Attachment 45636 Details for Bug 36221 – i2c-algo-bit.c from SuSE rpm; ??

[patch] i2c-algo-bit.c from SuSE rpm; ??

back_i2c-algo-bit.c (text/plain), 15.97 KB, created by revealed on 2011-04-14 15:27:06 UTC

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Creator: revealed

Created: 2011-04-14 15:27:06 UTC

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obsolete

>/* -------------------------------------------------------------------------
> * i2c-algo-bit.c i2c driver algorithms for bit-shift adapters
> * -------------------------------------------------------------------------
> *   Copyright (C) 1995-2000 Simon G. Vogl
>
>    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
>    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
> * ------------------------------------------------------------------------- */
>
>/* With some changes from Frodo Looijaard <frodol@dds.nl>, KyÃ¶sti MÃ¤lkki
>   <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 ----------------------------------------------- */
>
>#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 */
>
>/* ----- global variables ---------------------------------------------	*/
>
>static int bit_test;	/* see if the line-setting functions work	*/
>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
>
>/* --- setting states on the bus with the right timing: ---------------	*/
>
>#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)
>
>static inline void sdalo(struct i2c_algo_bit_data *adap)
>{
>	setsda(adap, 0);
>	udelay((adap->udelay + 1) / 2);
>}
>
>static inline void sdahi(struct i2c_algo_bit_data *adap)
>{
>	setsda(adap, 1);
>	udelay((adap->udelay + 1) / 2);
>}
>
>static inline void scllo(struct i2c_algo_bit_data *adap)
>{
>	setscl(adap, 0);
>	udelay(adap->udelay / 2);
>}
>
>/*
> * Raise scl line, and do checking for delays. This is necessary for slower
> * devices.
> */
>static int sclhi(struct i2c_algo_bit_data *adap)
>{
>	unsigned long start;
>
>	setscl(adap, 1);
>
>	/* Not all adapters have scl sense line... */
>	if (!adap->getscl)
>		goto done;
>
>	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.
>		 */
>		if (time_after(jiffies, start + adap->timeout))
>			return -ETIMEDOUT;
>		cond_resched();
>	}
>#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
>
>done:
>	udelay(adap->udelay);
>	return 0;
>}
>
>
>/* --- other auxiliary functions --------------------------------------	*/
>static void i2c_start(struct i2c_algo_bit_data *adap)
>{
>	/* assert: scl, sda are high */
>	setsda(adap, 0);
>	udelay(adap->udelay);
>	scllo(adap);
>}
>
>static void i2c_repstart(struct i2c_algo_bit_data *adap)
>{
>	/* assert: scl is low */
>	sdahi(adap);
>	sclhi(adap);
>	setsda(adap, 0);
>	udelay(adap->udelay);
>	scllo(adap);
>}
>
>
>static void i2c_stop(struct i2c_algo_bit_data *adap)
>{
>	/* assert: scl is low */
>	sdalo(adap);
>	sclhi(adap);
>	setsda(adap, 1);
>	udelay(adap->udelay);
>}
>
>
>
>/* send a byte without start cond., look for arbitration,
>   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)
> */
>static int i2c_outb(struct i2c_adapter *i2c_adap, unsigned char c)
>{
>	int i;
>	int sb;
>	int ack;
>	struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
>
>	/* assert: scl is low */
>	for (i = 7; i >= 0; i--) {
>		sb = (c >> i) & 1;
>		setsda(adap, sb);
