i2c-algo-bit.c 16.2 KB
Newer Older
1 2 3 4
/* -------------------------------------------------------------------------
 * i2c-algo-bit.c i2c driver algorithms for bit-shift adapters
 * -------------------------------------------------------------------------
 *   Copyright (C) 1995-2000 Simon G. Vogl
L
Linus Torvalds 已提交
5 6 7 8 9 10 11 12 13 14 15 16 17

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
18 19
    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 * ------------------------------------------------------------------------- */
L
Linus Torvalds 已提交
20

21
/* With some changes from Frodo Looijaard <frodol@dds.nl>, Kyösti Mälkki
L
Linus Torvalds 已提交
22 23 24 25 26 27 28 29 30 31 32 33 34 35
   <kmalkki@cc.hut.fi> and Jean Delvare <khali@linux-fr.org> */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/i2c.h>
#include <linux/i2c-algo-bit.h>


/* ----- global defines ----------------------------------------------- */

J
Jean Delvare 已提交
36 37 38 39 40 41 42 43 44 45
#ifdef DEBUG
#define bit_dbg(level, dev, format, args...) \
	do { \
		if (i2c_debug >= level) \
			dev_dbg(dev, format, ##args); \
	} while (0)
#else
#define bit_dbg(level, dev, format, args...) \
	do {} while (0)
#endif /* DEBUG */
L
Linus Torvalds 已提交
46 47 48 49

/* ----- global variables ---------------------------------------------	*/

static int bit_test;	/* see if the line-setting functions work	*/
J
Jean Delvare 已提交
50 51 52 53 54 55 56 57 58
module_param(bit_test, bool, 0);
MODULE_PARM_DESC(bit_test, "Test the lines of the bus to see if it is stuck");

#ifdef DEBUG
static int i2c_debug = 1;
module_param(i2c_debug, int, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(i2c_debug,
		 "debug level - 0 off; 1 normal; 2 verbose; 3 very verbose");
#endif
L
Linus Torvalds 已提交
59 60 61

/* --- setting states on the bus with the right timing: ---------------	*/

62 63 64 65
#define setsda(adap, val)	adap->setsda(adap->data, val)
#define setscl(adap, val)	adap->setscl(adap->data, val)
#define getsda(adap)		adap->getsda(adap->data)
#define getscl(adap)		adap->getscl(adap->data)
L
Linus Torvalds 已提交
66 67 68

static inline void sdalo(struct i2c_algo_bit_data *adap)
{
69
	setsda(adap, 0);
70
	udelay((adap->udelay + 1) / 2);
L
Linus Torvalds 已提交
71 72 73 74
}

static inline void sdahi(struct i2c_algo_bit_data *adap)
{
75
	setsda(adap, 1);
76
	udelay((adap->udelay + 1) / 2);
L
Linus Torvalds 已提交
77 78 79 80
}

static inline void scllo(struct i2c_algo_bit_data *adap)
{
81
	setscl(adap, 0);
82
	udelay(adap->udelay / 2);
L
Linus Torvalds 已提交
83 84 85 86 87 88
}

/*
 * Raise scl line, and do checking for delays. This is necessary for slower
 * devices.
 */
J
Jean Delvare 已提交
89
static int sclhi(struct i2c_algo_bit_data *adap)
L
Linus Torvalds 已提交
90 91 92
{
	unsigned long start;

93
	setscl(adap, 1);
L
Linus Torvalds 已提交
94 95

	/* Not all adapters have scl sense line... */
J
Jean Delvare 已提交
96 97
	if (!adap->getscl)
		goto done;
L
Linus Torvalds 已提交
98

99 100 101 102 103 104 105
	start = jiffies;
	while (!getscl(adap)) {
		/* This hw knows how to read the clock line, so we wait
		 * until it actually gets high.  This is safer as some
		 * chips may hold it low ("clock stretching") while they
		 * are processing data internally.
		 */
D
Dave Airlie 已提交
106
		if (time_after(jiffies, start + adap->timeout))
L
Linus Torvalds 已提交
107 108 109
			return -ETIMEDOUT;
		cond_resched();
	}
J
Jean Delvare 已提交
110 111 112 113 114
#ifdef DEBUG
	if (jiffies != start && i2c_debug >= 3)
		pr_debug("i2c-algo-bit: needed %ld jiffies for SCL to go "
			 "high\n", jiffies - start);
#endif
J
Jean Delvare 已提交
115 116

done:
L
Linus Torvalds 已提交
117 118
	udelay(adap->udelay);
	return 0;
119
}
L
Linus Torvalds 已提交
120 121 122


