* [PATCH v3 1/2] i2c-tools: Allow passing device file paths
2026-05-30 20:06 [PATCH v3 0/2] i2c-tools: Make tools accept bus path Brigham Campbell
@ 2026-05-30 20:06 ` Brigham Campbell
2026-05-30 20:06 ` [PATCH v3 2/2] i2c-tools: Document device paths as I2CBUS arg Brigham Campbell
2026-07-06 3:46 ` [PATCH v3 0/2] i2c-tools: Make tools accept bus path Stephen Horvath
2 siblings, 0 replies; 6+ messages in thread
From: Brigham Campbell @ 2026-05-30 20:06 UTC (permalink / raw)
To: Jean Delvare, linux-i2c
Cc: Wolfram Sang, Brigham Campbell, Gero Schwäricke
Make i2c-tools binaries accept a device file path or symlink directly.
This is useful, for example, for use with stable symlinks generated by
udev.
In the case of conflict, the bus parameter is parsed with the following
precedence in order to maintain backwards compatibility:
number -> name -> device path
Suggested-by: Gero Schwäricke <gero.schwaericke@sevenlab.de>
Signed-off-by: Brigham Campbell <me@brighamcampbell.com>
---
tools/i2cbusses.c | 40 ++++++++++++++++++++++++++++++++++------
tools/i2cbusses.h | 4 +++-
tools/i2cdetect.c | 12 ++++--------
tools/i2cdump.c | 12 ++++--------
tools/i2cget.c | 11 ++++-------
tools/i2cset.c | 11 ++++-------
tools/i2ctransfer.c | 11 ++++-------
7 files changed, 57 insertions(+), 44 deletions(-)
diff --git a/tools/i2cbusses.c b/tools/i2cbusses.c
index d687615..54f3238 100644
--- a/tools/i2cbusses.c
+++ b/tools/i2cbusses.c
@@ -65,7 +65,7 @@ static enum adt i2c_get_funcs(int i2cbus)
char filename[20];
enum adt ret;
- file = open_i2c_dev(i2cbus, filename, sizeof(filename), 1);
+ file = open_i2c_dev_num(i2cbus, filename, sizeof(filename), 1);
if (file < 0)
return adt_unknown;
@@ -348,10 +348,6 @@ static int lookup_i2c_bus_by_name(const char *bus_name)
}
}
- if (i2cbus == -1)
- fprintf(stderr, "Error: I2C bus name doesn't match any "
- "bus present!\n");
-
done:
free_adapters(adapters);
return i2cbus;
@@ -410,7 +406,7 @@ int parse_i2c_address(const char *address_arg, int all_addrs)
return address;
}
-int open_i2c_dev(int i2cbus, char *filename, size_t size, int quiet)
+int open_i2c_dev_num(int i2cbus, char *filename, size_t size, int quiet)
{
int file, len;
@@ -446,6 +442,38 @@ int open_i2c_dev(int i2cbus, char *filename, size_t size, int quiet)
return file;
}
+int open_i2c_dev_path(const char *i2cbus_arg, int quiet)
+{
+ int file = open(i2cbus_arg, O_RDWR);
+
+ if (file < 0 && !quiet) {
+ fprintf(stderr, "Error: Could not open file "
+ "`%s': %s\n", i2cbus_arg, strerror(errno));
+ if (errno == EACCES)
+ fprintf(stderr, "Run as root?\n");
+ }
+
+ return file;
+}
+
+int open_i2c_dev(char *i2cbus_arg, char **filename, size_t size, int quiet)
+{
+ int file, i2cbus;
+
+ i2cbus = lookup_i2c_bus(i2cbus_arg);
+
+ if (i2cbus < 0) {
+ *filename = i2cbus_arg;
+ file = open_i2c_dev_path(i2cbus_arg, quiet);
+ if (file < 0)
+ fprintf(stderr, "Failed to open `%s' as a bus name "
+ "and as a path.\n", i2cbus_arg);
+ return file;
+ }
+
+ return open_i2c_dev_num(i2cbus, *filename, size, quiet);
+}
+
int set_slave_addr(int file, int address, int force)
{
/* With force, let the user read from/write to the registers
diff --git a/tools/i2cbusses.h b/tools/i2cbusses.h
index 6f901b6..5de3056 100644
--- a/tools/i2cbusses.h
+++ b/tools/i2cbusses.h
@@ -31,7 +31,9 @@ void free_adapters(struct i2c_adap *adapters);
int lookup_i2c_bus(const char *i2cbus_arg);
int parse_i2c_address(const char *address_arg, int all_addrs);
