summaryrefslogtreecommitdiff
path: root/drivers/acorn/char/i2c.c
blob: 9e584a7af434eec943908eeaa97477e2b0b80f06 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
/*
 *  linux/drivers/acorn/char/i2c.c
 *
 *  Copyright (C) 2000 Russell King
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 *  ARM IOC/IOMD i2c driver.
 *
 *  On Acorn machines, the following i2c devices are on the bus:
 *	- PCF8583 real time clock & static RAM
 */
#include <linux/capability.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/time.h>
#include <linux/miscdevice.h>
#include <linux/rtc.h>
#include <linux/i2c.h>
#include <linux/i2c-algo-bit.h>
#include <linux/fs.h>

#include <asm/hardware.h>
#include <asm/io.h>
#include <asm/hardware/ioc.h>
#include <asm/system.h>
#include <asm/uaccess.h>

#include "pcf8583.h"

extern int (*set_rtc)(void);

static struct i2c_client *rtc_client;
static const unsigned char days_in_mon[] = 
	{ 0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };

#define CMOS_CHECKSUM	(63)

/*
 * Acorn machines store the year in the static RAM at
 * location 128.
 */
#define CMOS_YEAR	(64 + 128)

static inline int rtc_command(int cmd, void *data)
{
	int ret = -EIO;

	if (rtc_client)
		ret = rtc_client->driver->command(rtc_client, cmd, data);

	return ret;
}

/*
 * Update the century + year bytes in the CMOS RAM, ensuring
 * that the check byte is correctly adjusted for the change.
 */
static int rtc_update_year(unsigned int new_year)
{
	unsigned char yr[2], chk;
	struct mem cmos_year  = { CMOS_YEAR, sizeof(yr), yr };
	struct mem cmos_check = { CMOS_CHECKSUM, 1, &chk };
	int ret;

	ret = rtc_command(MEM_READ, &cmos_check);
	if (ret)
		goto out;
	ret = rtc_command(MEM_READ, &cmos_year);
	if (ret)
		goto out;

	chk -= yr[1] + yr[0];

	yr[1] = new_year / 100;
	yr[0] = new_year % 100;

	chk += yr[1] + yr[0];

	ret = rtc_command(MEM_WRITE, &cmos_year);
	if (ret == 0)
		ret = rtc_command(MEM_WRITE, &cmos_check);
 out:
	return ret;
}

/*
 * Read the current RTC time and date, and update xtime.
 */
static void get_rtc_time(struct rtc_tm *rtctm, unsigned int *year)
{
	unsigned char ctrl, yr[2];
	struct mem rtcmem = { CMOS_YEAR, sizeof(yr), yr };
	int real_year, year_offset;

	/*
	 * Ensure that the RTC is running.
	 */
	rtc_command(RTC_GETCTRL, &ctrl);
	if (ctrl & 0xc0) {
		unsigned char new_ctrl = ctrl & ~0xc0;

		printk(KERN_WARNING "RTC: resetting control %02x -> %02x\n",
		       ctrl, new_ctrl);

		rtc_command(RTC_SETCTRL, &new_ctrl);
	}

	if (rtc_command(RTC_GETDATETIME, rtctm) ||
	    rtc_command(MEM_READ, &rtcmem))
		return;

	real_year = yr[0];

	/*
	 * The RTC year holds the LSB two bits of the current
	 * year, which should reflect the LSB two bits of the
	 * CMOS copy of the year.  Any difference indicates
	 * that we have to correct the CMOS version.
	 */
	year_offset = rtctm->year_off - (real_year & 3);
	if (year_offset < 0)
		/*
		 * RTC year wrapped.  Adjust it appropriately.
		 */
		year_offset += 4;

	*year = real_year + year_offset + yr[1] * 100;
}

static int set_rtc_time(struct rtc_tm *rtctm, unsigned int year)
{
	unsigned char leap;
	int ret;

	leap = (!(year % 4) && (year % 100)) || !(year % 400);

	if (rtctm->mon > 12 || rtctm->mon == 0 || rtctm->mday == 0)
		return -EINVAL;

	if (rtctm->mday > (days_in_mon[rtctm->mon] + (rtctm->mon == 2 && leap)))
		return -EINVAL;

	if (rtctm->hours >= 24 || rtctm->mins >= 60 || rtctm->secs >= 60)
		return -EINVAL;

	/*
	 * The RTC's own 2-bit year must reflect the least
	 * significant two bits of the CMOS year.
	 */
	rtctm->year_off = (year % 100) & 3;

	ret = rtc_command(RTC_SETDATETIME, rtctm);
	if (ret == 0)
		ret = rtc_update_year(year);

	return ret;
}

/*
 * Set the RTC time only.  Note that
 * we do not touch the date.
 */
static int k_set_rtc_time(void)
{
	struct rtc_tm new_rtctm, old_rtctm;
	unsigned long nowtime = xtime.tv_sec;

	if (rtc_command(RTC_GETDATETIME, &old_rtctm))
		return 0;

	new_rtctm.cs    = xtime.tv_nsec / 10000000;
	new_rtctm.secs  = nowtime % 60;	nowtime /= 60;
	new_rtctm.mins  = nowtime % 60;	nowtime /= 60;
	new_rtctm.hours = nowtime % 24;

