tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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
14struct 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
28struct ds1216_priv {
29 struct rtc_device *rtc;
30 void __iomem *ioaddr;
31};
32
33static 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 */
42static 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
55static 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
69static 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
77static int ds1216_rtc_read_time(struct device *dev, struct rtc_time *tm)
78{
79 struct ds1216_priv *priv = dev_get_drvdata(dev);
80 struct ds1216_regs regs;
81
82 ds1216_switch_ds_to_clock(priv->ioaddr);
83 ds1216_read(priv->ioaddr, (u8 *)®s);
84
85 tm->tm_sec = bcd2bin(regs.sec);
86 tm->tm_min = bcd2bin(regs.min);
87 if (regs.hour & DS1216_HOUR_1224) {
88 /* AM/PM mode */
89 tm->tm_hour = bcd2bin(regs.hour & 0x1f);
90 if (regs.hour & DS1216_HOUR_AMPM)
91 tm->tm_hour += 12;
92 } else
93 tm->tm_hour = bcd2bin(regs.hour & 0x3f);
94 tm->tm_wday = (regs.wday & 7) - 1;
95 tm->tm_mday = bcd2bin(regs.mday & 0x3f);
96 tm->tm_mon = bcd2bin(regs.month & 0x1f);
97 tm->tm_year = bcd2bin(regs.year);
98 if (tm->tm_year < 70)
99 tm->tm_year += 100;
100
101 return 0;
102}
103
104static int ds1216_rtc_set_time(struct device *dev, struct rtc_time *tm)
105{
106 struct ds1216_priv *priv = dev_get_drvdata(dev);
107 struct ds1216_regs regs;
108
109 ds1216_switch_ds_to_clock(priv->ioaddr);
110 ds1216_read(priv->ioaddr, (u8 *)®s);
111
112 regs.tsec = 0; /* clear 0.1 and 0.01 seconds */
113 regs.sec = bin2bcd(tm->tm_sec);
114 regs.min = bin2bcd(tm->tm_min);
115 regs.hour &= DS1216_HOUR_1224;
116 if (regs.hour && tm->tm_hour > 12) {
117 regs.hour |= DS1216_HOUR_AMPM;
118 tm->tm_hour -= 12;
119 }
120 regs.hour |= bin2bcd(tm->tm_hour);
121 regs.wday &= ~7;
122 regs.wday |= tm->tm_wday;
123 regs.mday = bin2bcd(tm->tm_mday);
124 regs.month = bin2bcd(tm->tm_mon);
125 regs.year = bin2bcd(tm->tm_year % 100);
126
127 ds1216_switch_ds_to_clock(priv->ioaddr);
128 ds1216_write(priv->ioaddr, (u8 *)®s);
129 return 0;
130}
131
132static const struct rtc_class_ops ds1216_rtc_ops = {
133 .read_time = ds1216_rtc_read_time,
134 .set_time = ds1216_rtc_set_time,
135};
136
137static int __init ds1216_rtc_probe(struct platform_device *pdev)
138{
139 struct resource *res;
140 struct ds1216_priv *priv;
141 u8 dummy[8];
142
143 priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
144 if (!priv)
145 return -ENOMEM;
146
147 platform_set_drvdata(pdev, priv);
148
149 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
150 priv->ioaddr = devm_ioremap_resource(&pdev->dev, res);
151 if (IS_ERR(priv->ioaddr))
152 return PTR_ERR(priv->ioaddr);
153
154 priv->rtc = devm_rtc_device_register(&pdev->dev, "ds1216",
155 &ds1216_rtc_ops, THIS_MODULE);
156 if (IS_ERR(priv->rtc))
157 return PTR_ERR(priv->rtc);
158
159 /* dummy read to get clock into a known state */
160 ds1216_read(priv->ioaddr, dummy);
161 return 0;
162}
163
164static struct platform_driver ds1216_rtc_platform_driver = {
165 .driver = {
166 .name = "rtc-ds1216",
167 },
168};
169
170module_platform_driver_probe(ds1216_rtc_platform_driver, ds1216_rtc_probe);
171
172MODULE_AUTHOR("Thomas Bogendoerfer <tsbogend@alpha.franken.de>");
173MODULE_DESCRIPTION("DS1216 RTC driver");
174MODULE_LICENSE("GPL");
175MODULE_ALIAS("platform:rtc-ds1216");