diff options
Diffstat (limited to 'drivers/i2c/algos/i2c-algo-bit.c')
| -rw-r--r-- | drivers/i2c/algos/i2c-algo-bit.c | 573 |
1 files changed, 573 insertions, 0 deletions
diff --git a/drivers/i2c/algos/i2c-algo-bit.c b/drivers/i2c/algos/i2c-algo-bit.c new file mode 100644 index 0000000..fb5b732 --- /dev/null +++ b/drivers/i2c/algos/i2c-algo-bit.c @@ -0,0 +1,573 @@ +/* ------------------------------------------------------------------------- */ +/* 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>, Kyösti Mälkki + <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/slab.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 ----------------------------------------------- */ +#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 */ + + +/* ----- global variables --------------------------------------------- */ + +/* module parameters: + */ +static int i2c_debug; +static int bit_test; /* see if the line-setting functions work */ + +/* --- 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); +} + +/* + * Raise scl line, and do checking for delays. This is necessary for slower + * devices. + */ +static inline int sclhi(struct i2c_algo_bit_data *adap) +{ + unsigned long start; + + setscl(adap,1); + + /* Not all adapters have scl sense line... */ + if (adap->getscl == NULL ) { + udelay(adap->udelay); + return 0; + } + + 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)) { + return -ETIMEDOUT; + } + cond_resched(); + } + DEBSTAT(printk(KERN_DEBUG "needed %ld jiffies\n", jiffies-start)); + udelay(adap->udelay); + 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); + sclhi(adap); + 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 */ + for ( i=7 ; i>=0 ; i-- ) { + sb = c & ( 1 << i ); + setsda(adap,sb); + udelay(adap->udelay); + DEBPROTO(printk(KERN_DEBUG "%d",sb!=0)); + if (sclhi(adap)<0) { /* timed out */ + sdahi(adap); /* we don't want to block the net */ + DEB2(printk(KERN_DEBUG " i2c_outb: 0x%02x, timeout at bit #%d\n", c&0xff, i)); + 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 */ + DEB2(printk(KERN_DEBUG " i2c_outb: 0x%02x, timeout at ack\n", c&0xff)); + return -ETIMEDOUT; + }; + /* read ack: SDA should be pulled down by slave */ + ack=getsda(adap); /* ack: sda is pulled low ->success. */ + DEB2(printk(KERN_DEBUG " i2c_outb: 0x%02x , getsda() = %d\n", c & 0xff, ack)); + + DEBPROTO( printk(KERN_DEBUG "[%2.2x]",c&0xff) ); + DEBPROTO(if (0==ack){ printk(KERN_DEBUG " A ");} else printk(KERN_DEBUG " 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 */ + sdahi(adap); + for (i=0;i<8;i++) { + if (sclhi(adap)<0) { /* timeout */ + DEB2(printk(KERN_DEBUG " i2c_inb: timeout at bit #%d\n", 7-i)); + return -ETIMEDOUT; + }; + indata *= 2; + if ( getsda(adap) ) + indata |= 0x01; + scllo(adap); + } + /* assert: scl is low */ + DEB2(printk(KERN_DEBUG "i2c_inb: 0x%02x\n", indata & 0xff)); + + DEBPROTO(printk(KERN_DEBUG " 0x%02x", 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; + + if (adap->getscl==NULL) + printk(KERN_INFO "i2c-algo-bit.o: Testing SDA only, " + "SCL is not readable.\n"); + + sda=getsda(adap); + scl=(adap->getscl==NULL?1:getscl(adap)); + printk(KERN_DEBUG "i2c-algo-bit.o: (0) scl=%d, sda=%d\n",scl,sda); + if (!scl || !sda ) { + printk(KERN_WARNING "i2c-algo-bit.o: %s seems to be busy.\n", name); + goto bailout; + } + + sdalo(adap); + sda=getsda(adap); + scl=(adap->getscl==NULL?1:getscl(adap)); + printk(KERN_DEBUG "i2c-algo-bit.o: (1) scl=%d, sda=%d\n",scl,sda); + if ( 0 != sda ) { + printk(KERN_WARNING "i2c-algo-bit.o: SDA stuck high!\n"); + goto bailout; + } + if ( 0 == scl ) { + printk(KERN_WARNING "i2c-algo-bit.o: SCL unexpected low " + "while pulling SDA low!\n"); + goto bailout; + } + + sdahi(adap); + sda=getsda(adap); + scl=(adap->getscl==NULL?1:getscl(adap)); + printk(KERN_DEBUG "i2c-algo-bit.o: (2) scl=%d, sda=%d\n",scl,sda); + if ( 0 == sda ) { + printk(KERN_WARNING "i2c-algo-bit.o: SDA stuck low!\n"); + goto bailout; + } + if ( 0 == scl ) { + printk(KERN_WARNING "i2c-algo-bit.o: SCL unexpected low " + "while pulling SDA high!\n"); + goto bailout; + } + + scllo(adap); + sda=getsda(adap); + scl=(adap->getscl==NULL?0:getscl(adap)); + printk(KERN_DEBUG "i2c-algo-bit.o: (3) scl=%d, sda=%d\n",scl,sda); + if ( 0 != scl ) { + printk(KERN_WARNING "i2c-algo-bit.o: SCL stuck high!\n"); + goto bailout; + } + if ( 0 == sda ) { + printk(KERN_WARNING "i2c-algo-bit.o: SDA unexpected low " + "while pulling SCL low!