/* --- other auxiliary functions --------------------------------------	*/
123
static void i2c_start(struct i2c_algo_bit_data *adap)
L
Linus Torvalds 已提交
124 125
{
	/* assert: scl, sda are high */
126 127
	setsda(adap, 0);
	udelay(adap->udelay);
L
Linus Torvalds 已提交
128 129 130
	scllo(adap);
}

131
static void i2c_repstart(struct i2c_algo_bit_data *adap)
L
Linus Torvalds 已提交
132
{
133 134
	/* assert: scl is low */
	sdahi(adap);
L
Linus Torvalds 已提交
135
	sclhi(adap);
136 137
	setsda(adap, 0);
	udelay(adap->udelay);
L
Linus Torvalds 已提交
138 139 140 141
	scllo(adap);
}


142
static void i2c_stop(struct i2c_algo_bit_data *adap)
L
Linus Torvalds 已提交
143 144 145
{
	/* assert: scl is low */
	sdalo(adap);
146
	sclhi(adap);
147 148
	setsda(adap, 1);
	udelay(adap->udelay);
L
Linus Torvalds 已提交
149 150 151 152
}



153
/* send a byte without start cond., look for arbitration,
L
Linus Torvalds 已提交
154 155 156 157 158 159
   check ackn. from slave */
/* returns:
 * 1 if the device acknowledged
 * 0 if the device did not ack
 * -ETIMEDOUT if an error occurred (while raising the scl line)
 */
J
Jean Delvare 已提交
160
static int i2c_outb(struct i2c_adapter *i2c_adap, unsigned char c)
L
Linus Torvalds 已提交
161 162 163 164 165 166 167
{
	int i;
	int sb;
	int ack;
	struct i2c_algo_bit_data *adap = i2c_adap->algo_data;

	/* assert: scl is low */
168
	for (i = 7; i >= 0; i--) {
J
Jean Delvare 已提交
169
		sb = (c >> i) & 1;
170
		setsda(adap, sb);
171
		udelay((adap->udelay + 1) / 2);
172
		if (sclhi(adap) < 0) { /* timed out */
J
Jean Delvare 已提交
173 174
			bit_dbg(1, &i2c_adap->dev, "i2c_outb: 0x%02x, "
				"timeout at bit #%d\n", (int)c, i);
L
Linus Torvalds 已提交
175
			return -ETIMEDOUT;
176 177 178 179 180 181
		}
		/* FIXME do arbitration here:
		 * if (sb && !getsda(adap)) -> ouch! Get out of here.
		 *
		 * Report a unique code, so higher level code can retry
		 * the whole (combined) message and *NOT* issue STOP.
L
Linus Torvalds 已提交
182
		 */
183
		scllo(adap);
L
Linus Torvalds 已提交
184 185
	}
	sdahi(adap);
186
	if (sclhi(adap) < 0) { /* timeout */
J
Jean Delvare 已提交
187 188 189
		bit_dbg(1, &i2c_adap->dev, "i2c_outb: 0x%02x, "
			"timeout at ack\n", (int)c);
		return -ETIMEDOUT;
190 191 192 193 194
	}

	/* read ack: SDA should be pulled down by slave, or it may
	 * NAK (usually to report problems with the data we wrote).
	 */
J
Jean Delvare 已提交
195 196 197
	ack = !getsda(adap);    /* ack: sda is pulled low -> success */
	bit_dbg(2, &i2c_adap->dev, "i2c_outb: 0x%02x %s\n", (int)c,
		ack ? "A" : "NA");
L
Linus Torvalds 已提交
198 199

	scllo(adap);
J
Jean Delvare 已提交
200
	return ack;
L
Linus Torvalds 已提交
201 202 203 204
	/* assert: scl is low (sda undef) */
}


