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Add a new 'tr' (transfer) mode to i2c(8) to support more i2c controllers.

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Some i2c controller hardware does not provide a way to do individual START,
REPEAT-START and STOP actions on the i2c bus.  Instead, they can only do
a complete transfer as a single operation.  Typically they can do either
START-data-STOP or START-data-REPEATSTART-data-STOP.  In the i2c driver
framework, this corresponds to the iicbus_transfer method.  In the userland
interface they are initiated with the I2CRDWR ioctl command.

These changes add a new 'tr' mode which can be specified with the '-m'
command line option.  This mode should work on all hardware; when an i2c
controller driver doesn't directly support the iicbus_transfer method,
code in the i2c driver framework uses the lower-level START/REPEAT/STOP
methods to implement the transfer.  After this new mode has gotten some
testing on various hardware, the 'tr' mode should probably become the
new default mode.

PR:		189914
This commit is contained in:
Ian Lepore 2019-05-22 21:06:10 +00:00
parent 83d0c3846d
commit a30555576c
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=348120
2 changed files with 117 additions and 30 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

27
usr.sbin/i2c/i2c.8
View file

@ -25,7 +25,7 @@
.\"
.\" $FreeBSD$
.\"
.Dd January 23, 2009
.Dd May 22, 2019
.Dt I2C 8
.Os
.Sh NAME
@ -39,7 +39,7 @@
.Op Fl w Ar 0|8|16
.Op Fl o Ar offset
.Op Fl c Ar count
.Op Fl m Ar ss|rs|no
.Op Fl m Ar tr|ss|rs|no
.Op Fl b
.Op Fl v
.Nm
@ -72,10 +72,29 @@ number of bytes to transfer (dec).
transfer direction: r - read, w - write.
.It Fl f Ar device
I2C bus to use (default is /dev/iic0).
.It Fl m Ar ss|rs|no
.It Fl m Ar tr|ss|rs|no
addressing mode, i.e., I2C bus operations performed after the offset for the
transfer has been written to the device and before the actual read/write
operation. rs - repeated start; ss - stop start; no - none.
operation.
.Bl -tag -compact -offset indent
.It Va tr
complete-transfer
.It Va ss
stop then start
.It Va rs
repeated start
.It Va no
none
.El
Some I2C bus hardware does not provide control over the individual start,
repeat-start, and stop operations.
Such hardware can only perform a complete transfer of the offset and the
data as a single operation.
The
.Va tr
mode creates control structures describing the transfer and submits them
to the driver as a single complete transaction.
This mode works on all types of I2C hardware.
.It Fl n Ar skip_addr
skip address - address(es) to be skipped during bus scan.
There are two ways to specify addresses to ignore: by range 'a..b' or

