xref: /openbmc/linux/drivers/rtc/rtc-ds1302.c (revision 22246614)
1 /*
2  * Dallas DS1302 RTC Support
3  *
4  *  Copyright (C) 2002  David McCullough
5  *  Copyright (C) 2003 - 2007  Paul Mundt
6  *
7  * This file is subject to the terms and conditions of the GNU General Public
8  * License version 2.  See the file "COPYING" in the main directory of
9  * this archive for more details.
10  */
11 #include <linux/init.h>
12 #include <linux/module.h>
13 #include <linux/kernel.h>
14 #include <linux/platform_device.h>
15 #include <linux/time.h>
16 #include <linux/rtc.h>
17 #include <linux/spinlock.h>
18 #include <linux/io.h>
19 #include <linux/bcd.h>
20 #include <asm/rtc.h>
21 
22 #define DRV_NAME	"rtc-ds1302"
23 #define DRV_VERSION	"0.1.0"
24 
25 #define	RTC_CMD_READ	0x81		/* Read command */
26 #define	RTC_CMD_WRITE	0x80		/* Write command */
27 
28 #define RTC_ADDR_RAM0	0x20		/* Address of RAM0 */
29 #define RTC_ADDR_TCR	0x08		/* Address of trickle charge register */
30 #define	RTC_ADDR_YEAR	0x06		/* Address of year register */
31 #define	RTC_ADDR_DAY	0x05		/* Address of day of week register */
32 #define	RTC_ADDR_MON	0x04		/* Address of month register */
33 #define	RTC_ADDR_DATE	0x03		/* Address of day of month register */
34 #define	RTC_ADDR_HOUR	0x02		/* Address of hour register */
35 #define	RTC_ADDR_MIN	0x01		/* Address of minute register */
36 #define	RTC_ADDR_SEC	0x00		/* Address of second register */
37 
38 #define	RTC_RESET	0x1000
39 #define	RTC_IODATA	0x0800
40 #define	RTC_SCLK	0x0400
41 
42 #ifdef CONFIG_SH_SECUREEDGE5410
43 #include <asm/snapgear.h>
44 #define set_dp(x)	SECUREEDGE_WRITE_IOPORT(x, 0x1c00)
45 #define get_dp()	SECUREEDGE_READ_IOPORT()
46 #else
47 #error "Add support for your platform"
48 #endif
49 
50 struct ds1302_rtc {
51 	struct rtc_device *rtc_dev;
52 	spinlock_t lock;
53 };
54 
55 static void ds1302_sendbits(unsigned int val)
56 {
57 	int i;
58 
59 	for (i = 8; (i); i--, val >>= 1) {
60 		set_dp((get_dp() & ~RTC_IODATA) | ((val & 0x1) ?
61 			RTC_IODATA : 0));
62 		set_dp(get_dp() | RTC_SCLK);	/* clock high */
63 		set_dp(get_dp() & ~RTC_SCLK);	/* clock low */
64 	}
65 }
66 
67 static unsigned int ds1302_recvbits(void)
68 {
69 	unsigned int val;
70 	int i;
71 
72 	for (i = 0, val = 0; (i < 8); i++) {
73 		val |= (((get_dp() & RTC_IODATA) ? 1 : 0) << i);
74 		set_dp(get_dp() | RTC_SCLK);	/* clock high */
75 		set_dp(get_dp() & ~RTC_SCLK);	/* clock low */
76 	}
77 
78 	return val;
79 }
80 
81 static unsigned int ds1302_readbyte(unsigned int addr)
82 {
83 	unsigned int val;
84 
85 	set_dp(get_dp() & ~(RTC_RESET | RTC_IODATA | RTC_SCLK));
86 
87 	set_dp(get_dp() | RTC_RESET);
88 	ds1302_sendbits(((addr & 0x3f) << 1) | RTC_CMD_READ);
89 	val = ds1302_recvbits();
90 	set_dp(get_dp() & ~RTC_RESET);
91 
92 	return val;
93 }
94 
95 static void ds1302_writebyte(unsigned int addr, unsigned int val)
96 {
97 	set_dp(get_dp() & ~(RTC_RESET | RTC_IODATA | RTC_SCLK));
98 	set_dp(get_dp() | RTC_RESET);
99 	ds1302_sendbits(((addr & 0x3f) << 1) | RTC_CMD_WRITE);
100 	ds1302_sendbits(val);
101 	set_dp(get_dp() & ~RTC_RESET);
102 }
103 
104 static int ds1302_rtc_read_time(struct device *dev, struct rtc_time *tm)
105 {
106 	struct ds1302_rtc *rtc = dev_get_drvdata(dev);
107 
108 	spin_lock_irq(&rtc->lock);
109 
110 	tm->tm_sec	= BCD2BIN(ds1302_readbyte(RTC_ADDR_SEC));
111 	tm->tm_min	= BCD2BIN(ds1302_readbyte(RTC_ADDR_MIN));
112 	tm->tm_hour	= BCD2BIN(ds1302_readbyte(RTC_ADDR_HOUR));
113 	tm->tm_wday	= BCD2BIN(ds1302_readbyte(RTC_ADDR_DAY));
114 	tm->tm_mday	= BCD2BIN(ds1302_readbyte(RTC_ADDR_DATE));
115 	tm->tm_mon	= BCD2BIN(ds1302_readbyte(RTC_ADDR_MON)) - 1;
116 	tm->tm_year	= BCD2BIN(ds1302_readbyte(RTC_ADDR_YEAR));
117 
118 	if (tm->tm_year < 70)
119 		tm->tm_year += 100;
120 
121 	spin_unlock_irq(&rtc->lock);
122 