>		udelay((adap->udelay + 1) / 2);
>		if (sclhi(adap) < 0) { /* timed out */
>			bit_dbg(1, &i2c_adap->dev, "i2c_outb: 0x%02x, "
>				"timeout at bit #%d\n", (int)c, i);
>			return -ETIMEDOUT;
>		}
>		/* 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.
>		 */
>		scllo(adap);
>	}
>	sdahi(adap);
>	if (sclhi(adap) < 0) { /* timeout */
>		bit_dbg(1, &i2c_adap->dev, "i2c_outb: 0x%02x, "
>			"timeout at ack\n", (int)c);
>		return -ETIMEDOUT;
>	}
>
>	/* read ack: SDA should be pulled down by slave, or it may
>	 * NAK (usually to report problems with the data we wrote).
>	 */
>	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");
>
>	scllo(adap);
>	return ack;
>	/* assert: scl is low (sda undef) */
>}
>
>
>static int i2c_inb(struct i2c_adapter *i2c_adap)
>{
>	/* read byte via i2c port, without start/stop sequence	*/
>	/* acknowledge is sent in i2c_read.			*/
>	int i;
>	unsigned char indata = 0;
>	struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
>
>	/* assert: scl is low */
>	sdahi(adap);
>	for (i = 0; i < 8; i++) {
>		if (sclhi(adap) < 0) { /* timeout */
>			bit_dbg(1, &i2c_adap->dev, "i2c_inb: timeout at bit "
>				"#%d\n", 7 - i);
>			return -ETIMEDOUT;
>		}
>		indata *= 2;
>		if (getsda(adap))
>			indata |= 0x01;
>		setscl(adap, 0);
>		udelay(i == 7 ? adap->udelay / 2 : adap->udelay);
>	}
>	/* assert: scl is low */
>	return indata;
>}
>
>/*
> * Sanity check for the adapter hardware - check the reaction of
> * the bus lines only if it seems to be idle.
> */
>static int test_bus(struct i2c_algo_bit_data *adap, char *name)
>{
>	int scl, sda;
>
>	if (adap->getscl == NULL)
>		pr_info("%s: Testing SDA only, SCL is not readable\n", name);
>
>	sda = getsda(adap);
>	scl = (adap->getscl == NULL) ? 1 : getscl(adap);
>	if (!scl || !sda) {
>		printk(KERN_WARNING "%s: bus seems to be busy\n", name);
>		goto bailout;
>	}
>
>	sdalo(adap);
>	sda = getsda(adap);
>	scl = (adap->getscl == NULL) ? 1 : getscl(adap);
>	if (sda) {
>		printk(KERN_WARNING "%s: SDA stuck high!\n", name);
>		goto bailout;
>	}
>	if (!scl) {
>		printk(KERN_WARNING "%s: SCL unexpected low "
>		       "while pulling SDA low!\n", name);
>		goto bailout;
>	}
>
>	sdahi(adap);
>	sda = getsda(adap);
>	scl = (adap->getscl == NULL) ? 1 : getscl(adap);
>	if (!sda) {
>		printk(KERN_WARNING "%s: SDA stuck low!\n", name);
>		goto bailout;
>	}
>	if (!scl) {
>		printk(KERN_WARNING "%s: SCL unexpected low "
>		       "while pulling SDA high!\n", name);
>		goto bailout;
>	}
>
>	scllo(adap);
>	sda = getsda(adap);
>	scl = (adap->getscl == NULL) ? 0 : getscl(adap);
>	if (scl) {
>		printk(KERN_WARNING "%s: SCL stuck high!\n", name);
>		goto bailout;
>	}
>	if (!sda) {
>		printk(KERN_WARNING "%s: SDA unexpected low "
>		       "while pulling SCL low!\n", name);
>		goto bailout;
>	}
>
>	sclhi(adap);
>	sda = getsda(adap);
>	scl = (adap->getscl == NULL) ? 1 : getscl(adap);
>	if (!scl) {
>		printk(KERN_WARNING "%s: SCL stuck low!\n", name);
>		goto bailout;
>	}
>	if (!sda) {
>		printk(KERN_WARNING "%s: SDA unexpected low "
>		       "while pulling SCL high!\n", name);
>		goto bailout;
>	}
>	pr_info("%s: Test OK\n", name);
>	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
> */
>static int try_address(struct i2c_adapter *i2c_adap,
>		       unsigned char addr, int retries)
>{
