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Linux/drivers/rtc/rtc-ds1302.c

  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 
 12 #include <linux/init.h>
 13 #include <linux/module.h>
 14 #include <linux/kernel.h>
 15 #include <linux/platform_device.h>
 16 #include <linux/rtc.h>
 17 #include <linux/io.h>
 18 #include <linux/bcd.h>
 19 
 20 #define DRV_NAME        "rtc-ds1302"
 21 #define DRV_VERSION     "0.1.1"
 22 
 23 #define RTC_CMD_READ    0x81            /* Read command */
 24 #define RTC_CMD_WRITE   0x80            /* Write command */
 25 
 26 #define RTC_CMD_WRITE_ENABLE    0x00            /* Write enable */
 27 #define RTC_CMD_WRITE_DISABLE   0x80            /* Write disable */
 28 
 29 #define RTC_ADDR_RAM0   0x20            /* Address of RAM0 */
 30 #define RTC_ADDR_TCR    0x08            /* Address of trickle charge register */
 31 #define RTC_ADDR_CTRL   0x07            /* Address of control register */
 32 #define RTC_ADDR_YEAR   0x06            /* Address of year register */
 33 #define RTC_ADDR_DAY    0x05            /* Address of day of week register */
 34 #define RTC_ADDR_MON    0x04            /* Address of month register */
 35 #define RTC_ADDR_DATE   0x03            /* Address of day of month register */
 36 #define RTC_ADDR_HOUR   0x02            /* Address of hour register */
 37 #define RTC_ADDR_MIN    0x01            /* Address of minute register */
 38 #define RTC_ADDR_SEC    0x00            /* Address of second register */
 39 
 40 #ifdef CONFIG_SH_SECUREEDGE5410
 41 #include <asm/rtc.h>
 42 #include <mach/secureedge5410.h>
 43 
 44 #define RTC_RESET       0x1000
 45 #define RTC_IODATA      0x0800
 46 #define RTC_SCLK        0x0400
 47 
 48 #define set_dp(x)       SECUREEDGE_WRITE_IOPORT(x, 0x1c00)
 49 #define get_dp()        SECUREEDGE_READ_IOPORT()
 50 #define ds1302_set_tx()
 51 #define ds1302_set_rx()
 52 
 53 static inline int ds1302_hw_init(void)
 54 {
 55         return 0;
 56 }
 57 
 58 static inline void ds1302_reset(void)
 59 {
 60         set_dp(get_dp() & ~(RTC_RESET | RTC_IODATA | RTC_SCLK));
 61 }
 62 
 63 static inline void ds1302_clock(void)
 64 {
 65         set_dp(get_dp() | RTC_SCLK);    /* clock high */
 66         set_dp(get_dp() & ~RTC_SCLK);   /* clock low */
 67 }
 68 
 69 static inline void ds1302_start(void)
 70 {
 71         set_dp(get_dp() | RTC_RESET);
 72 }
 73 
 74 static inline void ds1302_stop(void)
 75 {
 76         set_dp(get_dp() & ~RTC_RESET);
 77 }
 78 
 79 static inline void ds1302_txbit(int bit)
 80 {
 81         set_dp((get_dp() & ~RTC_IODATA) | (bit ? RTC_IODATA : 0));
 82 }
 83 
 84 static inline int ds1302_rxbit(void)
 85 {
 86         return !!(get_dp() & RTC_IODATA);
 87 }
 88 
 89 #else
 90 #error "Add support for your platform"
 91 #endif
 92 
 93 static void ds1302_sendbits(unsigned int val)
 94 {
 95         int i;
 96 
 97         ds1302_set_tx();
 98 
 99         for (i = 8; (i); i--, val >>= 1) {
100                 ds1302_txbit(val & 0x1);
101                 ds1302_clock();
102         }
103 }
104 
105 static unsigned int ds1302_recvbits(void)
106 {
107         unsigned int val;
108         int i;
109 
110         ds1302_set_rx();
111 
112         for (i = 0, val = 0; (i < 8); i++) {
113                 val |= (ds1302_rxbit() << i);
114                 ds1302_clock();
115         }
116 
117         return val;
118 }
119 
120 static unsigned int ds1302_readbyte(unsigned int addr)
121 {
122         unsigned int val;
123 
124         ds1302_reset();
125 
126         ds1302_start();
127         ds1302_sendbits(((addr & 0x3f) << 1) | RTC_CMD_READ);
128         val = ds1302_recvbits();
129         ds1302_stop();
130 
131         return val;
132 }
133 
134 static void ds1302_writebyte(unsigned int addr, unsigned int val)
135 {
136         ds1302_reset();
137 
138         ds1302_start();
139         ds1302_sendbits(((addr & 0x3f) << 1) | RTC_CMD_WRITE);
140         ds1302_sendbits(val);
141         ds1302_stop();
142 }
143 
144 static int ds1302_rtc_read_time(struct device *dev, struct rtc_time *tm)
145 {
146         tm->tm_sec      = bcd2bin(ds1302_readbyte(RTC_ADDR_SEC));
