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Diffstat (limited to 'drivers/i2c/algos/i2c-algo-bit.c')
-rw-r--r--drivers/i2c/algos/i2c-algo-bit.c573
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 00000000000..fb5b732238e
--- /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");
generated by cgit v1.2.3-18-g5258 (git 2.32.0) at 2024-11-23 00:08:55 +0000