/* ------------------------------------------------------------------------- */ /* 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 Kyösti Mälkki and even Frodo Looijaard */ /* $Id: i2c-algo-bit.c,v 1.30 2001/07/29 02:44:25 mds Exp $ */ #include #include #include #include #include #include #include #include #include #include #include #include /* ----- global defines ----------------------------------------------- */ #define DEB(x) if (i2c_debug>=1) x; #define DEB2(x) if (i2c_debug>=2) x; #define DEBSTAT(x) if (i2c_debug>=3) x; /* print several statistical values*/ #define DEBPROTO(x) if (i2c_debug>=9) { x; } /* debug the protocol by showing transferred bits */ /* debugging - slow down transfer to have a look at the data .. */ /* I use this with two leds&resistors, each one connected to sda,scl */ /* respectively. This makes sure that the algorithm works. Some chips */ /* might not like this, as they have an internal timeout of some mils */ /* #define SLO_IO jif=jiffies;while(jiffies<=jif+i2c_table[minor].veryslow)\ if (need_resched) schedule(); */ /* ----- global variables --------------------------------------------- */ #ifdef SLO_IO int jif; #endif /* module parameters: */ static int i2c_debug; static int bit_test; /* see if the line-setting functions work */ static int bit_scan; /* have a look at what's hanging 'round */ /* --- 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); } static inline void sdahi(struct i2c_algo_bit_data *adap) { setsda(adap,1); udelay(adap->udelay); } static inline void scllo(struct i2c_algo_bit_data *adap) { setscl(adap,0); udelay(adap->udelay); #ifdef SLO_IO SLO_IO #endif } /* * Raise scl line, and do checking for delays. This is necessary for slower * devices. */ static inline int sclhi(struct i2c_algo_bit_data *adap) { int start=jiffies; setscl(adap,1); udelay(adap->udelay); /* Not all adapters have scl sense line... */ if (adap->getscl == NULL ) return 0; 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. */ setscl(adap,1); if (start+adap->timeout <= jiffies) { return -ETIMEDOUT; } if (current->need_resched) schedule(); } DEBSTAT(printk("needed %ld jiffies\n", jiffies-start)); #ifdef SLO_IO SLO_IO #endif return 0; } /* --- other auxiliary functions -------------------------------------- */ static void i2c_start(struct i2c_algo_bit_data *adap) { /* assert: scl, sda are high */ DEBPROTO(printk("S ")); sdalo(adap); scllo(adap); } static void i2c_repstart(struct i2c_algo_bit_data *adap) { /* scl, sda may not be high */ DEBPROTO(printk(" Sr ")); setsda(adap,1); setscl(adap,1); udelay(adap->udelay); sdalo(adap); scllo(adap); } static void i2c_stop(struct i2c_algo_bit_data *adap) { DEBPROTO(printk("P\n")); /* assert: scl is low */ sdalo(adap); sclhi(adap); sdahi(adap); } /* 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, char c) { int i; int sb; int ack; struct i2c_algo_bit_data *adap = i2c_adap->algo_data; /* assert: scl is low */ DEB2(printk(" i2c_outb:%2.2X\n",c&0xff)); for ( i=7 ; i>=0 ; i-- ) { sb = c & ( 1 << i ); setsda(adap,sb); udelay(adap->udelay); DEBPROTO(printk("%d",sb!=0)); if (sclhi(adap)<0) { /* timed out */ sdahi(adap); /* we don't want to block the net */ return -ETIMEDOUT; }; /* do arbitration here: * if ( sb && ! getsda(adap) ) -> ouch! Get out of here. */ setscl(adap, 0 ); udelay(adap->udelay); } sdahi(adap); if (sclhi(adap)<0){ /* timeout */ return -ETIMEDOUT; }; /* read ack: SDA should be pulled down by slave */ ack=getsda(adap); /* ack: sda is pulled low ->success. */ DEB2(printk(" i2c_outb: getsda() = 0x%2.2x\n", ~ack )); DEBPROTO( printk("[%2.2x]",c&0xff) ); DEBPROTO(if (0==ack){ printk(" A ");} else printk(" NA ") ); scllo(adap); return 0==ack; /* return 1 if device acked */ /* 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 */ DEB2(printk("i2c_inb.