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
16struct 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
30struct ds1216_priv {
31	struct rtc_device *rtc;
32	void __iomem *ioaddr;
33};
34
35static 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 */
44static 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
57static 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
71static 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
79static 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
107static 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
136static const struct rtc_class_ops ds1216_rtc_ops = {
137	.read_time	= ds1216_rtc_read_time,
138	.set_time	= ds1216_rtc_set_time,
139};
140
141static 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
170static struct platform_driver ds1216_rtc_platform_driver = {
171	.driver		= {
172		.name	= "rtc-ds1216",
173		.owner	= THIS_MODULE,
174	},
175};
176
177module_platform_driver_probe(ds1216_rtc_platform_driver, ds1216_rtc_probe);
178
179MODULE_AUTHOR("Thomas Bogendoerfer <tsbogend@alpha.franken.de>");
180MODULE_DESCRIPTION("DS1216 RTC driver");
181MODULE_LICENSE("GPL");
182MODULE_VERSION(DRV_VERSION);
183MODULE_ALIAS("platform:rtc-ds1216");
184