123 	dev_dbg(dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
124 		"mday=%d, mon=%d, year=%d, wday=%d\n",
125 		__func__,
126 		tm->tm_sec, tm->tm_min, tm->tm_hour,
127 		tm->tm_mday, tm->tm_mon + 1, tm->tm_year, tm->tm_wday);
128 
129 	if (rtc_valid_tm(tm) < 0)
130 		dev_err(dev, "invalid date\n");
131 
132 	return 0;
133 }
134 
135 static int ds1302_rtc_set_time(struct device *dev, struct rtc_time *tm)
136 {
137 	struct ds1302_rtc *rtc = dev_get_drvdata(dev);
138 
139 	spin_lock_irq(&rtc->lock);
140 
141 	/* Stop RTC */
142 	ds1302_writebyte(RTC_ADDR_SEC, ds1302_readbyte(RTC_ADDR_SEC) | 0x80);
143 
144 	ds1302_writebyte(RTC_ADDR_SEC, BIN2BCD(tm->tm_sec));
145 	ds1302_writebyte(RTC_ADDR_MIN, BIN2BCD(tm->tm_min));
146 	ds1302_writebyte(RTC_ADDR_HOUR, BIN2BCD(tm->tm_hour));
147 	ds1302_writebyte(RTC_ADDR_DAY, BIN2BCD(tm->tm_wday));
148 	ds1302_writebyte(RTC_ADDR_DATE, BIN2BCD(tm->tm_mday));
149 	ds1302_writebyte(RTC_ADDR_MON, BIN2BCD(tm->tm_mon + 1));
150 	ds1302_writebyte(RTC_ADDR_YEAR, BIN2BCD(tm->tm_year % 100));
151 
152 	/* Start RTC */
153 	ds1302_writebyte(RTC_ADDR_SEC, ds1302_readbyte(RTC_ADDR_SEC) & ~0x80);
154 
155 	spin_unlock_irq(&rtc->lock);
156 
157 	return 0;
158 }
159 
160 static int ds1302_rtc_ioctl(struct device *dev, unsigned int cmd,
161 			    unsigned long arg)
162 {
163 	switch (cmd) {
164 #ifdef RTC_SET_CHARGE
165 	case RTC_SET_CHARGE:
166 	{
167 		struct ds1302_rtc *rtc = dev_get_drvdata(dev);
168 		int tcs_val;
169 
170 		if (copy_from_user(&tcs_val, (int __user *)arg, sizeof(int)))
171 			return -EFAULT;
172 
173 		spin_lock_irq(&rtc->lock);
174 		ds1302_writebyte(RTC_ADDR_TCR, (0xa0 | tcs_val * 0xf));
175 		spin_unlock_irq(&rtc->lock);
176 		return 0;
177 	}
178 #endif
179 	}
180 
181 	return -ENOIOCTLCMD;
182 }
183 
184 static struct rtc_class_ops ds1302_rtc_ops = {
185 	.read_time	= ds1302_rtc_read_time,
186 	.set_time	= ds1302_rtc_set_time,
187 	.ioctl		= ds1302_rtc_ioctl,
188 };
189 
190 static int __devinit ds1302_rtc_probe(struct platform_device *pdev)
191 {
192 	struct ds1302_rtc *rtc;
193 	int ret;
194 
195 	/* Reset */
196 	set_dp(get_dp() & ~(RTC_RESET | RTC_IODATA | RTC_SCLK));
197 
198 	/* Write a magic value to the DS1302 RAM, and see if it sticks. */
199 	ds1302_writebyte(RTC_ADDR_RAM0, 0x42);
200 	if (ds1302_readbyte(RTC_ADDR_RAM0) != 0x42)
201 		return -ENODEV;
202 
203 	rtc = kzalloc(sizeof(struct ds1302_rtc), GFP_KERNEL);
204 	if (unlikely(!rtc))
205 		return -ENOMEM;
206 
207 	spin_lock_init(&rtc->lock);
208 	rtc->rtc_dev = rtc_device_register("ds1302", &pdev->dev,
209 					   &ds1302_rtc_ops, THIS_MODULE);
210 	if (IS_ERR(rtc->rtc_dev)) {
211 		ret = PTR_ERR(rtc->rtc_dev);
212 		goto out;
213 	}
214 
215 	platform_set_drvdata(pdev, rtc);
216 
217 	return 0;
218 out:
219 	kfree(rtc);
220 	return ret;
221 }
222 
223 static int __devexit ds1302_rtc_remove(struct platform_device *pdev)
224 {
225 	struct ds1302_rtc *rtc = platform_get_drvdata(pdev);
226 
227 	if (likely(rtc->rtc_dev))
228 		rtc_device_unregister(rtc->rtc_dev);
229 
230 	platform_set_drvdata(pdev, NULL);
231 
232 	kfree(rtc);
233 
234 	return 0;
235 }
236 
237 static struct platform_driver ds1302_platform_driver = {
238 	.driver		= {
239 		.name	= DRV_NAME,
240 		.owner	= THIS_MODULE,
241 	},
242 	.probe		= ds1302_rtc_probe,
243 	.remove		= __devexit_p(ds1302_rtc_remove),
244 };
245 
246 static int __init ds1302_rtc_init(void)
247 {
248 	return platform_driver_register(&ds1302_platform_driver);
249 }
250 
251 static void __exit ds1302_rtc_exit(void)
252 {
253 	platform_driver_unregister(&ds1302_platform_driver);
254 }
255 
256 module_init(ds1302_rtc_init);
257 module_exit(ds1302_rtc_exit);
258 
259 MODULE_DESCRIPTION("Dallas DS1302 RTC driver");
260 MODULE_VERSION(DRV_VERSION);
261 MODULE_AUTHOR("Paul Mundt, David McCullough");
262 MODULE_LICENSE("GPL v2");
263