| 0,0 → 1,615 |
|---|
| /* ------------------------------------------------------------------------- |
| * 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 <types.h> |
| #include <list.h> |
| #include <syscall.h> |
| #include <errno.h> |
| #include <linux/i2c.h> |
| #include <linux/i2c-algo-bit.h> |
| |
| |
| /* ----- global defines ----------------------------------------------- */ |
| |
| #ifdef DEBUG |
| #define bit_dbg(level, dev, format, args...) \ |
| do { \ |
| if (i2c_debug >= level) \ |
| dev_dbg(dev, format, ##args); \ |
| } while (0) |
| #else |
| #define bit_dbg(level, dev, format, args...) \ |
| do {} while (0) |
| #endif /* DEBUG */ |
| |
| |
| /* ----- global variables --------------------------------------------- */ |
| |
| 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 + 1) / 2); |
| } |
| |
| static inline void sdahi(struct i2c_algo_bit_data *adap) |
| { |
| setsda(adap, 1); |
| udelay((adap->udelay + 1) / 2); |
| } |
| |
| static inline void scllo(struct i2c_algo_bit_data *adap) |
| { |
| setscl(adap, 0); |
| udelay(adap->udelay / 2); |
| } |
| |
| /* |
| * Raise scl line, and do checking for delays. This is necessary for slower |
| * devices. |
| */ |
| static int sclhi(struct i2c_algo_bit_data *adap) |
| { |
| unsigned long start; |
| |
| setscl(adap, 1); |
| |
| /* Not all adapters have scl sense line... */ |
| if (!adap->getscl) |
| goto done; |
| |
| // 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)) |
| // return -ETIMEDOUT; |
| |
| udelay(adap->udelay); |
| |
| // cond_resched(); |
| } |
| #ifdef DEBUG |
| if (jiffies != start && i2c_debug >= 3) |
| pr_debug("i2c-algo-bit: needed %ld jiffies for SCL to go " |
| "high\n", jiffies - start); |
| #endif |
| |
| done: |
| udelay(adap->udelay); |
| return 0; |
| } |
| |
| |
| /* --- other auxiliary functions -------------------------------------- */ |
| static void i2c_start(struct i2c_algo_bit_data *adap) |
| { |
| /* assert: scl, sda are high */ |
| setsda(adap, 0); |
| udelay(adap->udelay); |
| scllo(adap); |
| } |
| |
| static void i2c_repstart(struct i2c_algo_bit_data *adap) |
| { |
| /* assert: scl is low */ |
| sdahi(adap); |
| sclhi(adap); |
| setsda(adap, 0); |
| udelay(adap->udelay); |
| scllo(adap); |
| } |
| |
| |
| static void i2c_stop(struct i2c_algo_bit_data *adap) |
| { |
| /* assert: scl is low */ |
| sdalo(adap); |
| sclhi(adap); |
| setsda(adap, 1); |
| udelay(adap->udelay); |
| } |
| |
| |
| |
| /* 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, unsigned 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 >> i) & 1; |
| setsda(adap, sb); |
| udelay((adap->udelay + 1) / 2); |
| 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; |
| } |
| /* 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 */ |
| // 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, 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"); |
| |
| scllo(adap); |
| return ack; |
| /* 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 */ |
| bit_dbg(1, &i2c_adap->dev, "i2c_inb: timeout at bit " |
| "#%d\n", 7 - i); |
| return -ETIMEDOUT; |
| } |
| indata *= 2; |
| if (getsda(adap)) |
| indata |= 0x01; |
| setscl(adap, 0); |
| udelay(i == 7 ? adap->udelay / 2 : adap->udelay); |
| } |
| /* assert: scl is low */ |
| return indata; |
| } |
| |
| /* |
| * 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) |
| 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); |
| goto bailout; |
| } |
| |
| sdalo(adap); |
| sda = getsda(adap); |
| scl = (adap->getscl == NULL) ? 1 : getscl(adap); |
| if (sda) { |
| printk(KERN_WARNING "%s: SDA stuck high!\n", name); |
| goto bailout; |
| } |
| 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 (!sda) { |
| printk(KERN_WARNING "%s: SDA stuck low!\n", name); |
| goto bailout; |
| } |
| 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 (scl) { |
| printk(KERN_WARNING "%s: SCL stuck high!\n", name); |
| goto bailout; |
| } |
| 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 (!scl) { |
| printk(KERN_WARNING "%s: SCL stuck low!\n", name); |
| goto bailout; |
| } |
| if (!sda) { |
| printk(KERN_WARNING "%s: SDA unexpected low " |
| "while pulling SCL high!\n", name); |
| goto bailout; |
| } |
| pr_info("%s: Test OK\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 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 = 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"); |
| i2c_stop(adap); |
| udelay(adap->udelay); |
| // yield(); |
| bit_dbg(3, &i2c_adap->dev, "emitting start condition\n"); |
| i2c_start(adap); |
| } |
| if (i && ret) |
| bit_dbg(1, &i2c_adap->dev, "Used %d tries to %s client at " |
| "0x%02x: %s\n", i + 1, |
| addr & 1 ? "read from" : "write to", addr >> 1, |