-int open_i2c_dev(int i2cbus, char *filename, size_t size, int quiet);
+int open_i2c_dev(char *i2cbus_arg, char **filename, size_t size, int quiet);
+int open_i2c_dev_num(int i2cbus, char *filename, size_t size, int quiet);
+int open_i2c_dev_path(const char *i2cbus_arg, int quiet);
int set_slave_addr(int file, int address, int force);
#define MISSING_FUNC_FMT "Error: Adapter does not have %s capability\n"
diff --git a/tools/i2cdetect.c b/tools/i2cdetect.c
index bb2f146..208ac6c 100644
--- a/tools/i2cdetect.c
+++ b/tools/i2cdetect.c
@@ -205,8 +205,9 @@ static void print_i2c_busses(void)
int main(int argc, char *argv[])
{
char *end;
- int i2cbus, file, res;
- char filename[20];
+ int file, res;
+ char filename_buf[20];
+ char *filename = filename_buf;
unsigned long funcs;
int mode = MODE_AUTO;
int first = 0x08, last = 0x77;
@@ -269,11 +270,6 @@ int main(int argc, char *argv[])
help();
exit(1);
}
- i2cbus = lookup_i2c_bus(argv[optind]);
- if (i2cbus < 0) {
- help();
- exit(1);
- }
/* read address range if present */
if (argc == optind + 3 && mode != MODE_FUNC) {
@@ -313,7 +309,7 @@ int main(int argc, char *argv[])
exit(1);
}
- file = open_i2c_dev(i2cbus, filename, sizeof(filename), 0);
+ file = open_i2c_dev(argv[optind], &filename, sizeof(filename_buf), 0);
if (file < 0) {
exit(1);
}
diff --git a/tools/i2cdump.c b/tools/i2cdump.c
index d315e2f..ce3be2c 100644
--- a/tools/i2cdump.c
+++ b/tools/i2cdump.c
@@ -100,9 +100,10 @@ static int check_funcs(int file, int size, int pec)
int main(int argc, char *argv[])
{
char *end;
- int i, j, res, i2cbus, address, size, file;
+ int i, j, res, address, size, file;
int bank = 0, bankreg = 0x4E, old_bank = 0;
- char filename[20];
+ char filename_buf[20];
+ char *filename = filename_buf;
int block[256];
int pec = 0, even = 0;
int opt;
@@ -135,11 +136,6 @@ int main(int argc, char *argv[])
help();
exit(1);
}
- i2cbus = lookup_i2c_bus(argv[optind]);
- if (i2cbus < 0) {
- help();
- exit(1);
- }
if (argc < optind + 2) {
fprintf(stderr, "Error: No address specified!\n");
@@ -235,7 +231,7 @@ int main(int argc, char *argv[])
}
}
- file = open_i2c_dev(i2cbus, filename, sizeof(filename), 0);
+ file = open_i2c_dev(argv[optind], &filename, sizeof(filename_buf), 0);
if (file < 0
|| check_funcs(file, size, pec)
|| set_slave_addr(file, address, force))
diff --git a/tools/i2cget.c b/tools/i2cget.c
index 17d78bf..e08ee81 100644
--- a/tools/i2cget.c
+++ b/tools/i2cget.c
@@ -169,9 +169,10 @@ static int confirm(const char *filename, int address, int size, int daddress,
int main(int argc, char *argv[])
{
char *end;
- int res, i2cbus, address, size, file;
+ int res, address, size, file;
int daddress;
- char filename[20];
+ char filename_buf[20];
+ char *filename = filename_buf;
int pec = 0;
int opt;
int force = 0, yes = 0, version = 0, all_addrs = 0;
@@ -199,10 +200,6 @@ int main(int argc, char *argv[])
if (argc < optind + 2)
help(1);
- i2cbus = lookup_i2c_bus(argv[optind]);
- if (i2cbus < 0)
- help(1);
-
address = parse_i2c_address(argv[optind+1], all_addrs);
if (address < 0)
help(1);
@@ -251,7 +248,7 @@ int main(int argc, char *argv[])
length = I2C_SMBUS_BLOCK_MAX;
}
- file = open_i2c_dev(i2cbus, filename, sizeof(filename), 0);
+ file = open_i2c_dev(argv[optind], &filename, sizeof(filename_buf), 0);
if (file < 0
|| check_funcs(file, size, daddress, pec)
|| set_slave_addr(file, address, force))
