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| author | Andi Shyti <andi.shyti@linux.intel.com> | 2026-08-22 14:19:12 +0200 |
|---|---|---|
| committer | Andi Shyti <andi.shyti@linux.intel.com> | 2026-08-22 14:19:34 +0200 |
| commit | d576a9561a1c80ae593539fb0ce0743d66825ac2 (patch) | |
| tree | 68f6de7e06b350afa42edeea2f7f33f086014597 /Documentation/userspace-api/ioctl/ioctl-decoding.rst | |
| download | linux-stable-d576a9561a1c80ae593539fb0ce0743d66825ac2.tar.gz linux-stable-d576a9561a1c80ae593539fb0ce0743d66825ac2.zip | |
Merge tag 'rust-i2c-for-7.3' into i2c/i2cgrafted
i2c: rust: mark I2cAdapter methods as inline
A single cleanup for the Rust I2C abstractions, targeting 7.3.
`I2cAdapter::get`, `inc_ref`, and `dec_ref` are trivial wrappers around
`i2c_get_adapter`/`i2c_put_adapter` and were showing up as their own
symbols in the build. Mark them `#[inline]` so they get folded into
their callers instead.
Signed-off-by: Igor Korotin <igor.korotin@linux.dev>
* tag 'rust-i2c-for-7.3':
i2c: rust: mark I2cAdapter methods as inline
Diffstat (limited to 'Documentation/userspace-api/ioctl/ioctl-decoding.rst')
| -rw-r--r-- | Documentation/userspace-api/ioctl/ioctl-decoding.rst | 31 |
1 files changed, 31 insertions, 0 deletions
diff --git a/Documentation/userspace-api/ioctl/ioctl-decoding.rst b/Documentation/userspace-api/ioctl/ioctl-decoding.rst new file mode 100644 index 000000000..380d6bb3e --- /dev/null +++ b/Documentation/userspace-api/ioctl/ioctl-decoding.rst @@ -0,0 +1,31 @@ +============================== +Decoding an IOCTL Magic Number +============================== + +To decode a hex IOCTL code: + +Most architectures use this generic format, but check +include/ARCH/ioctl.h for specifics, e.g. powerpc +uses 3 bits to encode read/write and 13 bits for size. + + ====== ================================== + bits meaning + ====== ================================== + 31-30 00 - no parameters: uses _IO macro + 10 - read: _IOR + 01 - write: _IOW + 11 - read/write: _IOWR + + 29-16 size of arguments + + 15-8 ascii character supposedly + unique to each driver + + 7-0 function # + ====== ================================== + + +So for example 0x82187201 is a read with arg length of 0x218, +character 'r' function 1. Grepping the source reveals this is:: + + #define VFAT_IOCTL_READDIR_BOTH _IOR('r', 1, struct dirent [2]) |