\n")); sdahi(adap); for (i=0;i<8;i++) { if (sclhi(adap)<0) { /* timeout */ return -ETIMEDOUT; }; indata *= 2; if ( getsda(adap) ) indata |= 0x01; scllo(adap); } /* assert: scl is low */ DEBPROTO(printk(" %2.2x", indata & 0xff)); return (int) (indata & 0xff); } /* * 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; sda=getsda(adap); if (adap->getscl==NULL) { printk("i2c-algo-bit.o: Warning: Adapter can't read from clock line - skipping test.\n"); return 0; } scl=getscl(adap); printk("i2c-algo-bit.o: Adapter: %s scl: %d sda: %d -- testing...\n", name,getscl(adap),getsda(adap)); if (!scl || !sda ) { printk("i2c-algo-bit.o: %s seems to be busy.\n",name); goto bailout; } sdalo(adap); printk("i2c-algo-bit.o:1 scl: %d sda: %d \n",getscl(adap), getsda(adap)); if ( 0 != getsda(adap) ) { printk("i2c-algo-bit.o: %s SDA stuck high!\n",name); sdahi(adap); goto bailout; } if ( 0 == getscl(adap) ) { printk("i2c-algo-bit.o: %s SCL unexpected low while pulling SDA low!\n", name); goto bailout; } sdahi(adap); printk("i2c-algo-bit.o:2 scl: %d sda: %d \n",getscl(adap), getsda(adap)); if ( 0 == getsda(adap) ) { printk("i2c-algo-bit.o: %s SDA stuck low!\n",name); sdahi(adap); goto bailout; } if ( 0 == getscl(adap) ) { printk("i2c-algo-bit.o: %s SCL unexpected low while SDA high!\n", name); goto bailout; } scllo(adap); printk("i2c-algo-bit.o:3 scl: %d sda: %d \n",getscl(adap), getsda(adap)); if ( 0 != getscl(adap) ) { printk("i2c-algo-bit.o: %s SCL stuck high!\n",name); sclhi(adap); goto bailout; } if ( 0 == getsda(adap) ) { printk("i2c-algo-bit.o: %s SDA unexpected low while pulling SCL low!\n", name); goto bailout; } sclhi(adap); printk("i2c-algo-bit.o:4 scl: %d sda: %d \n",getscl(adap), getsda(adap)); if ( 0 == getscl(adap) ) { printk("i2c-algo-bit.o: %s SCL stuck low!\n",name); sclhi(adap); goto bailout; } if ( 0 == getsda(adap) ) { printk("i2c-algo-bit.o: %s SDA unexpected low while SCL high!\n", name); goto bailout; } printk("i2c-algo-bit.o: %s passed test.\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 inline 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); if (ret==1) break; /* success! */ i2c_stop(adap); udelay(5/*adap->udelay*/); if (i==retries) /* no success */ break; i2c_start(adap); udelay(adap->udelay); } DEB2(if (i) printk("i2c-algo-bit.o: needed %d retries for %d\n", i,addr)); return ret; } static int sendbytes(struct i2c_adapter *i2c_adap,const char *buf, int count) { struct i2c_algo_bit_data *adap = i2c_adap->algo_data; char c; const char *temp = buf; int retval; int wrcount=0; while (count > 0) { c = *temp; DEB2(printk("i2c-algo-bit.o: %s i2c_write: writing %2.2X\n", i2c_adap->name, c&0xff)); retval = i2c_outb(i2c_adap,c); if (retval>0) { count--; temp++; wrcount++; } else { /* arbitration or no acknowledge */ printk("i2c-algo-bit.o: %s i2c_write: error - bailout.\n", i2c_adap->name); i2c_stop(adap); return (retval<0)? retval : -EFAULT; /* got a better one ?? */ } #if 0 /* from asm/delay.h */ __delay(adap->mdelay * (loops_per_sec / 1000) ); #endif } return wrcount; } static inline int readbytes(struct i2c_adapter *i2c_adap,char *buf,int count) { char *temp = buf; int inval; int rdcount=0; /* counts bytes read */ struct i2c_algo_bit_data *adap = i2c_adap->algo_data; while (count > 0) { inval = i2c_inb(i2c_adap); /*printk("%#02x ",inval); if ( ! (count % 16) ) printk("\n"); */ if (inval>=0) { *temp = inval; rdcount++; } else { /* read timed out */ printk("i2c-algo-bit.o: i2c_read: i2c_inb timed out.\n"); break; } if ( count > 1 ) { /* send ack */ sdalo(adap); DEBPROTO(printk(" Am ")); } else { sdahi(adap); /* neg. ack on last byte */ DEBPROTO(printk(" NAm ")); } if (sclhi(adap)<0) { /* timeout */ sdahi(adap); printk("i2c-algo-bit.o: i2c_read: Timeout at ack\n"); return -ETIMEDOUT; }; scllo(adap); sdahi(adap); temp++; count--; } 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 * -x an error occurred (like: -EREMOTEIO if the device did not answer, or * -ETIMEDOUT, for example if the lines are stuck...) */ static inline int bit_doAddress(struct i2c_adapter *i2c_adap, struct i2c_msg *msg, int retries) { unsigned short flags = msg->flags; struct i2c_algo_bit_data *adap = i2c_adap->algo_data; unsigned char addr; int ret; if ( (flags & I2C_M_TEN) ) { /* a ten bit address */ addr = 0xf0 | (( msg->addr >> 7) & 0x03); DEB2(printk("addr0: %d\n",addr)); /* try extended address code...