>	struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
>	int i, ret = 0;
>
>	for (i = 0; i <= retries; i++) {
>		ret = i2c_outb(i2c_adap, addr);
>		if (ret == 1 || i == retries)
>			break;
>		bit_dbg(3, &i2c_adap->dev, "emitting stop condition\n");
>		i2c_stop(adap);
>		udelay(adap->udelay);
>		yield();
>		bit_dbg(3, &i2c_adap->dev, "emitting start condition\n");
>		i2c_start(adap);
>	}
>	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?");
>	return ret;
>}
>
>static int sendbytes(struct i2c_adapter *i2c_adap, struct i2c_msg *msg)
>{
>	const unsigned char *temp = msg->buf;
>	int count = msg->len;
>	unsigned short nak_ok = msg->flags & I2C_M_IGNORE_NAK;
>	int retval;
>	int wrcount = 0;
>
>	while (count > 0) {
>		retval = i2c_outb(i2c_adap, *temp);
>
>		/* OK/ACK; or ignored NAK */
>		if ((retval > 0) || (nak_ok && (retval == 0))) {
>			count--;
>			temp++;
>			wrcount++;
>
>		/* 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;
>		}
>	}
>	return wrcount;
>}
>
>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;
>}
>
>static int readbytes(struct i2c_adapter *i2c_adap, struct i2c_msg *msg)
>{
>	int inval;
>	int rdcount = 0;	/* counts bytes read */
>	unsigned char *temp = msg->buf;
>	int count = msg->len;
>	const unsigned flags = msg->flags;
>
>	while (count > 0) {
>		inval = i2c_inb(i2c_adap);
>		if (inval >= 0) {
>			*temp = inval;
>			rdcount++;
>		} else {   /* read timed out */
>			break;
>		}
>
>		temp++;
>		count--;
>
>		/* Some SMBus transactions require that we receive the
>		   transaction length as the first read byte. */
>		if (rdcount == 1 && (flags & I2C_M_RECV_LEN)) {
>			if (inval <= 0 || inval > I2C_SMBUS_BLOCK_MAX) {
>				if (!(flags & I2C_M_NO_RD_ACK))
>					acknak(i2c_adap, 0);
>				dev_err(&i2c_adap->dev, "readbytes: invalid "
>					"block length (%d)\n", inval);
>				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;
>		}
>
>		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;
>		}
>	}
>	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
> *	-ETIMEDOUT, for example if the lines are stuck...)
> */
>static int bit_doAddress(struct i2c_adapter *i2c_adap, struct i2c_msg *msg)
>{
>	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;
>
>	if (flags & I2C_M_TEN) {
>		/* a ten bit address */
>		addr = 0xf0 | ((msg->addr >> 7) & 0x03);
>		bit_dbg(2, &i2c_adap->dev, "addr0: %d\n", addr);
>		/* try extended address code...*/
>		ret = try_address(i2c_adap, addr, retries);
>		if ((ret != 1) && !nak_ok)  {
>			dev_err(&i2c_adap->dev,
>				"died at extended address code\n");
>			return -EREMOTEIO;
>		}
>		/* the remaining 8 bit address */
>		ret = i2c_outb(i2c_adap, msg->addr & 0x7f);
>		if ((ret != 1) && !nak_ok) {
>			/* the chip did not ack / xmission error occurred */
>			dev_err(&i2c_adap->dev, "died at 2nd address code\n");
>			return -EREMOTEIO;
>		}
>		if (flags & I2C_M_RD) {
>			bit_dbg(3, &i2c_adap->dev, "emitting repeated "
>				"start condition\n");
>			i2c_repstart(adap);
>			/* okay, now switch into reading mode */
>			addr |= 0x01;
>			ret = try_address(i2c_adap, addr, retries);
>			if ((ret != 1) && !nak_ok) {
>				dev_err(&i2c_adap->dev,
>					"died at repeated address code\n");
>				return -EREMOTEIO;
>			}
>		}
>	} else {		/* normal 7bit address	*/
>		addr = msg->addr << 1;
