Root/drivers/char/ds1302.c

1/*!***************************************************************************
2*!
3*! FILE NAME : ds1302.c
4*!
5*! DESCRIPTION: Implements an interface for the DS1302 RTC
6*!
7*! Functions exported: ds1302_readreg, ds1302_writereg, ds1302_init, get_rtc_status
8*!
9*! ---------------------------------------------------------------------------
10*!
11*! (C) Copyright 1999, 2000, 2001 Axis Communications AB, LUND, SWEDEN
12*!
13*!***************************************************************************/
14
15
16#include <linux/fs.h>
17#include <linux/init.h>
18#include <linux/mm.h>
19#include <linux/module.h>
20#include <linux/miscdevice.h>
21#include <linux/delay.h>
22#include <linux/bcd.h>
23#include <linux/mutex.h>
24#include <linux/uaccess.h>
25#include <linux/io.h>
26
27#include <asm/rtc.h>
28#if defined(CONFIG_M32R)
29#include <asm/m32r.h>
30#endif
31
32#define RTC_MAJOR_NR 121 /* local major, change later */
33
34static DEFINE_MUTEX(rtc_mutex);
35static const char ds1302_name[] = "ds1302";
36
37/* Send 8 bits. */
38static void
39out_byte_rtc(unsigned int reg_addr, unsigned char x)
40{
41    //RST H
42    outw(0x0001,(unsigned long)PLD_RTCRSTODT);
43    //write data
44    outw(((x<<8)|(reg_addr&0xff)),(unsigned long)PLD_RTCWRDATA);
45    //WE
46    outw(0x0002,(unsigned long)PLD_RTCCR);
47    //wait
48    while(inw((unsigned long)PLD_RTCCR));
49
50    //RST L
51    outw(0x0000,(unsigned long)PLD_RTCRSTODT);
52
53}
54
55static unsigned char
56in_byte_rtc(unsigned int reg_addr)
57{
58    unsigned char retval;
59
60    //RST H
61    outw(0x0001,(unsigned long)PLD_RTCRSTODT);
62    //write data
63    outw((reg_addr&0xff),(unsigned long)PLD_RTCRDDATA);
64    //RE
65    outw(0x0001,(unsigned long)PLD_RTCCR);
66    //wait
67    while(inw((unsigned long)PLD_RTCCR));
68
69    //read data
70    retval=(inw((unsigned long)PLD_RTCRDDATA) & 0xff00)>>8;
71
72    //RST L
73    outw(0x0000,(unsigned long)PLD_RTCRSTODT);
74
75    return retval;
76}
77
78/* Enable writing. */
79
80static void
81ds1302_wenable(void)
82{
83    out_byte_rtc(0x8e,0x00);
84}
85
86/* Disable writing. */
87
88static void
89ds1302_wdisable(void)
90{
91    out_byte_rtc(0x8e,0x80);
92}
93
94
95
96/* Read a byte from the selected register in the DS1302. */
97
98unsigned char
99ds1302_readreg(int reg)
100{
101    unsigned char x;
102
103    x=in_byte_rtc((0x81 | (reg << 1))); /* read register */
104
105    return x;
106}
107
108/* Write a byte to the selected register. */
109
110void
111ds1302_writereg(int reg, unsigned char val)
112{
113    ds1302_wenable();
114    out_byte_rtc((0x80 | (reg << 1)),val);
115    ds1302_wdisable();
116}
117
118void
119get_rtc_time(struct rtc_time *rtc_tm)
120{
121    unsigned long flags;
122
123    local_irq_save(flags);
124
125    rtc_tm->tm_sec = CMOS_READ(RTC_SECONDS);
126    rtc_tm->tm_min = CMOS_READ(RTC_MINUTES);
127    rtc_tm->tm_hour = CMOS_READ(RTC_HOURS);
128    rtc_tm->tm_mday = CMOS_READ(RTC_DAY_OF_MONTH);
129    rtc_tm->tm_mon = CMOS_READ(RTC_MONTH);
130    rtc_tm->tm_year = CMOS_READ(RTC_YEAR);
131
132    local_irq_restore(flags);
133
134    rtc_tm->tm_sec = bcd2bin(rtc_tm->tm_sec);
135    rtc_tm->tm_min = bcd2bin(rtc_tm->tm_min);
136    rtc_tm->tm_hour = bcd2bin(rtc_tm->tm_hour);
