diff options
Diffstat (limited to 'drivers/i2c/algos/i2c-algo-bit.c')
| -rw-r--r-- | drivers/i2c/algos/i2c-algo-bit.c | 322 |
1 files changed, 188 insertions, 134 deletions
diff --git a/drivers/i2c/algos/i2c-algo-bit.c b/drivers/i2c/algos/i2c-algo-bit.c index a37cb6b8593..65ef9664d5d 100644 --- a/drivers/i2c/algos/i2c-algo-bit.c +++ b/drivers/i2c/algos/i2c-algo-bit.c @@ -1,7 +1,7 @@ -/* ------------------------------------------------------------------------- */ -/* i2c-algo-bit.c i2c driver algorithms for bit-shift adapters */ -/* ------------------------------------------------------------------------- */ -/* Copyright (C) 1995-2000 Simon G. Vogl +/* ------------------------------------------------------------------------- + * 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 @@ -15,17 +15,16 @@ 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. */ -/* ------------------------------------------------------------------------- */ + Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, + MA 02110-1301 USA. + * ------------------------------------------------------------------------- */ /* With some changes from Frodo Looijaard <frodol@dds.nl>, Kyösti Mälkki - <kmalkki@cc.hut.fi> and Jean Delvare <khali@linux-fr.org> */ + <kmalkki@cc.hut.fi> and Jean Delvare <jdelvare@suse.de> */ #include <linux/kernel.h> #include <linux/module.h> #include <linux/delay.h> -#include <linux/slab.h> -#include <linux/init.h> #include <linux/errno.h> #include <linux/sched.h> #include <linux/i2c.h> @@ -48,8 +47,8 @@ /* ----- 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"); +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; @@ -60,26 +59,26 @@ MODULE_PARM_DESC(i2c_debug, /* --- 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) +#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); + setsda(adap, 0); udelay((adap->udelay + 1) / 2); } static inline void sdahi(struct i2c_algo_bit_data *adap) { - setsda(adap,1); + setsda(adap, 1); udelay((adap->udelay + 1) / 2); } static inline void scllo(struct i2c_algo_bit_data *adap) { - setscl(adap,0); + setscl(adap, 0); udelay(adap->udelay / 2); } @@ -91,23 +90,28 @@ static int sclhi(struct i2c_algo_bit_data *adap) { unsigned long start; - setscl(adap,1); + setscl(adap, 1); /* Not all adapters have scl sense line... */ if (!adap->getscl) goto done; - start=jiffies; - while (! getscl(adap) ) { - /* the 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 - * while they are processing data internally. - */ - if (time_after_eq(jiffies, start+adap->timeout)) { + 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; } - cond_resched(); + cpu_relax(); } #ifdef DEBUG if (jiffies != start && i2c_debug >= 3) @@ -118,11 +122,11 @@ static int sclhi(struct i2c_algo_bit_data *adap) done: udelay(adap->udelay); return 0; -} +} /* --- other auxiliary functions -------------------------------------- */ -static void i2c_start(struct i2c_algo_bit_data *adap) +static void i2c_start(struct i2c_algo_bit_data *adap) { /* assert: scl, sda are high */ setsda(adap, 0); @@ -130,7 +134,7 @@ static void i2c_start(struct i2c_algo_bit_data *adap) scllo(adap); } -static void i2c_repstart(struct i2c_algo_bit_data *adap) +static void i2c_repstart(struct i2c_algo_bit_data *adap) { /* assert: scl is low */ sdahi(adap); @@ -141,18 +145,18 @@ static void i2c_repstart(struct i2c_algo_bit_data *adap) } -static void i2c_stop(struct i2c_algo_bit_data *adap) +static void i2c_stop(struct i2c_algo_bit_data *adap) { /* assert: scl is low */ sdalo(adap); - sclhi(adap); + sclhi(adap); setsda(adap, 1); udelay(adap->udelay); } -/* send a byte without start cond., look for arbitration, +/* send a byte without start cond., look for arbitration, check ackn. from slave */ /* returns: * 1 if the device acknowledged @@ -167,27 +171,33 @@ static int i2c_outb(struct i2c_adapter *i2c_adap, unsigned char c) struct i2c_algo_bit_data *adap = i2c_adap->algo_data; /* assert: scl is low */ - for ( i=7 ; i>=0 ; i-- ) { + for (i = 7; i >= 0; i--) { sb = (c >> i) & 1; - setsda(adap,sb); + setsda(adap, sb); udelay((adap->udelay + 1) / 2); - if (sclhi(adap)<0) { /* timed out */ + 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; - }; - /* do arbitration here: - * if ( sb && ! getsda(adap) ) -> ouch! Get out of here. + } + /* 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 */ + 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 */ + } + + /* 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"); @@ -198,24 +208,24 @@ static int i2c_outb(struct i2c_adapter *i2c_adap, unsigned char c) } -static int i2c_inb(struct i2c_adapter *i2c_adap) +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; + 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 */ + 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) ) + if (getsda(adap)) indata |= 0x01; setscl(adap, 0); udelay(i == 7 ? adap->udelay / 2 : adap->udelay); @@ -228,75 +238,94 @@ static int i2c_inb(struct i2c_adapter *i2c_adap) * 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; +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->getscl==NULL) + 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\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 ( 0 != sda ) { + sda = getsda(adap); + scl = (adap->getscl == NULL) ? 1 : getscl(adap); + if (sda) { printk(KERN_WARNING "%s: SDA stuck high!\n", name); goto bailout; } - if ( 0 == scl ) { + 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 ( 0 == sda ) { + sda = getsda(adap); + scl = (adap->getscl == NULL) ? 1 : getscl(adap); + if (!sda) { printk(KERN_WARNING "%s: SDA stuck low!\n", name); goto bailout; } - if ( 0 == scl ) { + 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 ( 0 != scl ) { + sda = getsda(adap); + scl = (adap->getscl == NULL) ? 0 : getscl(adap); + if (scl) { printk(KERN_WARNING "%s: SCL stuck high!\n", name); goto bailout; } - if ( 0 == sda ) { + 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 ( 0 == scl ) { + sda = getsda(adap); + scl = (adap->getscl == NULL) ? 1 : getscl(adap); + if (!scl) { printk(KERN_WARNING "%s: SCL stuck low!\n", name); goto bailout; } - if ( 0 == sda ) { + 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; } @@ -314,9 +343,10 @@ 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 = -1; - for (i=0;i<=retries;i++) { - ret = i2c_outb(i2c_adap,addr); + 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"); @@ -338,20 +368,38 @@ 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; + unsigned short nak_ok = msg->flags & I2C_M_IGNORE_NAK; int retval; - int wrcount=0; + int wrcount = 0; while (count > 0) { retval = i2c_outb(i2c_adap, *temp); - if ((retval>0) || (nak_ok && (retval==0))) { /* ok or ignored NAK */ - count--; + + /* OK/ACK; or ignored NAK */ + if ((retval > 0) || (nak_ok && (retval == 0))) { + count--; temp++; wrcount++; - } else { /* arbitration or no acknowledge */ - dev_err(&i2c_adap->dev, "sendbytes: error - bailout.\n"); - return (retval<0)? retval : -EFAULT; - /* got a better one ?? */ + + /* 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; @@ -376,14 +424,14 @@ static int acknak(struct i2c_adapter *i2c_adap, int is_ack) static int readbytes(struct i2c_adapter *i2c_adap, struct i2c_msg *msg) { int inval; - int rdcount=0; /* counts bytes read */ + 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) { + if (inval >= 0) { *temp = inval; rdcount++; } else { /* read timed out */ @@ -401,7 +449,7 @@ static int readbytes(struct i2c_adapter *i2c_adap, struct i2c_msg *msg) acknak(i2c_adap, 0); dev_err(&i2c_adap->dev, "readbytes: invalid " "block length (%d)\n", inval); - return -EREMOTEIO; + return -EPROTO; } /* The original count value accounts for the extra bytes, that is, either 1 for a regular transaction, @@ -430,8 +478,8 @@ static int readbytes(struct i2c_adapter *i2c_adap, struct i2c_msg *msg) * 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...) + * -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) { @@ -443,47 +491,47 @@ static int bit_doAddress(struct i2c_adapter *i2c_adap, struct i2c_msg *msg) int ret, retries; retries = nak_ok ? 