120
usr.sbin/i2c/i2c.c
View file

@ -47,6 +47,7 @@ __FBSDID("$FreeBSD$");
#define I2C_MODE_NONE 1
#define I2C_MODE_STOP_START 2
#define I2C_MODE_REPEATED_START 3
#define I2C_MODE_TRANSFER 4
struct options {
int width;
@ -73,7 +74,7 @@ usage(void)
{
fprintf(stderr, "usage: %s -a addr [-f device] [-d [r|w]] [-o offset] "
"[-w [0|8|16]] [-c count] [-m [ss|rs|no]] [-b] [-v]\n",
"[-w [0|8|16]] [-c count] [-m [tr|ss|rs|no]] [-b] [-v]\n",
getprogname());
fprintf(stderr, " %s -s [-f device] [-n skip_addr] -v\n",
getprogname());
@ -297,24 +298,9 @@ static int
i2c_write(char *dev, struct options i2c_opt, char *i2c_buf)
{
struct iiccmd cmd;
int ch, i, error, fd, bufsize;
int error, fd, bufsize;
char *err_msg, *buf;
/*
* Read data to be written to the chip from stdin
*/
if (i2c_opt.verbose && !i2c_opt.binary)
fprintf(stderr, "Enter %u bytes of data: ", i2c_opt.count);
for (i = 0; i < i2c_opt.count; i++) {
ch = getchar();
if (ch == EOF) {
free(i2c_buf);
err(1, "not enough data, exiting\n");
}
i2c_buf[i] = ch;
}
fd = open(dev, O_RDWR);
if (fd == -1) {
free(i2c_buf);
@ -558,6 +544,72 @@ i2c_read(char *dev, struct options i2c_opt, char *i2c_buf)
return (1);
}
/*
* i2c_rdwr_transfer() - use I2CRDWR to conduct a complete i2c transfer.
*
* Some i2c hardware is unable to provide direct control over START, REPEAT-
* START, and STOP operations. Such hardware can only perform a complete
* START-<data>-STOP or START-<data>-REPEAT-START-<data>-STOP sequence as a
* single operation. The driver framework refers to this sequence as a
* "transfer" so we call it "transfer mode". We assemble either one or two
* iic_msg structures to describe the IO operations, and hand them off to the
* driver to be handled as a single transfer.
*/
static int
i2c_rdwr_transfer(char *dev, struct options i2c_opt, char *i2c_buf)
{
struct iic_msg msgs[2];
struct iic_rdwr_data xfer;
int fd, i;
union {
uint8_t buf[2];
uint8_t off8;
uint16_t off16;
} off;
i = 0;
if (i2c_opt.width > 0) {
msgs[i].flags = IIC_M_WR | IIC_M_NOSTOP;
msgs[i].slave = i2c_opt.addr;
msgs[i].buf = off.buf;
if (i2c_opt.width == 8) {
off.off8 = (uint8_t)i2c_opt.off;
msgs[i].len = 1;
} else {
off.off16 = (uint16_t)i2c_opt.off;
msgs[i].len = 2;
}
++i;
}
/*
* If the transfer direction is write and we did a write of the offset
* above, then we need to elide the start; this transfer is just more
* writing that follows the one started above. For a read, we always do
* a start; if we did an offset write above it'll be a repeat-start
* because of the NOSTOP flag used above.
*/
if (i2c_opt.dir == 'w')
msgs[i].flags = IIC_M_WR | (i > 0) ? IIC_M_NOSTART : 0;
else
msgs[i].flags = IIC_M_RD;
msgs[i].slave = i2c_opt.addr;
msgs[i].len = i2c_opt.count;
msgs[i].buf = i2c_buf;
++i;
xfer.msgs = msgs;
xfer.nmsgs = i;
if ((fd = open(dev, O_RDWR)) == -1)
err(1, "open(%s) failed", dev);
if (ioctl(fd, I2CRDWR, &xfer) == -1 )
err(1, "ioctl(I2CRDWR) failed");
close(fd);
return (0);
}
int
main(int argc, char** argv)
{
@ -620,6 +672,8 @@ main(int argc, char** argv)
i2c_opt.mode = I2C_MODE_STOP_START;
else if (!strcmp(optarg, "rs"))
i2c_opt.mode = I2C_MODE_REPEATED_START;
else if (!strcmp(optarg, "tr"))
i2c_opt.mode = I2C_MODE_TRANSFER;
else
usage();
break;
@ -687,19 +741,33 @@ main(int argc, char** argv)
if (i2c_buf == NULL)
err(1, "data malloc");
/*
* For a write, read the data to be written to the chip from stdin.
*/
if (i2c_opt.dir == 'w') {
error = i2c_write(dev, i2c_opt, i2c_buf);
if (error) {
free(i2c_buf);
return (1);
if (i2c_opt.verbose && !i2c_opt.binary)
fprintf(stderr, "Enter %u bytes of data: ",
i2c_opt.count);
for (i = 0; i < i2c_opt.count; i++) {
ch = getchar();
if (ch == EOF) {
free(i2c_buf);
err(1, "not enough data, exiting\n");
}
i2c_buf[i] = ch;
}
}
if (i2c_opt.dir == 'r') {
if (i2c_opt.mode == I2C_MODE_TRANSFER)
error = i2c_rdwr_transfer(dev, i2c_opt, i2c_buf);
else if (i2c_opt.dir == 'w')
error = i2c_write(dev, i2c_opt, i2c_buf);
else
error = i2c_read(dev, i2c_opt, i2c_buf);
if (error) {
free(i2c_buf);
return (1);
}
if (error != 0) {
free(i2c_buf);
return (1);
}
if (i2c_opt.verbose)