137    rtc_tm->tm_mday = bcd2bin(rtc_tm->tm_mday);
138    rtc_tm->tm_mon = bcd2bin(rtc_tm->tm_mon);
139    rtc_tm->tm_year = bcd2bin(rtc_tm->tm_year);
140
141    /*
142     * Account for differences between how the RTC uses the values
143     * and how they are defined in a struct rtc_time;
144     */
145
146    if (rtc_tm->tm_year <= 69)
147        rtc_tm->tm_year += 100;
148
149    rtc_tm->tm_mon--;
150}
151
152static unsigned char days_in_mo[] =
153    {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
154
155/* ioctl that supports RTC_RD_TIME and RTC_SET_TIME (read and set time/date). */
156
157static long rtc_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
158{
159    unsigned long flags;
160
161    switch(cmd) {
162        case RTC_RD_TIME: /* read the time/date from RTC */
163        {
164            struct rtc_time rtc_tm;
165
166            memset(&rtc_tm, 0, sizeof (struct rtc_time));
167            mutex_lock(&rtc_mutex);
168            get_rtc_time(&rtc_tm);
169            mutex_unlock(&rtc_mutex);
170            if (copy_to_user((struct rtc_time*)arg, &rtc_tm, sizeof(struct rtc_time)))
171                return -EFAULT;
172            return 0;
173        }
174
175        case RTC_SET_TIME: /* set the RTC */
176        {
177            struct rtc_time rtc_tm;
178            unsigned char mon, day, hrs, min, sec, leap_yr;
179            unsigned int yrs;
180
181            if (!capable(CAP_SYS_TIME))
182                return -EPERM;
183
184            if (copy_from_user(&rtc_tm, (struct rtc_time*)arg, sizeof(struct rtc_time)))
185                return -EFAULT;
186
187            yrs = rtc_tm.tm_year + 1900;
188            mon = rtc_tm.tm_mon + 1; /* tm_mon starts at zero */
189            day = rtc_tm.tm_mday;
190            hrs = rtc_tm.tm_hour;
191            min = rtc_tm.tm_min;
192            sec = rtc_tm.tm_sec;
193
194
195            if ((yrs < 1970) || (yrs > 2069))
196                return -EINVAL;
197
198            leap_yr = ((!(yrs % 4) && (yrs % 100)) || !(yrs % 400));
199
200            if ((mon > 12) || (day == 0))
201                return -EINVAL;
202
203            if (day > (days_in_mo[mon] + ((mon == 2) && leap_yr)))
204                return -EINVAL;
205
206            if ((hrs >= 24) || (min >= 60) || (sec >= 60))
207                return -EINVAL;
208
209            if (yrs >= 2000)
210                yrs -= 2000; /* RTC (0, 1, ... 69) */
211            else
212                yrs -= 1900; /* RTC (70, 71, ... 99) */
213
214            sec = bin2bcd(sec);
215            min = bin2bcd(min);
216            hrs = bin2bcd(hrs);
217            day = bin2bcd(day);
218            mon = bin2bcd(mon);
219            yrs = bin2bcd(yrs);
220
221            mutex_lock(&rtc_mutex);
222            local_irq_save(flags);
223            CMOS_WRITE(yrs, RTC_YEAR);
224            CMOS_WRITE(mon, RTC_MONTH);
225            CMOS_WRITE(day, RTC_DAY_OF_MONTH);
226            CMOS_WRITE(hrs, RTC_HOURS);
227            CMOS_WRITE(min, RTC_MINUTES);
228            CMOS_WRITE(sec, RTC_SECONDS);
229            local_irq_restore(flags);
230            mutex_unlock(&rtc_mutex);
231
232            /* Notice that at this point, the RTC is updated but
233             * the kernel is still running with the old time.
