2 * Dallas DS1216 RTC driver
4 * Copyright (c) 2007 Thomas Bogendoerfer
8 #include <linux/module.h>
10 #include <linux/platform_device.h>
11 #include <linux/bcd.h>
13 #define DRV_VERSION "0.2"
26 #define DS1216_HOUR_1224 (1 << 7)
27 #define DS1216_HOUR_AMPM (1 << 5)
30 struct rtc_device *rtc;
33 unsigned long baseaddr;
36 static const u8 magic[] = {
37 0xc5, 0x3a, 0xa3, 0x5c, 0xc5, 0x3a, 0xa3, 0x5c
41 * Read the 64 bit we'd like to have - It a series
42 * of 64 bits showing up in the LSB of the base register.
45 static void ds1216_read(u8 __iomem *ioaddr, u8 *buf)
50 for (i = 0; i < 8; i++) {
52 for (j = 0; j < 8; j++)
53 c |= (readb(ioaddr) & 0x1) << j;
58 static void ds1216_write(u8 __iomem *ioaddr, const u8 *buf)
63 for (i = 0; i < 8; i++) {
65 for (j = 0; j < 8; j++) {
72 static void ds1216_switch_ds_to_clock(u8 __iomem *ioaddr)
74 /* Reset magic pointer */
76 /* Write 64 bit magic to DS1216 */
77 ds1216_write(ioaddr, magic);
80 static int ds1216_rtc_read_time(struct device *dev, struct rtc_time *tm)
82 struct platform_device *pdev = to_platform_device(dev);
83 struct ds1216_priv *priv = platform_get_drvdata(pdev);
84 struct ds1216_regs regs;
86 ds1216_switch_ds_to_clock(priv->ioaddr);
87 ds1216_read(priv->ioaddr, (u8 *)®s);
89 tm->tm_sec = bcd2bin(regs.sec);
90 tm->tm_min = bcd2bin(regs.min);
91 if (regs.hour & DS1216_HOUR_1224) {
93 tm->tm_hour = bcd2bin(regs.hour & 0x1f);
94 if (regs.hour & DS1216_HOUR_AMPM)
97 tm->tm_hour = bcd2bin(regs.hour & 0x3f);
98 tm->tm_wday = (regs.wday & 7) - 1;
99 tm->tm_mday = bcd2bin(regs.mday & 0x3f);
100 tm->tm_mon = bcd2bin(regs.month & 0x1f);
101 tm->tm_year = bcd2bin(regs.year);
102 if (tm->tm_year < 70)
105 return rtc_valid_tm(tm);
108 static int ds1216_rtc_set_time(struct device *dev, struct rtc_time *tm)
110 struct platform_device *pdev = to_platform_device(dev);
111 struct ds1216_priv *priv = platform_get_drvdata(pdev);
112 struct ds1216_regs regs;
114 ds1216_switch_ds_to_clock(priv->ioaddr);
115 ds1216_read(priv->ioaddr, (u8 *)®s);
117 regs.tsec = 0; /* clear 0.1 and 0.01 seconds */
118 regs.sec = bin2bcd(tm->tm_sec);
119 regs.min = bin2bcd(tm->tm_min);
120 regs.hour &= DS1216_HOUR_1224;
121 if (regs.hour && tm->tm_hour > 12) {
122 regs.hour |= DS1216_HOUR_AMPM;
125 regs.hour |= bin2bcd(tm->tm_hour);
127 regs.wday |= tm->tm_wday;
128 regs.mday = bin2bcd(tm->tm_mday);
129 regs.month = bin2bcd(tm->tm_mon);
130 regs.year = bin2bcd(tm->tm_year % 100);
132 ds1216_switch_ds_to_clock(priv->ioaddr);
133 ds1216_write(priv->ioaddr, (u8 *)®s);
137 static const struct rtc_class_ops ds1216_rtc_ops = {
138 .read_time = ds1216_rtc_read_time,
139 .set_time = ds1216_rtc_set_time,
142 static int __init ds1216_rtc_probe(struct platform_device *pdev)
144 struct resource *res;
145 struct ds1216_priv *priv;
149 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
152 priv = kzalloc(sizeof *priv, GFP_KERNEL);
156 platform_set_drvdata(pdev, priv);
158 priv->size = resource_size(res);
159 if (!request_mem_region(res->start, priv->size, pdev->name)) {
163 priv->baseaddr = res->start;
164 priv->ioaddr = ioremap(priv->baseaddr, priv->size);
169 priv->rtc = rtc_device_register("ds1216", &pdev->dev,
170 &ds1216_rtc_ops, THIS_MODULE);
171 if (IS_ERR(priv->rtc)) {
172 ret = PTR_ERR(priv->rtc);
176 /* dummy read to get clock into a known state */
177 ds1216_read(priv->ioaddr, dummy);
182 iounmap(priv->ioaddr);
184 release_mem_region(priv->baseaddr, priv->size);
189 static int __exit ds1216_rtc_remove(struct platform_device *pdev)
191 struct ds1216_priv *priv = platform_get_drvdata(pdev);
193 rtc_device_unregister(priv->rtc);
194 iounmap(priv->ioaddr);
195 release_mem_region(priv->baseaddr, priv->size);
200 static struct platform_driver ds1216_rtc_platform_driver = {
202 .name = "rtc-ds1216",
203 .owner = THIS_MODULE,
205 .remove = __exit_p(ds1216_rtc_remove),
208 static int __init ds1216_rtc_init(void)
210 return platform_driver_probe(&ds1216_rtc_platform_driver, ds1216_rtc_probe);
213 static void __exit ds1216_rtc_exit(void)
215 platform_driver_unregister(&ds1216_rtc_platform_driver);
218 MODULE_AUTHOR("Thomas Bogendoerfer <tsbogend@alpha.franken.de>");
219 MODULE_DESCRIPTION("DS1216 RTC driver");
220 MODULE_LICENSE("GPL");
221 MODULE_VERSION(DRV_VERSION);
222 MODULE_ALIAS("platform:rtc-ds1216");
224 module_init(ds1216_rtc_init);
225 module_exit(ds1216_rtc_exit);