\n"); + goto bailout; + } + + sclhi(adap); + sda=getsda(adap); + scl=(adap->getscl==NULL?1:getscl(adap)); + printk(KERN_DEBUG "i2c-algo-bit.o: (4) scl=%d, sda=%d\n",scl,sda); + if ( 0 == scl ) { + printk(KERN_WARNING "i2c-algo-bit.o: SCL stuck low!\n"); + goto bailout; + } + if ( 0 == sda ) { + printk(KERN_WARNING "i2c-algo-bit.o: SDA unexpected low " + "while pulling SCL high!\n"); + goto bailout; + } + printk(KERN_INFO "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(KERN_DEBUG "i2c-algo-bit.o: Used %d tries to %s client at 0x%02x : %s\n", + i+1, addr & 1 ? "read" : "write", addr>>1, + ret==1 ? "success" : ret==0 ? "no ack" : "failed, timeout?" ) + ); + return ret; +} + +static int sendbytes(struct i2c_adapter *i2c_adap, struct i2c_msg *msg) +{ + struct i2c_algo_bit_data *adap = i2c_adap->algo_data; + char c; + const 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) { + c = *temp; + DEB2(dev_dbg(&i2c_adap->dev, "sendbytes: writing %2.2X\n", c&0xff)); + retval = i2c_outb(i2c_adap,c); + if ((retval>0) || (nak_ok && (retval==0))) { /* ok or ignored NAK */ + count--; + temp++; + wrcount++; + } else { /* arbitration or no acknowledge */ + dev_err(&i2c_adap->dev, "sendbytes: error - bailout.\n"); + 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, struct i2c_msg *msg) +{ + int inval; + int rdcount=0; /* counts bytes read */ + struct i2c_algo_bit_data *adap = i2c_adap->algo_data; + char *temp = msg->buf; + int count = msg->len; + + 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(KERN_ERR "i2c-algo-bit.o: readbytes: i2c_inb timed out.\n"); + break; + } + + temp++; + count--; + + if (msg->flags & I2C_M_NO_RD_ACK) + continue; + + if ( count > 0 ) { /* 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(KERN_ERR "i2c-algo-bit.o: readbytes: Timeout at ack\n"); + return -ETIMEDOUT; + }; + scllo(adap); + sdahi(adap); + } + 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 inline 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); + DEB2(printk(KERN_DEBUG "addr0: %d\n",addr)); + /* try extended address code...*/ + ret = try_address(i2c_adap, addr, retries); + if ((ret != 1) && !nak_ok) { + printk(KERN_ERR "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 */ + printk(KERN_ERR "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) && !nak_ok) { + printk(KERN_ERR "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) && !nak_ok) + 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; + unsigned short nak_ok; + + 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) { + i2c_repstart(adap); + } + ret = bit_doAddress(i2c_adap, pmsg); + if ((ret != 0) && !nak_ok) { + DEB2(printk(KERN_DEBUG "i2c-algo-bit.o: NAK from device addr %2.2x 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); + DEB2(printk(KERN_DEBUG "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); + DEB2(printk(KERN_DEBUG "i2c-algo-bit.o: wrote %d bytes.\n",ret)); + if (ret < pmsg->len ) { + return (ret<0) ? ret : -EREMOTEIO; + } + } + } + i2c_stop(adap); + return num; +} + +static u32 bit_func(struct i2c_adapter *adap) +{ + return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | + I2C_FUNC_10BIT_ADDR | I2C_FUNC_PROTOCOL_MANGLING; +} + + +/* -----exported algorithm data: ------------------------------------- */ + +static struct i2c_algorithm i2c_bit_algo = { + .name = "Bit-shift algorithm", + .id = I2C_ALGO_BIT, + .master_xfer = bit_xfer, + .functionality = bit_func, +}; + +/* + * registering functions to load algorithms at runtime + */ +int i2c_bit_add_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; + } + + DEB2(dev_dbg(&adap->dev, "hw routines registered.\n")); + + /* 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 */ + + i2c_add_adapter(adap); + return 0; +} + + +int i2c_bit_del_bus(struct i2c_adapter *adap) +{ + return i2c_del_adapter(adap); +} + +EXPORT_SYMBOL(i2c_bit_add_bus); +EXPORT_SYMBOL(i2c_bit_del_bus); + +MODULE_AUTHOR("Simon G. Vogl <simon@tk.uni-linz.ac.at>"); +MODULE_DESCRIPTION("I2C-Bus bit-banging algorithm"); +MODULE_LICENSE("GPL"); + +module_param(bit_test, bool, 0); +module_param(i2c_debug, int, S_IRUGO | S_IWUSR); + +MODULE_PARM_DESC(bit_test, "Test the lines of the bus to see if it is stuck"); +MODULE_PARM_DESC(i2c_debug, + "debug level - 0 off; 1 normal; 2,3 more verbose; 9 bit-protocol"); |