205
static int i2c_inb(struct i2c_adapter *i2c_adap)
L
Linus Torvalds 已提交
206 207 208 209
{
	/* read byte via i2c port, without start/stop sequence	*/
	/* acknowledge is sent in i2c_read.			*/
	int i;
210
	unsigned char indata = 0;
L
Linus Torvalds 已提交
211 212 213 214
	struct i2c_algo_bit_data *adap = i2c_adap->algo_data;

	/* assert: scl is low */
	sdahi(adap);
215 216
	for (i = 0; i < 8; i++) {
		if (sclhi(adap) < 0) { /* timeout */
J
Jean Delvare 已提交
217 218
			bit_dbg(1, &i2c_adap->dev, "i2c_inb: timeout at bit "
				"#%d\n", 7 - i);
L
Linus Torvalds 已提交
219
			return -ETIMEDOUT;
220
		}
L
Linus Torvalds 已提交
221
		indata *= 2;
222
		if (getsda(adap))
L
Linus Torvalds 已提交
223
			indata |= 0x01;
224 225
		setscl(adap, 0);
		udelay(i == 7 ? adap->udelay / 2 : adap->udelay);
L
Linus Torvalds 已提交
226 227
	}
	/* assert: scl is low */
J
Jean Delvare 已提交
228
	return indata;
L
Linus Torvalds 已提交
229 230 231 232 233 234
}

/*
 * Sanity check for the adapter hardware - check the reaction of
 * the bus lines only if it seems to be idle.
 */
235 236 237
static int test_bus(struct i2c_algo_bit_data *adap, char *name)
{
	int scl, sda;
L
Linus Torvalds 已提交
238

239
	if (adap->getscl == NULL)
J
Jean Delvare 已提交
240
		pr_info("%s: Testing SDA only, SCL is not readable\n", name);
L
Linus Torvalds 已提交
241

242 243 244
	sda = getsda(adap);
	scl = (adap->getscl == NULL) ? 1 : getscl(adap);
	if (!scl || !sda) {
J
Jean Delvare 已提交
245
		printk(KERN_WARNING "%s: bus seems to be busy\n", name);
L
Linus Torvalds 已提交
246 247 248 249
		goto bailout;
	}

	sdalo(adap);
250 251 252
	sda = getsda(adap);
	scl = (adap->getscl == NULL) ? 1 : getscl(adap);
	if (sda) {
J
Jean Delvare 已提交
253
		printk(KERN_WARNING "%s: SDA stuck high!\n", name);
L
Linus Torvalds 已提交
254 255
		goto bailout;
	}
256
	if (!scl) {
J
Jean Delvare 已提交
257 258
		printk(KERN_WARNING "%s: SCL unexpected low "
		       "while pulling SDA low!\n", name);
L
Linus Torvalds 已提交
259
		goto bailout;
260
	}
L
Linus Torvalds 已提交
261 262

	sdahi(adap);
263 264 265
	sda = getsda(adap);
	scl = (adap->getscl == NULL) ? 1 : getscl(adap);
	if (!sda) {
J
Jean Delvare 已提交
266
		printk(KERN_WARNING "%s: SDA stuck low!\n", name);
L
Linus Torvalds 已提交
267 268
		goto bailout;
	}
269
	if (!scl) {
J
Jean Delvare 已提交
270 271
		printk(KERN_WARNING "%s: SCL unexpected low "
		       "while pulling SDA high!\n", name);
L
Linus Torvalds 已提交
272 273 274 275
		goto bailout;
	}

	scllo(adap);
276 277 278
	sda = getsda(adap);
	scl = (adap->getscl == NULL) ? 0 : getscl(adap);
	if (scl) {
J
Jean Delvare 已提交
279
		printk(KERN_WARNING "%s: SCL stuck high!\n", name);
L
Linus Torvalds 已提交
280 281
		goto bailout;
	}
282
	if (!sda) {
J
Jean Delvare 已提交
283 284
		printk(KERN_WARNING "%s: SDA unexpected low "
		       "while pulling SCL low!\n", name);
L
Linus Torvalds 已提交
285 286
		goto bailout;
	}
287

