patch-2.3.34 linux/drivers/i2c/i2c-algo-bit.c

• Lines: 659
• Date: Thu Dec 16 13:59:38 1999
• Orig file: v2.3.33/linux/drivers/i2c/i2c-algo-bit.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.3.33/linux/drivers/i2c/i2c-algo-bit.c linux/drivers/i2c/i2c-algo-bit.c
@@ -0,0 +1,658 @@
+/* ------------------------------------------------------------------------- */
+/* i2c-algo-bit.c i2c driver algorithms for bit-shift adapters		     */
+/* ------------------------------------------------------------------------- */
+/*   Copyright (C) 1995-99 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 <kmalkki@cc.hut.fi> and even
+   Frodo Looijaard <frodol@dds.nl> */
+
+
+/*
+static char alg_rcsid[] = "$Id: i2c-algo-bit.c,v 1.20 1999/11/12 11:26:20 frodo Exp $";
+*/
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/delay.h>
+#include <linux/malloc.h>
+#include <linux/version.h>
+#if LINUX_VERSION_CODE >= 0x020135
+#include <linux/init.h>
+#else
+#define __init 
+#endif
+
+#if LINUX_VERSION_CODE >= 0x020100
+#  include <asm/uaccess.h>
+#else
+#  include <asm/segment.h>
+#endif
+
+/* 2.0.0 kernel compatibility */
+#if LINUX_VERSION_CODE < 0x020100
+#define MODULE_AUTHOR(noone)
+#define MODULE_DESCRIPTION(none)
+#define MODULE_PARM(no,param)
+#define MODULE_PARM_DESC(no,description)
+#define EXPORT_SYMBOL(noexport)
+#define EXPORT_NO_SYMBOLS
+#endif
+
+#include <linux/ioport.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 */
+
+/* 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	*/
+/*
+#if LINUX_VERSION_CODE >= 0x02016e
+#define SLO_IO      jif=jiffies;while(jiffies<=jif+i2c_table[minor].veryslow)\
+                        if (need_resched) schedule();
+#else
+#define SLO_IO      jif=jiffies;while(jiffies<=jif+i2c_table[minor].veryslow)\
+			if (need_resched) schedule();
+#endif
+*/
+
+
+/* ----- global variables ---------------------------------------------	*/
+
+#ifdef SLO_IO
+	int jif;
+#endif
+
+/* module parameters:
+ */
+static int i2c_debug=0;
+static int bit_test=0;	/* see if the line-setting functions work	*/
+static int bit_scan=0;	/* 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 LINUX_VERSION_CODE >= 0x02016e
+		if (current->need_resched)
+			schedule();
+#else
+		if (need_resched)
+			schedule();
+#endif
+	}
+	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 occured (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 occured (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 occured */
+			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;
+		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;i<num;i++) {
+		pmsg = &msgs[i];
+		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;
+			}
+		}
+		if (i<num-1) {
+			i2c_repstart(adap);
+		}
+	}
+	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;
+}
+
+
+/* -----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)
+{
+
+	i2c_del_adapter(adap);
+
+	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 <simon@tk.uni-linz.ac.at>");
+MODULE_DESCRIPTION("I2C-Bus bit-banging algorithm");
+
+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