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 size_t size;
34 unsigned long baseaddr;
35 };
36
37 static const u8 magic[] = {
38 0xc5, 0x3a, 0xa3, 0x5c, 0xc5, 0x3a, 0xa3, 0x5c
39 };
40
41 /*
42 * Read the 64 bit we'd like to have - It a series
43 * of 64 bits showing up in the LSB of the base register.
44 *
45 */
ds1216_read(u8 __iomem * ioaddr,u8 * buf)46 static void ds1216_read(u8 __iomem *ioaddr, u8 *buf)
47 {
48 unsigned char c;
49 int i, j;
50
51 for (i = 0; i < 8; i++) {
52 c = 0;
53 for (j = 0; j < 8; j++)
54 c |= (readb(ioaddr) & 0x1) << j;
55 buf[i] = c;
56 }
57 }
58
ds1216_write(u8 __iomem * ioaddr,const u8 * buf)59 static void ds1216_write(u8 __iomem *ioaddr, const u8 *buf)
60 {
61 unsigned char c;
62 int i, j;
63
64 for (i = 0; i < 8; i++) {
65 c = buf[i];
66 for (j = 0; j < 8; j++) {
67 writeb(c, ioaddr);
68 c = c >> 1;
69 }
70 }
71 }
72
ds1216_switch_ds_to_clock(u8 __iomem * ioaddr)73 static void ds1216_switch_ds_to_clock(u8 __iomem *ioaddr)
74 {
75 /* Reset magic pointer */
76 readb(ioaddr);
77 /* Write 64 bit magic to DS1216 */
78 ds1216_write(ioaddr, magic);
79 }
80
ds1216_rtc_read_time(struct device * dev,struct rtc_time * tm)81 static int ds1216_rtc_read_time(struct device *dev, struct rtc_time *tm)
82 {
83 struct platform_device *pdev = to_platform_device(dev);
84 struct ds1216_priv *priv = platform_get_drvdata(pdev);
85 struct ds1216_regs regs;
86
87 ds1216_switch_ds_to_clock(priv->ioaddr);
88 ds1216_read(priv->ioaddr, (u8 *)®s);
89
90 tm->tm_sec = bcd2bin(regs.sec);
91 tm->tm_min = bcd2bin(regs.min);
92 if (regs.hour & DS1216_HOUR_1224) {
93 /* AM/PM mode */
94 tm->tm_hour = bcd2bin(regs.hour & 0x1f);
95 if (regs.hour & DS1216_HOUR_AMPM)
96 tm->tm_hour += 12;
97 } else
98 tm->tm_hour = bcd2bin(regs.hour & 0x3f);
99 tm->tm_wday = (regs.wday & 7) - 1;
100 tm->tm_mday = bcd2bin(regs.mday & 0x3f);
101 tm->tm_mon = bcd2bin(regs.month & 0x1f);
102 tm->tm_year = bcd2bin(regs.year);
103 if (tm->tm_year < 70)
104 tm->tm_year += 100;
105
106 return rtc_valid_tm(tm);
107 }
108
ds1216_rtc_set_time(struct device * dev,struct rtc_time * tm)109 static int ds1216_rtc_set_time(struct device *dev, struct rtc_time *tm)
110 {
111 struct platform_device *pdev = to_platform_device(dev);
112 struct ds1216_priv *priv = platform_get_drvdata(pdev);
113 struct ds1216_regs regs;
114
115 ds1216_switch_ds_to_clock(priv->ioaddr);
116 ds1216_read(priv->ioaddr, (u8 *)®s);
117
118 regs.tsec = 0; /* clear 0.1 and 0.01 seconds */
119 regs.sec = bin2bcd(tm->tm_sec);
120 regs.min = bin2bcd(tm->tm_min);
121 regs.hour &= DS1216_HOUR_1224;
122 if (regs.hour && tm->tm_hour > 12) {
123 regs.hour |= DS1216_HOUR_AMPM;
124 tm->tm_hour -= 12;
125 }
126 regs.hour |= bin2bcd(tm->tm_hour);
127 regs.wday &= ~7;