0 : i2c_adap->retries; - - if ( (flags & I2C_M_TEN) ) { + + if (flags & I2C_M_TEN) { /* a ten bit address */ - addr = 0xf0 | (( msg->addr >> 7) & 0x03); + 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 -EREMOTEIO; + return -ENXIO; } /* the remaining 8 bit address */ - ret = i2c_outb(i2c_adap,msg->addr & 0x7f); + 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 -EREMOTEIO; + return -ENXIO; } - if ( flags & I2C_M_RD ) { + 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) { + if ((ret != 1) && !nak_ok) { dev_err(&i2c_adap->dev, "died at repeated address code\n"); - return -EREMOTEIO; + return -EIO; } } } else { /* normal 7bit address */ - addr = ( msg->addr << 1 ); - if (flags & I2C_M_RD ) + addr = msg->addr << 1; + if (flags & I2C_M_RD) addr |= 1; - if (flags & I2C_M_REV_DIR_ADDR ) + if (flags & I2C_M_REV_DIR_ADDR) addr ^= 1; ret = try_address(i2c_adap, addr, retries); - if ((ret!=1) && !nak_ok) - return -EREMOTEIO; + if ((ret != 1) && !nak_ok) + return -ENXIO; } return 0; @@ -494,15 +542,20 @@ static int bit_xfer(struct i2c_adapter *i2c_adap, { struct i2c_msg *pmsg; struct i2c_algo_bit_data *adap = i2c_adap->algo_data; - - int i,ret; + 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++) { + for (i = 0; i < num; i++) { pmsg = &msgs[i]; - nak_ok = pmsg->flags & I2C_M_IGNORE_NAK; + nak_ok = pmsg->flags & I2C_M_IGNORE_NAK; if (!(pmsg->flags & I2C_M_NOSTART)) { if (i) { bit_dbg(3, &i2c_adap->dev, "emitting " @@ -517,7 +570,7 @@ static int bit_xfer(struct i2c_adapter *i2c_adap, goto bailout; } } - if (pmsg->flags & I2C_M_RD ) { + if (pmsg->flags & I2C_M_RD) { /* read bytes into buffer*/ ret = readbytes(i2c_adap, pmsg); if (ret >= 1) @@ -525,7 +578,7 @@ static int bit_xfer(struct i2c_adapter *i2c_adap, ret, ret == 1 ? "" : "s"); if (ret < pmsg->len) { if (ret >= 0) - ret = -EREMOTEIO; + ret = -EIO; goto bailout; } } else { @@ -536,7 +589,7 @@ static int bit_xfer(struct i2c_adapter *i2c_adap, ret, ret == 1 ? "" : "s"); if (ret < pmsg->len) { if (ret >= 0) - ret = -EREMOTEIO; + ret = -EIO; goto bailout; } } @@ -546,12 +599,15 @@ static int bit_xfer(struct i2c_adapter *i2c_adap, 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 | + 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; @@ -560,54 +616,52 @@ static u32 bit_func(struct i2c_adapter *adap) /* -----exported algorithm data: ------------------------------------- */ -static const struct i2c_algorithm i2c_bit_algo = { +const struct i2c_algorithm i2c_bit_algo = { .master_xfer = bit_xfer, .functionality = bit_func, }; +EXPORT_SYMBOL(i2c_bit_algo); -/* - * registering functions to load algorithms at runtime +/* + * registering functions to load algorithms at runtime */ -static int i2c_bit_prepare_bus(struct i2c_adapter *adap) +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) { - int ret = test_bus(bit_adap, adap->name); - if (ret<0) + 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; - adap->timeout = 100; /* default values, should */ - adap->retries = 3; /* be replaced by defines */ + 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) { - int err; - - err = i2c_bit_prepare_bus(adap); - if (err) - return err; - - return i2c_add_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) { - int err; - - err = i2c_bit_prepare_bus(adap); - if (err) - return err; - - return i2c_add_numbered_adapter(adap); + return __i2c_bit_add_bus(adap, i2c_add_numbered_adapter); } EXPORT_SYMBOL(i2c_bit_add_numbered_bus); |