234             * You need to set that separately with settimeofday
235             * or adjtimex.
236             */
237            return 0;
238        }
239
240        case RTC_SET_CHARGE: /* set the RTC TRICKLE CHARGE register */
241        {
242            int tcs_val;
243
244            if (!capable(CAP_SYS_TIME))
245                return -EPERM;
246
247            if(copy_from_user(&tcs_val, (int*)arg, sizeof(int)))
248                return -EFAULT;
249
250            mutex_lock(&rtc_mutex);
251            tcs_val = RTC_TCR_PATTERN | (tcs_val & 0x0F);
252            ds1302_writereg(RTC_TRICKLECHARGER, tcs_val);
253            mutex_unlock(&rtc_mutex);
254            return 0;
255        }
256        default:
257            return -EINVAL;
258    }
259}
260
261int
262get_rtc_status(char *buf)
263{
264    char *p;
265    struct rtc_time tm;
266
267    p = buf;
268
269    get_rtc_time(&tm);
270
271    /*
272     * There is no way to tell if the luser has the RTC set for local
273     * time or for Universal Standard Time (GMT). Probably local though.
274     */
275
276    p += sprintf(p,
277        "rtc_time\t: %02d:%02d:%02d\n"
278        "rtc_date\t: %04d-%02d-%02d\n",
279        tm.tm_hour, tm.tm_min, tm.tm_sec,
280        tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday);
281
282    return p - buf;
283}
284
285
286/* The various file operations we support. */
287
288static const struct file_operations rtc_fops = {
289    .owner = THIS_MODULE,
290    .unlocked_ioctl = rtc_ioctl,
291    .llseek = noop_llseek,
292};
293
294/* Probe for the chip by writing something to its RAM and try reading it back. */
295
296#define MAGIC_PATTERN 0x42
297
298static int __init
299ds1302_probe(void)
300{
301    int retval, res, baur;
302
303    baur=(boot_cpu_data.bus_clock/(2*1000*1000));
304
305    printk("%s: Set PLD_RTCBAUR = %d\n", ds1302_name,baur);
306
307    outw(0x0000,(unsigned long)PLD_RTCCR);
308    outw(0x0000,(unsigned long)PLD_RTCRSTODT);
309    outw(baur,(unsigned long)PLD_RTCBAUR);
310
311    /* Try to talk to timekeeper. */
312
313    ds1302_wenable();
314    /* write RAM byte 0 */
315    /* write something magic */
316    out_byte_rtc(0xc0,MAGIC_PATTERN);
317
318    /* read RAM byte 0 */
319    if((res = in_byte_rtc(0xc1)) == MAGIC_PATTERN) {
320        char buf[100];
321        ds1302_wdisable();
322        printk("%s: RTC found.\n", ds1302_name);
323        get_rtc_status(buf);
324        printk(buf);
325        retval = 1;
326    } else {
327        printk("%s: RTC not found.\n", ds1302_name);
328        retval = 0;
329    }
330
331    return retval;
332}
333
334
335/* Just probe for the RTC and register the device to handle the ioctl needed. */
336
337int __init
338ds1302_init(void)
339{
340    if (!ds1302_probe()) {
341        return -1;
342      }
343    return 0;
344}
345
346static int __init ds1302_register(void)
347{
348    ds1302_init();
349    if (register_chrdev(RTC_MAJOR_NR, ds1302_name, &rtc_fops)) {
350        printk(KERN_INFO "%s: unable to get major %d for rtc\n",
351               ds1302_name, RTC_MAJOR_NR);
352        return -1;
353    }
354    return 0;
355}
356
357module_init(ds1302_register);
358

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