L
Linus Torvalds 已提交
288
	sclhi(adap);
289 290 291
	sda = getsda(adap);
	scl = (adap->getscl == NULL) ? 1 : getscl(adap);
	if (!scl) {
J
Jean Delvare 已提交
292
		printk(KERN_WARNING "%s: SCL stuck low!\n", name);
L
Linus Torvalds 已提交
293 294
		goto bailout;
	}
295
	if (!sda) {
J
Jean Delvare 已提交
296 297
		printk(KERN_WARNING "%s: SDA unexpected low "
		       "while pulling SCL high!\n", name);
L
Linus Torvalds 已提交
298 299
		goto bailout;
	}
J
Jean Delvare 已提交
300
	pr_info("%s: Test OK\n", name);
L
Linus Torvalds 已提交
301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317
	return 0;
bailout:
	sdahi(adap);
	sclhi(adap);
	return -ENODEV;
}

/* ----- Utility functions
 */

/* try_address tries to contact a chip for a number of
 * times before it gives up.
 * return values:
 * 1 chip answered
 * 0 chip did not answer
 * -x transmission error
 */
J
Jean Delvare 已提交
318
static int try_address(struct i2c_adapter *i2c_adap,
L
Linus Torvalds 已提交
319 320 321
		       unsigned char addr, int retries)
{
	struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
322
	int i, ret = 0;
323 324 325

	for (i = 0; i <= retries; i++) {
		ret = i2c_outb(i2c_adap, addr);
326 327
		if (ret == 1 || i == retries)
			break;
J
Jean Delvare 已提交
328
		bit_dbg(3, &i2c_adap->dev, "emitting stop condition\n");
L
Linus Torvalds 已提交
329 330
		i2c_stop(adap);
		udelay(adap->udelay);
331
		yield();
J
Jean Delvare 已提交
332
		bit_dbg(3, &i2c_adap->dev, "emitting start condition\n");
333
		i2c_start(adap);
L
Linus Torvalds 已提交
334
	}
J
Jean Delvare 已提交
335 336 337 338 339
	if (i && ret)
		bit_dbg(1, &i2c_adap->dev, "Used %d tries to %s client at "
			"0x%02x: %s\n", i + 1,
			addr & 1 ? "read from" : "write to", addr >> 1,
			ret == 1 ? "success" : "failed, timeout?");
L
Linus Torvalds 已提交
340 341 342 343 344
	return ret;
}

static int sendbytes(struct i2c_adapter *i2c_adap, struct i2c_msg *msg)
{
J
Jean Delvare 已提交
345
	const unsigned char *temp = msg->buf;
L
Linus Torvalds 已提交
346
	int count = msg->len;
347
	unsigned short nak_ok = msg->flags & I2C_M_IGNORE_NAK;
L
Linus Torvalds 已提交
348
	int retval;
349
	int wrcount = 0;
L
Linus Torvalds 已提交
350 351

	while (count > 0) {
J
Jean Delvare 已提交
352
		retval = i2c_outb(i2c_adap, *temp);
353 354 355 356

		/* OK/ACK; or ignored NAK */
		if ((retval > 0) || (nak_ok && (retval == 0))) {
			count--;
L
Linus Torvalds 已提交
357 358
			temp++;
			wrcount++;
359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378

		/* A slave NAKing the master means the slave didn't like
		 * something about the data it saw.  For example, maybe
		 * the SMBus PEC was wrong.
		 */
		} else if (retval == 0) {
			dev_err(&i2c_adap->dev, "sendbytes: NAK bailout.\n");
			return -EIO;

		/* Timeout; or (someday) lost arbitration
		 *
		 * FIXME Lost ARB implies retrying the transaction from
		 * the first message, after the "winning" master issues
		 * its STOP.  As a rule, upper layer code has no reason
		 * to know or care about this ... it is *NOT* an error.
		 */
		} else {
			dev_err(&i2c_adap->dev, "sendbytes: error %d\n",
					retval);
			return retval;
L
Linus Torvalds 已提交
379 380 381 382 383
		}
	}
	return wrcount;
}