147         tm->tm_min      = bcd2bin(ds1302_readbyte(RTC_ADDR_MIN));
148         tm->tm_hour     = bcd2bin(ds1302_readbyte(RTC_ADDR_HOUR));
149         tm->tm_wday     = bcd2bin(ds1302_readbyte(RTC_ADDR_DAY));
150         tm->tm_mday     = bcd2bin(ds1302_readbyte(RTC_ADDR_DATE));
151         tm->tm_mon      = bcd2bin(ds1302_readbyte(RTC_ADDR_MON)) - 1;
152         tm->tm_year     = bcd2bin(ds1302_readbyte(RTC_ADDR_YEAR));
153 
154         if (tm->tm_year < 70)
155                 tm->tm_year += 100;
156 
157         dev_dbg(dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
158                 "mday=%d, mon=%d, year=%d, wday=%d\n",
159                 __func__,
160                 tm->tm_sec, tm->tm_min, tm->tm_hour,
161                 tm->tm_mday, tm->tm_mon + 1, tm->tm_year, tm->tm_wday);
162 
163         return rtc_valid_tm(tm);
164 }
165 
166 static int ds1302_rtc_set_time(struct device *dev, struct rtc_time *tm)
167 {
168         ds1302_writebyte(RTC_ADDR_CTRL, RTC_CMD_WRITE_ENABLE);
169         /* Stop RTC */
170         ds1302_writebyte(RTC_ADDR_SEC, ds1302_readbyte(RTC_ADDR_SEC) | 0x80);
171 
172         ds1302_writebyte(RTC_ADDR_SEC, bin2bcd(tm->tm_sec));
173         ds1302_writebyte(RTC_ADDR_MIN, bin2bcd(tm->tm_min));
174         ds1302_writebyte(RTC_ADDR_HOUR, bin2bcd(tm->tm_hour));
175         ds1302_writebyte(RTC_ADDR_DAY, bin2bcd(tm->tm_wday));
176         ds1302_writebyte(RTC_ADDR_DATE, bin2bcd(tm->tm_mday));
177         ds1302_writebyte(RTC_ADDR_MON, bin2bcd(tm->tm_mon + 1));
178         ds1302_writebyte(RTC_ADDR_YEAR, bin2bcd(tm->tm_year % 100));
179 
180         /* Start RTC */
181         ds1302_writebyte(RTC_ADDR_SEC, ds1302_readbyte(RTC_ADDR_SEC) & ~0x80);
182 
183         ds1302_writebyte(RTC_ADDR_CTRL, RTC_CMD_WRITE_DISABLE);
184 
185         return 0;
186 }
187 
188 static int ds1302_rtc_ioctl(struct device *dev, unsigned int cmd,
189                             unsigned long arg)
190 {
191         switch (cmd) {
192 #ifdef RTC_SET_CHARGE
193         case RTC_SET_CHARGE:
194         {
195                 int tcs_val;
196 
197                 if (copy_from_user(&tcs_val, (int __user *)arg, sizeof(int)))
198                         return -EFAULT;
199 
200                 ds1302_writebyte(RTC_ADDR_TCR, (0xa0 | tcs_val * 0xf));
201                 return 0;
202         }
203 #endif
204         }
205 
206         return -ENOIOCTLCMD;
207 }
208 
209 static struct rtc_class_ops ds1302_rtc_ops = {
210         .read_time      = ds1302_rtc_read_time,
211         .set_time       = ds1302_rtc_set_time,
212         .ioctl          = ds1302_rtc_ioctl,
213 };
214 
215 static int __init ds1302_rtc_probe(struct platform_device *pdev)
216 {
217         struct rtc_device *rtc;
218 
219         if (ds1302_hw_init()) {
220                 dev_err(&pdev->dev, "Failed to init communication channel");
221                 return -EINVAL;
222         }
223 
224         /* Reset */
225         ds1302_reset();
226 
227         /* Write a magic value to the DS1302 RAM, and see if it sticks. */
228         ds1302_writebyte(RTC_ADDR_RAM0, 0x42);
229         if (ds1302_readbyte(RTC_ADDR_RAM0) != 0x42) {
230                 dev_err(&pdev->dev, "Failed to probe");
231                 return -ENODEV;
232         }
233 
234         rtc = devm_rtc_device_register(&pdev->dev, "ds1302",
235                                            &ds1302_rtc_ops, THIS_MODULE);
236         if (IS_ERR(rtc))
237                 return PTR_ERR(rtc);
238 
239         platform_set_drvdata(pdev, rtc);
240 
241         return 0;
242 }
243 
244 static struct platform_driver ds1302_platform_driver = {
245         .driver         = {
246                 .name   = DRV_NAME,
247                 .owner  = THIS_MODULE,
248         },
249 };
250 
251 module_platform_driver_probe(ds1302_platform_driver, ds1302_rtc_probe);
252 
253 MODULE_DESCRIPTION("Dallas DS1302 RTC driver");
254 MODULE_VERSION(DRV_VERSION);
255 MODULE_AUTHOR("Paul Mundt, David McCullough");
256 MODULE_LICENSE("GPL v2");
257 

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