diff --git a/tools/i2cset.c b/tools/i2cset.c
index aaf7faf..8371570 100644
--- a/tools/i2cset.c
+++ b/tools/i2cset.c
@@ -151,9 +151,10 @@ int main(int argc, char *argv[])
{
char *end;
const char *maskp = NULL;
- int res, i2cbus, address, size, file;
+ int res, address, size, file;
int value, daddress, vmask = 0;
- char filename[20];
+ char filename_buf[20];
+ char *filename = filename_buf;
int pec = 0;
int opt;
int force = 0, yes = 0, version = 0, readback = 0, all_addrs = 0;
@@ -183,10 +184,6 @@ int main(int argc, char *argv[])
if (argc < optind + 3)
help(1);
- i2cbus = lookup_i2c_bus(argv[optind]);
- if (i2cbus < 0)
- help(1);
-
address = parse_i2c_address(argv[optind+1], all_addrs);
if (address < 0)
help(1);
@@ -301,7 +298,7 @@ int main(int argc, char *argv[])
}
}
- file = open_i2c_dev(i2cbus, filename, sizeof(filename), 0);
+ file = open_i2c_dev(argv[optind], &filename, sizeof(filename_buf), 0);
if (file < 0
|| check_funcs(file, size, pec)
|| set_slave_addr(file, address, force))
diff --git a/tools/i2ctransfer.c b/tools/i2ctransfer.c
index 4db98e3..b7b46fd 100644
--- a/tools/i2ctransfer.c
+++ b/tools/i2ctransfer.c
@@ -142,8 +142,9 @@ static int confirm(const char *filename, struct i2c_msg *msgs, __u32 nmsgs)
int main(int argc, char *argv[])
{
- char filename[20];
- int i2cbus, address = -1, file, opt, nmsgs = 0, nmsgs_sent, i;
+ char filename_buf[20];
+ char *filename = filename_buf;
+ int address = -1, file, opt, nmsgs = 0, nmsgs_sent, i;
int force = 0, yes = 0, version = 0, verbose = 0, all_addrs = 0, binary = 0;
struct i2c_msg msgs[I2C_RDRW_IOCTL_MAX_MSGS];
enum parse_state state = PARSE_GET_DESC;
@@ -177,11 +178,7 @@ int main(int argc, char *argv[])
exit(1);
}
- i2cbus = lookup_i2c_bus(argv[optind++]);
- if (i2cbus < 0)
- exit(1);
-
- file = open_i2c_dev(i2cbus, filename, sizeof(filename), 0);
+ file = open_i2c_dev(argv[optind++], &filename, sizeof(filename_buf), 0);
if (file < 0 || check_funcs(file))
exit(1);
--
2.54.0
^ permalink raw reply related [flat|nested] 6+ messages in thread* [PATCH v3 2/2] i2c-tools: Document device paths as I2CBUS arg
2026-05-30 20:06 [PATCH v3 0/2] i2c-tools: Make tools accept bus path Brigham Campbell
2026-05-30 20:06 ` [PATCH v3 1/2] i2c-tools: Allow passing device file paths Brigham Campbell
@ 2026-05-30 20:06 ` Brigham Campbell
2026-07-06 3:46 ` [PATCH v3 0/2] i2c-tools: Make tools accept bus path Stephen Horvath
2 siblings, 0 replies; 6+ messages in thread
From: Brigham Campbell @ 2026-05-30 20:06 UTC (permalink / raw)
To: Jean Delvare, linux-i2c; +Cc: Wolfram Sang, Brigham Campbell
i2c-tools now accept device file paths in addition to the i2c adapter
number and i2c adapter name. Add this capability to documentation.
Signed-off-by: Brigham Campbell <me@brighamcampbell.com>
---
tools/i2cdetect.8 | 8 ++++----
tools/i2cdetect.c | 2 +-
tools/i2cdump.8 | 7 ++++---
tools/i2cdump.c | 2 +-
tools/i2cget.8 | 9 +++++----
tools/i2cget.c | 2 +-
tools/i2cset.8 | 12 ++++++------
tools/i2cset.c | 2 +-
tools/i2ctransfer.8 | 2 +-
tools/i2ctransfer.c | 2 +-
10 files changed, 25 insertions(+), 23 deletions(-)
diff --git a/tools/i2cdetect.8 b/tools/i2cdetect.8
index 5935b2b..fdfff62 100644
--- a/tools/i2cdetect.8
+++ b/tools/i2cdetect.8
@@ -26,10 +26,10 @@ i2cdetect \- detect I2C chips
.SH DESCRIPTION
i2cdetect is a userspace program to scan an I2C bus for devices. It
outputs a table with the list of detected devices on the specified bus.