384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399
static int acknak(struct i2c_adapter *i2c_adap, int is_ack)
{
	struct i2c_algo_bit_data *adap = i2c_adap->algo_data;

	/* assert: sda is high */
	if (is_ack)		/* send ack */
		setsda(adap, 0);
	udelay((adap->udelay + 1) / 2);
	if (sclhi(adap) < 0) {	/* timeout */
		dev_err(&i2c_adap->dev, "readbytes: ack/nak timeout\n");
		return -ETIMEDOUT;
	}
	scllo(adap);
	return 0;
}

J
Jean Delvare 已提交
400
static int readbytes(struct i2c_adapter *i2c_adap, struct i2c_msg *msg)
L
Linus Torvalds 已提交
401 402
{
	int inval;
403
	int rdcount = 0;	/* counts bytes read */
J
Jean Delvare 已提交
404
	unsigned char *temp = msg->buf;
L
Linus Torvalds 已提交
405
	int count = msg->len;
406
	const unsigned flags = msg->flags;
L
Linus Torvalds 已提交
407 408 409

	while (count > 0) {
		inval = i2c_inb(i2c_adap);
410
		if (inval >= 0) {
L
Linus Torvalds 已提交
411 412 413 414 415 416 417 418 419
			*temp = inval;
			rdcount++;
		} else {   /* read timed out */
			break;
		}

		temp++;
		count--;

420 421
		/* Some SMBus transactions require that we receive the
		   transaction length as the first read byte. */
422
		if (rdcount == 1 && (flags & I2C_M_RECV_LEN)) {
423
			if (inval <= 0 || inval > I2C_SMBUS_BLOCK_MAX) {
424 425
				if (!(flags & I2C_M_NO_RD_ACK))
					acknak(i2c_adap, 0);
J
Jean Delvare 已提交
426 427
				dev_err(&i2c_adap->dev, "readbytes: invalid "
					"block length (%d)\n", inval);
428 429 430 431 432 433 434 435
				return -EREMOTEIO;
			}
			/* The original count value accounts for the extra
			   bytes, that is, either 1 for a regular transaction,
			   or 2 for a PEC transaction. */
			count += inval;
			msg->len += inval;
		}
436 437 438 439 440 441 442 443 444 445 446 447

		bit_dbg(2, &i2c_adap->dev, "readbytes: 0x%02x %s\n",
			inval,
			(flags & I2C_M_NO_RD_ACK)
				? "(no ack/nak)"
				: (count ? "A" : "NA"));

		if (!(flags & I2C_M_NO_RD_ACK)) {
			inval = acknak(i2c_adap, count);
			if (inval < 0)
				return inval;
		}
L
Linus Torvalds 已提交
448 449 450 451 452 453 454 455 456 457
	}
	return rdcount;
}

/* doAddress initiates the transfer by generating the start condition (in
 * try_address) and transmits the address in the necessary format to handle
 * reads, writes as well as 10bit-addresses.
 * returns:
 *  0 everything went okay, the chip ack'ed, or IGNORE_NAK flag was set
 * -x an error occurred (like: -EREMOTEIO if the device did not answer, or
458
 *	-ETIMEDOUT, for example if the lines are stuck...)
L
Linus Torvalds 已提交
459
 */
J
Jean Delvare 已提交
460
static int bit_doAddress(struct i2c_adapter *i2c_adap, struct i2c_msg *msg)
L
Linus Torvalds 已提交
461 462 463 464 465 466 467 468 469
{
	unsigned short flags = msg->flags;
	unsigned short nak_ok = msg->flags & I2C_M_IGNORE_NAK;
	struct i2c_algo_bit_data *adap = i2c_adap->algo_data;

	unsigned char addr;
	int ret, retries;

