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

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