*/ ret = try_address(i2c_adap, addr, retries); if (ret!=1) { printk("died at extended address code.\n"); return -EREMOTEIO; } /* the remaining 8 bit address */ ret = i2c_outb(i2c_adap,msg->addr & 0x7f); if (ret != 1) { /* the chip did not ack / xmission error occurred */ printk("died at 2nd address code.\n"); return -EREMOTEIO; } if ( flags & I2C_M_RD ) { i2c_repstart(adap); /* okay, now switch into reading mode */ addr |= 0x01; ret = try_address(i2c_adap, addr, retries); if (ret!=1) { printk("died at extended 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) { return -EREMOTEIO; } } 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; i2c_start(adap); for (i=0;iflags & I2C_M_NOSTART)) { if (i) { i2c_repstart(adap); } ret = bit_doAddress(i2c_adap,pmsg,i2c_adap->retries); if (ret != 0) { DEB2(printk("i2c-algo-bit.o: NAK from device adr %#2x msg #%d\n" ,msgs[i].addr,i)); return (ret<0) ? ret : -EREMOTEIO; } } if (pmsg->flags & I2C_M_RD ) { /* read bytes into buffer*/ ret = readbytes(i2c_adap,pmsg->buf,pmsg->len); DEB2(printk("i2c-algo-bit.o: read %d bytes.\n",ret)); if (ret < pmsg->len ) { return (ret<0)? ret : -EREMOTEIO; } } else { /* write bytes from buffer */ ret = sendbytes(i2c_adap,pmsg->buf,pmsg->len); DEB2(printk("i2c-algo-bit.o: wrote %d bytes.\n",ret)); if (ret < pmsg->len ) { return (ret<0) ? ret : -EREMOTEIO; } } } i2c_stop(adap); return num; } static int algo_control(struct i2c_adapter *adapter, unsigned int cmd, unsigned long arg) { return 0; } static u32 bit_func(struct i2c_adapter *adap) { return I2C_FUNC_SMBUS_EMUL | I2C_FUNC_10BIT_ADDR | I2C_FUNC_PROTOCOL_MANGLING; } /* -----exported algorithm data: ------------------------------------- */ static struct i2c_algorithm i2c_bit_algo = { "Bit-shift algorithm", I2C_ALGO_BIT, bit_xfer, NULL, NULL, /* slave_xmit */ NULL, /* slave_recv */ algo_control, /* ioctl */ bit_func, /* functionality */ }; /* * registering functions to load algorithms at runtime */ int i2c_bit_add_bus(struct i2c_adapter *adap) { int i; 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; } DEB2(printk("i2c-algo-bit.o: hw routines for %s registered.\n", adap->name)); /* register new adapter to i2c module... */ adap->id |= i2c_bit_algo.id; adap->algo = &i2c_bit_algo; adap->timeout = 100; /* default values, should */ adap->retries = 3; /* be replaced by defines */ /* scan bus */ if (bit_scan) { int ack; printk(KERN_INFO " i2c-algo-bit.o: scanning bus %s.\n", adap->name); for (i = 0x00; i < 0xff; i+=2) { i2c_start(bit_adap); ack = i2c_outb(adap,i); i2c_stop(bit_adap); if (ack>0) { printk("(%02x)",i>>1); } else printk("."); } printk("\n"); } #ifdef MODULE MOD_INC_USE_COUNT; #endif i2c_add_adapter(adap); return 0; } int i2c_bit_del_bus(struct i2c_adapter *adap) { int res; if ((res = i2c_del_adapter(adap)) < 0) return res; DEB2(printk("i2c-algo-bit.o: adapter unregistered: %s\n",adap->name)); #ifdef MODULE MOD_DEC_USE_COUNT; #endif return 0; } int __init i2c_algo_bit_init (void) { printk("i2c-algo-bit.o: i2c bit algorithm module\n"); return 0; } EXPORT_SYMBOL(i2c_bit_add_bus); EXPORT_SYMBOL(i2c_bit_del_bus); #ifdef MODULE MODULE_AUTHOR("Simon G. Vogl "); MODULE_DESCRIPTION("I2C-Bus bit-banging algorithm"); MODULE_LICENSE("GPL"); MODULE_PARM(bit_test, "i"); MODULE_PARM(bit_scan, "i"); MODULE_PARM(i2c_debug,"i"); MODULE_PARM_DESC(bit_test, "Test the lines of the bus to see if it is stuck"); MODULE_PARM_DESC(bit_scan, "Scan for active chips on the bus"); MODULE_PARM_DESC(i2c_debug, "debug level - 0 off; 1 normal; 2,3 more verbose; 9 bit-protocol"); int init_module(void) { return i2c_algo_bit_init(); } void cleanup_module(void) { } #endif