	retries = nak_ok ? 0 : i2c_adap->retries;
470 471

	if (flags & I2C_M_TEN) {
L
Linus Torvalds 已提交
472
		/* a ten bit address */
473
		addr = 0xf0 | ((msg->addr >> 7) & 0x03);
J
Jean Delvare 已提交
474
		bit_dbg(2, &i2c_adap->dev, "addr0: %d\n", addr);
L
Linus Torvalds 已提交
475 476 477
		/* try extended address code...*/
		ret = try_address(i2c_adap, addr, retries);
		if ((ret != 1) && !nak_ok)  {
J
Jean Delvare 已提交
478 479
			dev_err(&i2c_adap->dev,
				"died at extended address code\n");
L
Linus Torvalds 已提交
480 481 482
			return -EREMOTEIO;
		}
		/* the remaining 8 bit address */
483
		ret = i2c_outb(i2c_adap, msg->addr & 0x7f);
L
Linus Torvalds 已提交
484 485
		if ((ret != 1) && !nak_ok) {
			/* the chip did not ack / xmission error occurred */
J
Jean Delvare 已提交
486
			dev_err(&i2c_adap->dev, "died at 2nd address code\n");
L
Linus Torvalds 已提交
487 488
			return -EREMOTEIO;
		}
489
		if (flags & I2C_M_RD) {
J
Jean Delvare 已提交
490 491
			bit_dbg(3, &i2c_adap->dev, "emitting repeated "
				"start condition\n");
L
Linus Torvalds 已提交
492 493 494 495
			i2c_repstart(adap);
			/* okay, now switch into reading mode */
			addr |= 0x01;
			ret = try_address(i2c_adap, addr, retries);
496
			if ((ret != 1) && !nak_ok) {
J
Jean Delvare 已提交
497 498
				dev_err(&i2c_adap->dev,
					"died at repeated address code\n");
L
Linus Torvalds 已提交
499 500 501 502
				return -EREMOTEIO;
			}
		}
	} else {		/* normal 7bit address	*/
503 504
		addr = msg->addr << 1;
		if (flags & I2C_M_RD)
L
Linus Torvalds 已提交
505
			addr |= 1;
506
		if (flags & I2C_M_REV_DIR_ADDR)
L
Linus Torvalds 已提交
507 508
			addr ^= 1;
		ret = try_address(i2c_adap, addr, retries);
509
		if ((ret != 1) && !nak_ok)
510
			return -ENXIO;
L
Linus Torvalds 已提交
511 512 513 514 515 516 517 518 519 520
	}

	return 0;
}

static int bit_xfer(struct i2c_adapter *i2c_adap,
		    struct i2c_msg msgs[], int num)
{
	struct i2c_msg *pmsg;
	struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
521
	int i, ret;
L
Linus Torvalds 已提交
522 523
	unsigned short nak_ok;

524 525 526 527 528 529
	if (adap->pre_xfer) {
		ret = adap->pre_xfer(i2c_adap);
		if (ret < 0)
			return ret;
	}

J
Jean Delvare 已提交
530
	bit_dbg(3, &i2c_adap->dev, "emitting start condition\n");
L
Linus Torvalds 已提交
531
	i2c_start(adap);
532
	for (i = 0; i < num; i++) {
L
Linus Torvalds 已提交
533
		pmsg = &msgs[i];
534
		nak_ok = pmsg->flags & I2C_M_IGNORE_NAK;
L
Linus Torvalds 已提交
535 536
		if (!(pmsg->flags & I2C_M_NOSTART)) {
			if (i) {
J
Jean Delvare 已提交
537 538
				bit_dbg(3, &i2c_adap->dev, "emitting "
					"repeated start condition\n");
L
Linus Torvalds 已提交
539 540 541 542
				i2c_repstart(adap);
			}
			ret = bit_doAddress(i2c_adap, pmsg);
			if ((ret != 0) && !nak_ok) {
J
Jean Delvare 已提交
543 544 545
				bit_dbg(1, &i2c_adap->dev, "NAK from "
					"device addr 0x%02x msg #%d\n",
					msgs[i].addr, i);
546
				goto bailout;
L
Linus Torvalds 已提交
547 548
			}
		}
549
		if (pmsg->flags & I2C_M_RD) {
L
Linus Torvalds 已提交
550 551
			/* read bytes into buffer*/
			ret = readbytes(i2c_adap, pmsg);
J
Jean Delvare 已提交
552 553 554
			if (ret >= 1)
				bit_dbg(2, &i2c_adap->dev, "read %d byte%s\n",
					ret, ret == 1 ? "" : "s");
555 556 557 558
			if (ret < pmsg->len) {
				if (ret >= 0)
					ret = -EREMOTEIO;
				goto bailout;
L
Linus Torvalds 已提交
559 560 561 562
			}
		} else {
			/* write bytes from buffer */
			ret = sendbytes(i2c_adap, pmsg);
J
Jean Delvare 已提交
563 564 565
			if (ret >= 1)
				bit_dbg(2, &i2c_adap->dev, "wrote %d byte%s\n",
					ret, ret == 1 ? "" : "s");
566 567 568 569
			if (ret < pmsg->len) {
				if (ret >= 0)
					ret = -EREMOTEIO;
				goto bailout;
L
Linus Torvalds 已提交
570 571 572
			}
		}
	}
573 574 575
	ret = i;