-\fIi2cbus\fR indicates the number or name of the I2C bus to be scanned, and
-should correspond to one of the busses listed by \fIi2cdetect -l\fR.
-The optional parameters \fIfirst\fR and \fIlast\fR restrict the scanning
-range (default: from 0x08 to 0x77).
+\fIi2cbus\fR indicates the number, name, or device file path of the I2C
+bus to be scanned, and should correspond to one of the busses listed by
+\fIi2cdetect -l\fR. The optional parameters \fIfirst\fR and \fIlast\fR
+restrict the scanning range (default: from 0x08 to 0x77).
.PP
As there is no standard I2C detection command, i2cdetect uses arbitrary
SMBus commands (namely SMBus quick write and SMBus receive byte) to probe
diff --git a/tools/i2cdetect.c b/tools/i2cdetect.c
index 208ac6c..92d6c81 100644
--- a/tools/i2cdetect.c
+++ b/tools/i2cdetect.c
@@ -38,7 +38,7 @@ static void help(void)
"Usage: i2cdetect [-y] [-a] [-q|-r] I2CBUS [FIRST LAST]\n"
" i2cdetect -F I2CBUS\n"
" i2cdetect -l\n"
- " I2CBUS is an integer or an I2C bus name\n"
+ " I2CBUS is an integer, I2C bus name, or I2C bus device path\n"
" If provided, FIRST and LAST limit the probing range.\n");
}
diff --git a/tools/i2cdump.8 b/tools/i2cdump.8
index 6ede625..103051d 100644
--- a/tools/i2cdump.8
+++ b/tools/i2cdump.8
@@ -52,9 +52,10 @@ scripts.
Allow using addresses between 0x00 - 0x07 and 0x78 - 0x7f. Not recommended.
.PP
At least two options must be provided to i2cdump. \fIi2cbus\fR indicates the
-number or name of the I2C bus to be scanned. This number should correspond to one
-of the busses listed by \fIi2cdetect -l\fR. \fIaddress\fR indicates the
-address to be scanned on that bus, and is an integer between 0x08 and 0x77.
+number, name, or device file path of the I2C bus to be scanned. This number
+should correspond to one of the busses listed by \fIi2cdetect -l\fR.
+\fIaddress\fR indicates the address to be scanned on that bus, and is an integer
+between 0x08 and 0x77.
.PP
The \fImode\fR parameter, if specified, is one of the letters \fBb\fP, \fBw\fP,
or \fBi\fP, corresponding to a read size of a single byte, a 16-bit
diff --git a/tools/i2cdump.c b/tools/i2cdump.c
index ce3be2c..6389e68 100644
--- a/tools/i2cdump.c
+++ b/tools/i2cdump.c
@@ -32,7 +32,7 @@ static void help(void)
{
fprintf(stderr,
"Usage: i2cdump [-f] [-y] [-r first-last] [-a] I2CBUS ADDRESS [MODE [BANK [BANKREG]]]\n"
- " I2CBUS is an integer or an I2C bus name\n"
+ " I2CBUS is an integer, I2C bus name, or I2C bus device path\n"
" ADDRESS is an integer (0x08 - 0x77, or 0x00 - 0x7f if -a is given)\n"
" MODE is one of:\n"
" b (byte, default)\n"
diff --git a/tools/i2cget.8 b/tools/i2cget.8
index 69586cc..ba261a9 100644
--- a/tools/i2cget.8
+++ b/tools/i2cget.8
@@ -45,10 +45,11 @@ scripts. Use with caution.
.B -a
Allow using addresses between 0x00 - 0x07 and 0x78 - 0x7f. Not recommended.
.PP
-There are two required options to i2cget. \fIi2cbus\fR indicates the number
-or name of the I2C bus to be scanned. This number should correspond to one of
-the busses listed by \fIi2cdetect -l\fR. \fIchip-address\fR specifies the
-address of the chip on that bus, and is an integer between 0x08 and 0x77.
+There are two required options to i2cget. \fIi2cbus\fR indicates the number,
+name, or device file path of the I2C bus to be scanned. This number should
+correspond to one of the busses listed by \fIi2cdetect -l\fR.
+\fIchip-address\fR specifies the address of the chip on that bus, and is an
+integer between 0x08 and 0x77.
