
  9 #include <linux/rtc.h>
 10 #include <linux/platform_device.h>
 11 #include <linux/bcd.h>
 12 #include <linux/slab.h>
 13 
 14 #define DRV_VERSION "0.2"
 15 
 16 struct ds1216_regs {
 17         u8 tsec;
 18         u8 sec;
 19         u8 min;
 20         u8 hour;
 21         u8 wday;
 22         u8 mday;
 23         u8 month;
 24         u8 year;
 25 };
 26 
 27 #define DS1216_HOUR_1224        (1 << 7)
 28 #define DS1216_HOUR_AMPM        (1 << 5)
 29 
 30 struct ds1216_priv {
 31         struct rtc_device *rtc;
 32         void __iomem *ioaddr;
 33 };
 34 
 35 static const u8 magic[] = {
 36         0xc5, 0x3a, 0xa3, 0x5c, 0xc5, 0x3a, 0xa3, 0x5c
 37 };
 38 
 39 /*
 40  * Read the 64 bit we'd like to have - It a series
 41  * of 64 bits showing up in the LSB of the base register.
 42  *
 43  */
 44 static void ds1216_read(u8 __iomem *ioaddr, u8 *buf)
 45 {
 46         unsigned char c;
 47         int i, j;
 48 
 49         for (i = 0; i < 8; i++) {
 50                 c = 0;
 51                 for (j = 0; j < 8; j++)
 52                         c |= (readb(ioaddr) & 0x1) << j;
 53                 buf[i] = c;
 54         }
 55 }
 56 
 57 static void ds1216_write(u8 __iomem *ioaddr, const u8 *buf)
 58 {
 59         unsigned char c;
 60         int i, j;
 61 
 62         for (i = 0; i < 8; i++) {
 63                 c = buf[i];
 64                 for (j = 0; j < 8; j++) {
 65                         writeb(c, ioaddr);
 66                         c = c >> 1;
 67                 }
 68         }
 69 }
 70 
 71 static void ds1216_switch_ds_to_clock(u8 __iomem *ioaddr)
 72 {
 73         /* Reset magic pointer */
 74         readb(ioaddr);
 75         /* Write 64 bit magic to DS1216 */
 76         ds1216_write(ioaddr, magic);
 77 }
 78 
 79 static int ds1216_rtc_read_time(struct device *dev, struct rtc_time *tm)
 80 {
 81         struct platform_device *pdev = to_platform_device(dev);
 82         struct ds1216_priv *priv = platform_get_drvdata(pdev);
 83         struct ds1216_regs regs;
 84 
 85         ds1216_switch_ds_to_clock(priv->ioaddr);
 86         ds1216_read(priv->ioaddr, (u8 *)&regs);
 87 
 88         tm->tm_sec = bcd2bin(regs.sec);
 89         tm->tm_min = bcd2bin(regs.min);
 90         if (regs.hour & DS1216_HOUR_1224) {
 91                 /* AM/PM mode */
 92                 tm->tm_hour = bcd2bin(regs.hour & 0x1f);
 93                 if (regs.hour & DS1216_HOUR_AMPM)
 94                         tm->tm_hour += 12;
 95         } else
 96                 tm->tm_hour = bcd2bin(regs.hour & 0x3f);
 97         tm->tm_wday = (regs.wday & 7) - 1;
 98         tm->tm_mday = bcd2bin(regs.mday & 0x3f);
 99         tm->tm_mon = bcd2bin(regs.month & 0x1f);
100         tm->tm_year = bcd2bin(regs.year);
101         if (tm->tm_year < 70)
102                 tm->tm_year += 100;
103 
104         return rtc_valid_tm(tm);
105 }
106 
107 static int ds1216_rtc_set_time(struct device *dev, struct rtc_time *tm)
108 {
109         struct platform_device *pdev = to_platform_device(dev);
110         struct ds1216_priv *priv = platform_get_drvdata(pdev);
111         struct ds1216_regs regs;
112 
113         ds1216_switch_ds_to_clock(priv->ioaddr);
114         ds1216_read(priv->ioaddr, (u8 *)&regs);
115 
116         regs.tsec = 0; /* clear 0.1 and 0.01 seconds */
117         regs.sec = bin2bcd(tm->tm_sec);
118         regs.min = bin2bcd(tm->tm_min);
119         regs.hour &= DS1216_HOUR_1224;
120         if (regs.hour && tm->tm_hour > 12) {
121                 regs.hour |= DS1216_HOUR_AMPM;
122                 tm->tm_hour -= 12;
123         }
124         regs.hour |= bin2bcd(tm->tm_hour);
125         regs.wday &= ~7;
126         regs.wday |= tm->tm_wday;
127         regs.mday = bin2bcd(tm->tm_mday);
128         regs.month = bin2bcd(tm->tm_mon);
129         regs.year = bin2bcd(tm->tm_year % 100);
130 
131         ds1216_switch_ds_to_clock(priv->ioaddr);
132         ds1216_write(priv->ioaddr, (u8 *)&regs);
133         return 0;
134 }
135 
136 static const struct rtc_class_ops ds1216_rtc_ops = {
137         .read_time      = ds1216_rtc_read_time,
138         .set_time       = ds1216_rtc_set_time,
139 };
140 
141 static int __init ds1216_rtc_probe(struct platform_device *pdev)
142 {
143         struct resource *res;
144         struct ds1216_priv *priv;
145         u8 dummy[8];
146 
147         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
148         if (!res)
149                 return -ENODEV;
150         priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
151         if (!priv)
152                 return -ENOMEM;
153 
154         platform_set_drvdata(pdev, priv);
155 
156         priv->ioaddr = devm_ioremap_resource(&pdev->dev, res);
157         if (IS_ERR(priv->ioaddr))
158                 return PTR_ERR(priv->ioaddr);
159 
160         priv->rtc = devm_rtc_device_register(&pdev->dev, "ds1216",
161                                         &ds1216_rtc_ops, THIS_MODULE);
162         if (IS_ERR(priv->rtc))
163                 return PTR_ERR(priv->rtc);
164 
165         /* dummy read to get clock into a known state */
166         ds1216_read(priv->ioaddr, dummy);
167         return 0;
168 }
169 
170 static struct platform_driver ds1216_rtc_platform_driver = {
171         .driver         = {
172                 .name   = "rtc-ds1216",
173                 .owner  = THIS_MODULE,
174         },
175 };
176 
177 module_platform_driver_probe(ds1216_rtc_platform_driver, ds1216_rtc_probe);
178 
179 MODULE_AUTHOR("Thomas Bogendoerfer <tsbogend@alpha.franken.de>");
180 MODULE_DESCRIPTION("DS1216 RTC driver");
181 MODULE_LICENSE("GPL");
182 MODULE_VERSION(DRV_VERSION);
183 MODULE_ALIAS("platform:rtc-ds1216");
184 

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