128 regs.wday |= tm->tm_wday;
129 regs.mday = bin2bcd(tm->tm_mday);
130 regs.month = bin2bcd(tm->tm_mon);
131 regs.year = bin2bcd(tm->tm_year % 100);
132
133 ds1216_switch_ds_to_clock(priv->ioaddr);
134 ds1216_write(priv->ioaddr, (u8 *)®s);
135 return 0;
136 }
137
138 static const struct rtc_class_ops ds1216_rtc_ops = {
139 .read_time = ds1216_rtc_read_time,
140 .set_time = ds1216_rtc_set_time,
141 };
142
ds1216_rtc_probe(struct platform_device * pdev)143 static int __init ds1216_rtc_probe(struct platform_device *pdev)
144 {
145 struct resource *res;
146 struct ds1216_priv *priv;
147 int ret = 0;
148 u8 dummy[8];
149
150 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
151 if (!res)
152 return -ENODEV;
153 priv = kzalloc(sizeof *priv, GFP_KERNEL);
154 if (!priv)
155 return -ENOMEM;
156
157 platform_set_drvdata(pdev, priv);
158
159 priv->size = resource_size(res);
160 if (!request_mem_region(res->start, priv->size, pdev->name)) {
161 ret = -EBUSY;
162 goto out;
163 }
164 priv->baseaddr = res->start;
165 priv->ioaddr = ioremap(priv->baseaddr, priv->size);
166 if (!priv->ioaddr) {
167 ret = -ENOMEM;
168 goto out;
169 }
170 priv->rtc = rtc_device_register("ds1216", &pdev->dev,
171 &ds1216_rtc_ops, THIS_MODULE);
172 if (IS_ERR(priv->rtc)) {
173 ret = PTR_ERR(priv->rtc);
174 goto out;
175 }
176
177 /* dummy read to get clock into a known state */
178 ds1216_read(priv->ioaddr, dummy);
179 return 0;
180
181 out:
182 if (priv->ioaddr)
183 iounmap(priv->ioaddr);
184 if (priv->baseaddr)
185 release_mem_region(priv->baseaddr, priv->size);
186 kfree(priv);
187 return ret;
188 }
189
ds1216_rtc_remove(struct platform_device * pdev)190 static int __exit ds1216_rtc_remove(struct platform_device *pdev)
191 {
192 struct ds1216_priv *priv = platform_get_drvdata(pdev);
193
194 rtc_device_unregister(priv->rtc);
195 iounmap(priv->ioaddr);
196 release_mem_region(priv->baseaddr, priv->size);
197 kfree(priv);
198 return 0;
199 }
200
201 static struct platform_driver ds1216_rtc_platform_driver = {
202 .driver = {
203 .name = "rtc-ds1216",
204 .owner = THIS_MODULE,
205 },
206 .remove = __exit_p(ds1216_rtc_remove),
207 };
208
ds1216_rtc_init(void)209 static int __init ds1216_rtc_init(void)
210 {
211 return platform_driver_probe(&ds1216_rtc_platform_driver, ds1216_rtc_probe);
212 }
213
ds1216_rtc_exit(void)214 static void __exit ds1216_rtc_exit(void)
215 {
216 platform_driver_unregister(&ds1216_rtc_platform_driver);
217 }
218
219 MODULE_AUTHOR("Thomas Bogendoerfer <tsbogend@alpha.franken.de>");
220 MODULE_DESCRIPTION("DS1216 RTC driver");
221 MODULE_LICENSE("GPL");
222 MODULE_VERSION(DRV_VERSION);
223 MODULE_ALIAS("platform:rtc-ds1216");
224
225 module_init(ds1216_rtc_init);
226 module_exit(ds1216_rtc_exit);
227