.PP
\fIdata-address\fR specifies the address on that chip to read from, and is
an integer between 0x00 and 0xFF. If omitted, the currently active register
diff --git a/tools/i2cget.c b/tools/i2cget.c
index e08ee81..759f016 100644
--- a/tools/i2cget.c
+++ b/tools/i2cget.c
@@ -35,7 +35,7 @@ static void __attribute__ ((noreturn)) help(int status)
{
fprintf(stderr,
"Usage: i2cget [-f] [-y] [-a] I2CBUS CHIP-ADDRESS [DATA-ADDRESS [MODE [LENGTH]]]\n"
- " I2CBUS is an integer or an I2C bus name\n"
+ " I2CBUS is an integer, I2C bus name, or I2C bus device path\n"
" ADDRESS is an integer (0x08 - 0x77, or 0x00 - 0x7f if -a is given)\n"
" MODE is one of:\n"
" b (read byte data, default)\n"
diff --git a/tools/i2cset.8 b/tools/i2cset.8
index e4e1870..d7a2c05 100644
--- a/tools/i2cset.8
+++ b/tools/i2cset.8
@@ -65,12 +65,12 @@ apply as those of option \fB-m\fR.
.B -a
Allow using addresses between 0x00 - 0x07 and 0x78 - 0x7f. Not recommended.
.PP
-There are three required options to i2cset. \fIi2cbus\fR indicates the number
-or name of the I2C bus to be scanned. This number should correspond to one of
-the busses listed by \fIi2cdetect -l\fR. \fIchip-address\fR specifies the
-address of the chip on that bus, and is an integer between 0x08 and 0x77.
-\fIdata-address\fR specifies the address on that chip to write to, and is an
-integer between 0x00 and 0xFF.
+There are three required options to i2cset. \fIi2cbus\fR indicates the number,
+name, or device file path of the I2C bus to be scanned. This number should
+correspond to one of the busses listed by \fIi2cdetect -l\fR. \fIchip-address\fR
+specifies the address of the chip on that bus, and is an integer between 0x08
+and 0x77. \fIdata-address\fR specifies the address on that chip to write to, and
+is an integer between 0x00 and 0xFF.
.PP
The \fIvalue\fR parameter, if specified, is the value to write to that
location on the chip. If this parameter is omitted, then a short write is
diff --git a/tools/i2cset.c b/tools/i2cset.c
index 8371570..27e3c7f 100644
--- a/tools/i2cset.c
+++ b/tools/i2cset.c
@@ -32,7 +32,7 @@ static void __attribute__ ((noreturn)) help(int status)
{
fprintf(stderr,
"Usage: i2cset [-f] [-y] [-m MASK] [-r] [-a] I2CBUS CHIP-ADDRESS DATA-ADDRESS [VALUE] ... [MODE]\n"
- " I2CBUS is an integer or an I2C bus name\n"
+ " I2CBUS is an integer, I2C bus name, or I2C bus device path\n"
" ADDRESS is an integer (0x08 - 0x77, or 0x00 - 0x7f if -a is given)\n"
" MODE is one of:\n"
" c (byte, no value)\n"
diff --git a/tools/i2ctransfer.8 b/tools/i2ctransfer.8
index 4bdf436..012ca69 100644
--- a/tools/i2ctransfer.8
+++ b/tools/i2ctransfer.8
@@ -84,7 +84,7 @@ This is mainly meant to be used in scripts.
.PP
The first parameter
.I i2cbus
-indicates the number or name of the I2C bus to be used.
+indicates the number, name, or device file path of the I2C bus to be used.
This number should correspond to one of the busses listed by
.B i2cdetect -l.
diff --git a/tools/i2ctransfer.c b/tools/i2ctransfer.c
index b7b46fd..05299c1 100644
--- a/tools/i2ctransfer.c
+++ b/tools/i2ctransfer.c
@@ -51,7 +51,7 @@ static void help(void)
" -v verbose mode\n"
" -V version info\n"
" -y yes to all confirmations\n"
- " I2CBUS is an integer or an I2C bus name\n"
+ " I2CBUS is an integer, I2C bus name, or I2C bus device path\n"
" DESC describes the transfer in the form: {r|w}LENGTH[@address]\n"
" 1) read/write-flag 2) LENGTH (range 0-65535, or '?')\n"
" 3) I2C address (use last one if omitted)\n"
--
2.54.0
^ permalink raw reply related [flat|nested] 6+ messages in thread