| ret == 1 ? "success" : "failed, timeout?"); |
| return ret; |
| } |
| |
| 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; |
| int retval; |
| int wrcount = 0; |
| |
| while (count > 0) { |
| retval = i2c_outb(i2c_adap, *temp); |
| |
| /* OK/ACK; or ignored NAK */ |
| if ((retval > 0) || (nak_ok && (retval == 0))) { |
| count--; |
| temp++; |
| wrcount++; |
| |
| /* 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; |
| } |
| |
| static int acknak(struct i2c_adapter *i2c_adap, int is_ack) |
| { |
| struct i2c_algo_bit_data *adap = i2c_adap->algo_data; |
| |
| /* assert: sda is high */ |
| if (is_ack) /* send ack */ |
| setsda(adap, 0); |
| udelay((adap->udelay + 1) / 2); |
| if (sclhi(adap) < 0) { /* timeout */ |
| // dev_err(&i2c_adap->dev, "readbytes: ack/nak timeout\n"); |
| // return -ETIMEDOUT; |
| } |
| scllo(adap); |
| return 0; |
| } |
| |
| static int readbytes(struct i2c_adapter *i2c_adap, struct i2c_msg *msg) |
| { |
| int inval; |
| 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) { |
| *temp = inval; |
| rdcount++; |
| } else { /* read timed out */ |
| break; |
| } |
| |
| temp++; |
| count--; |
| |
| /* Some SMBus transactions require that we receive the |
| transaction length as the first read byte. */ |
| if (rdcount == 1 && (flags & I2C_M_RECV_LEN)) { |
| if (inval <= 0 || inval > I2C_SMBUS_BLOCK_MAX) { |
| if (!(flags & I2C_M_NO_RD_ACK)) |
| acknak(i2c_adap, 0); |
| // dev_err(&i2c_adap->dev, "readbytes: invalid " |
| // "block length (%d)\n", inval); |
| return -EREMOTEIO; |
| } |
| /* The original count value accounts for the extra |
| bytes, that is, either 1 for a regular transaction, |
| or 2 for a PEC transaction. */ |
| count += inval; |
| msg->len += inval; |
| } |
| |
| // bit_dbg(2, &i2c_adap->dev, "readbytes: 0x%02x %s\n", |
| // inval, |
| // (flags & I2C_M_NO_RD_ACK) |
| // ? "(no ack/nak)" |
| // : (count ? "A" : "NA")); |
| |
| if (!(flags & I2C_M_NO_RD_ACK)) { |
| inval = acknak(i2c_adap, count); |
| if (inval < 0) |
| return inval; |
| } |
| } |
| 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 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); |
| 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; |
| } |
| /* 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 */ |
| // dev_err(&i2c_adap->dev, "died at 2nd address code\n"); |
| return -EREMOTEIO; |
| } |
| 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) { |
| // dev_err(&i2c_adap->dev, |
| // "died at repeated 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 -ENXIO; |
| } |
| |
| 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; |
| |
| bit_dbg(3, &i2c_adap->dev, "emitting start condition\n"); |
| 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) { |
| bit_dbg(3, &i2c_adap->dev, "emitting " |
| "repeated start condition\n"); |
| i2c_repstart(adap); |
| } |
| ret = bit_doAddress(i2c_adap, pmsg); |
| if ((ret != 0) && !nak_ok) { |
| bit_dbg(1, &i2c_adap->dev, "NAK from " |
| "device addr 0x%02x msg #%d\n", |
| msgs[i].addr, i); |
| goto bailout; |
| } |
| } |
| if (pmsg->flags & I2C_M_RD) { |
| /* read bytes into buffer*/ |
| ret = readbytes(i2c_adap, pmsg); |
| if (ret >= 1) |
| bit_dbg(2, &i2c_adap->dev, "read %d byte%s\n", |
| ret, ret == 1 ? "" : "s"); |
| if (ret < pmsg->len) { |
| if (ret >= 0) |
| ret = -EREMOTEIO; |
| goto bailout; |
| } |
| } else { |
| /* write bytes from buffer */ |
| ret = sendbytes(i2c_adap, pmsg); |
| if (ret >= 1) |
| bit_dbg(2, &i2c_adap->dev, "wrote %d byte%s\n", |
| ret, ret == 1 ? "" : "s"); |
| if (ret < pmsg->len) { |
| if (ret >= 0) |
| ret = -EREMOTEIO; |
| goto bailout; |
| } |
| } |
| } |
| ret = i; |
| |
| bailout: |
| bit_dbg(3, &i2c_adap->dev, "emitting stop condition\n"); |
| i2c_stop(adap); |
| return ret; |
| } |
| |
| static u32 bit_func(struct i2c_adapter *adap) |
| { |
| return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | |
| I2C_FUNC_SMBUS_READ_BLOCK_DATA | |
| I2C_FUNC_SMBUS_BLOCK_PROC_CALL | |
| I2C_FUNC_10BIT_ADDR | I2C_FUNC_PROTOCOL_MANGLING; |
| } |
| |
| |
| /* -----exported algorithm data: ------------------------------------- */ |
| |
| static const struct i2c_algorithm i2c_bit_algo = { |
| .master_xfer = bit_xfer, |
| .functionality = bit_func, |
| }; |
| |
| /* |
| * registering functions to load algorithms at runtime |
| */ |
| static int i2c_bit_prepare_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; |
| // } |
| |
| /* register new adapter to i2c module... */ |
| adap->algo = &i2c_bit_algo; |
| adap->retries = 3; |
| |
| return 0; |
| } |
| |
| int i2c_bit_add_bus(struct i2c_adapter *adap) |
| { |
| int err; |
| |
| err = i2c_bit_prepare_bus(adap); |
| if (err) |
| return err; |
| |
| return 0; //i2c_add_adapter(adap); |
| } |
| |