	/*
	 * avoid writing when we're going to change the day
	 * of the month.  We will retry in the next minute.
	 * This basically means that if the RTC must not drift
	 * by more than 1 minute in 11 minutes.
	 *
	 * [ rtc: 1/1/2000 23:58:00, real 2/1/2000 00:01:00,
	 *   rtc gets set to 1/1/2000 00:01:00 ]
	 */
	if ((old_rtctm.hours == 23 && old_rtctm.mins == 59) ||
	    (new_rtctm.hours == 23 && new_rtctm.mins == 59))
		return 1;

	return rtc_command(RTC_SETTIME, &new_rtctm);
}

static int rtc_ioctl(struct inode *inode, struct file *file,
		     unsigned int cmd, unsigned long arg)
{
	unsigned int year;
	struct rtc_time rtctm;
	struct rtc_tm rtc_raw;

	switch (cmd) {
	case RTC_ALM_READ:
	case RTC_ALM_SET:
		break;

	case RTC_RD_TIME:
		memset(&rtctm, 0, sizeof(struct rtc_time));
		get_rtc_time(&rtc_raw, &year);
		rtctm.tm_sec  = rtc_raw.secs;
		rtctm.tm_min  = rtc_raw.mins;
		rtctm.tm_hour = rtc_raw.hours;
		rtctm.tm_mday = rtc_raw.mday;
		rtctm.tm_mon  = rtc_raw.mon - 1; /* month starts at 0 */
		rtctm.tm_year = year - 1900; /* starts at 1900 */
		return copy_to_user((void *)arg, &rtctm, sizeof(rtctm))
				 ? -EFAULT : 0;

	case RTC_SET_TIME:
		if (!capable(CAP_SYS_TIME))
			return -EACCES;

		if (copy_from_user(&rtctm, (void *)arg, sizeof(rtctm)))
			return -EFAULT;
		rtc_raw.secs     = rtctm.tm_sec;
		rtc_raw.mins     = rtctm.tm_min;
		rtc_raw.hours    = rtctm.tm_hour;
		rtc_raw.mday     = rtctm.tm_mday;
		rtc_raw.mon      = rtctm.tm_mon + 1;
		year             = rtctm.tm_year + 1900;
		return set_rtc_time(&rtc_raw, year);
		break;

	case RTC_EPOCH_READ:
		return put_user(1900, (unsigned long *)arg);

	}
	return -EINVAL;
}

static struct file_operations rtc_fops = {
	.ioctl	= rtc_ioctl,
};

static struct miscdevice rtc_dev = {
	.minor	= RTC_MINOR,
	.name	= "rtc",
	.fops	= &rtc_fops,
};

/* IOC / IOMD i2c driver */

#define FORCE_ONES	0xdc
#define SCL		0x02
#define SDA		0x01

/*
 * We must preserve all non-i2c output bits in IOC_CONTROL.
 * Note also that we need to preserve the value of SCL and
 * SDA outputs as well (which may be different from the
 * values read back from IOC_CONTROL).
 */
static u_int force_ones;

static void ioc_setscl(void *data, int state)
{
	u_int ioc_control = ioc_readb(IOC_CONTROL) & ~(SCL | SDA);
	u_int ones = force_ones;

	if (state)
		ones |= SCL;
	else
		ones &= ~SCL;

	force_ones = ones;

 	ioc_writeb(ioc_control | ones, IOC_CONTROL);
}

static void ioc_setsda(void *data, int state)
{
	u_int ioc_control = ioc_readb(IOC_CONTROL) & ~(SCL | SDA);
	u_int ones = force_ones;

	if (state)
		ones |= SDA;
	else
		ones &= ~SDA;

	force_ones = ones;

 	ioc_writeb(ioc_control | ones, IOC_CONTROL);
}

static int ioc_getscl(void *data)
{
	return (ioc_readb(IOC_CONTROL) & SCL) != 0;
}

static int ioc_getsda(void *data)
{
	return (ioc_readb(IOC_CONTROL) & SDA) != 0;
}

static struct i2c_algo_bit_data ioc_data = {
	.setsda		= ioc_setsda,
	.setscl		= ioc_setscl,
	.getsda		= ioc_getsda,
	.getscl		= ioc_getscl,
	.udelay		= 80,
	.timeout	= 100
};

static int ioc_client_reg(struct i2c_client *client)
{
	if (client->driver->id == I2C_DRIVERID_PCF8583 &&
	    client->addr == 0x50) {
		struct rtc_tm rtctm;
		unsigned int year;
		struct timespec tv;

		rtc_client = client;
		get_rtc_time(&rtctm, &year);

		tv.tv_nsec = rtctm.cs * 10000000;
		tv.tv_sec  = mktime(year, rtctm.mon, rtctm.mday,
				    rtctm.hours, rtctm.mins, rtctm.secs);
		do_settimeofday(&tv);
		set_rtc = k_set_rtc_time;
	}

	return 0;
}

static int ioc_client_unreg(struct i2c_client *client)
{
	if (client == rtc_client) {
		set_rtc = NULL;
		rtc_client = NULL;
	}

	return 0;
}

static struct i2c_adapter ioc_ops = {
	.id			= I2C_HW_B_IOC,
	.algo_data		= &ioc_data,
	.client_register	= ioc_client_reg,
	.client_unregister	= ioc_client_unreg,
};

static int __init i2c_ioc_init(void)
{
	int ret;

	force_ones = FORCE_ONES | SCL | SDA;

	ret = i2c_bit_add_bus(&ioc_ops);

	if (ret >= 0){
		ret = misc_register(&rtc_dev);
		if(ret < 0)
			i2c_del_adapter(&ioc_ops);
	}

	return ret;
}

__initcall(i2c_ioc_init);