bailout:
J
Jean Delvare 已提交
576
	bit_dbg(3, &i2c_adap->dev, "emitting stop condition\n");
L
Linus Torvalds 已提交
577
	i2c_stop(adap);
578 579 580

	if (adap->post_xfer)
		adap->post_xfer(i2c_adap);
581
	return ret;
L
Linus Torvalds 已提交
582 583 584 585
}

static u32 bit_func(struct i2c_adapter *adap)
{
586
	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |
587 588
	       I2C_FUNC_SMBUS_READ_BLOCK_DATA |
	       I2C_FUNC_SMBUS_BLOCK_PROC_CALL |
L
Linus Torvalds 已提交
589 590 591 592 593 594
	       I2C_FUNC_10BIT_ADDR | I2C_FUNC_PROTOCOL_MANGLING;
}


/* -----exported algorithm data: -------------------------------------	*/

595
static const struct i2c_algorithm i2c_bit_algo = {
L
Linus Torvalds 已提交
596 597 598 599
	.master_xfer	= bit_xfer,
	.functionality	= bit_func,
};

600 601
/*
 * registering functions to load algorithms at runtime
L
Linus Torvalds 已提交
602
 */
603 604
static int __i2c_bit_add_bus(struct i2c_adapter *adap,
			     int (*add_adapter)(struct i2c_adapter *))
L
Linus Torvalds 已提交
605 606
{
	struct i2c_algo_bit_data *bit_adap = adap->algo_data;
607
	int ret;
L
Linus Torvalds 已提交
608 609

	if (bit_test) {
610
		ret = test_bus(bit_adap, adap->name);
611
		if (ret < 0)
L
Linus Torvalds 已提交
612 613 614 615 616
			return -ENODEV;
	}

	/* register new adapter to i2c module... */
	adap->algo = &i2c_bit_algo;
617
	adap->retries = 3;
L
Linus Torvalds 已提交
618

619 620 621 622 623 624 625 626 627 628
	ret = add_adapter(adap);
	if (ret < 0)
		return ret;

	/* Complain if SCL can't be read */
	if (bit_adap->getscl == NULL) {
		dev_warn(&adap->dev, "Not I2C compliant: can't read SCL\n");
		dev_warn(&adap->dev, "Bus may be unreliable\n");
	}
	return 0;
629 630 631 632
}

int i2c_bit_add_bus(struct i2c_adapter *adap)
{
633
	return __i2c_bit_add_bus(adap, i2c_add_adapter);
L
Linus Torvalds 已提交
634 635 636
}
EXPORT_SYMBOL(i2c_bit_add_bus);

637 638
int i2c_bit_add_numbered_bus(struct i2c_adapter *adap)
{
639
	return __i2c_bit_add_bus(adap, i2c_add_numbered_adapter);
640 641 642
}
EXPORT_SYMBOL(i2c_bit_add_numbered_bus);

L
Linus Torvalds 已提交
643 644 645
MODULE_AUTHOR("Simon G. Vogl <simon@tk.uni-linz.ac.at>");
MODULE_DESCRIPTION("I2C-Bus bit-banging algorithm");
MODULE_LICENSE("GPL");