Orange Pi5 kernel

// SPDX-License-Identifier: GPL-2.0+
/*
 * i2c-algo-bit.c: i2c driver algorithms for bit-shift adapters
 *
 *   Copyright (C) 1995-2000 Simon G. Vogl
 *
 * With some changes from Frodo Looijaard <frodol@dds.nl>, Kyösti Mälkki
 * <kmalkki@cc.hut.fi> and Jean Delvare <jdelvare@suse.de>
 */
 
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/delay.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, int, S_IRUGO);
MODULE_PARM_DESC(bit_test, "lines testing - 0 off; 1 report; 2 fail if 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)) {
<------><------><------>/* Test one last time, as we may have been preempted
<------><------><------> * between last check and timeout test.
<------><------><------> */
<------><------><------>if (getscl(adap))
<------><------><------><------>break;
<------><------><------>return -ETIMEDOUT;
<------><------>}
<------><------>cpu_relax();
<------>}
#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_adapter *i2c_adap)
{
<------>struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
<------>const char *name = i2c_adap->name;
<------>int scl, sda, ret;
 
<------>if (adap->pre_xfer) {
<------><------>ret = adap->pre_xfer(i2c_adap);
<------><------>if (ret < 0)
<------><------><------>return -ENODEV;
<------>}
 
<------>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 (scl=%d, sda=%d)\n",
<------><------>       name, scl, sda);
<------><------>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;
<------>}
 
<------>if (adap->post_xfer)
<------><------>adap->post_xfer(i2c_adap);
 
<------>pr_info("%s: Test OK\n", name);
<------>return 0;
bailout:
<------>sdahi(adap);
<------>sclhi(adap);
 
<------>if (adap->post_xfer)
<------><------>adap->post_xfer(i2c_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 -EPROTO;
<------><------><------>}
<------><------><------>/* 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: -ENXIO 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) & 0x06);
<------><------>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 -ENXIO;
<------><------>}
<------><------>/* the remaining 8 bit address */
<------><------>ret = i2c_outb(i2c_adap, msg->addr & 0xff);
<------><------>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 -ENXIO;
<------><------>}
<------><------>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 -EIO;
<------><------><------>}
<------><------>}
<------>} else {		/* normal 7bit address	*/
<------><------>addr = i2c_8bit_addr_from_msg(msg);
<------><------>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) {
<------><------><------><------>if (msgs[i - 1].flags & I2C_M_STOP) {
<------><------><------><------><------>bit_dbg(3, &i2c_adap->dev,
<------><------><------><------><------><------>"emitting enforced stop/start condition\n");
<------><------><------><------><------>i2c_stop(adap);
<------><------><------><------><------>i2c_start(adap);
<------><------><------><------>} else {
<------><------><------><------><------>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 = -EIO;
<------><------><------><------>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 = -EIO;
<------><------><------><------>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;
}
 
/*
 * We print a warning when we are not flagged to support atomic transfers but
 * will try anyhow. That's what the I2C core would do as well. Sadly, we can't
 * modify the algorithm struct at probe time because this struct is exported
 * 'const'.
 */
static int bit_xfer_atomic(struct i2c_adapter *i2c_adap, struct i2c_msg msgs[],
<------><------><------>   int num)
{
<------>struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
 
<------>if (!adap->can_do_atomic)
<------><------>dev_warn(&i2c_adap->dev, "not flagged for atomic transfers\n");
 
<------>return bit_xfer(i2c_adap, msgs, num);
}
 
static u32 bit_func(struct i2c_adapter *adap)
{
<------>return I2C_FUNC_I2C | I2C_FUNC_NOSTART | 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: -------------------------------------	*/
 
const struct i2c_algorithm i2c_bit_algo = {
<------>.master_xfer = bit_xfer,
<------>.master_xfer_atomic = bit_xfer_atomic,
<------>.functionality = bit_func,
};
EXPORT_SYMBOL(i2c_bit_algo);
 
static const struct i2c_adapter_quirks i2c_bit_quirk_no_clk_stretch = {
<------>.flags = I2C_AQ_NO_CLK_STRETCH,
};
 
/*
 * registering functions to load algorithms at runtime
 */
static int __i2c_bit_add_bus(struct i2c_adapter *adap,
<------><------><------>     int (*add_adapter)(struct i2c_adapter *))
{
<------>struct i2c_algo_bit_data *bit_adap = adap->algo_data;
<------>int ret;
 
<------>if (bit_test) {
<------><------>ret = test_bus(adap);
<------><------>if (bit_test >= 2 && ret < 0)
<------><------><------>return -ENODEV;
<------>}
 
<------>/* register new adapter to i2c module... */
<------>adap->algo = &i2c_bit_algo;
<------>adap->retries = 3;
<------>if (bit_adap->getscl == NULL)
<------><------>adap->quirks = &i2c_bit_quirk_no_clk_stretch;
 
<------>/*
<------> * We tried forcing SCL/SDA to an initial state here. But that caused a
<------> * regression, sadly. Check Bugzilla #200045 for details.
<------> */
 
<------>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;
}
 
int i2c_bit_add_bus(struct i2c_adapter *adap)
{
<------>return __i2c_bit_add_bus(adap, i2c_add_adapter);
}
EXPORT_SYMBOL(i2c_bit_add_bus);
 
int i2c_bit_add_numbered_bus(struct i2c_adapter *adap)
{
<------>return __i2c_bit_add_bus(adap, i2c_add_numbered_adapter);
}
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");