>		if (flags & I2C_M_RD)
>			addr |= 1;
>		if (flags & I2C_M_REV_DIR_ADDR)
>			addr ^= 1;
>		ret = try_address(i2c_adap, addr, retries);
>		if ((ret != 1) && !nak_ok)
>			return -ENXIO;
>	}
>
>	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;
>	int i, ret;
>	unsigned short nak_ok;
>
>	if (adap->pre_xfer) {
>		ret = adap->pre_xfer(i2c_adap);
>		if (ret < 0)
>			return ret;
>	}
>
>	bit_dbg(3, &i2c_adap->dev, "emitting start condition\n");
>	i2c_start(adap);
>	for (i = 0; i < num; i++) {
>		pmsg = &msgs[i];
>		nak_ok = pmsg->flags & I2C_M_IGNORE_NAK;
>		if (!(pmsg->flags & I2C_M_NOSTART)) {
>			if (i) {
>				bit_dbg(3, &i2c_adap->dev, "emitting "
>					"repeated start condition\n");
>				i2c_repstart(adap);
>			}
>			ret = bit_doAddress(i2c_adap, pmsg);
>			if ((ret != 0) && !nak_ok) {
>				bit_dbg(1, &i2c_adap->dev, "NAK from "
>					"device addr 0x%02x msg #%d\n",
>					msgs[i].addr, i);
>				goto bailout;
>			}
>		}
>		if (pmsg->flags & I2C_M_RD) {
>			/* read bytes into buffer*/
>			ret = readbytes(i2c_adap, pmsg);
>			if (ret >= 1)
>				bit_dbg(2, &i2c_adap->dev, "read %d byte%s\n",
>					ret, ret == 1 ? "" : "s");
>			if (ret < pmsg->len) {
>				if (ret >= 0)
>					ret = -EREMOTEIO;
>				goto bailout;
>			}
>		} else {
>			/* write bytes from buffer */
>			ret = sendbytes(i2c_adap, pmsg);
>			if (ret >= 1)
>				bit_dbg(2, &i2c_adap->dev, "wrote %d byte%s\n",
>					ret, ret == 1 ? "" : "s");
>			if (ret < pmsg->len) {
>				if (ret >= 0)
>					ret = -EREMOTEIO;
>				goto bailout;
>			}
>		}
>	}
>	ret = i;
>
>bailout:
>	bit_dbg(3, &i2c_adap->dev, "emitting stop condition\n");
>	i2c_stop(adap);
>
>	if (adap->post_xfer)
>		adap->post_xfer(i2c_adap);
>	return ret;
>}
>
>static u32 bit_func(struct i2c_adapter *adap)
>{
>	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |
>	       I2C_FUNC_SMBUS_READ_BLOCK_DATA |
>	       I2C_FUNC_SMBUS_BLOCK_PROC_CALL |
>	       I2C_FUNC_10BIT_ADDR | I2C_FUNC_PROTOCOL_MANGLING;
>}
>
>
>/* -----exported algorithm data: -------------------------------------	*/
>
>static const struct i2c_algorithm i2c_bit_algo = {
>	.master_xfer	= bit_xfer,
>	.functionality	= bit_func,
>};
>
>/*
> * registering functions to load algorithms at runtime
> */
>static int i2c_bit_prepare_bus(struct i2c_adapter *adap)
>{
>	struct i2c_algo_bit_data *bit_adap = adap->algo_data;
>
>	if (bit_test) {
>		int ret = test_bus(bit_adap, adap->name);
>		if (ret < 0)
>			return -ENODEV;
>	}
>
>	/* register new adapter to i2c module... */
>	adap->algo = &i2c_bit_algo;
>	adap->retries = 3;
>
>	return 0;
>}
>
>int i2c_bit_add_bus(struct i2c_adapter *adap)
>{
>	int err;
>
>	err = i2c_bit_prepare_bus(adap);
>	if (err)
>		return err;
>
>	return i2c_add_adapter(adap);
>}
>EXPORT_SYMBOL(i2c_bit_add_bus);
>
>int i2c_bit_add_numbered_bus(struct i2c_adapter *adap)
>{
>	int err;
>
>	err = i2c_bit_prepare_bus(adap);
>	if (err)
>		return err;
>
>	return i2c_add_numbered_adapter(adap);
>}
>EXPORT_SYMBOL(i2c_bit_add_numbered_bus);
>
>MODULE_AUTHOR("Simon G. Vogl <simon@tk.uni-linz.ac.at>");
>MODULE_DESCRIPTION("I2C-Bus bit-banging algorithm");
>MODULE_LICENSE("GPL");

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Attachments on bug 36221: 45589 | 45590 | 45615 | 45619 | 45633 | 45636 | 45637

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